Identification of microRNA-214 as a negative regulator of colorectal cancer liver metastasis by way of regulation of fibroblast growth factor receptor 1 expression.

The purpose of this study was to identify microRNAs (miRNAs) involved in the pathology of colorectal cancer (CRC) liver metastasis and investigate their underlying mechanisms. A total of 39 miRNAs were identified to be differentially expressed between 16 primary CRC tissues with liver metastases and 16 CRC tissues without liver metastases from 32 patients by Affymetric miRNA microarrays. A panel of eight miRNAs were confirmed to be significantly and differentially expressed between CRC tissues with and without liver metastases through quantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis in the 32 patients. In a validated cohort of 99 CRC patients (44 with and 55 without liver metastases), only miR-214 was validated to be significantly down-regulated in CRC with liver metastases, which was associated with an unfavorable prognosis. Ectopic expression of miR-214 suppressed proliferation, migration, and invasion in vitro, tumor growth and liver metastasis in an in vivo xenograft mouse model, whereas miR-214 knockdown promoted proliferation, migration, and invasion in CRC cell lines. Further studies indicated that fibroblast growth factor receptor 1 (FGFR1) was a potential target of miR-214. Restoring miR-214 expression in CRC cells decreased endogenous FGFR1 messenger RNA (mRNA) and protein levels. FGFR1 knockdown mimicked the tumor suppressive effect of miR-214 on CRC cells, while reintroduction of FGFR1 abolished the tumor suppressive effect of miR-214 on CRC cells. Moreover, miR-214 expression levels were inversely correlated with FGFR1 in CRC patients. Down-regulation of miR-214 expression was correlated with increased FGFR1 expression levels, which may contribute to increased CRC liver metastasis. miR-214 may serve as a potential marker to predict survival, and the miR-214-FGFR1 axis may be a therapeutic target in CRC patients.

Chen DL ，Wang ZQ ，Zeng ZL ，Wu WJ ，Zhang DS ，Luo HY ，Wang F ，Qiu MZ ，Wang DS ，Ren C ，Wang FH ，Chiao LJ ，Pelicano H ，Huang P ，Li YH ，Xu RH ... -  《-》

Genetic and epigenetic down-regulation of microRNA-212 promotes colorectal tumor metastasis via dysregulation of MnSOD.

Altered functions of microRNAs (miRNAs) have been associated with colorectal cancer (CRC). miR-212 is transcribed from a stable intron of a non-protein coding gene, and is reportedly down-regulated in different tumor types. We investigated the role of miR-212 in colorectal carcinogenesis and progression. We analyzed the expression of miR-212 by real-time polymerase chain reaction (PCR) analysis of colorectal cell lines and 180 paired tumor samples and surrounding healthy tissue. We overexpressed and knocked down miR-212 in CRC cell lines and assessed the in vitro effects. We also studied the effects of miR-212 overexpression on metastasis of tumors grown from HCT116 cells in nude mice. Overexpression of miR-212 inhibited CRC cell migration and invasion in vitro and formation of intrahepatic and pulmonary metastasis in vivo. We identified manganese superoxide dismutase (MnSOD) messenger RNA as a direct target of miR-212, and observed an inverse correlation between the level of miR-212 and MnSOD protein in colorectal tumor samples. MnSOD was required for down-regulation of epithelial markers and up-regulation of mesenchymal markers in CRC cells, indicating that it promoted the epithelial-mesenchymal transition. Overexpression of miR-212 reduced the levels of MnSOD to block the epithelial-mesenchymal transition process. Loss of heterozygosity and promoter hypermethylation each contributed to the down-regulation of miR-212. Reduced levels of miR-212 were associated with a more aggressive tumor phenotype and short disease-free survival times of patients (P = .0045; overall survival, P = .0015). miR-212 is down-regulated in human CRC tissues via genetic and epigenetic mechanisms. miR-212 might prevent tumor progression by targeting MnSOD messenger RNA; reduction of miR-212 could be a prognostic marker for patients with CRC. miR-212 and MnSOD might also be therapeutic targets for cancer.

Meng X ，Wu J ，Pan C ，Wang H ，Ying X ，Zhou Y ，Yu H ，Zuo Y ，Pan Z ，Liu RY ，Huang W ... -  《-》

MicroRNA-221 promotes colorectal cancer cell invasion and metastasis by targeting RECK.

MicroRNAs (miRNAs) have recently emerged as regulators of metastasis. We provide insight into the behavior of miR-221 in colorectal cancer (CRC) metastasis by showing that miR-221 is significantly upregulated in metastatic CRC cell lines and tissues. miR-221 overexpression enhances, whereas miR-221 depletion reduces CRC cell migration and invasion in vitro and metastasis in vivo. We identify RECK as a direct target of miR-221, reveal its expression to be inversely correlated with miR-221 in CRC samples and show that its re-introduction reverses miR-221-induced CRC invasiveness. Collectively, miR-221 is an oncogenic miRNA which may regulate CRC migration and invasion through targeting RECK.

Qin J ，Luo M 《-》

Decreased expression of microRNA-625 is associated with tumor metastasis and poor prognosis in patients with colorectal cancer.

MicroRNAs (miRNAs) play an essential role in colorectal cancer (CRC) development and progression. Aberrant miR-625 expression has been reported in several cancers. However, the clinical significance of miR-625 in human CRC has not been addressed. miR-625 expression was determined in 96 pairs of primary CRC and their corresponding adjacent nontumor tissues by quantitative reverse transcriptase-polymerase chain reaction. Associations of miR-625 expression with demographic and clinicopathologic features were determined. Additionally, the effects of ectopic expression of miR-625 on cell migration and invasion were investigated in vitro and in vivo. miR-625 was significantly downregulated in CRC tissues and cell lines. In addition, the decreased expression of miR-625 was positively associated with advanced lymph node metastasis (P = 0.038), liver metastasis (P = 0.031), poor overall survival (P = 0.002), and an unfavorable prognosis for CRC patients, as determined through a multivariate analysis (P = 0.034). Moreover, functional assays demonstrated that ectopic miR-625 expression inhibits the invasion and migration of HCT116 CRC cells both in vitro and in vivo. Our results suggest that miR-625 may serve as an efficient clinical biomarker and a therapeutic tool for the inhibition of metastasis in CRC.

Lou X ，Qi X ，Zhang Y ，Long H ，Yang J ... -  《-》

MicroRNA-137, an HMGA1 target, suppresses colorectal cancer cell invasion and metastasis in mice by directly targeting FMNL2.

Formin-like (FMNL)2 is up-regulated in colorectal tumors and has been associated with tumor progression, but little is known about regulatory mechanisms. We investigated whether microRNAs regulate levels of FMNL2 in colorectal cancer (CRC) cells. We used real-time polymerase chain reaction and immunoblot analyses to measure levels of miR-137, high-mobility group AT-hook (HMGA)1, and FMNL2 in CRC cells and tissue samples from patients (n = 50). We used luciferase reporter assays to determine the association between miR-137 and the FMNL2 3' untranslated region, and HMGA1 and the miR-137 promoter. Chromatin immunoprecipitation assays were used to assess direct binding of HMGA1 to the miR-137 promoter. miR-137 and miR-142-3p were predicted to bind FMNL2 based on bioinformatic data. Only the level of miR-137 had a significant inverse correlation with the level of FMNL2 protein in CRC cell lines and tissues. FMNL2 messenger RNA was targeted by miR-137; expression of miR-137 inhibited proliferation and invasion by CRC cells in vitro, and metastasis to liver and intestine by CRC xenografts in nude mice. HMGA1 bound to the promoter of miR-137 and activated its transcription, which reduced levels of FMNL2 in CRC cells. Ectopic expression of miR-137 in CRC cells inhibited phosphorylation of mitogen-activated protein kinase (MAPK) and Akt, which reduced levels of matrix metalloproteinase 2, matrix metalloproteinase 9, and vascular endothelial growth factor; it also reduced invasiveness of CRC cells, inhibiting signaling via phosphatidylinositol-4,5-bisphosphate 3-kinase, Akt, and MAPK. Levels of miR-137 and HMGA1 are reduced, and levels of FMNL2 are increased, in CRC samples compared with adjacent normal mucosa. In CRC cells, miR-137 targets FMNL2 messenger RNA and is regulated by the transcription factor HMGA1. Expression of miR-137 reduces CRC cell invasion in vitro and metastasis of tumor xenografts in mice. FMNL2 appears to activate phosphatidylinositol-4,5-bisphosphate 3-kinase, protein kinase B (Akt), and MAPK signaling pathways.

Liang L ，Li X ，Zhang X ，Lv Z ，He G ，Zhao W ，Ren X ，Li Y ，Bian X ，Liao W ，Liu W ，Yang G ，Ding Y ... -  《-》