Induction of apoptosis by TPA and VP—16 is through translocation of TR3

AIM：To investigate the role of TR3 in induction of apoptosis in gastric cancer cells.METHODS:Human gastric cancer cell line,MGC80-3,was used .Expression of TR3 mRNA and its protein was detected by Northern blot and Western blot Localization of TR3 protein was showed by imunofluorescence analysis under laser-scanning confocal microscope.Apoptotic morthology was observed by DAPL fluorescence staining,and apoptotic index was couted manong 10000 cells randomly Stable transfection assay was carried out by Lipofectamine.RESULTS:Treatment of MGC80-3 cells with TPA and VP-16 resulted in apoptosis,accompanied by the repression of Bcl-2 protein in atime-dependent manner,At the same time,TPA and VP-16 also up-regulated expression level of TR3 mRNA in MGC80-3 cells that expressed TR3 mRNA When antisense-TR3 expression vector was transfected into the cells,expression of TR3 protein was repressed.In this case,TPA and VP-16 did not induce apoptosis.In addition,TPA and VP-16-induced apotosis involved in translocation of TR3,IN MGC80-3 cells,TR3 localized concentrative in nucleus,after treatment of cells with TPA and Vp-16,TR3 translocated from nuclesu to cytosol obviously,However,When this nuclear translocaion was blocked by LMB apoptosis was not occurred in MGC80-3 cells even in the presence of TPA and VP-16.CONCLUSION:Induction of apoptosis by TPA and VP-16 is through induction of TR3 expression and translocation of TR3 from nucleus to cytosol,Which may be a novel signal pathway for TR3,and represent the new biological function of TR3 to exert its effect on apoptosis in gastric cancer cells.

Induction of apoptosis by TPA and VP-16 is through translocation of TR3

AIM: To investigate the role of TR3 in induction of apoptosis in gastric cancer cells. METHODS: Human gastric cancer cell line, MGC80-3, was used. Expression of TR3 mRNA and its protein was detected by Northern blot and Western blot. Localization of TR3 protein was showed by immunofluorescence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1000 cells randomly. Stable transfection assay was carried out by Lipofectamine. RESULTS: Treatment of MGC80-3 cells with TPA and VP-16 resulted in apoptosis, accompanied by the repression of Bcl-2 protein in a time-dependent manner. At the same time, TPA and VP-16 also up-regulated expression level of TR3 mRNA in MGC80-3 cells that expressed TR3 mRNA. When antisense-TR3 expression vector was transfected into the cells, expression of TR3 protein was repressed. In this case, TPA and VP-16 did not induce apoptosis. In addition, TPA and VP-16-induced apoptosis involved in translocation of TR3. In MGC80-3 cells, TR3 localized concentrative in nucleus, after treatment of cells with TPA and VP-16, TR3 translocated from nucleus to cytosol obviously. However, when this nuclear translocation was blocked by LMB, apoptosis was not occurred in MGC80-3 cells even in the presence of TPA and VP-16. CONCLUSION: Induction of apoptosis by TPA and VP-16 is through induction of TR3 expression and translocation of TR3 from nucleus to cytosol, which may be a novel signal pathway for TR3, and represent the new biological function of TR3 to exert its effect on apoptosis in gastric cancer cells.