Maternally expressed gene 3 (MEG3): A tumor suppressor long non coding RNA

Long non-coding RNAs: Functional regulatory players in breast cancer.

Abstract Background One of the most malignant tumors in men is prostate cancer that is still incurable due to its heterogenous and progressive natures. Genetic and epigenetic changes play significant roles in its development. The RNA molecules with more than 200 nucleotides in length are known as lncRNAs and these epigenetic factors do not encode protein. They regulate gene expression at transcriptional, post-transcriptional and epigenetic levels. LncRNAs play vital biological functions in cells and in pathological events, hence their expression undergoes dysregulation. Aim of review The role of epigenetic alterations in prostate cancer development are emphasized here. Therefore, lncRNAs were chosen for this purpose and their expression level and interaction with other signaling networks in prostate cancer progression were examined. Key scientific concepts of review The aberrant expression of lncRNAs in prostate cancer has been well-documented and progression rate of tumor cells are regulated via affecting STAT3, NF-κB, Wnt, PI3K/Akt and PTEN, among other molecular pathways. Furthermore, lncRNAs regulate radio-resistance and chemo-resistance features of prostate tumor cells. Overexpression of tumor-promoting lncRNAs such as HOXD-AS1 and CCAT1 can result in drug resistance. Besides, lncRNAs can induce immune evasion of prostate cancer via upregulating PD-1. Pharmacological compounds such as quercetin and curcumin have been applied for targeting lncRNAs. Furthermore, siRNA tool can reduce expression of lncRNAs thereby suppressing prostate cancer progression. Prognosis and diagnosis of prostate tumor at clinical course can be evaluated by lncRNAs. The expression level of exosomal lncRNAs such as lncRNA-p21 can be investigated in serum of prostate cancer patients as a reliable biomarker. 

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Molecular Landscape of LncRNAs in Prostate Cancer: A focus on pathways and therapeutic targets for intervention

Melanoma is the most aggressive type of skin cancer with high mortality rate and poor prognosis. lncRNA MEG3, a tumor suppressor, is closely related to the development of various cancers. However, the role of lncRNA MEG3 in melanoma has seldom been studied. RT-PCR was used to examine the expressions of lncRNA MEG3 and E-cadherin in melanoma patients and cell lines. Then, the biological functions of lncRNA MEG3 and E-cadherin were demonstrated by transfecting lncRNA MEG3-siRNA, lncRNA MEG3-overexpression, E-cadherin-siRNA and E-cadherin-overexpression plasmids in melanoma cell lines. Moreover, CCK8 assay and colony formation assay were utilized to assess the cell proliferation; Transwell assay was performed to evaluate the cell invasive ability; and tumor xenografts in nude mice were applied to test the tumor generation. Additionally, the target interactions among lncRNA MEG3, miR-21 and E-cadherin were determined by dual luciferase reporter assay. Finally, RT-PCR and WB were further conducted to verify the regulatory roles among lncRNA MEG3, miR-21 and E-cadherin. The clinical data showed that lncRNA MEG3 and E-cadherin expressions were both declined in carcinoma tissues as compared with their para-carcinoma tissues. Moreover, lncRNA MEG3 and E-cadherin expressions in B16 cells were also higher than those in A375 and A2058 cells. Subsequently, based on the differently expressed lncRNA MEG3 and E-cadherin in these human melanoma cell lines, we chose B16, A375 and A2058 cells for the following experiments. The results demonstrated that lncRNA MEG3 could suppress the tumor growth, tumor metastasis and formation; and meanwhile E-cadherin had the same effects on tumor growth, tumor metastasis and formation. Furthermore, the analysis of Kaplan–Meier curves also confirmed that there was a positive correlation between lncRNA MEG3 and E-cadherin. Ultimately, dual luciferase assays were further used to verify that lncRNA MEG3 could directly target miR-21 which could directly target E-cadherin in turn. Additionally, the data of RT-PCR and WB revealed that knockdown of lncRNA MEG3 in B16 cells inhibited miR-21 expression and promoted E-cadherin expression, but overexpression of lncRNA MEG3 in A375 and A2058 cells presented completely opposite results. Our findings indicated that lncRNA MEG3 might inhibit the tumor growth, tumor metastasis and formation of melanoma by modulating miR-21/E-cadherin axis.

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LncRNA MEG3 promotes melanoma growth, metastasis and formation through modulating miR-21/E-cadherin axis

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This study was designed to detecting the influences of lncRNA MEG3 in prostate cancer. Aberrant lncRNAs expression profiles of prostate cancer were screened by microarray analysis. The qRT-PCR and Western blot were employed to investigating the expression levels of lncRNA MEG3, miR-9-5p and QKI-5. The luciferase reporter assay was utilized to testifying the interactions relationship among these molecules. Applying CCK-8 assay, wound healing assay, transwell assay and flow cytometry in turn, the cell proliferation, migration and invasion abilities as well as apoptosis were measured respectively. LncRNA MEG3 was a down-regulated lncRNA in prostate cancer tissues and cells and could inhibit the expression of miR-9-5p, whereas miR-9-5p down-regulated QKI-5 expression. Overexpressed MEG3 and QKI-5 could decrease the abilities of proliferation, migration and invasion in prostate cancer cells effectively and increased the apoptosis rate. On the contrary, miR-9-5p mimics presented an opposite tendency in prostate cancer cells. Furthermore, MEG3 inhibited tumour growth and up-regulated expression of QKI-5 in vivo. LncRNA MEG3 was a down-regulated lncRNA in prostate cancer and impacted the abilities of cell proliferation, migration and invasion, and cell apoptosis rate, this regulation relied on regulating miR-9-5p and its targeting gene QKI-5.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jcmm.13658

LncRNA MEG3 inhibits the progression of prostate cancer by modulating miR-9-5p/QKI-5 axis.

The function of androgen receptor (AR)/microRNA-21 (miR-21) axis in tumor development was well investigated. However, the roles of the axis performed in hypoxia/reoxygenation (H/R)-induced apoptosis of mouse renal tubular epithelial cells (RTECs) is not known. In this study, H/R-induced apoptosis of RTECs was established to evaluate the role of miR-21-AR axis. The protocol of 8-h hypoxia and 24-h reoxygenation were selected to produce H/R injury. Our data showed that H/R increased miR-21 and caspase-3 expression, reduced the expression AR and programmed cell death protein 4 (PDCD4). By contrast, AR-siRNA increased H/R-induced apoptosis, and promoted caspase-3 expression, but reduced PDCD4 expression (vs. H/R group). pre-miR-21 reduced, while antagomiR-21 promoted apoptosis and PDCD4 expression in H/R-induced RTECs. Moreover, pre-miR-21 promoted, while antagomiR-21 reduced caspase-3 expression in H/R-induced RTECs. Together, H/R increased miRNA-21 and reduced AR expression, then regulating PDCD4- and caspase-3-dependent apoptosis. AR/miR-21 axis could be a potential therapeutic target for the kidney ischemia injury.

Involvement of androgen receptor (AR)/microRNA-21 axis in hypoxia/reoxygenation-induced apoptosis of mouse renal tubular epithelial cells.

Objective To explore the effect and mechanism of moxibustion at acupoints of the governor vessel on lncRNA Six3os1 in amyloid precursor protein/presenilin1 (APP/PS1) double-transgenic Alzheimer's disease (AD) mice. Methods Twenty-four specific pathogen-free and APP/PS1 double-transgenic male mice were randomly allocated into the AD model and moxibustion groups, with 12 cases in each group. Twelve syngeneic C57BL/6J mice were selected as the control group. Mice in the moxibustion group received aconite cake-separated moxibustion at the Baihui acupoint. Suspension moxibustion was applied at Fengfu and Dazhui for 15 minutes each day. All treatments were conducted over two weeks. Control and AD model mice were routinely fed without any intervention. Behavioral observation tests were conducted before and after the intervention. The autophagosome in the hippocampus was observed using transmission electron microscopy. Immunohistochemistry was performed to detect Aβ1-42 expression. LC3B and P62 expressions were evaluated by immunofluorescence. The expression levels of the lncRNAs Six3os1, miR-511-3p, and AKT3 were detected by qRT-PCR. The differential expression of PI-3K, AKT3, mTOR, LC3B-II/I, and P62 proteins in the hippocampus was detected by western blot. The dual-luciferase assay was undertaken to examine the targeting relationships of the lncRNAs Six3os1, miR-511-3p, and AKT3. Results Compared with the control group, the AD model showed higher escape latency in the Morris Water Maze and reduced autophagic vacuoles in the cytoplasm of hippocampal neurons (both p < 0.01). Compared with the control group, the AD model showed higher expression of Aβ1-42, the lncRNAs Six3os1, PI-3K, mTOR, P62, and AKT3 protein (all p < 0.01); but lower mir-511-3p and LC3B (both p < 0.01). Compared with the AD model group, the moxibustion group had a shorter escape latency, more autophagic bubbles in the hippocampus, and lower expression of positive Aβ1-42, the lncRNAs Six3os1, PI-3K, mTOR, P62, and AKT3 protein (all p < 0.01). In contrast, the levels of miR-511-3p and LC3B proteins were considerably increased in the moxibustion group compared to the AD model group (both p < 0.01). Based on the dual-luciferase assay, there was a targeting link among the lncRNAs Six3os1, miR-511-3p, and AKT3. Conclusion Moxibustion at acupoints of the governor vessel can suppress the lncRNA Six3os1 expression, promote cell autophagy, accelerate Aβ1-42 clearance and alleviate cognitive dysfunction of AD mediated by the PI3K/AKT/mTOR signaling pathway through the lncRNA Six3os1/miR-511-3p/AKT3 axis.

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Effects on Autophagy of Moxibustion at Governor Vessel Acupoints in APP/PS1double-Transgenic Alzheimer's Disease Mice through the lncRNA Six3os1/miR-511-3p/AKT3 Molecular Axis

Meng Wu

Papers

LncRNA MEG3 inhibits the progression of prostate cancer by modulating miR-9-5p/QKI-5 axis.

Involvement of androgen receptor (AR)/microRNA-21 axis in hypoxia/reoxygenation-induced apoptosis of mouse renal tubular epithelial cells.

Effects on Autophagy of Moxibustion at Governor Vessel Acupoints in APP/PS1double-Transgenic Alzheimer's Disease Mice through the lncRNA Six3os1/miR-511-3p/AKT3 Molecular Axis