A two-way effect of MnSOD overexpression on proliferation of esophageal cancer cell line TE-1 and

Objective:  To  explore  the  effect  of  manganese  superoxide  dismutase  (MnSOD) overexpression on the proliferation of esophageal cancer cell line TE-1 in vivo and in vitro. Methods: TE-1 cells were transfected with a plasmid binding MnSOD cDNA, and then TE-1Mm cells (with moderate expression of MnSOD) and TE-1Mh cells (with high expression of MnSOD) were established. RT-PCR and Western blotting were used to detect the mRNA and protein expressions of target MnSOD gene in both of TE-1Mm and TE-1Mh cells, respectively. The ability of cell proliferation and apoptosis and the cell cycle distribution were examined by plate colony-forming test and flow cytometry (FCM). The xenograft tumor models in nude mice were established. The effect of MnSOD overexpression on cell proliferation was evaluated in vivo, and the expression of MnSOD protein in xenograft tumors was detected by immunohistochemistry and Western blotting. Results: TE-1 cells with different expression levels of MnSOD proteins were established by transfection with different amounts of plasmids binding MnSOD cDNA. The colony-formation rates of TE-1Mm and TE-1Mh cells were (23.0±2.7)% and (45.3±4.5)%, respectively, which were both significantly higher than those in TE-1 cells (34.7±4.2)% and TE-1n cells (33.7±4.7)%, P＜0.05. The apoptosis rate of TE-1Mm (10.6±1.0)% was significantly higher than those in TE-1 cells (34.7±4.2)% and TE-1n cells (33.7±4.7)%, and the apoptosis rate of TE-1Mh (10.6±1.0)% was significantly lower than those in TE-1 cells and TE-1n cells (P＜0.05). FCM revealed that the percentage of TE-1Mh cells was decreased in G0/G1 phase and increased in G2/M and S phases, while the percentage of TE-1Mm cells was increased in G0/G1 phase and decreased in G2/M and S phasesinduced by MnSOD overexpression. The growth of xenograft tumors was inhibited in TE-1Mm cell-implanted group, while which was improved in TE-1Mh cell-implanted group. The expressions of MnSOD protein in TE-1Mm and TE-1Mh cells were significantly higher than those in TE-1 and TE-1n cells (P＜0.05). Conclusion: MnSOD overexpression exerts a two-way effect involving inhibition or promotion on the proliferation of TE-1 cells in vivo and in vitro. DOI:10.3781/j.issn.1000-7431.2011.02.002