乳腺癌中线粒体DNA拷贝量变化的意义

Significance of alterations of mitochondrial DNA copy number in breast carcinoma

目的通过分析mtDNA拷贝量在乳腺癌组织和癌旁正常组织中的变化，探讨其在乳腺癌发生和发展中的作用。方法采用PCR反应分别扩增20例乳腺浸润性导管癌组织和相对应的20例癌旁正常组织的mtDNAD．100p两个高突变区HV1和HV2，并以核基因组G．actin作为定量标准物，经过聚丙烯酰胺凝胶电泳法（PAGE）并利用Gel-ProExpress图像分析系统进行核酸定量分析，比较mtDNA拷贝量在癌组织和癌旁组织间的差异。结果在乳腺癌组织中HV1和HV2的条带的吸光度均较癌旁正常组织弱，其中HVl在两者比较中有统计学差异（P〈0．05）；HV2在两者比较中有明显统计学差异（P〈0．01）；统计学分析发现，HV1和HV2呈明显正相关（P〈0．01），且mtDNA的拷贝量与年龄、肿瘤大小均无统计学意义，而与淋巴结转移和肿瘤分期有统计学意义（均为P〈0．05）。结论乳腺浸润性导管癌组织mtDNA拷贝量减少，与乳腺癌的发生和发展有密切关系，并可能成为一种新的乳腺癌标志物。

Objective To explore the effect in human breast cancer occurring by analyzing the difference of mtDNA copy number in breast cancers and paracancerous tissues. Methods Polymerase chain reaction（PCR）was applied to detect the HV1 and HV2 of mtDNA D-Loop in 20 cases invasive ductual breast cancer tissues and 20 cases peritumoral tissues, meantime β-actin was served as a quantitative standard marker, it compared the difference between breast cancer and paracancerous tissues by polyacrylamide gel electrophoresis（PAGE） and analyzing nucleic acid in the Gel-Pro Express system. Results The bands of HV1 and HV2 in breast cancer tissues was weaker than that in peritumoral tissues. There was difference between two groups by HV1 （ P 〈 0.05） ; There was difference between two groups by HV2 （P 〈 0.01）. It was detected that the HV1 and HV2 were positively correlated by statistics analyzing （ P 〈 0.01 ）. There was no statistic relationship between the difference of mtDNA copy number and age and diameter, but the mtDNA copy number in lymph node metastasis group was higher than that of no lymph node metastasis group, there was difference between two groups （ P 〈 0.05）. The mtDNA copy number in phase I of TNM stage was higher than that of phase Ⅱ and Ⅲ , and there was difference between phase I and phase Ill （ P 〈 0.05）, there was difference between phase I and phase Ⅲ （ P 〈 0.05）. Conclusion The mtDNA number is descended in invasive ductual breast cancer, and it is correlated to the breast cancer occurring. The mtDNA number might be a new breast cancer marker.