| AIM: Cancer is one of diseases these influence the human health. Some reports have demonstrated that the growth and development of cancer is closely associated with cell cycle disorder. That the activation of oncogene and the inactivation of anti-oncogene both act on the cell cycle will result in proliferation quickly and apoptosis slacked. In 2001, the Nobel prize was awarded to three scientists who took advanced improvement on study of cell cycle, and this provide a new clue for establishment of new strategy on research and treatment of cancer. New research documents have showed that many environmental pollutes act on cell whether inducing mutagenesis, teratogenesis and carcinogenesis is related to cell state at the phase of cell cycle. The sensibility to kill cancer cell and apoptosis induced by many anti-cancer drugs depend on the cell cycle. So, it may become a new method that selected a propriety phase in cell cycle to use anti-cancer drugs for improvement efficacy of cancer treatment by chemotherapy and radiotherapy.A lot of studies have found that free radical, ROS can conduce cells oxidative stress, inducing lipid peroxidation and DNA breakage, affecting signal transduction and expression of correlative genes. The systems of oxidation/antioxidation were disordered. That ROS used in cultivated cell inducing cell towards cancer or differentiation or apoptosis is dose-dependent, and anti-cancer effect of many drugs isassociated with activation of ROS. Some experiments have suggested, the effect of anti-cancer drugs is associated with ROS and sensibility of anti-cancer drugs to cancer cell relied on the cell cycle. So, it has an important significance that deeply studies mechanisms of oxidative damage of cancer cell induced by ROS and that improves cancer therapy efficacy, and that investigates relationship between oxidative damage of cancer cells and cell cycle. It is necessary that establishes an ideal cancer cell synchronous model and studies oxidative stress by using this model.METHODS: Through compare among different method of cell synchronous, we selected TdR blocking assay as cell cycle-arrest drug and collected G1-phase cells, S-phase cells and G1/M-phase cells. H2O2 as exogenous ROS, HepG2 cells as study objects, the synchronous effect of cell, the sensibility and character of oxidative damage induced by ROS in distinguish phase at cell cycle had been investigated. The experiment was set up five groups, including group A: control group without using H202, group B: only using H2O2,not using TdR, group C: Gi-phase cells + H202, group D: S-phase cells + H202, group E G2/Mphase cells + H202- The oxidative stress state was induced by H2O2 in synchronous cells. The methods of pathological morphologic observation, flow cytometry and single cell gel electrophoresis.were used, and also changes of correlative biochemical index in oxidative stress injury were determined. Sensibility of oxidative damage induced by ROS in various phase in cell cycle and characteristic, and rule of oxidative damage in synchronous cancer cells were observed.RESULTS : In this experiment, the oxidative stress state in synchronous cells was induced by addition of H2O2 in cultured cells, and oxidative damage induced by ROS in synchronous cancer cells was observed. The results gained are as followings:According that the interval time between peak value in a cell proliferate period after cells were synchronized, we count that: HepG2 cell cycle is 22h, Gi-phase 15.3h,S-phase 4.6h, G2/Mphase 2.2h.This showed that the period of DNA synthesis was muchlonger than that of other phase of cell cycle, and cell division is speed. 86.3% at G1-phase cells, 66.9% at S-phase cells and 66.1% at Ga/M-phase cells in percentage distribution were collected, which showed perfect cancer cell synchronous effect. The results determined by SCGE showed that oxidative stress brought to DNA damage of synchronous cell in various phase in cell cycle, especially in S phase of HepG2 cells formed change of a "drip shape" which represents emerg... |
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