Tumor Suppressor WWOX and p53 Alterations and Drug Resistance in Glioblastomas

Pesticide-induced alterations in zebrafish (Danio rerio) behavior, histology, DNA damage and mRNA expression: An integrated approach

To assess the impact of glyphosate and 2,4-D herbicides, as well as the insecticide imidacloprid, both individually and in combination, the gills of adult zebrafish were used due to their intimate interaction with chemicals diluted in water. Bioassays were performed exposing the animals to the different pesticides and their mixture for 96 h. The behavior of the fish was analyzed, a histological examination of the gills was carried out, and the genotoxic effects were also analyzed by means of the comet assay (CA) and the change in the expression profiles of genes involved in the pathways of the oxidative stress and cellular apoptosis. The length traveled and the average speed of the control fish, compared to those exposed to the pesticides and mainly those exposed to the mixture, were significantly greater. All the groups exposed individually exhibited a decrease in thigmotaxis time, indicating a reduction in the behavior of protecting themselves from predators. Histological analysis revealed significant differences in the structures of the gill tissues. The quantification of the histological lesions showed mild lesions in the fish exposed to imidacloprid, moderate to severe lesions for glyphosate, and severe lesions in the case of 2,4-D and the mixture of pesticides. The CA revealed the sensitivity of gill cells to DNA damage following exposure to glyphosate, 2,4-D, imidacloprid and the mixture. Finally, both genes involved in the oxidative stress pathway and those related to the cell apoptosis pathway were overexpressed, while the ogg1 gene, involved in DNA repair, was downregulated.

Molecular landscapes of glioblastoma cell lines revealed a group of patients that do not benefit from WWOX tumor suppressor expression

Introduction

Glioblastoma (GBM) is notorious for its clinical and molecular heterogeneity, contributing to therapeutic failure and a grim prognosis. WWOX is one of the tumor suppressor genes important in nervous tissue or related pathologies, which was scarcely investigated in GBM for reliable associations with prognosis or disease progression despite known alterations. Recently, we observed a phenotypic heterogeneity between GBM cell lines (U87MG, T98G, U251MG, DBTRG-05MG), among which the anti-GBM activity of WWOX was generally corresponding, but colony growth and formation were inconsistent in DBTRG-05MG. This prompted us to investigate the molecular landscapes of these cell lines, intending to translate them into the clinical context.

Methods

U87MG/T98G/U251MG/DBTRG-05MG were subjected to high-throughput sequencing, and obtained data were explored via weighted gene co-expression network analysis, differential expression analysis, functional annotation, and network building. Following the identification of the most relevant DBTRG-distinguishing driver genes, data from GBM patients were employed for, e.g., differential expression analysis, survival analysis, and principal component analysis.

Results

Although most driver genes were unique for each cell line, some were inversely regulated in DBTRG-05MG. Alongside driver genes, the differentially-expressed genes were used to build a WWOX-related network depicting protein-protein interactions in U87MG/T98G/U251MG/DBTRG-05MG. This network revealed processes distinctly regulated in DBTRG-05MG, e.g., microglia proliferation or neurofibrillary tangle assembly. POLE4 and HSF2BP were selected as DBTRG-discriminating driver genes based on the gene significance, module membership, and fold-change. Alongside WWOX, POLE4 and HSF2BP expression was used to stratify patients into cell lines-resembling groups that differed in, e.g., prognosis and treatment response. Some differences from a WWOX-related network were certified in patients, revealing genes that clarify clinical outcomes. Presumably, WWOX overexpression in DBTRG-05MG resulted in expression profile change resembling that of patients with inferior prognosis and drug response. Among these patients, WWOX may be inaccessible for its partners and does not manifest its anti-cancer activity, which was proposed in the literature but not regarding glioblastoma or concerning POLE4 and HSF2BP.

Conclusion

Cell lines data enabled the identification of patients among which, despite high expression of WWOX tumor suppressor, no advantageous outcomes were noted due to the cancer-promoting profile ensured by other genes.

2,4-Dichlorophenoxyacetic acid (2,4-D) affects DNA integrity and retina structure in zebrafish larvae

Monitoring the potential risk of herbicides in non-target organisms is a crucial issue for environmental safety. 2,4-D is an herbicide of high environmental relevance that has been shown to exert toxic effects to soil and aquatic biota. In the present study, we investigated the possible genotoxic and retinal development effects of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide in early life stages zebrafish (Danio rerio). Genotoxicity was evaluated by measuring DNA damage using the comet assay and also by the mRNA expression of genes implicated in apoptosis and/or DNA repair. Retinal development toxicity was evaluated with histological approach. The results obtained revealed that 2,4-D alters DNA integrity of zebrafish larvae. Moreover, transcriptomic data showed a significant induction of p-53 and casp-3 genes and a significant decrease of lig-4 in larvae exposed to the highest tested concentration of 2,4-D (0.8 mg/L). This suggested that p-53 gene regulates the process of DNA repair and apoptosis with increased levels of 2,4-D. The histopathological analysis revealed that early exposure to 2,4-D damaged the structure of larvae retina. Overall, this study is the first to report the DNA damage, casp-3, lig-4 and p-53 regulation, as well as the ocular developmental toxicity in zebrafish larvae at environmentally relevant concentrations of 2,4-D herbicide.

WWOX-Related Neurodevelopmental Disorders: Models and Future Perspectives

The WW domain-containing oxidoreductase (WWOX) gene was originally discovered as a putative tumor suppressor spanning the common fragile site FRA16D, but as time has progressed the extent of its pleiotropic function has become apparent. At present, WWOX is a major source of interest in the context of neurological disorders, and more specifically developmental and epileptic encephalopathies (DEEs). This review article aims to introduce the many model systems used through the years to study its function and roles in neuropathies. Similarities and fundamental differences between rodent and human models are discussed. Finally, future perspectives and promising research avenues are suggested.

The Role of p53 Expression in Patients with RAS/BRAF Wild-Type Metastatic Colorectal Cancer Receiving Irinotecan and Cetuximab as Later Line Treatment

Background

Preclinical and clinical data indicate that p53 expression might modulate the activity of the epidermal growth factor receptor (EGFR), influencing response/resistance to anti-EGFR monoclonal antibodies. However, the association between p53 status and clinical outcome has not been clarified yet.

Objective

In our study, we evaluated the role of p53 expression in patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC) receiving irinotecan/cetuximab in an exploratory and a validation cohort.

Patients and Methods

p53 expression was analysed in patients with RAS/BRAF wild-type mCRC receiving second-line or third-line irinotecan/cetuximab. Survival distribution was assessed by the Kaplan–Meier method, while the log-rank test was used for survival comparison.

Results

Among 120 patients with RAS/BRAF wild-type mCRC included in our analysis, 52 (59%) and 19 (59%) patients showed p53 overexpression in the exploratory and validation cohort, respectively. In the exploratory cohort, low p53 expression was correlated with better median progression-free survival (hazard ratio 0.39; p < 0.0001), median overall survival (hazard ratio: 0.23; p < 0.0001) and response rate (p < 0.0001). These results were confirmed by data of the validation cohort where we observed better median progression-free survival (hazard ratio: 0.48; p = 0.0399), median overall survival (hazard ratio: 0.26; p = 0.0027) and response rate (p =0.0007) in patients with p53 normal expression mCRC.

Conclusions

In our study, p53 overexpression was associated with anti-EGFR treatment resistance in patients with RAS/BRAF WT mCRC, as confirmed in a validation cohort. Larger studies are needed to validate the role of p53 and investigate EGFR cross-talk in these patients.

Protective role of anticancer drugs in neurodegenerative disorders: A drug repurposing approach

The disease heterogeneity and little therapeutic progress in neurodegenerative diseases justify the need for novel and effective drug discovery approaches. Drug repurposing is an emerging approach that reinvigorates the classical drug discovery method by divulging new therapeutic uses of existing drugs. The common biological background and inverse tuning between cancer and neurodegeneration give weight to the conceptualization of repurposing of anticancer drugs as novel therapeutics. Many studies are available in the literature, which highlights the success story of anticancer drugs as repurposed therapeutics. Among them, kinase inhibitors, developed for various oncology indications evinced notable neuroprotective effects in neurodegenerative diseases. In this review, we shed light on the salient role of multiple protein kinases in neurodegenerative disorders. We also proposed a feasible explanation of the action of kinase inhibitors in neurodegenerative disorders with more attention towards neurodegenerative disorders. The problem of neurotoxicity associated with some anticancer drugs is also highlighted. Our review encourages further research to better encode the hidden potential of anticancer drugs with the aim of developing prospective repurposed drugs with no toxicity for neurodegenerative disorders.

A Potential Mechanism of Temozolomide Resistance in Glioma-Ferroptosis

Temozolomide (TMZ) is the first-line chemotherapy drug that has been used to treat glioma for over a decade, but the benefits are limited by half of the treated patients who acquired resistance. Studies have shown that glioma TMZ resistance is a complex process with multiple factors, which has not been fully elucidated. Ferroptosis, which is a new type of cell death discovered in recent years, has been reported to play an important role in tumor drug resistance. The present study reviews the relationship between ferroptosis and glioma TMZ resistance, and highlights the role of ferroptosis in glioma TMZ resistance. Finally, the investigators discussed the future orientation for ferroptosis in glioma TMZ resistance, in order to promote the clinical use of ferroptosis induction in glioma treatment.

The WWOX gene in brain development and pathology

Shortly after its discovery in 2000, WWOX was hailed as a tumor suppressor gene. In subsequent years of research, this function was confirmed indisputably. Majority of tumors show high rate of loss of heterozygosity and decreased expression of WWOX. Nevertheless, over the years, the range of its known functions, at the cellular, organ and system levels, has expanded to include metabolism and endocrine system control and CNS differentiation and functioning. Despite of its function as a tumor suppressor gene, WWOX genetic alternations were found in a number of metabolic and neural diseases. A lack of WWOX protein as a consequence of germline mutations results in brain development disturbances and malfunctions.

Implementing Patient-Derived Xenografts to Assess the Effectiveness of Cyclin-Dependent Kinase Inhibitors in Glioblastoma

Glioblastoma (GBM) is the most common primary brain tumor with no available cure. As previously described, seliciclib, a first-generation cyclin-dependent kinase (CDK) inhibitor, down-regulates the anti-apoptotic protein, Mcl-1, in GBM, thereby sensitizing GBM cells to the apoptosis-inducing effects of the death receptor ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we have assessed the efficacy of seliciclib when delivered in combination with the antibody against human death receptor 5, drozitumab, in clinically relevant patient-derived xenograft (PDX) models of GBM. A reduction in viability and significant levels of apoptosis were observed in vitro in human GBM neurospheres following treatment with seliciclib plus drozitumab. While the co-treatment strategy induced a similar effect in PDX models, the dosing regimen required to observe seliciclib-targeted responses in the brain, resulted in lethal toxicity in 45% of animals. Additional studies showed that the second-generation CDK inhibitor, CYC065, with improved potency in comparison to seliciclib, induced a significant decrease in the size of human GBM neurospheres in vitro and was well tolerated in vivo, upon administration at clinically relevant doses. This study highlights the continued need for robust pre-clinical assessment of promising treatment approaches using clinically relevant models.

Circular RNA CircMTO1 Inhibits Proliferation of Glioblastoma Cells via miR-92/WWOX Signaling Pathway

Background

Circular RNA circMTO1 has been reported to inhibit the progression of many types of cancers. However, the role of circMTO1 in the progression of glioblastoma remains unclear. The purpose of our study was to explore the potential involvement of circMTO1 in glioblastoma.

Material/Methods

The expression of circMTO1 in human glioblastoma tissues was determined via quantitative real-time polymerase chain reaction (qRT-PCR). The effect of circMTO1 on proliferation of human glioblastoma cell line U251 was assessed through the Cell Counting Kit-8 (CCK-8) and colony formation assay. The regulatory interaction between circMTO1 and miR-92 was explored by bioinformatics prediction and luciferase reporter assay.

Results

We showed that circMTO1 was markedly downregulated in glioblastoma tissues compared with adjacent normal tissues. Lower circMTO1 level was significantly associated with shorter overall survival among patients with glioblastoma. In addition, circMTO1 inhibited proliferation of cell U251 cells. Mechanistically, circMTO1 upregulates the expression of WWOX in U251 cells, and WWOX mediates circMTO1-induced inhibition of proliferation of U251 cells. In addition, miR-92 downregulates the expression of WWOX by the targeting its mRNA 3′ UTR. More importantly, circMTO1 directly interact with miR-92, and subsequently serves as a miRNA sponge to upregulate WWOX expression.

Conclusions

Our results demonstrate that circMTO1 inhibits the proliferation of glioblastoma cells via the miR-92/WWOX signaling pathway.

Decoding the link between WWOX and p53 in aggressive breast cancer

Basal-like breast cancer (BLBC) and triple-negative breast cancer (TNBC) are aggressive forms of human breast cancer with poor prognosis and limited treatment response. Molecular understanding of BLBC and TNBC biology is instrumental to improve detection and management of these deadly diseases. Tumor suppressors WW domain-containing oxidoreductase (WWOX) and TP53 are altered in BLBC and in TNBC. Nevertheless, the functional interplay between WWOX and p53 is poorly understood. In a recent study by Abdeen and colleagues, it has been demonstrated that WWOX loss drives BLBC formation via deregulating p53 functions. In this review, we highlight important signaling pathways regulated by WWOX and p53 that are related to estrogen receptor signaling, epithelial-to-mesenchymal transition, and genomic instability and how they impact BLBC and TNBC development.

The downregulation of WWOX induces epithelial-mesenchymal transition and enhances stemness and chemoresistance in breast cancer

IMPACT STATEMENT

Overcoming resistance to chemotherapy is one of the fundamental issues of clinical treatment and CSCs are responsible for the poor therapeutic effects of chemotherapy. WW domain-containing oxidoreductase (WWOX), an important tumor suppressor, regulates cancer cells' response to chemotherapy. The major finding of our study is the novel role of WWOX in the chemoresistance of breast cancer through the regulation of cell stemness and EMT. The plasticity may play a crucial role in tumor metastasis, treatment resistance and tumor recurrence. Our findings may shed new light on the alterations of BCSCs and pave the way for the discovery of novel and more effective therapies to treat breast cancer by targeting WWOX.

Predicting the cell death responsiveness and sensitization of glioma cells to TRAIL and temozolomide

Genotoxic chemotherapy with temozolomide (TMZ) is a mainstay of treatment for glioblastoma (GBM); however, at best, TMZ provides only modest survival benefit to a subset of patients. Recent insight into the heterogeneous nature of GBM suggests a more personalized approach to treatment may be necessary to overcome cancer drug resistance and improve patient care. These include novel therapies that can be used both alone and with TMZ to selectively reactivate apoptosis within malignant cells. For this approach to work, reliable molecular signatures that can accurately predict treatment responsiveness need to be identified first. Here, we describe the first proof-of-principle study that merges quantitative protein-based analysis of apoptosis signaling networks with data- and knowledge-driven mathematical systems modeling to predict treatment responsiveness of GBM cell lines to various apoptosis-inducing stimuli. These include monotherapies with TMZ and TRAIL, which activate the intrinsic and extrinsic apoptosis pathways, respectively, as well as combination therapies of TMZ+TRAIL. We also successfully employed this approach to predict whether individual GBM cell lines could be sensitized to TMZ or TRAIL via the selective targeting of Bcl-2/Bcl-xL proteins with ABT-737. Our findings suggest that systems biology-based approaches could assist in personalizing treatment decisions in GBM to optimize cell death induction.

The role of p53 in cancer drug resistance and targeted chemotherapy

Cancer has long been a grievous disease complicated by innumerable players aggravating its cure. Many clinical studies demonstrated the prognostic relevance of the tumor suppressor protein p53 for many human tumor types. Overexpression of mutated p53 with reduced or abolished function is often connected to resistance to standard medications, including cisplatin, alkylating agents (temozolomide), anthracyclines, (doxorubicin), antimetabolites (gemcitabine), antiestrogenes (tamoxifen) and EGFR-inhibitors (cetuximab). Such mutations in the TP53 gene are often accompanied by changes in the conformation of the p53 protein. Small molecules that restore the wild-type conformation of p53 and, consequently, rebuild its proper function have been identified. These promising agents include PRIMA-1, MIRA-1, and several derivatives of the thiosemicarbazone family. In addition to mutations in p53 itself, p53 activity may be also be impaired due to alterations in p53s regulating proteins such as MDM2. MDM2 functions as primary cellular p53 inhibitor and deregulation of the MDM2/p53-balance has serious consequences. MDM2 alterations often result in its overexpression and therefore promote inhibition of p53 activity. To deal with this problem, a judicious approach is to employ MDM2 inhibitors. Several promising MDM2 inhibitors have been described such as nutlins, benzodiazepinediones or spiro-oxindoles as well as novel compound classes such as xanthone derivatives and trisubstituted aminothiophenes. Furthermore, even naturally derived inhibitor compounds such as a-mangostin, gambogic acid and siladenoserinols have been discovered. In this review, we discuss in detail such small molecules that play a pertinent role in affecting the p53-MDM2 signaling axis and analyze their potential as cancer chemotherapeutics.

BACH1 Promotes Temozolomide Resistance in Glioblastoma through Antagonizing the Function of p53

The acquisition of drug resistance is a persistent clinical problem limiting the successful treatment of glioblastoma (GBM). However, the molecular mechanisms by which initially chemoresponsive tumors develop therapeutic resistance remain poorly understood. In this study, we report that BACH1, a heme-binding protein that participates in transcriptional repression or activation, was significantly upregulated in glioblastoma tissues. Overexpression of BACH1 in GBM cells conferred resistance to temozolomide, whereas its inhibition markedly sensitized resistant cells to temozolomide in vitro and in vivo. Further investigation revealed that BACH1 activation significantly enhanced the expression of MGMT, and depletion of p53 disrupted the effects of BACH1 on MGMT and temozolomide resistance. P53 sequesters SP1 to prevent its binding to the MGMT promoter region and thus inhibits MGMT expression. Moreover, BACH1 overexpression impaired the association between p53 and SP1 via competitive binding p53, and antagonized the impact of p53 on MGMT expression. Finally, we found that BACH1 low expression correlated with better prognosis in GBM patients undergoing temozolomide therapy, especially in patients with wild-type TP53. Collectively, our findings identify a potential mechanism by which wild-type TP53 GBM cells develop resistance to temozolomide and suggest that targeting this pathway may be beneficial for overcoming resistance.

Mechanistic Nanotherapeutic Approach Based on siRNA-Mediated DJ-1 Protein Suppression for Platinum-Resistant Ovarian Cancer

We report an efficient therapeutic modality for platinum resistant ovarian cancer based on siRNA-mediated suppression of a multifunctional DJ-1 protein that is responsible for the proliferation, growth, invasion, oxidative stress, and overall survival of various cancers. The developed therapeutic strategy can work alone or in concert with a low dose of the first line chemotherapeutic agent cisplatin, to elicit a maximal therapeutic response. To achieve an efficient DJ-1 knockdown, we constructed the polypropylenimine dendrimer-based nanoplatform targeted to LHRH receptors overexpressed on ovarian cancer cells. The quantitative PCR and Western immunoblotting analysis revealed that the delivered DJ-1 siRNA downregulated the expression of targeted mRNA and corresponding protein by more than 80% in various ovarian cancer cells. It was further demonstrated that siRNA-mediated DJ-1 suppression dramatically impaired proliferation, viability, and migration of the employed ovarian cancer cells. Finally, the combinatorial approach led to the most pronounced therapeutic response in all the studied cell lines, outperforming both siRNA-mediated DJ-1 knockdown and cisplatin treatment alone. It is noteworthy that the platinum-resistant cancer cells (A2780/CDDP) with the highest basal level of DJ-1 protein are most susceptible to the developed therapy and this susceptibility declines with decreasing basal levels of DJ-1. Finally, we interrogate the molecular underpinnings of the DJ-1 knockdown effects in the treatment of the ovarian cancer cells. By using various experimental techniques, it was revealed that DJ-1 depletion (1) decreases the activity of the Akt pathway, thereby reducing cellular proliferation and migration and increasing the antiproliferative effect of cisplatin on ovarian cancer cells; (2) enhances the activity of p53 tumor suppressor protein therefore restoring cell cycle arrest functionality and upregulating the Bax-caspase pathway, triggering cell death; and (3) weakens the cellular defense mechanisms against inherited oxidative stress thereby increasing toxic intracellular radicals and amplifying the reactive oxygen species created by the administration of cisplatin.

WW domain-containing oxidoreductase in neuronal injury and neurological diseases

The human and mouse WWOX/Wwox gene encodes a candidate tumor suppressor WW domain-containing oxidoreductase protein. This gene is located on a common fragile site FRA16D. WWOX participates in a variety of cellular events and acts as a transducer in the many signal pathways, including TNF, chemotherapeutic drugs, UV irradiation, Wnt, TGF-β, C1q, Hyal-2, sex steroid hormones, and others. While transiently overexpressed WWOX restricts relocation of transcription factors to the nucleus for suppressing cancer survival, physiological relevance of this regard in vivo has not been confirmed. Unlike many tumor suppressor genes, mutation of WWOX is rare, raising a question whether WWOX is a driver for cancer initiation. WWOX/Wwox was initially shown to play a crucial role in neural development and in the pathogenesis of Alzheimer's disease and neuronal injury. Later on, WWOX/Wwox was shown to participate in the development of epilepsy, mental retardation, and brain developmental defects in mice, rats and humans. Up to date, most of the research and review articles have focused on the involvement of WWOX in cancer. Here, we review the role of WWOX in neural injury and neurological diseases, and provide perspectives for the WWOX-regulated neurodegeneration.

Introduction to a thematic issue for WWOX

Since its discovery in 2000, WW domain-containing oxidoreductase (WWOX, FOR or WOX1) has been considered as a tumor suppressor protein. Global research focus has been aimed mainly toward this direction. In this thematic issue, updated information has been collected regarding the structure, function and signaling of WWOX, along with its critical role as a tumor suppressor and participation in metabolism, neurodegeneration, ataxia, epilepsy, neural disorders, neuronal damages, and interactions with oncogenic viruses. WWOX is not a driver of cancer initiation. Chromosomal alterations in the WWOX gene enhance cancer progression. Importantly, a homozygous nonsense mutation of WWOX gene in humans leads to neural pathologies and early death, rather than spontaneous cancer development. These findings suggest new physiological functions of WWOX in metabolism and neural diseases, and these areas require further investigation.

Alteration of WWOX in human cancer: a clinical view

WWOX gene is located in FRA16D, the highly affected chromosomal fragile site. Its tumor suppressor activity has been proposed on a basis of numerous genomic alterations reported in chromosome 16q23.3-24.1 locus. WWOX is affected in many cancers, showing as high as 80% loss of heterozygosity in breast tumors. Unlike most tumor suppressors impairing of both alleles of WWOX is very rare. Despite cellular and animal models information on a WWOX role in cancer tissue is limited and sometimes confusing. This review summarizes information on WWOX in human tumors.

Role of WWOX and NF-κB in lung cancer progression

It is generally agreed that the pro-inflammatory, pro-survival transcription factor NF-κB is a tumor promoter. Tumor necrosis factor alpha (TNF-α or TNF) mediates NF-κB activation. Tumor suppressor WWOX (FOR or WOX1) is a downstream effector of the TNF signaling. Thus, activation of both WWOX (FOR or WOX1) and NF-κB may occur during TNF signaling and/or under stress conditions. Indeed, the first WW domain of WWOX induces the activation of NF-κB-responsive promoter without TNF participation. It appears that WWOX counteracts with NF-κB in regulating cell survival and death. For example, WWOX becomes activated with Tyr33 phosphorylation and relocates together with NF-κB and many transcription factors to the nucleus to cause neuronal death in sciatic nerve-transected rats. While WWOX is frequently lost in lung cancer and many other cancers, NF-κB activation-induced cancer promotion probably requires WWOX-independent signaling networks to induce expression of pro-survival factors. The antagonistic role of WWOX and NF-κB in the regulation of lung cancer progression is discussed.

Emerging biomarkers in glioblastoma

Glioblastoma, the most common primary brain tumor, has few available therapies providing significant improvement in survival. Molecular signatures associated with tumor aggressiveness as well as with disease progression and their relation to differences in signaling pathways implicated in gliomagenesis have recently been described. A number of biomarkers which have potential in diagnosis, prognosis and prediction of response to therapy have been identified and along with imaging modalities could contribute to the clinical management of GBM. Molecular biomarkers including O(6)-methlyguanine-DNA-methyltransferase (MGMT) promoter and deoxyribonucleic acid (DNA) methylation, loss of heterozygosity (LOH) of chromosomes 1p and 19q, loss of heterozygosity 10q, isocitrate dehydrogenase (IDH) mutations, epidermal growth factor receptor (EGFR), epidermal growth factor, latrophilin, and 7 transmembrane domain-containing protein 1 on chromosome 1 (ELTD1), vascular endothelial growth factor (VEGF), tumor suppressor protein p53, phosphatase and tensin homolog (PTEN), p16INK4a gene, cytochrome c oxidase (CcO), phospholipid metabolites, telomerase messenger expression (hTERT messenger ribonucleic acid [mRNA]), microRNAs (miRNAs), cancer stem cell markers and imaging modalities as potential biomarkers are discussed. Inclusion of emerging biomarkers in prospective clinical trials is warranted in an effort for more effective personalized therapy in the future.

Emerging biomarkers in glioblastoma

Glioblastoma, the most common primary brain tumor, has few available therapies providing significant improvement in survival. Molecular signatures associated with tumor aggressiveness as well as with disease progression and their relation to differences in signaling pathways implicated in gliomagenesis have recently been described. A number of biomarkers which have potential in diagnosis, prognosis and prediction of response to therapy have been identified and along with imaging modalities could contribute to the clinical management of GBM. Molecular biomarkers including O(6)-methlyguanine-DNA-methyltransferase (MGMT) promoter and deoxyribonucleic acid (DNA) methylation, loss of heterozygosity (LOH) of chromosomes 1p and 19q, loss of heterozygosity 10q, isocitrate dehydrogenase (IDH) mutations, epidermal growth factor receptor (EGFR), epidermal growth factor, latrophilin, and 7 transmembrane domain-containing protein 1 on chromosome 1 (ELTD1), vascular endothelial growth factor (VEGF), tumor suppressor protein p53, phosphatase and tensin homolog (PTEN), p16INK4a gene, cytochrome c oxidase (CcO), phospholipid metabolites, telomerase messenger expression (hTERT messenger ribonucleic acid [mRNA]), microRNAs (miRNAs), cancer stem cell markers and imaging modalities as potential biomarkers are discussed. Inclusion of emerging biomarkers in prospective clinical trials is warranted in an effort for more effective personalized therapy in the future.