RESUMO
AIM: To know the variations of the cytochrome b gene in cancer tissue, paracarinoma tissue and normal tissue and to inquire into the relationship between mutations of mitochondrial genome and carcinogenesis. METHODS: Cellular total DNA was extracted.The cytochrome b genes of three tissues were amplifyed with polymerase chain reaction(PCR). PCR products were analysed by DNA auto-sequencing method. RESULTS: The cytochrome b gene of cancer tissue had the C to G mutation at nt 14931, the C to G mutation at nt 15004 and the T to C mutation at nt15435,respectively. The cytochrome b gene of paracarinoma tissue had the A to C mutation at nt 15436. The cytochrome b gene of normal tissue had not mutation. CONCLUSION: Mitochondrial DNA mutations could be the endogenous factors that induce nuclear genome mutation. It could promoto carcinogenesis. The paracarinoma tissue was abnormal in DNA molecular level.