Genome-wide analysis of chromosomal alterations in patients with esophageal squamous cell carcinoma exposed to tobacco and betel quid from high-risk area in India

Genomic alterations such as chromosomal amplifications, deletions and loss of heterozygosity play an important role in the pathogenesis and progression of cancer. Environmental risk factors contribute to the development and progression of tumors by facilitating the loss of tumor suppressor genes and amplification of oncogenes. In this current study, Affymetrix 10K single nucleotide polymorphism (SNP) arrays were used to evaluate genomic alterations in 20 pairs of matched germ-line and tumor DNA obtained from patients with esophageal squamous cell carcinoma (ESCC) from high-risk area of India where tobacco, betel quid and alcohol use are widespread. Twenty-two amplified regions and 16 deleted regions identified across chromosomal arms were biologically relevant. The candidate genes located at amplified regions of chromosomes or low-level gain regions such as PLA2G5 (1p36-p34), COL11A1 (1p21), KCNK2 (1q41), S100A3 (1q21), ENAH (1q42.12), RGS1 (1q31), KCNH1 (1q32-q41), INSIG2 (2q14.1), FGF12 (3q28), TRIO (5p15.2), RNASEN (5p15.2), FGF10 (5p13-p12), EDN1(6p24.1-p22.3), SULF1 (8q13.2-13.3), TLR4 (9q32-q33), TNC (9q33), NTRK2 (9q22.1), CD44 (11p13), NCAM1 (11q23.1), TRIM29 (11q22-q23), PAK1 (11q13-q14) and RAB27A (15q15-q21.1), are found to be associated with cellular migration and proliferation, tumor cell metastasis and invasion, anchorage independent growth and inhibition of apoptosis. The candidate genes located at deleted regions of chromosomes, such as FBLN2 (3p25.1), WNT7A (3p25), DLC1 (8p22), LZTS1 (8p22), CDKN2A (9p21), COL4A1 (13q34), CDK8 (13q12) and DCC (18q21.3), are found to be associated with the suppression of tumor. The suggested candidate genes were mostly involved in potential signaling pathways such as focal adhesion (COL4A1), tight junction (CLDN10), MAPK signaling pathway (FGF12) and neuroactive ligand receptor interaction pathway (CCKAR). Expression of FGF12 and COL4A1 was validated by tissue microarray. These unique copy number alteration profiles should be taken into consideration when developing biomarkers for the early detection of ESCC in high-risk areas of India in association with tobacco and betel quid use.