A cytoplasmic long noncoding RNA LINC00470 as a new AKT activator to mediate glioblastoma cell autophagy

Targeting the estrogen receptor alpha (ERα)-mediated circ-SMG1.72/miR-141-3p/Gelsolin signaling to better suppress the HCC cell invasion

Early studies indicated that estrogen receptor α (ERα) might impact the progression of hepatocellular carcinoma (HCC). However, the detailed mechanisms, especially its linkage to the gelsolin (GSN)-mediated cell invasion, remain unclear. Here we found that ERα could decrease HCC cell invasion via suppressing the circular RNA-SMG1.72 (circRNA-SMG1.72) expression via transcriptional regulation through directly binding to the 5' promoter region of its host gene SMG1, We showed that ERα-suppressed circ-SMG1.72 could sponge and inhibit the expression of the microRNA (miRNA, miR), miR-141-3p, which could then result in increasing the GSN messenger RNA translation via reduced miR binding to its 3' untranslated region (3'UTR). The preclinical study using an in vivo mouse model with orthotopic xenografts of HCC cells confirmed the in vitro data, and the human HCC clinical sample survey and tissue staining also confirmed the linkage of ERα/miR-141-3p/GSN signaling to the HCC progression. Together, our findings suggest that ERα can suppress HCC cell invasion via altering the ERα/circRNA-SMG1.72/miR-141-3p/GSN signaling, and targeting this newly identified signaling with small molecules may help in the development of novel therapies to better suppress the HCC progression.

lncRNA RMST Suppressed GBM Cell Mitophagy through Enhancing FUS SUMOylation

Long non-coding RNAs (lncRNAs) play a significant role in post-translational modifications of proteins, yet the importance of lncRNAs for SUMOylation is unknown. rhabdomyosarcoma 2 associated transcript (RMST) expression in glioma tissues and normal brain tissues was measured by quantitative real-time PCR and in situ hybridization. The functional roles of RMST in astrocytomas were demonstrated by a series of in vitro experiments. The potential mechanisms of RMST for SUMOylation were investigated by RNA immunoprecipitation, RNA pull-down, western blotting, and coimmunoprecipitation assays. We first demonstrated the oncogenic activity of lncRNA RMST by inhibiting glioma cells mitophagy. We also first determined that RMST is an enhancer of FUS SUMOylation, especially boosting SUMO1 modification at K333. SUMOylation induced by RMST contributes to the interaction between FUS and heterogeneous nuclear ribonucleoprotein D (hnRNPD) and stabilized their expression and cells mitophagy. Importantly, lncRNA RMST could serve as a promising prognostic factor for glioma patients. Our results demonstrated a previously unknown function of lncRNAs worked as an enhancer in FUS SUMOylation, and RMST will be a significant guide for the development of medications targeting gliomas.

LncRNAs: The Regulator of Glucose and Lipid Metabolism in Tumor Cells

Metabolism is a complex network of regulatory system. Cells often alter their metabolism in response to the changes in their environment. These adaptive changes are particularly pronounced in tumor cells, known as metabolic reprogramming. Metabolic reprogramming is considered to be one of the top 10 characteristics of tumor cells. Glucose and lipid metabolism are important components of metabolic reprogramming. A large number of experimental studies have shown that long non-coding RNAs (lncRNAs) play an important role in glucose and lipid metabolism. The current review briefly introduces the regulatory effect of lncRNAs on glucose and lipid metabolism of tumor cells, and the significance of lncRNA-mediated metabolism in tumor therapy, hoping to provide new strategies for clinical targeting tumor therapy.

LncRNA LINC00470 promotes the degradation of PTEN mRNA to facilitate malignant behavior in gastric cancer cells

Gastric cancer (GC) is the fourth most frequent malignancy worldwide. Recently, long noncoding RNA (lncRNA) LINC00470 has been demonstrated to play an oncogenic role in human cancer. However, the clinical significance and functional role of LINC00470 in the progression of GC is largely unknown. In this study, our findings showed that LINC00470 was significantly upregulated in GC tissues and cell lines, and correlated with distant metastasis, TNM stage and poor prognosis. Overexpression and knockdown experiments revealed its oncogenic functions on GC cell proliferation, migration and invasion. Mechanistically, LINC00470 associated with PTEN mRNA and suppressed its stability through interaction with the N⁶-methyladenosine (m⁶A) writer METTL3. We also showed that LINC00470-METTL3-mediated PTEN mRNA degradation relied on the m⁶A reader protein YTHDF2-dependent pathway. Taken together, LINC00470 might serve as a therapeutic target for GC patients.

LncRNA LINC00470 promotes proliferation through association with NF45/NF90 complex in hepatocellular carcinoma

Increasing evidence demonstrates that long noncoding RNAs (lncRNAs) play an important role in the development and progression of human cancers. LncRNA LINC00470 has been reported to function as an oncogene in glioblastoma. Until now, the roles and underlying mechanisms of LINC00470 in the progression of hepatocellular carcinoma (HCC) remain unclear. Here, we found that LINC00470 was upregulated in HCC cells and tissues. High-level LINC00470 was significantly correlated with bigger tumor size, advanced TNM stage and poor prognosis in patients with HCC. Functional studies showed that knockdown of LINC00470 expression inhibited HCC cell proliferation and cell cycle progression, while overexpression of LINC00470 showed the opposite effects. Further investigation suggested that LINC00470 was associated with NF45/NF90 complex and increased its interaction with cyclin E1 mRNA, thus inhibiting the degradation of cyclin E1 mRNA. Additionally, knockdown of cyclin E1 in LINC00470-overexpressed cells abolished its promotive effects on HCC cell proliferation. In summary, our findings suggest that targeting LINC00470 could be a potential therapeutic approach in treating HCC patients.

Long Non-coding RNA ITIH4-AS1 Accelerates the Proliferation and Metastasis of Colorectal Cancer by Activating JAK/STAT3 Signaling

Accumulating evidence has uncovered long non-coding RNAs (lncRNAs) as central regulators in the pathogenesis of diverse human cancers including colorectal cancer (CRC). The present study discovered that a novel lncRNA ITIH4 antisense RNA 1 (ITHI4-AS1) was frequently under-expressed in most normal human tissues, including colon tissues. Therefore, we aimed to investigate the role of ITHI4-AS1 in CRC. Interestingly, a significant overexpression of ITIH4-AS1 was observed in CRC cell lines relative to normal NCM460 cells. Also, we investigated the facilitating role of ITIH4-AS1 in CRC cell growth and metastasis both in vitro and in vivo. Additionally, we explained that ITIH4-AS1 upregulation in CRC was attributed to downregulation or even depletion of RE1 silencing transcription factor (REST), a presently identified transcriptional repressor for ITIH4-AS1. Meanwhile, the contribution of ITIH4-AS1 to CRC development was validated to rely on the activation of the JAK/STAT3 pathway. More importantly, we verified that FUS interacted with both ITIH4-AS1 and STAT3, and that ITIH4-AS1 evoked nuclear translocation of phosphorylated (p)-STAT3 in CRC through recruiting FUS. In summary, our findings unveiled for the first time that REST downregulation-enhanced ITIH4-AS1 exerts pro-tumor functions in CRC through FUS-dependent activation of the JAK/STAT3 pathway, implying that targeting ITIH4-AS1 may be a novel effective strategy for CRC therapy.

Long non-coding RNA LINC00526 represses glioma progression via forming a double negative feedback loop with AXL

Glioma is the most common primary intracranial carcinoma with extremely poor prognosis. The significances of long non‐coding RNA (lncRNA) involved in glioma have been started revealed. However, the expression, roles and molecular mechanisms of most lncRNAs in glioma are still unknown. In this study, we identified a novel lncRNA LINC00526, which is significantly low expressed in glioma. Low expression of LINC00526 is correlated with aggravation and poor survival in glioma. Functional assays revealed that ectopic expression of LINC00526 inhibits glioma cell proliferation, migration, and invasion. LINC00526 silencing promotes glioma cell proliferation, migration and invasion. Mechanistically, we found that LINC00526 directly interacts with EZH2, represses the binding of EZH2 to AXL promoter, attenuates the transcriptional activating roles of EZH2 on AXL, and therefore represses AXL expression. Via repressing AXL, LINC00526 further represses PI3K/Akt/NF‐κB signalling. Intriguingly, we identified that NFKB1 and NFKB2 directly binds LINC00526 promoter and represses LINC00526 transcription. We further found that via activating NF‐κB signalling, AXL represses LINC00526 transcription. Therefore, LINC00526/EZH2/AXL/PI3K/Akt/NF‐κB form a feedback loop in glioma. Analysis of the TCGA data revealed that the expression of LINC00526 is inversely correlated with that of AXL in glioma tissues. In addition, functional rescue assays revealed that the tumour suppressive roles of LINC00526 are dependent on the negative regulation of AXL. Collectively, our data identified LINC00526 as a tumour suppressor in glioma via forming a double negative feedback loop with AXL. Our data also suggested LINC00526 as a potential prognostic biomarker and therapeutic candidate for glioma.

Noncoding RNAs in cancer therapy resistance and targeted drug development

Noncoding RNAs (ncRNAs) represent a large segment of the human transcriptome and have been shown to play important roles in cellular physiology and disease pathogenesis. Increasing evidence on the functional roles of ncRNAs in cancer progression emphasizes the potential of ncRNAs for cancer treatment. Here, we summarize the roles of ncRNAs in disease relapse and resistance to current standard chemotherapy and radiotherapy; the current research progress on ncRNAs for clinical and/or potential translational applications, including the identification of ncRNAs as therapeutic targets; therapeutic approaches for ncRNA targeting; and ncRNA delivery strategies in potential clinical translation. Several ongoing clinical trials of novel RNA-based therapeutics were also emphasized. Finally, we discussed the perspectives and obstacles to different target combinations, delivery strategies, and system designs for ncRNA application. The next approved nucleic acid drug to treat cancer patients may realistically be on the horizon.

Akt in cancer: Mediator and more

Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.

Linc01230, transcriptionally regulated by PPARγ, is identified as a novel modifier in endothelial function

Evidence is growing that PPARγ could improve the bioavailability of NO in pathological conditions to maintain endothelial function by activating Akt/eNOS pathway. LincRNAs participate in regulating development of cardiovascular diseases. Although investigations have been made to delineate the function of PPARγ and lincRNAs, little is known about the regulation relationship between them, especially in endothelial cells. In this study, we not only verified that PPARγ could antagonize the adverse effects brought from ox-LDL, but also found a novel factor related to PPARγ, named linc01230. According to our study, PPARγ transcriptionally regulated linc01230 by specifically combining with two binding regions, which have superposition effect, in the upstream of linc01230 promoter. In addition, linc01230 reduced ox-LDL induced endothelial dysfunction and affected the phosphorylation of Akt. These results conclude linc01230 as a novel modifier in PPARγ-mediated activation of Akt in endothelial function.

Immunotherapy and Epigenetic Pathway Modulation in Glioblastoma Multiforme

Glioblastoma Multiforme (GBM) is the most common malignant primary brain tumor. Despite aggressive multimodality treatment it remains one of the most challenging and intractable cancers (1]. While current standard of care treatment for GBM is maximal safe surgical resection, systemic chemotherapy with Temozolimide (TMZ), and radiation therapy, the current prognosis of GBM patients remains poor, with a median overall survival of 12–15 months (2, 3). Therefore, other treatments are needed to provide better outcomes for GBM patients. Immunotherapy is one of the most promising new cancer treatment approaches. Immunotherapy drugs have obtained regulatory approval in a variety of cancers including melanoma (4), Hodgkin lymphoma (5), and non-small cell lung cancer (6). The basis of immunotherapy in cancer treatment is linked to stimulating the immune system to recognize cancer cells as foreign, thereby leading to the eventual elimination of the tumor. One form of immunotherapy utilizes vaccines that target tumor antigens (7), while other approaches utilize T-cells in patients to stimulate them to attack tumor cells (8). Despite intensive efforts all approaches have not been overtly successful (9), suggesting that we need to better understand the underlying biology of tumor cells and their environment as they respond to immunotherapy. Recent studies have elucidated epigenetic pathway regulation of GBM tumor expansion (10), suggesting that combined epigenetic pathway inhibition with immunotherapy may be feasible. In this review, we discuss current GBM clinical trials and how immune system interactions with epigenetic pathways and signaling nodes can be delineated to uncover potential combination therapies for this incurable disease.

Regulatory effects of lncRNAs and miRNAs on autophagy in malignant tumorigenesis

Autophagy is an important process in endogenous substrate degradation by lysosomes within cells, with a degree of evolutionary conservation. Like apoptosis and cell senescence, cell autophagy is a very important biological phenomenon involving the development and growth of biological processes. Abnormal autophagy may lead to tumorigenesis. In recent years, increasing studies have demonstrated that long non-coding RNAs (lncRNAs) and miRNAs can regulate cell autophagy by modulating targetting gene expression. In this review, we will provide an overview of lncRNAs and miRNAs in autophagy modulation and new insights into the underlying mechanisms, as well as their potential utilization in disease diagnosis, prognosis, and therapy.

Emerging roles of long non-coding RNAs in tumor metabolism

Compared with normal cells, tumor cells display distinct metabolic characteristics. Long non-coding RNAs (lncRNAs), a large class of regulatory RNA molecules with limited or no protein-coding capacity, play key roles in tumorigenesis and progression. Recent advances have revealed that lncRNAs play a vital role in cell metabolism by regulating the reprogramming of the metabolic pathways in cancer cells. LncRNAs could regulate various metabolic enzymes that integrate cell malignant transformation and metabolic reprogramming. In addition to the known functions of lncRNAs in regulating glycolysis and glucose homeostasis, recent studies also implicate lncRNAs in amino acid and lipid metabolism. These observations reveal the high complexity of the malignant metabolism. Elucidating the metabolic-related functions of lncRNAs will provide a better understanding of the regulatory mechanisms of metabolism and thus may provide insights for the clinical development of cancer diagnostics, prognostics and therapeutics.

LINC00470 Coordinates the Epigenetic Regulation of ELFN2 to Distract GBM Cell Autophagy

The epigenetics and genomics of glioblastoma (GBM) are complicated. Previous reports indicate that ELFN2 is widely distributed in the cerebral cortex neurons, striatum, and hippocampus cone and in granular cells. However, the function and mechanism of ELFN2, particularly in GBM, have rarely been explored. In this study, we identified ELFN2 as a new hypomethylation gene that acts as an oncogene in GBM. ELFN2 promoted cell autophagy by interacting with AurkA and eIF2α and inhibiting the activation of AurkA. We also demonstrated that aberrantly high ELFN2 expression is obtained due to hypomethylation of its promoter and abnormal miR-101 and LINC00470 expression in GBM. LINC00470 not only enhanced the expression of ELFN2 through adsorption of miR-101 but also affected the methylation level of ELFN2 by decreasing H3K27me3 occupancy. In addition, LINC00470 played a dominant role in the regulation of GBM cell autophagy, even though it upregulated ELFN2 expression. The results indicate that the combination of LINC00470 and ELFN2 has important significance for evaluating the prognosis of astrocytoma patients.