Abstract: Objective To investigate the expression of CDC25A in non- small cell lung cancer (NSCLC) tissues and explore its correlation with the clinicpathological features of the patients and the expressions of let-7a1 and let-7c. Methods We collected surgical specimens of pathologically confirmed NSCLC tissues and paired adjacent lung tissues from 44 patients and tissues of benign lung lesions from 9 patients. The expressions of CDC25A protein and mRNA in the tissues were detected by immunohistochemistry and fluorescence quantitative RT-PCR, respectively; the expressions of let-7a1 and let-7c mRNA were detected using tail-adding fluorescence quantitative RT-PCR. Results The positivity rate of CDC25A protein expression was significantly higher in NSCLC tissues than in the adjacent tissues and benign pulmonary lesions (P<0.05). CDC25A protein expression in NSCLC was not correlated with the patients' age, gender, pathological type, degree of tumor differentiation, or clinical stages (P>0.05), and was significantly correlated with smoking and lymph node metastasis (P<0.05). CDC25A mRNA expression was also significantly higher in NSCLC tissues than in the adjacent tissues and benign pulmonary lesions (F=6.33, P<0.05), and was similar between the latter two tissues (P>0.05). Pearson correlation analysis showed that CDC25A expression had a significant negative correlation with let-7c expression in both NSCLC tissues (r=-0.42) and adjacent lung tissues (r=-0.40) but was not correlated with let- 7a1 expression. Conclusion The expression level of CDC25A is significantly increased in NSCLC with a negative correlation with Let-7c expression, which identifies CDC25A as a possible downstream target gene of Let-7c.

Key words: microRNA, let-7, non-small cell lung cancer, CDC25A