pf-3758309 and Carcinoma--Non-Small-Cell-Lung

Risk classification on the basis of specific genomic features can lead to more precise tailoring of treatment for cancer patients. Kinases are potential therapeutic targets and survival factors, but the predictive prognostic potentials of multi-kinase genes have seldom been investigated. In this study, with publicly available microarray data of non-small cell lung cancers (NSCLC), we identified two kinase genes cyclin-dependent kinase 2 (CDK2) and p21 protein (Cdc42/Rac)-activated kinase 4 (PAK4) significantly associated with poor outcome. Then we present a combined gene signature model using CDK2 and PAK4 that can stratify disease poor outcome independently of standard clinical prognostic factors. Next, the predictive robustness of this 2-gene classifier was in silico confirmed in an independent microarray dataset, and experimentally validated in a lung cancer cohort by immunohistochemistry. Therefore, in this study, we demonstrated that the CDK2-PAK4 kinase signature may be a useful prognostic indicator and potential target for NSCLC. We also propose that poor outcome subgroup stratified by this classifier may benefit from the recently developed CDK2 and PAK4 inhibitors.

Topics: Aged; Carcinoma, Non-Small-Cell Lung; Cyclin-Dependent Kinase 2; Disease-Free Survival; Female; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Lung Neoplasms; Male; Middle Aged; p21-Activated Kinases; Pyrazoles; Pyrroles; Tissue Array Analysis; Treatment Outcome

Epidemiological data clearly establishes cigarette smoking as one of the major cause for lung cancer worldwide. Recently, targeted therapy has become one of the most preferred modes of treatment for cancer. Though certain targeted therapies such as anti-EGFR are in clinical practice, they have shown limited success in lung cancer patients who are smokers. This demands discovery of alternative drug targets through systematic investigation of cigarette smoke-induced signaling mechanisms. To study the signaling events activated in response to cigarette smoke, we carried out SILAC-based phosphoproteomic analysis of H358 lung cancer cells chronically exposed to cigarette smoke. We identified 1,812 phosphosites, of which 278 phosphosites were hyperphosphorylated (≥ 3-fold) in H358 cells chronically exposed to cigarette smoke. Our data revealed hyperphosphorylation of S560 within the conserved kinase domain of PAK6. Activation of PAK6 is associated with various processes in cancer including metastasis. Mechanistic studies revealed that inhibition of PAK6 led to reduction in cell proliferation, migration and invasion of the cigarette smoke treated cells. Further, siRNA mediated silencing of PAK6 resulted in decreased invasive abilities in a panel of non-small cell lung cancer (NSCLC) cells. Consistently, mice bearing tumor xenograft showed reduced tumor growth upon treatment with PF-3758309 (group II PAK inhibitor). Immunohistochemical analysis revealed overexpression of PAK6 in 66.6% (52/78) of NSCLC cases in tissue microarrays. Taken together, our study indicates that PAK6 is a promising novel therapeutic target for NSCLC, especially in smokers.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cell Survival; ErbB Receptors; Gene Silencing; Humans; Lung Neoplasms; Male; Mice; Mice, Inbred NOD; Mice, SCID; Neoplasm Transplantation; p21-Activated Kinases; Phosphorylation; Proteome; Pyrazoles; Pyrroles; rac1 GTP-Binding Protein; RNA, Small Interfering; Signal Transduction; Smoke; Tobacco Products