Hou Qingsong, Wu Yong Hui, Grabsch Heike, Zhu Yansong, Leong Siew Hong, Ganesan Kumaresan, Cross Debra, Tan Lay Keng, Tao Jiong, Gopalakrishnan Veena, Tang Bor Luen, Kon Oi Lian, Tan Patrick
National Cancer Centre, Department of Biochemistry, National University of Singapore, Duke-NUS Graduate Medical School, and Genome Institute of Singapore, Singapore, Singapore.
Cancer Res. 2008 Jun 15;68(12):4623-30. doi: 10.1158/0008-5472.CAN-07-5870.
Recurrent genomic amplifications and deletions are frequently observed in primary gastric cancers (GC). However, identifying specific oncogenes and tumor suppressor genes within these regions can be challenging, as they often cover tens to hundreds of genes. Here, we combined high-resolution array-based comparative genomic hybridization (aCGH) with gene expression profiling to target genes within focal high-level amplifications in GC cell lines, and identified RAB23 as an amplified and overexpressed Chr 6p11p12 gene in Hs746T cells. High RAB23 protein expression was also observed in some lines lacking RAB23 amplification, suggesting additional mechanisms for up-regulating RAB23 besides gene amplification. siRNA silencing of RAB23 significantly reduced cellular invasion and migration in Hs746T cells, whereas overexpression of RAB23 enhanced cellular invasion in AGS cells. RAB23 amplifications in primary gastric tumors were confirmed by both fluorescence in situ hybridization and genomic qPCR, and in two independent patient cohorts from Hong Kong and the United Kingdom RAB23 expression was significantly associated with diffuse-type GC (dGC) compared with intestinal-type GC (iGC). These results provide further evidence that dGC and iGC likely represent two molecularly distinct tumor types, and show that investigating focal chromosomal amplifications by combining high-resolution aCGH with expression profiling is a powerful strategy for identifying novel cancer genes in regions of recurrent chromosomal aberration.
原发性胃癌（GC）中经常观察到复发性基因组扩增和缺失。然而，在这些区域内鉴定特定的致癌基因和肿瘤抑制基因可能具有挑战性，因为它们通常涵盖数十至数百个基因。在这里，我们将基于高分辨率阵列的比较基因组杂交（aCGH）与基因表达谱分析相结合，以靶向GC细胞系中局灶性高水平扩增区域内的基因，并确定RAB23是Hs746T细胞中一个扩增且过表达的6号染色体p11p12基因。在一些缺乏RAB23扩增的细胞系中也观察到高RAB23蛋白表达，这表明除了基因扩增外，还有其他上调RAB23的机制。RAB23的siRNA沉默显著降低了Hs746T细胞的细胞侵袭和迁移能力，而RAB23的过表达增强了AGS细胞的细胞侵袭能力。通过荧光原位杂交和基因组定量PCR证实了原发性胃肿瘤中存在RAB23扩增，并且在来自香港和英国的两个独立患者队列中，与肠型GC（iGC）相比，RAB23表达与弥漫型GC（dGC）显著相关。这些结果进一步证明dGC和iGC可能代表两种分子上不同的肿瘤类型，并表明将高分辨率aCGH与表达谱分析相结合来研究局灶性染色体扩增是在复发性染色体畸变区域鉴定新型癌症基因的有力策略。
