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MicroRNA-218 inhibits the proliferation and metastasis of esophageal squamous cell carcinoma cells by targeting BMI1.

Wang T, Chen T, Niu H, Li C, Xu C, Li Y, Huang R, Zhao J, Wu S - Int. J. Mol. Med. (2015)

Bottom Line: MicroRNAs (miRNAs or miRs) play a pivotal role in esophageal carcinogenesis either as oncogenes or as tumor suppressor genes.Furthermore, the decreased expression of miR-218 was found to be associated with an enhanced ESCC cell proliferation and metastasis.In the present study, our findings confirm miR-218 as a tumor suppressor and identify BMI1 as a novel target of miR-218 in ESCC.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Medical College of Soochow University, Suzhou, Jiangsu 215123, P.R. China.

ABSTRACT
MicroRNAs (miRNAs or miRs) play a pivotal role in esophageal carcinogenesis either as oncogenes or as tumor suppressor genes. In the present study, we found that the expression level of miR-218 was significantly reduced in esophageal squamous cell carcinoma (ESCC) tissues and ESCC cell lines. Moreover, its expression was found to correlate with the clinicopathological stage of ESCC; miR-218 expression was lower in the stage III tissue samples than in the stage I and II tissue samples. Furthermore, the decreased expression of miR-218 was found to be associated with an enhanced ESCC cell proliferation and metastasis. Western blot analysis and luciferase reporter assay revealed that miR-218 decreased BMI1 expression by binding to the putative binding sites in its 3'-untranslated region (3'-UTR). The BMI1 mRNA expression levels were markedly increased and negatively correlated with the miR-218 expression level in the ESCC tissues. Functional analyses revealed that the restoration of miR-218 expression inhibited ESCC cell proliferation, migration and invasion and promoted apoptosis. The knockdown of BMI1 by siRNA showed the same phenocopy as the effect of miR-218 on ESCC cells, indicating that BMI1 was a major target of miR-218. In the present study, our findings confirm miR-218 as a tumor suppressor and identify BMI1 as a novel target of miR-218 in ESCC. Therefore, miR-218 may prove to be a useful biomarker for monitoring the initiation and development of ESCC, and may thus be an effective therapeutic target in ESCC.

No MeSH data available.


Related in: MedlinePlus

Partial reversal of the inhibitory effects of miR-218 on the ESCC cell phenotype by BMI1. (A) Western blot analysis of BMI1 protein levels in EC109 cells which were co-transfected with miR-218 mimics or miR-control and the BMI1 plasmid (without 3′-UTR) or vector control. (B) MTT assay of relative EC109 cell viability. (C) Wound healing assay. (D) Transwell invasion assay. Data are presented as the means ± SD from 3 replicate samples. *P<0.05 and **P<0.01.
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f5-ijmm-36-01-0093: Partial reversal of the inhibitory effects of miR-218 on the ESCC cell phenotype by BMI1. (A) Western blot analysis of BMI1 protein levels in EC109 cells which were co-transfected with miR-218 mimics or miR-control and the BMI1 plasmid (without 3′-UTR) or vector control. (B) MTT assay of relative EC109 cell viability. (C) Wound healing assay. (D) Transwell invasion assay. Data are presented as the means ± SD from 3 replicate samples. *P<0.05 and **P<0.01.

Mentions: Since our results suggested that miR-218 inhibited cell growth and invasion through teh downregulation of BMI1, we explored whether BMI1 is a direct functional mediator of the inhibitory effects of miR-218. The EC109 cells were transfected with BMI1 plasmid without the 3′-UTR or control plasmid, in combination with transfection with miR-218 or miR-control. Forty hours after the BMI1 plasmid or the control vector were co-transfected with the miR-218 or miR-control into the cells, western blot analysis confirmed that miR-218 downregulated BMI1 expression; however, this effect was reversed by transfection with BMI1 plasmid (Fig. 5A). It was also suggested that the BMI1 construct without the 3′-UTR was insensitive to miR-218-mediated inhibition. MTT assay revealed that the overexpression of BMI1 significantly reversed miR-218-induced cell growth inhibition (Fig. 5B). Furthermore, BMI1 partially reversed the inhibitory effects of miR-218 on EC109 cell migration and invasion (Fig. 5C and D). These results suggested that the overexpression of BMI1 reversed the effects of the aberrant expression of miR-218 on the phenotype of ESCC cells.


MicroRNA-218 inhibits the proliferation and metastasis of esophageal squamous cell carcinoma cells by targeting BMI1.

Wang T, Chen T, Niu H, Li C, Xu C, Li Y, Huang R, Zhao J, Wu S - Int. J. Mol. Med. (2015)

Partial reversal of the inhibitory effects of miR-218 on the ESCC cell phenotype by BMI1. (A) Western blot analysis of BMI1 protein levels in EC109 cells which were co-transfected with miR-218 mimics or miR-control and the BMI1 plasmid (without 3′-UTR) or vector control. (B) MTT assay of relative EC109 cell viability. (C) Wound healing assay. (D) Transwell invasion assay. Data are presented as the means ± SD from 3 replicate samples. *P<0.05 and **P<0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494586&req=5

f5-ijmm-36-01-0093: Partial reversal of the inhibitory effects of miR-218 on the ESCC cell phenotype by BMI1. (A) Western blot analysis of BMI1 protein levels in EC109 cells which were co-transfected with miR-218 mimics or miR-control and the BMI1 plasmid (without 3′-UTR) or vector control. (B) MTT assay of relative EC109 cell viability. (C) Wound healing assay. (D) Transwell invasion assay. Data are presented as the means ± SD from 3 replicate samples. *P<0.05 and **P<0.01.
Mentions: Since our results suggested that miR-218 inhibited cell growth and invasion through teh downregulation of BMI1, we explored whether BMI1 is a direct functional mediator of the inhibitory effects of miR-218. The EC109 cells were transfected with BMI1 plasmid without the 3′-UTR or control plasmid, in combination with transfection with miR-218 or miR-control. Forty hours after the BMI1 plasmid or the control vector were co-transfected with the miR-218 or miR-control into the cells, western blot analysis confirmed that miR-218 downregulated BMI1 expression; however, this effect was reversed by transfection with BMI1 plasmid (Fig. 5A). It was also suggested that the BMI1 construct without the 3′-UTR was insensitive to miR-218-mediated inhibition. MTT assay revealed that the overexpression of BMI1 significantly reversed miR-218-induced cell growth inhibition (Fig. 5B). Furthermore, BMI1 partially reversed the inhibitory effects of miR-218 on EC109 cell migration and invasion (Fig. 5C and D). These results suggested that the overexpression of BMI1 reversed the effects of the aberrant expression of miR-218 on the phenotype of ESCC cells.

Bottom Line: MicroRNAs (miRNAs or miRs) play a pivotal role in esophageal carcinogenesis either as oncogenes or as tumor suppressor genes.Furthermore, the decreased expression of miR-218 was found to be associated with an enhanced ESCC cell proliferation and metastasis.In the present study, our findings confirm miR-218 as a tumor suppressor and identify BMI1 as a novel target of miR-218 in ESCC.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Medical College of Soochow University, Suzhou, Jiangsu 215123, P.R. China.

ABSTRACT
MicroRNAs (miRNAs or miRs) play a pivotal role in esophageal carcinogenesis either as oncogenes or as tumor suppressor genes. In the present study, we found that the expression level of miR-218 was significantly reduced in esophageal squamous cell carcinoma (ESCC) tissues and ESCC cell lines. Moreover, its expression was found to correlate with the clinicopathological stage of ESCC; miR-218 expression was lower in the stage III tissue samples than in the stage I and II tissue samples. Furthermore, the decreased expression of miR-218 was found to be associated with an enhanced ESCC cell proliferation and metastasis. Western blot analysis and luciferase reporter assay revealed that miR-218 decreased BMI1 expression by binding to the putative binding sites in its 3'-untranslated region (3'-UTR). The BMI1 mRNA expression levels were markedly increased and negatively correlated with the miR-218 expression level in the ESCC tissues. Functional analyses revealed that the restoration of miR-218 expression inhibited ESCC cell proliferation, migration and invasion and promoted apoptosis. The knockdown of BMI1 by siRNA showed the same phenocopy as the effect of miR-218 on ESCC cells, indicating that BMI1 was a major target of miR-218. In the present study, our findings confirm miR-218 as a tumor suppressor and identify BMI1 as a novel target of miR-218 in ESCC. Therefore, miR-218 may prove to be a useful biomarker for monitoring the initiation and development of ESCC, and may thus be an effective therapeutic target in ESCC.

No MeSH data available.


Related in: MedlinePlus