ARID1A deficiency promotes mutability and potentiates therapeutic antitumor immunity unleashed by immune checkpoint...

Area of Science:

• Oncology
• Cancer Genomics
• Molecular Biology

Background:

• ARID1A (AT-rich interaction domain 1A) is frequently inactivated in various cancers, presenting a challenge for targeted therapy.
• Understanding the functional consequences of ARID1A loss is crucial for identifying therapeutic vulnerabilities in ARID1A-mutant tumors.

Purpose of the Study:

• To investigate the molecular mechanisms underlying ARID1A deficiency in cancer.
• To identify potential therapeutic strategies targeting ARID1A-mutant cancers.

Main Methods:

• Proteomic screening to identify ARID1A interacting proteins.
• Assays to assess mismatch repair (MMR) function and mutagenesis.
• Analysis of genomic data for ARID1A mutation correlations.
• In vivo studies using syngeneic mouse models of ARID1A-deficient ovarian cancer.
• Evaluation of anti-PD-L1 antibody efficacy in ARID1A-deficient tumors.

Main Results:

• ARID1A interacts with MSH2 and promotes its recruitment to chromatin, enhancing DNA mismatch repair (MMR).
• ARID1A inactivation compromises MMR, leading to increased mutagenesis, a mutator phenotype, and microsatellite instability.
• ARID1A deficiency correlates with a C>T mutation pattern and elevated mutation load across multiple cancer types.
• ARID1A-deficient ovarian tumors exhibit increased tumor-infiltrating lymphocytes and PD-L1 expression.
• Anti-PD-L1 therapy effectively reduced tumor burden and improved survival in mice with ARID1A-deficient tumors.

Conclusions:

• ARID1A deficiency impairs MMR, contributing to a mutator phenotype in cancer.
• ARID1A loss may sensitize tumors to immune checkpoint blockade therapy, such as anti-PD-L1 treatment.