Study On Gene Polymorphism Of Non - Small Cell Lung Cancer In Predicting Prognosis And Prognosis

Objective:Lung cancer is the common malignant tumort which hreatening human health, theincidence and mortality of lung cancer in a rising trend worldwide, it is also rapidupwardtrend in China. Non-small cell lung cancer counted for80%-85%of lung cancer. Due to the low early diagnosis rate, most of patients lost theopportunity of operation, so the chemotherapy is the only choice. At present, cisplatinbased chemotherapy is the most common method, but there was no significantdifference between various schemes, studies have shown that the effect ofchemotherapy and prognosis of lung cancer may be related to gene mutationand expression level. Single nucleotide polymorphism (SNP), mainly refers to theDNA sequence polymorphism in genomic level caused by single nucleotidemutation. It is one of the most common heritable variation in the humangenome, accounting for more than90%of all known polymorphism. Itcan affect gene expression. Single nucleotide polymorphisms of DNA repairgene makes the repair enzyme diversity, and makes DNA repair capacity ofindividual diversity. While the DNA repair capacity is the root cause of platinumbased chemotherapy sensitivity differences. In the process of chemotherapy，platinum combined with tumor cells DNA into platinum–DNA adducts, cause DNAinterstrand cross links, block DNA replication, prevent tumor cell division. DNArepair system in the human body can eliminate the platinum–DNA adducts, takePt-DNA returned to normal, treatment effect reduced. The weaker DNA repaircapacity is, the patient is more sensitive to platinum drug treatment. Xerodermapigmentosum gene D (XPD), excision repair cross complementing gene1(ERCC1), breast cancer susceptibility gene1(BRCA1) are associated with DNArepair pathway, can affect the platinum drugs inhibiting DNA replication effect. Atpresent the related research about the effect of chemotherapy and these three genes innon-small cell lung cancer and prognosis is less.The main purpose of this study is to:(1) find out the frequency distribution of the XPD gene, ERCC1gene, BRCA1 gene in population of North China;(2) to understand the distribution of XPDgene, ERCC1gene, BRCA1gene in patients of different age, different gender，andthe association between gene type and clinical stage，or pathological type, or theeffect of chemotherapy;(3) to analyze the influence of the chemotherapy effect;(4) toanalyze the influence of prognosis of patients after chemotherapy.Methods:The study period was from October2005to Otober2006, and284NSCLC patientswere enrolled within one month after being diagnosed with NSCLC. All thepatients treatment for platinum based chemotherapy. Patients in group were stage inⅢB or Ⅳ. EDTA-Na2anticoagulation tube was used to sampling peripheral venousblood and DNA was extracted. Taqman probe method was used to detection thepolymorphism of XPD Lys751Gln (rs13181)， ERCC1Asnll8Asn(rs11615)，BRCA1Serl613Gly (rs1799966). After DNA amplification，fluorescence signal wascollected by PCR instrument. Genotype distribution plot was drew.Genotype distribution of XPDLys751Gln，ERCC1Asnll8Asn，BRCA1Serl613Glywas analyzed，influence factors related to the effect of chemotherapy and prognosiswas discussed either.Results:(1) XPD Lys751Gln AA type，AC type，CC type gene proportion was76.41%，20.77%，2.82%respectively; A allele frequency was86.80%, C allele was13.20%. ERCC1Asn118Asn CC type, CT type, TT type gene proportion was62.68%,31.34%,5.99%respectively; allele C and the frequency of T was78.35%,and21.65%respectively. BRCA1Ser1613Gly AA type, AG type, GGtype genes accounted for40.49%,50.70%, and8.80%; allele A and the frequency ofG were65.85%and34.15%.(2) The AA and AC+CC genotypes of XPD Lys751Gln gene was found nodifference in different age groups, different genders, different pathological type anddifferent chemotherapeutic effect (P>0.05). But genotype distribution in patients with different stages was significantly different, higher proportion ofAA genotypes in stage ⅢB than in stage Ⅳ (χ2=27.692, P=<0.001).(3)Between different age groups, different genders, different effect ofchemotherapy and different stages，there was no difference was found in the CC andCT+TT genotypes of ERCC1Asn118Asn gene distribution (P>0.05). Butgenotype distribution in patients with different pathological types has statisticalsignificance difference，CC genotype in patients with adenocarcinoma accounted for76.81%, CT+TT genotype was23.13%, however，the proportion of CC genotypeand CT+TT in patients with squamous cell carcinoma was50.52%and49.48%respectively, there may be correlation between genotype and pathological types (χ2=24.335, P <0.001)(4) Between different gender, different pathological type and different clinical stagesthere was no difference was found in AA and AG+GG genotypes ofBRCA1Ser1613Gly distribution (P>0.05)， but patients with different age (χ2=13.322, P=0.001). patients age less than35with AA genotype was accounted for63.64%,35-59group of patients with AA genotype was accounted for43.24%,60years old group was29.13%, AA genotype proportion is higher in patients with lowage, AG+GG genotype proportion is higher in patients elderly. In addition, genotypeof BRCA1Ser1613Gly is associated with the effect of chemotherapy, in partialresponse and stable patients, AA genotype accounted for relatively low, respectively30.88%and34.68%, AG+GG genotype accounted for a higher proportion, are closeto60%, but in the progression patients, AA genotype proportion is55.43%, theproportion of AG+GG is44.57%, different genotype distribution in patients withdifferent chemotherapy effect was statistically significant (χ2=12.871, P=0.002)(5) Single factor non-conditional logistic regression results showed that no influencefactor on chemotherapy effect was found， but BRCA1Ser1613Gly, age andclinical tage (P<0.05). Chemotherapy benefit increased in patients witnBRCA1Ser1613Gly AG+GG gene type than in AA genotype (OR=4.249，OR95%C.I.=1.927-9.366)； with the increase of age, chemotherapy benefit also increased (OR=3.194，OR95%C.I.=1.200-8.501)； compared with the patients ofstage Ⅲ B， chemotherapy benefit reduce in patients of stage IV (OR=0.882，OR95%C.I.=0.778-0.998). According to multivariate logistic regressionanalysis results， age and clinical stage has no influence on the effect ofchemotherapy (P>0.05)， while the BRCA1genotypeproduces an impact on the effect of chemotherapy， AG+GG genotype than in AAgenotype benefit rate increased3.849times (OR=3.846, OR95%C.I.=1.718-8.609).(6) After36months follow-up,156deaths(54.93%), lost6people (2.11%),121(42.61%) survived in284patients. Single factor analysis wascarried out by using Kaplan-Meier method, log-rank method used in the statistical test,results showed that XPD Lys751Gln gene，ERCC1Asn118Asn gene，gender，pathological type， clinical stage were not correlated with survival time (P>0.05), while the BRCA1Ser1613Gly gene and age were influence factor on survivaltime, survival time of patients with BRCA1Ser1613Gly AG+GG genotype or the lowage was longer. The multi factor COX regression analysis was usedfurther, compared with BRCA1genotype of the AA gene in patients，patients withAG+GG genotype, the risk of death within36months after chemotherapy increase0.321times (OR95%C.I.=0.112-0.992).Conclusions:(1) No difference between genders of XPD Lys751g Gln gene,ERCC1Asn118Asn,BRCA1Ser1613Gly in genotype distribution. Nodifferences among different ages of XPD Lys751Gln andERCC1Asn118Asn genotype distribution.(2) BRCA1Ser1613Gly gene was influence on the effect of chemotherapy for non-small-cell lung cancer, the chemotherapy benefit was significantly higher in patientswith AG+GG genotype than inAA genotype，it is may have a certain guiding for thefuture individual chemotherapy.(3) BRCA1Ser1613Gly gene was the factor which impact on survival timein non-small cell lung cancer patients after chemotherapy，compared with patients carrying AA genotype of BRCA1， AG+GG genotype in patients reduce the risk ofdeath. BRCA1Ser1613Gly genotype could be the prognosis indicatorsin chemotherapy patients. Objective:Lung cancer is the most common malignancy and clinical cancer mortality in thefirst place. Chemotherapy is the important measures in patients with non-small celllung cancer (NSCLC), and platinum-based two-drug combination chemotherapy isthe current standard first-line chemotherapy for NSCLC. However, there aresignificant differences between the chemosensitivity of different NSCLC patients.The prediction of the sensitivity of NSCLC chemotherapy is of great significance inguiding the selection and implementation of individualized treatment. The aim of thepresent study is to investigate the effects of the single-nucleotide polymorphisms(SNPs) XRCC1Arg194Trp, XRCC1Arg280His, XRCC1Arg399Gln, XRCC3Thr241Met, XPG His104Asp, and XPG His46His in genes involved in theDNA-repair pathway on the outcomes and the survival of platinum-basedchemotherapy in patients with non-small cell lung cancer (NSCLC).Methods:The study period was from January2005to January2006, and274NSCLCpatients were enrolled within one month after being diagnosed with NSCLC.Genomic DNA was extracted using the Qiagen Blood Kit (Qiagen, Chastworth, CA).Polymerase chain reaction (PCR) combined with a restriction fragment lengthpolymorphism (RFLP) assay was used for genotyping. The association betweengenotypes and curative effect of platinum-based chemotherapy or survival time wasexplored.Results:Individuals with the XRCC1399A/A genotype had a higher probability ofresponding well to platinum-based chemotherapy, indicated by an odds ratio (OR) of3.51(95%confidence interval [CI],1.50-8.37). Similarly, the XPG T/T genotype wassignificantly associated with improved responses to chemotherapy, indicated by an OR of1.92(95%CI,1.03-3.53). The XRCC1399A/A genotype was significantlyassociated with longer disease-free survival (DFS) and overall survival (OS),indicated by hazard ratios (HRs) of0.16(95%CI,0.11-0.66) and0.28(95%CI,0.11-0.66), respectively. Moreover, the XPG46T/T genotype increased the likelihoodof longer DFS and OS of NSCLC patients treated with platinum-based chemotherapy(HR,0.25;95%CI,0.12-0.52and HR,0.53;95%CI,0.27-0.96, respectively).Conclusions:These results indicate that XRCC1Arg399Gln and XPG His46His mightsignificantly affect the clinical outcomes of platinum-based chemotherapy, and XPCLys939Gln might be a prognostic marker of survival for non-small-cell lung cancerpatients receiving platinum-base chemotherapy, which highlight the need for largerstudies to confirm the role of these two SNPs in outcomes of NSCLC treatments.