Profiling of differentially expressed cancer-related genes in esophageal squamous cell carcinoma (ESCC) using human cancer cDNA arrays: Overexpression of oncogene MET correlates with tumor differentiation in ESCC

Purpose: To examine the global gene expression of cancer-related genes in e sophageal squamous cell carcinoma (ESCC) through the use of Atlas Human Can cer Array membranes printed with 588 well-characterized human genes involve d in cancer and tumor biology. Experimental Design: Two human ESCC cell lines (HKESC-1 and HKESC-2) and on e morphologically normal esophageal epithelium tissue specimen from the pat ient of which the RKESC-2 was derived were screened in parallel using cDNA expression arrays. The array results were additionally validated using semi quantitative PCR. The overexpression of oncogene MET was studied more exten sively for its protein expression by immunohistochemistry in the two ESCC c ell lines and their corresponding primary tissues and 61 primary ESCC resec ted specimens. Sixteen of these 61 ESCC cases also had available the corres ponding morphologically normal esophageal epithelium tissues and were also analyzed for MET expression. The clinicopathological features associated wi th overexpression of the MET gene were also correlated. Results: The results of cDNA arrays showed that 13 cancer-related genes wer e up-regulated greater than or equal to2-fold (CDC25B, cyclin D1, PCNA, MET , Jagged 2, Integrin alpha3, Integrin alpha6, Integrin beta4, Caveolin-2, C aveolin-1, MMP13, MMP14, and BIGH3) and 5 genes were down-regulated greater than or equal to2-fold (CK4, Bad, IGFBP2, CSPCP, and IL-1RA) in both ESCC cell lines at the mRNA level. Semiquantitative RT-PCR analysis of 9 of thes e differentially expressed genes, including the MET gene, gave results cons istent with cDNA array findings. The immunostaining results of the expressi on of MET gene showed that MET was overexpressed in both ESCC cell lines an d their corresponding primary tumors at the protein level, validating the c DNA arrays findings. The results of the clinical specimens showed that the MET gene was overexpressed in ESCC compared with normal esophageal epitheli um in 56 of 61 cases (92%). Moreover, the overexpression of MET protein was more often seen in well/moderately differentiated than in poorly different iated ESCC. Conclusions: Multiple cancer-related genes are differentially expressed in ESCC, the oncogene MET is overexpressed in ESCC compared with normal esopha geal epithelium, and its protein overexpression correlates with tumor diffe rentiation in ESCC.