Prognostic value of MET, cyclin D1 and MET gene copy number in non-small cell lung cancer

The aim of this study was to analyze the correlation of the expression of MET and cyclin D1 and MET gene copy number in non-small cell lung cancer (NSCLC) tissues and patient clinicopathologic characteristics and sur-vival. Sixty-one NSCLC tissue specimens were included in the study. The expression of MET and cyclin D1 was evaluated by immunohistochemistry and MET gene copy number was assessed by quantitative real-time polymer-ase chain reaction (Q-PCR). Positive expression of MET and cyclin D1 protein and increased MET gene copy number occurred in 59.0%, 59.0% and 18.0% of 61 NSCLC tissues, respectively. MET-positivity correlated with poor differentiation (P = 0.009). Increased MET gene copy number was significantly associated with lymph node metastasis (P = 0.004) and advanced tumor stage (P = 0.048), while the expression of cyclin D1 was not associ-ated with any clinicopathologic parameters. There was a significant correlation between the expression of MET and MET gene copy number (P = 0.002). Additionally, the expression of cyclin D1 had a significant association with the expression of MET as well as MET gene copy number (P = 0.002 and P = 0.017, respectively). MET-positivity and increased MET gene copy number were significantly associated with poor overall survival (P = 0.003 and P < 0.001, respectively) in univariate analysis. Multivariate Cox proportional hazard analysis confirmed that the expression of MET and MET gene copy number were prognostic indicators of NSCLC (P = 0.003 and P = 0.001, respectively). The overexpression of MET and the increased MET gene copy number might be adverse prognostic factors for NSCLC patients. The activation of the MET/cyclin D1 signaling pathway may contribute to carcino-genesis and the development of NSCLC, and may represent a target for therapy.