Gene expression profile of esophageal cancer in North East India by cDNA microarray analysis

To identify alterations in genes and molecular functional pathways in esophageal cancer in a high incidence region of India where there is a widespread use of tobacco and betel quid with fermented areca nuts.

Total RNA was isolated from tumor and matched normal tissue of 16 patients with esophageal squamous cell carcinoma. Pooled tumor tissue RNA was labeled with Cy3-dUTP and pooled normal tissue RNA was labeled with Cy5-dUTP by direct labeling method. The labeled probes were hybridized with human 10K cDNA chip and expression profiles were analyzed by Genespring GX V 7.3 (Silicon Genetics).

Nine hundred twenty three genes were differentially expressed. Of these, 611 genes were upregulated and 312 genes were downregulated. Using stringent criteria (P < or = 0.05 and > or = 1.5 fold change), 127 differentially expressed genes (87 upregulated and 40 downregulated) were identified in tumor tissue. On the basis of Gene Ontology, four different molecular functional pathways (MAPK pathway, G-protein coupled receptor family, ion transport activity, and serine or threonine kinase activity) were most significantly upregulated and six different molecular functional pathways (structural constituent of ribosome, endopeptidase inhibitor activity, structural constituent of cytoskeleton, antioxidant activity, acyl group transferase activity, eukaryotic translation elongation factor activity) were most significantly downregulated.

Several genes that showed alterations in our study have also been reported from a high incidence area of esophageal cancer in China. This indicates that molecular profiles of esophageal cancer in these two different geographic locations are highly consistent.