[Suppression of RASSF1A gene on human esophageal carcinoma cells: experiments in vitro and in vivo].

OBJECTIVE

To investigate the effect of Ras association domain family 1A (RASSF1A) gene, a new tumor suppressor gene (TSG), on tumorigenesis of human esophageal carcinoma cells.

METHODS

pcDNA3.1 (+)-RASSF1A, a plasmid containing RASSF1A gene, and the blank plasmid pcDNA3.1 (+) were transfected into human esophageal carcinoma cells of the line EC9706. The expression of RASSF 1A protein was examined by Western blotting. The changes of cell cycle of stably-transfected cells were determined by flow cytometry (FCM), and the cellular proliferation was analyzed by MTT assay. Fifteen nude mice were randomly divided into 3 groups to be inoculated subcutaneously with EC9706 cells transfected with pcDNA3.1 (+)-RASSF1A, EC9706 cells transfected with pcDNA3.1 (+), and untransfected EC9706 cells respectively. Other 5 nude mice were used as controls. Four weeks later, the mice were killed to take out the carcinoma tissues. FCM was used to analyze the cell cycle.

RESULTS

Western blotting showed that RASSF1A protein was expressed highly in the stably transfected cells. The cell viability and growing speed were decreased obviously in the cells expressing of RASSF1A (both P < 0.01); FCM showed that the proportion of cells at the G(1) phase of the EC9706 cells expressing RASSF1A was significantly higher than those in the blank plasmid group and untransfected group (both P < 0.01). The size of the EC9706 cells obtained from the nude mice inoculated with the EC9706 cells transfected with pcDNA3.1 (+)-RASSF1A was significantly smaller than those of the pcDNA3.1 (+) group and blank plasmid group (both P < 0.05).

CONCLUSION

Expression of exogenous RASSF1A inhibits the progression of human esophageal carcinoma cells in vitro and in vivo. As a tumor suppressor gene, it plays an important role in origination, progression and metastasis of esophageal carcinoma.