Previous studies of comparative genomic hybridization showed the common genomic amplification of chromosome 5p regions in esophageal squamous cell carcinoma (ESCC) cell lines and patient cases of Hong Kong Chinese origin. This observation implies that the genes located in chromosome 5p regions may play crucial roles in molecular carcinogenesis of ESCC. Our previous studies on ESCC reported the overexpression and tumorigenic properties of a novel gene JS-1 located in chromosome 5p15.2. In the present study, a novel gene located in 5p15.1, named as JK-1, was further characterized for its roles in the molecular carcinogenesis in ESCC. Thirteen cell lines and 30 surgical specimens of ESCC were studied for the overexpression of JK-1 using semi-quantitative RT-PCR analysis. The transforming capacity of overexpression of JK-1 was also investigated by transfecting NIH-3T3 cells with the expression vector containing the coding sequence of JK-1 to detect the colony formation in soft agar. Overexpression of JK-1 was shown in 9/13 (69%) of ESCC cell lines when compared with the expression level in an immortalized non-tumor esophageal epithelial cell line. JK-1 overexpression was also detected in 9/30 (30%) of ESCC patient cases when compared with the corresponding non-tumor esophageal epithelial tissues. Overexpression of JK-1 in NIH-3T3 cells also caused colony formation in soft agar in day 10. Our overall results thus provide the first evidence that the overexpression and transforming capacity of JK-1 in normal cells may play a critical role in the molecular pathogenesis of ESCC.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]