Abstract 121: Analysis and comparison of somatic copy number alterations in gastric cardia adenocarcinoma and gastric non-cardia adenocarcinoma

Abstract

Abstract Gastric adenocarcinoma is one of the most common cancer type worldwide. Anatomically it may raise from the cardia or non-cardia part of the stomach and previous studies have shown differential susceptibilities loci and prognosis between gastric cardia adenocarcinoma (GCA) and gastric non-cardia adenocarcinoma (GNCA). To better understand the genomic alterations that drive gastric adenocarcinoma and to investigate the differences of genetic aberration between GCA and GNCA, we analyzed somatic copy-number aberrations in 205 gastric adenocarcinomas resected samples, including 114 GCAs and 91 GNCAs using Illumina Human OmniZhongHua BeadChips. We identified 49 significantly recurrent focal alterations in gastric adenocarcinoma. In addition to those previously reported in stomach cancer, several novel focal changes were also observed, including gain of 11p11.2, 6q23.3, 12p11.1, 5p15.33 and loss of 8p11.22, 9p22.2, 18q22.1, 15q21.2, 17q23.3. A few known or potential oncogenes such as TERT, MYB, and IRS2, were included in the focal amplified regions that were not reported in gastric cancer before. Also, a few potential tumor suppressors were seen in these focal loss regions, including DOK6, BRIP1 and NDST4. Especially, HDC, a gene involved in gastric acid secretory, was harbored in the newly identified focal loss region, 15q21.2. Three focal changes, loss of 20p12.1 (containing MACROD2), 6q26 (containing PARK2), and gain of 11p11.2 (containing CRY2), were identified to correlate to the post-surgery overall survival, which may deserve to be further investigated as the potential prognosis markers. Comparison of somatic copy number alternation patterns revealed that in chromosome arm level, 16p and 5q had distinct copy number status between GCA and GNCA samples. The frequencies of three novel focal changes were significantly different between GCA and GNCA. Furthermore, KRAS amplification, a well characterized gastric adenocarcinoma prognosis marker was associated with worse clinical outcome in GNCA, but not in GCA. Taken together, these results provided novel candidate oncogenes or tumor suppressors for gastric adenocarcinoma and different features in structural alterations between GCA and GNCA, which potentially inform novel opportunities for targeted therapeutic interventions. Citation Format: Manjiao Liu, Zhen Liu, Jian Bai, Hong Cai, Yang Ke, Changqing Zeng. Analysis and comparison of somatic copy number alterations in gastric cardia adenocarcinoma and gastric non-cardia adenocarcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 121.