Effect Of C-Myc Gene Expressing On Clinical Prognosis Of Non-small Cell Lung Cancer After Surgical Treatment

ObjectiveTo analyze the prognostic factors associated with surgical treatment of non-small cell lung cancer(NSCLC),and to explore the effect of c-Myc gene expressing on long-term survival in patients with NSCLCMethodsA total of 84 patients with NSCLC,who received surgical treatment and confirmed by pathological examination in the first affiliated hospital of Nanjing Medical University in December 2011-June 2012,were included to retrospectively analyze the clinical data.All survival data were collected by telephone and outpatient follow-up(survival time is measured as month).Age,gender,smoking history,pathological pattern,surgical procedures,pathological stage,chemotherapy after operation,lymphatic metastasis and gene expression of c-Myc were selected as influence factors.The expression levels of c-Myc mRNA in 84 NSCLC tissues and the corresponding para-cancerous tissues were detected by RFQ-PCR(real-time fluorescence quantitative-PCR).C-Myc siRNA was transfected into NSCLC H1299 cells by LipofectAMINE 2000.The expression level of c-Myc mRNA in H1299 cells after transfection with siRNA was detected by RT-PCR,and the proliferation of H1299 cells was detected by CCK-8(Cell Counting Kit-8).Cisplatin toxicity experiments further validated effect of killing tumor cells with c-Myc gene silence.Single factor significance was analyzed by Long-Rank Methods,Multi-factors survival was analyzed by COX proportional hazards regression models.A paired t-test was employed to analyze the expression levels of c-Myc mRNA.One-way analysis of variance was applied to the results of cell proliferation and cisplatin cytotoxicity experiments.All analyses were performed using SPSS 19.0 software(SPSS Inc.,Chicago,IL,USA).Data are presented as the mean±standard deviation(SD).P<0.05 was considered as statistically significant.Results(1)Significantly higher c-Myc mRNA levels were detected in tumor specimens than in adjacent areas(P<0.05).Moreover,the of c-Myc mRNA expression in NSCLC tissues(6.28 × 103)was 1.77-fold higher than that in adjacent tissues(3.54 × 103)and had no correlation to sex,age,histological type,clinical stage,or lymph node metastasis.(2)C-Myc siRNA was successfully transfected into NSCLC H1299 cells.After transfection,the expression level of c-Myc mRNA was down-regulated in H1299 cells.The proliferation rates of H1299 cells after transfection with c-Myc siRNA for 24,48 and 72 h were lower than those of the cells without transfection(P<0.05).Effect of killing tumor cells with gene silencing was comparable with cisplatin,and can also increased when the c-Myc gene silencing and cisplatin were in combination.(3)There were 82 patients(97.62%)whose survival time was 6 months,76 patients(90.48%)whose surval time was 12 months,55 patients(65.48%)whose survival time was 3 years,and 31 patients(36.90%)whose surval time was 4 years.(4)Single factor analysis results showed that the survival time in patients with different years old were significantly differently(P<0.05),the survival time in patients with different gender were significantly differently(P<0.05),the survival time in patients with and without smoking history were significantly differently(P<0.05),the survival time in patients with different pathological patterns were not significantly differently(P>0.05),the survival time in patients with different TNM tumor stage were significantly differently(P<0.05),the survival time in patients with different lymphatic metastasis were significantly differently(P<0.05),the survival time in patients with different chemotherapy condition after operation were significantly differently(P<0.05),the survival time in patients with different gene expression level of c-Myc were significantly differently(P<0.05),and the survival time in patients with different surgical methods were not significantly differently(P>0.05).(5)COX proportional hazards regression analysis showed that gender,tumor TNM stage,lymphatic metastasis,chemotherapy after operation and gene expression level of c-Myc were influence factors to the survival of patients with NSCLC.Conclusion(1)The expression level of c-Myc mRNA in NSCLC tissues is higher than that in the corresponding para-cancerous tissues.The lower expression of c-Myc can inhibit significantly NSCLC H1299 cells.(2)Gender,pathological stage,chemotherapy after operation,lymphatic metastasis and gene expression level of c-Myc were influence factors to the survival of patients with NSCLC.Female patients with early pathological stage,and low gene expression level of c-Myc have the higher survival rate and chemotherapy can improve their clinical prognosis.(3)Radical operation procedures were not the individual influence factors to clinical prognosis in patients with NSCLC,and the radical operation procedure should be selected according to the conditions of individual patients.