MicroRNA-101 reverses temozolomide resistance by inhibition of GSK3β in glioblastoma

Comprehensive systems biology analysis of microRNA-101-3p regulatory network identifies crucial genes and pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide. This study aimed to explore the role of hsa-miR-101-3p in HCC pathogenesis by identifying key genes and pathways. A comprehensive bioinformatics analysis revealed twelve hub genes (ETNK1, BICRA, IL1R1, KDM3A, ARID2, GSK3β, EZH2, NOTCH1, SMARCA4, FOS, CREB1, and CASP3) and highlighted their involvement in crucial oncogenic pathways, including PI3K/Akt, mTOR, MAPK, and TGF-β. Gene expression analysis showed significant overexpression of ETNK1, KDM3A, EZH2, SMARCA4, and CASP3 in HCC tissues, correlating with poorer survival outcomes. Drug screening identified therapeutic candidates, including Tazemetostat for EZH2 and lithium compounds for GSK3β, underscoring their potential for targeted treatment. These findings provide novel insights into the complexity of HCC pathogenesis, suggesting that the identified hub genes could serve as diagnostic or prognostic biomarkers and therapeutic targets. While bioinformatics-driven, this study offers a strong basis for future clinical validation to advance precision medicine in HCC.

Role of Non-coding RNAs in the Response of Glioblastoma to Temozolomide

Chemotherapy and radiotherapy are widely used in clinical practice across the globe as cancer treatments. Intrinsic or acquired chemoresistance poses a significant problem for medical practitioners and researchers, causing tumor recurrence and metastasis. The most dangerous kind of malignant brain tumor is called glioblastoma multiforme (GBM) that often recurs following surgery. The most often used medication for treating GBM is temozolomide chemotherapy; however, most patients eventually become resistant. Researchers are studying preclinical models that accurately reflect human disease and can be used to speed up drug development to overcome chemoresistance in GBM. Non-coding RNAs (ncRNAs) have been shown to be substantial in regulating tumor development and facilitating treatment resistance in several cancers, such as GBM. In this work, we mentioned the mechanisms of how different ncRNAs (microRNAs, long non-coding RNAs, circular RNAs) can regulate temozolomide chemosensitivity in GBM. We also address the role of these ncRNAs encapsulated inside secreted exosomes.

MicroRNAs as the pivotal regulators of Temozolomide resistance in glioblastoma

Glioblastoma (GBM) is an aggressive nervous system tumor with a poor prognosis. Although, surgery, radiation therapy, and chemotherapy are the current standard protocol for GBM patients, there is still a poor prognosis in these patients. Temozolomide (TMZ) as a first-line therapeutic agent in GBM can easily cross from the blood-brain barrier to inhibit tumor cell proliferation. However, there is a high rate of TMZ resistance in GBM patients. Since, there are limited therapeutic choices for GBM patients who develop TMZ resistance; it is required to clarify the molecular mechanisms of chemo resistance to introduce the novel therapeutic targets. MicroRNAs (miRNAs) regulate chemo resistance through regulation of drug metabolism, absorption, DNA repair, apoptosis, and cell cycle. In the present review we discussed the role of miRNAs in TMZ response of GBM cells. It has been reported that miRNAs mainly induced TMZ sensitivity by regulation of signaling pathways and autophagy in GBM cells. Therefore, miRNAs can be used as the reliable diagnostic/prognostic markers in GBM patients. They can also be used as the therapeutic targets to improve the TMZ response in GBM cells.

Use of microRNAs as Diagnostic, Prognostic, and Therapeutic Tools for Glioblastoma

Glioblastoma (GB) is the most aggressive and common type of cancer within the central nervous system (CNS). Despite the vast knowledge of its physiopathology and histology, its etiology at the molecular level has not been completely understood. Thus, attaining a cure has not been possible yet and it remains one of the deadliest types of cancer. Usually, GB is diagnosed when some symptoms have already been presented by the patient. This diagnosis is commonly based on a physical exam and imaging studies, such as computed tomography (CT) and magnetic resonance imaging (MRI), together with or followed by a surgical biopsy. As these diagnostic procedures are very invasive and often result only in the confirmation of GB presence, it is necessary to develop less invasive diagnostic and prognostic tools that lead to earlier treatment to increase GB patients' quality of life. Therefore, blood-based biomarkers (BBBs) represent excellent candidates in this context. microRNAs (miRNAs) are small, non-coding RNAs that have been demonstrated to be very stable in almost all body fluids, including saliva, serum, plasma, urine, cerebrospinal fluid (CFS), semen, and breast milk. In addition, serum-circulating and exosome-contained miRNAs have been successfully used to better classify subtypes of cancer at the molecular level and make better choices regarding the best treatment for specific cases. Moreover, as miRNAs regulate multiple target genes and can also act as tumor suppressors and oncogenes, they are involved in the appearance, progression, and even chemoresistance of most tumors. Thus, in this review, we discuss how dysregulated miRNAs in GB can be used as early diagnosis and prognosis biomarkers as well as molecular markers to subclassify GB cases and provide more personalized treatments, which may have a better response against GB. In addition, we discuss the therapeutic potential of miRNAs, the current challenges to their clinical application, and future directions in the field.

Exploring signaling pathway crosstalk in glioma by mapping miRNA and WNT pathways: A review

Glioma is a significant healthcare burden; nevertheless, the particular genetic regulatory mechanism underpinning its onset and progression is still unknown. Recent research has focused in large part on trying to determine the underlying molecular pathways that contribute to the malignancy of this disease because of the difficulties in treating it. Many tumors have been linked to changes in the expression of microRNAs (miRNAs). miRNAs play a critical role in cancer development by controlling a wide variety of targets and signaling cascades. A rising body of evidence emphasizes WNT pathway dysregulation in glioma, despite the fact that it is dysregulated in many malignancies. Here, we give a detailed analysis of the roles played by miRNAs in the WNT pathway by glioma. We also demonstrate how the WNT pathway cooperates with miRNAs to control a variety of functions, including cell proliferation, invasion, migration, and epithelial-mesenchymal transition.

From resistance to resilience: Uncovering chemotherapeutic resistance mechanisms; insights from established models

Despite the tremendous advances in cancer treatment, resistance to chemotherapeutic agents impedes higher success rates and accounts for major relapses in cancer therapy. Moreover, the resistance of cancer cells to chemotherapy is linked to low efficacy and high recurrence of cancer. To stand up against chemotherapy resistance, different models of chemotherapy resistance have been established to study various molecular mechanisms of chemotherapy resistance. Consequently, this review is going to discuss different models of induction of chemotherapy resistance, highlighting the most common mechanisms of cancer resistance against different chemotherapeutic agents, including overexpression of efflux pumps, drug inactivation, epigenetic modulation, and epithelial-mesenchymal transition. This review aims to open a new avenue for researchers to lower the resistance to the existing chemotherapeutic agents, develop new therapeutic agents with low resistance potential, and establish possible prognostic markers for chemotherapy resistance.

miRNAs role in glioblastoma pathogenesis and targeted therapy: Signaling pathways interplay

High mortality and morbidity rates and variable clinical behavior are hallmarks of glioblastoma (GBM), the most common and aggressive primary malignant brain tumor. Patients with GBM often have a dismal outlook, even after undergoing surgery, postoperative radiation, and chemotherapy, which has fueled the search for specific targets to provide new insights into the development of contemporary therapies. The ability of microRNAs (miRNAs/miRs) to posttranscriptionally regulate the expression of various genes and silence many target genes involved in cell proliferation, cell cycle, apoptosis, invasion, angiogenesis, stem cell behavior and chemo- and radiotherapy resistance makes them promising candidates as prognostic biomarkers and therapeutic targets or factors to advance GBM therapeutics. Hence, this review is like a crash course in GBM and how miRNAs related to GBM. Here, we will outline the miRNAs whose role in the development of GBM has been established by recent in vitro or in vivo research. Moreover, we will provide a summary of the state of knowledge regarding oncomiRs and tumor suppressor (TS) miRNAs in relation to GBM with an emphasis on their potential applications as prognostic biomarkers and therapeutic targets.

Long non-coding RNA in glioma: novel genetic players in temozolomide resistance

Glioma is the most common primary malignant brain tumor in adults and accounts for approximately 80% of brain and central nervous system tumors. In 2021, the World Health Organization (WHO) published a new taxonomy for glioma based on its histological features and molecular alterations. Isocitrate dehydrogenase (IDH) catalyzes the decarboxylation of isocitrate, a critical metabolic reaction in energy generation in cells. Mutations in the IDH genes interrupt cell differentiation and serve as molecular biomarkers that can be used to classify gliomas. For example, the mutant IDH is widely detected in low-grade gliomas, whereas the wild type is in high-grade ones, including glioblastomas. Long non-coding RNAs (lncRNAs) are epigenetically involved in gene expression and contribute to glioma development. To investigate the potential use of lncRNAs as biomarkers, we examined lncRNA dysregulation dependent on the IDH mutation status. We found that several lncRNAs, namely, AL606760.2, H19, MALAT1, PVT1 and SBF2-AS1 may function as glioma risk factors, whereas AC068643.1, AC079228.1, DGCR5, FAM13A-AS1, HAR1A and WDFY3-AS2 may have protective effects. Notably, H19, MALAT1, PVT1, and SBF2-AS1 have been associated with temozolomide resistance in glioma patients. This review study suggests that targeting glioma-associated lncRNAs might aid the treatment of glioma.

Hippo Pathway in Regulating Drug Resistance of Glioblastoma

Glioblastoma (GBM) represents the most common and malignant tumor of the Central Nervous System (CNS), affecting both children and adults. GBM is one of the deadliest tumor types and it shows a strong multidrug resistance (MDR) and an immunosuppressive microenvironment which remain a great challenge to therapy. Due to the high recurrence of GBM after treatment, the understanding of the chemoresistance phenomenon and how to stimulate the antitumor immune response in this pathology is crucial. The deregulation of the Hippo pathway is involved in tumor genesis, chemoresistance and immunosuppressive nature of GBM. This pathway is an evolutionarily conserved signaling pathway with a kinase cascade core, which controls the translocation of YAP (Yes-Associated Protein)/TAZ (Transcriptional Co-activator with PDZ-binding Motif) into the nucleus, leading to regulation of organ size and growth. With this review, we want to highlight how chemoresistance and tumor immunosuppression work in GBM and how the Hippo pathway has a key role in them. We linger on the role of the Hippo pathway evaluating the effect of its de-regulation among different human cancers. Moreover, we consider how different pathways are cross-linked with the Hippo signaling in GBM genesis and the hypothetical mechanisms responsible for the Hippo pathway activation in GBM. Furthermore, we describe various drugs targeting the Hippo pathway. In conclusion, all the evidence described largely support a strong involvement of the Hippo pathway in gliomas progression, in the activation of chemoresistance mechanisms and in the development of an immunosuppressive microenvironment. Therefore, this pathway is a promising target for the treatment of high grade gliomas and in particular of GBM.

Regulatory interplay between microRNAs and WNT pathway in glioma

Glioma is one of the most common neoplasms of the central nervous system with a poor survival. Due to the obstacles in treating this disease, a part of recent studies mainly focuses on identifying the underlying molecular mechanisms that contribute to its malignancy. Altering microRNAs (miRNAs) expression pattern has been identified obviously in many cancers. Through regulating various targets and signaling pathways, miRNAs play a pivotal role in cancer progression. As one of the essential signaling pathways, WNT pathway is dysregulated in many cancers, and a growing body of evidence emphasis its dysregulation in glioma. Herein, we provide a comprehensive review of miRNAs involved in WNT pathway in glioma. Moreover, we show the interplay between miRNAs and WNT pathway in regulating different processes such as proliferation, invasion, migration, radio/chemotherapy resistance, and epithelial-mesenchymal-transition. Then, we introduce several drugs and treatments against glioma, which their effects are mediated through the interplay of WNT pathway and miRNAs.

Elucidating the mechanisms of Temozolomide resistance in gliomas and the strategies to overcome the resistance

Temozolomide (TMZ) is a first-choice alkylating agent inducted as a gold standard therapy for glioblastoma multiforme (GBM) and astrocytoma. A majority of patients do not respond to TMZ during the course of their treatment. Activation of DNA repair pathways is the principal mechanism for this phenomenon that detaches TMZ-induced O-6-methylguanine adducts and restores genomic integrity. Current understanding in the domain of oncology adds several other novel mechanisms of resistance such as the involvement of miRNAs, drug efflux transporters, gap junction's activity, the advent of glioma stem cells as well as upregulation of cell survival autophagy. This review describes a multifaceted account of different mechanisms responsible for the intrinsic and acquired TMZ-resistance. Here, we summarize different strategies that intensify the TMZ effect such as MGMT inhibition, development of novel imidazotetrazine analog, and combination therapy; with an aim to incorporate a successful treatment and increased overall survival in GBM patients.

The multi-target small-molecule inhibitor SB747651A shows in vitro and in vivo anticancer efficacy in glioblastomas

Glioblastoma multiforme is the most common primary brain tumor and among the most lethal types of cancer. Several mono-target small molecule-inhibitors have been investigated as novel therapeutics, thus far with poor success. In this study we investigated the anticancer effects of SB747651A, a multi-target small-molecule inhibitor, in three well characterized patient-derived glioblastoma spheroid cultures and a murine orthotopic xenograft model. Concentrations of 5–10 µM SB747651A reduced cell proliferation, spheroid formation, migration and chemoresistance, while apoptotic cell death increased. Investigation of oncogenic kinase signaling showed decreased phosphorylation levels of mTOR, CREB, GSK3 and GYS1 leading to altered glycogen metabolism and formation of intracellular reactive oxygen species. Expression levels of cancer stemness marker SOX2 were reduced in treated tumor cells and SB747651A treatment significantly prolonged survival of mice with intracranial glioblastoma xenografts, while no adverse effects were observed in vivo at doses of 25 mg/kg administered 5 days/week for 8 weeks. These findings suggest that SB747651A has anticancer effects in glioblastoma. The cancer-related pathophysiological mechanisms targeted by SB747651A are shared among many types of cancer; however, an in-depth clarification of the mechanisms of action in cancer cells is important before further potential application of SB747651A as an anticancer agent can be considered.

If Artificial In Vitro Microenvironment Can Influence Tumor Drug Resistance Network via Modulation of lncRNA Expression?-Comparative Analysis of Glioblastoma-Derived Cell Culture Models and Initial Tumors In Vivo

The tumor resistance of glioblastoma cells in vivo is thought to be enhanced by their heterogeneity and plasticity, which are extremely difficult to curb in vitro. The external microenvironment shapes the molecular profile of tumor culture models, thus influencing potential therapy response. Our study examines the expression profile of selected lncRNAs involved in tumor resistance network in three different glioblastoma-derived models commonly utilized for testing drug response in vitro. Differential expression analysis revealed significant divergence in lncRNA profile between parental tumors and tumor-derived cell cultures in vitro, including the following particles: MALAT1, CASC2, H19, TUSC7, XIST, RP11-838N2.4, DLX6-AS1, GLIDR, MIR210HG, SOX2-OT. The examined lncRNAs influence the phenomenon of tumor resistance via their downstream target genes through a variety of processes: multi-drug resistance, epithelial-mesenchymal transition, autophagy, cell proliferation and viability, and DNA repair. A comparison of in vivo and in vitro expression identified differences in the levels of potential lncRNA targets, with the highest discrepancies detected for the MDR1, LRP1, BCRP and MRP1 genes. Co-expression analyses confirmed the following interrelations: MALAT1-TYMS, MALAT1-MRP5, H19-ZEB1, CASC2-VIM, CASC2-N-CAD; they additionally suggest the possibility of MALAT1-BCRP, MALAT1-mTOR and TUSC7-PTEN interconnections in glioblastoma. Although our results clearly demonstrate that the artificial ex vivo microenvironment changes the profile of lncRNAs related to tumor resistance, it is difficult to anticipate the final phenotypic effect, since this phenomenon is a complex one that involves a network of molecular interactions underlying a variety of cellular processes.

miRNA signature in glioblastoma: Potential biomarkers and therapeutic targets

MicroRNAs (miRNAs) are transcripts with sizes of about 22 nucleotides, which are produced through a multistep process in the nucleus and cytoplasm. These transcripts modulate the expression of their target genes through binding with certain target regions, particularly 3' suntranslated regions. They are involved in the pathogenesis of several kinds of cancers, such as glioblastoma. Several miRNAs, including miR-10b, miR-21, miR-17-92-cluster, and miR-93, have been up-regulated in glioblastoma cell lines and clinical samples. On the other hand, expression of miR-7, miR-29b, miR-32, miR-34, miR-181 family members, and a number of other miRNAs have been decreased in this type of cancer. In the current review, we explain the role of miRNAs in the pathogenesis of glioblastoma through providing a summary of studies that reported dysregulation of these epigenetic effectors in this kind of brain cancer.

Phospholipase D1 inhibition sensitizes glioblastoma to temozolomide and suppresses its tumorigenicity

Resistance of glioblastoma to the chemotherapeutic compound temozolomide is associated with the presence of glioblastoma stem cells in glioblastoma and is a key obstacle for the poor prognosis of glioblastoma. Here, we show that phospholipase D1 is elevated in CD44^High glioblastoma stem cells and in glioblastoma, especially recurring glioblastoma. Phospholipase D1 elevation positively correlated with the level of CD44 and poor prognosis in glioblastoma patients. Temozolomide significantly upregulated the expression of phospholipase D1 in the low and moderate CD44 populations of glioblastoma stem cells, but not in the CD44^High population in which phospholipase D1 is highly expressed. Phospholipase D1 conferred resistance to temozolomide in CD44^High glioblastoma stem cells and increased their self‐renewal capacity and maintenance. Phospholipase D1 expression significantly correlated with levels of temozolomide resistance factors, which were suppressed by microRNA‐320a and ‐4496 induced by phospholipase D1 inhibition. Genetic and pharmacological targeting of phospholipase D1 attenuated glioblastoma stem cell‐derived intracranial tumors of glioblastoma using the microRNAs, and improved survival. Treatment solely with temozolomide produced no benefits on the glioblastoma, whereas in combination, phospholipase D1 inhibition sensitized glioblastoma stem cells to temozolomide and reduced glioblastoma tumorigenesis. Together, these findings indicate that phospholipase D1 inhibition might overcome resistance to temozolomide and represents a potential treatment strategy for glioblastoma. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Molecular and Cellular Complexity of Glioma. Focus on Tumour Microenvironment and the Use of Molecular and Imaging Biomarkers to Overcome Treatment Resistance

This review highlights the importance and the complexity of tumour biology and microenvironment in the progression and therapy resistance of glioma. Specific gene mutations, the possible functions of several non-coding microRNAs and the intra-tumour and inter-tumour heterogeneity of cell types contribute to limit the efficacy of the actual therapeutic options. In this scenario, identification of molecular biomarkers of response and the use of multimodal in vivo imaging and in particular the Positron Emission Tomography (PET) based molecular approach, can help identifying glioma features and the modifications occurring during therapy at a regional level. Indeed, a better understanding of tumor heterogeneity and the development of diagnostic procedures can favor the identification of a cluster of patients for personalized medicine in order to improve the survival and their quality of life.

Extending Arms of Insulin Resistance from Diabetes to Alzheimer's Disease: Identification of Potential Therapeutic Targets

BACKGROUND & OBJECTIVE

Type 3 diabetes (T3D) is chronic insulin resistant state of brain which shares pathology with sporadic Alzheimer's disease (sAD). Insulin signaling is a highly conserved pathway in the living systems that orchestrate cell growth, repair, maintenance, energy homeostasis and reproduction. Although insulin is primarily studied as a key molecule in diabetes mellitus, its role has recently been implicated in the development of Alzheimer's disease (AD). Severe complications in brain of diabetic patients and metabolically compromised status is evident in brain of AD patients. Underlying shared pathology of two disorders draws a trajectory from peripheral insulin resistance to insulin unresponsiveness in the central nervous system (CNS). As insulin has a pivotal role in AD, it is not an overreach to address diabetic condition in AD brain as T3D. Insulin signaling is indispensable to nervous system and it is vital for neuronal growth, repair, and maintenance of chemical milieu at synapses. Downstream mediators of insulin signaling pathway work as a regulatory hub for aggregation and clearance of unfolded proteins like Aβ and tau.

CONCLUSION

In this review, we discuss the regulatory roles of insulin as a pivotal molecule in brain with the understanding of defective insulin signaling as a key pathological mechanism in sAD. This article also highlights ongoing trials of targeting insulin signaling as a therapeutic manifestation to treat diabetic condition in brain.

miR-101-3p sensitizes non-small cell lung cancer cells to irradiation

Recent studies have revealed that microRNAs regulate radiosensitivity of non-small cell lung cancer (NSCLC). The aim of this study was to investigate whether miR-101-3p is correlated with radiosensitivity of NSCLC. According to our results, miR-101-3p was downregulated in NSCLC tissues and cell lines. Moreover, miR-101-3p was decreased in A549 cells' response to irradiation in a dose-dependent manner. Upregulation of miR-101-3p decreased survival fraction and colony formation rate and increased irradiation-induced apoptosis in irradiation-resistant cells, while miR-101-3p depletion had the opposite effects in irradiation-sensitive cells. Furthermore, mechanistic target of rapamycin (mTOR) is a target gene of miR-101-3p. The expressions of mTOR, p-mTOR, and p-S6 were curbed by overexpression of miR-101-3p in A549R cells, which was enhanced by repression of miR-101-3p in A549 cells. Intriguingly, elevation in mTOR abated miR-101-3p upregulation-induced increase in irradiation sensitivity in irradiation-resistant cell line. In contrast, rapamycin undermined miR-101-3p inhibitor-mediated reduction of irradiation sensitivity in irradiation-sensitive cell line. Besides, miR-101-3p overexpression enhanced the efficacy of radiation in an NSCLC xenograft mouse model. In conclusion, miR-101-3p sensitized A549 cells to irradiation via inhibition of mTOR-signaling pathway.

Targeting GSK3 and Associated Signaling Pathways Involved in Cancer

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine (S/T) protein kinase. Although GSK-3 originally was identified to have functions in regulation of glycogen synthase, it was subsequently determined to have roles in multiple normal biochemical processes as well as various disease conditions. GSK-3 is sometimes referred to as a moonlighting protein due to the multiple substrates and processes which it controls. Frequently, when GSK-3 phosphorylates proteins, they are targeted for degradation. GSK-3 is often considered a component of the PI3K/PTEN/AKT/GSK-3/mTORC1 pathway as GSK-3 is frequently phosphorylated by AKT which regulates its inactivation. AKT is often active in human cancer and hence, GSK-3 is often inactivated. Moreover, GSK-3 also interacts with WNT/β-catenin signaling and β-catenin and other proteins in this pathway are targets of GSK-3. GSK-3 can modify NF-κB activity which is often expressed at high levels in cancer cells. Multiple pharmaceutical companies developed small molecule inhibitors to suppress GSK-3 activity. In addition, various natural products will modify GSK-3 activity. This review will focus on the effects of small molecule inhibitors and natural products on GSK-3 activity and provide examples where these compounds were effective in suppressing cancer growth.

GSK3 and miRNA in neural tissue: From brain development to neurodegenerative diseases

MicroRNAs (miRs) are small RNAs modulating gene expression and creating intricate regulatory networks that are dysregulated in many pathological states, including neurodegenerative disorders. In silico analyses denote a multifunctional kinase glycogen synthase kinase-3 (GSK3) as a putative target of numerous miRs identified in neural tissue. GSK3 is engaged in almost all aspects of neuronal development and functioning. Moreover, there is an autoregulatory feedback between GSK3 and miRNAs as the kinase can influence biogenesis of miRs. Members of the miR-GSK3 axes might thus represent convenient therapeutic targets in neuropathologies that display its abnormal regulation. This review summarizes the present knowledge about direct interactions of GSK3 and miRs in brain, and their putative roles in pathogenesis of neurodegenerative and neuropsychiatric disorders. This article is part of a Special Issue entitled: GSK-3 and related kinases in cancer, neurological and other disorders edited by James McCubrey, Agnieszka Gizak and Dariusz Rakus.

Micro RNA Molecules as Modulators of Treatment Resistance, Immune Checkpoints Controllers and Sensitive Biomarkers in Glioblastoma Multiforme

Based on genome sequencing, it is estimated that over 90% of genes stored in human genetic material are transcribed, but only 3% of them contain the information needed for the production of body proteins. This group also includes micro RNAs representing about 1%–3% of the human genome. Recent studies confirmed the hypothesis that targeting molecules called Immune Checkpoint (IC) open new opportunities to take control over glioblastoma multiforme (GBM). Detection of markers that indicate the presence of the cancer occupies a very important place in modern oncology. This function can be performed by both the cancer cells themselves as well as their components and other substances detected in the patients’ bodies. Efforts have been made for many years to find a suitable marker useful in the diagnosis and monitoring of gliomas, including glioblastoma.

GSK-3β in DNA repair, apoptosis, and resistance of chemotherapy, radiotherapy of cancer

Glycogen synthase kinase-3β (GSK-3β) is an evolutionarily conserved serine/threonine kinase, functioning in numerous cellular processes including cell proliferation, DNA repair, cell cycle, signaling and metabolic pathways. GSK-3β is implicated in different diseases including inflammation, neurodegenerative disease, diabetes and cancers. GSK-3β is involved in biological processes of tumorigenesis, therefore, it is rational that GSK-3β inhibitors were employed to target malignant tumors. The effects of GSK-3β inhibitors in combination of radiation and chemotherapeutic drugs have been reported in various types of cancers, suggesting GSK-3β would play important roles in cancer treatments. GSK-3β is involved in multiple signal pathway including Wnt/β-catenin, PI3K/PTEN/AKT and Notch. GSK-3β also functions in DNA repair through phosphorylation of DNA repair factors and affecting their binding to chromatin. This review focuses on the molecular mechanism of GSK-3β in DNA repair, special in base excision repair and double-strands break repair, the roles of GSK-3β in inhibition of apoptosis through activation of NF-κB, and the effects of GSK-3β inhibitors on radio- and chemosensitization of various types of cancers. This article is part of a Special Issue entitled: GSK-3 and related kinases in cancer, neurological and other disorders edited by James McCubrey, Agnieszka Gizak and Dariusz Rakus.

Repression of PCGF1 Decreases the Proliferation of Glioblastoma Cells in Association with Inactivation of c-Myc Signaling Pathway

Purpose

Glioblastoma (GBM) is the most common primary brain tumor with a poor therapeutic outcome. Polycomb group factor 1 (PCGF1), a member of the PcG (Polycomb group) family, is highly expressed in the developing nervous system of mice. However, the function and the mechanism of PCGF1 in GBM proliferation still remain unclear.

Methods

Knockdown of PCGF1 was performed in U87 GBM cell by shRNA strategy via lentivirus vector. MTT assay, colony formation assays, and flow cytometry were used to measure the properties of cell proliferation and cell cycle distribution, respectively. GeneChip analysis was performed to identify the downstream effector molecules. Rescue assay was constructed to verify the screening results.

Results

We first found that knockdown of PCGF1 led to the inhibition of U87 cells proliferation and decreased colony formation ability. The data from GeneChip expression profiling and Ingenuity Pathway Analysis (IPA) indicated that many of the altered gene cells are associated with the cell proliferation control pathways. We have further confirmed the suppression of AKT/GSK3β/c-Myc/cyclinD1 expressions by Western blotting analysis. The over-expression of c-Myc could partly restore the attenuated proliferation ability caused by knockdown of PCGF1.

Conclusion

All the above evidences suggested that PCGF1 might be closely associated with tumorigenesis and progression of glioblastoma (GBM), in which process the oncoprotein c-Myc may participate. PCGF1 could thus be a potential therapeutic target for the treatment of glioblastoma (GBM).

Antagonism between the RNA-binding protein Musashi1 and miR-137 and its potential impact on neurogenesis and glioblastoma development

RNA-binding proteins (RBPs) and miRNAs are critical gene expression regulators that interact with one another in cooperative and antagonistic fashions. We identified Musashi1 (Msi1) and miR-137 as regulators of a molecular switch between self-renewal and differentiation. Msi1 and miR-137 have opposite expression patterns and functions, and Msi1 is repressed by miR-137. Msi1 is a stem-cell protein implicated in self-renewal while miR-137 functions as a proneuronal differentiation miRNA. In gliomas, miR-137 functions as a tumor suppressor while Msi1 is a prooncogenic factor. We suggest that the balance between Msi1 and miR-137 is a key determinant in cell fate decisions and disruption of this balance could contribute to neurodegenerative diseases and glioma development. Genomic analyses revealed that Msi1 and miR-137 share 141 target genes associated with differentiation, development, and morphogenesis. Initial results pointed out that these two regulators have an opposite impact on the expression of their target genes. Therefore, we propose an antagonistic model in which this network of shared targets could be either repressed by miR-137 or activated by Msi1, leading to different outcomes (self-renewal, proliferation, tumorigenesis).

Endoplasmic reticulum and the microRNA environment in the cardiovascular system 1

Stress responses are important to human physiology and pathology, and the inability to adapt to cellular stress leads to cell death. To mitigate cellular stress and re-establish homeostasis, cells, including those in the cardiovascular system, activate stress coping response mechanisms. The endoplasmic reticulum, a component of the cellular reticular network in cardiac cells, mobilizes so-called endoplasmic reticulum stress coping responses, such as the unfolded protein response. MicroRNAs play an important part in the maintenance of cellular and tissue homeostasis, perform a central role in the biology of the cardiac myocyte, and are involved in pathological cardiac function and remodeling. In this paper, we review a link between endoplasmic reticulum homeostasis and microRNA with an emphasis on the impact on stress responses in the cardiovascular system.

LncRNA Rik-203 contributes to anesthesia neurotoxicity via microRNA-101a-3p and GSK-3β-mediated neural differentiation

The mechanism of anesthesia neurotoxicity remains largely to be determined. The effects of long noncoding RNAs (LncRNAs) on neural differentiation and the underlying mechanisms are unknown. We thus identified LncRNA Rik-203 (C130071C03Rik) and studied its role on neural differentiation and its interactions with anesthetic sevoflurane, miRNA and GSK-3β. We found that levels of Rik-203 were higher in hippocampus than other tissues and increased during neural differentiation. Sevoflurane decreased the levels of Rik-203. Rik-203 knockdown reduced mRNA levels of Sox1 and Nestin, the markers of neural progenitor cells, and decreased the count of Sox1 positive cells. RNA-RNA pull-down showed that miR-101a-3p was highly bound to Rik-203. Finally, sevoflurane, knockdown of Rik-203, and miR-101a-3p overexpression all decreased GSK-3β levels. These data suggest that Rik-203 facilitates neural differentiation by inhibiting miR-101a-3p's ability to reduce GSK-3β levels and that LncRNAs would serve as the mechanism of the anesthesia neurotoxicity.

Alkylating anticancer agents and their relations to microRNAs

Alkylating agents represent an important class of anticancer drugs. The occurrence and emergence of tumor resistance to the treatment with alkylating agents denotes a severe problem in the clinics. A detailed understanding of the mechanisms of activity of alkylating drugs is essential in order to overcome drug resistance. In particular, the role of non-coding microRNAs concerning alkylating drug activity and resistance in various cancers is highlighted in this review. Both synthetic and natural alkylating agents, which are approved for cancer therapy, are discussed concerning their interplay with microRNAs.

The proliferation and invasion of osteosarcoma are inhibited by miR-101 via targetting ZEB2

Having a better grasp of the molecular mechanisms underlying carcinogenesis and progression in osteosarcoma would be helpful to find novel therapeutic targets. Different types of cancers have presented abnormal expression of miRNA-101 (miR-101). Nevertheless, we still could not figure out what expression of miR-101 in human osteosarcoma is and its biological function. Thus, we conducted the present study to identify its expression, function, and molecular mechanism in osteosarcoma. We detected the expression of miR-101 in osteosarcoma samples and cell lines. The effects of miR-101 on osteosarcoma cells’ proliferation and invasion were evaluated. Luciferase reporter assay was applied to identify the direct target of miR-101. Compared with adjacent normal specimens and normal bone cell line by using qPCR, the expression levels of miR-101 in osteosarcoma specimens and human osteosarcoma cell lines distinctly decreased. According to function assays, we found that overexpression of miR-101 significantly inhibited the cell proliferation and invasion in osteosarcoma cells. Moreover, we confirmed that zinc finger E-box binding homeobox 2 (ZEB2) was a direct target of miR-101. In addition, overexpression of ZEB2 could rescue the inhibition effect of proliferation and invasion induced by miR-101 in osteosarcoma cells. MiR-101 has been proved to be down-regulated in osteosarcoma and has the ability to suppress osteosarcoma cell proliferation and invasion by directly targetting ZEB2.

MiR-101-3p inhibits EMT to attenuate proliferation and metastasis in glioblastoma by targeting TRIM44

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor originating in the brain parenchyma. The invasive and infiltrative properties of glioblastoma result in poor clinical prognosis to conventional therapies. Emerging reports on microRNAs as important regulators during the process of EMT provide new insights into treating glioblastoma through new targets. However, underlying molecular mechanism of the regulation of miR-101-3p in glioblastoma remains unclear.

METHODS

Level of miR-101-3p was determined in GBM cell lines by qRT-PCR. MTT, colony formation and transwell assays were utilized to evaluate functions of overexpression of miR-101-3p/knock down of TRIM44 on proliferation, migration and invasion in GBM cells. Direct interaction between miR-101-3p and TRIM44 was validated using dual luciferase reporter system and impacts of overexpression of miR-101-3p/knock down of TRIM44 on regulation of EMT markers were assessed by Western blotting.

RESULTS

MiR-101-3p was validated to be repressed expressed in glioblastoma cancer cell lines. Both overexpression of miR-101-3p and knock down of TRIM44 attenuated proliferation, migration and invasion of glioblastoma cell lines in vitro. TRIM44 was shown to promote EMT in GBM progress and reverse inhibitory function of miR-101-3p. MiR-101-3p was found to suppress the expression of TRIM44 via directly targeting its 3'UTR.

CONCLUSIONS

Our findings suggested miR-101-3p regulated proliferation and migration of glioblastoma cells through attenuating TRIM44 induced EMT via direct targeting 3'UTR of TRIM44, which provided preliminary study of potential therapeutic target in future GBM treatment.

Non-Coding RNAs in Glioma

Glioma is the most aggressive brain tumor of the central nervous system. The ability of glioma cells to migrate, rapidly diffuse and invade normal adjacent tissue, their sustained proliferation, and heterogeneity contribute to an overall survival of approximately 15 months for most patients with high grade glioma. Numerous studies indicate that non-coding RNA species have critical functions across biological processes that regulate glioma initiation and progression. Recently, new data emerged, which shows that the cross-regulation between long non-coding RNAs and small non-coding RNAs contribute to phenotypic diversity of glioblastoma subclasses. In this paper, we review data of long non-coding RNA expression, which was evaluated in human glioma tissue samples during a five-year period. Thus, this review summarizes the following: (I) the role of non-coding RNAs in glioblastoma pathogenesis, (II) the potential application of non-coding RNA species in glioma-grading, (III) crosstalk between lncRNAs and miRNAs (IV) future perspectives of non-coding RNAs as biomarkers for glioma.

MiR-101: a potential therapeutic target of cancers

MicroRNAs (miRNAs) are small noncoding RNAs that could regulate gene expressions transcriptionally or post-transcriptionally through binding to 3' untranslated region (3'UTR) of target messenger RNAs (mRNAs), which were identified to be associated with tumorigenesis in various neoplasms. Among them, miR-101, encoded by two precursor transcripts (miR-101-1 and miR-101-2), was recognized to serve as a tumor suppressor via targeting critical oncogenes or anti-oncogenes. Additionally, studies have shown that miR-101 was participated in multiple cancer-related biological processes, including proliferation, apoptosis, angiogenesis, drug resistance, invasion and metastasis. In this review, we aim to summarize the function of miR-101 in different biological processes by figuring out the underlying target gene networks and explore its potential role as a biomarker in diverse neoplasms, which will provide a brand-new insight in molecular targeting cancer treatment.

Potential Strategies Overcoming the Temozolomide Resistance for Glioblastoma

Glioblastoma (GBM) is a highly malignant type of primary brain tumor with a high mortality rate. Although the current standard therapy consists of surgery followed by radiation and temozolomide (TMZ), chemotherapy can extend patient's post-operative survival but most cases eventually demonstrate resistance to TMZ. O6-methylguanine-DNA methyltransferase (MGMT) repairs the main cytotoxic lesion, as O6-methylguanine, generated by TMZ, can be the main mechanism of the drug resistance. In addition, mismatch repair and BER also contribute to TMZ resistance. TMZ treatment can induce self-protective autophagy, a mechanism by which tumor cells resist TMZ treatment. Emerging evidence also demonstrated that a small population of cells expressing stem cell markers, also identified as GBM stem cells (GSCs), contributes to drug resistance and tumor recurrence owing to their ability for self-renewal and invasion into neighboring tissue. Some molecules maintain stem cell properties. Other molecules or signaling pathways regulate stemness and influence MGMT activity, making these GCSs attractive therapeutic targets. Treatments targeting these molecules and pathways result in suppression of GSCs stemness and, in highly resistant cases, a decrease in MGMT activity. Recently, some novel therapeutic strategies, targeted molecules, immunotherapies, and microRNAs have provided new potential treatments for highly resistant GBM cases. In this review, we summarize the current knowledge of different resistance mechanisms, novel strategies for enhancing the effect of TMZ, and emerging therapeutic approaches to eliminate GSCs, all with the aim to produce a successful GBM treatment and discuss future directions for basic and clinical research to achieve this end.

Glioblastoma Chemoresistance: The Double Play by Microenvironment and Blood-Brain Barrier

For glioblastoma, the tumor microenvironment (TME) is pivotal to support tumor progression and therapeutic resistance. TME consists of several types of stromal, endothelial and immune cells, which are recruited by cancer stem cells (CSCs) to influence CSC phenotype and behavior. TME also promotes the establishment of specific conditions such as hypoxia and acidosis, which play a critical role in glioblastoma chemoresistance, interfering with angiogenesis, apoptosis, DNA repair, oxidative stress, immune escape, expression and activity of multi-drug resistance (MDR)-related genes. Finally, the blood brain barrier (BBB), which insulates the brain microenvironment from the blood, is strongly linked to the drug-resistant phenotype of glioblastoma, being a major physical and physiological hurdle for the delivery of chemotherapy agents into the brain. Here, we review the features of the glioblastoma microenvironment, focusing on their involvement in the phenomenon of chemoresistance; we also summarize recent advances in generating systems to modulate or bypass the BBB for drug delivery into the brain. Genetic aspects associated with glioblastoma chemoresistance and current immune-based strategies, such as checkpoint inhibitor therapy, are described too.

miR‑501‑3p sensitizes glioma cells to cisplatin by targeting MYCN

Cisplatin, a commonly used chemotherapeutic agent for glioma patients, treatment often leads to chemoresistance. Accumulating evidence has demosntrated that microRNA (miRNA/miR) is involved in drug resistance of glioma cells. Nevertheless, the role of miR‑501‑3p in glioma cell resistance to cisplatin is unclear. In the present study, it was revealed that miR‑501‑3p expression was decreased in glioma tissues and further underexpressed in cisplatin‑resistant glioma cells compared with wild‑type (WT) glioma cells. Furthermore, cisplatin treatment inhibited the level of miR‑501‑3p in a time‑dependent way. Ectopic expression of miR‑501‑3p suppressed glioma cell growth and invasion, but increased cisplatin‑resistant glioma cell apoptosis. Furthermore, miR‑501‑3p sensitized glioma cells to cisplatin‑induced proliferation arrest and death. Mechanistically, it was demonstrated that miR‑501‑3p targeted MYCN in glioma cells. In addition, it was revealed that miR‑501‑3p inhibited MYCN expression by a luciferase reporter assay and reverse transcription‑quantitative polymerase chain reaction. Notably, restoration of MYCN reversed the effects of miR‑501‑3p in cisplatin‑resistant glioma cells. In conclusion, these results suggested that miR‑501‑3p may serve a promising marker for cisplatin resistance.

Aberrant miRNAs Regulate the Biological Hallmarks of Glioblastoma

GBM is the highest incidence in primary intracranial malignancy, and it remains poor prognosis even though the patient is gave standard treatment. Despite decades of intense research, the complex biology of GBM remains elusive. In view of eight hallmarks of cancer which were proposed in 2011, studies related to the eight biological capabilities in GBM have made great progress. From these studies, it can be inferred that miRs, as a mode of post-transcriptional regulation, are involved in regulating these malignant biological hallmarks of GBM. Herein, we discuss state-of-the-art research on how aberrant miRs modulate the eight hallmarks of GBM. The upregulation of 'oncomiRs' or the genetic loss of tumor suppressor miRs is associated with these eight biological capabilities acquired during GBM formation. Furthermore, we also discuss the applicable clinical potential of these research results. MiRs may aid in the diagnosis and prognosis of GBM. Moreover, miRs are also therapeutic targets of GBM. These studies will develop and improve precision medicine for GBM in the future.

Long noncoding RNA MALAT1 knockdown reverses chemoresistance to temozolomide via promoting microRNA-101 in glioblastoma

Glioblastoma (GBM) is the most common and lethal tumor of the central nervous system with highly infiltrative and resistant to chemotherapy. Temozolomide (TMZ) is widely used as the first-line treatment for the therapy of GBM. However, a considerable percentage inherent or acquired resistance in GBM accounts for many treatment failures of the TMZ chemotherapy. Therefore, a deeper understanding of the molecular characteristics underlying TMZ resistance and the identification of novel therapeutic target is urgent. Here, we show that MALAT1 was significantly upregulated in TMZ-resistant GBM cells. On the other hand, MALAT1 knockdown reduces TMZ resistance of GBM cells both in vitro and in vivo by inhibiting cell proliferation and promoting apoptosis. We also show that miR-101 overexpression reduced TMZ resistance of GBM cells and played an antagonistic role compared with MALAT1. Importantly, we demonstrate that MALAT1 promoted the chemoresistance through suppressing miR-101 signaling pathway via directly binding it in GBM cells. In conclusion, our study indicates that knockdown of MALAT1 reverses chemoresistance to TMZ via promoting miR-101 regulatory network in GBM and thus offers a novel prognostic marker and potential target for GBM TMZ-based chemotherapy.

Glioblastoma research: US and international networking achievements

Being the most aggressive type of brain tumor, glioblastoma is estimated to be diagnosed in about 12,400 new cases in 2017. The diagnosis is dramatic to patients and relatives and leaves open many unanswered questions for them. One is the big question why there is no cure as in other tumors. This review illustrates the US and global research efforts that have been made over the past century. It demonstrates the great magnitude of energy invested by US clinicians and scientists but undoubtedly, more research is needed and funding by NIH and other sources should be continued on the same level.

Prognostic significance of microRNA-101 in solid tumor: A meta-analysis

MicroRNA-101 has been reported as an important factor in carcinogenesis of several malignant tumors. However, its actual role in prognosis among solid malignancies remains unclear. Accordingly, we performed this meta-analysis aiming to identify prognostic significance of miR-101 in solid tumor. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS) or disease-free survival (DFS)/metastasis-free survival (MFS)/progression-free survival (PFS)/relapse-free survival (RFS)/time-to progression (TTP) were estimated with random effects or fixed effects models on the basis of heterogeneity. Subgroup analysis, sensitive analysis and meta-regression analysis were also conducted to clarify the possible confounding factors and investigate the source of heterogeneity. Publication bias was evaluated by using Begg’s and Egger’s tests. A total of 21 studies containing 3753 cases were selected into our quantitative analysis via electronic database search. A lower expression of miR-101 was significantly associated with worse OS (HR = 0.66, 95%CI [0.52–0.85], P = 0.001) and PFS (HR = 0.70, 95%CI [0.51–0.95], P = 0.023) in patients with solid tumor. The under-expression of miRNA-101 is a credible indicator of poorer prognosis in several of solid malignancies.

The prognostic value of decreased miR-101 in various cancers: a meta-analysis of 12 studies

BACKGROUND

A consensus regarding the prognostic value of decreased miR-101 in human cancers has not been reached. This study aimed to comprehensively investigate the internal associations between loss of miR-101 expression and prognostic implications in patients with cancer.

MATERIALS AND METHODS

All relevant literature in electronic databases, including PubMed, ISI Web of Science, and Embase, up to March 1, 2017 were searched. Correlations between decreased miR-101 and clinicopathological parameters were defined by odds ratios (ORs). The degree of association between reduced miR-101 and survival outcome was evaluated by pooled hazard ratios (HRs) and relevant 95% CIs.

RESULTS

Twelve eligible studies with 2,088 patients were included in this meta-analysis. Decreased miR-101 expression was closely connected with poor overall survival, with a pooled HR of 2.15 (95% CI 1.71-2.7, P<0.001). This correlation was also revealed when stratified analysis was conducted with respect to ethnicity, cancer type, sample size, specimen source, and analysis model. However, decreased miR-101 was not associated with disease-free survival, recurrence-free survival, or progression-free survival, with a pooled HR of 1.59 (95% CI 0.83-3.03, P=0.128), despite a positive trend. In addition, reduced miR-101 was intimately related to poorer tumor differentiation (OR 2.17, 95% CI 1.14-4.13; P=0.019), advanced tumor classification (OR 5.25, 95% CI 3.39-8.12; P<0.001), and higher TNM stage (OR 6.18, 95% CI 3.79-10.09; P<0.001).

CONCLUSION

Our findings suggest that loss of miR-101 expression is correlated with worse overall survival in a variety of cancers, and could serve as a predictive indicator for clinicopathological features. Furthermore, miR-101 may become a feasible therapeutic target in most human cancers.

miR-101 alleviates chemoresistance of gastric cancer cells by targeting ANXA2

BACKGROUND

Chemoresistance remains a main clinical obstacle in the treatment of gastric cancer (GC). microRNAs have been revealed to participate in the regulation of drug resistance in a variety of cancers. However, little is known about the function and detailed molecular mechanism of miR-101 in GC chemoresistance.

METHODS

The expressions of miR-101 and Annexin A2 (ANXA2) in GC tissues and cells were detected by qRT-PCR and western blot. The effects of miR-101 overexpression on P-glycoprotein (P-gp) at mRNA and protein levels, cell viability, and apoptosis in drug-resistant GC cells were examined by qRT-PCR, western blot, MTT and flow cytometry analysis, respectively. Luciferase reporter assay, RNA immunoprecipitation (RIP) and qRT-PCR were applied to confirm whether miR-101 could target ANXA2 and regulate its expression. Rescue experiment was performed to verify the mechanism by which miR-101 involved in chemoresistance.

RESULTS

miR-101 was downregulated in GC tissues and drug-resistant GC cells. A negative correlation between miR-101 and ANXA2 expression was observed in GC tissues. Forced expression of miR-101 significantly reduced P-gp expression at mRNA and protein levels in drug-resistant GC cells. Overexpression of miR-101 enhanced sensitivity to cisplatin (DDP) or vincristine (VCR) via viability inhibition and apoptosis promotion. ANXA2 was identified as a direct target of miR-101 and miR-101 negatively regulated ANXA2 expression. Moreover, ectopic expression of ANXA2 reversed the effect of miR-101 on P-gp expression, cell viability and apoptosis.

CONCLUSION

miR-101 alleviated chemoresistance of gastric cancer cells by targeting ANXA2. Therefore, targeting miR-101 may be a potential therapeutic approach for drug-resistant GC.