AIM:To study the effects of hydrogen peroxide onmitochondrial gene expression of intestinal epithelial cells inin vitro model of hydrogen peroxide-stimulated SW-480 cells.METHODS:RNA of hydrogen peroxide-induced SW-480cells was isolated,and reverse-transcriptional polymerasechain reaction was performed to study gene expression ofATPase subunit 6,ATPase subunit 8,cytochrome c oxidasesubunit Ⅰ(COI),cytochrome coxidase subuit Ⅱ(COⅡ)andcytochrome c oxidase subunit Ⅲ(COⅢ).Mitochondria wereisolated and activities of mitochondrial cytochrome c oxidaseand ATPase were also measured simultaneously.RESULTS:Hydrogen peroxide led to differential expressionof mitochondrial genes with some genes up-regulated ordown-regulated in a dose dependent manner.Differenceswere very obvious in expressions of mitochondrial genes ofcells treated with hydrogen peroxide in a concentration of400 μmol/L or 4 mmol/L.In general,differential expressionof mitochondrial genes was characterized by up-regulationof mitochondrial genes in the concentration of 400 μmol/Land down-regulation in the concentration of 4 mmol/L.Inconsistence with changes in mitochondrial gene expressions,hydrogen peroxide resulted in decreased activities ofcytochrome c oxidase and ATPase.CONCLUSIONS:The differential expression of mitochondrialgenes encoding cytochrome c oxidase and ATPase is involvedin apoptosis of intestinal epithelial cells by affecting activitiesof cytochorme c oxidase and ATPase. AIM: To study the effects of hydrogen peroxide on mitochondrial gene expression of intestinal epithelial cells in in vitro model of hydrogen peroxide-stimulated SW-480 cells. METHODS: RNA of hydrogen peroxide-induced SW-480 cells was isolated, and reverse-transcriptional polymerase chain reaction was performed to study gene expression of ATPase subunit 6, ATPase subunit 8, cytochrome c oxidasesubunit Ⅰ (COI), cytochrome coxidase subunit Ⅲ (COⅡ) and cytochrome c oxidaseand ATPase were also measured simultaneously.RESULTS: Hydrogen peroxide led to differential expression of mitochondrial genes with some genes up-regulated ordown-regulated in a dose dependent manner. Differenceswere very significantly in expressions of mitochondrial genes of cells treated with hydrogen peroxide in a concentration of 400 μmol / L or 4 mmol /L.In general, differential expressionof mitochondrial genes was characterized by up-regulationo f mitochondrial genes in the concentration of 400 μmol / Land down-regulation in the concentration of 4 mmol / L. Inconsistence with changes in mitochondrial gene expressions, hydrogen peroxide resulted in decreased activities of cytochrome c oxidase and ATPase. CONCLUSIONS: The differential expression of mitochondrial genes encoding cytochrome c oxidase and ATPase is involved in apoptosis of intestinal epithelial cells by affecting activities of cytochorme c oxidase and ATPase.