miR-155 regulates the proliferation and cell cycle of colorectal carcinoma cells by targeting E2F2

MicroRNAs play important roles in carcinogenesis by negatively regulating the expression of target genes. Here we explore the biological function of miR-155 and the underlying mechanism in colorectal carcinoma. We validate, for the first time, that E2F2 is a direct target of miR-155 using western blot and a luciferase reporter assay and that miR-155 regulates the proliferation and cell cycle of colorectal carcinoma cells by targeting E2F2 using siRNA technology. We also found, for the first, time that E2F2 acts as a tumor suppressor in colorectal carcinoma. Overall, miR-155 plays an important role in colorectal carcinoma tumorigenesis by negative regulation of its targets including E2F2 and may be a potential therapeutic target for colorectal carcinoma treatment.     

miR-223 regulates migration and invasion by targeting Artemin in human esophageal carcinoma

Background

Artemin (ARTN) is a neurotrophic factor belonging to the glial cell-derived neurotrophic factor family of ligands. To develop potential therapy targeting ARTN, we studied the roles of miR-223 in the migration and invasion of human esophageal carcinoma.

Methods

ARTN expression levels were detected in esophageal carcinoma cell lines KYSE-150, KYSE-510, EC-9706, TE13, esophageal cancer tissues and paired non-cancerous tissues by Western blot. Artemin siRNA expression vectors were constructed to knockdown of artemin expression mitigated migration and invasiveness in KYSE150 cells. Monolayer wound healing assay and Transwell invasion assay were applied to observe cancer cell migration and invasion. The relative levels of expression were quantified by real-time quantitative PCR.

Results

ARTN expression levels were higher in esophageal carcinoma tissue than in the adjacent tissue and was differentially expressed in various esophageal carcinoma cell lines. ARTN mRNA contains a binding site for miR-223 in the 3'UTR. Co-transfection of a mir-223 expression vector with pMIR-ARTN led to the reduced activity of luciferase in a dual-luciferase reporter gene assay, suggesting that ARTN is a target gene of miR-223. Overexpression of miR-223 decreased expression of ARTN in KYSE150 cells while silencing miR-223 increased expression of ARTN in EC9706 cells. Furthermore, overexpression of miR-223 in KYSE150 cells decreased cell migration and invasion. Silencing of miR-223 in EC9706 cells increased cell migration and invasiveness.

Conclusions

These results reveal that ARTN, a known tumor metastasis-related gene, is a direct target of miR-223 and that miR-223 may have a tumor suppressor function in esophageal carcinoma and could be used in anticancer therapies.     

miR-198 inhibits migration and invasion of hepatocellular carcinoma cells by targeting the HGF/c-MET pathway

Metastasis is the leading cause of death in patients with hepatocellular carcinoma (HCC) and microRNAs have been implicated to influence this process. Emerging evidence indicates that miR-198 is down-regulated in HCC compared to normal liver parenchyma, but the functional roles of miR-198 in HCC cells remains unexplored. Herein, we show that miR-198 directly targets c-MET via its 3'UTR. Forced expression of miR-198 decreased c-MET expression at both mRNA and protein levels and consequently diminished HGF induced phosphorylation of p44/42 MAPK in HCC cells. Forced expression of miR-198 inhibited HGF promotion of HCC cell migration and invasion in a c-MET dependent manner. In conclusion, we have identified miR-198 as a novel suppressor of HCC cell invasion by negative regulation of the HGF/c-MET pathway.     

miR-154 inhibits EMT by targeting HMGA2 in prostate cancer cells

Epithelial–mesenchymal transition (EMT) is a crucial process that plays an important role in the invasion and metastasis of human cancers. High-mobility group AT-hook 2 (HMGA2) has been found to be involved in the EMT program, with its aberrant expression having been observed in a variety of malignant tumors. However, the mechanisms regulating HMGA2 expression remain incompletely understood. The objective of this study was to investigate whether mir-154 plays a critical role in EMT by regulating HMGA2. The expression levels of HMGA2 were examined in four samples of prostate cancer (PCa) tissue and adjacent non-tumorous tissue by Western blot analysis. The effects of forced expression of miR-154 or HMGA2 knockdown on PCa cells were evaluated by cell migration and invasion assays and Western blot analysis. HMGA2 was upregulated in the PCa tissue samples compared with the adjacent normal ones. Forced expression of miR-154 or HMGA2 knockdown significantly reduced the migratory and invasive capabilities of PCa cells in vitro and inhibited EMT gene expression, increased the levels of E-cadherin, an epithelial marker, and decreased the levels of vimentin, a mesenchymal marker. HMGA2 is a direct target gene of miR-154 by dual-luciferase reporter assay. Our findings suggest that miR-154 plays a role in regulating EMT by targeting HMGA2. Understanding the targets and regulating pathways of miR-154 may provide new insights into the underlying pathogenesis of PCa.     

miR-154 suppresses colorectal cancer cell growth and motility by targeting TLR2

MicroRNAs play critical roles in the development and progression of colorectal cancer (CRC). miR-154 acts as a tumor suppressor in several tumors; however, its role in CRC is poorly understood. Herein, we found that miR-154 was decreased in CRC tissues and cell lines. Ectopic expression of miR-154 remarkably suppressed cell proliferation and colony formation, migration and invasion in CRC cells. The toll-like receptor 2 (TLR2) was found to be a direct target of miR-154 in CRC cells. Inhibition of TLR2 performed similar effects with miR-154 overexpression on CRC cells, and overexpression of TLR2 could significantly reverse the tumor suppressive effects of miR-154 on CRC cells. This study suggests an essential role for miR-154 in CRC.     

miR-29a suppresses growth and invasion of gastric cancer cells in vitro by targeting VEGF-A

Increasing data shows miR-29a is a key regulator of oncogenic processes. It is significantly down-regulated in some kind of human tumors and possibly functionally linked to cellular proliferation, survival and migration. However, the mechanism remains unclear. In this study, we report miR-29a is significantly under-expressed in gastric cancer compared to the healthy donor. The microvessel density is negatively related to miR-29a expression in gastric cancer tissues. The ectopic expression of miR-29a significantly inhibits proliferation and invasion of gastric cancer cells. Furthermore, western blot combined with the luciferase reporter assays demonstrate that vascular endothelial growth factor A (VEGF-A) is direct target of miR-29a. This is the first time miR-29a was found to suppress the tumor microvessel density in gastric cancer by targeting VEGF-A. Taken together, these results suggest that miR-29a is a tumor suppressor in gastric cancer. Restoration of miR-29a in gastric cancer may be a promising therapeutic approach. [BMB Reports 2014; 47(1):39-44]     

miR-206 inhibits thyroid cancer proliferation and invasion by targeting RAP1B

Thyroid cancer (TC) is one of the primary tumors arisen from endocrine system. The purpose of this study was to investigate the underlying mechanism by which RAP1B (Ras-related protein Rap-1b) modulates microRNA (miR)-206 related effects on TC cells. Expression of miR-206 and RAP1B was analyzed in cells and tissues. miR-206 mimics or inhibitors and RAP1B vector were used in functional experiments to investigate the effects of miR-206 and RAP1B on cell activities including proliferation, migration, and invasion. Luciferase assay was performed to explore the association between miR-206 and RAP1B. The influence of miR-206 on tumorigenesis of TC cells was investigated using an ex vivo model. Our results demonstrated the reduce of miR-206 in TC tissues and cell lines in which RAP1B was increased. Overexpression of miR-206 significantly inhibited the functional capacities of TPC-1 cells including proliferation, invasion, and migration, most likely, through reducing the expression of RAP1B. Xenograft experiment showed that increased miR-206 could effectively inhibit the tumorigenesis of TC cells. Our study showed that miR-206 negatively regulated cell activities of proliferation, invasion, and migration in TC via suppressing RAP1B expression, suggesting that miR-206 exerts a vital role in TC.     

Suppression of miR-221 inhibits glioma cells proliferation and invasion via targeting SEMA3B

Background

Gliomas are the most common primary tumors in the central nervous system. Due to complicated signaling pathways involved in glioma progression, effective targets for treatment and biomarkers for prognosis prediction are still scant.

Results

In this study we revealed that a new microRNA (miR), the miR-221, was highly expressed in the glioma cells, and suppression of miR-221 resulted in decreased cellular proliferation, migration, and invasion in glioma cells. Mechanistic experiments validated that miR-221 participates in regulating glioma cells proliferation and invasion via suppression of a direct target gene, the Semaphorin 3B (SEMA3B). The rescue experiment with miR-221 and SEMA3B both knockdown results in significant reversion of miR-221 induced phenotypes.

Conclusion

Taken together, our findings highlight an unappreciated role for miR-221 and SEMA3B in glioma.     

miR-217 inhibits invasion of hepatocellular carcinoma cells through direct suppression of E2F3

The poor prognosis of hepatocellular carcinoma (HCC) is mainly due to the development of invasion and metastasis. Recent data strongly suggests the important role of miRNAs in cancer progression, including invasion and metastasis. Here, we found miR-217 expression was much lower in highly invasive MHCC-97H HCC cells and metastatic HCC tissues. Restored miR-217 expression with miR-217 mimics inhibited invasion of MHCC-97H cells. Inversely, miR-217 inhibition enhanced the invasive ability of Huh7 and MHCC-97L cells. Mechanically, bioinformatics analysis combined with experimental analysis demonstrated E2F3 was a novel direct target of miR-217. Moreover, E2F3 protein level was positively associated with HCC metastasis and functional analysis confirmed the positive role of E2F3 in HCC cell invasion. Our findings suggest miR-217 function as a potential tumor suppressor in HCC progression and miR-217-E2F3 axis may be a novel candidate for developing rational therapeutic strategies.     

Differential expression of miR-195 in esophageal squamous cell carcinoma and miR-195 expression inhibits tumor cell proliferation and invasion by targeting of Cdc42

MicroRNAs (miRNA) have played an important role in carcinogenesis. In this study, Agilent miRNA microarray was used to identify differentially expressed miRNAs in esophageal squamous cell carcinoma (ESCC) tissues and miR-195 was downregulated in ESCC compared with normal esophageal tissues. Moreover, Cdc42 was confirmed as target gene of miR-195. Ectopic expression of miR-195 in ESCC cells significantly downregulated Cdc42 by directly binding its 3′ untranslated regions, and induced G1 cell cycle arrest, leading to a significant decrease in cell growth, migration, and invasion in vitro. Therefore, our findings demonstrated that miR-195 may act as a tumor suppressor in ESCC by targeting Cdc42.     

miR-335 suppresses migration and invasion by targeting ROCK1 in osteosarcoma cells

Dynamic remodeling of the actin cytoskeleton is crucial for biological processes such as cell migration and cell spreading. S100A10 is a member of the S100 protein family and is involved in intracellular trafficking and cell migration. In this study, we examined the role of S100A10 in actin cytoskeletal organization and cell spreading. Depletion of S100A10 induced disruption of stress fiber formation and delay in cell spreading. Rac1 activation during spreading was suppressed by S100A10 knockdown, and exogenous expression of active Rac1 restored the ability of cells to spread in the absence of S100A10. Our results demonstrate the crucial role of S100A10 in actin dynamics promoting cell spreading via Rac1 activation.     

miR-210 inhibits cell migration and invasion by targeting the brain-derived neurotrophic factor in glioblastoma

Recently, there is increasing evidence that microRNAs are related to the development, diagnosis, treatment, and prognosis of glioblastoma. microRNA-210 (miR-210) had been identified in many human cancers, but the specific function of miR-210 remains unclear in glioblastoma. The present study mainly focused on exploring its biological role and potential molecular mechanisms in glioblastoma. We found that miR-210 expression was decreased in glioblastoma, and downregulation of miR-210 was related to worse prognosis in glioblastoma patients. In addition, miR-210 overexpression inhibited the migration and invasion of human glioblastoma cells. At the same time, we found that miR-210 directly targets the brain-derived neurotrophic factor (BDNF) and reduces BDNF expression level. Consistently, BDNF silencing had the same effects as miR-210 overexpression in glioblastoma, and upregulation of BDNF counteracted the inhibitory effect of miR-210 in glioblastoma. In conclusion, miR-210 suppressed the migration and invasion of glioblastoma cells by targeting BDNF.     

miR-204-5p regulates cell proliferation,invasion, and apoptosis by targeting IL-11 in esophageal squamous cell carcinoma

Esophageal cancer (EC) is the world's eighth most common malignant neoplasm and is ranked as the sixth leading cause of death related to cancer. Aberrant microRNA (miRNA) expression has been reported to be associated with esophageal squamous cell carcinoma. However, the molecular mechanism of miR-204-5p in esophageal squamous cell carcinoma (ESCC) is not clear. Therefore, the aim of this study was to investigate the potential role of miR-204-5p in ESCC. In the present study, we found that miR-204-5p could affect ESCC proliferation, invasion, apoptosis, and cell cycle in cell and mouse models. A dual-luciferase reporter assay showed that miR-204-5p expression was negatively correlated with interleukin-11 (IL-11) expression. IL-11 overexpression reversed the suppressive effects of miR-204-5p in the cell lines. These results indicated that miR-204-5p functions as a tumor suppressor by directly targeting IL-11 in ESCC.     

miR-21 targets the tumor suppressor RhoB and regulates proliferation, invasion and apoptosis in colorectal cancer cells

It has become increasingly clear that microRNAs play an important role in many human diseases including cancer. Here, we show that expression of miR-21 in HEK293 and several colorectal cancer cells was found inversely correlated with ras homolog gene family, member B (RhoB) expression. miR-21 expression significantly suppressed RhoB 3' UTR luciferase-reporter activity, but the inhibitory effect was lost when the putative target sites were mutated. Exogenous miR-21 over-expression mimicked the effect of RhoB knockdown in promoting proliferation and invasion and inhibiting apoptosis, whereas anti-miR-21 or RhoB expression yielded opposite effects, in colorectal cancer cells. These results suggest that miR-21 is a regulator of RhoB expression and RhoB could be a useful target in exploring the potential therapeutic benefits of miR-21 mediated tumor cell behaviors in colorectal cancer.     

miR-137 inhibits glutamine catabolism and growth of malignant melanoma by targeting glutaminase

Glutamine catabolism is considered to be an important metabolic pathway for cancer cells. Glutaminase (GLS) is the important rate-limiting enzyme of glutamine catabolism. miR-137 functions as a tumor suppressor in many human malignant tumors. However, the role and molecular mechanism of miR-137 and GLS in malignant melanoma has not been reported. In this study, we showed that miR-137 was decreased in melanoma tissue, and the low miR-137 level and high GLS expression are independent risk factor in melanoma. miR-137 suppressed the proliferation and glutamine catabolism of melanoma cells. GLS is crucial for glutamine catabolism and growth of malignant melanoma. We also demonstrated that miR-137 acts as a tumor suppressor in melanoma by targeting GLS. This result elucidates a new mechanism for miR-137 in melanoma development and provides a survival indicator and potential therapeutic target for melanoma patients.