DNA copy amplification and overexpression of SLC12A7 in adrenocortical carcinoma

BACKGROUND: Overexpression of Solute carrier family 12 member 7 (SLC12A7) promotes tumor aggressiveness in various cancers. Previous studies have identified the 5p15.33 region, containing the SLC12A7 locus, frequently amplified in adrenocortical carcinoma (ACC). Copy number amplifications (CNA) may alter gene expression and occur frequently in ACC. However, SLC12A7 amplifications or expression levels have not been studied in ACC. METHODS: Fifty five cases of clinically well-characterized ACCs were recruited for this study. Whole-exome sequencing (WES) was used to predict CNAs in 19 samples. CNA analysis was performed on an expanded cohort of 26 samples using TaqMan Copy Number Assays. SLC12A7 mRNA expression was analyzed in 32 samples using real-time quantitative PCR and protein expression was assessed by immunohistochemistry. SLC12A7 CNAs and expression patterns were evaluated for correlation with patient and tumor characteristics. RESULTS: WES and Taqman Copy Number Assays demonstrated SLC12A7 amplifications in 68.4% and 65.4% of ACCs tested, respectively. SLC12A7 expression levels were increased in ACCs compared to normal adrenal tissue (p