Tumor Microenvironment Research Articles

CK2B is a Prognostic Biomarker and a Potential Drug Target for Hepatocellular Carcinoma.

Although casein kinase II subunit beta (CK2B) was previously reported to be involved in human cancers, such as hepatocellular carcinoma (HCC), there has been no systematic assessment of CK2B in HCC. To assess the potential function of CK2B as a prognostic biomarker and possible druggable target in HCC. The Cancer Genome Atlas database was accessed to investigate the potential oncogenic and prognostic roles of CK2B in HCC. Diverse analytical methods were used to obtain a fuller understanding of CK2B, including CIBERSORT, The Tumor Immune Estimation Resource (TIMER), gene set enrichment analyses (GSEA), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene ontology (GO). Furthermore, the Comparative Toxicogenomic Database (CTD) was used to identify potential drugs to treat CK2B-overexpressing HCC. Patents for these drugs were reviewed using Patentscope® and Worldwide Espacenet®. Upregulated CK2B expression was markedly associated with more aggressive pathological features, including G3, G4 (vs. G1, G2), and T2, T3 (vs. T1). Kaplan-Meier survival curves indicated that patients with HCC with higher expression of CK2B had worse overall survival (P = 0.005), progression-free interval (P = 0.001), and disease-specific survival (P = 0.011). GO and KEGG analysis revealed that CK2B dysregulation affects mitotic chromosome condensation, protein stabilization and binding, regulation of signal transduction of p53 class mediator, and cancer-related pathways. GSEA identified six well-known pathways, including MAPK, WNT, Hedgehog, and TGFβ signaling pathways. Finally, CTD identified six compounds that might represent targeted drugs to treat HCC with CK2B overexpression. A review of patents indicated these compounds showed promising anticancer results; however, whether CK2B interacts with these drugs and improves drug outcomes for patients with HCC was not confirmed. CK2B is a biomarker for HCC prognosis and could be a potential new drug target. Moreover, the association between infiltrating immune cells and CK2B in the HCC tumor microenvironment might provide a solid basis for further investigation and a potent strategy for immunotherapy of HCC.

Prediction of clinical prognosis and drug sensitivity in hepatocellular carcinoma through the combination of multiple cell death pathways.

Hepatocellular carcinoma (HCC) is the sixth most common malignant tumor, highlighting a significant need for reliable predictive models to assess clinical prognosis, disease progression, and drug sensitivity. Recent studies have highlighted the critical role of various programmed cell death pathways, including apoptosis, necroptosis, pyroptosis, ferroptosis, cuproptosis, entotic cell death, NETotic cell death, parthanatos, lysosome-dependent cell death, autophagy-dependent cell death, alkaliptosis, oxeiptosis, and disulfidptosis, in tumor development. Therefore, by investigating these pathways, we aimed to develop a predictive model for HCC prognosis and drug sensitivity. We analyzed transcriptome, single-cell transcriptome, genomic, and clinical information using data from the TCGA-LIHC, GSE14520, GSE45436, and GSE166635 datasets. Machine learning algorithms were used to establish a cell death index (CDI) with seven gene signatures, which was validated across three independent datasets, showing that high CDI correlates with poorer prognosis. Unsupervised clustering revealed three molecular subtypes of HCC with distinct biological processes. Furthermore, a nomogram integrating CDI and clinical information demonstrated good predictive performance. CDI was associated with immune checkpoint genes and tumor microenvironment components using single-cell transcriptome analysis. Drug sensitivity analysis indicated that patients with high CDI may be resistant to oxaliplatin and cisplatin but sensitive to axitinib and sorafenib. In summary, our model offers a precise prediction of clinical outcomes and drug sensitivity for patients with HCC, providing valuable insights for personalized treatment strategies.

Enhanced antitumor activity of lapatinib against triple-negative breast cancer via loading in human serum albumin

Triple-negative breast cancer (TNBC) presents significant treatment challenges due to its aggressive nature. Human serum albumin (HSA) is a promising drug delivery platform, offering high binding capacity, biocompatibility, and reduced toxicity. Lapatinib (LAP), a tyrosine kinase inhibitor for TNBC, is hindered by poor water solubility and toxicity. To address these issues, LAP was encapsulated within HSA (HSA-LAP), and its structural, drug release, and therapeutic properties were evaluated in cellular and animal TNBC models. HSA-LAP demonstrated efficient drug loading and pH-dependent tumor-targeted release, favoring acidic tumor microenvironments. Structural and microscopic studies confirmed LAP binding to HSA, with only minor structural and no significant morphological changes observed. In 4 T1 breast cancer cells, HSA-LAP exhibited superior anti-proliferative, pro-apoptotic, and anti-migratory effects compared to free LAP, which were further amplified when combined with VGB3, a VEGFR1/2-targeting peptide, indicating an effective dual-targeting strategy for TNBC. In vivo, HSA-LAP showed greater tumor inhibition and improved survival rates, especially in combination with VGB3 through apoptosis induction. Biodistribution studies using technetium-99 m (99mTc) labeling revealed enhanced tumor targeting. These findings highlight the potential of HSA as a delivery vehicle for LAP, particularly in combination with anti-angiogenic agents like VGB3, offering a promising therapeutic strategy for TNBC.

Extracellular vesicles powered cancer immunotherapy: Targeted delivery of adenovirus-based cancer vaccine in humanized melanoma model.

Malignant melanoma, a rapidly spreading form of skin cancer, is becoming more prevalent worldwide. While surgery is successful in treating early-stage melanoma, patients with advanced disease have only a 20% chance of surviving beyond five years. Melanomas with mutations in the NRAS gene are characterized for a more aggressive tumor biology, poorer prognosis and shorter survival. Hence, new therapeutic strategies are needed, especially for this specific group of patients. Novel approaches, such as cancer vaccines, offer promising solutions by stimulating the anti-tumor immune response. Nevertheless, their clinical efficacy is still modest and more effective approaches are required. Herein, we propose the systemic administration of the adenovirus-based cancer vaccine complexed in extracellular vesicles (EVs) with the aim of achieving a targeted therapeutic effect. The vaccine was based on previously tested oncolytic adenovirus Ad5/3-D24-ICOSL-CD40L in combination with melanoma-specific antigens targeting NRAS mutations to enhance the anticancer effect. The antineoplastic properties of the oncolytic vaccine were evaluated in xenograft MUG Mel-2 melanoma BALB/c nude mice. Moreover, to mimic the tumor microenvironment, while investigating at the same time immune cell infiltration and drug penetration, we established a 3D co-culture model based on human NRAS mutated MUG Mel-2 spheroids and PBMCs (HLA matched), which displayed a synergistic effect when treated with the cancer vaccine compared to relative controls. Subsequently, we investigated the systemic delivery of the vaccine in EV formulations in a humanized NSG MUG Mel-2 melanoma mouse model. Our study provides a promising strategy for a tumor-targeted vaccine delivery by EVs, resulting in improved anticancer efficacy and increased infiltration of tumor-infiltrating lymphocytes. This study explores the potential of EVs for the selective delivery of cancer vaccines against malignancies, such as NRAS melanoma. Overall, this research could pave the way for applying autologous EVs as a safe and efficacious tool for targeted cancer therapy.

Immunological impact of intraperitoneal and intravenous chemotherapy in ovarian cancer, translational analyses of the Phase 3 iPocc trial

BackgroundThe iPocc trial, a randomized, global phase 3 study that compared intraperitoneal (IP) and intravenous (IV) carboplatin with dose-dense paclitaxel chemotherapy in epithelial ovarian cancer (EOC) patients, demonstrated improved progression-free survival in patients who received IP chemotherapy. The present study aimed to investigate the role of preexisting tumor immunity in the clinical outcomes of patients receiving IP chemotherapy. MethodsThis study involved analyzing patient data from the iPocc trial, selectively of those whose tumor specimens were preserved at the time of primary surgery. A total of 116 cases ((IP; n = 59), (IV; n = 57)) were subjected to microarray analysis. Single-sample gene set enrichment analyses were performed to evaluate the tumor immune microenvironment. ResultsPatients with enhanced tumor infiltration of T cells, natural killer (NK) cells, and cytotoxic lymphocytes in the IP group had a longer overall survival (OS) than those in the IV group, but not in the group with low infiltration. IP therapy improved the OS of patients with high expression of immune-related genes such as CD8A and FOXP3. In patients' subdivided into “immune Hot” and “immune Cold” groups based on hierarchical clustering analysis using four parameters representing “Innate immunity,” “T cells,” “IFNG response” and “Inhibitory molecules,” IP therapy significantly improved prognosis in the “immune Hot” group, but not in the “immune Cold” group compared to that of IV therapy. ConclusionsIP chemotherapy enhances the survival rates of patients with EOC with an immune-Hot phenotype in the tumor microenvironment prior to treatment.(Japan Registry of Clinical Trials number, jRCTs031180141.)

The oncomicrobiome: New insights into microorganisms in cancer.

The discoveries of the oncomicrobiome (intratumoral microbiome) and oncomicrobiota (intratumoral microbiota) represent significant advances in tumor research and have rapidly become of key interest to the field. Within tumors, microorganisms such as bacteria, fungi, viruses, and archaea form the oncomicrobiota and are primarily found within tumor cells, immunocytes, and the intercellular matrix. The oncomicrobiome exhibits marked heterogeneity and is associated with tumor initiation, progression, metastasis, and treatment response. Interactions between the oncomicrobiome and the immune system can modulate host antitumor immunity, influencing the efficacy of immunotherapies. Oncomicrobiome research also faces numerous challenges, including overcoming methodological issues such as low target abundance, susceptibility to contamination, and biases in sample handling and analysis methods across different studies. Furthermore, studies of the oncomicrobiome may be confounded by baseline differences in microbiomes among populations driven by both environmental and genetic factors. Most studies to date have revealed associations between the oncomicrobiome and tumors, but very few have established mechanistic links between the two. This review introduces the relevant concepts, detection methods, sources, and characteristics of the oncomicrobiome. We then describe the composition of the oncomicrobiome in common tumors and its role in shaping the tumor microenvironment. We also discuss the current problems and challenges to be overcome in this rapidly progressing field.

Self-delivered sonodynamic nanomedicine for enhanced tumor immunotherapy by simultaneously reversing the immunosuppression and immune resistance

Sonodynamic therapy (SDT) shows potential for noninvasive eradication of local solid tumors. However, its efficacy in suppressing metastatic tumors is limited by factors such as insufficient tumor accumulation, the immunosuppressive tumor microenvironment, and acquired immune tolerance. To address these challenges, we developed self-delivering sonodynamic nanomedicine incorporating Toll-like receptor (TLR) agonists R848 and programmed death-ligand 1 (PD-L1) inhibitors JQ1 for combined SDT and immunotherapy. These nanomedicines enhanced tumor accumulation of sonosensitizers, enabling potent SDT and induction of immunogenic cell death (ICD). Additionally, the co-encapsulated R848 and JQ1 alleviated tumor immunosuppression and immune tolerance, synergizing effectively with SDT to elicit a robust antitumor immune response. By integrating enhanced SDT with activated antitumor immunity, significant inhibition of primary, distant, and lung metastatic tumors was achieved. This study introduces a novel approach for combining SDT with immunotherapy using self-assembled active pharmaceutical ingredients.

Hypoxia-related bioinformatic signatures associated with prognosis and tumor microenvironment of pancreatic cancer: Current status, concerns, and future perspectives

Pancreatic cancer (PC), a highly lethal tumor with nearly identical incidence and mortality rates, has become the sixth leading cause of cancer-related deaths. Hypoxia is an important malignant factor in PC, as it regulates angiogenesis, metabolic reprogramming, tumor progression, and metastasis. Disrupting the hypoxic microenvironment can enhance the efficacy of antitumor therapy and improve the prognosis of patients with PC. With the advent of bioinformatics, hypoxia-related PC models have emerged in recent years. They provide a reference for estimating the prognosis and immune microenvironment of patients with PC and identify potential biomarkers for targeting hypoxic microenvironment. However, these findings based on bioinformatic analysis may not be completely reliable without further experimental evidence and clinical cohort validation. The application of these models and biomarkers in clinical practice to predict survival time and develop anti hypoxic therapeutic strategies for patients with PC remains in its infancy. In this editorial, we review the current status of hypoxia-related prognostic models in PC, analyze their similarities and differences, discuss several existing challenges, and provide potential solutions and directions for further studies. This editorial will facilitate the optimization, validation, and determination of the molecular mechanisms of related models.

Potential regulatory mechanism and clinical significance of synaptotagmin binding cytoplasmic RNA interacting protein in colorectal cancer

BACKGROUND Colorectal cancer (CRC) causes many deaths worldwide. Synaptotagmin binding cytoplasmic RNA interacting protein (SYNCRIP) is an RNA-binding protein that plays an important role in multiple cancers by epigenetically targeting some genes. Our study will examine the expression, potential effect, biological function and clinical value of SYNCRIP in CRC. AIM To examine the expression, potential effect, biological function and clinical value of SYNCRIP in CRC. METHODS The expression of SYNCRIP was examined by immunohistochemistry arrays and high-throughput data. The effect of SYNCRIP gene in CRC cell growth was evaluated by CRISPR-Cas9 technology. The target genes of SYNCRIP were calculated using various algorithms, and the molecular mechanism of SYNCRIP in CRC was explored by mutation analysis and pathway analysis. The clinical value of SYNCRIP in prognosis and radiotherapy was revealed via evidence-based medicine methods. RESULTS The protein and mRNA levels of SYNCRIP were both highly expressed in CRC samples compared to nontumorous tissue based on 330 immunohistochemistry arrays and 3640 CRC samples. Cells grew more slowly in eleven CRC cell lines after knocking out the SYNCRIP gene. SYNCRIP could epigenetically target genes to promote the occurrence and development of CRC by boosting the cell cycle and affecting the tumor microenvironment. In addition, CRC patients with high SYNCRIP expression are more sensitive to radiotherapy. CONCLUSION SYNCRIP is upregulated in CRC, and highly expressed SYNCRIP can accelerate CRC cell division by exerting its epigenetic regulatory effects. In addition, SYNCRIP is expected to become a potential biomarker to predict the effect of radiotherapy.

New insights into the role of the CHI3L2 protein in invasive ductal breast carcinoma

AbstractChitinase-like proteins have multiple biological functions that promote tumor growth, angiogenesis and metastasis. Expression of CHI3L2, which is similar in structure to CHI3L1, is detected in glioma cells and tumor-associated macrophages (TAMs) in glioma and breast cancer. However, its exact role remains unclear. We analyzed the expression of CHI3L2 in 74 invasive ductal breast carcinoma (IDC) tumors, breast cancer and macrophages cell cultures using immunohistochemistry, immunofluorescence, Western blot and PCR methods. Clinicopathologic data were included in the analysis. The results obtained show that CHI3L2 expression decreases with increasing degree of tumor grade and negative status of estrogen (ER) and progesterone receptors (PR). Furthermore, CHI3L2 is significantly and positively correlated with phosphorylation of STAT-3 and ERK1/2 signaling pathways, but negatively correlated with macrophage infiltration. CHI3L2 is expressed both in the cytoplasm of cancer cells and in macrophages and may regulate STAT-3 and ERK1/2 phosphorylation in breast cancer cell lines. Analysis of the clinicopathologic data revealed that CHI3L2 levels had no effect on patient survival. CHI3L2 expression may be specific for cancer cells in IDC and involved in cross-talk with the tumor microenvironment. Our study has shown that IDC cancer cells express the CHI3L2 protein, possibly indicating a novel function of this protein.

Cutaneous T cell lymphoma atlas reveals malignant TH2 cells supported by a B cell-rich tumor microenvironment

AbstractCutaneous T cell lymphoma (CTCL) is a potentially fatal clonal malignancy of T cells primarily affecting the skin. The most common form of CTCL, mycosis fungoides, can be difficult to diagnose, resulting in treatment delay. We performed single-cell and spatial transcriptomics analysis of skin from patients with mycosis fungoides-type CTCL and an integrated comparative analysis with human skin cell atlas datasets from healthy and inflamed skin. We revealed the co-optation of T helper 2 (TH2) cell-immune gene programs by malignant CTCL cells and modeling of the tumor microenvironment to support their survival. We identified MHC-II+ fibroblasts and dendritic cells that can maintain TH2 cell-like tumor cells. CTCL tumor cells are spatially associated with B cells, forming tertiary lymphoid structure-like aggregates. Finally, we validated the enrichment of B cells in CTCL and its association with disease progression across three independent patient cohorts. Our findings provide diagnostic aids, potential biomarkers for disease staging and therapeutic strategies for CTCL.

Tumor microenvironment remodeling after neoadjuvant chemoradiotherapy in local advanced rectal cancer revealed by single-cell RNA sequencing

Tumor microenvironment remodeling after neoadjuvant chemoradiotherapy in local advanced rectal cancer revealed by single-cell RNA sequencing

IL-2/anti-IL-2 antibody complexes augment immune responses to therapeutic cancer vaccines

One driver of the high failure rates of clinical trials for therapeutic cancer vaccines is likely the inability to sufficiently engage conventional dendritic cells (cDCs), the antigen-presenting cell (APC) subset that is specialized in priming antitumor T cells. Here, we demonstrate that, relative to vaccination with an injectable mesoporous silica rod (MPS) vaccine alone (Vax), combining MPS vaccines with CD122-biased IL-2/anti-IL-2 antibody complexes (IL-2cx) drives ~3-fold expansion of cDCs at the vaccination sites, vaccine-draining lymph nodes, and spleens of treated mice. Furthermore, relative to Vax alone, Vax+IL-2cx led to a ~3-fold increase in the numbers of CD8 + T cells and ~15-fold increase in the numbers of NK cells at the vaccination site. Notably, with both the model protein antigen OVA as well as various peptide neoantigens, Vax+IL-2cx induced ~5 to 30-fold greater numbers of circulating antigen-specific CD8 + T cells relative to Vax alone. We further demonstrate that Vax+IL-2cx leads to significantly improved efficacy in the MC38 colon carcinoma model relative to either monotherapy alone, driving complete regressions in 50% of mice in a cDC-dependent manner. Relative to vaccine alone, Vax+IL-2cx led to comparable numbers of CD8 + T cells, but markedly greater numbers of NK cells and activated cDCs in the B16F10 melanoma tumor microenvironment post-therapy. Taken together, these findings suggest that the administration of factors that engage both the cDC-CD8 + T cell and cDC-NK cell axes can boost the potency of therapeutic cancer vaccines.

Abstract B015: Targeting CX3CL1 transforms a cold tumor microenvironment into a hot one by enhancing T cells and DCs locally and systemically

Abstract Intratumoral heterogeneity (ITH) is associated with immunotherapy failure and a weaker anti- tumor immune response. Using a series of carcinogen-induced tumor (CIT) squamous cell skin carcinoma cell lines, our lab has sought to identify tumor-intrinsic factors—particularly chemokines and cytokines—which can have a “dominant negative” effect on the immune microenvironment when present within a heterogeneous tumor. We identified CX3CL1 as a one such critical mediator of a cold (T cell low) immune microenvironment and found that tumors containing as few as 10% CX3CL1high tumor cells exhibit a diminished T cell response compared to tumors which lack CX3CL1high tumor cells. We predicted that targeting CX3CL1 could therefore transform a cold tumor microenvironment (TME) into an inflammatory hot (T cell high) TME. Supporting this, we found that CRISPR-Cas9-mediated deletion of CX3CL1 in a tumor cell line that typically gives rise to cold tumors led to higher T cell infiltration and fewer immunosuppressive macrophages in the TME of CX3CL1-/- tumors. Building on this, we further explored T cell populations in the TME and found that CX3CL1-/- tumors had significantly increased activation and decreased exhaustion markers on T cells. Flow cytometry analysis showed higher expression of CD44 on effector CD4 T cells and an increase in the number of activated CD44+ PD1low CD4 T cells. By contrast, the frequency of CD4 T cells which were PD1High TIM3+ and PD1High TIM3+ TIGIT+ which represent a likely exhausted effector CD4 population was lower in CX3CL1-/- tumors than in counterpart control tumors. An interrogation of DC subsets in the TME further revealed a higher number of cDC1 and cDC2 populations in CX3CL1−/− tumors. To determine the effect of tumor-produced CX3CL1 on immune activity in lymphoid organs, we investigated T cell and DC markers in the spleen and tumor-draining lymph nodes during early tumor development. Spleens harvested 10 days after tumor injection showed higher infiltration of cDC1 CCR7+ and cDC2 CCR7+ mature DCs in CX3CL1-/- tumor-bearing mice. Thus, in the absence of tumor-produced CX3CL1, both cDC1 and cDC2 dendritic cell subsets attain more mature phenotypes in both the TME and the spleen. At the same time point, tumor-draining lymph nodes also exhibited a shift in immune cell composition characterized by an increased frequency of T cells, particularly CD4+ T cells, and a decreased frequency of B cells. Moreover, the percentage of PD1+ CD8 cells was also higher, indicating better priming and activation of CD8 T cells via DCs in tumor-draining lymph nodes. These findings indicate that tumor-produced CX3CL1 drives a cold immune microenvironment through both tumor-localized and systemic effects. These studies suggest therapeutically targeting CX3CL1 particularly in tumors where tumor cells produce high levels of CX3CL1 holds promise to transform a cold TME into a hot immune inflammatory TME and potentiate better anti-tumor immunity. Citation Format: Piyush Chaudhary, Savannah Hughes, Joshua Tay, Robert Letchworth, Miho Tanaka, Melissa Reeves. Targeting CX3CL1 transforms a cold tumor microenvironment into a hot one by enhancing T cells and DCs locally and systemically [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B015.

Abstract A017: HER2 overexpression initiates breast tumorigenesis non-cell-autonomously by altering energy metabolism in the tissue microenvironment

Abstract Breast cancer is the most common cancer globally, with approximately 70% of pre-malignant breast tumors, known as ductal carcinoma in situ (DCIS), and 20% of invasive breast tumors overexpressing human epidermal growth factor receptor 2 (HER2). While the biological role of HER2 in invasive breast cancer has been extensively studied, its impact on breast cancer stem cells (BCSCs) and early-stage tumorigenesis, particularly within the tumor microenvironment, remains unclear. Here, we explore the role of HER2 overexpression in driving cellular events within the tumor microenvironment during the premalignant stage of breast tumorigenesis, using in vitro, in vivo, and ex vivo models. We conducted multi-omics analyses on mammary ducts from a HER2+ breast cancer mouse model at the pre-cancerous stage. Our results showed that HER2/Neu overexpression alters glucose and lipid metabolism and pentose phosphate pathway in mammary epithelial cells. Ex vivo organ culture of mammary ducts confirmed that these metabolic changes lead to increased reactive oxygen species (ROS) levels within the tumor microenvironment suggesting that oxidative stress and subsequent DNA damage are early events in HER2-driven tumorigenesis. Immunostaining of histological sections from mouse mammary glands further revealed that elevated oxidative stress and DNA damage not only in HER2+ cells but also in neighboring HER2- cells. Moreover, whole genome sequencing of tumor cells confirmed that both HER2+ and HER2- tumor cells have similar mutational burden. This suggests a non-cell-autonomous effect, where HER2 overexpression in one cell population affects the tumor microenvironment and adjacent cells, contributing to early-stage cancer development. To investigate the involvement of BCSCs during tumor initiation, we performed mammosphere assays on primary cells from HER2+ mouse models and clinical DCIS samples. Our findings showed that neither BCSCs nor their cells of origin express HER2 in both DCIS samples and murine mammary glands and tumors. This suggests that HER2 overexpression may not directly drive BCSC formation but rather creates a genotoxic microenvironment that facilitates the transformation of HER2- cell populations through a non-cell-autonomous mechanism. In summary, our findings indicate that HER2 overexpression contributes to the creation of a genotoxic tumor microenvironment by altering cellular energy metabolism and increasing ROS levels. This, in turn, may lead to the transformation of BCSCs in HER2- cell populations during early breast tumorigenesis. Understanding the role of HER2 overexpression in shaping the tumor microenvironment could provide new insights into therapeutic and preventive strategies against breast cancer. Citation Format: Sevim B. Gurler, Oliver Wagstaff, Lili Dimitrova, Fuhui Chen, Robert Pedley, William Weston, Ian J. Donaldson, Brian A. Telfer, David Novo, Kyriaki Pavlou, George Taylor, Yaqing Ou, Kaye Williams, Andrew Gilmore, Keith Brennan, Ahmet Ucar. HER2 overexpression initiates breast tumorigenesis non-cell-autonomously by altering energy metabolism in the tissue microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A017.

Abstract B028: The Role of cDC1 Gene Signatures in gastric cancer prognosis and immune microenvironment modulation

Abstract Background and Aim: Gastric cancer (GC) continues to be a major global health burden, with a growing body of evidence highlighting the critical role of conventional type 1 dendritic cells (cDC1s) within the tumor microenvironment. This study aims to elucidate the prognostic significance of cDC1-associated genes—CD141, XCR1, CLEC9A, CADM1, and BTLA—in gastric cancer, as well as to explore the biological mechanisms that underpin their effects on patient outcomes. Materials and Methods: We conducted a comprehensive analysis of RNA- seq data from The Cancer Genome Atlas (TCGA-STAD) and Gene Expression Omnibus (GEO) datasets, focusing on the expression profiles of five cDC1-related genes. Patients were stratified into high and low expression groups based on a defined cDC1 gene signature. To assess the impact of these signatures, we utilized gene set variation analysis (GSVA) to examine relevant oncogenic pathways and performed Kaplan-Meier survival analysis along with Cox proportional hazards modeling to evaluate their prognostic value. Results: Our findings demonstrate that patients exhibiting a high cDC1-related gene signature had significantly worse overall and disease-free survival within the TCGA-STAD cohort. Further analysis revealed marked differences in CD8+ T cell infiltration and cytotoxic activity between the high and low cDC1 signature groups. Additionally, the high cDC1 signature group was strongly associated with upregulated expression of immune checkpoint proteins and the activation of oncogenic pathways, indicating a highly immunosuppressive tumor microenvironment. Conclusions: This study suggests that the cDC1-related gene signature may serve as a potent prognostic biomarker in gastric cancer, offering new insights into the complex interactions between the tumor and immune microenvironment. These results could pave the way for innovative therapeutic strategies that target the immune landscape in gastric cancer, potentially improving patient outcomes. Citation Format: Song-hee han. The Role of cDC1 Gene Signatures in gastric cancer prognosis and immune microenvironment modulation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B028.

Abstract B034: Engineering the tumor microenvironment: Patient-specific microphysiological systems of the head and neck cancer tumor microenvironment

Abstract Introduction: Survival rates in advanced head and neck cancer (HNC) remain poor with no clinically approved biomarkers to predict treatment efficacy. HNC is a highly heterogenous disease and the lack of available models that capture patient heterogeneity and the complexity of the tumor microenvironment (TME) contributes to these poor patient outcomes. Microphysiological systems (MPS) are complex multicellular in vitro models that can recapitulate three-dimensional organ structure and function. The low cell number requirements for MPS permits the creation of patient-specific TME models, where all the cell types can be isolated from a single piece of tumor tissue. These patient-specific MPS represent a promising strategy for elucidating the contribution of the TME to treatment resistance, predicting the best treatment for each patient and improving patient outcomes in HNC. Here, we report a patient-specific MPS that contains multiple TME compartments and recapitulates patient heterogeneity. Methods: Tumor tissue was collected from patients with oral cavity carcinoma undergoing standard of care surgery followed by radiation or chemoradiation. Tissue from each patient was digested and tumor infiltrating leukocytes (TIL) were isolated using CD45 magnetic beads, while epithelial cells and fibroblasts were expanded in culture using specific media formulations. Tissue was also snap frozen for single cell RNA sequencing analysis. To build the MPS, a custom designed microfluidic device was filled with a hydrogel matrix containing patient-matched TIL, fibroblasts and epithelial spheroids to mimic the solid tumor. Lumens molded from the hydrogel were seeded with blood or lymphatic endothelial cells to create vasculature. Multiple replicate MPS can be built from each patient, which are cultured in an optimized media formulation to support the multiple primary cell types. Patient-specific MPS were treated with radiation or cisplatin + radiation to mimic the treatment the patient received. Multiple orthogonal endpoints were measured including tumor cell migration and viability, cytokine secretion and angiogenesis. Single cell sequencing was also performed on the original tumor tissue and matched MPS. Results: We have successfully created patient-specific models of the HNC TME. Single cell RNA sequencing analysis of the MPS suggests that cellular heterogeneity is being retained. Patient characteristics varied between MPS with some patient TME MPS showing highly migratory tumor cells or angiogenic responses. Treatment responses were measured for each patient-specific MPS and ongoing work will characterize the contributions of the TME to treatment resistance. These data demonstrate the feasibility of using patient-specific MPS to investigate the contribution of the TME to treatment response and resistance and lays important groundwork for using MPS to identify patient treatment responses. Citation Format: Adeel Ahmed, Marcos Lares, Fauzan Ahmed, Adam R. Burr, Paul M. Harari, David J. Beebe, Sheena C. Kerr. Engineering the tumor microenvironment: Patient-specific microphysiological systems of the head and neck cancer tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B034.

Abstract C021: Tumor-associated microbiota suppresses anti-tumor immunity by driving cDC1 dysfunction in lung cancer

Abstract Type 1 conventional dendritic cells (cDC1s) are critical for initiating and sustaining tumor-reactive CD8 T cells; lack of functional cDC1s is a key driver for failed tumor immunosurveillance and immunotherapy. However, what factors cause the cDC1 insufficiency in the tumor microenvironment (TME) remain poorly understood. Commensal microbiota has emerged as a key regulator of TME and the efficacy of cancer immunotherapies. Nonetheless, most studies have focused on the intestinal microbiome; it remains underexplored whether and how the local microbiota within tumors influences the anti-cancer immunity. Using the autochthonous Kras LSL-G12D/+ ; p53 flox/flox (KP) mouse model of lung cancer, we found an increased local bacterial burden and altered bacterial composition associated with lung tumors. Importantly, this local microbiota suppresses the anti-tumor CD8 T cell response both at baseline and in response to ICB therapies. Specifically, single-cell RNA-seq analysis revealed that the microbiota shapes the functional subsets of tumor-reactive CD8 T cells. Bacterial depletion promotes the accumulation of stem-like Tpex cells (precursor of exhausted T cells) in the TME, which serve as a reservoir of effector CD8 T cells and mediate an effective response upon ICB treatment. To distinguish the function of the local microbiota within TME from the distal gut microbiota, we developed a new method of aerosolized antibiotic treatment, which selectively ablates the intra-tumoral lung microbiota while preserving the intact gut microbiota. Using this approach, we demonstrated that removal of the intra-tumoral lung microbiota markedly improves the tumor-reactive T cell response and sensitizing “cold” lung tumors to ICB therapies. Mechanistically, we identified cDC1s as a central player in microbiota-mediated suppression of anti-tumor immunity. Local microbiota diminishes cDC1 quality and quantity in the lung TME, resulting in impaired T cell priming and Tpex maintenance. At the molecular level, our data revealed that bacterial products derived from the local microbiota induce type I interferon expression in tumor-associated myeloid cells and enhance GM-CSF production from cancer cells: chronic type I interferon and GM-CSF signaling acts cooperatively to reduce the functional cDC1 population. Combining in vitro cDC1 assays, competitive bone marrow chimera experiments and cDC1-specific knockout models, we establish the causal relationships between the local microbiota, IFN-I and GM-CSF signaling in cDC1s, and the tumor response to ICB. Altogether, our study uncovered a dominant role of tumor-associated microbiota in inhibiting cDC1s and suppressing anti-tumor immunity through type I IFN and GM-CSF dependent pathways in lung cancer. Our findings not only identify the intra-tumoral microbiota as a critical therapeutic target for lung cancer treatment, but also provide new insights into the tissue-specific, context-dependent regulatory mechanisms of cDC1s in the TME. Citation Format: Qiang Dong, Chengcheng Jin. Tumor-associated microbiota suppresses anti-tumor immunity by driving cDC1 dysfunction in lung cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C021.

Abstract B037: Expression of MRTFA facilitates an immunosuppressive tumor microenvironment via upregulation of VSIR

Abstract Breast cancer, the second highest cause of cancer-related deaths in women, accounts for 31% of female cancer diagnoses. African American women have lower survival rates than White American women, influenced by both biological factors (age, family history, genetic factors, tumor biology) and social determinants (socio-economic status, insurance status, health care access). However, precise biological determinants remain unclear. The primary reason for breast cancer mortality is metastasis to organs like the lung, liver, and brain, with transcription factors playing a key role in this process. Myocardin related transcription factor A/B (MRTFA/B) are co-activators of serum-response factor (SRF), and the MRTF-SRF complex promotes breast cancer cell migration, invasion, and metastasis by regulating genes involved in actin cytoskeleton remodeling. MRTFA also supports tumor growth by modulating cancer-associated fibroblasts (CAFs) and remodeling the extracellular matrix (ECM) in the tumor microenvironment. While the pro-metastatic role of MRTFA/B is established in vitro and in mice, their impact on human cancer progression and metastasis requires further investigation. Therefore, understanding MRTFA's role in breast cancer metastasis is crucial for improving patient outcomes, making it essential to investigate MRTFA/B expression patterns in both tumor cells and the tumor microenvironment (TME). To explore the clinical, demographic, tumor-intrinsic, and tumor microenvironmental patterns of MRTFA/B’s expression and activation, we utilized multiplex imaging methods on multiple racially diverse tissue microarrays (TMA) and bioinformatics analyses of The Cancer Genome Atlas (TCGA), Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), and available single-cell RNA sequencing datasets. Strikingly, MRTFA expression levels were higher in African American patients than in White American patients. Next, we investigated MRTFA expression patterns in the TME by using single-cell sequencing databases and found more abundant MRTFA expression in dendritic cells (DCs) within the TME compared to any other cell subtype. Moreover, our multiplex-imaging of tumor microarray (TMA) samples showed prominent MRTFA expression in HLA-DRA+CD45+ cells, indicative of antigen-presenting cells (APC). Notably, public single-cell RNA sequencing data indicated that breast cancer DCs strongly express the V-set immunoregulatory receptor (VSIR), an immune checkpoint protein, implying the immunosuppressive nature of the TME and we found that this increased VSIR expression is mediated by the MRTF-SRF complex. These findings suggest that DCs expressing MRTFA in breast cancer microenvironment contribute to creating the immunosuppressive TME via upregulation of VSIR expression, resulting in racial breast cancer disparities. Citation Format: Kihak Lee, Stephanie M. Wilk, Alexa M. Gajda, Mohamed Haloul, Virgilia Macias, Elizabeth L. Wiley, Zhengjia Chen, Xinyi Liu, Xiaowei Wang, Maria Sverdlov, Kent F. Hoskins, Ekrem Emrah Er. Expression of MRTFA facilitates an immunosuppressive tumor microenvironment via upregulation of VSIR [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B037.

Abstract C033: Identifying and targeting prostate cancer therapy resistance mechanisms driven by the tumor microenvironment

Abstract Background: Prostate cancer is a prevalent malignancy in men, with treatment resistance posing a significant challenge to successful cure. Acquired Resistance to Therapy (ART) arises from two main components: (1) Tumor Microenvironment (TME) and (2) mutations or epigenetic changes at gene level within the tumor cells themselves. While most cancer therapies target the intrinsic biology of cancer cells, growing evidence indicates that these treatments can also harm the stromal cells within TME, potentially driving ART. The biology of ART may vary based on the types of treatments, cell types, and organ locations. Thus, this study aims to dissect ART components driven by TME-mediated cellular processes in a comprehensive manner. Hypothesis: We propose that cancer therapies induce stress responses in non-cancerous cells within the TME. These stress responses involve the secretion of cytokines, mediators, and growth factors, which we term Stress Response Secretory Programs (SRSPs). We further hypothesize that targeting SRSPs could overcome ART that helps to improve treatment specificity and efficacy. Materials and Methods: We employed comprehensive single-cell profiling of common metastatic sites included liver, prostate, lung, bone, lymph node and spleen in preclinical models to identify secreted proteins and dysregulated pathways caused by genotoxic therapies. In vitro, we evaluated treatment resistance in murine prostate epithelial cell lines (Myc-CAP) by exposing them to conditioned media (CM) from irradiated murine fibroblasts (F4M2), using cell growth assays. Results: Single-cell RNA sequencing of organ samples revealed significant expressions of SRSPs and increased inflammatory responses in liver and prostate fibroblasts as well as other stromal cells treated with carboplatin. In vitro, CM from irradiated F4M2 cells enhanced cell proliferation and survival of Myc-CAP cells in response to docetaxel treatment. Conclusion: Our findings highlight the crucial role of SRSPs in mediating ART through interactions within the TME, which alter tumor cell phenotypes. Targeting these SRSPs holds potential for overcoming treatment resistance and improving therapeutic outcomes, underscoring the need to consider TME complexity in cancer treatment strategies. Citation Format: Tony Lok Heng Chu, Armand Bankhead, Ilsa Coleman, Sander Frank, Peter S. Nelson, Tarana Arman. Identifying and targeting prostate cancer therapy resistance mechanisms driven by the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C033.