ABSTRACT
Deregulation of the microRNAs (miRNAs), a cluster of important posttranscriptional regulators, has been frequently associated with lung cancer (LCa). However, the emerging mechanism for how miRNAs is linked causally in the development of LCa chemoresistance is poorly understood. Herein, we established for the time the up-regulation of miR-369-3p in cisplatin (DDP)-resistant nonsmall cell lung cancer (NSCLC) tissues and cells. Its deregulation was found to be correlated to the magnitude of malignancy in well-characterized LCa cells. Functionally, inhibition of miR-369-3p sensitized LCa cells to DDP and suppressed the invasive capability in the presence of DDP treatment, whereas miR-369-3p overexpression promoted DDP resistance and thereby enhanced LCa cells invasiveness. Mechanistically, bioinformatics coupled with luciferase and gain-of-function, loss-of-function assays revealed that miR-369-3p may regulate DDP chemoresistance by directly targeting the 3' untranslated region (UTR) of human solute carrier 35F5 (SLC35F5), as application of miR-369-3p inhibitors or reintroduction of epigenetically silenced SLC35F5 both individually sensitized LCa cells to DDP, but combined treatment with miR-369-3p inhibitors and SLC35F5 overexpression failed to sensitized LCa cells further to DDP-elicited cell death. Our results provide evidence that the oncomiR effect of miR-369-3p may be mediated through disrupting the nucleotide sugar transportation and that SLC35F5 is a key effector of this chemoresistance-promoting activity.
