Project description:Activation of antigen presentation has been shown to contribute to improved immunotherapy outcomes. Herein, we show that inducing tumor cell ferroptosis boosts anti-tumor immunity by potentiating major histocompatibility complex II (MHC-II)- dependent antigen presentation in tumor-infiltrating macrophages. Supporting our findings with multi-omics data, we reported that ferroptotic tumor-derived all-trans retinoic acid (ATRA) is a novel regulator of MHC-II in macrophages. ATRA directly targets CD38 through transcriptional factor RARα and activates master regulator TFEB to control MHC-II expression by inducing autophagy. Clinically, a ferroptosis signature is associated with better immunotherapy response. We also innovatively develop a drug-free nano-redox lever (DFNRL) to circumvent the non-specific limitations of conventional drugs, which specifically targets and disrupts glutathione metabolism in tumor cells by accepting electrons, thereby boosting ferroptosis-mediated immune stimulation. This synergizes with anti–PD-1 immunotherapy across preclinical models. Our study answers an unidentified role for ferroptosis in modulating anti-tumor immunity and provides a clinically translatable approach to enhance immunotherapy efficacy.
Project description:While the IFN-γ-STAT1 signaling pathway is well-characterized in promoting MHC class II (MHC-II)-dependent antigen presentation within pro-inflammatory macrophages during acute infections, its functional dynamics in tumor-associated macrophages (TAMs) remain poorly understood. Here, we systematically investigated the immunomodulatory role of IFN-γ-STAT1 axis in TAMs through integrative bioinformatics and experimental validation. Transcriptomic analysis of tumor-infiltrating myeloid cells across multiple cancer cohorts revealed a strong correlation between STAT1 activation and MHC-II pathway enrichment, particularly in IFN-γ-high TAM subsets. To mechanistically dissect this relationship, we employed bone marrow-derived macrophages (BMDMs) polarized under tumor-conditioned media and subjected them to IFN-γ stimulation. Single-cell RNA sequencing demonstrated that IFN-γ triggered STAT1 nuclear translocation, upregulating MHC-II genes. Our findings establish IFN-γ-STAT1 as a master regulator of TAM immunogenicity, proposing targeted STAT1 activation as a strategy to overcome myeloid-driven immunosuppression in cancer.
Project description:There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.
Project description:There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.
Project description:There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.
Project description:There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.
Project description:Despite the importance of tumor-associated macrophages (TAMs) in modulating anti-tumor immunity, the molecular determinants of their functional phenotypes remain elusive. Through a large-scale CRISPR screen, we discovered that tumor-derived lactic acid, PGE2, and GM-CSF collaboratively shape the highly conserved but mutually exclusive TAM phenotypes: MHC-II+ and angiogenic TAMs. Mechanistically, the dichotomous nature of these two phenotypes is driven by the antagonistic interactions between lactic acid/PGE2 and GM-CSF. Lactic acid and PGE2 coordinately induce the angiogenic gene program while suppressing the GM-CSF-induced MHC-II program at chromatin level. This mechanism leads to distinct spatial distribution of TAMs, with angiogenic TAMs in lactate-rich hypoxic regions and MHC-II+ TAMs outside these areas. Furthermore, in vivo genetic perturbation of TAMs showed that shifting TAMs to an interferon responsive program, triggered by Adar inactivation, substantially potentiates anti-tumor immunity. Our findings suggest a conserved mechanism of TAM polarization and a potential approach for reprogramming TAMs in immunotherapy.
Project description:Despite the importance of tumor-associated macrophages (TAMs) in modulating anti-tumor immunity, the molecular determinants of their functional phenotypes remain elusive. Through a large-scale CRISPR screen, we discovered that tumor-derived lactic acid, PGE2, and GM-CSF collaboratively shape the highly conserved but mutually exclusive TAM phenotypes: MHC-II+ and angiogenic TAMs. Mechanistically, the dichotomous nature of these two phenotypes is driven by the antagonistic interactions between lactic acid/PGE2 and GM-CSF. Lactic acid and PGE2 coordinately induce the angiogenic gene program while suppressing the GM-CSF-induced MHC-II program at chromatin level. This mechanism leads to distinct spatial distribution of TAMs, with angiogenic TAMs in lactate-rich hypoxic regions and MHC-II+ TAMs outside these areas. Furthermore, in vivo genetic perturbation of TAMs showed that shifting TAMs to an interferon responsive program, triggered by Adar inactivation, substantially potentiates anti-tumor immunity. Our findings suggest a conserved mechanism of TAM polarization and a potential approach for reprogramming TAMs in immunotherapy.
Project description:Despite the importance of tumor-associated macrophages (TAMs) in modulating anti-tumor immunity, the molecular determinants of their functional phenotypes remain elusive. Through a large-scale CRISPR screen, we discovered that tumor-derived lactic acid, PGE2, and GM-CSF collaboratively shape the highly conserved but mutually exclusive TAM phenotypes: MHC-II+ and angiogenic TAMs. Mechanistically, the dichotomous nature of these two phenotypes is driven by the antagonistic interactions between lactic acid/PGE2 and GM-CSF. Lactic acid and PGE2 coordinately induce the angiogenic gene program while suppressing the GM-CSF-induced MHC-II program at chromatin level. This mechanism leads to distinct spatial distribution of TAMs, with angiogenic TAMs in lactate-rich hypoxic regions and MHC-II+ TAMs outside these areas. Furthermore, in vivo genetic perturbation of TAMs showed that shifting TAMs to an interferon responsive program, triggered by Adar inactivation, substantially potentiates anti-tumor immunity. Our findings suggest a conserved mechanism of TAM polarization and a potential approach for reprogramming TAMs in immunotherapy.