The Expression Of ERCC1 And DNA-PKcs In NSCLC And The Relation To Prognosis

IntroductionThe development of lung cancer involves in many factors and genes.The accumulation of gene mutation aroused as a result of impaired repairmen of DNA damage that are caused by endogenous and exogenous carcinogen,are thought to be an important cause of lung cancer.DNA repair system is necessary for human living,which play an important role in sustaining genomic stability and antagonizing cancer.The abnormal number of DNA repair gene are related to cancer incidence and prognosis.Low expression or gene mutation of DNA repair genes often accompanied by increased instability and even malignant phenotype of tumor,overexpression of these genes contributed to chemotherapy and radiotherapy resistance.Exsicion repair cross-complement group1(ERCC1)and DNA-dependent protein kinase catalytic subunit(DNA-PKcs),as the key factor in the repairmen of DNA damage,are related to oncogenesis,development and prognosis of tumor as many studies indicated.The two proteins were both related to the resistance of cisplatin which was the major chemotherapy drug for lung cancer,and the radiotherapy sensitivity of tumor.So far,the mechanism of ERCC1 and DNA-PKcs was not clear.There was no report on the combination determination of them in cancer tissues.The aim of this study is to investigated the expression and clinical significance of ERCC1 and DNA-PKcs in patients with NSCLC,and analyze the relationship between the expression of ERCC1 and DNA-PKcs with prognosis.Methods 1.Specimens Paraffin-embedded specimens from 116 patients with lung cancer and 12 normal lung tissues adjacent to the cancer tissues were collected from the first affiliated hospital of China medical university,with which microarray was constructed.All the cases included 85 males and 31 females,with median age 57.5 years old.None of them underwent chemotherapy and immunotherapy before operation. The deadline of follow-up was September 2005.2.Materials The monoclonal mouse anti-human antibodies against ERCC1 and DNA-PKcs at a 1:100 dilution were purchased from Neomarkers,USA.SP immunohistochemical kits and DAB substrate solution were purchased from Foochow Maixin Biotechnology Corporation.3.Methods The expression of ERCC1 and DNA-PKcs were detected with SP immunohistochemsitry.All slides were treated with 0.01%citric acid buffer(PH=6.0) to recover the antigen activity in autoclave.4.Assessment Outcome definition of ERCC1 and DNA-PKcs were stained palm yellow particle in nucleus.Tumor tissues were counted the positive cells of 5 random images at high magnification(×400),positive cells＞10%as positive,≤10%as negative.5.statistical analysis Statistical methods x~2 test,Spearman rank correlation test and Kaplan-Meier survival analysis were performed by SPSS software version 13.0Results1.Expression of ERCC1 and DNA-PKcs in patients with NSCLCThe positive rate of ERCC1 and DNA-PKcs expression in NSCLC was 40.5%and 75%,respectively.There were no significant difference between ERCC1 expresson in tumor tissue and normal tissue(P=0.106).The expression of DNA-PKcs in tumor tissue was significantly higher than that in normal lung tissue adjacent to the tumor tissues (x~2=17.467,P=0.000). 2.The relationship between expression of ERCC1 and DNA-PKcs and clinicopathologic parameters in patients with NSCLCThe expression of ERCC1 was closely related to differentiation(x~2= 5.160,P=0.023),T stage(x~2=7.068,P=0.008)and clinic stage(x~2=4.033,P=0.045),but not to age,sex,smoke,lymph node metastasis and tumors histological type.The expression of DNA-PKcs was not related to all clinical characteristics(P＞0.05)3.The relation between ERCC1 and DNA-PKcsThere was positive correlation between the expression of ERCC1 and DNA-PKcs(P=0.003).4.The relationship between expression of ERCC1 and DNA-PKcs and survival in patients with NSCLCThe patients with high expression of ERCC1 seemed to have better prongosis.The five-year survival rate of NSCLC patients with ERCC1 positive expression were higher than those with ERCC1 negative expression(P=0.014).The expression of DNA-PKcs was not related to prognosis of NSCLC patients(P＞0.05).Multivariate analysis showed that clinic stage rather than ERCC1 and DNA-PKcs was the independent predictor for the prognosis(P=0.000).Conclusion1.The expression of ERCC1 may be associated with tumor differentiation,clinic stage and better survival,which maybe useful to predict prognosis.2.The positive expression level of DNA-PKcs in non-small cell lung cancer tissues was higher than that in normal tissues.3.There was positive correlation between the expression of ERCC1 and DNA-PKcs...