Effect of combination treatment of rapamycin and isoflavones on mTOR pathway in human glioblastoma (U87) cells

A novel approach to glioblastoma multiforme treatment using modulation of key pathways by naturally occurring small molecules

Glioblastoma multiforme (GBM), the fatal primary brain malignancy in adults, represents significant health challenges, and its eradication has been the ultimate goal of numerous medical investigations. GBM therapy encompasses various interventions, e.g., chemotherapy by synthetic cytotoxic agents like temozolomide (TMZ), radiotherapy, and, more recently, immunotherapy. A notable focus has been on incorporating naturally occurring substances in treating malignancies. Polyphenols and terpenoids, widely present in fruits and vegetables, constitute primary categories of agents employed for this purpose. They pose direct and indirect impacts on tumor growth and chemoresistance, mainly through impacting the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling, crucial in cellular processes, metabolism, and programmed death. This paper thoroughly discusses the biologic effects and practical application of polyphenols and terpenoids on GBM through the PI3K/Akt/mTOR signaling in vitro and in vivo.

Harnessing Therapeutic Potentials of Biochanin A in Neurological Disorders: Pharmacokinetic and Pharmacodynamic Overview

Biochanin A, an isoflavone flavonoid with estrogenic activity, is naturally found in red clover and other legumes. It possesses a wide range of pharmacological properties, including antioxidant, anti-inflammatory, anti-apoptotic, neuroprotective, and anticancer effects. In recent years, a growing body of pre-clinical research has focused on exploring the therapeutic potential of biochanin A in various neurological disorders, such as Alzheimer's and Parkinson's disease, multiple sclerosis, epilepsy, ischemic brain injury, gliomas, and neurotoxicity. This comprehensive review aims to shed light on the underlying molecular mechanisms that contribute to the neuroprotective role of biochanin A based on previous pre-clinical studies. Furthermore, it provides a detailed overview of the protective effects of biochanin A in diverse neurological disorders. The review also addresses the limitations associated with biochanin A administration and discusses different approaches employed to overcome these challenges. Finally, it highlights the future opportunities for translating biochanin A from pre-clinical research to clinical studies while also considering its commercial viability as a dietary supplement or a potential treatment for various diseases.

Bioactive compounds from nature: Antioxidants targeting cellular transformation in response to epigenetic perturbations induced by oxidative stress

Oxidative stress results from a persistent imbalance in oxidation levels that promotes oxidants, playing a crucial role in the early and sustained phases of DNA damage and genomic and epigenetic instability, both of which are intricately linked to the development of tumors. The molecular pathways contributing to carcinogenesis in this context, particularly those related to double-strand and single-strand breaks in DNA, serve as indicators of DNA damage due to oxidation in cancer cases, as well as factors contributing to epigenetic instability through ectopic expressions. Oxidative stress has been considered a therapeutic target for many years, and an increasing number of studies have highlighted the promising effectiveness of natural products in cancer treatment. In this regard, we present significant research on the therapeutic targeting of oxidative stress using natural molecules and underscore the essential role of oxidative stress in cancer. The consequences of stress, especially epigenetic instability, also offer significant therapeutic prospects. In this context, the use of natural epi-drugs capable of modulating and reorganizing the epigenetic network is beginning to emerge remarkably. In this review, we emphasize the close connections between oxidative stress, epigenetic instability, and tumor transformation, while highlighting the role of natural substances as antioxidants and epi-drugs in the anti-tumoral context.

Anticancer Mechanism of Flavonoids on High-Grade Adult-Type Diffuse Gliomas

High-grade adult-type diffuse gliomas are the most common and deadliest malignant adult tumors of the central nervous system. Despite the advancements in the multimodality treatment of high-grade adult-type diffuse gliomas, the five-year survival rates still remain poor. The biggest challenge in treating high-grade adult-type diffuse gliomas is the intra-tumor heterogeneity feature of the glioma tumors. Introducing dietary flavonoids to the current high-grade adult-type diffuse glioma treatment strategies is crucial to overcome this challenge, as flavonoids can target several molecular targets. This review discusses the anticancer mechanism of flavonoids (quercetin, rutin, chrysin, apigenin, naringenin, silibinin, EGCG, genistein, biochanin A and C3G) through targeting molecules associated with high-grade adult-type diffuse glioma cell proliferation, apoptosis, oxidative stress, cell cycle arrest, migration, invasion, autophagy and DNA repair. In addition, the common molecules targeted by the flavonoids such as Bax, Bcl-2, MMP-2, MMP-9, caspase-8, caspase-3, p53, p38, Erk, JNK, p38, beclin-1 and LC3B were also discussed. Moreover, the clinical relevance of flavonoid molecular targets in high-grade adult-type diffuse gliomas is discussed with comparison to small molecules inhibitors: ralimetinib, AMG232, marimastat, hydroxychloroquine and chloroquine. Despite the positive pre-clinical results, further investigations in clinical studies are warranted to substantiate the efficacy and safety of the use of flavonoids on high-grade adult-type diffuse glioma patients.

Recent updates on the role of phytochemicals in the treatment of glioblastoma multiforme

ABSTRACTS

Glioblastoma multiforme (GBM) is a malignant type of glioma. This malignant brain tumor is a devastating disease and is often fatal. The spectrum of illness and poor prognosis associated with brain tumors extract a terrible toll on patients and their families. The inoperability of these tumors and resistance to radiation and chemotherapy contribute to the fatal outcome of this disease. Thus, scientists are hunting for the new drug candidate and safer chemoprevention, especially the phytochemicals that possess potent anti-tumor properties. We have summarized the cellular and biochemical impacts of different phytochemicals that can successfully encounter GBM via induction of apoptosis and active interference in different cell and molecular pathways associated with GBM in brain tumors. The in silico predictive model determining the blood-brain barrier permeability of the compound and their potential druggability are discussed in the review.

The natural isoflavone Biochanin-A synergizes 5-fluorouracil anticancer activity in vitro and in vivo in Ehrlich solid-phase carcinoma model

Isoflavones are considered one of the most extensively studied plant-derived phytoestrogenic compounds. Of these, Biochanin A (Bio-A), a natural isoflavone abundant in cabbage, alfalfa, and red clover, has drawn a lot of attention. As reported in multiple studies, Bio-A possesses a promising anticancer activity against estrogen receptor-positive (ER+)  breast cancer. The current study investigated the working hypothesis that Bio-A could synergistically enhance the potency of 5-fluorouracil (5-FU) in ER+ breast cancer. The hypothesis was tested both in vitro on hormone receptor-positive (MCF-7) and triple-negative breast cancer cells (MDA-MB231). Additionally, in vivo studies were performed in the Ehrlich solid-phase carcinoma mouse model. The in vitro cytotoxicity studies revealed that Bio-A synergistically increased the potency of 5-FU in both MCF-7 and MDA-MB231 cell lines. The synergistic effect of 5-FU/Bio-A combination was verified in vivo. The combination therapy (where 5-FU was used at one fourth its full dose) led to a significant 75% reduction in tumor volume after two treatment cycles. This was in addition to producing a significant 2.1-fold increase in tumor necrosis area% compared to mock-treated control. In conclusion, the current study presents the first preclinical evidence for the potential merit of 5-FU/Bio-A combination for the treatment of ER+ breast cancer. The synergistic antitumor effect of Bio-A/ 5-FU combination can be, at least partly, attributed to Bio-A-mediated suppression of ER-α/Akt axis and the augmentation of 5-FU-mediated proapoptotic effects. © 2022 John Wiley & Sons, Ltd.

IDH Mutations in Glioma: Double-Edged Sword in Clinical Applications?

Discovery of point mutations in the genes encoding isocitrate dehydrogenases (IDH) in gliomas about a decade ago has challenged our view of the role of metabolism in tumor progression and provided a new stratification strategy for malignant gliomas. IDH enzymes catalyze the conversion of isocitrate to alpha-ketoglutarate (α-KG), an intermediate in the citric acid cycle. Specific mutations in the genes encoding IDHs cause neomorphic enzymatic activity that produces D-2-hydroxyglutarate (2-HG) and result in the inhibition of α-KG-dependent enzymes such as histone and DNA demethylases. Thus, chromatin structure and gene expression profiles in IDH-mutant gliomas appear to be different from those in IDH-wildtype gliomas. IDH mutations are highly common in lower grade gliomas (LGG) and secondary glioblastomas, and they are among the earliest genetic events driving tumorigenesis. Therefore, inhibition of mutant IDH enzymes in LGGs is widely accepted as an attractive therapeutic strategy. On the other hand, the metabolic consequences derived from IDH mutations lead to selective vulnerabilities within tumor cells, making them more sensitive to several therapeutic interventions. Therefore, instead of shutting down mutant IDH enzymes, exploiting the selective vulnerabilities caused by them might be another attractive and promising strategy. Here, we review therapeutic options and summarize current preclinical and clinical studies on IDH-mutant gliomas.

Current Perspective on the Natural Compounds and Drug Delivery Techniques in Glioblastoma Multiforme

Simple Summary

Glioblastoma multiforme (GBM) is one of the belligerent neoplasia that metastasize to other brain regions and invade nearby healthy tissues. However, the treatments available are associated with some limitations, such as high variations in solid tumors and deregulation of multiple cellular pathways. The heterogeneity of the GBM tumor and its aggressive infiltration into the nearby tissues makes it difficult to treat. Hence, the development of multimodality therapy that can be more effective, novel, with fewer side effects, improving the prognosis for GBM is highly desired. This review evaluated the use of natural phytoconstituents as an alternative for the development of a new therapeutic strategy. The key aspects of GBM and the potential of drug delivery techniques were also assessed, for tumor site delivery with limited side-effects. These efforts will help to provide better therapeutic options to combat GBM in future.

Abstract

Glioblastoma multiforme (GBM) is one of the debilitating brain tumors, being associated with extremely poor prognosis and short median patient survival. GBM is associated with complex pathogenesis with alterations in various cellular signaling events, that participate in cell proliferation and survival. The impairment in cellular redox pathways leads to tumorigenesis. The current standard pharmacological regimen available for glioblastomas, such as radiotherapy and surgical resection following treatment with chemotherapeutic drug temozolomide, remains fatal, due to drug resistance, metastasis and tumor recurrence. Thus, the demand for an effective therapeutic strategy for GBM remains elusive. Hopefully, novel products from natural compounds are suggested as possible solutions. They protect glial cells by reducing oxidative stress and neuroinflammation, inhibiting proliferation, inducing apoptosis, inhibiting pro-oncogene events and intensifying the potent anti-tumor therapies. Targeting aberrant cellular pathways in the amelioration of GBM could promote the development of new therapeutic options that improve patient quality of life and extend survival. Consequently, our review emphasizes several natural compounds in GBM treatment. We also assessed the potential of drug delivery techniques such as nanoparticles, Gliadel wafers and drug delivery using cellular carriers which could lead to a novel path for the obliteration of GBM.

Anti-neoplastic Potential of Flavonoids and Polysaccharide Phytochemicals in Glioblastoma

Clinically, gliomas are classified into four grades, with grade IV glioblastoma multiforme being the most malignant and deadly, which accounts for 50% of all gliomas. Characteristically, glioblastoma involves the aggressive proliferation of cells and invasion of normal brain tissue, outcomes as poor patient prognosis. With the current standard therapy of glioblastoma; surgical resection and radiotherapy followed by adjuvant chemotherapy with temozolomide, it remains fatal, because of the development of drug resistance, tumor recurrence, and metastasis. Therefore, the need for the effective therapeutic option for glioblastoma remains elusive. Previous studies have demonstrated the chemopreventive role of naturally occurring pharmacological agents through preventing or reversing the initiation phase of carcinogenesis or arresting the cancer progression phase. In this review, we discuss the role of natural phytochemicals in the amelioration of glioblastoma, with the aim to improve therapeutic outcomes, and minimize the adverse side effects to improve patient's prognosis and enhancing their quality of life.

Biochanin A: A novel bioactive multifunctional compound from nature

Natural products (NPs) will continue to serve humans as matchless source of novel drug leads and an inspiration for the synthesis of non-natural drugs. As our scientific understanding of 'nature' is rapidly expanding, it would be worthwhile to illuminate the pharmacological distinctions of NPs to the scientific community and the public. Flavonoids have long fascinated scientists with their remarkable structural diversity as well as biological functions. Consequently, this review aims to shed light on the sources and pharmacological significance of a dietary isoflavone, biochanin A, which has been recently emerged as a multitargeted and multifunctional guardian of human health. Biochanin A possesses anti-inflammatory, anticancer, neuroprotective, antioxidant, anti-microbial, and hepatoprotective properties. It combats cancer development by inducing apoptosis, inhibition of metastasis and arresting cell cycle via targeting several deregulated signaling pathways of cancer. It fights inflammation by blocking the expression and activity of pro-inflammatory cytokines via modulation of NF-κB and MAPKs. Biochanin A acts as a neuroprotective agent by inhibiting microglial activation and apoptosis of neurons. As biochanin A has potential to modulate several biological networks, thus, it can be anticipated that this therapeutically potent compound might serve as a novel lead for drug development in the near future.

Relevance of Translation Initiation in Diffuse Glioma Biology and its Therapeutic Potential

Cancer cells are continually exposed to environmental stressors forcing them to adapt their protein production to survive. The translational machinery can be recruited by malignant cells to synthesize proteins required to promote their survival, even in times of high physiological and pathological stress. This phenomenon has been described in several cancers including in gliomas. Abnormal regulation of translation has encouraged the development of new therapeutics targeting the protein synthesis pathway. This approach could be meaningful for glioma given the fact that the median survival following diagnosis of the highest grade of glioma remains short despite current therapy. The identification of new targets for the development of novel therapeutics is therefore needed in order to improve this devastating overall survival rate. This review discusses current literature on translation in gliomas with a focus on the initiation step covering both the cap-dependent and cap-independent modes of initiation. The different translation initiation protagonists will be described in normal conditions and then in gliomas. In addition, their gene expression in gliomas will systematically be examined using two freely available datasets. Finally, we will discuss different pathways regulating translation initiation and current drugs targeting the translational machinery and their potential for the treatment of gliomas.

Natural Products and Synthetic Analogs as a Source of Antitumor Drugs

Cancer is a heterogeneous disease and one of the major issues of health concern, especially for the public health system globally. Nature is a source of anticancer drugs with abundant pool of diverse chemicals and pharmacologically active compounds. In recent decade, some natural products and synthetic analogs have been investigated for the cancer treatment. This article presents the utilization of natural products as a source of antitumor drugs.

The Molecular Mechanisms of Plant-Derived Compounds Targeting Brain Cancer

Glioblastoma multiforme (GBM) is one of the most aggressive and malignant forms of brain tumors. Despite recent advances in operative and postoperative treatments, it is almost impossible to perform complete resection of these tumors owing to their invasive and diffuse nature. Several natural plant-derived products, however, have been demonstrated to have promising therapeutic effects, such that they may serve as resources for anticancer drug discovery. The therapeutic effects of one such plant product, n-butylidenephthalide (BP), are wide-ranging in nature, including impacts on cancer cell apoptosis, cell cycle arrest, and cancer cell senescence. The compound also exhibits a relatively high level of penetration through the blood-brain barrier (BBB). Taken together, its actions have been shown to have anti-proliferative, anti-chemoresistance, anti-invasion, anti-migration, and anti-dissemination effects against GBM. In addition, a local drug delivery system for the subcutaneous and intracranial implantation of BP wafers that significantly reduce tumor size in xenograft models, as well as orthotopic and spontaneous brain tumors in animal models, has been developed. Isochaihulactone (ICL), another kind of plant product, possesses a broad spectrum of pharmacological activities, including impacts on cancer cell apoptosis and cell cycle arrest, as well as anti-proliferative and anti-chemoresistance effects. Furthermore, these actions have been specifically shown to have cancer-fighting effects on GBM. In short, the results of various studies reviewed herein have provided substantial evidence indicating that BP and ICH are promising novel anticancer compounds with good potential for clinical applications.

Natural Bioactive Compounds: Alternative Approach to the Treatment of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most frequent, primary malignant brain tumor prevalent in humans. GBM characteristically exhibits aggressive cell proliferation and rapid invasion of normal brain tissue resulting in poor patient prognosis. The current standard of care of surgical resection followed by radiotherapy and chemotherapy with temozolomide is not very effective. The inefficacy of the chemotherapeutic agents may be attributed to the challenges in drug delivery to the tumor. Several epidemiological studies have demonstrated the chemopreventive role of natural, dietary compounds in the development and progression of cancer. Many of these studies have reported the potential of using natural compounds in combination with chemotherapy and radiotherapy as a novel approach for the effective treatment of cancer. In this paper, we review the role of several natural compounds individually and in combination with chemotherapeutic agents in the treatment of GBM. We also assess the potential of drug delivery approaches such as the Gliadel wafers and role of nanomaterial based drug delivery systems for the effective treatment of GBM.

Mechanism study of isoflavones as an anti-retinoblastoma progression agent

Isoflavones, bioactive soy compounds, are known to exhibit anticancer activities. The present study investigated the anticancer activities of isoflavones on human retinoblastoma Y79 cells in vitro and in vivo. An MTT cell viability assay showed that the half maximal inhibitory concentration value of isoflavones against human retinoblastoma Y79 cells is 1.23 ± 0.42 μmol/l. Flow cytometry analysis indicated that isoflavones blocked G1/S progression. Western blot analysis demonstrated that the mammalian target of rapamycin (mTOR) pathway in Y79 cells was inhibited by isoflavones, with a concomitant decrease in cyclin E1, which accounted for the isoflavone-mediated G1 phase arrest. Isoflavones also inhibited human retinoblastoma growth in vivo; western blot analysis showed inhibition of mTOR and downregulation of cyclin E1 in an isoflavone-treated xenograft mouse model. Together, these results illustrate that isoflavones inhibit retinoblastoma tumour growth in vitro and vivo and that inactivation of the mTOR pathway and downregulation of cyclin E1 is involved in this action. The results of this study suggest that isoflavones could be tested as promising anti-retinoblastoma agent.

A fully coupled space-time multiscale modeling framework for predicting tumor growth

Most biological systems encountered in living organisms involve highly complex heterogeneous multi-component structures that exhibit different physical, chemical, and biological behavior at different spatial and temporal scales. The development of predictive mathematical and computational models of multiscale events in such systems is a major challenge in contemporary computational biomechanics, particularly the development of models of growing tumors in humans. The aim of this study is to develop a general framework for tumor growth prediction by considering major biological events at tissue, cellular, and subcellular scales. The key to developing such multiscale models is how to bridge spatial and temporal scales that range from 10^-3 to 10³ mm in space and from 10^-6 to 10⁷ s in time. In this paper, a fully coupled space-time multiscale framework for modeling tumor growth is developed. The framework consists of a tissue scale model, a model of cellular activities, and a subcellular transduction signaling pathway model. The tissue, cellular, and subcellular models in this framework are solved using partial differential equations for tissue growth, agent-based model for cellular events, and ordinary differential equations for signaling transduction pathway as a network at subcellular scale. The model is calibrated using experimental observations. Moreover, this model is biologically-driven from a signaling pathway, volumetrically-consistent between cellular and tissue scale in terms of tumor volume evolution in time, and a biophysically-sound tissue model that satisfies all conservation laws. The results show that the model is capable of predicting major characteristics of tumor growth such as the morphological instability, growth patterns of different cell phenotypes, compact regions of the higher cell density at the tumor region, and the reduction of growth rate due to drug delivery. The predicted treatment outcomes show a reduction in proliferation at different rates in response to different drug dosages. Moreover, the results of several 3D applications to tumor growth and the evolution of cellular and subcellular events are presented.

Resveratrol Potentiates Growth Inhibitory Effects of Rapamycin in PTEN-deficient Lipoma Cells by Suppressing p70S6 Kinase Activity

Patients with phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome and germline mutations in PTEN frequently develop lipomatosis, for which there is no standard treatment. Rapamycin was shown to reduce the growth of lipoma cells with heterozygous PTEN deficiency in vitro, but concomitantly induced an upregulation of AKT phosphorylation. Since it was shown that resveratrol stabilizes PTEN, we asked whether co-incubation with resveratrol could suppress the rapamycin-induced AKT phosphorylation in PTEN-deficient lipoma cells. Resveratrol incubation resulted in decreased lipoma cell viability by inducing G1-phase cell cycle arrest and apoptosis. PTEN expression and AKT phosphorylation were not significantly changed, whereas p70S6 kinase (p70S6K) phosphorylation was reduced in PTEN-deficient lipoma cells after resveratrol incubation. Rapamycin/resveratrol co-incubation significantly decreased viability further at lower doses of resveratrol and resulted in decreased p70S6K phosphorylation compared to rapamycin incubation alone, suggesting that resveratrol potentiated the growth inhibitory effects of rapamycin by reducing p70S6K activation. Both viability and p70S6K phosphorylation of primary PTEN wild-type preadipocytes were less affected compared to PTEN-deficient lipoma cells by equimolar concentrations of resveratrol. These results support the concept of combining chemopreventive natural compounds with mammalian target of rapamycin (mTOR) inhibitors to increase the efficacy of chemotherapeutic drugs for patients suffering from overgrowth syndromes.

mTOR inhibition and levels of the DNA repair protein MGMT in T98G glioblastoma cells

Background

Glioblastoma multiforme (GBM), the most common and most aggressive type of primary adult brain tumour, responds poorly to conventional treatment. Temozolomide (TMZ) chemotherapy remains the most commonly used treatment, despite a large proportion of tumours displaying TMZ resistance. 60% of GBM tumours have unmethylated MGMT promoter regions, resulting in an overexpression of the DNA repair protein O⁶-methylguanine-DNA methyltransferase (MGMT), which is responsible for tumour resistance to TMZ chemotherapy. Tumours also often exhibit hyperactive PI3-kinase/mTOR signalling, which enables them to resynthesise proteins quickly. Since MGMT is a suicide protein that is degraded upon binding to and repairing TMZ-induced O⁶-methylguanine adducts, it has been hypothesized that inhibition of translation via the mTOR signalling pathway could generate a tumour-specific reduction in MGMT protein and increase TMZ sensitivity.

Methods

MGMT was monitored at the post-transcriptional, translational and protein levels, to determine what effect mTOR inhibition was having on MGMT protein expression in vitro.

Results

We show that inhibiting mTOR signalling is indeed associated with acute inhibition of protein synthesis. Western blots show that despite this, relative to loading control proteins, steady state levels of MGMT protein increased and MGMT mRNA was retained in heavy polysomes. Whilst TMZ treatment resulted in maintained MGMT protein levels, concomitant treatment of T98G cells with TMZ and KU0063794 resulted in increased MGMT protein levels without changes in total mRNA levels.

Conclusions

These in vitro data suggest that, counterintuitively, mTOR inhibition may not be a useful adjunct to TMZ therapy and that more investigation is needed before applying mTOR inhibitors in a clinical setting.

The impact of dietary isoflavonoids on malignant brain tumors

Poor prognosis and limited therapeutic options render malignant brain tumors one of the most devastating diseases in clinical medicine. Current treatment strategies attempt to expand the therapeutic repertoire through the use of multimodal treatment regimens. It is here that dietary fibers have been recently recognized as a supportive natural therapy in augmenting the body's response to tumor growth. Here, we investigated the impact of isoflavonoids on primary brain tumor cells. First, we treated glioma cell lines and primary astrocytes with various isoflavonoids and phytoestrogens. Cell viability in a dose-dependent manner was measured for biochanin A (BCA), genistein (GST), and secoisolariciresinol diglucoside (SDG). Dose–response action for the different isoflavonoids showed that BCA is highly effective on glioma cells and nontoxic for normal differentiated brain tissues. We further investigated BCA in ex vivo and in vivo experimentations. Organotypic brain slice cultures were performed and treated with BCA. For in vivo experiments, BCA was intraperitoneal injected in tumor-implanted Fisher rats. Tumor size and edema were measured and quantified by magnetic resonance imaging (MRI) scans. In vascular organotypic glioma brain slice cultures (VOGIM) we found that BCA operates antiangiogenic and neuroprotective. In vivo MRI scans demonstrated that administered BCA as a monotherapy was effective in reducing significantly tumor-induced brain edema and showed a trend for prolonged survival. Our results revealed that dietary isoflavonoids, in particular BCA, execute toxicity toward glioma cells, antiangiogenic, and coevally neuroprotective properties, and therefore augment the range of state-of-the-art multimodal treatment approach.

Inhibition of glioma growth by minocycline is mediated through endoplasmic reticulum stress-induced apoptosis and autophagic cell death

BACKGROUND

We have reported that minocycline (Mino) induced autophagic death in glioma cells. In the present study, we characterize the upstream regulators that control autophagy and switch cell death from autophagic to apoptotic.

METHODS

Western blotting and immunofluorescence were used to detect the expressions of eukaryotic translation initiation factor 2α (eIF2α), transcription factor GADD153 (CHOP), and glucose-regulated protein 78 (GRP78). Short hairpin (sh)RNA was used to knock down eIF2α or CHOP expression. Autophagy was assessed by the conversion of light chain (LC)3-I to LC3-II and green fluorescent protein puncta formation. An intracranial mouse model and bioluminescent imaging were used to assess the effect of Mino on tumor growth and survival time of mice.

RESULTS

The expression of GRP78 in glioma was high, whereas in normal glia it was low. Mino treatment increased GRP78 expression and reduced binding of GRP78 with protein kinase-like endoplasmic reticulum kinase. Subsequently, Mino increased eIF2α phosphorylation and CHOP expression. Knockdown of eIF2α or CHOP reduced Mino-induced LC3-II conversion and glioma cell death. When autophagy was inhibited, Mino induced cell death in a caspase-dependent manner. Rapamycin in combination with Mino produced synergistic effects on LC3 conversion, reduction of the Akt/mTOR/p70S6K pathway, and glioma cell death. Bioluminescent imaging showed that Mino inhibited the growth of glioma and prolonged survival time and that these effects were blocked by shCHOP.

CONCLUSIONS

Mino induced autophagy by eliciting endoplasmic reticulum stress response and switched cell death from autophagy to apoptosis when autophagy was blocked. These results coupled with clinical availability and a safe track record make Mino a promising agent for the treatment of malignant gliomas.

Rapamycin inhibits the growth of glioblastoma

The molecular target of rapamycin (mTOR) is up-regulated in glioblastoma (GBM) and this is associated with the rate of cell growth, stem cell proliferation and disease relapse. Rapamycin is a powerful mTOR inhibitor and strong autophagy inducer. Previous studies analyzed the effects of rapamycin in GBM cell lines. However, to our knowledge, no experiment was carried out to evaluate the effects of rapamycin neither in primary cells derived from GBM patients nor in vivo in brain GBM xenograft. These data are critical to get a deeper insight into the effects of such adjuvant therapy in GBM patients. In the present study, various doses of rapamycin were tested in primary cell cultures from GBM patients. These effects were compared with that obtained by the same doses of rapamycin in GBM cell lines (U87Mg). The effects of rapamycin were also evaluated in vivo, in brain tumors developed from mouse xenografts. Rapamycin, starting at the dose of 10nm inhibited cell growth both in U87Mg cell line and primary cell cultures derived from various GBM patients. When administered in vivo to brain xenografts in nude mice rapamycin almost doubled the survival time of mice and inhibited by more than 95% of tumor volume.

Leucine signaling in the pathogenesis of type 2 diabetes and obesity

Epidemiological evidence points to increased dairy and meat consumption, staples of the Western diet, as major risk factors for the development of type 2 diabetes (T2D). This paper presents a new concept and comprehensive review of leucine-mediated cell signaling explaining the pathogenesis of T2D and obesity by leucine-induced over-stimulation of mammalian target of rapamycin complex 1 (mTORC1). mTORC1, a pivotal nutrient-sensitive kinase, promotes growth and cell proliferation in response to glucose, energy, growth factors and amino acids. Dairy proteins and meat stimulate insulin/insulin-like growth factor 1 signaling and provide high amounts of leucine, a primary and independent stimulator for mTORC1 activation. The downstream target of mTORC1, the kinase S6K1, induces insulin resistance by phosphorylation of insulin receptor substrate-1, thereby increasing the metabolic burden of β-cells. Moreover, leucine-mediated mTORC1-S6K1-signaling plays an important role in adipogenesis, thus increasing the risk of obesity-mediated insulin resistance. High consumption of leucine-rich proteins explains exaggerated mTORC1-dependent insulin secretion, increased β-cell growth and β-cell proliferation promoting an early onset of replicative β-cell senescence with subsequent β-cell apoptosis. Disturbances of β-cell mass regulation with increased β-cell proliferation and apoptosis as well as insulin resistance are hallmarks of T2D, which are all associated with hyperactivation of mTORC1. In contrast, the anti-diabetic drug metformin antagonizes leucine-mediated mTORC1 signaling. Plant-derived polyphenols and flavonoids are identified as natural inhibitors of mTORC1 and exert anti-diabetic and anti-obesity effects. Furthermore, bariatric surgery in obesity reduces increased plasma levels of leucine and other branched-chain amino acids. Attenuation of leucine-mediated mTORC1 signaling by defining appropriate upper limits of the daily intake of leucine-rich animal and dairy proteins may offer a great chance for the prevention of T2D and obesity, as well as other epidemic diseases of civilization with increased mTORC1 signaling, especially cancer and neurodegenerative diseases, which are frequently associated with T2D.

Glioblastoma biomarkers from bench to bedside: advances and challenges

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumour, with few available therapies providing significant improvements in mortality. Biomarkers, which are defined by the National Institutes of Health as 'characteristics that are objectively measured and evaluated as indicators of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention', have the potential to play valuable roles in the diagnosis and treatment of GBM. Although GBM biomarker research is still in its early stages because of the tumour's complex pathophysiology, a number of potential markers have been identified which can be measured in either brain tissue or blood serum. In conjunction with other clinical data, particularly neuroimaging modalities such as MRI, these proteins could contribute to the clinical management of GBM by helping to classify tumours, predict prognosis and assess treatment response. In this article, we review the current understanding of GBM pathophysiology and recent advances in GBM biomarker research, and discuss the potential clinical implications of promising biomarkers. A better understanding of GBM pathophysiology will allow researchers and clinicians to identify optimal biomarkers and methods of interpretation, leading to advances in tumour classification, prognosis prediction and treatment assessment.

Fibroblast growth factor and ornithine decarboxylase 5'UTRs enable preferential expression in human prostate cancer cells and in prostate tumors of PTEN(-/-) transgenic mice

In this study, we have taken advantage of over-expression of eukaryotic translation initiation factor 4E (eIF4E) in prostate cancer cells to design a viral-based targeting system of prostate cancer. Three different lengths of 5'-untranslated regions (5'UTRs) derived from either fibroblast growth factor-2 (FU-FGF2-GW) or ornithine decarboxylase (FU-ODC149-GW and FU-ODC274-GW) were inserted upstream of enhanced green fluorescent protein (GFP) gene in a lentiviral backbone. Both nonmalignant control (PNT1B and BPH-1) and neoplastic (LNCaP, C4-2, DU145 and PC-3) prostate cell lines were transfected with each plasmid or virus alone, or in the presence of siRNA against eIF4E, and their expression was monitored via GFP protein levels. Two 5'UTRs (FU-FGF2-GW and FU-ODC-GW) were selected as being most sensitive to eIF4E status. Lentiviruses containing these sequences were injected directly into the prostates of PTEN(-/-) (tumor-bearing) and control mice. Immunofluorescence data and western blot analyses determined that a lentivirus containing a 5'UTR derived from FGF-2 is the best candidate for directing selective gene expression in the prostate tumors of PTEN(-/-) mice in vivo. This study demonstrates that judicious selection of a complex 5'UTR can enhance selective targeting of viral-based gene therapies for prostate cancer.

Network target for screening synergistic drug combinations with application to traditional Chinese medicine

BACKGROUND

Multicomponent therapeutics offer bright prospects for the control of complex diseases in a synergistic manner. However, finding ways to screen the synergistic combinations from numerous pharmacological agents is still an ongoing challenge.

RESULTS

In this work, we proposed for the first time a "network target"-based paradigm instead of the traditional "single target"-based paradigm for virtual screening and established an algorithm termed NIMS (Network target-based Identification of Multicomponent Synergy) to prioritize synergistic agent combinations in a high throughput way. NIMS treats a disease-specific biological network as a therapeutic target and assumes that the relationship among agents can be transferred to network interactions among the molecular level entities (targets or responsive gene products) of agents. Then, two parameters in NIMS, Topology Score and Agent Score, are created to evaluate the synergistic relationship between each given agent combinations. Taking the empirical multicomponent system traditional Chinese medicine (TCM) as an illustrative case, we applied NIMS to prioritize synergistic agent pairs from 63 agents on a pathological process instanced by angiogenesis. The NIMS outputs can not only recover five known synergistic agent pairs, but also obtain experimental verification for synergistic candidates combined with, for example, a herbal ingredient Sinomenine, which outperforms the meet/min method. The robustness of NIMS was also showed regarding the background networks, agent genes and topological parameters, respectively. Finally, we characterized the potential mechanisms of multicomponent synergy from a network target perspective.

CONCLUSIONS

NIMS is a first-step computational approach towards identification of synergistic drug combinations at the molecular level. The network target-based approaches may adjust current virtual screen mode and provide a systematic paradigm for facilitating the development of multicomponent therapeutics as well as the modernization of TCM.