Adenoviral transfer of rho family proteins to lung cancer cells ameliorates cell proliferation and motility and increases apoptotic change.

Lung cancer is still a very severe disease which has a low survival rate due to local invasion and metastasis potentials in spite of many clinical challenges using anti-cancer drugs. Rho family small GTPases play pivotal roles in cell invasion and metastasis during carcinogenesis. In this study, we explored the inhibitory effect of adenoviral vector encoding dominant negative mutants of Rac, RhoA, and ROCK in human non-small cell lung carcinoma cell lines (A549 and SQ5) and mouse carcinoma cell line (Lewis lung carcinoma, LLC). These cells showed high expression of Rac, Rho, and ROCK, whereas only faint bands were detected in normal human lung epithelial cells, BET-1A. The efficiency of adenoviral vector transfer was stronger in A549 and SQ5 cells than LLC cells. Dominant negative forms of RhoA (Rho-DN) and Rac (Rac-DN) decreased cell proliferation in WST-8 assay and increased the number of apoptotic cells in both A549 and SQ5 cells by Hoechst 33258 and TUNEL staining. On the other hand, DN form of ROCK (ROCK-DN) did not show any apparent changes compared with the other proteins. Transwell chamber analysis showed that migration/invasion activity was significantly suppressed by gene transfection both in A549 and SQ5 cells and that ROCK-DN gene transfer required a higher multiplicity of infection to show effects similar to Rho and Rac. Although the effect of gene therapy is cell-dependent, these data suggest that adenoviral gene transfer with Rho family small GTPases is one good approach to lung cancer therapy.