Association of ATM and ARID1A in gastric carcinoma

The ataxia telangiectasia mutated (ATM) gene is involved in the repair of double-stranded DNA breaks and a component of the DNA damage repair pathway. Tumors with mutations or low expression of both ARID1A and ATM exhibit increased numbers of tumor-infiltrating lymphocytes and a favorable prognosis. However, the relationship between ATM and ARID1A in gastric carcinoma (GC) is unclear.

We used the mRNA expression data from the Asian Cancer Research Group to construct tissue microarrays (N = 249). Next-generation sequencing (NGS) databases of Samsung Medical Center (SMC) (N = 813) were used to compare genetic alterations. Tissue microarrays were used for ATM and ARID1A immunohistochemistry, and expressions were categorized as "low" and "high." NGS data from TCGA-STAD (N = 431) were used as independent cohorts for genetic alterations validation.

In GCs, 32.1 % (80/249) of the cases showed low ATM protein expression (ATM^low) and 20.9 % (52/249) showed low ARID1A expression (ARID1A^low). ATM^low was significantly associated with older age (P <.01), gross type of tumor (P =.02), histology (P <. 01), lower incidence of perineural invasion (P =.04), lower disease stage (P <.01), microsatellite instability-high (P <.01), and ARID1A^low (P <.01). Furthermore, GCs in the SMC NGS database showed that ATM mutations were significantly correlated with ARID1A mutations (P <.01), and this finding remained significant in TCGA-STAD validation cohort (P <.01).

ATM^low in GCs shows a characteristic clinicopathological feature that correlates strongly with ARID1A^low. ATM mutation was also associated with ARID1A mutations, highlighting the interactions between ATM and ARID1A in GC and suggesting a potential therapeutic target.