MiR-346-5p promotes colorectal cancer cell proliferation in vitro and in vivo by targeting FBXL2 and activating the β-catenin signaling pathway.

MiR-346-5p is overexpressed in several cancers, including colorectal cancer (CRC). However, the effects of miR-346-5p on CRC progression have not yet been clarified. In our study, miR-346-5p levels in four CRC cell lines and normal human colon epithelial cells were determined by real-time PCR. SW620 and HCT116 cells were selected and then transfected with miR-346-5p mimic, miR-346-5p inhibitor, or specific siRNAs targeting F-box/LRR-repeat protein 2 (FBXL2). Cell proliferation, cell cycle distribution and cell cycle regulators were examined by CCK-8 assay, flow cytometry, and western blot. The binding of miR-346-5p on 3' untranslated region (UTR) of FBXL2 were verified by dual-luciferase reporter assay. CRC cells were co-transfected with miR-346-5p inhibitor and siFBXL2 to investigate the involvement of FBXL2. Interaction of FBXL2 with forkhead box M1 (FoxM1) was examined by co-immunoprecipitation (Co-IP) assay. The effect of miR-346-5p knockdown on CRC tumorigenesis in vivo was investigated. Here, we found that miR-346-5p overexpression promoted, while miR-346-5p knockdown inhibited cell proliferation and G1-S transition. Inhibition of FBXL2 showed similar effects as miR-346-5p overexpression. Moreover, we verified that FBXL2 was a direct target of miR-346-5p. FBXL2 interacted with FoxM1, and then negatively regulated both FoxM1 and nuclear β-catenin levels. Additionally, FBXL2 knockdown reversed the effects of miR-346-5p inhibitor. In xenograft models, miR-346-5p knockdown significantly inhibited tumor growth, increased FBXL2 expression, and downregulated the levels of FoxM1 and nuclear β-catenin. In conclusion, miR-346-5p may promote CRC growth by targeting FBXL2 and activating the β-catenin signaling pathway. MiR-346-5p may be a novel target in cancer therapy.

Pan S ，Wu W ，Ren F ，Li L ，Li Y ，Li W ，Wang A ，Liu D ，Dong Y ... -  《-》

Dysregulation of miR-6868-5p/FOXM1 circuit contributes to colorectal cancer angiogenesis.

Wang Y ，Wu M ，Lei Z ，Huang M ，Li Z ，Wang L ，Cao Q ，Han D ，Chang Y ，Chen Y ，Liu X ，Xue L ，Mao X ，Geng J ，Chen Y ，Dai T ，Ren L ，Wang Q ，Yu H ，Chen C ，Chu X ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

microRNA-7 is a novel inhibitor of YY1 contributing to colorectal tumorigenesis.

Zhang N ，Li X ，Wu CW ，Dong Y ，Cai M ，Mok MT ，Wang H ，Chen J ，Ng SS ，Chen M ，Sung JJ ，Yu J ... -  《-》

TRIB3 Interacts With β-Catenin and TCF4 to Increase Stem Cell Features of Colorectal Cancer Stem Cells and Tumorigenesis.

Activation of Wnt signaling to β-catenin contributes to the development of colorectal cancer (CRC). Expression of tribbles pseudo-kinase 3 (TRIB3) is increased in some colorectal tumors and associated with poor outcome. We investigated whether increased TRIB3 expression promotes stem cell features of CRC cells and tumor progression by interacting with the Wnt signaling pathway. We performed studies with C57BL/6J-ApcMin/J mice injected with an adeno-associated virus vector that expresses a small hairpin RNA against Trib3 mRNA (ApcMin/J-Trib3KD) or a control vector (ApcMin/J-Ctrl). We created BALB/c mice that overexpress TRIB3 from an adeno-associated virus vector and mice with small hairpin RNA-mediated knockdown of β-catenin. The mice were given azoxymethane followed by dextran sodium sulfate to induce colitis-associated cancer. Intestinal tissues were collected and analyzed by histology, gene expression profiling, immunohistochemistry, and immunofluorescence. Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5)-positive (LGR5Pos) and LGR5-negative (LGR5Neg) HCT-8 CRC cells, with or without knockdown or transgenic expression of TRIB3, were sorted and analyzed in sphere-formation assays. We derived organoids from human and mouse colorectal tumors to analyze the function of TRIB3 and test the effect of a peptide inhibitor. Wnt signaling to β-catenin was analyzed in dual luciferase reporter, chromatin precipitation, immunofluorescence, and immunoblot assays. Proteins that interact with TRIB3 were identified by immunoprecipitation. CRC cell lines were grown in nude mice as xenograft tumors. At 10 weeks of age, more than half the ApcMin/J-Ctrl mice developed intestinal high-grade epithelial neoplasia, whereas ApcMin/J-Trib3KD mice had no intestinal polyps and normal histology. Colon tissues from ApcMin/J-Trib3KD mice expressed lower levels of genes regulated by β-catenin and genes associated with cancer stem cells. Mice with overexpression of Trib3 developed more tumors after administration of azoxymethane and dextran sodium sulfate than BALB/c mice. Mice with knockdown of β-catenin had a lower tumor burden after administration of azoxymethane and dextran sodium sulfate, regardless of Trib3 overexpression. Intestinal tissues from mice with overexpression of Trib3 and knockdown of β-catenin did not have activation of Wnt signaling or expression of genes regulated by β-catenin. LGR5Pos cells sorted from HCT-8 cells expressed higher levels of TRIB3 than LGR5Neg cells. CRC cells that overexpressed TRIB3 had higher levels of transcription by β-catenin and formed larger spheroids than control CRC cells; knockdown of β-catenin prevented the larger organoid size caused by TRIB3 overexpression. TRIB3 interacted physically with β-catenin and transcription factor 4 (TCF4). TRIB3 overexpression increased, and TRIB3 knockdown decreased, recruitment of TCF4 and β-catenin to the promoter region of genes regulated by Wnt. Activated β-catenin increased expression of TRIB3, indicating a positive-feedback loop. A peptide (P2-T3A6) that bound β-catenin disrupted its interaction with TRIB3 and TCF4. In primary CRC cells and HCT-8 cells, P2-T3A6 decreased expression of genes regulated by β-catenin and genes associated with cancer stem cells and decreased cell viability and migration. Injection of C57BL/6J-ApcMin/J mice with P2-T3A6 decreased the number and size of tumor nodules and colon expression of genes regulated by β-catenin. P2-T3A6 increased 5-fluorouracil-induced death of CRC cells and survival times of mice with xenograft tumors. TRIB3 interacts with β-catenin and TCF4 in intestine cells to increase expression of genes associated with cancer stem cells. Knockdown of TRIB3 decreases colon neoplasia in mice, migration of CRC cells, and their growth as xenograft tumors in mice. Strategies to block TRIB3 activity might be developed for treatment of CRC.

Hua F ，Shang S ，Yang YW ，Zhang HZ ，Xu TL ，Yu JJ ，Zhou DD ，Cui B ，Li K ，Lv XX ，Zhang XW ，Liu SS ，Yu JM ，Wang F ，Zhang C ，Huang B ，Hu ZW ... -  《-》

miR-140-5p is negatively correlated with proliferation, invasion, and tumorigenesis in malignant melanoma by targeting SOX4 via the Wnt/β-catenin and NF-κB cascades.

MicroRNAs (miRNAs) have been validated as critical regulators in the development of melanoma. miR-140 was abnormally downregulated in uveal melanoma samples. However, the expression level and roles of miR-140-5p remain unclear in melanoma for now. We speculate that miR-140-5p is abnormally expressed and may play an important role in melanoma. The expressions of miR-140-5p and SOX4 messenger RNA were determined by quantitative real-time polymerase chain reaction assays. Western blot assays were employed to detect the expression levels of SOX4, Ki67, MMP-2, MMP-7, p-β-catenin, c-Myc, cyclin D1, p65, and IκBα. Luciferase reporter assays were employed to elucidate the interaction between SOX4 and miR-140-5p. MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) and transwell invasion assays were applied to evaluate capabilities of cell proliferation and invasion, respectively. Xenograft models of melanoma were established to verify the role and molecular basis of miR-140-5p. Immunohistochemical (IHC) assays were employed to measure the Ki67 and SOX4 at the protein level in xenografted melanoma tissues. Herein, these observations showed that, miR-140-5p was abnormally downregulated in melanoma tissues and cells, while SOX4 was upregulated. miR-140-5p directly targeted SOX4 and inhibited its expression in melanoma cells. miR-140-5p overexpression repressed melanoma cell proliferation and invasion and its effects were partially restored SOX4 overexpression. Moreover, miR-140-5p hindered melanoma growth in vivo by downregulating SOX4. Mechanistically, miR-140-5p suppressed activation of the Wnt/β-catenin and NF-κB pathways by targeting SOX4. Our study concluded that miR-140-5p hindered cell proliferation, invasion, and tumorigenesis by targeting SOX4 via inactivation of the Wnt/β-catenin and NF-κB signaling pathways in malignant melanoma, which provides an underlying molecular mechanism for the treatment for melanoma with miRNAs.

Zhao G ，Yin Y ，Zhao B 《-》