Abstract: Objective To examine the expression level of let-7 precursor and K-ras in lung adenocarcinoma patients by real time-PCR,in order to explore their roles in lung adenocarcinoma initiation and development.Methods GAPDH was adopted as a control,we use real time PCR to examine the expression of let-7 precursor and K-ras in carcinomatous tissue and the around normal tissue respectively in 31 selected lung adenocarcinoma patients.Results Compared to the normal tissue,let-7 precursor expression was reduced about 61.29%,while K-ras expression were increased about 67.74%.The measured value of let-7 precursor and K-ras in carcinomatous tissue and the around normal tissue respectively carry on statistics analysis.Their difference has the remarkable statistics significance.The correlation between let-7 precursor and K-ras in the expression of carcinomatous tissue has the remarkable statistics significance.Conclusion Those results suggest that let-7 precursor or/and K-ras may play an certain cooperated role in the initiation and development of lung adenocarcinoma.

Key words: let-7 precursor, K-ras, microRNA, Lung cancer