Antitumor Immunity In Colorectal Cancer Research Articles

Ganoderma lucidum Polysaccharide Supplementation Significantly Activates T-Cell-Mediated Antitumor Immunity and Enhances Anti-PD-1 Immunotherapy Efficacy in Colorectal Cancer.

Ganoderma lucidum polysaccharide (GLP) is a prebiotic with immunomodulatory effects. However, the therapeutic potential of GLP in tumor immunotherapy has not been fully explored, especially in T cell-mediated antitumor immunity. In this study, we found that GLP significantly inhibited tumor growth and activated antitumor immunity in colorectal cancer (CRC). In the spleens and tumor tissues, the proportion of cytotoxic CD8+T cells and Th1 helper cells increased, while immunosuppressive Tregs decreased. Additionally, microbiota dysbiosis was alleviated by GLP, and short-chain fatty acid production was increased. Meanwhile, GLP decreased the ratio of kynurenine and tryptophan (Kyn/Trp) in the serum, which contributed to antitumor immunity of T cells. More importantly, the combination of GLP and the immune checkpoint inhibitor anti-PD-1 monoclonal antibody further enhanced the efficacy of anti-PD-1 immunotherapy. Thus, GLP as a prebiotic has the potential to be used in tumor immunotherapy.

Abstract LB349: Cysteine restriction enhances antitumor immunity in colorectal cancer

Abstract Background: Colon cancer is the second leading cause of cancer mortality worldwide, however, there are still issues with multidrug resistance and severe adverse reactions. Previous studies have shown that sulfur-containing amino acids are involved in cancer development, drug resistance, and immune evasion. Here, Our experimental findings suggested that restricting the intake of sulfur-containing amino acids may present a novel strategy for treating colorectal cancer. Methods: We assessed the impact of sulfur-containing amino acid restriction (SAR) on distinct cellular subpopulations within the tumor microenvironment through single-cell sequencing on colon carcinogenesis induced by azoxymethane/dextran sodium sulfate (AOM/DSS). Employing our custom-produced neutralizing antibodies against SLC7A11 to restrict cysteine intake, we examined the therapeutic implications and underlying molecular mechanisms by RNA-seq, Multiplexed immunofluorescence staining and Western blotting. Results: In the AOM/DSS model, SAR led to a slight reduction in mouse body weight compared to the normal diet. However, this dietary restriction significantly enhanced the survival rate of mice and effectively suppressed tumor growth. The single-cell sequencing results indicated a significant increase in the proportion of T cells within the tumor microenvironment in response to SAR. This suggested that restricting the intake of sulfur-containing amino acids may be a promising anti-tumor strategy. Previous studies have indicated high expression of the SLC7A11, a cysteine transporter protein, in various cancers, including colorectal cancer. To further investigate the role of cysteine in colorectal cancer, we developed the neutralizing antibody 1A4 against SLC7A11. Our results indicated that 1A4 markedly inhibited colorectal cancer development in mice. As known, 85% of colorectal cancers are microsatellite stable, which hardly benefit from treatment with immune checkpoint inhibitors (ICIs). Compared to anti-PD-1 and anti-CTLA4, 1A4 significantly inhibited the growth of CT26 in vivo. Multiplexed immunofluorescence staining results demonstrated that 1A4 significantly increased the proportion of CD8+ T cells in colorectal cancer tissues. Conclusion: Limiting cysteine intake significantly inhibits the growth of colorectal cancer, increases the proportion of CD8+ T cells, and enhances anti-tumor immunity. Citation Format: Jichang Li, Kang Xia, Zeruo Yang, Xiaoxue Pan, Xiaojing Yang, Pengyuan Wang, Shanwen Chen. Cysteine restriction enhances antitumor immunity in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB349.

Deubiquitinase USP4 suppresses antitumor immunity by inhibiting IRF3 activation and tumor cell-intrinsic interferon response in colorectal cancer

Despite the approval of immune checkpoint blockade (ICB) therapy for various tumor types, its effectiveness is limited to only approximately 15% of patients with microsatellite instability-high (MSI-H) or mismatch repair deficiency (dMMR) colorectal cancer (CRC). Approximately 80%–85% of CRC patients have a microsatellite stability (MSS) phenotype, which features a rare T-cell infiltration. Thus, elucidating the mechanisms underlying resistance to ICB in patients with MSS CRC is imperative. In this study, we demonstrate that ubiquitin-specific peptidase 4 (USP4) is upregulated in MSS CRC tumors and negatively regulates the immune response against tumors in CRC. Additionally, USP4 represses the cellular interferon (IFN) response and antigen presentation and impairs PRR signaling-mediated cell death. Mechanistically, USP4 impedes the nuclear localization of interferon regulator Factor 3 (IRF3) by deubiquitinating the K63-polyubiquitin chain of TRAF6 and IRF3. Knockdown of USP4 enhances the infiltration of T cells in CRC tumors and overcomes ICB resistance in an MC38 syngeneic mouse model. Moreover, published datasets revealed that patients showing higher USP4 expression exhibited decreased responsiveness to anti-PD-L1 therapy. These findings highlight an essential role of USP4 in the suppression of antitumor immunity in CRC.

The C-type lectin DCIR contributes to the immune response and pathogenesis of colorectal cancer

Development and progression of malignancies are accompanied and influenced by alterations in the surrounding immune microenvironment. Understanding the cellular and molecular interactions between immune cells and cancer cells has not only provided important fundamental insights into the disease, but has also led to the development of new immunotherapies. The C-type lectin Dendritic Cell ImmunoReceptor (DCIR) is primarily expressed by myeloid cells and is an important regulator of immune homeostasis, as demonstrated in various autoimmune, infectious and inflammatory contexts. Yet, the impact of DCIR on cancer development remains largely unknown. Analysis of available transcriptomic data of colorectal cancer (CRC) patients revealed that high DCIR gene expression is associated with improved patients’ survival, immunologically "hot" tumors and high immunologic constant of rejection, thus arguing for a protective and immunoregulatory role of DCIR in CRC. In line with these correlative data, we found that deficiency of DCIR1, the murine homologue of human DCIR, leads to the development of significantly larger tumors in an orthotopic murine model of CRC. This phenotype is accompanied by an altered phenotype of tumor-associated macrophages (TAMs) and a reduction in the percentage of activated effector CD4+ and CD8+ T cells in CRC tumors of DCIR1-deficient mice. Overall, our results show that DCIR promotes antitumor immunity in CRC, making it an attractive target for the future development of immunotherapies to fight the second deadliest cancer in the world.

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.

Pharmacological suppression of HHLA2 glycosylation restores anti-tumor immunity in colorectal cancer

Immunotherapy aimed at inhibiting the negative co-stimulatory molecule programmed cell death-ligand 1 (PD-L1) has limited effectiveness, with clinical response rates remaining below 10%–15%. Therefore, new immune checkpoints need to be explored. Our study focused on human endogenous retrovirus H long terminal repeat–associating protein 2 (HHLA2), a highly glycosylated member of the B7 family that is widely expressed in colorectal cancer. HHLA2 expression negatively correlates with the prognosis of colorectal cancer. Glycosylation of HHLA2, which is regulated by the glycosyltransferase STT3 oligosaccharyltransferase complex catalytic subunit A (STT3A), is crucial for protein stability and expression in cell membranes. Additionally, the binding of HHLA2 to the receptors killer cell immunoglobulin-like receptor, three immunoglobulin domains and long cytoplasmic tail 3 (KIR3DL3) and transmembrane and immunoglobulin (Ig) domain containing 2 (TMIGD2) is dependent on N-glycosylation. Moreover, N-glycosylation of HHLA2 promotes immune evasion in colorectal cancer by suppressing the immune response of NK cells. Notably, the STT3A inhibitor NGI-1 enhances the anti-tumor immune response of NK cells. Our findings provide new insights and a molecular basis for targeting HHLA2 in immunotherapy for colorectal cancer.

Arenobufagin Enhances T-cell Anti-Tumor Immunity in Colorectal Cancer by Modulating HSP90β Accessibility

BackgroundColorectal cancer (CRC) is a significant public health issue, ranking as one of the predominant cancer types globally in terms of incidence. Intriguingly, Arenobufagin(Are), a compound extracted from toad venom, has demonstrated the potential to inhibit tumor growth effectively. PurposeThis study aimed to explore Are's molecular targets and unravel its antitumor mechanism in CRC. Specifically, we were interested in its impact on immune checkpoint modulation and correlations with HSP90β-STAT3-PD-L1 axis activity. MethodsWe investigated the in vivo antitumor effects of Are by constructing a colorectalcancer subcutaneous xenograft mouse model. Subsequently, we employed single-cell multi-omics technology to study the potential mechanism by which Are inhibits colorectal cancer. Utilizing Target-responsive accessibility profiling (TRAP) technology, we identified heatshock protein 90p (HSP90β) as the direct target of Are, and confirmed this through a microscale thermophoresis experiment (MST). Further downstream mechanisms were explored through techniques such as co-immunoprecipitation, Western blotting, qPCR, and immunofluorescence. Concurrently, we arrived at the same research conclusion at the organoid level by co-cultivating with immune cells. ResultsWe observed that Are inhibits PD-Ll expression in CRC tumor xenografts at low concentrations. Moreover, TRAP revealed that HSP90p's accessibility significantly decreasedupon Are binding. We demonstrated a decrease in the activity of the HSP908-STAT3-PD-Ll axis following low-concentration Are treatment in vivo. The PDO analysis showed improved enrichment of lymphocytes, particularly T cells, on the PDOs following Are treatment. ConclusionContrary to previous research focusing on the direct cytotoxicity of Arenobufagin towards tumor cells, our findings indicate that it can also inhibit tumor growth at lower concentrations through the modulation of immune checkpoints. This study unveils a novel anti-tumor mechanism of Arenobufagin and stimulates contemplation on the dose-response relationship of natural products, which is beneficial for the clinical translational application of Arenobufagin.

RNA-based modulation of macrophage-mediated efferocytosis potentiates antitumor immunity in colorectal cancer

Tumor-associated macrophages play pivotal roles in tumor progression and metastasis. Macrophage-mediated clearance of apoptotic cells (efferocytosis) supports inflammation resolution, contributing to immune evasion in colorectal cancers. To reverse this immunosuppressive process, we propose a readily translatable RNA therapy to selectively inhibit macrophage-mediated efferocytosis in tumor microenvironment. A clinically approved lipid nanoparticle platform (LNP) is employed to encapsulate siRNA for the phagocytic receptor MerTK (siMerTK), enabling selective MerTK inhibition in the diseased organ. Decreased MerTK expression in tumor-associated macrophages results in apoptotic cell accumulation and immune activation in tumor microenvironment, leading to suppressed tumor growth and better survival in both liver and peritoneal metastasis models of colorectal cancers. siMerTK delivery combined with PD-1 blockade further produces enhanced antimetastatic efficacy with reactivated intratumoral immune milieu. Collectively, LNP-based siMerTK delivery combined with immune checkpoint therapy may present a feasible modality for metastatic colorectal cancer therapy.

Tumor-intrinsic expression of the autophagy gene Atg16l1 suppresses anti-tumor immunity in colorectal cancer

Microsatellite-stable colorectal cancer (MSS-CRC) is highly refractory to immunotherapy. Understanding tumor-intrinsic determinants of immunotherapy resistance is critical to improve MSS-CRC patient outcomes. Here, we demonstrate that high tumor expression of the core autophagy gene ATG16L1 is associated with poor clinical response to anti-PD-L1 therapy in KRAS-mutant tumors from IMblaze370 (NCT02788279), a large phase III clinical trial of atezolizumab (anti-PD-L1) in advanced metastatic MSS-CRC. Deletion of Atg16l1 in engineered murine colon cancer organoids inhibits tumor growth in primary (colon) and metastatic (liver and lung) niches in syngeneic female hosts, primarily due to increased sensitivity to IFN-γ-mediated immune pressure. ATG16L1 deficiency enhances programmed cell death of colon cancer organoids induced by IFN-γ and TNF, thus increasing their sensitivity to host immunity. In parallel, ATG16L1 deficiency reduces tumor stem-like populations in vivo independently of adaptive immune pressure. This work reveals autophagy as a clinically relevant mechanism of immune evasion and tumor fitness in MSS-CRC and provides a rationale for autophagy inhibition to boost immunotherapy responses in the clinic.

Orchestrated copper-based nanoreactor for remodeling tumor microenvironment to amplify cuproptosis-mediated anti-tumor immunity in colorectal cancer

Owing to the deficiency of infiltrating immune cells and the accumulation of immunosuppressive cells in tumor microenvironment (TME), immunotherapy remains enormous challenges in colorectal cancer (CRC). Here, CRC was found to be sensitive to cuproptosis which could further evoke immune responses and mediate immune resistance. Thus, a cuproptosis-mediated immunotherapy nanoreactor (CCJD-FA) was constructed by encapsulating copper-based shell-coated CaO2 and bromodomain-containing protein 4 inhibitor JQ-1 with DSPE-PEG-FA. Within tumor cells, CCJD-FA was disassembled under GSH environment, and the exposed CaO2 could generate H2O2 under the acidic condition, which reacted with the released Cu2+ via Fenton-like reaction to produce O2 for relieving hypoxia and Cu+ for inducing cuproptosis. Furthermore, CCJD-FA could also inhibit intracellular glycolysis and ATP generation, then blocking the Cu+ efflux protein ATP7B. Meanwhile, the IFN-γ-induced PD-L1 expression could be exactly reduced by the BRD4 suppression and oxygen supply. These effects sensitized cancer cells to cuproptosis, further evoking systemic immune responses and reshaping immunosuppressive TME to inhibit tumor growth.

Microbial regulation of anti-tumor immunity in colorectal cancer

Abstract Colorectal cancer (CRC) is one of the most common and deadly types of cancer. Although recent advances in early detection and revolutionary therapies such as checkpoint blockade immunotherapy resulted in improved outcomes in CRC, a large fraction of CRC patients, particularly with metastasis, do not respond well to existing immunotherapy modalities. This necessitates a better mechanistic understanding on tumor – immune cell interactions in the context of CRC. Microbiome influences multiple biological aspects of the host including immune responses against cancers. We recently defined a causal role for microbiome in regulating epithelial stem cell MHC-II expression and tumor initiation in the intestine. Here we expound on the significance of microbiome - MHC-II axis in CRC progression and metastasis. We found that colonization of microbes that correlate epithelial MHC-II expression in the intestine restricts CRC progression and improves overall survival in three different clinically-relevant orthotopic CRC models across mice strains. Notably, microbiome-induced anti-tumor effects are dependent on T cells. Finally, genetic inactivation of MHC-II in cancer cells diminished tumor preventing effects of microbes. These results underscore a causal role for microbe - MHC-II axis in regulating anti-tumor immunity during tumor progression. Microbes that boost MHC-II expression promote anti-tumor immunity in the colon, which may synergize with therapeutic approaches such as immunotherapy. NIH (P30CA045508-33 to S.B.), the Oliver S. and Jennie R. Donaldson Charitable Trust (S.B.), The Harold and Leila Y. Mathers Charitable Foundation (S.B), The Mark Foundation for Cancer Research (20-028-EDV to S.B.) and STARR Cancer Consortium (I13-0052 to S.B.), Chan Zuckerberg Initiative / Silicon Valley Community Foundation (2021-239862)

Microwave ablation induces abscopal effect via enhanced systemic antitumor immunity in colorectal cancer.

Thermal ablation is the primary procedure for the local treatment of lung metastases. It is known that radiotherapy and cryoablation can stimulate an abscopal effect, while the occurrence of abscopal effect induced by microwave ablation is less; the cellular and molecular mechanisms involved in the abscopal effect after microwave ablation should be further elucidated. CT26 tumor-bearing Balb/c mice were treated with microwave ablation with several combinations of ablation power and time duration. The growth of primary or abscopal tumors and the survival of mice were both monitored; moreover, immune profiles in abscopal tumors, spleens, and lymph nodes were examined by flow cytometry. Microwave ablation suppressed tumor growth in both primary and abscopal tumors. Both local and systemic T-cell responses were induced by microwave ablation. Furthermore, the mice exhibiting significant abscopal effect after microwave ablation markedly elevated Th1 cell proportion both in the abscopal tumors and spleens. Microwave ablation at 3 w-3 min not only suppressed tumor growth in the primary tumors but also stimulated an abscopal effect in the CT26-bearing mice via the improvement of systemic and intratumoral antitumor immunity.

Exosomal lncRNA HOTAIR induces PDL1+ B cells to impede anti-tumor immunity in colorectal cancer

Regulatory B cells (Bregs) contribute to tumor immunosuppression. However, how B cells acquire their regulatory features in tumors remain unclear. Exosomes are important messengers that transmit tumor information to remodel tumor immunity. Here we revealed that tumor-derived exosomes drive Bregs to suppress anti-tumor immunity by delivering long non-coding RNAs (lncRNAs). HOTAIR was screened by lncRNA profiling in both colorectal cancer (CRC)-derived exosomes and infiltrating B cells. Tumor-derived HOTAIR polarized B cells toward a regulatory feature marked by programmed cell death-ligand 1 (PDL1) in CRC, and induced PDL1+ B cells to suppress CD8+ T cell activity. Exosomal HOTAIR bound to and protected pyruvate kinase M2 (PKM2) against ubiquitination degradation, resulting in STAT3 activation and PDL1 expression. Results from CRC patients showed a positive correlation between exosomal HOTAIR and tumor-infiltrating PDL1+ B cells. These findings reveal how B cells acquire PDL1-dominant regulatory feature in CRC, implying the clinical significance of exosomal therapy targeting HOTAIR.

Complement downregulation promotes an inflammatory signature that renders colorectal cancer susceptible to immunotherapy

Background and aimsThe role of inflammatory immune responses in colorectal cancer (CRC) development and response to therapy is a matter of intense debate. While inflammation is a known driver of...

Dopamine Signaling Promotes Tissue-Resident Memory Differentiation of CD8+ T Cells and Antitumor Immunity.

Identification of an immunostimulatory function of dopamine signaling by promoting tissue-resident memory T-cell differentiation and sustaining T-cell effector functions reveals potential therapeutic strategies and prognostic biomarkers for colorectal cancer.

Leucine Dieting Inhibits Immunosuppressive B Cells in Colorectal Cancer

A leucine-dependent regulatory B-cell population hinders antitumor immunity in colorectal cancer.

Associations of different immune checkpoints-expressing CD4+ Treg/ T cell subsets with disease-free survival in colorectal cancer patients

There are different subsets of T regulatory cells (Tregs), orchestrating critical roles in the regulation of anti-tumor immunity in colorectal cancer (CRC). In this study, we report that a high frequency of circulating CD4+FoxP3+ Tregs was associated with poorer disease-free survival (DFS), while their higher frequencies in tumor-infiltrating CD4+ Tregs was associated with better DFS. We further investigated such associations with four Tregs/T cells expressing or lacking FoxP3 and Helios (FoxP3±Helios±). For the first time, we report that a high frequency of circulating CD4+FoxP3+Helios+ Tregs was associated with poorer DFS, while a high frequency of tumor-infiltrating CD4+FoxP3−Helios− T cells was associated with poorer DFS. In the four FoxP3±Helios± T cell subsets expressing any of the immune checkpoints (ICs) investigated, we found that a high frequency of CD4+FoxP3+Helios−PD-1+ Tregs in circulation was associated with worse DFS. We also found that high frequencies of FoxP3+Helios+CTLA-4+ Tregs, FoxP3+Helios−CTLA-4+ Tregs, and FoxP3−Helios+CTLA-4+ CD4+ T cells in circulation were associated with worse DFS. In contrast, high frequencies of CD4+TIM-3+ T cells, FoxP3+Helios+TIM-3+ Tregs, and FoxP3−Helios+TIM-3+ CD4+ T cells in circulation were associated with longer DFS. Our data show that certain CD4+ Treg/T cell subsets could serve as independent predictive biomarkers in CRC patients. Identification of the exact subpopulations contributing to clinical outcomes is critical for prognoses and therapeutic targeting.

Complement downregulation promotes an inflammatory signature that renders colorectal cancer susceptible to immunotherapy

Abstract The role of inflammation in colorectal cancer (CRC) development and response to therapy is highly debated. While inflammation is a known driver of CRC, inflammatory immune infiltrates are a positive prognostic factor in CRC as inflammation can enhance response to immune checkpoint blockade (ICB) therapy. Yet, the majority of CRC are poorly infiltrated and even in presence of an inflammatory infiltrate half of these cancers become refractory to ICB. Therefore, there is a need to identify mechanisms to establish therapy supportive inflammation. We have previously reported that certain patients with CRC down-regulate the receptor for the complement anaphylatoxin C3a (C3aR). The complement system is a first line of defense against pathogens and a central component of the immune response. Emerging evidence suggests that C3aR may play a role in intestinal homeostasis. However, to date, it is unknown how C3aR affects CRC development and response to therapy with ICB. Using our novel mouse model of CRC (APCMin/+/C3aR−/−) we showed that loss of C3aR results in enhanced immune infiltration in typically “cold” tumors and changes in the intestinal microbiota. Similarly, we found that down-regulation of the complement C3aR in patients correlates with changes in specific tumor-infiltrating immune cells. Notably, when treated with a-PD1, APCMin/+/C3aR−/− mice showed a significant reduction of tumors, suggesting that the loss of C3aR unleashes in the colon a microbiota-mediated immune response that can be exploited for therapeutic purposes. Our findings reveal that C3aR may act as a previously unrecognized checkpoint to enhance antitumor immunity in CRC and that C3aR inhibition may be used to overcome ICB resistance in a larger group of CRC patients. This project was supported in part by NIH P20 GM120475 (core facility) at the MUSC Digestive Disease Research Core Center.

Tumor stem cell-derived exosomal microRNA-17-5p inhibits anti-tumor immunity in colorectal cancer via targeting SPOP and overexpressing PD-L1

Exosomes are known to transmit microRNAs (miRNAs) to affect human cancer progression, and miR-17-5p has been manifested to exert facilitated effects on colorectal cancer (CRC) progression, while the role of tumor stem cells-derived exosomal miR-17-5p in CRC remains unknown. We aim to explore the effect of CRC stem cells-derived exosomes (CRCSC-exos) conveying miR-17-5p on CRC. The exosomes were isolated from CRC stem cells and identified. HCT116 cells were transfected with speckle-type POZ protein (SPOP) interfering vector or co-cultured with exosomes carrying miR-17-5p mimic/inhibitor. Then, the proliferation, migration, invasion, and apoptosis of the cells were determined. The xenograft mouse model was constructed using BALB/C mice and the serum levels of T cell cytokines were assessed. Expression of miR-17-5p, SPOP, CD4, CD8 and programmed death ligand 1 (PD-L1) was detected. The targeting relationship between miR-17-5p and SPOP was verified. MiR-17-5p was upregulated and SPOP was downregulated in CRC tissues. CRCSC-exos transmitted miR-17-5p to HCT116 cells to promote malignant behaviors and suppress anti-tumor immunity of HCT116 cells. The overexpressed SPOP exerted opposite effects. SPOP was confirmed as a target gene of miR-17-5p. Upregulated CRCSC-exosomal miR-17-5p inhibits SPOP to promote tumor cell growth and dampen anti-tumor immunity in CRC through promoting PD-L1.

Multiplexed single-cell analysis reveals prognostic and nonprognostic T cell types in human colorectal cancer.

Clinical outcomes in colorectal cancer (CRC) correlate with T cell infiltrates, but the specific contributions of heterogenous T cell types remain unclear. To investigate the diverse function of T cells in CRC, we profiled 37,931 T cells from tumors and adjacent normal colon of 16 patients with CRC with respect to transcriptome, TCR sequence, and cell surface markers. Our analysis identified phenotypically and functionally distinguishable effector T cell types. We employed single-cell gene signatures from these T cell subsets to query the TCGA database to assess their prognostic significance. We found 2 distinct cytotoxic T cell types. GZMK+KLRG1+ cytotoxic T cells were enriched in CRC patients with good outcomes. GNLY+CD103+ cytotoxic T cells with a dysfunctional phenotype were not associated with good outcomes, despite coexpression of CD39 and CD103, markers that denote tumor reactivity. We found 2 distinct Treg subtypes associated with opposite outcomes. While total Tregs were associated with good outcomes, CD38+ Tregs were associated with bad outcomes independently of stage and possessed a highly suppressive phenotype, suggesting that they inhibit antitumor immunity in CRC. These findings highlight the potential utility of these subpopulations in predicting outcomes and support the potential for novel therapies directed at CD38+ Tregs or CD8+CD103+ T cells.