M6A regulator-mediated methylation modification patterns and tumor microenvironment infiltration characterization in gastric cancer.
ABSTRACT: BACKGROUND:The epigenetic regulation of immune response has been demonstrated in recent studies. Nonetheless, potential roles of RNA N6-methyladenosine (m6A) modification in tumor microenvironment (TME) cell infiltration remain unknown. METHODS:We comprehensively evaluated the m6A modification patterns of 1938 gastric cancer samples based on 21 m6A regulators, and systematically correlated these modification patterns with TME cell-infiltrating characteristics. The m6Ascore was constructed to quantify m6A modification patterns of individual tumors using principal component analysis algorithms. RESULTS:Three distinct m6A modification patterns were determined. The TME cell-infiltrating characteristics under these three patterns were highly consistent with the three immune phenotypes of tumors including immune-excluded, immune-inflamed and immune-desert phenotypes. We demonstrated the evaluation of m6A modification patterns within individual tumors could predict stages of tumor inflammation, subtypes, TME stromal activity, genetic variation, and patient prognosis. Low m6Ascore, characterized by increased mutation burden and activation of immunity, indicated an inflamed TME phenotype, with 69.4% 5-year survival. Activation of stroma and lack of effective immune infiltration were observed in the high m6Ascore subtype, indicating a non-inflamed and immune-exclusion TME phenotype, with poorer survival. Low m6Ascore was also linked to increased neoantigen load and enhanced response to anti-PD-1/L1 immunotherapy. Two immunotherapy cohorts confirmed patients with lower m6Ascore demonstrated significant therapeutic advantages and clinical benefits. CONCLUSIONS:This work revealed the m6A modification played a nonnegligible role in formation of TME diversity and complexity. Evaluating the m6A modification pattern of individual tumor will contribute to enhancing our cognition of TME infiltration characterization and guiding more effective immunotherapy strategies.
Project description:Recent studies have highlighted the biological significance of RNA N<sup>6</sup>-methyladenosine (m<sup>6</sup>A) modification in tumorigenicity and progression. However, it remains unclear whether m<sup>6</sup>A modifications also have potential roles in immune regulation and tumor microenvironment (TME) formation. <b>Methods</b>: In this study, we curated 23 m<sup>6</sup>A regulators and performed consensus molecular subtyping with NMF algorithm to determine m<sup>6</sup>A modification patterns and the m<sup>6</sup>A-related gene signature in colon cancer (CC). The ssGSEA and CIBERSORT algorithms were employed to quantify the relative infiltration levels of various immune cell subsets. An PCA algorithm based m<sup>6</sup>Sig scoring scheme was used to evaluate the m<sup>6</sup>A modification patterns of individual tumors with an immune response. <b>Results</b>: Three distinct m6A modification patterns were identified among 1307 CC samples, which were also associated with different clinical outcomes and biological pathways. The TME characterization revealed that the identified m<sup>6</sup>A patterns were highly consistent with three known immune profiles: immune-inflamed, immune-excluded, and immune-desert, respectively. Based on the m<sup>6</sup>Sig score, which was extracted from the m<sup>6</sup>A-related signature genes, CC patients can be divided into high and low score subgroups. Patients with lower m<sup>6</sup>Sig score was characterized by prolonged survival time and enhanced immune infiltration. Further analysis indicated that lower m<sup>6</sup>Sig score also correlated with greater tumor mutation loads, PD-L1 expression, and higher mutation rates in SMGs (e.g., <i>PIK3CA</i> and <i>SMAD4</i>). In addition, patients with lower m<sup>6</sup>Sig scores showed a better immune responses and durable clinical benefits in three independent immunotherapy cohorts. <b>Conclusions</b>: This study highlights that m<sup>6</sup>A modification is significantly associated with TME diversity and complexity. Quantitatively evaluating the m<sup>6</sup>A modification patterns of individual tumors will strengthen our understanding of TME characteristics and promote more effective immunotherapy strategies.
Project description:<b>Rationale:</b> Siglec15 is an emerging target for normalization cancer immunotherapy. However, pan-cancer anti-Siglec15 treatment is not yet validated and the potential role of Siglec15 in bladder cancer (BLCA) remains elusive. <b>Methods:</b> We comprehensively evaluated the expression pattern and immunological role of Siglec15 using pan-cancer analysis based on RNA sequencing data obtained from The Cancer Genome Atlas. We then systematically correlated Siglec15 with immunological characteristics in the BLCA tumor microenvironment (TME), including immunomodulators, cancer immunity cycles, tumor-infiltrating immune cells (TIICs), immune checkpoints, and T cell inflamed score. We also analyzed the role of Siglec15 in predicting the molecular subtype and the response to several treatment options in BLCA. Our results were validated in several public cohorts as well as our BLCA tumor microarray cohort, the Xiangya cohort. We developed an immune risk score (IRS), validated it, and tested its ability to predict the prognosis and response to cancer immunotherapy. <b>Results:</b> We found that Siglec15 was specifically overexpressed in the TME of various cancers. We hypothesize that Siglec15 designs a non-inflamed TME in BLCA based on the evidence that Siglec15 negatively correlated with immunomodulators, TIICs, cancer immunity cycles, immune checkpoints, and T cell inflamed score. Bladder cancer with high Siglec15 expression was not sensitive to cancer immunotherapy, but exhibited a higher incidence of hyperprogression. High Siglec15 levels indicated a luminal subtype of BLCA characterized by lower immune infiltration, lower response to cancer immunotherapy and neoadjuvant chemotherapy, but higher response to anti-angiogenic therapy and targeted therapies such as blocking Siglec15, ?-catenin, PPAR-?, and FGFR3 pathways. Notably, a combination of anti-Siglec15 and cancer immunotherapy may be a more effective strategy than monotherapy. IRS can accurately predict the prognosis and response to cancer immunotherapy. <b>Conclusions:</b> Anti-Siglec15 immunotherapy might be suitable for BLCA treatment as Siglec15 correlates with a non-inflamed TME in BLCA. Siglec15 could also predict the molecular subtype and the response to several treatment options.
Project description:BACKGROUND & AIMS:Intrahepatic cholangiocarcinoma (ICC) is asevere malignant tumor in which the standard therapies are mostly ineffective. The biological significance of the desmoplastic tumor microenvironment (TME) of ICC has been stressed, but was insufficiently taken into account in the search for classifications of ICC adapted to clinical trial design. We investigated the heterogeneous tumor stroma composition and built a TME-based classification of ICC tumors, which detects potentially targetable ICC subtypes. METHODS:We established the bulk gene expression profiles of 78 ICCs. Epithelial and stromal compartments of 23 ICCs were laser microdissected. We quantified 14 gene-expression signatures of the TME and those of 3 functional indicators (liver activity, inflammation, immune resistance). The cell population abundances were quantified using the Microenvironment Cell Populations (MCP)-counter package and compared with immunohistochemistry. We performed an unsupervised TME-based classification of 198 ICCs (training set) and 368 ICCs (validation set). We determined immune response and signaling features of the different immune subtypes by functional annotations. RESULTS:We showed that a set of 198 ICCs could be classified into 4 TME-based subtypes related to distinct immune escape mechanisms and patient outcomes. The validity of these immune subtypes was confirmed over an independent set of 368 ICCs and by immunohistochemical analysis of 64 ICC tissue samples. About 45% of ICCs displayed an immune desert phenotype. The other subtypes differed in the nature (lymphoid, myeloid, mesenchymal) and abundance of tumor infiltrating cells. The inflamed subtype (11%) presented a massive T-lymphocyte infiltration, an activation of inflammatory and immune checkpoint pathways, and was associated with the longest patient survival. CONCLUSION:We revealed the existence of an inflamed ICC subtype, which is potentially treatable with checkpoint blockade immunotherapy.
Project description:The tumor microenvironment (TME) chiefly consists of tumor cells and tumor-infiltrating immune cells admixed with the stromal component. A recent clinical trial has shown that the tumor immune cell infiltration (ICI) is correlated with the sensitivity to immunotherapy and the head and neck squamous cell carcinoma (HNSC) prognosis. However, to date, the immune infiltrative landscape of HNSC has not yet been elucidated. Herein, we proposed two computational algorithms to unravel the ICI landscape of 1,029 HNSC patients. Three ICI patterns were defined, and the ICI scores were determined by using principal-component analysis. A high ICI score was characterized by an increased tumor mutation burden (TMB) and the immune-activating signaling pathways. Activation of transforming growth factor-? (TGF-?) and WNT signaling pathways were observed in low ICI score subtypes, indicating T cell suppression, and may be responsible for poor prognosis. Two immunotherapy cohorts confirmed patients with higher ICI scores demonstrated significant therapeutic advantages and clinical benefits. This study demonstrated that the ICI scores serve as an effective prognostic biomarker and predictive indicator for immunotherapy. Evaluating the ICI patterns of a larger cohort of samples will extend our understanding of TME, and it may provide directions to the current research investigations on immunotherapeutic strategies for HNSC. Graphical Abstract Understanding the tumor-immune microenvironment is critical for improving the efficacy of current immunotherapies. Zhang et al. comprehensively evaluated the cellular, molecular, and genetic factors associated with immune cell infiltration patterns. These have important implications for how tumors respond to immunotherapies and may guide more effective immunotherapy strategies.
Project description:The biological and functional heterogeneity between tumors-both across and within cancer types-poses a challenge for immunotherapy. To understand the factors underlying tumor immune heterogeneity and immunotherapy sensitivity, we established a library of congenic tumor cell clones from an autochthonous mouse model of pancreatic adenocarcinoma. These clones generated tumors that recapitulated T cell-inflamed and non-T-cell-inflamed tumor microenvironments upon implantation in immunocompetent mice, with distinct patterns of infiltration by immune cell subsets. Co-injecting tumor cell clones revealed the non-T-cell-inflamed phenotype is dominant and that both quantitative and qualitative features of intratumoral CD8+ T cells determine response to therapy. Transcriptomic and epigenetic analyses revealed tumor-cell-intrinsic production of the chemokine CXCL1 as a determinant of the non-T-cell-inflamed microenvironment, and ablation of CXCL1 promoted T cell infiltration and sensitivity to a combination immunotherapy regimen. Thus, tumor cell-intrinsic factors shape the tumor immune microenvironment and influence the outcome of immunotherapy.
Project description:Single-agent immunotherapy has achieved limited clinical benefit to date in patients with pancreatic ductal adenocarcinoma (PDAC). This may be a result of the presence of a uniquely immunosuppressive tumor microenvironment (TME). Critical obstacles to immunotherapy in PDAC tumors include a high number of tumor-associated immunosuppressive cells and a uniquely desmoplastic stroma that functions as a barrier to T cell infiltration. We identified hyperactivated focal adhesion kinase (FAK) activity in neoplastic PDAC cells as an important regulator of the fibrotic and immunosuppressive TME. We found that FAK activity was elevated in human PDAC tissues and correlated with high levels of fibrosis and poor CD8(+) cytotoxic T cell infiltration. Single-agent FAK inhibition using the selective FAK inhibitor VS-4718 substantially limited tumor progression, resulting in a doubling of survival in the p48-Cre;LSL-Kras(G12D);Trp53(flox/+) (KPC) mouse model of human PDAC. This delay in tumor progression was associated with markedly reduced tumor fibrosis and decreased numbers of tumor-infiltrating immunosuppressive cells. We also found that FAK inhibition rendered the previously unresponsive KPC mouse model responsive to T cell immunotherapy and PD-1 antagonists. These data suggest that FAK inhibition increases immune surveillance by overcoming the fibrotic and immunosuppressive PDAC TME and renders tumors responsive to immunotherapy.
Project description:The tumor microenvironment (TME) constitutes a complex milieu of cells and cytokines that maintain equilibrium between tumor progression and prognosis. However, comprehensive analysis of the TME and its clinical significance in head and neck squamous cell carcinoma (HNSCC) remains to be unreported. In this study, based on large-scale RNA sequencing data pertaining to single nucleotide variants (SNVs) and copy number variations (CNVs) in HNSCC patients from The Cancer Genome Atlas database, we analysed subpopulations of infiltrating immune cells and evaluated the role of TME infiltration pattern (TME score) in assessing immunotherapy outcome. TME signature genes involved in several inflammation and immunity signalling pathways were observed in the TME score subtype, which were considered immunosuppressive and potentially responsible for significantly worse prognosis. In comparison with SNV- and CNV-mediated tumor mutation burden, TME score can significantly differentiate between high- and low-risk HNSCC and predict immunotherapy outcome. Our data provide clarity on the comprehensive landscape of interactions between clinical characteristics of HNSCC and tumor-infiltrating immune cells. TME score seems to be a useful biomarker that can predict immunotherapy outcome in HNSCC patients.
Project description:Macrophages are a major component of the tumor microenvironment (TME) of most tumors. They are characterized by a high degree of functional plasticity which enable these cells to both promote and eliminate established tumors. Under the influence of immunosuppressive TME, tumor infiltrating iNOS+ and CD11b+ M-1 effector macrophages get polarized towards tumor associated macrophages (TAM) which are tropic to variety of tumors. Increased infiltration and density of TAM is associated with tumor progression and poor prognosis in the plethora of tumors due to their angiogenetic and tissue re-modelling nature. Importantly, TAMs are also responsible for developing endothelium anergy, a major physical barrier for majority of cancer directed immune/chemotherapies. Therefore, functional retuning/re-educating TAM to M-1 phenotypic macrophages is paramount for effective immunotherapy against established tumors. In this review, we discuss and provide comprehensive update on TAM-targeted approaches for enhancing immunity against various solid tumors.
Project description:Although immune checkpoint blockade (ICB) therapy has revolutionized cancer treatment, many patients do not respond or develop resistance to ICB. N6 -methylation of adenosine (m6A) in RNA regulates many pathophysiological processes. Here, we show that deletion of the m6A demethylase Alkbh5 sensitized tumors to cancer immunotherapy. Alkbh5 has effects on m6A density and splicing events in tumors during ICB. Alkbh5 modulates Mct4/Slc16a3 expression and lactate content of the tumor microenvironment and the composition of tumor-infiltrating Treg and myeloid-derived suppressor cells. Importantly, a small-molecule Alkbh5 inhibitor enhanced the efficacy of cancer immunotherapy. Notably, the ALKBH5 gene mutation and expression status of melanoma patients correlate with their response to immunotherapy. Our results suggest that m6A demethylases in tumor cells contribute to the efficacy of immunotherapy and identify ALKBH5 as a potential therapeutic target to enhance immunotherapy outcome in melanoma, colorectal, and potentially other cancers.
Project description:Immunotherapeutics represent highly promising agents with the potential to improve patient outcomes in a variety of cancer types. Unfortunately, single-agent immunotherapy has achieved limited clinical benefit to date in patients suffering from pancreatic ductal adenocarcinoma (PDAC). This may be due to the presence of a uniquely immunosuppressive tumor microenvironment (TME) present in PDACs, which creates a barrier to effective immune surveillance. Critical obstacles to immunotherapy in PDAC tumors include the dense desmoplastic stroma that acts as a barrier to T-cell infiltration and the high numbers of tumor-associated immunosuppressive cells. We have identified hyperactivated focal adhesion kinase (FAK) activity in neoplastic PDAC cells as a significant regulator of the fibrotic and immunosuppressive TME. We found that FAK activity was elevated in human PDAC tissues and correlates with high levels of fibrosis and poor CD8+ cytotoxic T-cell infiltration. Single-agent FAK inhibition (VS-4718) dramatically limited tumor progression, resulting in a doubling of survival in the p48-Cre/LSL-KrasG12D/p53Flox/+ (KPC) mouse model of human PDAC. This alteration in tumor progression was associated with dramatically reduced tumor fibrosis, decreased numbers of tumor-infiltrating immature myeloid cells and immunosuppressive macrophages. We postulated that these desirable effects of FAK inhibition on the TME might render PDAC tumors more sensitive to immunotherapy. Accordingly, we found that VS-4718 rendered the previously unresponsive KPC mouse model responsive to anti-PD1 and anti-CTLA4 antagonists leading to a nearly tripling of survival times. These data suggest that FAK inhibition increases immune surveillance by overcoming the fibrotic and immunosuppressive PDAC TME thus rendering tumors more responsive to immunotherapy. We treated KP orthotopic tumor-bearing mice with vehicle and FAK inhibitor (FAKi) for 14 days, then extracted total RNA from tumor tissues.