Regulation of colorectal carcinoma stemness, growth, and metastasis by an miR-200c-Sox2-negative feedback loop mechanism.

To elucidate a novel mechanism of miR-200c in the regulation of stemness, growth, and metastasis in colorectal carcinoma (CRC). Quantitative reverse transcription PCR was used to quantify miR-200c expression in CRC cell lines and tissues. A luciferase assay was adopted for the target evaluation. The functional effects of miR-200c in CRC cells were assessed by its forced or inhibited expression using lentiviruses. MiR-200c was statistically lower in CRC clinical specimens and highly metastatic CRC cell lines compared with their counterparts. Sox2 was validated as a target for miR-200c. The knockdown of miR-200c significantly enhanced proliferation, migration, and invasion in CRC cell lines, whereas the upregulation of miR-200c exhibited an inverse effect. Moreover, rescue of Sox2 expression could abolish the effect of the upregulation of miR-200c. In addition, the reduction of miR-200c increased the expression of CRC stem cell markers and the sphere-forming capacity of CRC cell lines. Further study has shown that miR-200c and Sox2 reciprocally control their expression through a feedback loop. MiR-200c suppresses the expression of Sox2 to block the activity of the phosphoinositide 3-kinase (PI3K)-AKT pathway. Our findings indicate that miR-200c regulates Sox2 expression through a feedback loop and is associated with CRC stemness, growth, and metastasis.

Lu YX ，Yuan L ，Xue XL ，Zhou M ，Liu Y ，Zhang C ，Li JP ，Zheng L ，Hong M ，Li XN ... -  《-》

miR-133a represses tumour growth and metastasis in colorectal cancer by targeting LIM and SH3 protein 1 and inhibiting the MAPK pathway.

In recent studies of microRNA expression, miR-133a deregulation was identified in colorectal carcinoma (CRC). However, the mechanisms underlying the pathogenesis and progression of CRC are poorly understood. We found that miR-133a expression was usually down-regulated in CRC cell lines and tissue specimens. Ectopic miR-133a expression inhibited cell proliferation and cell migration. Stable overexpression of miR-133a was sufficient to suppress tumour growth and intrahepatic and pulmonary metastasis in vivo. Additional studies showed that miR-133a can target the 3' untranslated region (3'UTR) of LIM and SH3 protein 1 (LASP1) mRNA and suppress the expression of LASP1, which we identified in previous studies as a CRC-associated protein. In contrast to the phenotypes induced by miR-133a restoration, LASP1-induced cell proliferation and migration rescued miR-133a-mediated biological behaviours, as did LASP1 overexpression. Investigations of possible mechanisms underlying these behaviours revealed that miR-133a modulates the expression of key cellular molecules and participates in the MAPK pathway by inhibiting phosphorylation of ERK and MEK. miR-133a may play a key role in CRC genesis and metastasis, which suggests its potential role in the molecular therapy of cancer.

Wang H ，An H ，Wang B ，Liao Q ，Li W ，Jin X ，Cui S ，Zhang Y ，Ding Y ，Zhao L ... -  《-》

The SOX17/miR-371-5p/SOX2 axis inhibits EMT, stem cell properties and metastasis in colorectal cancer.

Li Y ，Lv Z ，He G ，Wang J ，Zhang X ，Lu G ，Ren X ，Wang F ，Zhu X ，Ding Y ，Liao W ，Ding Y ，Liang L ... -  《Oncotarget》

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 ... -  《-》

MicroRNA-375 inhibits colorectal cancer growth by targeting PIK3CA.

Colorectal cancer (CRC) is the second most common cause of death from cancer. MicroRNAs (miRNAs) represent a class of small non-coding RNAs that control gene expression by triggering RNA degradation or interfering with translation. Aberrant miRNA expression is involved in human disease including cancer. Herein, we showed that miR-375 was frequently down-regulated in human colorectal cancer cell lines and tissues when compared to normal human colon tissues. PIK3CA was identified as a potential miR-375 target by bioinformatics. Overexpression of miR-375 in SW480 and HCT15 cells reduced PIK3CA protein expression. Subsequently, using reporter constructs, we showed that the PIK3CA untranslated region (3'-UTR) carries the directly binding site of miR-375. Additionally, miR-375 suppressed CRC cell proliferation and colony formation and led to cell cycle arrest. Furthermore, miR-375 overexpression resulted in inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. SiRNA-mediated silencing of PIK3CA blocked the inhibitory effect of miR-375 on CRC cell growth. Lastly, we found overexpressed miR-375 effectively repressed tumor growth in xenograft animal experiments. Taken together, we propose that overexpression of miR-375 may provide a selective growth inhibition for CRC cells by targeting PI3K/Akt signaling pathway.

Wang Y ，Tang Q ，Li M ，Jiang S ，Wang X ... -  《-》