Decreased expression of MEG3 contributes to retinoblastoma progression and affects retinoblastoma cell growth by regulating the activity of Wnt/β-catenin pathway

Aberrant Methylation of MEG3 Functions as a Potential Plasma-Based Biomarker for Cervical Cancer

Methylation alterations of specific genes have recently been identified as diagnostic biomarkers for human cancers. Although MEG3 has been proved to be a tumor suppressor in cervical cancer according to our previous study, the diagnostic value of MEG3 methylation in plasma is still unknown. Therefore, the aim of this study is to identify a novel epigenetic biomarker for cervical cancer. In the current study, the level of MEG3 methylation was evaluated using methylation-specific polymerase chain reaction. The results showed that the level of MEG3 methylation was significantly higher in cervical cancer tissues and patients' plasmas than those in adjacent normal tissues and plasmas of healthy participants respectively. Moreover, the accuracy was good enough for MEG3 methylation in plasma to discriminate CIN III patients from healthy participants. In addition, MEG3 methylation in plasma also has high discriminating power to predict HR-HPV infection and lymph node metastasis. Furthermore, hypermethylation of MEG3 in plasma was associated with worse recurrence-free and overall survival in cervical cancer patients. In conclusions, MEG3 methylation in plasma can serve as a diagnostic and prognostic biomarker for cervical cancer, providing useful information for clinical management.

CCAT-1 promotes proliferation and inhibits apoptosis of cervical cancer cells via the Wnt signaling pathway

Though the long noncoding RNA colon cancer associated transcript-1 (CCAT-1) has been shown to be involved in tumors of other tissues, its involvement in cervical cancer is still unknown. Therefore, the aim of this study was to investigate the molecular mechanism of CCAT-1 in cervical cancer. We quantified the expression of CCAT-1 long noncoding RNA in samples of cervical cancer tissue by real-time PCR. Effects of CCAT-1 expression on the proliferation and apoptosis of HeLa and CaSki cells were assessed by cell-count, colony-formation, and flow cytometry assays. Binding of the c-Myc protein to the CCAT-1 promoter was confirmed by chromatin immunoprecipitation. Finally, TOP-Flash and western blotting were used to examine the regulation of the Wnt/β-catenin pathway by CCAT-1. The results showed that compared with adjacent normal tissue, the expression of CCAT-1 in cervical cancer tissue was significantly upregulated. CCAT-1 expression was related to the stage and size of the tumor and recurrence prognosis. Then, we showed through functional assays that CCAT-1 could promote proliferation and inhibit apoptosis of cervical cancer cells. Furthermore, chromatin immunoprecipitation showed that c-Myc protein could promote CCAT-1 expression by binding to its promoter. Finally, fluorescent-reporter assays and western blotting showed that CCAT-1 could activate the Wnt/β-catenin pathway. In conclusion, we showed that CCAT-1 can be activated by the c-Myc protein and it can promote proliferation and inhibit apoptosis in cervical cancer cells by regulating the Wnt/β-catenin pathway. CCAT-1 might serve as a good prognostic indicator and target for treatment of cervical cancer.

Precise long non-coding RNA modulation in visual maintenance and impairment

Long non-coding RNAs (lncRNAs) are remarkably powerful, flexible and pervasive cellular regulators. With the help of cheaper RNA-seq, high-throughput screening of lncRNAs has become widely applied and has identified large numbers of specific lncRNAs in various physiological or pathological processes. Vision is known to be a complex and vital perception that comprises 80% of the sensory information we receive. A consensus has been reached that normal visual maintenance and impairment are primarily driven by gene regulation. Recently, it has become understood that lncRNAs are key regulators in most biological processes, including cell proliferation, apoptosis, differentiation, immune responses, oxidative stress and inflammation. Our review is intended to provide insight towards a comprehensive view of the precise modulation of lncRNAs in visual maintenance and impairment. We also highlight the challenges and future directions in conducting lncRNA studies, particularly in patients whose lncRNAs may hold expanded promise for diagnostic, prognostic and therapeutic applications.

Biological function and mechanism of lncRNA-MEG3 in Tenon's capsule fibroblasts proliferation: By MEG3-Nrf2 protein interaction

OBJECTIVE

The proliferation of Tenon's capsule fibroblasts after glaucoma filtration surgery is a harmful element for operation failure. However, the underlying mechanism remains unclear. In this study, we evaluated the role of long non-coding RNA (lncRNA)-MEG3 in the proliferation of Glaucoma Tenon's capsule fibroblasts (GTFs) with a model of transforming growth factor-β (TGF-β)-induced proliferation which has been used in previous studies to explore the mechanism underlying glaucoma surgery failure.

METHODS

In vitro cell proliferation model was made by TGF-β2 (5ng/mL)-stimulated GTFs obtained from patients with glaucoma filtration surgery, and cell viability and cell proliferation was assessed by MTT assay and [3H] thymidine incorporation assay respectively. Relative expression of MEG3 and Nrf2 mRNA was determined by quantitative real-time PCR. Nrf2 protein level was detected by western blot. Functional interaction between MEG3 and Nrf2 was examined by RNA pull down and RNA Binding Protein Immunoprecipitation (RIP).

RESULTS

As detected in isolated Tenon's capsule fibroblasts, expression level of both MEG3 and Nrf2 is decreased in GTFs compared with control fibroblasts (HTFs). Adenovirus mediated overexpression of MEG3 attenuates cell ability and cell proliferation, as well as contributed to upregulation of Nrf2 protein in TGF-β2-stimualted GTFs. MEG3 positively affects the expression of Nrf2 protein rather than Nrf2 mRNA. We found that this functional interaction of them depends on MEG3-Nrf2 protein formation by RNA pull down and RIP analysis and also is proved to be involved in TGF-β2-induced cell proliferation.

CONCLUSION

The above data suggested that the functional interaction between lncRNA-MEG3 and Nrf2 constitutes the mechanism by which TGF-β2 induces Tenon's capsule fibroblasts proliferation after glaucoma filtration surgery via the direct binding of MEG3 to Nrf2.

Downregulation of long noncoding RNA MEG3 is associated with poor prognosis and promoter hypermethylation in cervical cancer

Background

Our previous study reported that MEG3 is an important tumor suppressor gene that is inactivated in cervical cancer. However, the diagnostic and prognostic values of MEG3, as well as the molecular mechanism of MEG3 inactivation in cervical cancer, remain unclear. In this study, we aimed to further elucidate the role and potential inactivation mechanism of MEG3 in cervical cancer.

Methods

ROC curve and Cox regression analyses were used to assess the diagnostic and prognostic value of MEG3 in patients with cervical cancer. The methylation status of the MEG3 promoter in cervical cancer tissue samples was tested using methylation-specific PCR. Furthermore, we altered the methylation status of the MEG3 promoter in two cervical cancer cell lines (HeLa and CaSki) using a DNA methylation transfer enzyme inhibitor (5-Aza-CdR), to investigate whether promoter hypermethylation is a potential cause of MEG3 inactivation. Finally, we used CCK-8 and colony formation assays to evaluate the cell proliferation ability of HeLa and CaSki cells that had been treated with 5-aza-CdR, to investigate whether downregulation of MEG3 caused by promoter hypermethylation had biological effects.

Results

ROC curve analysis indicated that MEG3 status showed sufficient sensitivity and specificity for prediction of tumor size and lymph node metastasis in patients with cervical cancer. In addition, our follow-up data showed that low MEG3 expression was correlated with recurrence and short overall survival. Moreover, hypermethylation of the MEG3 promoter was observed in most cervical cancer tissue samples, and demethylation of the MEG3 promoter led to re-expression of MEG3 and inhibited proliferation of HeLa and CaSki cells.

Conclusions

MEG3 is a powerful tool for diagnosis and prognosis of patients with cervical cancer, and low expression of MEG3 is likely to be related to promoter hypermethylation in cervical cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0472-2) contains supplementary material, which is available to authorized users.

Novel Insights into the Role of Long Noncoding RNA in Ocular Diseases

Recent advances have suggested that long noncoding RNAs (lncRNAs) are differentially expressed in ocular tissues and play a critical role in the pathogenesis of different types of eye diseases. Here, we summarize the functions and mechanisms of known aberrantly-expressed lncRNAs and present a brief overview of relevant reports about lncRNAs in such ocular diseases as glaucoma, proliferative vitreoretinopathy (PVR), diabeticretinopathy (DR), and ocular tumors. We intend to highlight comprehensive studies that provide detailed data about the mechanisms of lncRNAs, their applications as diagnostic or prognostic biomarkers, and their potential therapeutic targets. Although our understanding of lncRNAs is still in its infancy, these examples may provide helpful insights into the methods by which lncRNAs interfere with ocular diseases.