CANCER V-ATPase EXPRESSION SIGNATURES: A DISTINCTIVE BALANCE OF SUBUNIT C ISOFORMS IN ESOPHAGEAL CARCINOMA

Abstract

V-ATPases are hetero-oligomeric enzymes consisting of 14 subunits and playing key roles in ion homeostasis and signaling. Differential expressions of these proton pumps have been implicated in carcinogenesis and metastasis. To elucidate putative molecular signatures underlying these phenomena, we evaluated the V-ATPase genes expression in Esophageal Squamous Cell Carcinoma (ESCC) using gene expression microarray data and extended the analysis to other cancers the Oncomine database. Among all differentially expressed genes, those encoding the V-ATPase C isoforms exhibited striking expression patterns validated by qRT-PCR in paired ESCC samples and respective normal surrounding tissues. Structural modeling of C2a isoform uncovered motifs for oncogenic kinases in an additional peptide stretch, and an actin-biding domain downstream to this sequence. This study reveals multi-cancer molecular signatures in the V-ATPase structure and establishes that the expression ratios of its subunits/isoforms could form a conformational code that controls the pump regulation and interactions related to tumorigenic events.