407000

MIR218-1

MIRN218-1|mir-218-1;microRNA 218-1;MIR218-1;microRNA 218-1

hsa-mir-218-1

4p15.31

ncRNA

OBJECTIVE: To investigate the expression and function of miR-218 in gastric cancer. METHODS: miR-218 levels were evaluated in 20 non-cardia gastric cancer tissues using TaqMan stem-loop real-time PCR analysis. Pre-miR-218 and anti-miR-218 inhibitor were used to change the miR-218 expression level and examine its effects on cell proliferation, apoptosis, cell cycle and cell invasion. RESULTS: Comparing with the corresponding normal tissues, miR-218 expression was significantly reduced in the gastric cancer tissue (P < 0.01). Forced expression of miR-218 increased apoptosis in AGS cells. The proportion of apoptosis cells induced by transfection of pre-miR-218 was greater than that induced by control (21.6% vs. 10.4%, P = 0.032). Pre-miR-218 resulted in a significantly decreased cell growth activity (P < 0.01) and cell invasion (P < 0.05) of AGS cells compared with that of the control. CONCLUSION: miR-218 expression is reduced in gastric cancer. miR-218 may function as a tumor suppressor in gastric carcinoma.

Growing evidence suggests that microRNAs (miRNAs) are aberrantly expressed in many human cancers, and that they play significant roles in carcinogenesis and cancer progression. The identification of tumor suppressive miRNAs and their target genes could provide new insights into the mechanism of carcinogenesis. However, the genetic or epigenetic regulations of these miRNAs have not yet been fully elucidated in bladder cancer (BC). Chromosomal alterations of cancer cells give us important information for the identification of tumor suppressor genes. Our miRNA array-comparative genomic hybridization (CGH) analysis showed several miRNAs to be candidate tumor suppressors of BC. Our array-CGH analysis revealed that chromosome 4 was lost in all BC cell lines. We selected 19 miRNAs located on chromosome 4 and evaluated their expression levels in cancer cell lines as well as clinical samples. Gain-of-function analysis revealed that miR-218 inhibited BC cell proliferation, migration and invasion. Furthermore, flow cytometry analysis showed that it induced BC cell apoptosis. Genome-wide gene expression analysis showed that it targeted multiple oncogenes in BC. Our study is the first to demonstrate that miR-218 located on chrosomosme 4p15.31 is a tumor suppressive miRNA in BC. The identification of tumor suppressive miRNAs and their target genes on the basis of array-CGH analysis could provide new insights into the mechanisms of BC carcinogenesis.

Our recent studies of the microRNA (miRNA) expression signature in prostate cancer (PCa) indicated that miRNA-218 (miR-218) was significantly downregulated in clinical specimens, suggesting that miR-218 might act as a tumor-suppressive miRNA in PCa. The aim of the present study was to investigate the functional significance of miR-218 in PCa and to identify novel miR-218-regulated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR-218 in PCa cell lines (PC3 and DU145) revealed that this miRNA significantly inhibited cancer cell migration and invasion. gene expression data and in silico analysis demonstrated that LIM and SH3 protein 1 (LASP1) is a potential target of miR-218 regulation. LASP1 is a cytoskeletal scaffold protein that plays critical roles in cytoskeletal organization and cell migration. Luciferase reporter assays showed that miR-218 directly regulated expression of LASP1. Moreover, downregulating the LASP1 gene significantly inhibited cell migration and invasion in cancer cells, and the expression of LASP1 was upregulated in cancer tissues. We conclude that loss of tumor-suppressive miR-218 enhanced cancer cell migration and invasion in PCa through direct regulation of LASP1. Our data on pathways regulated by tumor-suppressive miR-218 provide new insight into the potential mechanisms of PCa oncogenesis and metastasis.