A Case-control Study On The Genetic Variants In The Promoter Of Pin1 Gene And The Risk Factors Of Human Lung Cancers

Lung cancer is a common malignamt tumor of hunman being. In recent decades,the death rate of lung cancer has been increased very quiekly either in developing or less developed countries. As the record of WHO showed in 2005,it also had become the most universal cancer in male and the secondary mortality in female which was followed breast cancer. In China, lung Cancer had been the first cause of death for many years as we all know. However, the mechanism of how lung cancer developed is still unclear. Pin1 is a newly identified peptidyl-prolyl cis/trans isomerase (PPIase) that specifically regulates the conformation of Pro-directed phosphorylation sites, revealing a new postphosphorylation regulatory mechanism. Pin1-induced conformational change potentiates multiple oncogenic signaling pathways, and Pin1 overexpression is reported as a prevalent and specific event in human cancers. We hypothesis that the polymorphisms in the promoter regions of Pin1 gene was associated with risk of lung cancer. In this study, we tested the hypothesis in current hospital-based case-control study with 808 lung cancer cases and 808 age-sex frequency-matched controls in southern Chinese, and further investigated the association between the enviromental factors and the risk of lung cancer. Part one. A Case-Control Study of Human Lung cancersObjective: To investigate the risk factors of human lung cancers in Guangzhou,and to provide the scientific basis for controlling and preventing lung cancer.Methods: 808 newly diagnosed primary lung cancer cases according to the bronchoscope and pathologic diagnoses and equal number of control, matched for age and sex, were recruited and interviewed in Guangzhou during 2006 to 2009. The questionnaire consists of 91 items about lung cancer aetiological factors was applied.Single-factor and multivariate conditional logistic regression were performed to calculate the ORs and their 95% C.I.Result: In the single-factor analysis,19 factors were found to be associated with the risk of lung cancer. By multivariate analysis, six main risk factors were ascertained, there were: Smoking (adjusted OR=2.49, 95%CI=1.86-3.35), Exposure to environmental tobacco smoke(ETS ) from parents (adjusted OR=2.23, 95%CI=1.58-3.15), COPD(adjusted OR=1.50, 95% CI=1.04-2.16), Family history of lung cancer (adjusted OR=1.77,95%CI=1.20-2.60) , Occupational exposure to metal poisons (adjusted OR=2.17, 95%CI =1.25-3.76), Iatrogenic exposure to X-ray (adjusted OR=1.92, 95%CI=1.33-2.76). And two protective factor were: equipment of exhaust fan or pipe ( adjusted OR=0.46, 95%CI =0.32-0.67), Oftern eating fresh vegetables and fruit (adjusted OR=0.25, 95%CI =0.19-0.34).Conclusion: The result indicated that the environment risks which associate with lung cancer are the same as results of the original study, where the value of ORs have degraded.And lung cancer is one of preventable disease. Part Two. A case-control study on the genetic variants in the promoter of Pin1 gene and the risk factors of human lung cancersObjective:In this study, we tested the hypothesis that common polymorphisms in the promoter regions of Pin1 are associated with risk of lung cancer. We genotyped two Pin1 polymorphisms (-842G>C, -667C>T) in a hospital-based case-control study with 808 patients of lung cancer and 808 cancer-free control subjects. Further study is carried to discover the association between the co-operation of the genetic variance in Pin1 promoter region as the enviromental factors and lung cance. This may help us to screen the possible susceptibility marker of lung cancer in Chinese southern people.Methods:Based on the integrity information of investigation, each subject was asked to donate 5 mL of blood after giving informed consent. DNA was extracted and separated as work solution and stock solution. Biophtometer 6131 was used to detect the concentration and purity of DNA. Based on the Genebank dbSNP database (http://www.ncbi.nlm.nih.gov), according to the principle that the minor allele frequency >5%. We identified two possible functional SNPs in the Pin1 gene promoter region, they were: -842G>C [rs2233678] and -667C>T [rs2233679]. PCR-RFLP was carried out to analyse the genotype and a little samples were sequenced by Invitrogen company.Result:The observed genotype frequency of -667C>T among the controlsubjects was in agreement with the Hardy–Weinberg equilibrium (P=0.73), however, -842G>C wasn't (P=0.02). The pairwise LD analyses in the controls showed that all 2 polymorphisms were in a relatively low linkage disequilibrium (D'= 0.022 and r2 = 0.001).The difference in the observed genotype frequency of two SNPs among case and control were statistically significant. Compared with the-842GG genotype, -842TG heterozygotes had a 0.62-fold decreased risk of lung cancer (adjusted OR=0.62;95%CI=0.45-0.85;P=0.003), and the association between the-842CC homozygote and the degraded risk of lung cancer was significantly critical value.(adjusted OR=0.39;95%CI=0.14-1.12;P=0.079). The carriers of-842 C(-842GC and -842CC )variant allele had a 0.60-fold decreased risk of lung cancer. There was a significant trend for an allele dose effect on risk of lung cancer (Ptrend =0.0007). Compared with the-667CC genotype, the association between the-667CT heterozygotes and the degraded risk of lung cancer was significantly critical value.(adjusted OR=0.81; 95%CI=0.64-1.03;P=0.083).-667TT homozygote had a 0.61-fold decreased risk of lung cancer (adjusted OR=0.61;95%CI=0.44-0.83;P=0.002), and the carriers of-667 T(-667TT and -667CT)variant allele had a 0.75-fold decreased risk of lung cancer(adjusted OR=0.75; 95%CI=0.60-0.94;P=0.0013). There was a significant trend for an allele dose effect on risk of lung cancer (Ptrend =0.0017).To determine the combined effects of the two promoter SNPs, we divided the observed genotype into two classes according to the variant number of two SNPs. We found that the carriers with variant﹥1 had a 0.63-fold decreased risk of lung cancer compared with the carriers with variant less than 1 or equal 1.We performed a stratification analysis of the associations between Pin1 variant genotypes and the risk of lung cancer in subgroups by age, sex, smoking and alcohol drinking, BMI, The two SNPs was associated with the decreased risk of lung cancer too,all the ORs<1.00.Conclusion:The Pin1 -842G>C and -667C>T variants can significantly decrease the risk of lung cancer in Southern Chinese.