Activation of KIF4A as a prognostic biomarker and therapeutic target for lung cancer.

To identify molecules that might be useful as diagnostic/prognostic biomarkers and as targets for the development of new molecular therapies, we screened genes that were highly transactivated in a large proportion of 101 lung cancers by means of a cDNA microarray representing 27,648 genes. We found a gene encoding KIF4A, a kinesin family member 4A, as one of such candidates. Tumor tissue microarray was applied to examine the expression of KIF4A protein and its clinicopathologic significance in archival non-small cell lung cancer (NSCLC) samples from 357 patients. A role of KIF4A in cancer cell growth and/or survival was examined by small interfering RNA experiments. Cellular invasive activity of KIF4A on mammalian cells was examined using Matrigel assays. Immunohistochemical staining detected positive KIF4A staining in 127 (36%) of 357 NSCLCs and 19 (66%) of 29 small-cell lung cancers examined. Positive immunostaining of KIF4A protein was associated with male gender (P = 0.0287), nonadenocarcinoma histology (P = 0.0097), and shorter survival for patients with NSCLC (P = 0.0005), and multivariate analysis confirmed its independent prognostic value (P = 0.0012). Treatment of lung cancer cells with small interfering RNAs for KIF4A suppressed growth of the cancer cells. Furthermore, we found that induction of exogenous expression of KIF4A conferred cellular invasive activity on mammalian cells. These data strongly implied that targeting the KIF4A molecule might hold a promise for the development of anticancer drugs and cancer vaccines as well as a prognostic biomarker in clinic.