Inhibition of rhotekin exhibits antitumor effects in lung cancer cells

Lung cancer is the leading cause for cancer-related death, however, the pathogenesis mechanism is poorly understood. Although the rhotekin (RTKN) gene has been reported to encode an effector for the Rho protein that has critical roles in regulating cell growth, the role of RTKN in lung cancer has not been investigated. In clinical lung cancer patient tumor samples, we identified that the RTKN gene expression level was significantly higher in tumor tissues compared to that of the adjacent normal tissues. To investigate the molecular mechanisms of RTKN in lung cancer, we established RTKN stable knock-down A549 and SPC-A-1 lung adenocarcinoma cell lines using lentiviral transfection of RTKN shRNA and evaluated the antitumor effects. The results showed that RTKN knock-down inhibited lung adenocarcinoma cell viability, induced S phase arrest and increased cell apoptosis. In addition, RTKN knock-down inhibited lung cancer cell invasion and adhesion. Further analysis showed that the S phase promoting factors cyclindependent kinase (CDK)1 and CDK2 levels were decreased in RTKN knock-down cells, and that the DNA replication initiation complex proteins Minichromosome maintenance protein complex (MCM)2 and MCM6 were decreased as well in RTKN knock-down cells. These results indicated that the RTKN protein was associated with lung cancer in clinic samples and exerted anticancer activity in lung adenocarcinoma cells through inhibiting cell cycle progression and the DNA replication machinery. These findings suggest that RTKN inhibition may be a novel therapeutic strategy for lung adenocarcinoma.