Colorectal Cancer Progression Research Articles

Abstract 7075: Global epitranscriptomic and transcriptomic footprint revealed upregulation of methylated single minded 2-small variant (meSIM2-SV) in colorectal cancer (CRC) by NTMT1(METTL11A) via m6A-YTHDF1-dependent manner

Abstract Establishing global footprint of altered m6A mRNA is a unique method to identify the new prognostics biomarkers. Altered N6-methyladenosine(m6A) RNA methylation regulates cancer progression with uncharacterized mechanism. Here, we present novel link between m6A modification on 5’-UTR SIM2-SV contribution in colorectal cancer progression. MeRIP and RNA-seq data from 68 fresh frozen CRC samples revealed 13,843 altered m6A methylated peaks and found highest in chromosomes 1, 2, and 3. Analysis uncovered 119 overlapping genes and clusters into 32 up-regulated genes with 56 up-hyper peaks, 8 up-regulated genes with 9 up-hypo peaks, 12 down-regulated genes with 14 down-hyper peaks, and 28 down-regulated genes with 40 down-hypo peaks. A significant increase in the SIM2 m6A and RNA level led us to perform correlation analysis between the SIM2SV and m6A RNA regulators. SIM2SV was significantly correlated with YTHDF1 m6A-readers and m6A-NTMT1 writer, suggesting important roles of SIM2SV in CRC oncogenicity. m6A-sequencing identified m6A enrichment in 5’-UTR of SIM2SV gene which further verified. siNTMT1 and siYTHDF1 manipulation in HCT116 and RKO cell lines verified a decrease in SIM2SV gene/protein expression, and m6A level. Knockdown effects also showed decrease in cell proliferation, clonogenicity and induced cell cycle arrest in the G2/M phase for NTMT1 and YTHDF1 versus SIM2 Knockdown showed cell cycle arrest in S/G2 phase. Our investigation revealed the role of new writer NTMT1 for methylated SIM2SV gene expression in colorectal cancer proliferation via m6A-YTHDF1(as “decoder”) dependent manner. Further investigation on m6A modification specifically on SIM2 mRNA revealed the essential roles of its writer NTMT1 and its reader YTHDF1 in CRC development, evidently supporting the importance of the unique landscape of m6A epigenetic modification in colorectal neoplasm, which not only advance our understanding of CRC pathobiology but also provides a new set of molecular targets for building up effective tools to fight CRC. Citation Format: Sudhir Kumar Rai, Ting Gong, Zitong Gao, Yujia Qin, Matthew Huo, Ken Nakastu, Hua Yang, Yuanyuan Fu, Lang Wu, Mayumi Jijiwa, Masaki Nasu, Shaoqiu Chen, Gang Huang, Peiwen Fei, Youping Deng. Global epitranscriptomic and transcriptomic footprint revealed upregulation of methylated single minded 2-small variant (meSIM2-SV) in colorectal cancer (CRC) by NTMT1(METTL11A) via m6A-YTHDF1-dependent manner [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7075.

Abstract 6207: Exploring colorectal cancer with ARIA: Biomedical insights

Abstract Gaining the promised benefits from the population-scale datasets, both clinical and genomic, is often hindered by the inability to easily access, explore and manipulate such complex data - a difficulty that ARIA was designed to overcome. In the field of biomedicine, organizations harness extensive datasets, gaining profound insights into patients and participants, thereby unleashing possibilities for accelerating research, especially in the realms of drug development and precision medicine. To facilitate navigation through the intricate landscape of biomedical data, Velsera has innovated ARIA to catalyse efficient and insightful analysis, with a keen emphasis on user-friendliness to ensure accessibility across a diverse professional audience. To demonstrate the practical application of ARIA, we explore genomic and clinical datasets to identify key differences in colorectal cancer progression. CRC, the third most common cancer globally, has unique characteristics in origination and progression from benign to pathogenic. Here we investigate differences between patients with polyps that do and do not progress to CRC, including key environmental factors such as smoking history, inactive lifestyle and obesity in conjunction with their known clinical and genetic risk factors. This exploration into the abilities of ARIA demonstrate the ability to analyse complex datasets combining both clinical and genomics data at a large scale. For the purpose of this demonstration, a Synthea Dataset, encompassing synthetic clinical and genomic data for 122,011 patients across various age groups, was utilized. This dataset was generated by Velsera specifically for testing ARIA functionalities. In conclusion, ARIA empowers efficient analysis of complex biomedical datasets, providing a comprehensive understanding of disease mechanisms and facilitating valuable insights. Citation Format: Nevena Nikolic, Sarah Kleinstein, Jelena Radenkovic, Milan Kovacevic. Exploring colorectal cancer with ARIA: Biomedical insights [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6207.

Abstract 4112: Identification of Th1-specific epitopes from non-mutated KRAS lesions for off-the-shelf cancer vaccines

Abstract Background KRAS is crucial for cell growth, differentiation, and signaling. Mutations in the KRAS gene (i.e., codon 12 or 13) are frequently associated with the development and progression of cancer, particularly lung, colorectal, and pancreatic cancers. Recently, it has been captured that KRAS targeting cancer vaccine research and clinical trials have been conducted in certain tumor types and vaccine approaches are encouraged to move forward. It has been well known that the tumor-eradicating efficacy of cancer vaccines arises from Th1 epitope selection. While tumor growth may persist after immunization with non-selected epitopes (including full-length), immunization with a highly selected Th1-specific epitope vaccine can lead to tumor regression by suppressing the activation of immune inhibitory cells. The Th-Vac® discovery platform uses a combination of in-silico, in-vitro, and in-vivo studies to precisely identify Th1-specific epitopes. It consists of two modules: module 1 (in-silico) and module 2 (in-vitro and efficacy evaluation). The aim is to identify MHC class II epitopes that are specific to antigens for CD4+ T cells, displaying the most favorable binding affinity across diverse alleles. Th1-specific epitope vaccines aim to boost and sustain T cell immunity against tumor antigens, overcoming the lack of a precise T cell response or pre-existing tolerance in the immunosuppressive TME. This study aimed to explore Th1-specific epitopes for KRAS vaccine to be potentially effective in numerous KRAS mutation-driven cancers. Methods Peptide sequence candidates that have highly potential of MHC class II binding affinity were comprehensively predicted via a module 1 (ASEP program). All of peptides selected in ASEP were synthesized as 15 mers. Each peptide was evaluated for immunogenicity using ELISpot and/or FACS analysis in module 2 (2a for in vitro and 2b for in vivo immunologic evaluation) of the Th-Vac® discovery platform. Specifically, in Module 2b, immunogenicity was evaluated using a 38-mer peptide formed by combining five overlapping peptides selected in 2a. These kinds of immunogenicity evaluations were conducted using type 1 and/or type 2 cytokine(s) produced by CD4+ T cells. Results In ASEP prediction, twelve peptides were selected as potential candidates demonstrating a high affinity to MHC class II, which were in different lesions of common mutation of KRAS. In module 2 using ELISpot and FACS analysis, two epitopes (non-mutated sequences) were finally selected as Th1-specific epitopes based on the type 1 T cell response. Conclusion Unlike previous vaccines using mutant lesions, in this study, two non-mutated Th1-specific epitopes are under the in-vivo efficacy studies as mono and combining regimen(s) in certain tumor types. Additionally, the Th-Vac® platform was fully validated in terms of the performance and its application would be expanded beyond a cancer vaccine. Citation Format: Youngki Choi, Jinback Lim, Hyo-Hyun Park, Jinho Kang, Hun Jung. Identification of Th1-specific epitopes from non-mutated KRAS lesions for off-the-shelf cancer vaccines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4112.

Abstract 6311: From bench to bedside: GMP manufacturing and testing of an LGR5-targeting CAR-T against colorectal cancer

Abstract Colorectal cancer is the third most diagnosed cancer worldwide, and is responsible for the second largest number of cancer related deaths, warranting the need for new treatments. The successful use of chimeric antigen receptor T (CAR-T) cells against B-cell malignancies has inspired the search for CAR-T cell therapies against solid tumours such as colorectal cancer. Cancer stem cells (CSC) are a small population of cells within a tumour with the capacity to self-renew, differentiate, and initiate new tumours. CSC are resistant to chemotherapy and radiotherapy and are enriched in residual disease. Targeting CSC is a strategy to reduce the tumours’ ability to generate new cells. Leucine-rich G protein-coupled receptor 5 (LGR5) is a marker of CSC and LGR5+ cancer cells are implicated in tumour progression and metastasis in colorectal cancer. We designed and tested a chimeric antigen receptor (CAR) targeting the extracellular domain of LGR5. LGR5-targeting CAR-T cells showed significant antigen-specific cytotoxicity and IFNγ release against colorectal cancer (CRC) cell lines in vitro, and in vivo efficacy in a CRC xenograft mouse model. We confirmed the specificity and safety of the LGR5 targeting CAR-T cells by testing against normal human tissues. A GMP ready protocol for clinical scale manufacture of LGR5-targeting CAR-T cells have been developed using CD3+ T-cells from healthy donors. We have successfully tested this protocol using CRC patient-derived CD3+ T-cells and were able to generate clinically relevant cell numbers (80-fold expansion) with high CAR expression. Cells manufactured using this GMP protocol expressed markers of self-renewing naïve-like and central memory phenotype and showed very low percentage of cells that were triple-positive for PD1, TIM3 and LAG3. This protocol has been successfully tested and validated in a GMP manufacturing facility for the production of LGR5 targeting CAR-T cells, in preparation for an FDA approved first in man clinical trial against metastatic colorectal cancer, starting in 2023 (NCT05759728). Citation Format: Veronika Bandara, Batjargal Gundsambuu, Silvana Napoli, Jade Foeng, Dylan McPeake, Timona Tylis, Emma Thompson, Stuart Mills, Allison Cowin, Claudine Bonder, Timothy Sadlon, Shaun McColl, Simon Barry. From bench to bedside: GMP manufacturing and testing of an LGR5-targeting CAR-T against colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6311.

Abstract 1282: Gavage with Candida albicans leads to fungal colonization of colorectal tumors and decreased response to radiotherapy

Abstract The host microbiome in the gut and tumors have been shown to affect tumor growth and therapeutic response in cancer. Furthermore, the presence of specific fungal taxa are associated with tumor hypoxia, tumor progression, therapeutic response, and clinical outcomes in colorectal cancer (CRC). Preliminary data from our group found that the presence of Candida species increased tumor hypoxia and decreased overall survival in CRC. However, whether intratumoral Candida drive, support, or simply inhabit tumors with poor prognoses remains unclear. Here, we investigate a casual role for Candida albicans in tumor progression and therapy response using a syngeneic mouse model of microsatellite-instability high (MSI-H) colorectal cancer. We subcutaneously implanted MC38 colorectal cancer cells into C57BL/6 mice and then orally gavaged these mice with C. albicans, Saccharomyces cerevisiae, or PBS. The site of tumor formation was locally irradiated once (7.5 Gy), and growth of the tumor was measured over time. Differences in tumor volume were assessed by longitudinal mixed-effect models. Tumor sections were stained for fungi using calcofluor white (CFW) and underwent bulk RNA sequencing to detect differential gene expression, which were interpreted using gene set enrichment analysis (GSEA). Mice gavaged with C. albicans showed decreased response to radiation compared to mice gavaged with either S. cerevisiae (p<0.05) or PBS (p<0.001). Additionally, hyphae were observed in murine tumors gavaged with C. albicans, suggesting translocation of gavaged C. albicans from the gut to tumors. Further, tumors from mice gavaged with C. albicans displayed unique gene expression profiles, including decreased interferon alpha and IL-6 and STAT3 signaling, decreased oxidative phosphorylation, and decreased apoptosis-related gene expression. Here, we show that C. albicans may confer resistance to radiation therapy and affects immune and cancer cell activity in the MC38 (MSI-H) syngeneic in vivo model of colorectal cancer. Further, we show that hyphal fungi can be visualized in heterotopic murine tumors from our C. albicans gavage condition. These data establish that fungi can translocate from the gut to distal tumor sites, and that upon translocation, changes in gene expression and therapy response are observed. Future directions will explore the mechanism by which these effects occur and whether these findings can be leveraged to improve radiotherapy outcomes. Citation Format: Dennis J. Grencewicz, Alexander Loncar, Rebecca Hoyd, Aaditya Pallerla, Nyelia Williams, Martin Benej, McKenzie Kreamer, Yogita Mehra, Shiva Jahanbakhshi, Matthew Anderson, Nicholas Denko, Daniel Spakowicz. Gavage with Candida albicans leads to fungal colonization of colorectal tumors and decreased response to radiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1282.

Abstract 6806: Single cell RNA sequencing of human and murine cancers demonstrates metastases-specific neutrophil phenotypes driven by the IL-1β/CXCR2 signaling axis - Disruption of this pathway abrogates neutrophil immunosuppressive effects and reduces tumor burden

Abstract Introduction: Neutrophils are a highly heterogenous, plastic cell population, known to play a vital role in the tumor microenvironment and progression of CMS4 colorectal cancer (CRC) metastases. We have performed a comprehensive examination of different neutrophil transcriptional states, through utilization of single-cell RNA sequencing of publicly available and independently generated data across health and malignancy in human and murine disease, and validated findings using in vivo and in vitro models of CMS4 subtype CRC. Methods: Publicly available and independently generated breast, lung and CRC datasets from human disease mouse models were integrated to establish and validate reproducibility of neutrophil-gene signatures, and pseudo-time analysis was used to identify genes driving neutrophil development along a lineage from health to tumor using Seurat on R. Findings were validated in healthy and KrasG12D/+, Trp53fl/fl, Rosa26N1CD/+ (KPN) tumor-bearing wild type or Mrp8CreCxcr2fl/fl genetically engineered mouse models with neutrophil-specific loss of Cxcr2. Results: We have identified distinct neutrophil subtypes in health and primary tumors, preserved in murine and human cancer and across multiple tumor types. In CRC metastases, discrete neutrophil transcriptomic subtypes are identified, with phenotypes from health to those identified in metastases driven by the IL-1β/CXCL8/CXCR2 signalling axis. Assessment of global signalling of single-cell transcripts has identified CD4+ T cells and macrophages as dominant regulators of the metastatic niche. Neutrophils sorted from the metastatic niche strongly suppress T cell proliferation, identifying them as immunosuppressive. Loss of neutrophil-specific Cxcr2 attenuates suppression of T cell proliferation in co-culture with neutrophils from the metastatic niche of tumor-bearing mice. T cell proliferation is unaffected in co-culture with healthy wild type or Cxcr2fl/fl neutrophils. We currently are running orthotopic intrasplenic models to assess the importance of loss of neutrophil-specific Cxcr2 in generation of metastases in vivo in CMS4 CRC. Conclusions: We speculate that ablation of metastasis specific neutrophil subsets in CMS4 CRC in combination with other therapies, may alter the immunosuppressive nature of the immune microenvironment and allow for reduction in tumor burden in metastatic disease. Citation Format: Alistair S. McLaren, Rana Fetit, Mark White, Megan L. Mills, Tamsin Lannagan, John Falconer, Xabier Cortes-Lavaud, Kathryn Gilroy, Rachel Ridgway, Colin Nixon, Varushka Naiker, Renee Njunge, Cassie J. Clarke, Declan Whyte, Kristina Kirschner, Rene Jackstadt, Jim C. Norman, Leo M. Carlin, Andrew D. Campbell, Owen J. Sansom, Colin W. Steele. Single cell RNA sequencing of human and murine cancers demonstrates metastases-specific neutrophil phenotypes driven by the IL-1β/CXCR2 signaling axis - Disruption of this pathway abrogates neutrophil immunosuppressive effects and reduces tumor burden [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6806.

Abstract 4634: Inhibitory-κB kinase alpha as a biomarker and therapeutic target in colorectal cancer

Abstract Introduction/Aims: Colorectal cancer (CRC) remains a leading cause of cancer-related mortality. The canonical NF-κB pathway driven by IKKβ has been implicated in CRC development and progression, however less research has focused on non-canonical NF-κB signaling, regulated by inhibitory-κB kinase alpha (IKKα). This project aimed to assess IKKα, phospho-IKKα (pIKKαs176) and IKKβ expression in a retrospective CRC cohort to establish association with survival outcomes. Subsequently, this project aimed to determine the effect of abrogating IKKα activity without perturbing the canonical NF-κB pathway controlled by IKKβ using a first-in-class selective IKKα inhibitor in vitro/ex vivo. Methods: Immunohistochemical staining for IKKα/pIKKα s176/IKKβ was performed using tissue microarrays from a CRC patient cohort (n=787). QuPath® software was used to semi-quantitively assess expression levels and scores were analyzed for association with cancer-specific survival (CSS). CRC cell lines (n=3), patient-derived organoids (PDOs; n=5) and patient-derived explants (n=5) were treated with novel IKKα inhibitor SU1644 and assessed for cell viability and proliferation. Results: Positive staining for IKKα, pIKKαs176 and IKKβ was detected in tumor specimens. High cytoplasmic expression of IKKα within tumor cells was associated with reduced CSS in patients with right-sided colon cancer (HR=3.091, 95%CI; 1.128-9.467, log rank p=0.021). Conversely, high IKKβ expression was a marker of good prognosis (HR=0.627, 95%CI; 0.457-0.861, log rank p=0.004). A high ratio of IKKα to IKKβ was associated with reduced CSS in the full cohort (HR=1.404, 95%CI; 1.050-1.879, log rank p=0.021) and this was potentiated in right-sided colon cases (HR=1.772, 95%CI; 1.107-2.837, log rank p=0.016). Selective inhibition of IKKα using 1µM SU1644 in vitro caused a significant reduction in HT29 colony formation (p=0.012) and cell viability (p=0.039). PDOs showed altered cell morphology, reduced cell viability and proliferation when treated with SU1644. In the patient-derived explant model, Ki67 expression was reduced in tumor explants treated with SU1644. Conclusions: These data establish high cytoplasmic IKKα expression within tumor cells as a marker of poor prognosis in CRC and conversely high IKKβ expression as a marker of good prognosis. This highlights the importance of development of selective IKKα inhibitor SU1644. IKKα inhibition using SU1644 demonstrated anti-cancer activity in recapitulative CRC disease models. Citation Format: Kathryn A. Pennel, Molly McKenzie, Guang-Yu Lian, Jean A. Quinn, Sara Samir Foad Al-Badran, Campbell S. Roxburgh, Simon P. Mackay, Joanna Birch, Joanne Edwards. Inhibitory-κB kinase alpha as a biomarker and therapeutic target in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4634.

Abstract 7305: Chemoprevention of colorectal cancer: Role of trace minerals in conjunction with calcium

Abstract Background: Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. CRC usually develops from adenomas (CRC precursors) after a long latency period. Prevention is crucial in reducing CRC incidence and progression to cancer. Among several prevention options, calcium has been a widely considered chemo-preventative agent. Aims: Calcium plays a vital role in the regulation of epithelial cell differentiation, which is essential for epithelial growth control. Epidemiological studies have demonstrated that adequate calcium intake is crucial for protection against colonic polyp formation and colorectal cancer. However, recent interventional trials with calcium have had only modest and mixed results, and the question is how to improve efficacy. One potential strategy is to use calcium in combination with additional minerals and trace elements. Results: Our preclinical studies employing monolayer cultures with CRC cell lines and colon organoids cultures from colon polyps have shown that a calcium-rich mineral combination derived from fossilized red algae (Aquamin) is more effective than calcium alone in inducing differentiation, suppressing growth and upregulation of calcium-sensing receptor. When colonic adenomas in culture were subjected to differential proteomic analysis, Aquamin upregulated several proteins involved in proliferation suppression, DNA mismatch repair and inducing differentiation, and apoptosis. Two long-term mouse studies have demonstrated that Aquamin is more effective in suppressing polyp & CRC incidence compared to calcium alone. Based on these findings, we conducted a 90-day FDA-approved trial (a pilot study with ten subjects per arm) comparing the two interventions in human subjects at risk for CRC. Results showed that Aquamin treatment reduced proliferation and increased cell differentiation observed by immunohistochemistry. Proteomic analysis also revealed that the minerals upregulated several proteins related to growth suppression, inducing differentiation and those contributing to cell-cell and cell-matrix adhesion functions and downregulated proteins involved in proliferation and nucleic acid metabolism. Conclusion: These results provide convincing evidence that a multi-mineral combination derived from red algae can provide benefits in preventing CRC that are not seen with calcium alone. Further studies, such as a polyp-prevention trial in human subjects, are warranted to advance these CRC prevention efforts. Citation Format: Isabelle Harber, Shannon McClintock, James Varani, Muhammad N. Aslam. Chemoprevention of colorectal cancer: Role of trace minerals in conjunction with calcium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7305.

Abstract 260: Depletion of Ezh2 in the intestinal adenoma induced by JAK2V617F mutation leads to the malignant neoplasm

Abstract Background The increased JAK2 and EZH2 plays a critical role in the colorectal or colon cancer (CRC) progression. Targeting aberrant JAK2 expression caused by JAK2 gain-of-function (GOF) mutation, JAK2V617F and deregulated EZH2 kinase activity, JAK2 and/or EZH2 inhibitors have been used to treat the advanced CRCs. However, it is unclear whether the aberrant JAK2 can directly induce CRC or intestinal epithelial (IEC) malignancy. We hypothesize that the overexpressed JAK2 driven by JAK2V617F GOF mutation increases IEC neoplasia in which depletion of EZH2 can lead to IEC malignant neoplasm. Materials and Methods Colorectal samples were collected from 20 cases of CRC patients. Immunohistochemistry staining (IH), confocal immunofluorescence staining (IF) and bulk RNAseq were used to determine LGR5, Ki67, JAK2, EZH2, mutant β-catenin and JAK2V617F GOF mutation. Crypt-derived organoids or tumoroids were used to determine the JAK2 and EZH2 in the proliferative LGR5 cells (Ki67hiLGR5+) and were treated with JAK2 and/or EZH2 inhibitors. The mice with JAK2 and/or EZH2 deficiency in IECs were generated by crossing VilCreER mice, floxed-Jak2 and/or floxed-Ezh2 mice to determine the intestinal and colonic neoplasia. Lgr5, Ki67, Cdx2 Jak2, Ezh2, and mutant β-catenin IH or IF, organoids culture and peritoneal xenograft were used to determine the malignant neoplasm. The JAK2V617F-transfected HT29 or Caco-2 cells were used to determine the migration induced by JAK2V617F GOF mutation, then treated with EZH2 inhibitors to determine the effects of EZH2 inhibition on JAK2V617F GOF mutation-induced migration. The spheres were formed with Caco-cells with JAK2V617F GOF mutation and were used to observe the effects of JAK2V617F GOF mutation on IEC neoplasia formation. Results JAK2 and/or EZH2 overexpression are positively correlated with the probability of CRC initiation. JAK2 and EZH2 are highly expressed in the CRC tumoroids. Inhibition of EZH2 increases the CRC tumoroids growth and spheroid formation, and reduces budding numbers while reducing the proliferation of organoids from healthy crypts. Jak2 over-expression in IECs increases intestinal microadenoma, and depletion of EZH2 in the adenoma increases mutant β-catenin and severity of intestinal adenoma, suggesting that depletion of EZH2 enhances the malignancy of overexpressed Jak2-derived IEC neoplasia. Consistently, JAK2V617F GOF mutation increases HT29 or Caco-2 cell migration. Conclusion JAK2V617F GOF mutation can drive IEC neoplastic proliferation and adenoma, depletion of EZH2 in the adenoma leads to IEC malignant neoplasm. Our research suggests that loss of Ezh2 may synergistically cooperate with the Jak2V617F mutation in the pathogenesis of IEC malignant neoplasm. Citation Format: Nardana Esmaeili, Ahmed Bakheet, Wen Gao, Haifeng Li, Dan Cai, Xiaonan Han. Depletion of Ezh2 in the intestinal adenoma induced by JAK2V617F mutation leads to the malignant neoplasm [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 260.

Abstract 4428: Integrated multi-omics analysis reveals systemic and localized metabolic disruptions in colorectal cancer

Abstract Despite technological advances in molecular medicine over the last 30 years, no single approach has proven to be sufficient to meet the diagnostic needs in cancer care. Here we use a multiomic approach leveraging proteomic, metabolomic, and transcriptomic technologies to study the metabolic shifts that occur during colorectal cancer (CRC) progression, Our integrated analysis identified systemic changes to beta oxidation pathways and localized changes to tyrosine metabolism within the tumor, creating a mechanistic, actionable description of the core CRC metabolic program. We conducted untargeted proteomics and metabolomics profiling on serum samples from CRC patients (n=10) and healthy controls (n=10). Our serum proteomics data is generated through sample enrichment on the Seer Proteograph system followed by LC/MS analysis with the Thermo Orbitrap Astral. Our metabolomics approach employs LC/MS assays for unbiased profiling of the serum metabolome, exposome, and lipidome. We supplemented this discovery work with both targeted serum and tumor-specific approaches including targeted proteomics to quantify select targets, inflammatory profiling with Alamar proteomics, public transcriptomics data from TCGA, and in vitro metabolic flux data. These large and diverse datasets were then integrated through joint pathway analysis and network integration. The global serum proteomics and metabolomics profiles generated show distinct separation between healthy and diseased individuals. Joint pathway analysis of these discovery datasets highlighted enrichment in beta oxidation pathways and tyrosine metabolism, among others. Interestingly, the Alamar inflammatory panel revealed that many of the analytes in the tyrosine metabolism pathway were well correlated with inflammatory status, while the beta oxidation signature had a lower correlation. To determine the relationship of these systemic findings from serum to tumor metabolism itself, we integrated tumor-specific transcriptomics data and found alterations to tyrosine metabolism with differences in tyrosine aminotransferase expression. The beta oxidation related genes, on the other hand, were not concordant with the serum findings. However, our in vitro metabolic flux studies have shown beta oxidation in CRC cells is upregulated to provide additional fuel for oxidative phosphorylation. This result suggests that beta oxidation may not be transcriptionally regulated in the tumor but rather a consequence of organismal metabolic rewiring. The results of this work, which is currently expanding into a larger and more diverse patient population, underscores the power of multiomic profiling for enhancing our understanding of metabolic dysregulation in CRC. Ultimately, a comprehensive model of the molecular alterations in CRC will yield a better understanding of tumor phenotypes and inform better diagnostics and therapies. Citation Format: Gary Patti, Ethan Stancliffe, Adam Richardson, Ashima Mehta, Monil Gandhi, Kevin Cho. Integrated multi-omics analysis reveals systemic and localized metabolic disruptions in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4428.

Abstract 1688: Nuclear receptor coactivator SRC-1 promotes colorectal cancer immune escape by enhancing PD-L1 transcription and protein stability

Abstract Programmed death-ligand 1 (PD-L1), one of the immunosuppressive molecules, overexpresses in multiple cancers and is critical for their immune escape. We previously showed that the nuclear coactivator SRC-1 promoted colorectal cancer (CRC) progression by enhancing CRC cell viability; however, the role of SRC-1 in CRC immune escape is unclear. Here, we demonstrated that SRC-1 was positively correlated with PD-L1 in human CRC specimens. SRC-1 deficiency significantly inhibited PD-L1 expression in both human and murine CRC cells and retarded murine CRC growth in subcutaneous grafts by enhancing CRC immune escape via increasing tumor infiltration and antitumor activity of effector CD8+ T cells. Genetic ablation of SRC-1 in mice also decreased PD-L1 expression in AOM/DSS-induced murine CRC. These results suggest that tumor-derived SRC-1 promotes CRC immune escape by enhancing PD-L1 expression. Mechanistically, SRC-1 activated JAK-STAT signaling by inhibiting SOCS1 expression and coactivated STAT3 and IRF1 to enhance PD-L1 transcription as well as stabilized PD-L1 protein by inhibiting proteasome-dependent degradation mediated by speckle type POZ protein (SPOP). Pharmacological inhibition of SRC-1 improved the antitumor effect of PD-L1 antibody in both subcutaneous graft and AOM/DSS-induced murine CRC models. Taken together, our findings highlight a crucial role of SRC-1 in facilitating CRC immune escape and targeting SRC-1 in combination with PD-L1 antibody immunotherapy may be an attractive strategy for CRC treatment. Citation Format: Yilin Hong, Qiang Chen, Zinan Wang, Yong Zhang, Bei Li, Xu Kong, Pingli Mo, Nengming Xiao, Jianming Xu, Yunbin Ye, Chundong Yu. Nuclear receptor coactivator SRC-1 promotes colorectal cancer immune escape by enhancing PD-L1 transcription and protein stability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1688.

Abstract 603: BB5523, a multiple kinase inhibitor with HPK1, VEGFR2 and TNIK inhibition, enhanced antitumor immunity in tumor models

Abstract Introduction: Immuno-suppressive micro-environment and abnormal signaling pathways are crucial for the proliferation of tumor cells. Hematopoietic progenitor kinase 1 (HPK1) inhibitor plays important roles in activation of exhausted T cells and enhancement of anti-tumor immune responses. VEGF/VEGFR2 pathway is the central therapeutic target in anti-angiogenic treatment in multiple cancers. Traf2- and Nck-interacting kinase (TNIK) is a member of the germinal center kinase family, and is reported to be essential for Wnt signaling and colorectal cancer (CRC) proliferation and progression. Blockade of critical kinases in multiple signaling pathways inhibits the proliferation, invasion and metastasis of cancer cells. Therefore, intergradation of these functions in a small molecule serves as the next generation of immune-oncology small molecules for cancer therapy. Methods: BB5523 was developed through structure-based drug design, and optimized by SAR analysis and medicinal chemistry iteration. Biochemical assays and cell-base functional assays were applied in compound evaluation. Pharmacokinetic (PK) and preliminary toxicity studies were performed with mice. CDX and syngeneic tumor models in mice were conducted to evaluate the in vivo efficacy of BB5523 as a single agent. Results: BB5523 shows high inhibition potency on HPK1 with good selectivity against other TCR signaling-related kinases, such as FYN and ZAP70. Inhibition of HPK1 kinase activity (IC50 = 3.3 nM) by BB5523 strongly suppresses the phosphorylation of the downstream biomarker protein SLP-76 (IC50 = 30 nM); and boosts the IL-2 secretion in purified human T cells and human peripheral blood mononuclear cells. BB5523 also shows good activities on VEGFR2 (IC50 = 1.6 nM) and TNIK (IC50 = 0.7 nM) which are crucial for the proliferation of cancer cells. In in vitro experiments, BB5523 significantly inhibits the proliferation of various tumor cell lines at sub-micromolar concentrations. PK profile of BB5523 shows good oral bioavailability (F > 80%). In preliminary safety evaluation, no abnormal symptoms were observed in mice dosed up to 100 mpk for 14 days. BB5523 showed significant tumor-growth inhibition efficacy in TE-8, JIMT-1, B16-F10 and MC38 tumor models. Conclusion: As a potent and oral available small molecule kinase inhibitor, BB5523 boosts anti-tumor immunity through HPK1 inhibition, while also blocking crucial signaling pathways in tumor micro-environment. BB5523 shows promising in vitro and in vivo efficacy with a well-tolerated safety profile. The preclinical study of BB5523 is in progress. Citation Format: Gongping Duan, Min Li, Puyong Zhang, Wei Hua, Enlun Hao, Shipeng Wang, Xiaoyi Ma, Junheng Wang, Lijie Wei, Xingmin Zhang. BB5523, a multiple kinase inhibitor with HPK1, VEGFR2 and TNIK inhibition, enhanced antitumor immunity in tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 603.

Abstract 1478: Chronic perfluorooctanesulfonic acid exposure promotes proliferation of colorectal cancer cells

Abstract Background: Chronic exposure to long-term exposures to per- and polyfluoroalkyl substances (PFAS), widely known as “forever chemicals”, has been associated with multiple negative health outcomes including increased risk of cancer. Perfluorooctanesulfonic acid (PFOS), a “long-chain” subtype of PFAS, has high bioaccumulation potential with a long elimination half-life. PFOS is frequently detected in drinking water leading to its high absorption through the gastrointestinal tract. Recent studies demonstrate that PFAS exposures promote intestinal inflammation and gut barrier dysfunction. However, how a long-term PFOS exposure affects colorectal cancer (CRC) progression is not known. Therefore, the purpose of this study is to delineate the effect of PFOS exposure on CRC cell proliferation and test the potential mitigation strategy for the harmful effects of PFOS. Methods: SW480 and HCT116 cells have been treated with 1 ug/mL PFOS and proliferation was measured at 1, 2, and 3 months using the Presto Blue Cell Viability Reagent fluorescence assay. Proliferation markers were assessed by qPCR and Western blot. Control and PFOS exposed cells were treated with sulforaphane, a nuclear factor erythroid 2-related factor 2 (Nrf-2) inducer, at concentration 5, 10 and 20 uM for 72 hours. Results: We show that chronic, low-dose PFOS exposure promotes proliferation of SW480 and HCT116 cell lines starting at 3 months since the first exposure. The increase in proliferation is associated with upregulation of Cyclin D, pAkt and FASN. We also show that sulforaphane significantly decreases proliferation of HCT116 and SW480 cells, and its efficacy is significantly higher in PFOS exposed CRC cells. The current studies show no effect on sulforaphane on normal colon epithelium cells. Conclusion: Our studies suggest that chronic PFOS exposure promotes proliferation of CRC cells by increasing pro-carcinogenic gene expression and signaling. Furthermore, our findings suggest that supplementation of diet sulforaphane can potentially mitigate the harmful effects from PFOS exposure. Our studies warrant further investigation of the mechanisms behind the effect of PFOS exposure on cancer progression that would guide development of effective intervention strategies to mitigate the harmful effects of the exposure to “forever chemicals”. Citation Format: Jerika Durham, Josiane Weber Tessmann, Bernhard Hennig, Yekaterina Zaytseva. Chronic perfluorooctanesulfonic acid exposure promotes proliferation of colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1478.

Abstract 6683: The abundance of Fusobacteria nucleatum in tumor tissue is a prognostic factor in patients of right-sided colorectal cancer

Abstract Background: A significant association between the gut microbiome and colorectal carcinogenesis, as well as cancer progression. It has been reported that Fusobacteria nucleatum (F. nucleatum) is one of the most famous bacteria associated with colorectal cancer (CRC). It has been reported that the abundance of F. nucleatum is associated with colorectal cancer-specific survival (CSS), however it remains unclear for association with F. nulceatum and relapse-free survival (RFS). If F. nucleatum has a significant involvement in tumor progression of colorectal cancer, the abundance of F. nucleatum should be associated with not only CSS but also RFS in colorectal cancer. In this study, we measured the bacterial mass of F. nucleatum in tumor tissue of CRC patients in Stage II-III to explore the differences in prognosis. Methods: We included patients with CRC in stage II-III who underwent surgical treatment at Nippon Medical School Hospital between January 2017 and December 2020 except patients who received preoperative chemoradiotherapy and had multiple cancers. We measured the absolute of F. nucleatum copy number of the DNA exacted tumor tissues using droplet digital PCR. Results: 253 patients with CRC were included. 128 patients had pathological stage II and 125 patients had pathological stage III. Among 253 patients, 104 patients had right-sided CRC, 89 patients had left-sided, and 60 patients had rectal cancer. F. nucleatum was detected in 166 patients (65.6%), and the median of F. nucleatum copy number was 1.08 (range; 0.00 -2791.3). F. nucleatum copy number was more abundant in right-sided CRC than in left-sided and rectal cancer (p= 0.02, p=0.01). There was no significant difference between stage II CRC and stage III. We categorized patients into two groups based on the median cut point of F. nucleatum copy number: the F. nucleatum-high group and the F. nucleatum-low group for comparison with clinicopathological features and prognosis. Patients with high abundance of F. nucleatum exhibited T4 of tumor depth (p=0.03), right-sided CRC (p=0.01), longer tumor circumference (p <0.001), longer tumor length (p <0.001), and no lymph node metastasis (p=0.024). There was no significant difference in relapse-free survival between the F. nucleatum-high group and F. nucleatum-low group among whole patients (p=0.53). Analyzing divided tumor location, in right-sided CRC high abundance of F. nucleatum was significantly associated with shorter relapse-free survival than low abundance (p=0.02), while in left-sided and rectal cancer there was no significant difference (p=0.61). Conclusion: F. nucleatum was more abundant in right-sided CRC and associated with relapse-free survival only in right-sided CRC. F. nucleatum may make a greater impact on right-sided CRC than on left-sided and rectal cancer. Citation Format: Toshimitsu Miyasaka, Takeshi Yamada, Sho Kuriyama, Akihisa Matsuda, Kay Uehara, Seiichi Shinji, Yasuyuki Yokoyama, Goro Takahashi, Takuma Iwai, Kohki Takeda, Shintaro Kanaka, Hiroshi Yoshida. The abundance of Fusobacteria nucleatum in tumor tissue is a prognostic factor in patients of right-sided colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6683.

Abstract 1519: Effect of obesity on CD4+ T cells in the tumor immune microenvironment of colorectal cancer

Abstract Background: The number of new cases and deaths from colorectal cancer (CRC) is increasing rapidly, and obesity is considered one of the risk factors. Obesity-associated cancers are related to the overproduction of hormones, induction of reactive oxygen species (ROS) production by free fatty acids, and changes in the gut microbiome. Obesity also promotes immune cell dysfunction in the tumor immune microenvironment (TIME). The increase of fatty acid levels due to obesity causes metabolic reprogramming and decreases the cytotoxic activity of natural killer (NK) cells and CD8+ T cells, which accelerate tumor progression. However, the impact of obesity on CD4+ T cells in the TIME remains unclear. Therefore, this study aimed to clarify how obesity affected the number and the anti-tumor activity of CD4+ T cells in CRC using mouse models. Methods: Seven-week-old male C57BL/6J mice were randomly divided into two groups and fed the control diet (CD) or high-fat diet (HFD) for nine weeks. Blood samples were collected from the buccal vein of the mice every four weeks after feeding for analysis. MC38 CRC cells of 4 × 106 were subcutaneously inoculated in the middle of the backs of mice to analyze tumor progression. Three weeks after tumor cell inoculation, the mice were sacrificed, and the immune cells of the tumor, blood, and various organs were analyzed. Results: After nine weeks of feeding, the HFD-fed mice had a significantly increased body weight compared to CD-fed mice. Flow cytometry results revealed that the number and frequency of CD4+ T cells in the blood were significantly reduced in HFD-fed mice compared to those in CD-fed mice, and the expression of programmed death-1 (PD-1) in CD4+ T cells in HFD-fed mice was significantly higher than that in CD-fed mice at eight weeks. Three weeks after tumor inoculation, HFD feeding accelerated tumor growth and decreased the survival rate. The number of CD4+ T cells in the tumors was significantly reduced in HFD-fed mice compared to that in CD-fed mice (55.9 vs 18.2 cells/mg; 95% CI 14.9-60.3 cells/mg; P = 0.006). The number of CD8+ T cells in the tumors was also reduced, which was more pronounced for CD4+ T cells than for CD8+ T cells. In addition, the production of cytokines such as IFN-γ and TNF-α was significantly reduced in CD4+ T cells and CD8+ T cells of HFD-fed mice. In a depletion analysis of CD4+ T cells, the feeding-dependent acceleration of tumor growth was not observed in each group. This result indicated that CD4+ T cells were involved in accelerating tumor growth due to HFD-induced obesity. Conclusion: We showed that the reduced number and dysfunction of CD4+ T cells due to obesity led to a decreased anti-tumor response of both CD4+ and CD8+ T cells, ultimately accelerating the progression of colorectal cancer. Our findings may elucidate the pathogenesis for poor outcomes of colorectal cancer associated with obesity. Citation Format: Masayuki Ando, Kota Yamada, Masafumi Saito, Kimihiro Yamashita, Takao Tsuneki, Yuri Adachi, Tomoki Abe, Tomosuke Mukoyama, Ryuichiro Sawada, Yasufumi Koterazawa, Hitoshi Harada, Naoki Urakawa, Hironobu Goto, Hiroshi Hasegawa, Shingo Kanaji, Takeru Matsuda, Yoshihiro Kakeji. Effect of obesity on CD4+ T cells in the tumor immune microenvironment of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1519.

Abstract 3790: HtrA3 promotes malignant progression of colorectal cancer via PI3K-AKT-FOXO1 signaling pathway

Abstract High-temperature requirement protease A3 (HtrA3) is known to contribute to the progression of various carcinomas through tissue-specific actions, yet its precise role in colorectal cancer (CRC) remains unclear. Our study revealed that HtrA3 is significantly upregulated in CRC at both mRNA and protein levels. TCGA database analysis showed that higher HtrA3 expression in colon adenocarcinoma is linked to poorer patient survival. Moreover, increased HtrA3 expression in HCT116 cells boosted their proliferation, migration, and invasion, while decreasing HtrA3 in SW480 cells had the reverse effect. In HCT116 cells with high HtrA3 levels, there was an increase in p-PI3K, p-AKT, and p-FOXO1, which reduced upon treatment with the PI3K inhibitor LY294002. Conversely, in SW480 cells with lowered HtrA3, these molecular levels decreased and rose again after treatment with the PI3K activator 740Y-P. HtrA3 also promoted cell proliferation, migration, and invasion in the presence of LY294002 and 740Y-P. In vivo experiments demonstrated that HtrA3 overexpression accelerated xenograft tumor growth. This study confirms that HtrA3’s overexpression in CRC cells promotes their proliferation, migration, and invasion by activating the PI3K-AKT-FOXO1 signaling pathway. Therefore, HtrA3 could be a significant factor in the advancement of CRC and may serve as a potential prognostic marker for guiding targeted CRC therapies. Citation Format: Jing Zheng, Xianhua Huang, Xian-e Peng, Yunli Wu. HtrA3 promotes malignant progression of colorectal cancer via PI3K-AKT-FOXO1 signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3790.

Abstract 4339: Chromatin landscapes of colorectal cancer development and cfDNA fragmentation

Abstract Introduction: The stepwise progression of colorectal cancer from healthy epithelium, to premalignant adenoma, to cancer is accompanied by genome-wide epigenetic reprogramming. However, current analyses of these processes have been hampered by complex mixtures of cells in normal, adenoma and cancer tissue samples, as well as absence of suitable adenoma model systems. Cultured colorectal organoids, comprised of pure epithelial cells, could enable insights on the epigenetic changes leading to progression from healthy tissue to cancer. Methods: Using 43 patient-derived colorectal organoids derived from healthy, adenoma, and cancer tissues, we examined the chromatin landscape of tumor progression using transposase accessible chromatin analyses with next generation sequencing. We defined a consensus set of nucleosome depleted regions for each disease stage and used principal component analyses to identify peaks that contributed the most variation across the collection of organoids. Consensus regions were linked to genes they overlapped, and intergenic consensus regions were linked to the nearest gene within 1 Mbp. Subsequently, we performed a gene set enrichment analysis to assess pathways affected by differential chromatin accessibility. To identify the transcription factor drivers of regulatory reprogramming, the DNA sequences within the consensus peaks were analyzed for enrichment of characteristic binding motifs. We analyzed regions of consensus peaks for fragmentation characteristics in the circulating cell-free DNA (cfDNA) of 250 healthy individuals and 51 patients with stage IV colorectal cancer. Results: Across all organoid samples, we identified >35 million nucleosome depleted regions that we coalesced into a consensus set of 61,755 regions. We excluded 13,040 regions that had low variation across the organoid tissues, leaving 48,715 regions that could potentially define tissue-specific signatures of chromatin accessibility. As 78% of these regions could be linked to genes, we assessed whether these signatures identify known pathways involved in colorectal cancer. We identified unique signatures of healthy tissues, adenomas, and cancers comprising genes of known and novel pathways, including those involved in WNT, hippo, and RAS signaling. We found that changes in chromatin accessibility can be detected in circulating cfDNA profiles and were associated with independent circulating tumor DNA abundance by droplet digital PCR (R=0.78, p<0.0001). Conclusions: These analyses highlight important targets of chromatin remodeling in colorectal tumorigenesis and provide an avenue for evaluating these through genome-wide analyses of cfDNA fragmentation. Citation Format: Nicholas A. Vulpescu, Zachariah H. Foda, Pieter H. Wisse, Jamie E. Medina, Vilmos Adleff, Remond J. Fijneman, Robert B. Scharpf, Gerrit A. Meijer, Beatriz Carvalho, Victor E. Velculescu. Chromatin landscapes of colorectal cancer development and cfDNA fragmentation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4339.

Overexpression of circular RNA hsa_circ_0008621 facilitates colorectal cancer progression and predicts poor prognosis.

To evaluate the potential role of serum and tissue hsa_circ_0008621 as a prognostic biomarker for CRC patients. Focused on the functional role of hsa_circ_0008621 in colorectal cancer (CRC). Serum and tissue hsa_circ_0008621 expression were quantified by qRT-PCR in 157 CRC patients, as well as 100 serums from healthy controls. Serum and tissue hsa_circ_0008621 expression was evaluated for their prognostic role in CRC patients using Kaplan-Meier curves and Multivariate Cox proportional hazards analysis. To further characterize the biological role of hsa_circ_0008621 expression in CRC, invitro hsa_circ_0008621 inhibition was performed and the effects on cellular growth, migration, invasion, apoptosis, and glycolysis were explored. Next, the downstream molecules for hsa_circ_0008621 were predicted. Hsa_circ_0008621 expression was significantly upregulated in CRC tissues and serums. Serum hsa_circ_0008621 levels were significantly up-regulated in advanced-staged samples. High serum hsa_circ_0008621 expression was associated with shorter overall survival and recurrence-free survival in CRC patients. Multivariate Cox regression analysis identified a high level of serum hsa_circ_0008621 expression as an independent prognostic factor with respect to overall survival and recurrence-free survival. Loss of function assays for hsa_circ_0008621 invitro led to a significant decrease in cell proliferation, migration, invasion, and glycolysis, but an increase in cell apoptosis. Hsa_circ_0008621 can sponge miR-532-5p, which targets SLC16A3. High level of serum hsa_circ_0008621 is associated with poor survival in CRC and promotes CRC progression, suggesting it to be a promising non-invasive prognostic biomarker and novel therapeutic target in CRC patients.

Bifidobacterium longum suppresses colorectal cancer through the modulation of intestinal microbes and immune function.

Colorectal cancer (CRC), one of the most common malignancies in the world, urgently requires more treatment strategies. Although there has been much research on probiotics, limited research has been done in treating cancer. The purpose of this study was to investigate the role of Bifidobacterium longum (B. longum) in the prevention and treatment of CRC. Through Cell Counting Kit-8 and Colony Formation Assays, 8 h and a B. longum count of 1 × 108 CFU/ml were chosen as the best cocultivation conditions with CRC cells. The role of B. longum in inhibiting the progression of CRC cells was verified by a series of functional and immunofluorescence assays. For instance, in vivo assays have verified that B. longum could alleviate CRC progression. In addition, according to the results of in vivo assays and clinical statistical analysis, B. longum could reduce diarrhea symptoms. Mechanistically, by 16S and RNA sequencing, it was found that B. longum could affect the development of CRC by regulating the composition of gut microbes and enhancing immune function. The B. longum might inhibit the occurrence and development of CRC and relieve diarrhea symptoms by regulating intestinal microbes and immune function.

Abstract 4125: Exploring the efficacy of alpelisib and combined PI3Kα-S6K inhibition in LIN28B-mediated colorectal cancer metastasis

Abstract Introduction: Colorectal cancer (CRC) is the third most diagnosed cancer worldwide. LIN28B, an RNA-binding protein that regulates mRNA translation, has garnered significant interest in recent cancer research. Our lab has established that LIN28B is an oncogene and promotes CRC metastasis. However, the exact mechanisms through which LIN28B exerts these effects remain elusive. The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is altered in 50-70% of CRCs and is characterized by PIK3CA gene mutations in 20-30% of CRC cases. PIK3CA encodes the catalytic subunit p110α of the PI3Kα enzyme, which is critical for PI3K/AKT signaling. Activation of this pathway is associated with worse CRC prognosis. Among the components of this signaling cascade, the ribosomal protein S6 kinase (S6K) is a crucial downstream effector, playing a pivotal role in protein synthesis and cell growth. Despite the frequent occurrence of PIK3CA mutations in CRC, targeted therapies for PIK3CA-mutant CRC are lacking. Alpelisib, a PI3Kα-specific inhibitor approved by the FDA for a subset of PIK3CA-mutant breast cancers, remains largely unassessed in CRC. We hypothesize that LIN28B-mediated CRC metastasis is facilitated by the activation of the PI3K/AKT pathway, representing a potential target for Alpelisib or other related inhibitors. Results: Our data indicate that LIN28B expression in CRC cells promotes liver metastasis in mouse models of metastatic CRC (mCRC). Furthermore, LIN28B expression activates the PI3K/AKT pathway, as measured by an AKT phosphorylation array. Treatment of CRC cells with SC79, a pan-AKT activator, enhanced cell migration and invasiveness. Similarly, VillinCre;R26Pik3ca transgenic mice, expressing a constantly active mutant form of PI3Kα in the intestinal epithelium, demonstrated crypt hyperplasia and an amplified propensity for tumorigenesis, mirroring the effects of LIN28B expression in CRC. Importantly, Alpelisib effectively hinders LIN28B-driven CRC progression in cell lines, transgenic mice-derived organoids, and mCRC mouse models, as well as the growth rate of CRC patient-derived organoids (PDOs). The effects observed with Alpelisib treatment were replicated with inhibition of S6K using either LY25284702 or PF4708671. Moreover, a combination of low-dose Alpelisib with low-dose LY25284702 or PF4708671 synergistically restricted the growth of PDOs. Conclusion: Our data provide compelling evidence that the PI3K/AKT pathway regulates LIN28B-mediated CRC metastasis, and its inhibition by Alpelisib is feasible. This underscores the potential for precision medicine in CRC, offering targeted therapies to PIK3CA-mutant CRC patients who lack specific treatment options. Furthermore, our study highlights the clinical advantages of combined inhibition strategies for improved anti-metastatic outcomes, a field in dire need of interventions in mCRC. Citation Format: Alice E. Shin, Kensuke Sugiura, Secunda W. Kariuki, David A. Cohen, Christopher J. Lengner, Peter A. Sims, Joel T. Gabre, Anil K. Rustgi. Exploring the efficacy of alpelisib and combined PI3Kα-S6K inhibition in LIN28B-mediated colorectal cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4125.