Cancer cell intrinsic SSBP4 enables tumor immune evasion by promoting cholesterol biosynthesis [ATAC-Seq]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE328718 | GEO | 2026/04/30
REPOSITORIES: GEO
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Project description:The immunosuppressive tumor microenvironment (TME) contributes to resistance against checkpoint inhibitors. However, the precise factors that shape the immune contexture of the TME remain elusive. Here, we report that Single-Stranded DNA Binding Protein 4 (SSBP4), a previously uncharacterized protein, suppresses intratumoral T-cell activation by promoting excessive cholesteryl ester production in tumor cells. Overexpression of SSBP4 in tumor cells decreased T-cell infiltration and accelerated tumor growth in murine syngeneic tumor models. Conversely, genetic ablation of SSBP4 in tumor cells enhanced T-cell infiltration and inhibited tumor growth in a CD8+ T cell–-dependent manner. Mechanistically, SSBP4 upregulated cholesterol synthesis genes, leading to increased production of cholesterol and cholesteryl esters in tumor cells, which directly suppressed CD8+ T-cell activation and function. Furthermore, SSBP4 abrogation significantly improved the efficacy of anti-PD-1 treatment. Thus, in this study, we have identified SSBP4 as a cancer cell–intrinsic regulator of cholesterol metabolism that contributes to tumor immune evasion.
2026-04-30 | GSE328971 | GEO
Project description:The immunosuppressive tumor microenvironment (TME) contributes to resistance against checkpoint inhibitors. However, the precise factors that shape the immune contexture of the TME remain elusive. Here, we report that Single-Stranded DNA Binding Protein 4 (SSBP4), a previously uncharacterized protein, suppresses intratumoral T-cell activation by promoting excessive cholesteryl ester production in tumor cells. Overexpression of SSBP4 in tumor cells decreased T-cell infiltration and accelerated tumor growth in murine syngeneic tumor models. Conversely, genetic ablation of SSBP4 in tumor cells enhanced T-cell infiltration and inhibited tumor growth in a CD8+ T cell–-dependent manner. Mechanistically, SSBP4 upregulated cholesterol synthesis genes, leading to increased production of cholesterol and cholesteryl esters in tumor cells, which directly suppressed CD8+ T-cell activation and function. Furthermore, SSBP4 abrogation significantly improved the efficacy of anti-PD-1 treatment. Thus, in this study, we have identified SSBP4 as a cancer cell–intrinsic regulator of cholesterol metabolism that contributes to tumor immune evasion.
2026-04-30 | GSE328719 | GEO
Project description:The immunosuppressive tumor microenvironment (TME) contributes to resistance against checkpoint inhibitors. However, the precise factors that shape the immune contexture of the TME remain elusive. Here, we report that Single-Stranded DNA Binding Protein 4 (SSBP4), a previously uncharacterized protein, suppresses intratumoral T-cell activation by promoting excessive cholesteryl ester production in tumor cells. Overexpression of SSBP4 in tumor cells decreased T-cell infiltration and accelerated tumor growth in murine syngeneic tumor models. Conversely, genetic ablation of SSBP4 in tumor cells enhanced T-cell infiltration and inhibited tumor growth in a CD8+ T cell–-dependent manner. Mechanistically, SSBP4 upregulated cholesterol synthesis genes, leading to increased production of cholesterol and cholesteryl esters in tumor cells, which directly suppressed CD8+ T-cell activation and function. Furthermore, SSBP4 abrogation significantly improved the efficacy of anti-PD-1 treatment. Thus, in this study, we have identified SSBP4 as a cancer cell–intrinsic regulator of cholesterol metabolism that contributes to tumor immune evasion. Immune-related gene expression was quantified using the Nanostring Mouse PanCancer Immune Profiling panel. Total RNA was isolated from the C57BL/6 SSBP4-wildtype or knockout B16F10 tumors on Day 15 post tumor inoculation. RNA was hybridized, scanned on a Nanostring Digital Analyzer, and raw RCC files were generated. Raw count data were processed and normalized in nSolver or ROSALIND software for downstream immune transcriptome profiling.
2026-04-30 | GSE329266 | GEO
Project description:The immunosuppressive tumor microenvironment (TME) contributes to resistance against checkpoint inhibitors. However, the precise factors that shape the immune contexture of the TME remain elusive. Here, we report that Single-Stranded DNA Binding Protein 4 (SSBP4), a previously uncharacterized protein, suppresses intratumoral T-cell activation by promoting excessive cholesteryl ester production in tumor cells. Overexpression of SSBP4 in tumor cells decreased T-cell infiltration and accelerated tumor growth in murine syngeneic tumor models. Conversely, genetic ablation of SSBP4 in tumor cells enhanced T-cell infiltration and inhibited tumor growth in a CD8+ T cell–-dependent manner. Mechanistically, SSBP4 upregulated cholesterol synthesis genes, leading to increased production of cholesterol and cholesteryl esters in tumor cells, which directly suppressed CD8+ T-cell activation and function. Furthermore, SSBP4 abrogation significantly improved the efficacy of anti-PD-1 treatment. Thus, in this study, we have identified SSBP4 as a cancer cell–intrinsic regulator of cholesterol metabolism that contributes to tumor immune evasion. Immune-related gene expression was quantified using the Nanostring nCounter Myeloid Innate Immunity Panel. Total RNA was isolated from splenic CD8 T cells of C57BL/6 mice, where were cultured with conditioned media from SSBP4-wildtype or knockout B16F10 tumor cells. RNA was extracted from CD8 T cells, hybridized, scanned on a Nanostring Digital Analyzer, and raw RCC files were generated. Raw count data were processed and normalized in nSolver software for downstream immune transcriptome profiling.
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Project description:Non-alcoholic fatty liver disease (NAFLD) is an emerging risk factor of hepatocellular carcinoma (HCC). However, the mechanism and target therapy on NAFLD-HCC are still unclear. Here, we identify that the N6-methyladenosine (m6A) methyltransferase METTL3 promotes NAFLD-HCC. Hepatocyte-specific Mettl3 knockin exacerbated NAFLD-HCC formation while Mettl3 knockout exerted an opposite effect in mice. Single-cell RNA-seq revealed that METTL3 suppressed antitumor immune response by reducing infiltration of Gzmb+ and IFN-γ+ CD8+ T-cell, thereby facilitating immune escape. Mechanistically, METTL3 mediates SCAP mRNA m6A to promote its translation, leading to the activation of cholesterol biosynthesis. This enhanced secretion of cholesterol and cholesteryl esters, lipotoxins that impaired CD8+ T cell function in tumor microenvironment. Targeting of METTL3 by sgRNA, nanoparticle-siRNA, or pharmacological inhibitor (STM2457) in combination with anti-PD1 synergized to reinvigorate cytotoxic CD8+ T cells and mediate tumor regression. Together, METTL3 is a therapeutic target in NAFLD-HCC, especially in conjunction with immune checkpoint blockade (ICB) therapy.
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Project description:Non-alcoholic fatty liver disease (NAFLD) is an emerging risk factor of hepatocellular carcinoma (HCC). However, the mechanism and target therapy on NAFLD-HCC are still unclear. Here, we identify that the N6-methyladenosine (m6A) methyltransferase METTL3 promotes NAFLD-HCC. Hepatocyte-specific Mettl3 knockin exacerbated NAFLD-HCC formation while Mettl3 knockout exerted an opposite effect in mice. Single-cell RNA-seq revealed that METTL3 suppressed antitumor immune response by reducing infiltration of Gzmb+ and IFN-γ+ CD8+ T-cell, thereby facilitating immune escape. Mechanistically, METTL3 mediates SCAP mRNA m6A to promote its translation, leading to the activation of cholesterol biosynthesis. This enhanced secretion of cholesterol and cholesteryl esters, lipotoxins that impaired CD8+ T cell function in tumor microenvironment. Targeting of METTL3 by sgRNA, nanoparticle-siRNA, or pharmacological inhibitor (STM2457) in combination with anti-PD1 synergized to reinvigorate cytotoxic CD8+ T cells and mediate tumor regression. Together, METTL3 is a therapeutic target in NAFLD-HCC, especially in conjunction with immune checkpoint blockade (ICB) therapy.
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