Expression Of Hrad51 Gene Protein In Benign And Malignant Lesions Of Human Mammary Tissue

Since 1990, a lot of enzymes and protein molecules related to DNA repair mechanism have been isolated and purified. By now, people have cloned many kinds of human DNA repair genes. It is believed that the defect of human DNA repair genes could lead to chromosome aberrations and the development of some human primary tumors. DNA repair gene hrad51 was first cloned in 1993. It maps to chromosome I5q15.1 and encodes a putative 339-amino acid protein-hRAD51 protein.In this study, immunohistochemical staining (with anti-hRAD51 1G8 monoclonal antibody) were used to detect hRAD51 protein expression in 25 cases of fibroadenoma, 22 cases of atypical hyperplasia, 64 cases of primary breast carcinoma and 10 cases of para-carcinoma tissues. Moreover, in the cases of breast carcinoma without chemotherapy, we also assess the correlation between the expression of hRAD51 and a spectrum of established tumor parameters. All patients had undergone operation between Jan. 1998 and Oct. 2000.The hRAD51 protein expression was found at different positive rates. The positive rates of hRAD51 in fibroadenoma, atypical hyperplasia, para-carcinoma, breast carcinoma cases without chemotherapy and with chemotherapy were 4%(l/25), 13.6%(3/22), 10%(1/10), 39.2%(20/51) and 53.8%(7/13). (P<0.05) respectively with significant difference between fibroadenoma, atypical hyperplasia and breast carcinoma cases without chemotherapy. While there was no significant difference between benign breast tissues (P>0.05).In the cases of breast carcinoma without chemotherapy, there were statistically significant relations between the expression of hRAD51 and the expression of ER ( x2=4.432, P=0.035), histological grading of tumor tissues (x2=)8.138, P=0.001), and TNM stage of patients ( x 2=7.888, P=0.019). Meanwhile, there were no statistically significant relation between the expression of HRAD51 and the expression of PR, P53, age of patients , number of metastatic lymph nodes , the types of tumor , the sizes of tumor(P>0.05).By the rank correlation according to Kendall, we found that a direct correlation between hRAD51 over-expression and tumor histological grading ( T =0.600, P=0.000), TNM stage of patients ( T =0.374, P=0.008), respectively. In addition, hRADSl over-expression inversely correlated with the estrogen-receptor status of the tumors ( =-0.337, P=0.022).From above we suggested that: A. DNA repair protein hRAD51 existed in human breast tissue, with different degree in different breast lesions, and it is over-expressed in breast carcinoma; B. In the cases of breast carcinoma, hRAD51 over-expression have a direct correlation with tumor grading and TNM stage; While inversely correlated with the ER status of the tumors; C. hRAD51 over-expression could be related to poor prognosis of breast carcinoma. A study involves a large number of cases may be necessary.