[Studies of the suppressive effect of cDNA RA538 on three human cancer cell lines].

As previously reported, transfer of RA538 into parental esophageal cancer EC8712 cell line induced its terminal differentiation and apoptosis. To further study the biological effects of this cDNA, an expression plasmid containing an insert of the putative coding fragment (about 0.3kb) of RA538 and neo resistance gene was constructed (designated pRA538-0.3-neo) and transferred into three different human cancer cell lines: EC8712, HL60 and GLC, a cell line derived from an adenocarcinoma of the lung. After selection in G418-containing culture media, the growth rate, 3H-thymidine incorporation rate, cell morphology, colony-formation in soft-agar, and heterotransplantation into nude mice of the surviving cell populations were tested. In situ hybridization verified the uptake and expression of the 0.3kb fragment of RA538 in these G418 resistant cell populations. Significant reduction in growth rate and suppression of malignant phenotype were observed in all these cells in comparison with their parental cancer cell lines.