nm23-H1, a nucleoside diphosphate kinase (NDPK), enhances drug sensitivity and has antimetastatic activity, whereas focal adhesion kinase (FAK) is closely associated with cell migration and tumour spreading. The relationship between these two proteins, however, is not well elucidated. In this study, we investigate their correlation in patients with non-small cell lung cancer (NSCLC). Expressions of nm23-H1 and FAK were examined by reverse transcription-polymerase chain reaction and immunoblotting in surgical resections. The relationship between these two genes was assessed statistically. Patients were classified into four groups according to the expression of nm23-H1 and FAK by immunohistochemistry: FAK-negative/nm23-H1-positive, FAK-negative/nm23-H1-negative, FAK-positive/nm23-H1-positive and FAK-positive/nm23-H1-negative. Although the causal correlation is still uncertain, our results showed that protein expression of nm23-H1 was inversely correlated with that of FAK. The combined analysis of nm23-H1 and FAK protein expression in the same tumour specimens revealed that patients with FAK-negative/nm23-H1-postive tumours survived the longest, 56 months, among those with nm23-H1 and FAK features (P<0.001). Our data indicate that expressions of nm23-H1 and FAK are inversely correlated. These results suggest that the status of nm23-H1 and FAK protein expression may help in predicting the aggressive behavior of NSCLC. However, further studies are warranted to clarify the impact of FAK on the function of nm23-H1 as an anti-metastatic gene.

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