Abstract
BackgroundOur previous studies showed that SIRT1 was over-expressed in gastric cancer specimens and related with lymph node metastasis. However, the mechanism of SIRT1 up-regulation and its association with metastasis in gastric cancer remain unclear. The present study was undertaken to understand the role of microRNA in regulation of SIRT1 in the progression of gastric cancer.MethodsExpression of miR-204 and SIRT1 was assessed in two gastric cancer cell lines and 24 matched cancer specimens. Luciferase reporter assay was carried to verify that miR-204 targeting SIRT1. Cell invasion ability of AGS and BGC was detected by transwell invasion assay. Annexin V/PI assay was used to investigate the cell sensitivity of anoikis. Western blot analysis to assess SIRT1, Vimentin, E-Cadherin, LKB1, and β-actin expression was performed in gastic cancer cell lines.ResultsSIRT1 was defined as the target gene and elucidated the biological functions of miR-204 with a luciferase reporter assay and Western blot analysis. We verified that miR-204 levels were down-regulated and significantly associated with the up-regulation of SIRT1 mRNA levels in gastric cancer specimens. Over-expression of miR-204 reduced cell invasion and anoikis resistance in gastric cancer cells. Up-regulation of miR-204 influenced the levels of the epithelial mesenchymal transition (EMT)-associated genes, increasing E-cadherin levels and decreasing Vimentin levels. We demonstrated that the regulation of EMT by miR-204 involves cooperation with LKB1. Furthermore, silencing of SIRT1 phenocopied the effects of miR-204 in gastric cancer cells. These data demonstrate that miR-204 plays an important role in regulating metastasis of gastric cancer, which is involved in post-transcriptional repression of SIRT1.ConclusionOur results suggest that down-regulation of miR-204 promotes gastric cancer cell invasion by activating the SIRT1-LKB1 pathway. These data demonstrate that miR-204 plays an important role in regulating metastasis of gastric cancer, which is involved in post-transcriptional repression of SIRT1.
Highlights
Our previous studies showed that SIRT1 was over-expressed in gastric cancer specimens and related with lymph node metastasis
Increasing evidence suggests that post-transcriptional regulation of gene expression, which is mediated by microRNAs, controls tumorigenesis and cancer metastasis [7,8,9]
Expression of miR-204 is significantly down-regulated in gastric cancer and associated with cancer metastasis The expression of all miRNAs conserved across various species and predicted to target SIRT1 through bioinformatics was evaluated
Summary
Our previous studies showed that SIRT1 was over-expressed in gastric cancer specimens and related with lymph node metastasis. Increasing evidence suggests that post-transcriptional regulation of gene expression, which is mediated by microRNAs (miRNAs), controls tumorigenesis and cancer metastasis [7,8,9]. Adam et al demonstrated that miR-200 regulated EMT in bladder cancer cells and reversed resistance to epidermal growth factor receptor (EGFR) therapy [7]. This group showed that the stable expression of miR-200 in mesenchymal UMUC3 cells increased E-cadherin levels; decreased protein expression of ZEB1, ZEB2, and ERRFI-1; decreased cell migration; and increased sensitivity to EGFR-blocking agents. Decreased miR-218 levels eliminated Robo repression, which activated the Slit-Robo pathway through the interaction between Robo and Slit to trigger tumor metastasis [10]
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