Project description:We used CRISPR/Cas9 genome editing to inactivate KRAS in pancreatic cancer cells and isolated cell populations that still produce tumors in mice. We show that the malignant phenotype of KRAS knockout cells is stable. However, KRAS deficient cancer cells fail to avoid detection and elimination by the host immune system, indicating that a key aspect of tumor maintenance by oncogenic KRAS is to promote immune evasion. Our study uncovers changes both in cancer cells and stromal immunoreactive cells attributable to KRAS expression. Complementation studies indicate that BRAF, AKT and MYC are causative drivers of KRAS-mediated immune suppression. These results show that combination treatments that both target KRAS signaling and boost antitumor immunity will be an effective strategy to treat PDAC.
Project description:Intratumoral microbiota can impact the development and progression of many types of cancer, including gastric cancer (GC). A better understanding of the precise mechanisms by which microbiota support GC could lead to improved therapeutic approaches. Here, we investigated the effect of intratumoral microbiota on the tumor immune microenvironment (TIME) during GC malignant progression. Analysis of human GC tissues with 16S rRNA amplicon sequencing revealed that Fusobacterium nucleatum (F. nucleatum) was significantly enriched in GC tissues with lymph node metastasis and correlated with a poor prognosis. F. nucleatum infection spontaneously induced chronic gastritis and promoted gastric mucosa dysplasia in mice. Furthermore, GC cells infected with F. nucleatum showed accelerated growth in immunocompetent mice compared to immunodeficient mice. Single-cell RNA sequencing uncovered that F. nucleatum recruited tumor-associated neutrophils (TANs) to reshape the tumor immune microenvironment. Mechanistically, F. nucleatum invaded GC cells and activated IL-17/NF-κB/RelB signaling, inducing TAN recruitment. F. nucleatum also stimulated TAN differentiation into the pro-tumoral subtype and subsequent promotion of PD-L1 expression, further facilitating GC immune evasion while also enhancing the efficacy of anti-PD-L1 antibody therapy. Together, this data uncovers mechanisms by which F. nucleatum affects GC immune evasion and immunotherapy efficacy, providing insights for developing effective treatment strategies.
Project description:We reveal a negative association between Human Papillomavirus (HPV)-encoded circular RNA, circE7, and the infiltration of CD8+ T cells in head and neck squamous cell carcinoma (HNSCC). Both in vitro and in vivo experiments demonstrate that circE7 suppresses the function and activity of T cells by downregulating the transcription of LGALS9, which encodes the galectin-9 protein. The molecular mechanism involves circE7 binding to acetyl-CoA carboxylase 1 (ACC1), promoting its dephosphorylation and thereby activating ACC1. Activated ACC1 reduces H3K27 acetylation at the LGALS9 gene promoter, leading to decreased galectin-9 expression. Notably, galectin-9 interacts with immune checkpoint molecules TIM-3 and PD-1, inhibiting the secretion of cytotoxic cytokines by T cells and promoting T cell apoptosis. Here, we demonstrate a mechanism by which HPV promotes immune evasion in HNSCC through a circE7-driven epigenetic modification, and propose a potential immunotherapy strategy for HNSCC that involves the combined use of anti-PD-1 and anti-TIM-3 inhibitors.
Project description:Accumulated genetic mutations or copy number alterations are frequently observed in esophageal squamous cell carcinoma (ESCC) patients. However, it is still elusive which gene is the driver to initiate ESCC. We identified key genetic determinants for ESCC development using CRISPR/Cas9-based multiple genes KO mouse esophageal organoid model. Trp53, Cdkn2a, and Notch1 triple KO (PCN) organoid showed the phenotypes of ESCC. These triple genes KO served for cell proliferation through building multiple root cell clusters and remodeling the immune landscape beneficial for tumorigenesis by Ccl2-Ccr2 mediated intercellular interactions. Ccl2-releasing PCN tumors were surrounded by exhausted T cells and M2 macrophages leading to immune evasion. The PCN-type tumor was observed in more than 30% of ESCC patients who express high levels of B2M, CCL2, and NF-kB. Our study unveiled genetic determinants for ESCC development crucial for cell-autonomous growth as well as non-cell autonomous interactions with immune cells.
Project description:Accumulated genetic mutations or copy number alterations are frequently observed in esophageal squamous cell carcinoma (ESCC) patients. However, it is still elusive which gene is the driver to initiate ESCC. We identified key genetic determinants for ESCC development using CRISPR/Cas9-based multiple genes KO mouse esophageal organoid model. Trp53, Cdkn2a, and Notch1 triple KO (PCN) organoid showed the phenotypes of ESCC. These triple genes KO served for cell proliferation through building multiple root cell clusters and remodeling the immune landscape beneficial for tumorigenesis by Ccl2-Ccr2 mediated intercellular interactions. Ccl2-releasing PCN tumors were surrounded by exhausted T cells and M2 macrophages leading to immune evasion. The PCN-type tumor was observed in more than 30% of ESCC patients who express high levels of B2M, CCL2, and NF-kB. Our study unveiled genetic determinants for ESCC development crucial for cell-autonomous growth as well as non-cell autonomous interactions with immune cells.