Effects of miRNA-149-5p and Platelet-Activating Factor-Receptor Signaling on the Growth and Targeted Therapy Response on Lung Cancer Cells.

Accumulating evidence indicates that microRNAs (miRs) play critical roles in essentially all biological processes and their altered expression has been documented in various disease conditions, including human malignancies. Although several cellular mechanisms have been identified in mediating the effects of miRs, the involvement of G-protein-coupled, platelet-activating factor-receptor (PAFR) signaling in miR-149-5p-induced effects on lung cancer growth and therapeutic potential has not been studied. To that end, we first evaluated the functional significance of PAFR and miR-149-5p in A549 and H1299 human non-small cell lung cancer (NSCLC) cell lines. We observed that these tumor lines express endogenous PAFR and miR-149-5p and that PAFR activation by PAF agonist (CPAF) significantly increased, whereas miR-149-5p mimic transfection inhibited cell proliferation in a dose-dependent manner. Interestingly, miR-149-5p mimic significantly attenuated CPAF-mediated increased proliferation of NSCLC cells, as confirmed by miR-149-5p, cyclin D1, and forkhead box protein M1 (FOXM1) expression analysis via qPCR. Our next studies examined PAFR- and miR-149-5p-mediated effects on targeted therapy (i.e., erlotinib and gefitinib) responses. We observed that erlotinib and gefitinib inhibited A549 and H1299 cell survival in a dose- and time-dependent manner, and CPAF significantly blocked this effect. These findings indicate that miR-149-5p blocks PAFR-mediated increased cell proliferation, and PAFR activation attenuates the cytotoxic effects of targeted therapy.