Epigenetic identification of ADAMTS18 as a novel 16q23.1 tumor suppressor frequently silenced in esophageal nasopharyngeal and multiple other carcinomas

摘要

Tumor Suppressor genes (TSGs) often locate at chromosomal regions with frequent deletions in tumors. Loss of 16q23 occurs frequently in multiple tumors, indicating the presence of critical TSGs at this locus, such as the well-studied WWOX. Herein we found that ADAMTS18, located next to WWOX, was significantly downregulated in multiple carcinoma cell lines. No deletion of ADAMTS18 was detected with multiplex differential DNA-PCR or high resolution 1-Mb array-based CGH analysis. Instead, methylation of the ADAMTS18 promoter CpG Island was frequently detected with methylation-specific PCR and bisulfite genome sequencing in multiple carcinoma cell lines and primary carcinomas, but not in any non-tumor cell line and normal epithelial tissue. Both pharmacological and genetic demethylation dramatically induced ADAMTS18 expression, indicating that CpG methylation directly contributes to the tumor-specific silencing of ADAMTS18. Ectopic ADAMTS18 expression leads to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells lacking the expression. Thus, through functional epigenetics, we identified ADAMTS18 as a novel functional tumor suppressor, being frequently inactivated epigenetically in multiple carcinomas.