MicroRNAs (miRNAs) are endogenous small noncoding RNA molecules involved in modulation of cancer progression. Here, we investigated the possible role of miR-144 in non-small cell lung cancer (NSCLC) development.

Material and methods:
The expression of miR-144 and TLR2 in NSCLC tissue and cell lines was determined by quantitative real-time PCR (qPCR). The TargetScan database was used to predict potential target genes of miR-144. Luciferase assay was used to verify the interaction between TLR2 and miR-144. TLR2 protein expression was measured by western blot. The secretion of interleukin (IL)-1β, IL-6 and IL-8 in A549 cells was detected by an ELISA kit. Cell migration and invasion were evaluated by wound healing assay and transwell assay, respectively.

Our results showed that miR-144 was downregulated in NSCLC tissue and cell lines when compared with the normal tissues and cell line (p < 0.05). The protein level of TLR2 in NSCLC tissue and cell lines was significantly higher than that in normal lung tissues. Dual luciferase reporter gene assay showed that miR-144 could bind to the 3ʹUTR of TLR2 specifically. Up-regulation of miR-144 significantly decreased the expression of TLR2. Up-regulation of miR-144 or down-regulation of TLR2 could decrease cell migration, invasion and secretion of IL-1β, IL-6 and IL-8 in A549 cells. Moreover, overexpression of TLR2 rescued the inhibitory effects of miR-144 on migration, invasion and inflammatory factor secretion of A549 cells.

miR-144 could inhibit the migration, invasion and secretion of IL-1β, IL-6 and IL-8 through downregulation of TLR2 expression in A549 cells.