MicroRNA-142-3p is involved in regulation of MGMT expression in glioblastoma 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.

The Versatile Attributes of MGMT: Its Repair Mechanism, Crosstalk with Other DNA Repair Pathways, and Its Role in Cancer

O6-methylguanine-DNA methyltransferase (MGMT or AGT) is a DNA repair protein with the capability to remove alkyl groups from O6-AlkylG adducts. Moreover, MGMT plays a crucial role in repairing DNA damage induced by methylating agents like temozolomide and chloroethylating agents such as carmustine, and thereby contributes to chemotherapeutic resistance when these agents are used. This review delves into the structural roles and repair mechanisms of MGMT, with emphasis on the potential structural and functional roles of the N-terminal domain of MGMT. It also explores the development of cancer therapeutic strategies that target MGMT. Finally, it discusses the intriguing crosstalk between MGMT and other DNA repair pathways.

miRNA-142-3p functions as a potential tumor suppressor directly targeting FAM83D in the development of ovarian cancer

Background: FAM83D (family with sequence similarity 83, member D) is of particular interest in tumorigenesis and tumor progression. Ovarian cancer is the leading cause of cancer-related death in women all over the world. This study aims to research the association between FAM83D and ovarian cancer (OC).

Methods: The gene expression data of OC and normal samples (GSE81873 and GSE27651) was downloaded from Gene Expression Omnibus (GEO) dataset. The bioinformatics analysis was performed to distinguish two differentially expressed genes (DEGs), prognostic candidate genes and functional enrichment pathways. Immunohistochemistry (IHC), Quantitative Real-time PCR (qPCR), and luciferase reporter assays were utilized for further study.

Results: There were 56 DEMs and 63 DEGs in cancer tissues compared to normal tissues. According to the km-plot software, hsa-miR-142-3p and FAM83D were associated with the overall survival of patients with OC. Besides, Multivariate analysis included that hsa-miR-142-3p and FAM83D were independent risk factors for OC patients. Furthermore, qPCR demonstrated that miRNA-142-3p and FAM83D were differentially expressed in normal ovarian tissues (NOTs) and ovarian cancer tissues (OCTs). IHC results indicated that FAM83D was overexpressed in OCTs compared with NOTs. Last but not least, luciferase reporter assays verified that FAM83D was a direct target of hsa-miRNA-142-3p in OC cells.

Conclusions: The prognostic model based on the miRNA-mRNA network could provide predictive significance for the prognosis of OC patients, which would be worthy of clinical application. Our results concluded that miR-142-3p and its targets gene FAM83D may be potential diagnostic and prognostic biomarkers for patients with OC.

Recent Development in NKT-Based Immunotherapy of Glioblastoma: From Bench to Bedside

Glioblastoma multiforme (GBM) is an aggressive and dismal disease with a median overall survival of around 15 months and a 5-year survival rate of 7.2%. Owing to genetic mutations, drug resistance, disruption to the blood–brain barrier (BBB)/blood–brain tumor barrier (BBTB), and the complexity of the immunosuppressive environment, the therapeutic approaches to GBM represent still major challenges. Conventional therapies, including surgery, radiotherapy, and standard chemotherapy with temozolomide, have not resulted in satisfactory improvements in the overall survival of GBM patients. Among cancer immunotherapeutic approaches, we propose that adjuvant NKT immunotherapy with invariant NKT (iNKT) and cytokine-induced killer (CIK) cells may improve the clinical scenario of this devastating disease. Considering this, herein, we discuss the current strategies of NKT therapy for GBM based primarily on in vitro/in vivo experiments, clinical trials, and the combinatorial approaches with future therapeutic potential.

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.

Propolis Extract Regulate microRNA Expression in Glioblastoma and Brain Cancer Stem Cells

BACKGROUND

Grade IV gliomas are classified as glioblastoma (GBM), which is the most malignant brain cancer type. Various genetic and epigenetic mechanisms play a role in the initiation and progression of GBM. MicroRNAs (miRNAs) are small, non-coding RNA molecules that are the main epigenetic regulatory RNA class. They play variable roles in both physiological and pathological conditions, including GBM pathogenesis, by regulating expression levels of the target genes. Brain cancer stem cells (BCSCs) are subpopulations of brain cancer mass that are responsible for poor prognosis, including therapy resistance and relapse. Epigenetic regulation mediated by miRNAs is also a critical component of BCSC self-renewal and differentiation properties. Propolis is a resinous substance that is collected by honey bees from various plant sources. The flavonoids content of propolis varies, depending on the region collected andthe extraction method. Although the effects of propolis that have been collected from different sources on the miRNA expression levels in the glioblastoma cells have been shown, the effects on the BCSCs are not known yet.

OBJECTIVE

The aim of this study is to evaluate the effects of Aydın, a city in western Turkey, propolis, on miRNA expression levels of BCSCs and GBM cells.

METHODS

Aydin propolis was dissolved in 60% ethanol, and after evaporation, distilled water was added to prepare the propolis stock solution. The flavonoids content of the Aydin propolis was determined by MS Q-TOF analysis. Commercially obtained U87MG, GBM cell line, and BCSCs were used as in vitro brain cancer models. The cytotoxic and apoptotic effects of Aydın propolis were determined via WST-1 assay and Annexin V test, respectively. The miRNA expression profile was investigated via the real-time qRT-PCR method, and fold changes were calculated by using the 2-^∆∆Ct method compared to untreated control cells. The miRNA-mRNA-pathway interactions, including significantly altered miRNAs, were determined using different bioinformatics tools and databases.

RESULTS

Quercetin 3-methyl ether was determined as the major component of the Aydin propolis. Aydin propolis did not show significant cytotoxic and apoptotic effects on both GBM and BCSCs up to 2mg/ml concentration. Aydin propolis treatment decreased the expression of nine and five miRNAs in the U87MG 2.13 to 5.65 folds and BCSCs 2.02 to 12.29 folds, respectively. Moreover, 10 miRNAs 2.22 to 10.56 folds were upregulated in propolis treated GBM cells compared to the control group, significantly (p<0.05). In the study, the potential roles of two new miRNAs, whose regulations in glioma were not previously defined, were identified. One of these miR-30d-5p, a novel potential oncomiR in GBM was 2.46 folds downregulated in Aydin propolis treated GBM cells. The other one is miR-335-5p which is a potential tumor suppressor miR in GBM, was 5.66 folds upregulated in Aydin propolis treated GBM cells. FOXO pathway and its upstream and downstream regulators and critically neuronal developmental regulators NOTCH and WNT pathways were determined as the most deregulated pathways in Aydin propolis treated cells.

CONCLUSION

The determination of the anti-cancer effect of Aydın propolis on the miRNA expression of GBM, especially on cancer stem cells, may contribute to the elucidation of brain cancer genetics by supporting further analyses.

Mechanisms of temozolomide resistance in glioblastoma - a comprehensive review

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and has an exceedingly low median overall survival of only 15 months. Current standard-of-care for GBM consists of gross total surgical resection followed by radiation with concurrent and adjuvant chemotherapy. Temozolomide (TMZ) is the first-choice chemotherapeutic agent in GBM; however, the development of resistance to TMZ often becomes the limiting factor in effective treatment. While O6-methylguanine-DNA methyltransferase repair activity and uniquely resistant populations of glioma stem cells are the most well-known contributors to TMZ resistance, many other molecular mechanisms have come to light in recent years. Key emerging mechanisms include the involvement of other DNA repair systems, aberrant signaling pathways, autophagy, epigenetic modifications, microRNAs, and extracellular vesicle production. This review aims to provide a comprehensive overview of the clinically relevant molecular mechanisms and their extensive interconnections to better inform efforts to combat TMZ resistance.

The miR-142 Suppresses U-87 Glioblastoma Cell Growth by Targeting EGFR Oncogenic Signaling Pathway

Glioblastoma is the most lethal malignancy of the brain and is resistant to conventional cancer treatments. Gene-therapy approaches like using tumor suppressor miRNAs are promising in the treatment of glioblastoma. They control the expression of oncogenes and influence tumor features and behaviors. Therefore, in the present study, it was predicted that miR-142 regulates oncogenic epidermal growth factor receptor (EGFR) signaling pathway via TargetScan and miRWalk online tools. Its differential expression level was reduced in glioblastoma according to the previous microarray results, and its predicted target genes were upregulated, as shown by the Expression Atlas. The miR-142 was overexpressed in U-87 glioblastoma cells via lentiviral transduction, and the way it influences proliferation and migration of cells was investigated through MTT assay and wound healing assay. Apoptosis rate was also measured via the Annexin V assay, and cell-cycle analysis was done. Then, real-time polymerase chain reaction (real-time PCR) and western blotting were performed to assess fold changes in mRNA and protein levels of the miR-142 predicted targets. Direct target genes of miR-142 were confirmed through a dual-luciferase reporter assay. The miR-142 significantly suppressed cell proliferation and migration and induced apoptosis and cell-cycle arrest in U-87 glioblastoma cells. This was accompanied by a decrease in expression of SHC adaptor protein 4 (SHC4), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), v-akt murine thymoma viral oncogene homolog 1 (AKT1), Kirsten rat sarcoma viral oncogene homolog (KRAS), and mitogen-activated protein kinase 8 (MAPK8) oncogenes at mRNA and protein levels in glioblastoma cells. Also, AKT1 was demonstrated as a direct target of miR-142. Overall, miR-424 acts as tumor suppressor miRNA in glioblastoma cells.

Differential Network Analysis via Weighted Fused Conditional Gaussian Graphical Model

The development and prognosis of complex diseases usually involves changes in regulatory relationships among biomolecules. Understanding how the regulatory relationships change with genetic alterations can help to reveal the underlying biological mechanisms for complex diseases. Although several models have been proposed to estimate the differential network between two different states, they are not suitable to deal with situations where the molecules of interest are affected by other covariates. Nor can they make use of prior information that provides insights about the structures of biomolecular networks. In this study, we introduce a novel weighted fused conditional Gaussian graphical model to jointly estimate two state-specific biomolecular regulatory networks and their difference between two different states. Unlike previous differential network estimation methods, our model can take into account the related covariates and the prior network information when inferring differential networks. The effectiveness of our proposed model is first evaluated based on simulation studies. Experiment results demonstrate that our model outperforms other state-of-the-art differential networks estimation models in all cases. We then apply our model to identify the differential gene network between two subtypes of glioblastoma based on gene expression and miRNA expression data. Our model is able to discover known mechanisms of glioblastoma and provide interesting predictions.

MiR-27b-3p promotes migration and invasion in colorectal cancer cells by targeting HOXA10

Purpose: Dysregulation of microRNAs (miRNAs) contributes to tumor progression via the regulation of the expression of specific oncogenes and tumor suppressor genes. One such example, miR-27b-3p, has reportedly been involved in tumor progression in many types of cancer. The aim of the present study was to delve into the role and the underlying mechanism of miR-27b-3p in colorectal cancer (CRC) cells. Methods: In the present study, we detected the expression level of miR-27b-3p by RT-PCR. The effect of miR-27b-3p overexpression on cell proliferation in CRC cells was evaluated by cell counting and Edu assays. Transwell migration and invasion assays were used to examine the effects of cell migration and invasion. Bioinformatics, luciferase reporter assay and western blot assay were performed to identify the target of miR-27b-3p. Results: Here, we have demonstrated that although miR-27b-3p can affect cell morphology, it has no observable effect on the proliferation of CRC cells. However, it significantly promotes the migration and invasion of CRC cells. We discovered that HOXA10 was a newly identified target of miR-27b-3p in CRC cells, as confirmed by bioinformatics, western blots and dual luciferase reporter assay. Furthermore, the overexpression of miR-27b-3p or the suppression of HOXA10 can activate the integrin β1 signaling pathway. In conclusion, our results reveal a new function of miR-27b-3p that demonstrates its ability to promote CRC cell migration and invasion by targeting the HOXA10/integrin β1 cell signal axis. Conclusion: This may provide a mechanism to explain why miR-27b-3p promotes CRC cell migration and invasion.

The Role of miRNA for the Treatment of MGMT Unmethylated Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common high-grade intracranial tumor in adults. It is characterized by uncontrolled proliferation, diffuse infiltration due to high invasive and migratory capacities, as well as intense resistance to chemo- and radiotherapy. With a five-year survival of less than 3% and an average survival rate of 12 months after diagnosis, GBM has become a focus of current research to urgently develop new therapeutic approaches in order to prolong survival of GBM patients. The methylation status of the promoter region of the O⁶-methylguanine–DNA methyltransferase (MGMT) is nowadays routinely analyzed since a methylated promoter region is beneficial for an effective response to temozolomide-based chemotherapy. Furthermore, several miRNAs were identified regulating MGMT expression, apart from promoter methylation, by degrading MGMT mRNA before protein translation. These miRNAs could be a promising innovative treatment approach to enhance Temozolomide (TMZ) sensitivity in MGMT unmethylated patients and to increase progression-free survival as well as long-term survival. In this review, the relevant miRNAs are systematically reviewed.

miR-142-3p as a novel biomarker for predicting poor prognosis in renal cell carcinoma patients after surgery

BACKGROUND

miR-142-3p has proved to be involved in tumorigenesis and the development of renal cell carcinoma. The present study aimed to explore the prognostic value of miR-142-3p.

METHODS

Total RNA was extracted from renal cell carcinoma specimens and the expression level of miR-142-3p was measured. Pearson Chi-square test, Kaplan-Meier analysis, as well as univariate and multivariate regression analysis were performed to determine the correlation between miR-142-3p and the prognosis of renal cell carcinoma patients. Receiver operating characteristic curves were constructed to evaluate the predictive efficiency of miR-142-3p for the prognosis of renal cell carcinoma patients. Data from The Cancer Genome Atlas (TCGA) were utilized to validate our findings.

RESULTS

Our results demonstrated that upregulation of miR-142-3p was correlated with shorter overall survival (P=0.002) and was, in the meantime, an independent prognostic factor for renal cell carcinoma patients (P=0.002). The receiver operating characteristic curve combining miR-142-3p expression with tumor stage showed an area under the curve of 0.633 (95% confidence interval 0.563, 0.702). The result of TCGA data was consistent with our findings.

CONCLUSIONS

Our results suggest miR-142-3p expression is correlated with poor prognosis of renal cell carcinoma patients and may serve as a prognostic biomarker in the future.

miR-155-5p Promotes Dorsal Root Ganglion Neuron Axonal Growth in an Inhibitory Microenvironment via the cAMP/PKA Pathway

Sensory dysfunction post spinal cord injury causes patients great distress. Sciatic nerve conditioning injury (SNCI) has been shown to restore sensory function after spinal cord dorsal column injury (SDCL); however, the underlying mechanism of this recovery remains unclear. We performed a microarray assay to determine the associated miRNAs that might regulate the process of SNCI promoting SDCL repair. In total, 13 miRNAs were identified according to our inclusion criteria, and RT-qPCR was used to verify the microarray results. Among the 13 miRNAs, the miR-155-5p levels were decreased at 9 h, 3 d, 7 d, 14 d, 28 d, 2 m and 3 m timepoints in the SDCL group, while the SNCI group had a smaller decrease. Thus, miR-155-5p was chosen for further study after a literature review and an analysis with the TargetScan online tool. Specifically, miR-155-5p targets PKI-α, and the expression pattern of PKI-α was opposite that of miR-155-5p in both the SDCL and SNCI groups. Interestingly, miR-155-5p could promote dorsal root ganglion (DRG) neuron axon growth via the cAMP/PKA pathway and in a TNF-α, IL-1β or MAG inhibitory microenvironment in vitro. Furthermore, miR-155-5p could regulate the cAMP/PKA pathway and promote sensory conduction function recovery post dorsal column injury as detected by NF-200 immunohistochemistry, somatosensory-evoked potentials, BBB scale and tape removal test. Collectively, our results demonstrated that miR-155-5p participates in the molecular mechanism by which SNCI promotes the repair of SDCL and that upregulated miR-155-5p can repair SDCL by enhancing DRG neuron axon growth via the cAMP/PKA pathway. These findings suggest a novel treatment target for spinal cord injury.

FAM98A promotes cancer progression in endometrial carcinoma

To investigate the expression status of FAM98A and its potential involvement in endometrial carcinoma, the relative expression of FAM98A in clinical endometrial carcinoma tissues was analyzed by immunohistochemistry and real-time polymerase chain reaction. Endogenous FAM98A protein was determined by Western blotting. The overall survival was calculated by the Kaplan-Meier's analysis. Cell growth/viability/proliferation was evaluated by cell counting, 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay, and clonogenic assay, respectively. Cell apoptosis was determined by the Annexin V/7-AAD double-staining methods followed by flow cytometry analysis. The regulatory effect of miR-142-3p on FAM98A was interrogated by luciferase reporter assay. Aberrant overexpression of FAM98A was found in endometrial carcinoma both in vitro and in vivo. Furthermore, high level of FMA98A was associated with poor prognosis. FAM98A deficiency in Ishikawa and RL95-2 cells significantly inhibited cell growth, cell viability, and cell proliferation. In addition, FAM98A-knockdown stimulated remarkable cell apoptosis, which might be mediated by down-regulation of BCL2 and up-regulation of BAX. Mechanistically, it was demonstrated that miR-142-3p directly targeted FAM98A, and modulated its expression. In conclusion, we unraveled the oncogenic properties of FAM98A in endometrial carcinoma and highlighted the miR-142-3p-FAM98A signaling in this disease.

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.