Human CRC Research Articles

MiR-195-5p Inhibits Colon Cancer Progression via KRT23 Regulation

Background/Objectives: KRT23 was recently discovered as an epithelial-specific intermediate filament protein in the type I keratin family. Many studies have underlined keratin’s involvement in several biological processes as well as in the pathogenesis of different diseases. Specifically, KRT23 was reported to affect the structural integrity of epithelial cells and to trigger cellular signaling leading to the onset of cancer. The aim of this study is to characterize a novel mechanism based on miR-195-5p/KRT23 in colorectal cancer. Methods: KRT23 mRNA and protein expression were characterized in FFPE sections from patients with CRC. The effects of miR-195-5p on KRT23 expression at the mRNA and protein levels were assessed by transient transfection experiments with mimic and inhibitor molecules. Cell attachment/detachment, migration, invasion, clone formation, and apoptosis were evaluated in human CRC cell lines after miR-195-5p mimic transfection. Results: We identified KRT23 as a putative target of miR-195-5p, a microRNA that we previously demonstrated to be reduced in CRC. We have proved the KRT23 expression deregulation in the tumoral section compared to adjacent normal mucosa in patients with CRC, according to the data derived from the public repository. We proved that the gain of miR-195-5p decreased the KRT23 expression. Conversely, we demonstrated that the inhibition of miR-195-5p led to an increase in KRT23 expression levels. We have demonstrated the in vitro effectiveness of miR-195-5p on CRC progression and that the in vivo intraperitoneal delivery of miR-195-5p mimic lowered colonic KRT23 mRNA and protein expression. Conclusions: These findings highlight a new regulatory mechanism by miR-195-5p in CRC affecting the keratin intermediate filaments and underline the miR-195-5p potential clinical properties.

Gingerenone A induces ferroptosis in colorectal cancer via targeting suppression of SLC7A11 signaling pathway

BackgroundColorectal cancer (CRC) is one of the most common and fatal diseases, yet effective therapeutic drugs are lacking in clinical settings. Gingerenone A (GA) is an active compound derived from ginger, has demonstrated anti-tumor properties. However, the efficacy of GA against CRC and its primary mechanism of action remain unclear. Materials and methodsMTT assay and colony formation assay were employed to evaluate cell viability. Transwell assays were utilized to assess the migratory and invasive capabilities of the cells. The effects of GA on ferroptosis related proteins were analyzed using Western blot. Levels of glutathione (GSH), malondialdehyde (MDA), Fe2+, and 4-hydroxynonenal (4-HNE) levels were measured with a biochemical index determination kit. Cellular reactive oxygen species (ROS) were quantified using flow cytometry. CETSA, pull-down, and co-immunoprecipitation (Co-IP) assays confirmed the interactions between GA and SLC7A11, as well as the ubiquitination promoted by SLC7A11. A xenograft mouse model was employed to validate the anticancer effect of GA in vivo. ResultsWe observed that GA significantly suppressed proliferation in human CRC cells. Additionally, GA treatment inhibited the migration, invasion, and colony formation of CRC cells. Subsequently, through the use of specific inhibitors, we discovered that the suppression of CRC cells by GA was dependent on ferroptosis rather than autophagy or apoptosis. Previous research has demonstrated that GA treatment significantly triggers ferroptosis. Mechanistically, GA treatment promotes the degradation of the SLC7A11 protein, which plays a crucial role in ferroptosis. Notably, the knockdown of SLC7A11 abolished the detrimental effects of GA on the proliferation of CRC cells and reversed GA-induced ferroptosis in CRC cells both in vivo and in vitro. Further research has shown that GA can directly bind to the SLC7A11 protein and promote its ubiquitination. ConclusionOur research provides compelling evidence that GA may serve as a potential agent for suppressing the progression of CRC by inducing ferroptosis and promoting the ubiquitination and degradation of SLC7A11.

P53 genotype-independent anticancer effects of olibanum extract and 11-keto-beta-boswellic acid on human colorectal cancer cells

BackgroundColorectal cancer (CRC) is the third most common cancer, and CRC-related mortality is increasing annually. A key regulator of the cell cycle and cell death, the p53 gene, is frequently found in patients with CRC as mutants. Since tumors with abnormal p53 sometimes show resistance to anticancer drugs, it is important to develop anticancer drugs according to genetic characteristics. Although evidence shows that boswellic acids (BAs) might be potential anticancer agents, the anticancer effects and mechanisms involved in their activities in CRC are unclear. Methods and ResultsHere, we investigated whether olibanum (Boswellia serrata Roxb.) extract and 11-keto-β-boswellic acid exerted cytotoxic effects against p53 wildtype, p53 mutated-, and p53-deleted human CRC cell lines. Results show that 11-keto-β-boswellic acid considerably reduced cell viability and induced cell cycle arrest in HCT116, HT29, and SW1417 cells. And increase of apoptotic cell population and morphological changes in apoptotic cells induced by 11-keto-β-boswellic acid were observed. The 11-keto-β-boswellic acid mediated cell cycle arrest and apoptosis were accompanied by changes in the expression of factors linked to apoptosis, regardless of p53 genotype. In addition, 11-keto-β-boswellic acid-treated cells dissociated from their spheroidal structure and appeared in an irregular form. ConclusionsAlthough further investigations are required to fully understand the underlying mechanisms, these results may provide insight into the potential of using olibanum extract and 11-keto-β-boswellic acid as therapeutic agents, with no difference in sensitivity depending on the p53 genotype.

Targeting circ-0034880-enriched tumor extracellular vesicles to impede SPP1highCD206+ pro-tumor macrophages mediated pre-metastatic niche formation in colorectal cancer liver metastasis

BackgroundInformation transmission between primary tumor cells and immunocytes or stromal cells in distal organs is a critical factor in the formation of pre-metastatic niche (PMN). Understanding this mechanism is essential for developing effective therapeutic strategy against tumor metastasis. Our study aims to prove the hypothesis that circ-0034880-enriched tumor-derived extracellular vesicles (TEVs) mediate the formation of PMN and colorectal cancer liver metastasis (CRLM), and targeting circ-0034880-enriched TEVs might be an effective therapeutic strategy against PMN formation and CRLM.MethodsWe utilized qPCR and FISH to measure circRNAs expression levels in human CRC plasma, primary CRC tissues, and liver metastatic tissues. Additionally, we employed immunofluorescence, RNA sequencing, and in vivo experiments to assess the effect mechanism of circ-0034880-enriched TEVs on PMN formation and CRC metastasis. DARTS, CETSA and computational docking modeling were applied to explore the pharmacological effects of Ginsenoside Rb1 in impeding PMN formation.ResultsWe found that circ-0034880 was highly enriched in plasma extracellular vesicles (EVs) derived from CRC patients and closely associated with CRLM. Functionally, circ-0034880-enriched TEVs entered the liver tissues and were absorbed by macrophages in the liver through bloodstream. Mechanically, TEVs-released circ-0034880 enhanced the activation of SPP1highCD206+ pro-tumor macrophages, reshaping the metastasis-supportive host stromal microenvironment and promoting overt metastasis. Importantly, our mechanistic findings led us to discover that the natural product Ginsenoside Rb1 impeded the activation of SPP1highCD206+ pro-tumor macrophages by reducing circ-0034880 biogenesis, thereby suppressing PMN formation and inhibiting CRLM.ConclusionsCirc-0034880-enriched TEVs facilitate strong interaction between primary tumor cells and SPP1highCD206+ pro-tumor macrophages, promoting PMN formation and CRLM. These findings suggest the potential of using Ginsenoside Rb1 as an alternative therapeutic agent to reshape PMN formation and prevent CRLM.

MiRNAs: possible regulators of toll like receptors and inflammatory tumor microenvironment in colorectal cancer

BackgroundColorectal cancer (CRC) is ranked as the third most commonly diagnosed cancer and the third cause of cancer related deaths. CRC is greatly attributed to genetic and epigenetic mutations and immune dysregulation. Tumor aberrant expression of Toll-like Receptors (TLRs) can contribute to tumorigenesis. Recent studies suggested that microRNAs act as direct ligands of TLRs altering their expression and signaling pathways.AimTo prove our concept that specific miRNA mimics may act as antagonists of their specific toll like receptors inhibiting their expression that could limit the release of pro-inflammatory and pro-tumorigenic cytokines leading to apoptosis of tumor cells.MethodsFrom public microarray databases, we retrieved TLRs and miRNAs related to CRC followed by in silico docking of the selected miRNA ligands into the TLRs. Clinical validation after co-immunoprecipitation of TLRs and their interacting miRNA ligands was done. Expression of TLRs 1, 7,8 was determined by ELISA while miRNAs was measured by RT-qPCR. In addition, microRNA mimics of the down regulated miRNAs were transfected into human CRC cell lines.ResultsOur data demonstrate that TLRs 1, 7, 8 are up regulated in CRC compared to controls. Further, three miRNAs (-122, -29b and -15b) are relatively downregulated, while 4 miRNAs (-202, miRNA-98, -21 and -let7i) are upregulated in CRC patients compared to those with benign tumor and healthy controls. Transfection of down regulated miRNA mimics into CRC cell lines resulted in a significant reduction of the number and viability of cells as well as down regulating the expression of TLRs 1, 7 and 8 with ultimate reduction of downstream effector IL6 protein, suggesting that these miRNAs are negative regulators of carcinogenesis.ConclusionMicroRNAs could act as antagonistic ligands of TLRs limiting the inflammatory tumor microenvironment.

Zosterabisphenone B, a new diarylheptanoid heterodimer from the seagrass Zostera marina, induces apoptosis cell death in colon cancer cells and reduces tumour growth in mice.

Colorectal cancer (CRC) is one of the most common malignant tumours worldwide. Diarylheptanoids, secondary metabolites isolated from Zostera marina, are of interest in natural products research due to their biological activities. Zosterabisphenone B (ZBP B) has recently been shown to inhibit the viability of CRC cells. The aim of this study was to investigate the therapeutic potential of ZBP B for targeting human CRC cells. Cell viability was determined using the MTT assay. Flow cytometry and Western blot analyses were used to assess apoptosis and autophagy. A CRC xenograft model was used to evaluate the in vivo effect of ZBP B. No cytotoxic effect on HCEC cells was observed in the in vitro experiments. ZBP B caused morphological changes in HCT116 colon cancer cells due to an increase in early and late apoptotic cell populations. Mechanistically, ZBP B led to an increase in cleaved caspase-3, caspase-8, caspase-9, PARP and BID proteins and a decrease in Bcl-2 and c-Myc proteins. In the xenograft model of CRC, ZBP B led to a reduction in tumour growth. These results indicate that ZBP B exerts a selective cytotoxic effect on CRC cells by affecting apoptotic signalling pathways and reducing tumour growth in mice. Taken together, our results suggest that ZBP B could be a lead compound for the synthesis and development of CRC drugs.

Abstract 6693: Deleted in malignant brain tumors 1 (DMBT1) glycoprotein is lost in colonic dysplasia

Abstract Colorectal cancer (CRC) is the third most common cancer in the United States and is responsible for more than 50,000 deaths annually. Emerging evidence strongly supports a causal role for specific pro-carcinogenic driver bacteria within the colonic microbiota. Invasive bacterial biofilms may initiate or accelerate CRC through epithelium-autonomous or inflammation-dependent mechanisms. To better understand host-microbe interactions during colonic tumorigenesis, we combined single-cell RNA-sequencing (scRNA-seq), spatial transcriptomics, and immunofluorescence to define the molecular spatial organization of colonic tissue from germ-free ApcMin/+ mice colonized with bacteria from human biofilm-associated CRC. In absorptive colonocytes, differential gene expression analysis showed the gastric metaplasia-associated glycoprotein Deleted in Malignant Brain Tumors 1 (DMBT1) is highly upregulated by C. difficile. Surprisingly, our spatial transcriptomic analysis showed DMBT1 was dramatically downregulated in dysplastic foci compared with normal-appearing tissue. We show that DMBT1 protein is downregulated in 100% of dysplastic foci across 3 different mouse models of colonic tumorigenesis: C. difficile-associated tumorigenesis in ApcMin/+, azoxymethane/dextran sodium sulfate, and Lrig1CreER/+;Apcfl/+ mice (n = 57 foci from 11 mice). Immunofluorescent staining of DMBT1 is markedly downregulated compared with normal adjacent crypts. Using scRNA-seq data and tissue microscopy in human CRC, we confirmed the same pattern of downregulated DMBT1 expression in dysplastic crypts compared with normal-appearing crypts. We present data from a human mucosal biofilm-associated colonic tumorigenesis murine model at single-cell resolution to reveal interesting cell type-specific transitions and generalizable mechanisms of tumorigenesis. We hypothesize that DMBT1 is a component of the gut epithelial response to pathogens and a critical regulator of proliferation and differentiation during post-injury restitution. We are now functionally testing how the loss of DMBT1 impacts tumorigenesis using human organoids. Ultimately, these studies aim to reveal novel biomarkers and/or targets for therapeutic intervention in CRC. Citation Format: Emily H. Green, Subhag R. Kotrannavar, Megan E. Rutherford, Harsimran Kaur, Hannah M. Lunnemann, Cody N. Heiser, Shaoguang Wu, Hua Ding, J. Alan Simmons, Xiao Liu, D. Borden Lacy, Martha J. Shrubsole, Qi Liu, Ken S. Lau, Cynthia L. Sears, Robert J. Coffey, Julia L. Drewes, Nicholas O. Markham. Deleted in malignant brain tumors 1 (DMBT1) glycoprotein is lost in colonic dysplasia [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 6693.

Abstract 6678: Microbial regulation of anti-tumor immunity in colorectal cancer

Abstract Colorectal cancer (CRC) is the 3rd leading site of cancers and cause of cancer cell death. Although Immunotherapies revolutionized cancer therapy, the majority of CRC patients, particularly with metastatic disease, do not respond to the treatments. This necessitates a better mechanistic understanding of the tumor-immune cell interactions in the context of CRC. Microbiome influences multiple biological aspects of the host including immune responses against cancers. Here, we show that the gut microbiome influences cancer MHC-I and -II expression levels and restricts tumor progression and metastasis, resulting in longer survival in 3 different CRC models and two different mouse strains. We found that the anti-tumor effects are dependent on T cells and B cells. Interestingly, depletion of B cell negated anti-metastatic effects of gut microbiome. Mechanistically, MHC-II expression in cancer cells mediates the anti-tumor effects of the microbiome. MHC-II upregulation on human CRC organoids enhances cancer-immune cell interactions and associated apoptosis, demonstrating an anti-tumor role and significance of MHC-II in human CRC. Thus, gut microbes that enhance MHC-II antigen presentation promotes anti-tumor immunity and may be utilized to enhance efficacy of immunotherapy in metastatic CRC. Citation Format: Charlie Chung, Elif Ozcelik, Jill Habel, Jialin Zhang, Yihan Qin, Libia Garcia, Joseph Merrill, Taemoon Chung, Scott Lyons, Zeli Shen, James G. Fox, Peter Westcott, Semir Beyaz. Microbial regulation of anti-tumor immunity 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 6678.

Abstract 1566: Cancer metastasis and stemness: The metastasis-inducer MACC1 regulates LGR5 to promote cancer stem cell-like properties in colorectal cancer

Abstract Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. The high mortality is directly associated with metastatic disease which is thought to be initiated by colon cancer stem cells according to cancer stem cell (CSC) model. Consequently, early identification of those patients who are at high risk for metastasis is crucial for improved treatment and patient outcome. Metastasis-associated in colon cancer 1 (MACC1) is a novel prognostic biomarker for tumor progression and metastasis formation independent of tumor stage. We previously showed an involvement of MACC1 in cancer stemness in the mouse intestine of our transgenic mouse models. However, the expression of MACC1 in human CSCs and possible implications remain elusive. Here, we explored the molecular mechanisms by which MACC1 regulates stemness and CSC-associated invasive phenotype based on patient-derived 3D cell culture models (PD3D), patient-derived xenografts (PDX) and human CRC cell lines. We showed that CD44-enriched CSCs from PD3D models express significantly higher levels of MACC1 and display higher tumorigenicity in immunocompromised mice. Similarly, RNA sequencing performed on PD3D and PDX models demonstrated significantly increased MACC1 expression in ALDH1(+) CSCs, highlighting its involvement in cancer stemness. We further showed the correlation of MACC1 with CSC markers CD44, NANOG and LGR5 in PD3D models as well as established cell lines. Additionally, MACC1 increased stem cell gene expression, clonogenicity and sphere formation. Strikingly, we showed that MACC1 binds as a transcription factor to the LGR5 gene promoter uncovering the long-known CSC marker LGR5 as novel essential signaling mediator used by MACC1 to induce CSC-like properties in human CRC patients. Our in vitro findings were further substantiated by significant positive correlation of MACC1 and LGR5 in CRC cell lines as well as CRC patient tumors. Taken together, this study indicates that the metastasis-inducer MACC1 act as a cancer stem cell-associated marker. Interventional approaches targeting MACC1 would potentially improve further targeted therapies for colorectal cancer patients to eradicate CSCs, prevent cancer recurrence and distant metastasis formation. Citation Format: Müge Erdem, Kyung Hwan Lee, Markus Hardt, Joseph Regan, Dennis Kobelt, Wolfgang Walther, Christian Regenbrecht, Ulrike S. Stein. Cancer metastasis and stemness: The metastasis-inducer MACC1 regulates LGR5 to promote cancer stem cell-like properties 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 1566.

Abstract 2167: Microbial bile acid, 3-oxo-LCA, inhibits colorectal cancer progression

Abstract Colorectal cancer (CRC) affects a significant number of individuals each year, ranking as a leading cause of cancer-related deaths in the U.S. Bile acids (BAs), natural compounds crucial for digesting dietary fats, not only influence the gut microbiota but are also involved in gut health through their interaction with the Farnesoid X Receptor (FXR). Recent findings have highlighted certain microbiota-generated BAs like 3-oxo-lithocholic acid (LCA) and IsoLCA, modulate host immunity, hinder the expansion of intestinal pathogens, and potentially anti-aging. Despite the advancements in identifying the gut microbes behind these BAs, their precise impact on intestinal cells (IECs) and their role in disease progression are largely unexplored. Our pilot investigation unveiled 3oxoLCA as an FXR agonist, restoring FXR signaling in both cancer cells and APCmin/+ mice (a classic CRC mice model). As a result, 3-oxo-LCA inhibits the growth of both human and mouse CRC cells, such as MC38, CT26 and HCT116. Additionally, 3-oxo-LCA also restrained the intestinal stem cells (ISCs)’ proliferation in organoids from both wild-type and APCmin/+ mice, and patient-derived CRC organoids (PDCOs). Remarkably, treatment with 3-oxo-LCA decreased BAs levels, improved gut barrier function, reduced tumor load, and inhibited tumor progression in APCmin/+ mice. Furthermore, 3-oxo-LCA significantly suppressed tumor growth in cancer cell-derived xenograft model mice. Crucially, the 3-oxo-LCA-FXR interaction transcriptionally regulated key apoptotic genes, encouraging cancer cell death. These discoveries highlight the therapeutic promise of incorporating 3-oxo-LCA into strategies for treating CRC. Citation Format: Fei Sun, Xingchen Dong, Ming Qi, Ting Fu. Microbial bile acid, 3-oxo-LCA, inhibits colorectal cancer progression [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 2167.

Abstract 2086: Effect of XPO1 inhibition on colorectal cancer tumorigenesis

Abstract Colorectal Cancer (CRC) is the second leading cause of cancer-related death in the U.S. A subset of individuals faces a notably higher likelihood of developing CRC within their lifetime. Hence, there is a compelling need for innovative chemopreventive treatments aimed at minimizing CRC tumorigenesis. Exportin 1 (XPO1; also referred to as CRM1) plays a pivotal role in transporting proteins from the nucleus to the cytoplasm. The overexpression of XPO1 has been identified across several cancers, including CRC. XPO1 interacts with a diverse spectrum of more than 1000 proteins. The overexpression of XPO1 leads to the excessive removal of tumor suppressors from the nucleus, rendering these proteins functionally inert. To counteract the overexpression of XPO1 in tumors, a novel class of drugs known as Selective Inhibitors of Nuclear Export (SINE) has been developed. Among these, Eltanexor (KPT-8602) has emerged as a promising therapeutic agent, demonstrating fewer side effects compared to its precursors, and is currently under evaluation in Phase 1/2 clinical trials. The treatment effects of SINE compounds on CRC remain largely unknown. We have assessed Eltanexor's ability to limit CRC tumorigenesis using a genetic CRC model in Apcmin/+ mice. Our findings indicate that Eltanexor substantially reduces tumor burden by approximately 3-fold and induces a significant reduction of tumors exceeding 1mm in size. Furthermore, a xenograft experiment using the human CRC cell line, HCT116, reveals nearly a 3-fold reduction in tumor size upon Eltanexor treatment. In both CRC models, Eltanexor exhibits noteworthy tolerability. Additionally, XPO1 protein levels are consistently diminished in both models, aligning with our in vitro observations. To further ascertain Eltanexor's specificity for CRC tumors versus normal tissue, we conducted drug sensitivity assays using organoids derived from Apcmin/+ tumors and wild-type mice small intestine tissue. We found that Apcmin/+ tumoroids have heightened sensitivity to Eltanexor-treatments, when compared to wild-type organoids. In an endeavor to elucidate Eltanexor's potent in vivo tumorigenesis inhibitory effects, we conducted multiple assays which revealed a reduction in COX-2 RNA and protein expression levels in Eltanexor-treated cells and reduced COX-2 protein in the tumors of Eltanexor-treated Apcmin/+ mice. In CRC, COX-2 is implicated in CRC development and is currently the target of multiple CRC chemopreventive agents. Our observations reveal that Eltanexor-treated CRC cells exhibit reduced COX-2 gene expression through both inhibiting COX-2’s promoter and its mRNA post-transcriptional stability. Collectively, our findings underscore XPO1 as a potent target for inhibiting CRC tumorigenesis. Future studies will aim to further assess how Eltanexor is impacting COX-2’s promoter, while additionally testing Eltanexor’s tumorigenesis-inhibiting potential in a colitis-induced CRC mouse model. Citation Format: Andrew E. Evans, Dan A. Dixon. Effect of XPO1 inhibition on colorectal cancer tumorigenesis [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 2086.

Abstract 1563: Anoikis associated metabolic modulation by UCA1 in CRC

Abstract Colorectal Cancer (CRC) is the second most lethal cancer in estimated deaths for 2023 according to the American Cancer Society. This is partially due to the low survival rate once CRC is diagnosed at a distant location. This warrants early diagnostic markers and an understanding of the mechanisms underlying the metastatic process, anoikis resistance being one of them. Our laboratory analysis of the TCGA database comprising 519 human CRC tissues shows lncRNA UCA1 overexpressed in tumors compared to normal, and higher expression of lncRNA UCA1 is responsible for the progression, metastasis, and poor survival of CRC patients. In our anchorage-independent growth model (anoikis resistant), using isogenic (oncogenic and metastatic) cell lines, we observed a very high expression of lncRNA UCA1 along with GluT1 with increased cell survival. Cancer cells, however, appear to rapidly increase their glucose uptake and directly ferment it into lactate, even in the presence of oxygen and functional mitochondria. UCA1 has been found to play an essential role in the development of metastasis and dysregulation of glycolysis in various cancers. To verify if lncRNA UCA1 modulates anoikis resistance and glucose metabolism, we generated SW480+UCA1 overexpression (OE) and SW620+shUCA1 knockdown (KD) stable cell lines using lentiviral transduction. The OE GFP-expressing cell lines were further sorted, and grown in puromycin. The KD cell lines were selected with puromycin for the generation of stable cell lines. The stable cell lines were characterized through different phenotypic assays. UCA1 OE cell lines have a higher glucose uptake and the UCA1 KD cell lines have a lower glucose uptake. The lactate production is high in the KD and low in OE cell lines. The OE and KD cell lines along with the control cell lines were subjected to an anoikis model, and glucose and lactate analysis were performed accordingly. RT-PCR and western blot analysis were performed for the target genes responsible for cell survival, stemness, and glucose metabolism. We are analyzing the Extracellular Acidification Rate (ECAR), Oxidative Consumption Rate (OCR), ATP production rate the rate and potential max rate of glycolysis, and the mitochondrial stress of the recombinant cell lines using the “Agilent Seahorse XF”. The role of lncRNA UCA1 in anoikis resistance leading to metastasis and modulating glucose metabolism will provide new insights into the pathophysiology of CRC metastasis. This information will be beneficial for developing more unique strategies for the treatment of this metastatic disease. Citation Format: Sophia Leslie, Kyle Doxtater, Samantha Lopez, Bilal Hafeez, Tamer Oraby, Timothy Loy, Manish K. Tripathi. Anoikis associated metabolic modulation by UCA1 in CRC [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 1563.

Abstract 4401: GATA6 is a novel regulator of gene expression and 3D genome in colorectal cancer

Abstract Colorectal cancer (CRC) is one of the most lethal and prevalent malignancies with elusive molecular causes. While the abnormal activity of transcription factors has been reported as a vital component of cancer progression, the mechanism through which they function remains unclear. Here, through the analysis of primary human CRC tissue data, we identified GATA6 as a CRC specific regulator, whose expression upregulation is potentially associated with promoter hypomethylation. In the human genome, GATA6 showed preferential binding at tumor specific active enhancers. Through both auxin-inducible degron (AID) and CRISPR knockout, we showed that GATA6 depletion severely impaired clonogenicity and proliferation. GATA6 depletion caused the loss of CRC specific open chromatin, suggesting a specific regulatory role of GATA6 in CRC pathogenesis. Interestingly, we also discovered the co-occupancy of GATA6 with CTCF and its direct involvement in promoter enhancer loops, suggesting the possibility that GATA6 mediate transcriptional regulation through 3D genome. The loss of GATA6 led to alterations in E-P chromatin interactions of a panel of oncogenes, accompanied by the oncogene downregulation. Finally, we showed that GATA6 loss is detrimental to the xenograft tumor growth and thereby rescued mice survival. Taken together, we unrevealed a novel mechanism by which GATA6 contributes to CRC. Citation Format: Huijue Lyu, Xintong Chen, Yang Cheng, Te Zhang, Ping Wang, Josiah Hiu-yuen Wong, Juan Wang, Lena Stasiak, Leyu Sun, Guangyu Yang, Lu Wang, Feng Yue. GATA6 is a novel regulator of gene expression and 3D genome 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 4401.

WTAP-induced N6-methyladenosine of PD-L1 blocked T-cell-mediated antitumor activity under hypoxia in colorectal cancer.

N6-Methyladenosine (m6A) is a important process regulating gene expression post-transcriptionally. Programmed death ligand 1 (PD-L1) is a major immune inhibitive checkpoint that facilitates immune evasion and is expressed in tumor cells. In this research we discovered that Wilms' tumor 1-associated protein (WTAP) degradation caused by ubiquitin-mediated cleavage in cancer cells (colorectal cancer, CRC) under hypoxia was inhibited by Pumilio homolog 1 (PUM1) directly bound to WTAP. WTAP enhanced PD-L1 expression in a way that was m6A-dependent. m6A "reader," Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) identified methylated PD-L1 transcripts and subsequently fixed its mRNA. Additionally, we found that T-cell proliferation and its cancer cell-killing effects were prevented by overexpression of WTAP invitro and invivo. Overexpression prevented T cells from proliferating and killing CRC by maintaining the expression of PD-L1. Further evidence supporting the WTAP-PD-L1 regulatory axis was found in human CRC and organoid tissues. Tumors with high WTAP levels appeared more responsive to anti-PD1 immunotherapy, when analyzing samples from patients undergoing treatment. Overall, our findings demonstrated a novel PD-L1 regulatory mechanism by WTAP-induced mRNA epigenetic regulation and the possible application of targeting WTAP as immunotherapy for tumor hypoxia.

Fusobacterium nucleatum promotes tumor progression in KRAS p.G12D-mutant colorectal cancer by binding to DHX15

Fusobacterium nucleatum (F. nucleatum) promotes intestinal tumor growth and its relative abundance varies greatly among patients with CRC, suggesting the presence of unknown, individual-specific effectors in F. nucleatum-dependent carcinogenesis. Here, we identify that F. nucleatum is enriched preferentially in KRAS p.G12D mutant CRC tumor tissues and contributes to colorectal tumorigenesis in Villin-Cre/KrasG12D+/- mice. Additionally, Parabacteroides distasonis (P. distasonis) competes with F. nucleatum in the G12D mouse model and human CRC tissues with the KRAS mutation. Orally gavaged P. distasonis in mice alleviates the F. nucleatum-dependent CRC progression. F. nucleatum invades intestinal epithelial cells and binds to DHX15, a protein of RNA helicase family expressed on CRC tumor cells, mechanistically involving ERK/STAT3 signaling. Knock out of Dhx15 in Villin-Cre/KrasG12D+/- mice attenuates the CRC phenotype. These findings reveal that the oncogenic effect of F. nucleatum depends on somatic genetics and gut microbial ecology and indicate that personalized modulation of the gut microbiota may provide a more targeted strategy for CRC treatment.

A54 SHP2 FUNCTION IN NORMAL AND APC-MUTANT INTESTINAL EPITHELIAL CELLS

Abstract Background Somatic SHP2 gain-of-function mutations were found in some colorectal tumours. However, its function in colorectal epithelium remains to be determined. SHP2 is a tyrosine phosphatase necessary for RAS/MAPK pathway activation by most, if not all, tyrosine kinase receptors, as well as by GPCRs and cytokine receptors. SHP2 can also regulate the PI3K, Jak/Stat, RhoA and Hippo pathways in different cell settings. As a result, SHP2 can control cellular processes including growth, migration and differentiation. Previously, we observed that SHP2 levels are enhanced in human colorectal tumours, notably in late adenomas. Likewise, SHP2 silencing inhibited ERK activation and tumour properties of established human CRC cell lines. Hence, these findings support a model in which SHP2 activation promotes tumorigenesis in the intestinal epithelium. But how? Aims To analyze the exact cellular and molecular mechanisms underlying SHP2 pro-oncogenic function in intestinal epithelial cells. Methods The impact of SHP2 pharmaco-inhibition (RMC-4550 and/or SHP099) on intracellular signaling, cell cycle, proliferation and survival was evaluated in three complementary models: 1) HIEC-6 cells, normal human fetal intestinal crypt-like cells; 2) organoids derived from normal mouse small intestine or ApcMin/+ tumors; 3) Caco-2/15 cells, colorectal cancer cells with APC mutation. Results 1- Pharmaco-inhibition of SHP2 blocks proliferation of HIEC-6 cells (loss of pRb phosphorylation, decreased EdU staining) and induces cell enlargement and darkening of the outside of perinuclear area. This phenotype was reminiscent of cellular senescence, and we indeed observed increased senescence-associated β-galactosidase activity (SA-β-Gal) and INK4A gene expression. 2- As expected, SHP2 inhibition in normal mouse organoids resulted in a reduction in the number of protrusions and EdU positive cells. RNA sequencing was performed, and gene set enriched revealed significant down regulation of several Ras signaling-dependant genes including cell cycle regulated genes (E2F targets, G2/M checkpoint) and Myc targets 48h after SHP2 inhibition when compared to DMSO treated organoids. Genes associated with PI3K signaling were also diminished in SHP099 treated organoids but no significant modulation of genes associated with Wnt/b-catenin signaling was observed. 3- Notably, SHP2 pharmaco-inhibition in Caco-2/15 cells as well as APC-mutant organoids rapidly induced cell death associated with increased expression of stem cell markers. Conclusions These results suggest that SHP2 is required for proliferation of normal IEC and protects against senescence. Notably, its inhibition restrains the proliferative and tumorigenic potential conferred by APC inactivation. Overall, our data suggest that SHP2 could represent a potential target to counter colorectal tumour initiation. Funding Agencies CIHRFRQS

OLFM2 promotes epithelial-mesenchymal transition, migration, and invasion in colorectal cancer through the TGF-β/Smad signaling pathway

BackgroundColorectal cancer (CRC) is an aggressive tumor of the gastrointestinal tract, which is a major public health concern worldwide. Despite numerous studies, the precise mechanism of metastasis behind its progression remains elusive. As a member of the containing olfactomedin domains protein family, olfactomedin 2 (OLFM2) may play a role in tumor metastasis. It is highly expressed in colorectal cancer, and its role in the metastasis of CRC is still unclear. As such, this study seeks to explore the function of OLFM2 on CRC metastasis and its potential mechanisms.MethodsReal-time fluorescence quantitative PCR and western blotting were used to study the expression of OLFM2 in human CRC and adjacent normal tissues. Knockdown and overexpression OLFM2 cell lines were constructed using siRNA and overexpression plasmids to explore the role of OLFM2 in the migration and invasion of CRC through transwell, and wound healing experiments. Finally, the expression of epithelial-mesenchymal transition (EMT) -related proteins and TGF-β/Smad signaling pathway-related proteins was investigated using western blotting.ResultsIn this study, we observed an elevation of OLFM2 expression levels in CRC tissues. To investigate the function of OLFM2, we overexpressed and knocked down OLFM2. We discovered that OLFM2 knockdown inhibited migration and invasion of colon cancer cells. Furthermore, E-cadherin expression increased while N-cadherin and Vimentin expression were opposite. It is no surprise that overexpressing OLFM2 had the opposite effects. We also identified that OLFM2 knockdown resulted in reduced TGF-βR1 and downstream molecules p-Smad2 and p-Smad3, which are related to the TGF-β / Smad pathway. In contrast, overexpressing OLFM2 significantly boosted their expression levels.ConclusionThe protein OLFM2 has been identified as a crucial determinant in the progression of CRC. Its mechanism of action involves the facilitation of EMT through the TGF-β/Smad signaling pathway. Given its pivotal role in CRC, OLFM2 has emerged as a promising diagnostic and therapeutic target for the disease. These results indicate the potential of OLFM2 as a valuable biomarker for CRC diagnosis and treatment and highlight the need for further research exploring its clinical significance.

Synergistic anti-tumor activity, reduced pERK, and immuno-stimulatory cytokine profiles with 5-FU or ONC212 plus KRAS G12D inhibitor MRTX1133 in CRC and pancreatic cancer cells independent of G12D mutation.

KRAS mutations occur in ~40-50% of mCRC and are associated with aggressive disease that is refractory to anti-EGFR therapies. Pancreatic cancer harbors ~90% KRAS driver gene mutation frequency. Small molecules targeting KRAS G12C gained FDA approval for KRAS G12C-mutated NSCLC. ONC212, a fluorinated imipridone with nM anti-cancer activity has preclinical efficacy against pancreatic cancer and other malignancies. MRTX1133, identified as a noncovalent selective KRAS G12D inhibitor that suppresses G12D signaling by binding to the switch II pocket thereby inhibiting protein-protein interactions. We investigated cell viability, drug synergies, pERK suppression and cytokine, chemokine or growth factor alterations following treatment with 5-Fluorouracil (5-FU) or ONC212 plus MRTX1133 in 6 human CRC and 4 human pancreatic cancer cell lines. IC50 sensitivities ranged from 7 to 12 µM for 5-FU, 0.2-0.8 µM for ONC212, and > 100 nM to > 5,000 nM for MRTX1133 (G12D N = 4: LS513 > 100, HPAF-II > 1,000, SNUC2B > 5,000, PANC-1 > 5,000). For non-G12D, the range of IC50 for MRTX1133 was > 1,000 to > 5,000 nM for CRC lines with G12V, G13D, or WT KRAS (N = 7). Synergies between MRTX1133 plus 5-FU or ONC212 were observed regardless of KRAS G12D mutation with combination indices of < 0.5 indicating strong synergy. Observed synergies were greater with MRTX1133 plus ONC212 compared to MRTX1133 plus 5-FU. pERK was suppressed with mutant but not wild-type KRAS at nM MRTX1133 doses. Immunostimulatory profiles included reduction in IL8/CXCL8, MICA, Angiopoietin 2, VEGF and TNF-alpha and increase in IL-18/IL-1F4 with MRTX treatments and combinations. Our studies reveal preclinical activity of MRTX1133 alone or synergies when combined with 5-FU or ONC212 against mCRC and pancreatic cancer cells regardless of KRAS G12D mutation. The results suggest that KRAS G12V and KRAS G13D should be further considered in clinical trials including combination therapies involving MRTX1133 and 5-FU or ONC212.

Homologous proteins SAPCD2X1 and SAPCD2 have significantly different carcinogenic capacities in human colorectal cancer cells based on structural prediction and functional verification.

We discussed the expression and biological functions of the SAPCD2X1 protein in the HCT116 CRC cell line by bioinformatics analysis and prediction, and biological function verification. Spatial conformation models of SAPCD2X1 and SAPCD2 were predicted using the threading method, ensemble method, and several other protein structure prediction approaches. The conformational similarity between SAPCD2X1 and SAPCD2 was studied, and their functions were predicted. The biological experiments showed that SAPCD2X1 and SAPCD2 were overexpressed in CRC cells. SAPCD2X1-specific antibodies were prepared. The expressions of SAPCD2X1 and SAPCD2 were localized in cells using the immunofluorescence assay. The SAPCD2 and SAPCD2X1 overexpression models were validated using Western Blot and RT-qPCR. We successfully predicted the structures of the SAPCD2X1 and SAPCD2 proteins, and visualized them using the VDM software. It was predicted that the tertiary structure of SAPCD2X1 changed significantly compared with SAPCD2. Alteration of the biological functions of SAPCD2X1 was also predicted due to the changes in the spatial conformation of the protein. Anti-SAPCD2X1 antibody and SAPCD2X1-EGFP and SAPCD2-EGFP recombinant plasmids were established. The overexpression of the two proteins was induced in HCT116 cells using the recombinant plasmids, and verified by RT-qPCR and Western Blot. Meanwhile, the anti-SAPCD2X1 antibody was proved to have a high specificity. The immunofluorescence assay showed that SAPCD2X1 and SAPCD2 are mainly expressed in the cytoplasm. SAPCD2X1 and SAPCD2 exhibited significantly different biological functions in HCT116 cells. SAPCD2 is a carcinogenic protein, while SAPCD2X1 does not affect the proliferation, invasion, and migration of human CRC HCT116 cells.

MHY446 induces apoptosis via reactive oxygen species-mediated endoplasmic reticulum stress in HCT116 human colorectal cancer cells

This study investigated the potential of a newly synthesized histone deacetylase (HDAC) inhibitor, MHY446, in inducing cell death in HCT116 colorectal cancer cells and compared its activity with that of suberoylanilide hydroxamic acid (SAHA), a well-known HDAC inhibitor. The results showed that MHY446 increased the acetylation of histones H3 and H4 and decreased the expression and activity of HDAC proteins in HCT116 cells. Additionally, MHY446 was confirmed to bind more strongly to HDAC1 than HDAC2 and inhibit its activity. In vivo experiments using nude mice revealed that MHY446 was as effective as SAHA in inhibiting HCT116 cell-grafted tumor growth. This study also evaluated the biological effects of MHY446 on cell survival and death pathways. The reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) confirmed that ROS play a role in MHY446-induced cell death by reducing poly(ADP-ribose) polymerase cleavage. MHY446 also induced cell death via endoplasmic reticulum (ER) stress by increasing the expression of ER stress-related proteins. NAC treatment decreased the expression of ER stress-related proteins, indicating that ROS mediate ER stress as an upstream signaling pathway and induce cell death. While MHY446 did not exhibit superior HDAC inhibition efficacy compared to SAHA, it is anticipated to provide innovative insights into the future development of therapeutic agents for human CRC by offering novel chemical structure-activity relationship-related information.