Array comparative genomic hybridization, expression array, and protein analysis of critical regions on chromosome arms 1q, 7q, and 8p in adenocarcinomas of the gastroesophageal junction

Abstract

Survival rates of adenocarcinomas of the gastroesophageal junction (GEJ) are low, because these tumors are generally in an advanced stage by the time they are detected. Chromosomal regions 1q32, 7q21, and 8p22 display critical alterations in GEJ cancers; however, the genes underlying alterations in these genomic areas are largely unknown. To delineate overexpressed genes, we performed array comparative genomic hybridization (aCGH) and mRNA expression analysis of 15 GEJ adenocarcinoma samples using a fine-tiling cDNA array covering chromosome segments 1q31.3∼q41 (193.9–215.8 Mb: 21.9 Mb), 7q11.23∼q22.1 (72.3–103.0 Mb: 30.7 Mb), and 8p23.1∼p21.3 (11.1–20.7 Mb: 9.6 Mb). Based on a mRNA overexpression criterion, 11 genes were selected: ELF3 and SLC45A3 on 1q; CLDN12, CDK6, SMURF1, ARPC1B, ZKSCAN1, MCM7, and COPS6 on 7q; and FDFT1 and CTSB on 8p. The protein expression levels were subsequently determined by immunohistochemical analysis of the cancer samples. There was a significant correlation between genomic amplification, mRNA, and protein expression or overexpression for CDK6, a cell cycle regulator on 7q21.2 (92.1 Mb; P < 0.01); other genes showed less stringent associations. In conclusion, using a straightforward approach we constructed a targeted gene profile for GEJ adenocarcinomas.