407026

MIR29C

microRNA 29c;MIR29C;microRNA 29c

hsa-mir-29c

1q32.2

ncRNA

Our pilot study using miRNA arrays found that miRNA-29c (miR-29c) is differentially expressed in the paired low-metastatic lung cancer cell line 95C compared to the high-metastatic lung cancer cell line 95D. Bioinformatics analysis shows that integrin beta1 and matrix metalloproteinase 2 (MMP2) could be important target genes of miR-29c. Therefore, we hypothesized that miR-29c suppresses lung cancer cell adhesion to extracellular matrix (ECM) and metastasis by targeting integrin beta1 and MMP2. The gain-of-function studies that raised miR-29c expression in 95D cells by using its mimics showed reductions in cell proliferation, adhesion to ECM, invasion and migration. In contrasts, loss-of-function studies that reduced miR-29c by using its inhibitor in 95C cells promoted proliferation, adhesion to ECM, invasion and migration. Furthermore, the dual-luciferase reporter assay demonstrated that miR-29c inhibited the expression of the luciferase gene containing the 3-UTRs of integrin beta1 and MMP2 mRNA. Western blotting indicated that miR-29c downregulated the expression of integrin beta1 and MMP2 at the protein level. Gelatin zymography analysis further confirmed that miR-29c decreased MMP2 enzyme activity. Nude mice with xenograft models of lung cancer cells confirmed that miR-29c inhibited lung cancer metastasis in vivo, including bone and liver metastasis. Taken together, our results demonstrate that miR-29c serves as a tumor metastasis suppressor, which suppresses lung cancer cell adhesion to ECM and metastasis by directly inhibiting integrin beta1 and MMP2 expression and by further reducing MMP2 enzyme activity. The results show that miR-29c may be a novel therapeutic candidate target to slow lung cancer metastasis.

Using highly sensitive microarray-based procedures, we identified eight microRNAs (miRNAs) showing robust differential expression between 31 laser-capture-microdissected nasopharyngeal carcinomas (NPCs) and 10 normal healthy nasopharyngeal epithelial samples. In particular, miRNA mir-29c was expressed at one-fifth the levels in tumors as in normal epithelium. In NPC tumors, the lower mir-29c levels correlated with higher levels of multiple mRNAs whose 3' UTRs can bind mir-29c at target sequences conserved across many vertebrates. In cultured cells, introduction of mir-29c down-regulated these genes at the level of mRNA and inhibited expression of luciferase encoded by vectors having the 3' UTRs of these genes. Moreover, for each of several genes tested, mutating the mir-29c target sites in the 3' UTR abrogated mir-29c-induced inhibition of luciferase expression. Most of the mir-29c-targeted genes identified encode extracellular matrix proteins, including multiple collagens and laminin gamma1, that are associated with tumor cell invasiveness and metastatic potential, prominent characteristics of NPC. Thus, we identify eight miRNAs differentially expressed in NPC and demonstrate the involvement of one in regulating genes involved in metastasis.

Based on microarray analysis, we previously reported that miR-29c is significantly downregulated in nasopharyngeal carcinoma (NPC). However, little is known about the effect and molecular mechanisms of action of miR-29c deregulation during the development and progression of NPC. Quantitative RT-PCR demonstrated that miR-29c was significantly downregulated in NPC cell lines and clinical specimens. Wound healing, Transwell migration and lung metastasis assays demonstrated that ectopic expression of miR-29c inhibited NPC cell migration and invasion in vitro and suppressed the formation of lung metastases in vivo. T cell lymphoma invasion and metastasis 1 (TIAM1) was confirmed as a miR-29c target gene using luciferase reporter assays, quantitative RT-PCR and Western blotting. Ectopic expression of TIAM1 significantly promoted the migration and invasion of SUNE-1 cell line stably overexpressing miR-29c. The prognostic value of TIAM1 was analyzed in 217 NPC patients using immunohistochemistry. Strikingly, patients with high TIAM1 expression had poorer overall, disease-free and distant metastasis-free survival than patients with low TIAM1 expression. Furthermore, multivariate Cox regression analysis revealed that TIAM1 could serve as an independent prognostic factor in NPC. The newly identified miR-29c/TIAM1 pathway further elucidates the molecular mechanisms regulating invasion and metastasis in NPC, and may provide novel prognostic and treatment strategies for NPC patients.