Gene expression profile at single cell level of 4T1 WT and Mga KO tumors derived on BALB/c mice
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ABSTRACT: Immune evasion is critical for tumor initiation and progression, as well as determining the efficacy of immunotherapies. Through iterative in vivo CRISPR screens within seven syngeneic tumor models, we not only identified the core immune evasion pathways and context-dependent ones across cancer types but also provided a high-confidence valuable dataset for understanding tumor intrinsic immunomodulators and discovering novel anti-cancer therapeutic targets. With a focus on triple-negative breast cancer (TNBC), we found that Mga knock-out significantly enhances anti-tumor immunity and inhibits the tumor growth of TNBC model. Transcriptomics and single cell-RNA (sc-RNA) seq analyses revealed Mga function through, at least partially, repression of MHC-II genes and related immune responses. Consistently, we observed that low MGA expression in breast cancer patients correlates with a favorable prognosis, particularly in those with active interferon-g signaling. Our findings provide new insights into tumor immune escape and pave the way for further exploration of MGA inhibition for clinical benefits in triple-negative breast cancer.
Project description:Immune evasion is not only critical for tumor initiation and progression, but also determines the efficacy of immunotherapies. Through iterative in vivo CRISPR screens with seven syngeneic tumor models, we identified core and context-dependent immune evasion pathways across cancer types. We also provided a high-confidence valuable dataset for the understanding of tumor intrinsic immunomodulators and the discovery of novel anti-cancer therapeutic targets. With a focus on triple-negative breast cancer (TNBC), we found that Mga knock-out significantly enhances anti-tumor immunity and inhibits tumor growth. Transcriptomics and single-cell RNA sequencing analyses revealed that Mga functions through, at least partially, repression of MHC-II genes and related immune responses. Consistently, we observed that low MGA expression in breast cancer patients correlates with a favorable prognosis, particularly in those with active interferon-g signaling. Our findings provide new insights into tumor immune escape and pave the way for further exploration of MGA inhibition for clinical benefits in triple-negative breast cancer.
Project description:The transcriptional regulator Mga of Streptococcus pyogenes (the group A streptococcus, GAS) is known to directly activate several virulence genes important for colonization and immune evasion during exponential growth. Transcriptome analysis comparing two mga-1 serotypes (M1 SF370, M6 JRS4) and one mga-2 serotype (M4 GA40634) against their isogenic mga-inactivated strains uncovered a broader Mga regulon profile containing both activated and repressed genes with predicted functions primarily related to the uptake and metabolism of sugars. Although the divergent M1 and M4 Mga profiles were similar in size and content, the M6 JRS4 strain was clearly distinct, even from other M6 strains. Real-time RT-PCR and northern blot analysis validated our microarray results and confirmed that established core Mga regulon genes directly activated by Mga (emm, scpA, sof, fba) exhibited the highest activation levels across all strains tested. A novel ORF (Spy2036) encoding a cytosolic hypothetical protein was highly activated in all three serotypes and was called gene regulated by Mga or grm. Mga was shown to bind directly to Pgrm, which overlaps the Mga-regulated Psof in OF+ strains, suggesting that grm is part of the core Mga regulon and is able to activate two divergently transcribed genes from a single site in a class II background. Both class and serotype specific Mga-regulated genes, such as speB, were apparent. In fact, Mga activated speB as long as it was expressed in the wild type strain, although direct binding of Mga to the PspeB promoter could not be demonstrated. Thus, Mga is able to both directly and indirectly regulate genes shown to be important for virulence and the metabolic homeostasis of GAS. Keywords: Wild-type vs Mga-
Project description:The transcriptional regulator Mga of Streptococcus pyogenes (the group A streptococcus, GAS) is known to directly activate several virulence genes important for colonization and immune evasion during exponential growth. Transcriptome analysis comparing two mga-1 serotypes (M1 SF370, M6 JRS4) and one mga-2 serotype (M4 GA40634) against their isogenic mga-inactivated strains uncovered a broader Mga regulon profile containing both activated and repressed genes with predicted functions primarily related to the uptake and metabolism of sugars. Although the divergent M1 and M4 Mga profiles were similar in size and content, the M6 JRS4 strain was clearly distinct, even from other M6 strains. Real-time RT-PCR and northern blot analysis validated our microarray results and confirmed that established core Mga regulon genes directly activated by Mga (emm, scpA, sof, fba) exhibited the highest activation levels across all strains tested. A novel ORF (Spy2036) encoding a cytosolic hypothetical protein was highly activated in all three serotypes and was called gene regulated by Mga or grm. Mga was shown to bind directly to Pgrm, which overlaps the Mga-regulated Psof in OF+ strains, suggesting that grm is part of the core Mga regulon and is able to activate two divergently transcribed genes from a single site in a class II background. Both class and serotype specific Mga-regulated genes, such as speB, were apparent. In fact, Mga activated speB as long as it was expressed in the wild type strain, although direct binding of Mga to the PspeB promoter could not be demonstrated. Thus, Mga is able to both directly and indirectly regulate genes shown to be important for virulence and the metabolic homeostasis of GAS. Keywords: Wild-type vs Mga-
Project description:The transcriptional regulator Mga of Streptococcus pyogenes (the group A streptococcus, GAS) is known to directly activate several virulence genes important for colonization and immune evasion during exponential growth. Transcriptome analysis comparing two mga-1 serotypes (M1 SF370, M6 JRS4) and one mga-2 serotype (M4 GA40634) against their isogenic mga-inactivated strains uncovered a broader Mga regulon profile containing both activated and repressed genes with predicted functions primarily related to the uptake and metabolism of sugars. Although the divergent M1 and M4 Mga profiles were similar in size and content, the M6 JRS4 strain was clearly distinct, even from other M6 strains. Real-time RT-PCR and northern blot analysis validated our microarray results and confirmed that established core Mga regulon genes directly activated by Mga (emm, scpA, sof, fba) exhibited the highest activation levels across all strains tested. A novel ORF (Spy2036) encoding a cytosolic hypothetical protein was highly activated in all three serotypes and was called gene regulated by Mga or grm. Mga was shown to bind directly to Pgrm, which overlaps the Mga-regulated Psof in OF+ strains, suggesting that grm is part of the core Mga regulon and is able to activate two divergently transcribed genes from a single site in a class II background. Both class and serotype specific Mga-regulated genes, such as speB, were apparent. In fact, Mga activated speB as long as it was expressed in the wild type strain, although direct binding of Mga to the PspeB promoter could not be demonstrated. Thus, Mga is able to both directly and indirectly regulate genes shown to be important for virulence and the metabolic homeostasis of GAS. Keywords: Wild-type vs Mga-
Project description:Triple-negative breast cancer represents approximately 15–20% of all reported breast cancer cases, and is characterized by a shorter survival time and higher mortality rates compared to other breast cancer sub-types. Tumor microenvironment (TME) refers to the internal and external environment of tumor tissue. Increasing evidence indicates that a tumor’s microenvironment is tightly associated with the immunological surveillance and defense during the development of breast cancer. Although oncology studies employing digital dissection methodologies have provided some insight on the biological features of TME, the development of methods to investigate the cellular composition of the tumor microenvironment remain an important research priority. In this study, we extracted whole transcriptome from 30 Triple-negative breast cancer (TNBC) patients and then used bioinformatics approaches to characterize cell type content in tumor tissue compared with para-cancerous tissue. We identified 4 types of enriched immune cells and 6 types of downregulated immune cells in the tumor tissue samples. After comprehensive bioinformatics analyses, we developed an ‘immune infiltration score’ (IIS) to quantitatively model immune cell infiltration in TNBC. To demonstrate the utility of the IIS, we used 2 independent datasets for validation. We found that patients with a higher IIS showing a longer progression-free survival time and significantly better prognosis than those with a lower IIS value. In sum, we explored the immune infiltration landscape in 30 TNBC patients and provided a novel and reliable biomarker IIS to evaluate the progression-free survival and prognosis in the TNBC patients.
Project description:Triple-negative breast cancer (TNBC) is an aggressive malignant disease that is responsible for approximately 15% of breast cancers. The standard of care relies on surgery and chemotherapy but the prognosis is poor and there is an urgent need for new therapeutic strategies. Recent in silico studies have revealed an inverse correlation between recurrence-free survival and the level of cyclin- dependent kinase 8 (CDK8) in breast cancer patients. CDK8 is known to have a role in natural killer (NK) cell cytotoxicity, but its function in TNBC progression and immune cell recognition or escape has not been investigated. We have used a murine model of orthotopic breast cancer to study the tumor-intrinsic role of CDK8 in TNBC. Knockdown of CDK8 in TNBC cells impairs tumor regrowth upon surgical removal and prevents metastasis. In the absence of CDK8, the epithelial-to-mesenchymal transition (EMT) is impaired and immune-mediated tumor-cell clearance is facilitated. CDK8 drives EMT in TNBC cells in a kinase-independent manner. In vivo experiments have confirmed that CDK8 is a crucial regulator of NK-cell-mediated immune evasion in TNBC. The studies also show that CDK8 is involved in regulating the checkpoint inhibitor programmed death-ligand 1 (PD-L1). The CDK8–PD-L1 axis is found in mouse and human TNBC cells, underlining the importance of CDK8-driven immune cell evasion in these highly aggressive breast cancer cells. Our data link CDK8 to PD-L1 expression and provide a rationale for investigating the possibility of CDK8-directed therapy for TNBC.
Project description:Breast cancer is genetically and clinically heterogeneous. Triple negative cancer (TNBC) is a subtype of breast cancer usually associated with poor outcome and lack of benefit from target therapy. A pathway analysis in a microarray study was performed using TNBC compared with non-triple negative breast cancer (non-TNBC). Overexpression of several Wnt pathway genes, such as frizzled homolog 7 (FZD7), Low density lipoprotein receptor-related protein 6 (LRP6) and transcription factor 7 (TCF7) has been observed in TNBC. Focus was given to the Wnt pathway receptor, FZD7. To validate its function, inhibition of FZD7 using FZD7shRNA was carried out. Notably decreased cell proliferation, suppressed invasiveness and colony formation in triple negative MDA-MB-231 and BT-20 cells were observed. Mechanism study indicated that these effects occurred through silencing the canonical Wnt signaling pathway, as evidenced by loss of nuclear accumulation of ï?¢-catenin and decreased transcriptional activity of TCF7. In vivo study revealed that FZD7shRNA significantly suppressed the tumor formation in xenotransplation mice due to decrease cell proliferation. Our finding suggests that FZD7 involved canonical Wnt signaling pathway is essential for tumorigenesis of TNBC. Thus, FZD7 may be a biomarker and a potential therapeutic target for triple negative breast cancer. 14 pretreatment non-triple negative breast tumors compare with 5 triple negative breast tumor.
Project description:Triple negative breast cancer (TNBC) lacks targeted therapy options. TNBC is enriched in breast cancer stem cells (BCSCs), which play a key role in metastasis, chemoresistance, relapse and mortality. γδ T cells hold great potential in immunotherapy against cancer, and might be an alternative to target TNBC. γδ T cells are commonly observed to infiltrate solid tumors and have an extensive repertoire of tumor sensing, recognizing stress-induced molecules and phosphoantigens (pAgs) on transformed cells. We show that patient derived triple negative BCSCs are efficiently recognized and killed by ex vivo expanded γδ T cells from healthy donors. Orthotopically xenografted BCSCs, however, were refractory to γδ T cell immunotherapy. Mechanistically, we unraveled concerted differentiation and immune escape: xenografted BCSCs lost stemness, expression of γδ T cell ligands, adhesion molecules and pAgs, thereby evading immune recognition by γδ T cells. Indeed, neither pro-migratory engineered γδ T cells, nor anti-PD 1 checkpoint blockade significantly prolonged overall survival of tumor-bearing mice. BCSC immune escape was independent of the immune pressure exerted by the γδ T cells, and could be pharmacologically reverted by Zoledronate or IFN-α treatment. These results pave the way for novel combinatorial immunotherapies for TNBC.
Project description:The MYC oncogene is frequently amplified in triple negative breast cancer (TNBC). Here, we show that MYC suppression induces immune-related hallmark gene set signatures and tumor infiltrating T cells in MYC-hyperactivated TNBCs. Mechanistically, MYC repressed stimulator of interferon genes (STING) expression via direct binding to the STING enhancer region, resulting in downregulation of the T cell chemokines CCL5, CXCL10 and CXCL11. In primary and metastatic TNBC cohorts, tumors with high MYC expression or activity exhibited low STING expression. Using a CRISPR-mediated enhancer perturbation approach, we demonstrated that MYC-driven immune evasion is mediated by STING repression. STING repression induced resistance to PD-L1 blockade in mouse models of TNBC. Finally, a small molecule inhibitor of MYC combined with PD-L1 blockade elicited a durable response in immune-cold TNBC with high MYC levels, suggesting a strategy to restore PD-L1 inhibitor sensitivity in MYC-overexpressing TNBC.