MicroRNA-29b attenuates non-small cell lung cancer metastasis by targeting matrix metalloproteinase 2 and PTEN

Background: our pilot study using mirna pcr array found that mirna-29b (mir-29b) is differentially expressed in primary cultured cd133-positive a549 cells compared with cd133-negative a549 cells. methods: ten human non-small cell lung cancer (nsclc) cell lines and samples from thirty patients with nsclc were analyzed for the expression of mir-29b by quantitative rt-pcr. bioinformatics analysis combined with tumor metastasis pcr array showed the potential target genes for mir-29b. mir-29b lentivirus and inhibitors were transfected into nsclc cells to investigate its role on regulating cell proliferation which was measured by cck-8 assay in vitro and nude mice xenograft tumor assay in vivo. cell motility ability was evaluated by transwell assay. the target genes of mir-29b were determined by luciferase assay,quantitative rt-pcr and western blot. results: bioinformatics analysis combined with tumor metastasis pcr array showed that matrix metalloproteinase 2 (mmp2) and pten could be important target genes of mir-29b. the expression of mir-29b was down regulated in nsclc tissues compared to the normal tissues. clinicopathological analysis demonstrated that mir-29b had significant negative correlation with lymphatic metastasis. the gain-of-function studies revealed that ectopic expression of mir-29b decreased cell proliferation,migration and invasion abilities of nsclc cells. in contrasts,loss-of-function studies showed that inhibition of mir-29b promoted cell proliferation,migration and invasion of nsclc cells in vitro. nude mice xenograft tumor assay confirmed that mir-29b inhibited lung cancer growth in vivo. high-invasion (a549-h) and low-invasion (a549-l) nsclc cell sublines from a549 cells were created by using the repeated transwell assay aimed to confirm the effect of mir-29b on migration and invasion of nsclc. furthermore,the dual-luciferase reporter assay demonstrated that mir-29b inhibited the expression of the luciferase gene containing the 3'-utrs of mmp2 and pten mrna. western blotting and quantitative rt-pcr indicated that mir-29b down-regulated the expression of mmp2 at the protein and mrna levels. conclusion: taken together,our results demonstrate that mir-29b serves as a tumor metastasis suppressor,which suppresses nsclc cell metastasis by directly inhibiting mmp2 expression. the results show that mir-29b may be a novel therapeutic candidate target to slow nsclc metastasis. © 2015 wang et al.