Relationship Between EIF3a And CTR1Genetic Variations And Platinum-based Chemotherapeutic Efficacy And Prognosis In Patients With Lung Cancer

SECTION1Relationship between eIF3a genetic polymorphisms and Platinum-based chemotherapeutic response in patients with lung cancerPlatinum response severely impedes successfully chemotherapy in lung cancer patients. Nucleotide excision repair (NER) pathway is considered as one of the major factors contributing to platinum effects. Furthermore, genetic variances of NER pathway influence platinum response. eIF3a is the largest subunit of eukaryotic translation initiation factor3, which has been suggested to affect tumor progression and activity of nucleotide excision repair pathway contributing to platinum resistance. eIF3a, over expressed in many malignancies, is an up-stream gene of NER and could regulate its activity. The purpose of this study is to investigate,1) whether eIF3a mutations or genetic polymorphismsstatus have prognostic and predictive significance in platinum-based chemotherapeutic lung cancer patients,2) whether eIF3a polymorphism is associated with severe platinum toxicity in non-small cell lung cancer (NSCLC) patients.771lung cancer patients were enrolled. These patients were newly diagnosed with incident lung cancer, which was confirmed histologically or cytological and accepted platinum-based chemotherapy for at least two cycles. Among these,282incident NSCLC patients, from three different institutions, were enrolled and followed up. These patients were diagnosed and histologically confirmed with non-small cell lung cancer. All patients accepted platinum-based chemotherapy for at least two cycles. Twenty-two SNPs of eIF3a were detected in these patients. Three novel mutations of eIF3a were found, including11279G>A in intron6, Arg438Lys in exon9,29671G>A in intron15, with minor allele frequency of0.16,0.18,0.16, respectively. A-carrier patients of rs3740556conferred a significantly better platinum-based chemotherapy response (p<0.05) and seemed to live longer. eIF3a Arg803Lys C>T polymorphism is associated with cisplatin-induced toxicity in NSCLC patients (p=0.02, OR=0.54,95%CI [0.32-0.93]). T-carrier subjects presented better tolerance to platinum nephrotoxicity, but poorer tolerance to ototoxicity.eIF3a genetic polymorphisms can be considered as predictive tools for pretreatment evaluation of platinum-based chemotherapy. Lung cancer patients carrying rs3740556A allele tended to have a favorable prognosis after treatment with platinum-based chemotherapy. eIF3a Arg803Lys was associated with platinum toxicity in NSCLC patients, and could be considered as a predictor for pretreatment evaluation in lung cancer patients. SECTION2Relationship between CTR1genetic polymorphisms and Platinum-based chemotherapeutic response in non-small cell lung cancer patientsChemotherapeutic resistance to platinum-based anticancer drugs, as well as severe toxicity is a major obstacle in the successful treatment in lung cancer.Cellular uptake and platinum accumulation are considered the most important factors contributing to platinum resistance. The copper transporter family is the major plasma membrane transporter for platinum uptake. Copper transporter protein1(CTR1) plays an essential role in cisplatin influx and is closely related to platinum resistance by influencing platinum uptake and accumulation. Genetic variances of certain core genes have also been suggested to effect on platinum induced toxicity. The aim of the present study was to determine,1) whether CTR1genetic polymorphisms are associated with platinum resistance in non-small cell lung carcinoma (NSCLC) patients,2) whether CTR1polymorphism is associated with platinum toxicity in NSCLC patients.A total of282incident Chinese Han NSCLC patients were enrolled in the study and followed up at three different institutions. All patients underwent at least two cycles of platinum-based chemotherapy. Among these,204incident NSCLC patients have accepted cisplatin-based chemotherapy for at least two cycles. Other patients were treated based on carboplatin. Twenty CTR1single-nucleotide polymorphisms (SNP) were detected from genomic DNA samples.Genetic polymorphisms of CTR1at rs7851395and rs12686377were associated with platinum resistance in NSCLC patients. Patients with a GT haplotype presented with increased susceptibility to platinum resistance (P<0.05), whereas an AG haplotype contributed to longer survival time (P<0.05). CTR1rs10981694A>C polymorphism is associated with cisplatin induced severe toxicity in NSCLC patients. C-carrier subjects presented poorer tolerance to ototoxicity (p<0.05). The survival times of patients with different rs10981694genetic polymorphism were not significantly different.In conclusion, a significant relationship was found between rs7851395and rsl2686377polymorphisms and platinum resistance, as well as clinical outcomes, in Chinese NSCLC patients. NSCLC patients carrying C allele of CTR1rs10981694presented more sensitivity to ototoxicity after cisplatin treatment. Thus, CTR1gene plays an essential role in platinum resistance and could be considered a predictive marker for pretreatment evaluation of NSCLC patients. SECTION3The effect of docetaxel on eIF3a gene expression in human non-small cell lung cancer A549cell lineDocetaxel is widely used in chemotherapy of non-small cell lung carcinoma (NSCLC), which is also the first choice for lung cancer patients resistant with cisplatin. Docetaxel binds to microtubules reversibly with high affinity and prevent physiological microtubules disassembly resulting in inhibition of mitotic cell division and preventing cancer cell progeny further.While, both a-tubulin and β-tubulin is the major composition in formation of microtubules. The eukaryotic initiation factors (elFs) play an essential role in translation initiation and regulations. eIF3is the largest and most complex one in this family and contains13subunits. Recent researches indicate that eIF3a, over-expressed in various carcinomas, could affect the translation initiation and regulations, cell circle regulations and malignant phenotype maintenance significantly. Recently, data from our laboratory showed that eIF3a is closely related to the chemotherapy resistance of cisplatin in lung cancer patients. Furthermore, eIF3a could interact with a-tubulin in case of treated by mimosine which could block cell cycle at G1phase In this study, we aimed to explore whether docetaxel has an effect of anti-cancer function via modulating eIF3a expression and the relationship between eIF3a and a-tubulin expression in the treatment of docetaxel.The human lung cancer cell line A549was treated withdocetaxel in form of different dosages for different times. The cells growth in the log phase were placed in6-well plates, washed twice by PBS, and treated by docetaxel with different dosages of10μg/L,15μg/L,20μ/L,25μg/L and30μg/L, respectively. Then, the cells treated with each different dosage of docetaxel were incubated for another1h,2h,4h,6h,10h,12h, and24h at37℃, respectively. The control groups were treated without docetaxel as described above. Real-time PCR and Western Blot were performed to detect the expression level of eIF3a mRNA and protein expression levels of eIF3a and a-tubulin, respectively.Docetaxel could not affect a-tubulin expression in neither mRNA levels nor protein levels. After A549cells were treated with high dose of docetaxel (30μg/L), there was an increased tendency in the expression level of eIF3a mRNA as treated time was lengthened. In addition, the protein expression level of a-tubulin was significantly not associated with eIF3a expression in cells treated by docetaxel.In conclusion, in this study, we, for the first time, explored the relationship among eIF3a, a-tubulin and docetaxel. Docetaxel could slightly increase the expression of eIF3a mRNA, and eIF3a could not regulate the expression of a-tubulin in A549cells treated by docetaxel.