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Genetic screens reveal new targetable vulnerabilities in BAP1-deficient Mesothelioma

ABSTRACT: More than half of malignant mesothelioma patients show alterations in the BAP1 tumour suppressor gene. Being a member of the Polycomb repressive deubiquitinating (PR-DUB) complex, BAP1 loss results in an altered epigenome which may create new vulnerabilities that remain largely unknown. Here we performed a CRISPR/Cas9-kinome screen in mesothelioma cells that identified two kinases in the Mevalonate/Cholesterol biosynthesis pathway. Furthermore, our analysis of chromatin, expression and genetic perturbation data in mesothelioma cells suggests a dependency on Polycomb repressive complex 2 (PRC2) mediated silencing. Pharmacological inhibition of PRC2 elevates the expression of cholesterol biosynthesis genes only in BAP1-deficient mesothelioma, thereby sensitizing these cells to the combined targeting of PRC2 and the mevalonate pathway. Finally, by subjecting autochthonous Bap1-deficient mesothelioma mice or xenografts to mevalonate pathway inhibition (Zoledronic Acid) and PRC2 inhibition (Tazemetostat), we demonstrate a potent anti-tumour effect, suggesting a targeted combination therapy for Bap1-deficient mesothelioma

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE222376 | GEO | 2023/01/12

REPOSITORIES: GEO

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Project description:BRCA-1 Associated Protein (BAP1) is a deubiquitinating enzyme that acts as a tumour suppressor. Inactivating mutations in the BAP1 gene have been identified in many cancers including cholangiocarcinoma, hepatocellular carcinoma, mesothelioma, uveal melanoma and renal cell carcinoma. Current standard therapeutic approaches for BAP1-deficient tumours are not particularly promising, contributing to poor overall survival and disease-free survival rates. Here, we found BAP1 to mediate the turnover of the key proteins in the DNA nucleotide excision repair (NER) pathway, and therefore promotes DNA repair. Importantly, we demonstrate that the loss of functional BAP1 sensitise tumour cells to LSD1 inhibitor, SP2509, in vitro and in vivo, through further impairment of NER efficiency. When used in combination with PARP1 inhibitor, Olaparib, we show that a synergistic drug combination response is achieved. Overall, our study identifies a drug combination approach that has the potential to be exploited clinically to target BAP1 deficient tumours.

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2019-01-28 | PXD011808 | Pride

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2011-05-19 | E-GEOD-29383 | biostudies-arrayexpress

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2011-05-19 | E-GEOD-29354 | biostudies-arrayexpress

Mesothelioma tumor aCGH profiles

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2011-09-25 | E-GEOD-29902 | biostudies-arrayexpress

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Two distinct functional axes of positive feedback-enforced PRC2 recruitment in mouse embryonic stem cells

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