Value Of Promoter Hypermethylation Of P16、RASSF1A And FHIT Genes In The Aid Diagnosis Of Lung Cancer

BackgroundCurrently,lung cancer has become the leading canse of cancer death,its morbidity and mortality is rising, Lung cancer is now the leading cause of tumor-related death in China. The overall5-year survival rate for lung cancer is less then15%largely due to the late stage a which most patients are diagnosed.If the disease can be diagnosised in the early date and giventreatment will greatly reduce mortality of lung cancer the detection of additional prognostic parameters could be of importance to better predict the outcome of the disease.Traditional screening methods rely on imaging,sputum cytology and bronchoscopy,these diagnostic techniques did not greatly improve lung cancer mortality,Therefore,how to improve diagnosis of lung cancer is the most urgent clinical task,Excavation of valuable early screening of tumor makers become one of the problems to be solved.Molecular makers become a new method to improve the diagnosis of lung cancer,in recent years,epigenetics become a hot topic in molecular biology,which can promote tumor progress from early to the late,gene methylation is the main epigenetic modification methods.Promoter region of CpG sites detected methylation in mang malignant tumors,such as breast cancer,liver cancer,prostate cancer,including lung cancer. Molecular evidence of aberrant methylation of cytosine in promoter CpG islands causing transcriptional silencing of vital tumor suppressor genes in cancer cells has come to be recognized as an important feature of human cancer. This has been shown for a wide range of tumour suppressor genes including p16,RASSF1A and FHIT gene. In cancer, methylation of some promoter CpG islands can be an early event, and thus the detection of methylation shows great promise as a biomarker for early detection.ObjectiveTo investigate the relationship between detection of promoter methylation status of cancer suppressor genes such as the cell-cycle inhibitor gene CDKN2A (p16), Ras association domain family1A (RASSF1A) and fragile histidine triad (FHIT) genes in periphera blood in the screening and early diagnosis of lung cancer.Materials and methods:1. The choice of subjectsrthe peripheral of180patients with primary lung cancer patients were taken from Department of Respiratory of the First Affiliated Hospital of Zhengzhou University during June2011to June2012, the peripheral of180normal controls(Physical examination is normal) were taken from Department of physical examination in the same hospital during the same period.2. The detection of DNA methylation level:real-time quantitative methylaton specific PCR is used to detect the methylation level of p16,RASSF1A and FHIT gene.3. Ststistics of commonly used tumor maker between lung cancer patients and the control groups:including CEA、 CA125、 CA19-9、 NSEandCYFRA21-1.4. Ststistical anaysis runed by SPSS12.0software,Distribution type selection based on quantitative data pethods and inter-group stastical test methods,qualitative group compared with the X2test.For the skewed distribution of quantitative data,the comparison between two independent samples using the Mann-Whitny U test,Krskal Wallis test is used among comparision of groups independent samples Construction the receiver’s characteristic(receiveroperating,ROC),According to the different curve area under the ROC curve,compare the value among differenr indicators for early diagnosis of lung cancer,the difference was statistically significant is based by P<0.05. Results:1. The test results of methylation level:p16,RASSF1AandFHIT gene methylation leves is higher in lung cancer group than in the control group,the difference is statistically significant(P=0.008,P=0.038,P=0.002). There were no significant correlations between p16> RASSF1A and FHIT methylation and histological type,clinical,gender,age and history, The risk of lung cancer increased with the increased level of methylation(OR1.597,1.551,1.763respectively)2. When the imdex is tested independently,Compare the methylated gene of P16,RASSF1A and FHIT and commonly used tumor marker CA125,CA19-9, CEA,NSE and CYFRA21-1,CEA is the most valuable marker for lung cancer diagnosis.While for the stage Ⅰ+Ⅱ,promoter hypermethyled genes such as p16,RASSF1A and FHIT likely more valuable than the used clinically CA125,CA19-9,CEA,NSE and CYFRA21-l,and the valuable index for the early diagnosis of lung cancer is p16.Conclusion:1. P16, RASSF1A and FHT gene promoter methylation in peripheral correlate with lung caner,There were no significant correlations between p16、 RASSF1A and FHIT methylation and histological type,clinical,gender,age and history.2. Assessment of gene promoter methylation, level using quantitative of p16、 RASSF1A and FHIT may be contribute to early diagnosis of lung cancer.