Significance Of Change Of Mitochondrial DNA Copy Number And MRNA Expression In Breast Carcinoma

Background: Mitochondrial DNA (mtDNA) is the only germ out ofnuclear DNA; It easily becomes attacked target by carcinogen,because oflacking histone protecting and effectual repairing system. It is known thatmtDNA is related to many diseases and tumours. mtDNA Cyt-b can codeone subunit of oxidative phosphorylation respire chain complexâ…¢,evolvement speed moderate and stabilation. In recent years, lots ofspecial mtDNA mutations in gene stabilize region about disease werereported, which offered reliable thereunder for diseases diagnose andresearch. Vascular endothelial growth factor (VEGF) plays a crucial rolein the process of growth and metastasis of breast cancer; it has turnedinto the research focus in the tumour.Objective: 1) To detect the copy numbers of mtDNA in breastcarcinoma; 2) To detect the expression of the mtDNA Cyt-b and VEGF inbreast carcinoma; 3) To detect the proteid expression of the VEGF andthe microvessel density (MVD); To investigate the role and relationshipof the factors in breast cancer.Methods:1) The HV₁ and HV₂ of the mitochondrial D-loop region from 20 cases breast cancer tissues and 20 cases paracancerous tissueswere amplified by PCR; meantimeβ-actin was served as a quantitativestandard marker,followed by polyacrylamide gel electrophoresis (PAGE)and silver staining, in which the difference of mtDNA copy number wascompared between breast cancer and paracancerous tissues; 2) ThemtDNA Cyt-b and VEGF mRNA from 19 eases breast cancer tissues and19 cases paracancerous tissues were amplified by RT-PCR; meantimeβ-actin was served as a quantitative standard marker, and the differenceof mRNA expression was compared between breast cancer andparacancerous tissues; 3) The expression levels of VEGF and CD34protein were assessed in 42 cases of breast cancer tissues and 30 casesparacancerous tissues with S-P immunohistochemical method, and thedifference was compared between breast cancer and paracanceroustissues.Results: 1) There existed difference in HV₁ and HV₂ (standardizedwithβ-actin) between breast cancer and paracancerous tissues (P＜0.05and P＜0.01); 2) There existed difference in mtDNA Cyt-b and VEGFmRNA expression between breast cancer and paracancerous tissues(P＜0.01), and mtDNA Cyt-b and VEGF mRNA expression was positivecorrelation (P＜0.01). 3) The expression rate of VEGF protein was 73.8ï¼…(31/42) in the breast cancer tissues, and 10ï¼…(3/30)in the paracanceroustissues which had significant differrnce between two groups (P＜0.01). The expression of VEGF protein and VEGF mRNA was positivecorrelation (P＜0.01). The MVD and the VEGF protein were positivecorrelation (P＜0.01).Conclusions: 1) The mtDNA copy number in breast cancer is higuerthan in paracancerous tissues, which can be used to early diagnosebreast cancer. 2) The expression of mtDNA Cyt-b mRNA in breastcancer is higher than in paracancerous tissues, which may be a newbreast tumor marker 3) The expression of VEGF mRNA in breast canceris higher than in paracancerous tissues. 4) There is positive correlationbetween mtDNA Cyt-b and VEGF mRNA expression in breast carcinoma.5) There is positive correlation between VEGF protein and VEGF mRNAexpression in breast carcinoma. 6) There is positive correlation betweenMVD and VEGF protein and VEGF mRNA expression in breastcarcinoma,which can be one prognostic impersonality index, and also be atarget of therapy with blood vessel inhibitor.