Poor Prognosis In Human Colorectal Cancer Research Articles

Abstract 1393: Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive colorectal cancer

Abstract Mesenchymal subtype of colorectal cancer (CRC) is characterized by high metastatic potential, poor prognosis and an immunosuppressive tumor microenvironment (TME). Although tumor-infiltrating myeloid cells constitute the primary population of immune components in the TME, targeting myeloid cells remains highly challenging owing to the developmental and functional heterogeneity of their subsets. Thus, a deeper understanding of how tumor-infiltrating myeloid cells contribute to the creation of a tumor-promoting TME is needed to identify rational strategies against CRCs with aggressive phenotypes. Recent studies have revealed that multiple inflammatory signatures are elevated in mesenchymal CRCs, suggesting a strong association between inflammation and stromal activation. In this study, we focus on thrombospondin-1 (THBS1), which is a matricellular protein, typically expressed in inflammatory processes. Immunostaining and RNA in situ hybridization on human CRC samples revealed a clear localization of THBS1 expression in tumor stroma. Analyses of the cancer genome atlas (TCGA) and tissue microarray of human CRCs show a positive correlation between increased expression of THBS1 and the mesenchymal phenotype, immunosuppression, and poor prognosis in human CRCs. Utilizing immunocompetent orthotopic implantation systems with aggressive mouse tumor organoids (MTO) on wild-type and Thbs1 knockout (Thbs1−/−) mice, we demonstrated that loss of THBS1 in the TME suppressed metastatic formation accompanied by an increased infiltration of tumor-infiltrating CD8+ T cells. Depletion of CD8+ T cells by neutralizing antibody restored metastases in MTO-bearing Thbs1−/− mice, indicating that THBS1 promotes metastatic formation by suppressing CD8+ T cell-mediated anti-tumor immunity. Analyses of single cell RNA sequencing data of human CRCs and orthotopic MTO tumors revealed that bone marrow (BM)-derived monocyte-like cells are the primary source of THBS1. This notion was further supported by analyzing the orthotopic MTO tumors in chimeric mice generated by bone marrow transplantation. Finally, we identified stroma-derived CXCL12 as a key chemokine for the recruitment of THBS1-producing monocyte-like cells by analyzing orthotopic MTO tumors treated with CXCL12 inhibitor. Our study contributes to a better understanding of the processes underlying THBS1 production by monocyte-like cells that mediates immune evasion that confer aggressive features to CRCs. These findings provide insights for the treatment of this poor-prognosis malignancy. Citation Format: Mayuki Omatsu, Yuki Nakanishi, Kosuke Iwane, Naoki Aoyama, Takahisa Maruno, Hiroaki Kasashima, Masakazu Yashiro, Akihisa Fukuda, Hiroshi Seno. Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive 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 1393.

Cathepsin C promotes colorectal cancer metastasis by regulating immune escape through upregulating CSF1.

Since metastasis remains the primary reason for colorectal cancer (CRC) associated death, a better understanding of the molecular mechanism underlying CRC metastasis is urgently needed. Here, we elucidated the role of Cathepsin C (CTSC) in promoting CRC metastasis. The expression of CTSC was detected by real-time PCR and immunohistochemistry in the human CRC cohort. The metastatic capacities of CTSC-mediated metastasis were analyzed by in vivo metastasis model. Elevated CSTC expression was positively associated with tumor differentiation, tumor invasion, lymph node metastasis, and AJCC stage and indicated poor prognosis in human CRC. CTSC overexpression in CRC cells promoted myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) recruitment by the CSF1/CSF1R axis. In contrast, the knockdown of CSF1 reduced CTSC-mediated MDSCs and TAMs infiltration and CRC metastasis. Depletion of either MDSCs or TAMs decreased CTSC-mediated CRC metastasis. In human CRC tissues, CTSC expression was positively associated with intratumoral MDSCs and TAMs infiltration. Furthermore, the combination of CTSC inhibitor AZD7986 and anti-PD-L1 antibody blocked CTSC-induced CRC metastasis. CTSC overexpression promoted MDSCs and TAMs infiltration by CSF1/CSF1R axis. Interruption of this oncogenic loop may provide a promising treatment strategy for inhibiting CTSC-driven CRC metastasis.

Galectin-1 fosters an immunosuppressive microenvironment in colorectal cancer by reprogramming CD8+ regulatory T cells

Colorectal cancer (CRC) represents the third most common malignancy and the second leading cause of cancer-related deaths worldwide. Although immunotherapy has taken center stage in mainstream oncology, it has shown limited clinical efficacy in CRC, generating an urgent need for discovery of new biomarkers and potential therapeutic targets. Galectin-1 (Gal-1), an endogenous glycan-binding protein, induces tolerogenic programs and contributes to tumor cell evasion of immune responses. Here, we investigated the relevance of Gal-1 in CRC and explored its modulatory activity within the CD8+ regulatory T cell (Treg) compartment. Mice lacking Gal-1 (Lgals1-/- ) developed a lower number of tumors and showed a decreased frequency of a particular population of CD8+CD122+PD-1+ Tregs in the azoxymethane-dextran sodium sulfate model of colitis-associated CRC. Moreover, silencing of tumor-derived Gal-1 in the syngeneic CT26 CRC model resulted in reduced number and attenuated immunosuppressive capacity of CD8+CD122+PD-1+ Tregs, leading to slower tumor growth. Moreover, stromal Gal-1 also influenced the fitness of CD8+ Tregs, highlighting the contribution of both tumor and stromal-derived Gal-1 to this immunoregulatory effect. Finally, bioinformatic analysis of a colorectal adenocarcinoma from The Cancer Genome Atlas dataset revealed a particular signature characterized by high CD8+ Treg score and elevated Gal-1 expression, which delineates poor prognosis in human CRC. Our findings identify CD8+CD122+PD-1+ Tregs as a target of the immunoregulatory activity of Gal-1, suggesting a potential immunotherapeutic strategy for the treatment of CRC.

Autocrine WNT2 signaling in fibroblasts promotes colorectal cancer progression.

The canonical WNT signaling pathway is crucial for intestinal stem cell renewal and aberrant WNT signaling is an early event in colorectal cancer (CRC) development. Here, we show for the first time that WNT2 is one of the most significantly induced genes in CRC stroma as compared to normal stroma. The impact of stromal WNT2 on carcinoma formation or progression was not addressed so far. Canonical WNT/β-catenin signaling was assessed using a 7TGP-reporter construct. Furthermore, effects of WNT2 on fibroblast migration and invasion were determined using siRNA-mediated gene silencing. Tumor cell invasion was studied using organotypic raft cultures and in vivo significance was assessed via a xenograft mouse model. We identified cancer-associated fibroblasts (CAFs) as the main source of WNT2. CAF-derived WNT2 activated canonical signaling in adenomatous polyposis coli/β-catenin wild-type colon cancer cells in a paracrine fashion, whereas no hyperactivation was detectable in cell lines harboring mutations in the adenomatous polyposis coli/β-catenin pathway. Furthermore, WNT2 activated autocrine canonical WNT signaling in primary fibroblasts, which was associated with a pro-migratory and pro-invasive phenotype. We identified FZD8 as the putative WNT2 receptor in CAFs. Three-dimensional organotypic co-culture assays revealed that WNT2-mediated fibroblast motility and extracellular matrix remodeling enhanced cancer cell invasion of cell lines even harboring mutations in the adenomatous polyposis coli/β-catenin pathway. Thus, suggesting a tumor-promoting influence on a broad range of CRC. In line, WNT2 also promotes tumor growth, invasion and metastasis in vivo. Moreover, high WNT2 expression is associated with poor prognosis in human CRC. The identification of the pro-malignant function of stromal derived WNT2 in CRC classifies WNT2 and its receptor as promising stromal targets to confine cancer progression in combination with conventional or targeted therapies.