MicroRNA-770 affects proliferation and cell cycle transition by directly targeting CDK8 in glioma

Abstract

BackgroundMicroRNAs play crucial roles in tumorigenesis and tumor progression. miR-770 has been reported to be downregulated in several cancers and affects cancer cell proliferation, apoptosis, metastasis and drug resistance. However, the role and underlying molecular mechanism of miR-770 in human glioma remain unknown and need to be further elucidated.MethodsThe expression of miR-770 in glioma tissues and cell lines was measured by quantitative real-time PCR (qRT-PCR) to explore the association of miR-770 expression with clinicopathological characteristics. The expression of CDK8 was detected by qRT-PCR and Western blotting in glioma tissues. A target prediction program and a dual-luciferase reporter assay were used to confirm that CDK8 is a target gene of miR-770. MTT and cell counting assays were used to assess the effect of miR-770 on glioma cell proliferation. The cell cycle distribution and apoptosis were examined by flow cytometry. CDK8 siRNA and overexpression were used to further confirm the function of the target gene.ResultsWe demonstrated that miR-770 expression was downregulated in human glioma tissues and cell lines. The overexpression of miR-770 inhibited glioma cell proliferation and cell cycle G1-S transition and induced apoptosis. The inhibition of miR-770 facilitated cell proliferation and G1-S transition and suppressed apoptosis. miR-770 expression was inversely correlated with CDK8 expression in glioma tissues. CDK8 was confirmed to be a direct target of miR-770 by using a luciferase reporter assay. The overexpression of miR-770 decreased CDK8 expression at both the mRNA and protein levels, and the suppression of miR-770 increased CDK8 expression. Importantly, CDK8 silencing recapitulated the cellular and molecular effects observed upon miR-770 overexpression, and CDK8 overexpression eliminated the effects of miR-770 overexpression on glioma cells. Moreover, both exogenous expression of miR-770 and silencing of CDK8 resulted in suppression of the Wnt/β-catenin signaling pathway.ConclusionsOur study demonstrates that miR-770 inhibits glioma cell proliferation and G1-S transition and induces apoptosis through suppression of the Wnt/β-catenin signaling pathway by targeting CDK8. These findings suggest that miR-770 plays a significant role in glioma progression and serves as a potential therapeutic target for glioma.

miR‑770‑5p modulates resistance to methotrexate in human colorectal adenocarcinoma cells by downregulating HIPK1

“…Zhang et al (22) previously demonstrated that miR-770-5p was upregulated in the in vitro model of diabetic nephropathy (DN) and that it may promote the development of DN by regulating podocyte apoptosis through targeting tp53 regulated inhibitor of apoptosis 1. Another previous study revealed that miR-770 inhibits glioma cell proliferation and induces apoptosis through the suppression of the Wnt/β-catenin signaling pathway by targeting cyclin-dependent kinase 8, suggesting that miR-770 may serve a crucial role in glioma progression and may be used as a potential novel target for glioma therapy (23). A recent study demonstrated that when the expression of mir-770-5p is inhibited, cell radiosensitivity is decreased, which suggested that miR-770-5p may be a useful therapeutic target miRNA that sensitizes tumors to radiation through negative regulation of PBK (24).…”

<p>Circ_0006528 Contributes to Paclitaxel Resistance of Breast Cancer Cells by Regulating miR-1299/CDK8 Axis</p>

“…14 Emerging studies indicated that CDK8 was overexpressed and accelerated the progression of tumor cells in multiple cancers, such as colon cancer, 15 pancreatic cancer 16 and glioma. 17 Importantly, Li et al found that CDK8 was associated with sensitivity of PTX in NCI60 cells. 18 But the interaction among circ_0006528, miR-1299 and CDK8 in breast cancer remains unknown.…”

Analysis of microarray data for identification of key microRNA signatures in glioblastoma multiforme

“…This miRNA could also be a useful biomarker for predicting the chemoresistance towards cisplatin in ovarian cancer patients and was found to act as a tumor suppressor by downregulating ERCC2 expression (23). Reduced expression of hsa-miRNA-770-5p was observed in higher stages of glioma (WHO grade III and IV) as compared to lower stages (WHO grade I and II) (19).…”

“…Previous studies have shown downregulation of miRNA-770-5p in tumors associated with the brain such as gliomas (19) and medulloblastomas (MB) (20). Even amongst different types of brain cancers, the expression levels of hsa-miR-770-5p was significantly lower in MB as compared to astrocytomas (21).…”