Effects of recombinant MAP30 on cell proliferation and apoptosis of human colorectal carcinoma LoVo cells.

MAP30, an attractive protein isolated from bitter melon, has been previously found to have the anti-tumor and anti-HIV activities. In this study, MAP30 was cloned and expressed and the effects of the recombinant protein on cell proliferation and apoptosis of human colorectal carcinoma LoVo cells were investigated. The results showed that the proliferation of LoVo cells were significantly suppressed by MAP30 in time- and dose-dependent manners at the concentration ranging from 0.67 to 4.67 muM. The apoptotic nuclei of LoVo cells induced by MAP30 were obviously observed, and the genomic degradation was detected by single-cell gel electrophoresis (comet assay). Nuclear condensation and boundary aggregation or split, apoptotic bodies were seen by fluorescence and electron microscopy. The proportion of the periodic tumor cells was altered by MAP30. Sub-G1 curves were displayed by a flow cytometry analysis. Results of northern and western blots showed that the transcription and expression of Bax, a member of pro-apoptotic proteins, were gradually up-regulated as treated time increased. On the contrary, the transcription and expression of Bcl-2, an anti-apoptotic member, were down-regulated. These data provided powerful evidences for the first time that recombinant MAP30 can induce the apoptosis of the human colorectal carcinoma LoVo cells.