| Department of Nutrition and Food Hygiene, The Fourth Military Medical University Xi'an 710032Zinc, an essential element for life, plays a fundamental role in expression of the genetic potential, growth and proliferation of cells. The synthesis, repair and structural integrity of nucleic acid require zinc. Recently, it has been shown that the relationship between zinc and apoptosis is very complex. Variation in dose of zinc means variation in the relationship between zinc and apoptosis. Depletion of zinc has been reported to induced apoptosis. Reports have demonstrated that addition of zinc inhibited apoptosis induced by a variety of agents. It has been also shown that excessive zinc induced apoptosis. The experiment was designed to investigate the apoptosis of rat glicorna cells by excessive or deficient zinc, to gain a preliminary insight into the mechanisms. The main contents and results of this study are as follows:1. To study the effect of excessive zinc on viability of rat glicoma cells in vitro.MTT assay was used to examine the effect of excessive zinc for 24h on the growth of rat glicoma cells. Result show that 300 u mol/L Zn2+ for 24h inhibited rat glicoma cells growth.2.TPEN is a membrane permanent chelator of divalent zinc. TPEN is generally used as a rather specific Zn2+ chelator. MTT assay was used to examine the effect of TPEN for 24h on the growth of rat glicoma cells. Result show that 5 n mol/L TPEN for 24h inhibited rat glicoma cells growth.3. Apoptosis and the molecular mechanisms of apoptosis have aroused general interest at present. The relationship between zinc and apoptosis has attracted more attention. Most studies concentrated on apoptosis induced by deficient zinc but there are comparatively fewer reports on apoptosis induced by excessive zinc. To study the effects of excessive or deficient zinc on cells apoptosis. We used agarose gel electrophoresis, light microscope, trans-electron miscroscope and flow cytometry to detect the apoptosis of rat glicoma cells growth. "DNA ladder" was shown on DNA agarose gel electrophoresis .The DNA degradation was accompanied by features apoptosis morphological changes by trans-electron miscroscope. Analysis of apoptosis by flow cytometry showed:the apoptotic cells accounting for 11.6% of excessive zinc group and 20.3% of deficient zinc group. The result indicated excessive or deficient zinc could induce apoptosis of rat glicoma cells.4. wt-p53 has been called the "guardian of the genome".wt-p53 has ability to cause cell cycle arrest or induce apoptosis to certain types of DNA damage. We used RT-PCR to observe the effects of excessive or deficient zinc on the expression of wt-p53 in rat glicoma cells. Result show that the expression of wt-p53 of rat glicoma cells increased dominantly in deficient zinc group ,but not expression in excessive zinc group. The result indicated the expression of wt-p53mRNA of rat glicoma cells was up regulated by deficient zinc and inhibited by excessive zinc. |
