Bin Zhang

Druggable genome CRISPR screening identifies the KEAP1/NRF2 axis as a mediator of PD-L1 expression

Cancer cells rapidly induce PD-L1 expression in response to inflammatory cytokines such as IFNγ from cytotoxic T cells. Increased surface PD-L1 is a primary mechanism of cancer cells evading cytotoxic T-cell-mediated immune clearance. Identifying how cancer cells increase PD-L1 expression may yield clinically relevant immune checkpoint regulators. However, the key regulators and molecular mechanisms mediating rapid PD-L1 induction are yet to be understood entirely. To identify targetable mechanisms controlling cytokine-induced PD-L1 expression, we performed functional CRISPR gene KO screening with a custom-designed sgRNA library that targets "druggable" genes. We performed the screening in 6 different cancer lines: 3 ovarian (OVCAR4, CaOV3, and SKOV3) and three pancreatic cancer (MiaPaca2, ASPC1 and KP4) cell lines. The screening recovered the known regulators of PD-L1 expression and uncovered several novel regulators of PD-L1 that control its expression in all cell lines or in a cancer-type-specific fashion. For example, while genetic or pharmacological depletion of CSNK1A1 results in reduced PD-L1 expression in ovarian cancer cells, CDK1 depletion modulates PD-L1 in pancreatic cancer cell lines. Significantly, we discovered that KEAP1 depletion or pharmacological inhibition diminishes PD-L1 in all cell lines tested (n = 6). Mechanistically, KEAP1 depletion-mediated reduced PD-L1 is due to transcriptional repression of the PD-L1 gene by NRF2 activation. As such, depletion of NRF2 restores PD-L1 expression, while its overexpression leads to diminished PD-L1 expression. Supporting this, pharmacological NRF2 activation resulted in significant antitumor immunity with increased cytotoxic effector T cell infiltration and reduced exhausted T cells, resulting in smaller xenografted tumors. These findings establish the KEAP1/NRF2 axis as a novel and potentially druggable mechanism of IFNγ-meditated PD-L1 expression in cancer cells.

Multi‐omics‐based analysis of high grade serous ovarian cancer subtypes reveals distinct molecular processes linked to patient prognosis

Despite advancements in treatment, high‐grade serous ovarian cancer (HGSOC) is still characterized by poor patient outcomes. To understand the molecular heterogeneity of this disease, which underlies the challenge in selecting optimal treatments for HGSOC patients, we have integrated genomic, transcriptomic, and epigenetic information to identify seven new HGSOC subtypes using a multiscale clustering method. These subtypes not only have significantly distinct overall survival, but also exhibit unique patterns of gene expression, microRNA expression, DNA methylation, and copy number alterations. As determined by our analysis, patients with similar clinical outcomes have distinct profiles of activated or repressed cellular processes, including cell cycle, epithelial‐to‐mesenchymal transition, immune activation, interferon response, and cilium organization. Furthermore, we performed a multiscale gene co‐expression network analysis to identify subtype‐specific key regulators and predicted optimal targeted therapies based on subtype‐specific gene expression. In summary, this study provides new insights into the cellular heterogeneity of the HGSOC genomic, epigenetic, and transcriptomic landscapes and provides a basis for future studies into precision medicine for HGSOC patients.

Elevated MYO10 Predicts Poor Prognosis and its Deletion Hampers Proliferation and Migration Potentials of Cells Through Rewiring PI3K/Akt Signaling in Cervical Cancer

MYO10, recognized as an important regulator of cytoskeleton remodeling, has been reported to be associated with tumorigenesis. However, its functional implication in cervical cancer and potential mechanism still remain to be undetermined currently. MYO10 level in cervical cancer tissues was analyzed by using data retrieved from The Cancer Genome Atlas and ONCOMINE databases. Messenger RNA and protein expression levels were determined by quantitative real-time polymerase chain reaction and Western blotting. Small-interfering RNA and overexpressing plasmid were used for MYO10 silencing and overexpression, and cell proliferation was analyzed by CCK-8. Transwell assays were performed to investigate the ability of cell migration and invasion. MYO10 was upregulated in cervical cancer tissues and cells when compared to normal controls, and survival analysis showed patients with high MYO10 expression had worse overall survival. Moreover, knockdown/overexpression of MYO10 significantly inhibited/enhanced the proliferation, invasion, and migration capabilities of cervical cells transfected with siRNAs/overexpressing plasmid. Additionally, MYO10 silencing inhibited PI3K/Akt signaling pathway by decreasing the phosphorylation status of PI3K and AKT. Data from the present study indicated that MYO10 were overexpressed in patients with cervical cancer and positively linked with poor prognosis. Experimental results suggested that MYO10 induced a significant encouraging effect in cervical cancer cell proliferation, invasion, and migration, linked with involvement of PI3K/Akt signaling. Collectively, these results emphasize a novel role for MYO10 overexpression in cervical cancer and provide a potent therapeutic strategy against cervical cancer.