Apoptosis induction in human glioblastoma multiforme T98G cells upon temozolomide and quercetin treatment

Natural compounds as lactate dehydrogenase inhibitors: potential therapeutics for lactate dehydrogenase inhibitors-related diseases

Lactate dehydrogenase (LDH) is a crucial enzyme involved in energy metabolism and present in various cells throughout the body. Its diverse physiological functions encompass glycolysis, and its abnormal activity is associated with numerous diseases. Targeting LDH has emerged as a vital approach in drug discovery, leading to the identification of LDH inhibitors among natural compounds, such as polyphenols, alkaloids, and terpenoids. These compounds demonstrate therapeutic potential against LDH-related diseases, including anti-cancer effects. However, challenges concerning limited bioavailability, poor solubility, and potential toxicity must be addressed. Combining natural compounds with LDH inhibitors has led to promising outcomes in preclinical studies. This review highlights the promise of natural compounds as LDH inhibitors for treating cancer, cardiovascular, and neurodegenerative diseases.

Exploring the potential of quercetin/aspirin-loaded chitosan nanoparticles coated with Eudragit L100 in the treatment of induced-colorectal cancer in rats

Growing evidence suggests quercetin and aspirin may have anticancer properties, notably in the case of colorectal cancer. The goal of this study was to create Pluronic F127 and polyethylene glycol4000 solid dispersion-loaded chitosan nanoparticles for colonic quercetin and aspirin delivery. In 1:1 polymeric stoichiometric ratio, solubility and complex formation were verified. Solid dispersion-loaded chitosan nanoparticles with a diameter of 244.45 ± 8.5 nm, a surface charge of 34.1 ± 3.3 mV, and encapsulation effectiveness of 76.3 ± 4.3% were generated under ideal conditions. In some cases, coating with Eudragit L100 resulted in a decrease in zeta potential and an increase in particle size. The coated formulation released the actives in a pH-dependent manner, considering their physicochemical features. Surprisingly, when compared to the actives' suspension and uncoated formulation, the coated formulation had greater anti-inflammatory efficacy, with a substantial reduction of PGE2 and IL-8 production in colonic tissues (16.9 ± 7.9 ng/g tissue and 134.9 ± 10.1 pg/g tissue, respectively). It also reversed most of the dimethyl hydrazine-induced histological alterations in the colon. It also demonstrated a greater reduction in TNF expression in colonic tissues. As a result, Eudragit L100-coated QT/AS-loaded chitosan nanoparticles are suggested to provide a potential platform for colonic delivery of quercetin and aspirin.

Quercetin and Its Nano-Formulations for Brain Tumor Therapy—Current Developments and Future Perspectives for Paediatric Studies

The development of efficient treatments for tumors affecting the central nervous system (CNS) remains an open challenge. Particularly, gliomas are the most malignant and lethal form of brain tumors in adults, causing death in patients just over 6 months after diagnosis without treatment. The current treatment protocol consists of surgery, followed using synthetic drugs and radiation. However, the efficacy of these protocols is associated with side effects, poor prognosis and with a median survival of fewer than two years. Recently, many studies were focused on applying plant-derived products to manage various diseases, including brain cancers. Quercetin is a bioactive compound derived from various fruits and vegetables (asparagus, apples, berries, cherries, onions and red leaf lettuce). Numerous in vivo and in vitro studies highlighted that quercetin through multitargeted molecular mechanisms (apoptosis, necrosis, anti-proliferative activity and suppression of tumor invasion and migration) effectively reduces the progression of tumor cells. This review aims to summarize current developments and recent advances of quercetin’s anticancer potential in brain tumors. Since all reported studies demonstrating the anti-cancer potential of quercetin were conducted using adult models, it is suggested to expand further research in the field of paediatrics. This could offer new perspectives on brain cancer treatment for paediatric patients.

Nitrogen Fertilization and Solvents as Factors Modifying the Antioxidant and Anticancer Potential of Arnica montana L. Flower Head Extracts

Arnica montana L. is one of Europe's endemic endangered medicinal plants, with diverse biological activities commonly used in medicine, pharmacy, and cosmetics. Its flower heads are a rich source of raw material, with antibacterial, antifungal, antiseptic, anti-inflammatory, antiradical, antioxidant, and antitumor properties. The objective of the present study was (i) to characterize the chemical composition of flower heads of A. montana plants cultivated under nitrogen fertilization, (ii) to identify the impact of the nitrogen fertilization and extraction method (water, ethanol) on the antioxidant activity of extracts, and (iii) to determine the role of different nitrogen doses applied during plant cultivation and different extraction methods in the anticancer activity of the extracts through analysis of apoptosis and autophagy induction in HT29, HeLa, and SW620 cell lines. The present study shows that nitrogen is a crucial determinant of the chemical composition of arnica flower heads and the antioxidant and anticancer activity of the analyzed extracts. Nitrogen fertilization can modify the composition of pharmacologically active substances (sesquiterpene lactones, flavonoids, essential oil) in Arnicae flos. The content of sesquiterpene lactones, flavonoids, and essential oil increased with the increase in the nitrogen doses to 60 kg N ha^-1 by 0.66%, 1.45%, and 0.27%, respectively. A further increase in the nitrogen dose resulted in a decrease in the content of the analyzed secondary metabolites. Varied levels of nitrogen application can be regarded as a relevant way to modify the chemical composition of arnica flower heads and to increase the anticancer activity, which was confirmed by the increase in the level of apoptosis with the increase in fertilization to a level of 60 kg N ha^-1. The fertilization of arnica plants with low doses of nitrogen (30 and 60 kg N ha^-1) significantly increased the LOX inhibition ability of the ethanol extracts. The present study is the first report on the anticancer activity of A. montana water extracts, with emphasis on the role of water as a solvent. In further studies of factors modifying the quality of Arnicae flos, attention should be paid to the simultaneous use of nitrogen and other microelements to achieve synergistic results and to the possibility of a more frequent use of water as a solvent in studies on the biological activity of A. montana extracts.

Drug-herb combination therapy in cancer management

Cancer is the second leading cause of fatality all over the world. Various unwanted side effects are being reported with the use of conventional chemotherapy. The plant derived bioactive compounds are the prominent alternative medicinal approach for reduction of chemotherapy associated side effects. The data is collected from Pubmed, Sci-hub, Google scholar, and Research gate were systematically searched up to year 2020. Several herbal drugs have been investigated and found with grateful anti-cancer potentials hence, it can be used in combination with chemotherapy for the depletion of associated side-effects. Herbal drugs and their extracts contain a mixture of active ingredients, which show interactions within themselves and along with chemotherapeutic agents to show either synergistic or antagonistic therapeutic effects. Therefore, it is necessary to develop alternative treatment to control chemotherapy associated side-effects. In this review, we discussed some of the significant chemical compounds, which could be efficient against cancer. This review focuses on the different herbal drugs that play an important role in the treatment of cancer and its associated side-effects. This study aimed to evaluate the efficacy of herbal treatment in combination with chemotherapy for cancer treatment.

The Role of Hsp27 in Chemotherapy Resistance

Heat shock protein (Hsp)-27 is a small-sized, ATP-independent, chaperone molecule that is overexpressed under conditions of cellular stress such as oxidative stress and heat shock, and protects proteins from unfolding, thus facilitating proteostasis and cellular survival. Despite its protective role in normal cell physiology, Hsp27 overexpression in various cancer cell lines is implicated in tumor initiation, progression, and metastasis through various mechanisms, including modulation of the SWH pathway, inhibition of apoptosis, promotion of EMT, adaptation of CSCs in the tumor microenvironment and induction of angiogenesis. Investigation of the role of Hsp27 in the resistance of various cancer cell types against doxorubicin, herceptin/trastuzumab, gemcitabine, 5-FU, temozolomide, and paclitaxel suggested that Hsp27 overexpression promotes cancer cell survival against the above-mentioned chemotherapeutic agents. Conversely, Hsp27 inhibition increased the efficacy of those chemotherapy drugs, both in vitro and in vivo. Although numerous signaling pathways and molecular mechanisms were implicated in that chemotherapy resistance, Hsp27 most commonly contributed to the upregulation of Akt/mTOR signaling cascade and inactivation of p53, thus inhibiting the chemotherapy-mediated induction of apoptosis. Blockage of Hsp27 could enhance the cytotoxic effect of well-established chemotherapeutic drugs, especially in difficult-to-treat cancer types, ultimately improving patients’ outcomes.

Quercetin and Glioma: Which signaling pathways are involved?

Abstract:

Gliomas are the most common brain tumors. These tumors commonly exhibit continuous growth without invading surrounding brain tissues. Dominant remedial approaches suffer limited therapy and survival rates. Although some progress has been made in conventional glioma treatments, these breakthroughs have not yet proven sufficient for treating this malignancy. The remedial options are limited given gliomas' aggressive metastasis and drug resistance. Quercetin, a flavonoid, is an anti-oxidative, anti-allergic, antiviral, anti-inflammatory, and anticancer compound. Multiple lines of evidence have shown that Quercetin has anti-tumor effects, documenting this natural compound exerts its pharmacological effects by targeting a variety of cellular and molecular processes, i.e., apoptosis, metastasis, and autophagy. Herein, we summarize various cellular and molecular pathways that are affected by Quercetin in gliomas.

A Preliminary Study of the Effect of Quercetin on Cytotoxicity, Apoptosis, and Stress Responses in Glioblastoma Cell Lines

A growing body of evidence indicates that dietary polyphenols show protective effects against various cancers. However, little is known yet about their activity in brain tumors. Here we investigated the interaction of dietary flavonoid quercetin (QCT) with the human glioblastoma A172 and LBC3 cell lines. We demonstrated that QCT evoked cytotoxic effect in both tested cell lines. Microscopic observations, Annexin V-FITC/PI staining, and elevated expression and activity of caspase 3/7 showed that QCT caused predominantly apoptotic death of A172 cells. Further analyses confirmed enhanced ROS generation, deregulated expression of SOD1 and SOD2, depletion of ATP levels, and an overexpression of CHOP, suggesting the activation of oxidative stress and ER stress upon QCT exposure. Finally, elevated expression and activity of caspase 9, indicative of a mitochondrial pathway of apoptosis, was detected. Conversely, in LBC3 cells the pro-apoptotic effect was observed only after 24 h incubation with QCT, and a shift towards necrotic cell death was observed after 48 h of treatment. Altogether, our data indicate that exposure to QCT evoked cell death via activation of intrinsic pathway of apoptosis in A172 cells. These findings suggest that QCT is worth further investigation as a potential pharmacological agent in therapy of brain tumors.

Quercetin-loaded platelets as a potential targeted therapy for glioblastoma multiforme cell line U373-MG

Over the globe, the incidence of glioblastoma multiforme (GM) is very low, that is, 1-4 cases per 100,000, but it is fatal and cancer grows very fast inside the brain tissues, namely astrocytes and oligodendrocytes. Because of the rapid growth, it is difficult to halt the dissemination of tumor in adjacent tissues. Although temozolomide (TMZ) is a currently approved standard of care, it develops resistance over the period. Therefore, there is a need to develop a novel drug delivery system. In this work, authors have developed platelets as drug delivery carriers-loaded with quercetin (QCT) for targeting GM. The effect of QCT and QCT-platelet was assessed on the U373-MG cell line. Natural human platelets were used as carriers for drug loading and drug delivery. Platelets possess an open canalicular system that allows the uptake of drug molecules in the platelet cytoplasm. The study showed that the maximum encapsulation efficiency of QCT-platelet was 93.96 ± 0.12% and the maximum drug release in 24 h was 76.26 ± 0.13% in-vitro at pH 5.5 that mimics the tumor microenvironment. In this work, there is a three-fold enhancement of solubility of QCT. The cytotoxic activity of QCT-platelets was studied in the U373-MG human astrocytoma glioblastoma cell line and the cell viability was 14.52 ± 1.53% after 48 h. Thus, platelets were proved as good carriers for therapeutic moieties and can be effectively used to target the glioblastoma tumor in the near future.

Harmine Augments the Cytotoxic and Anti-invasive Potential of Temozolomide Against Glioblastoma Multiforme Cells

Background: Glioblastoma multiforme (GBM) is considered the deadliest human cancer. Temozolomide is now a part of postresection standard chemotherapy for this type of cancer. Unfortunately, resistance to temozolomide is a major obstacle to treatment success. Combination therapy with natural anticancer agents increases the activity of temozolomide against cancer cells. Objectives: This study aimed to assess the effects of temozolomide in combination with harmine against GBM cells. Methods: Cancer cells were treated with temozolomide and/or harmine. After 24, 48, 72, and 96 h, the viability of the cells was assessed by the MTT test. The combination index and dose reduction index were determined by CompuSyn software. Tumor invasion potential was investigated by evaluating cell migration, invasion, and adhesion. The real-time PCR technique was done to study the expression pattern of two genes involved in cancer cell invasion. Statistical analysis was performed using one-way analysis of variance and Tukey’s post-hoc test, and differences were considered non-significant at P > 0.05. Results: After treatment with temozolomide, cell viability showed a concentration- and time-dependent decrease, and the cells’ survival rate decreased. The combination of temozolomide and harmine had a synergistic effect. Also, temozolomide and/or harmine treatment decreased cancer cells’ migration, invasion, and adhesion potentials, as well as the expression of metalloproteinases 2 and 9 in T98G cells. Conclusions: The combination of temozolomide and harmine can be promising for the successful treatment of GBM.

Combinatorial Effect of Temozolomide and Naringenin in Human Glioblastoma Multiforme Cell Lines

Glioblastoma multiforme (GBM) is a grade IV, lethal, and the most common type of brain tumor. GBM can acquire resistance to temozolomide (TMZ) recommended for its treatment. Naringenin (NAG), a flavonoid generally found in grapefruit, has antioxidant, anti-proliferative, and anti-inflammatory properties. It has been reported that phytochemicals can reduce resistance and improve the efficacy of a chemo-resistant drug. The combinatorial effect of TMZ and NAG on cell proliferation was evaluated using 3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT) assay, and the apoptosis in the U87MG and LN229 GBM cells were evaluated by change in fluorescence intensity. The effect of NAG and TMZ on anchorage-independent single-cell colony formation and cell migration was investigated. NAG and TMZ demonstrated enhanced cytotoxic effects on U87MG and LN229 cell lines. The combination index value being less than one indicated the synergistic action of the two drugs in restricting the growth of the cells. The NAG and TMZ together resulted in higher fluorescence intensity as compared to the alone drug. Further, the study showed a marked reduction in the migration of the cells and the formation of a single cell colony.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1952438.

Bioactive Compounds with Antiglioma Activity from Marine Species

The search for new chemical compounds with antitumor pharmacological activity is a necessary process for creating more effective drugs for each specific malignancy type. This review presents the outcomes of screening studies of natural compounds with high anti-glioma activity. Despite significant advances in cancer therapy, there are still some tumors currently considered completely incurable including brain gliomas. This review covers the main problems of the glioma chemotherapy including drug resistance, side effects of common anti-glioma drugs, and genetic diversity of brain tumors. The main emphasis is made on the characterization of natural compounds isolated from marine organisms because taxonomic diversity of organisms in seawaters significantly exceeds that of terrestrial species. Thus, we should expect greater chemical diversity of marine compounds and greater likelihood of finding effective molecules with antiglioma activity. The review covers at least 15 classes of organic compounds with their chemical formulas provided as well as semi-inhibitory concentrations, mechanisms of action, and pharmacokinetic profiles. In conclusion, the analysis of the taxonomic diversity of marine species containing bioactives with antiglioma activity is performed noting cytotoxicity indicators and to the tumor cells in comparison with similar indicators of antitumor agents approved for clinical use as antiglioblastoma chemotherapeutics.

LY294002 and sorafenib as inhibitors of intracellular survival pathways in the elimination of human glioma cells by programmed cell death

Gliomas are aggressive brain tumors with very high resistance to chemotherapy throughout the overexpression of multiple intracellular survival pathways. Therefore, the aim of the present study was to investigate for the first time the anticancer activity of LY294002, phosphatidylinositol 3-kinase (PI3K) inhibitor and sorafenib, and rapidly accelerated fibrosarcoma kinase (Raf) inhibitor in the elimination of human glioma cells by programmed cell death. MOGGCCM (anaplastic astrocytoma, III) and T98G (glioblastoma multiforme, IV) cell lines incubated with LY294002 and/or sorafenib were used in the experiments. Simultaneous treatment with both drugs was more effective in the elimination of cancer cells on the way of apoptosis with no significant necrotic effect than single application. It was correlated with decreasing the mitochondrial membrane potential and activation of caspase 3 and 9. The expression of Raf and PI3K was also inhibited. Blocking of those kinases expression by specific siRNA revealed significant apoptosis induction, exceeding the level observed after LY294002 and sorafenib treatment in non-transfected lines but only in MOGGCCM cells. Our results indicated that combination of LY294002 and sorafenib was very efficient in apoptosis induction in glioma cells. Anaplastic astrocytoma cells turned out to be more sensitive for apoptosis induction than glioblastoma multiforme after blocking PI3K and Raf expression with siRNA.

Novel quercetin encapsulated chitosan functionalized copper oxide nanoparticles as anti-breast cancer agent via regulating p53 in rat model

This study was designed to present a new quercetin encapsulated chitosan functionalized copper oxide nanoparticle (CuO-ChNPs-Q) and assessed its anti-breast cancer activity both in vitro and in vivo. The CuO-ChNPs-Q may act as anti-proliferating agent against DMBA-induced mammary carcinoma in female rats. The CuONPs was functionalized with chitosan then quercetin was conjugated with them producing CuO-ChNPs-Q, then characterized. The in vitro anti-proliferating activity of the CuO-ChNPs-Q was evaluated against three human cell line. Then, the anti-breast cancer effect of the CuO-ChNPs-Q was assessed against DMBA-induction compared to both CuONPs and Q in female rat model. The in vitro results proved the potent anticancer activity of the CuO-ChNPs-Q compared to CuONPs and quercetin. The in vivo data showed significant reduction in breast tumors of DMBA-induced rats treated with CuO-ChNPs-Q compared to CuONPs and Q. The CuO-ChNPs-Q treatment had induced apoptosis via increased p53 gene, arrested the cell-cycle, and increased both cytochrome c and caspase-3 levels leading to mammary carcinoma cell death. Also, the CuO-ChNPs-Q treatment had suppressed the PCNA gene which decreased the proliferation of the mammary carcinoma cells. In conclusion, the CuO-ChNPs-Q might be a promising chemotherapeutic agent for treatment of breast cancer with a minimal toxicity on vital organs.

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.

Involvement of PI3K Pathway in Glioma Cell Resistance to Temozolomide Treatment

The aim of the study was to investigate the anticancer potential of LY294002 (PI3K inhibitor) and temozolomide using glioblastoma multiforme (T98G) and anaplastic astrocytoma (MOGGCCM) cells. Apoptosis, autophagy, necrosis, and granules in the cytoplasm were identified microscopically (fluorescence and electron microscopes). The mitochondrial membrane potential was studied by flow cytometry. The activity of caspases 3, 8, and 9 and Akt was evaluated fluorometrically, while the expression of Beclin 1, PI3K, Akt, mTOR, caspase 12, and Hsp27 was determined by immunoblotting. SiRNA was used to block Hsp27 and PI3K expression. Cell migration and localization of Hsp27 were tested with the wound healing assay and immunocytochemistry, respectively. LY294002 effectively diminished the migratory potential and increased programmed death of T98G and MOGGCCM. Autophagy was dominant in MOGGCCM, while apoptosis was dominant in T98G. LY294002 with temozolomide did not potentiate cell death but redirected autophagy toward apoptosis, which was correlated with ER stress. A similar effect was observed after blocking PI3K expression with siRNA. Transfection with Hsp27 siRNA significantly increased apoptosis related to ER stress. Our results indicate that inhibition of the PI3K/Akt/mTOR pathway sensitizes glioma cells to apoptosis upon temozolomide treatment, which was correlated with ER stress. Hsp27 increases the resistance of glioma cells to cell death upon temozolomide treatment.

Oxidative Stress Mediated Cytotoxicity, Cell Cycle Arrest, and Apoptosis Induced by Rosa damascena in Human Cervical Cancer HeLa Cells

Rosa damascena Mill (Damask rose), belonging to the Rosaceae family, is known for medicinal purposes in traditional medicine system. However, its anticancer activity has not been studied yet in detail. Herein, we aimed to investigate the cytotoxic effects of R. damascena hexane (RA-HE) and methanolic (RA-ME) extracts against human breast (MCF-7), lung epithelial (A-549), and cervical (HeLa) cancer cells. The RA-HE and RA-ME showed more potent cytotoxic effects against HeLa cells with an IC₅₀ of 819.6 and 198.4 μg/ml, respectively. Further, cytotoxic concentrations of most effective extract (RA-ME) were used to evaluate the mechanism of cytotoxicity involved in HeLa cells. A concentration-dependent induction of lipid peroxidation (LPO) and reduction of glutathione (GSH) in HeLa cells treated with 250-1000 μg/ml of RA-ME confirms the association of oxidative stress. We also detected a noteworthy increase in reactive oxygen species (ROS) production and a decline in mitochondrial membrane potential (MMP) level in RA-ME-exposed HeLa cells. Flow cytometric data showed a strong dose-response relationship in cell cycle analysis between subG1 phase in HeLa cells and RA-ME treatment. Similarly, a concentration-dependent increase was recorded with Annexin V assay in HeLa cells going to late apoptosis. In conclusion, our findings suggest that RA-ME-induced cytotoxicity and apoptosis in HeLa cells are mediated by oxidative stress.

Resveratrol increases the sensitivity of breast cancer MDA-MB-231 cell line to cisplatin by regulating intrinsic apoptosis

OBJECTIVES

Breast cancer is one of the most common types of cancer. Chemotherapeutic agents used during treatment induce cytotoxic effects also on normal cells in the tissues. Anti-oxidants used in combination with chemotherapeutic agents have been shown to reduce toxicity on normal cells to a minimum, and some anti-oxidant substances have chemotherapeutic effects. Cisplatin (CDDP) is a platinum class drug that is used clinically in the treatment of many cancers. Resveratrol (RSV) is a natural polyphenol with potent anti-oxidant and anticancer properties. In this study, we aimed to investigate apoptotic effects of using cisplatin and RSV alone or in combined treatment of MDA-MB-231 cells.

MATERIALS AND METHODS

The cytotoxic effects of the drugs on MDA-MB-231 cells were determined by MTT method. Subsequently, the change in CDDP-induced apoptotic effect after RSV addition was examined using the AnnexinV FITC labeling, and TUNEL staining method. Activation of caspase-9, -3 in MDA-MB-231 cells was measured by flow cytometer. The mitochondrial membrane potential (MMP), the major factor on the intrinsic pathway, was measured using flowcytometry.

RESULTS

The combined dose (23 μM CDDP + 72 μM RSV) produced more cytotoxicity than the agents used alone, leading to early apoptosis (8.2%), 31% depolarization, and 23% DNA fragmentation. Caspase-9 was found to be 30.5% in this combined group and caspase-3 was 26.3%.

CONCLUSION

RSV, an effective anti-oxidant, and CDDP as an effective drug in cancer treatment, were found to increase apoptosis when given in the MDA-MB-231 cell.

Neuroprotective Effects of Quercetin in Pediatric Neurological Diseases

Oxidative stress is a crucial event underlying several pediatric neurological diseases, such as the central nervous system (CNS) tumors, autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Neuroprotective therapy with natural compounds used as antioxidants has the potential to delay, ameliorate or prevent several pediatric neurological diseases. The present review provides an overview of the most recent research outcomes following quercetin treatment for CNS tumors, ASD and ADHD as well as describes the potential in vitro and in vivo ameliorative effect on oxidative stress of bioactive natural compounds, which seems like a promising future therapy for these diseases. The neuroprotective effects of quercetin against oxidative stress can also be applied in the management of several neurodegenerative disorders with effects such as anti-cancer, anti-inflammatory, anti-viral, anti-obesity and anti-microbial. Therefore, quercetin appears to be a suitable adjuvant for therapy against pediatric neurological diseases.

Antiglioma Potential of Coumarins Combined with Sorafenib

Coumarins, which occur naturally in the plant kingdom, are diverse class of secondary metabolites. With their antiproliferative, chemopreventive and antiangiogenetic properties, they can be used in the treatment of cancer. Their therapeutic potential depends on the type and location of the attachment of substituents to the ring. Therefore, the aim of our study was to investigate the effect of simple coumarins (osthole, umbelliferone, esculin, and 4-hydroxycoumarin) combined with sorafenib (specific inhibitor of Raf (Rapidly Accelerated Fibrosarcoma) kinase) in programmed death induction in human glioblastoma multiforme (T98G) and anaplastic astrocytoma (MOGGCCM) cells lines. Osthole and umbelliferone were isolated from fruits: Mutellina purpurea L. and Heracleum leskowii L., respectively, while esculin and 4-hydroxycoumarin were purchased from Sigma Aldrich (St. Louis, MO, USA). Apoptosis, autophagy and necrosis were identified microscopically after straining with specific fluorochromes. The level of caspase 3, Beclin 1, PI3K (Phosphoinositide 3-kinase), and Raf kinases were estimated by immunoblotting. Transfection with specific siRNA (small interfering RNA) was used to block Bcl-2 (B-cell lymphoma 2), Raf, and PI3K expression. Cell migration was tested with the wound healing assay. The present study has shown that all the coumarins eliminated the MOGGCCM and T98G tumor cells mainly via apoptosis and, to a lesser extent, via autophagy. Osthole, which has an isoprenyl moiety, was shown to be the most effective compound. Sorafenib did not change the proapoptotic activity of this coumarin; however, it reduced the level of autophagy. At the molecular level, the induction of apoptosis was associated with a decrease in the expression of PI3K and Raf kinases, whereas an increase in the level of Beclin 1 was observed in the case of autophagy. Inhibition of the expression of this protein by specific siRNA eliminated autophagy. Moreover, the blocking of the expression of Bcl-2 and PI3K significantly increased the level of apoptosis. Osthole and sorafenib successfully inhibited the migration of the MOGGCCM and T98G cells.

Endothelial-Tumor Cell Interaction in Brain and CNS Malignancies

Glioblastoma and other brain or CNS malignancies (like neuroblastoma and medulloblastoma) are difficult to treat and are characterized by excessive vascularization that favors further tumor growth. Since the mean overall survival of these types of diseases is low, the finding of new therapeutic approaches is imperative. In this review, we discuss the importance of the interaction between the endothelium and the tumor cells in brain and CNS malignancies. The different mechanisms of formation of new vessels that supply the tumor with nutrients are discussed. We also describe how the tumor cells (TC) alter the endothelial cell (EC) physiology in a way that favors tumorigenesis. In particular, mechanisms of EC-TC interaction are described such as (a) communication using secreted growth factors (i.e., VEGF, TGF-β), (b) intercellular communication through gap junctions (i.e., Cx43), and (c) indirect interaction via intermediate cell types (pericytes, astrocytes, neurons, and immune cells). At the signaling level, we outline the role of important mediators, like the gasotransmitter nitric oxide and different types of reactive oxygen species and the systems producing them. Finally, we briefly discuss the current antiangiogenic therapies used against brain and CNS tumors and the potential of new pharmacological interventions that target the EC-TC interaction.

Oleamide Induces Cell Death in Glioblastoma RG2 Cells by a Cannabinoid Receptor-Independent Mechanism

The endocannabinoid system has been associated with antiproliferative effects in several types of tumors through cannabinoid receptor-mediated cell death mechanisms. Oleamide (ODA) is a CB1/CB2 agonist associated with cell growth and migration by adhesion and/or ionic signals associated with Gap junctions. Antiproliferative mechanisms related to ODA remain unknown. In this work, we evaluated the effects of ODA on cell viability and morphological changes in a rat RG2 glioblastoma cell line and compared these effects with primary astrocyte cultures from 8-day postnatal rats. RG2 and primary astrocyte cultures were treated with ODA at increasing concentrations (25, 50, 100, and 200 μM) for different periods of time (12, 24, and 48 h). Changes in RG2 cell viability and morphology induced by ODA were assessed by viability/mitochondrial activity test and phase contrast microscopy, respectively. The ratios of necrotic and apoptotic cell death, and cell cycle alterations, were evaluated by flow cytometry. The roles of CB1 and CB2 receptors on ODA-induced changes were explored with specific receptor antagonists. ODA (100 μM) induced somatic damage, detachment of somatic bodies, cytoplasmic polarization, and somatic shrinkage in RG2 cells at 24 and 48 h. In contrast, primary astrocytes treated at the same ODA concentrations exhibited cell aggregation but not cell damage. ODA (100 μM) increased apoptotic cell death and cell arrest in the G1 phase at 24 h in the RG2 line. The effects induced by ODA on cell viability of RG2 cells were independent of CB1 and CB2 receptors or changes in intracellular calcium transient. Results of this novel study suggest that ODA exerts specific antiproliferative effects on RG2 glioblastoma cells through unconventional apoptotic mechanisms not involving canonical signals.

Coumarins modulate the anti-glioma properties of temozolomide

In the recent years, coumarin bioactive compounds have been identified to posess anticancer properties. Therefore, the aim of the present study was to investigate for the first time the efficacy of osthole, umbelliferone, esculin, and 4-hydroxycoumarin, alone and in combination with Temozolomide, in the elimination of deadly brain tumors, anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) cells via programmed death. Our results indicated that osthole, umbelliferone, esculin, and 4-hydroxycoumarin initiated mainly apoptosis in the T98G and MOGGCCM cells. Osthole was the most effective. It also initiated autophagy in a small percentage of the cell population. The co-incubation with Temozolomide did not increase the pro-apoptotic potential of natural compounds but decreased the level of autophagy in the T98G cells. Apoptosis was associated with reduced mitochondrial membrane potential, activation of caspase 3, inhibition of Bcl-2 expression and the presence of a Bcl-2/Beclin 1. Blocking of Bcl-2 expression resulted in promotion of apoptosis, but not autophagy, in the MOGGCCM and T98G lines. It also sensitized astrocytoma cells, but not GBM, to the combined osthole and TMZ treatment, which was correlated with a reduced level of Beclin 1 and increased expression of caspase 3. Osthole and TMZ, alone and in combination, inhibited the migratory phenotype of the GBM and AA cells. In summary, our results indicated that osthole effectively eliminated glioma cells via apoptosis, what was correlated with Bcl-2/Beclin 1 complex formation. Considering the anti-migratory effect, osthole and Temozolomide display antiglioma potential but it needs further extensive studies.

Quercetin: A promising phytochemical for the treatment of glioblastoma multiforme

Quercetin, a plant-derived flavonoid, is known for its antitumor and antiproliferative activities. Glioblastoma multiforme (GBM), as a highly aggressive cerebrum tumor, has a poor prognosis that is approximately 12 months despite standard therapy. Therefore, because of the low effectiveness of the current therapeutic strategies, additional medications in combination with chemotherapy and radiotherapy are needed, which could improve the prognosis of GBM patients. Multiple lines of evidence have shown that quercetin regulates many proteins involved in the cellular signal transduction in GBM. In this review, recent findings on the targeting of particular signaling pathways by quercetin and the subsequent effect on the pathogenesis of GBM are presented and discussed.

Micro-RNA29b enhances the sensitivity of glioblastoma multiforme cells to temozolomide by promoting autophagy

To explore whether or not aberrant expression of miR-29b in glioblastoma multiforme (GBM) cells was associated with temozolomide (TMZ) resistance and to elucidate potential underlying mechanisms. Upregulation of miR-29 in GBM cells was achieved by transfecting miR-29b mimics. Changes in cell viability were measured by using CCK-8 assays. Flow cytometry and TUNEL assays were used to quantify the number of apoptotic cells. The expression levels of apoptosis-related proteins as well as autophagy-associated proteins, and the expression levels of both apoptotic and autophagic genes were determined by Western blotting. Autophagy flux was monitored by transfecting mRFP-GFP-LC3 adenovirus. We halted autophagy by introducing Atg 5-specific siRNA or the autophagy inhibitor Bafilomycin A1 (Baf-A1). We also employed a GBM xenograft mice model to confirm the role of miR-29b in vivo. miR-29b overexpression induced inhibition of cell viability, and also induced apoptosis and autophagy in U251 and U87MG cells. Furthermore, upregulation of miR-29b was able to potentiate the level of antitumor activity of TMZ against tested cells. We also found that autophagy induced by miR-29b, at least partially, contributed to the increase of TMZ sensitivity in GBM cells. As was evidenced by blockade of autophagy, the application of Atg 5 siRNA or Baf-A1 was able to significantly reverse these effects. Consistent with observations in vitro, findings of in vivo assessment also confirmed that overexpression of miR-29b was able to effectively halt tumor growth and enhance the antitumor activity of TMZ. miR-29b potentiates TMZ sensitivity against GBM cells by inducing autophagy and the combined use of miR-29 mimic and TMZ might represent a potential therapeutic strategy for GBM patients.

Chemical Characteristics and Anticancer Activity of Essential Oil from Arnica Montana L. Rhizomes and Roots

Arnica montana L. is a medicinal plant with diverse biological activities commonly used in pharmacy and cosmetics. The attributes of A. montana are mainly related to the concentration and chemical composition of essential oils (EOs). Therefore, the objective of this study was to characterize the chemical composition of EOs derived from A. montana rhizomes and roots taking into account the age of the plants and to investigate the effect of the analyzed EOs on induction of apoptosis, necrosis, and autophagy in human glioblastoma multiforme T98G and anaplastic astrocytoma MOGGCCM cell lines. Rhizomes and roots of mountain arnica were harvested at the end of the third and fourth vegetation periods. The chemical composition of essential oils was determined with the GC–MS technique. Among the 37 components of the essential oil of A. montana, 2,5-dimethoxy-p-cymene (46.47%–60.31%), 2,6-diisopropylanisole (14.48%–23.10%), thymol methyl ether (5.31%–17.79%), p-methoxyheptanophenone (5.07%–9.65%), and α-isocomene (0.68%–2.87%), were detected in the rhizomes and roots of the three-year-old plants and in the rhizomes and roots of the four-year-old plants. The plant part (rhizome, root) and plant age can be determinants of the essential oil composition and, consequently, their biological activity. The induction of apoptosis (but not autophagy nor necrosis) at a level of 28.5%–32.3% is a promising result, for which 2,5-dimethoxy-p-cymene, 2,6-diisopropylanisole, thymol methyl ether, and p-methoxyheptanophenone are probably mainly responsible. The present study is the first report on the anticancer activities of essential oils from A. montana rhizomes and roots.

Revealing the epigenetic effect of temozolomide on glioblastoma cell lines in therapeutic conditions

Temozolomide (TMZ) is a drug of choice in glioblastoma treatment. Its therapeutic applications expand also beyond high grade gliomas. However, a significant number of recurrences and resistance to the drug is observed. The key factor in each chemotherapy is to achieve the therapeutic doses of a drug at the pathologic site. Nonetheless, the rate of temozolomide penetration from blood to cerebrospinal fluid is only 20–30%, and even smaller into brain intestinum. That makes a challenge for the therapeutic regimens to obtain effective drug concentrations with minimal toxicity and minor side effects. The aim of our research was to explore a novel epigenetic mechanism of temozolomide action in therapeutic conditions. We analyzed the epigenetic effects of TMZ influence on different glioblastoma cell lines in therapeutically achieved TMZ concentrations through total changes of the level of 5-methylcytosine in DNA, the main epigenetic marker. That was done with classical approach of radioactive nucleotide post-labelling and separation on thin-layer chromatography. In the range of therapeutically achieved temozolomide concentrations we observed total DNA hypomethylation. The significant hypermethylating effect was visible after reaching TMZ concentrations of 10–50 μM (depending on the cell line). Longer exposure time promoted DNA hypomethylation. The demethylated state of the glioblastoma cell lines was overcome by repeated TMZ applications, where dose-dependent increase in DNA 5-methylcytosine contents was observed. Those effects were not seen in non-cancerous cell line. The increase of DNA methylation resulting in global gene silencing and consecutive down regulation of gene expression after TMZ treatment may explain better glioblastoma patients’ survival.

Bioactive Phenolic Compounds in the Modulation of Central and Peripheral Nervous System Cancers: Facts and Misdeeds

Efficacious therapies are not available for the cure of both gliomas and glioneuronal tumors, which represent the most numerous and heterogeneous primary cancers of the central nervous system (CNS), and for neoplasms of the peripheral nervous system (PNS), which can be divided into benign tumors, mainly represented by schwannomas and neurofibromas, and malignant tumors of the peripheral nerve sheath (MPNST). Increased cellular oxidative stress and other metabolic aspects have been reported as potential etiologies in the nervous system tumors. Thus polyphenols have been tested as effective natural compounds likely useful for the prevention and therapy of this group of neoplasms, because of their antioxidant and anti-inflammatory activity. However, polyphenols show poor intestinal absorption due to individual intestinal microbiota content, poor bioavailability, and difficulty in passing the blood-brain barrier (BBB). Recently, polymeric nanoparticle-based polyphenol delivery improved their gastrointestinal absorption, their bioavailability, and entry into defined target organs. Herein, we summarize recent findings about the primary polyphenols employed for nervous system tumor prevention and treatment. We describe the limitations of their application in clinical practice and the new strategies aimed at enhancing their bioavailability and targeted delivery.

Diosmin induces caspase-dependent apoptosis in human glioblastoma cells

Diosmin is a flavone glycoside clinically used as the main component of Daflon for the treatment of venous diseases. Several studies demonstrated that this natural compound can induce apoptosis in different tumors. However, isolated diosmin has not been studied regarding its effects on glioblastoma so far. Since glioblastoma is a highly lethal and fast-growing brain tumor, new therapeutic strategies are urgently needed. Herein, we evaluated the role of this flavonoid against glioblastoma cells using in vitro assays. Diosmin significantly reduced the viability of GBM95, GBM02, and U87MG glioblastoma cells, but not of healthy human astrocytes, as verified by MTT assay. Vimentin immunostaining showed that diosmin induced morphological changes in GBM95 and GBM02 cells, making them smaller and more polygonal. Diosmin did not inhibit GBM95 and GBM02 cell proliferation, but it caused DNA fragmentation, as verified by the TUNEL assay, and increased cleaved caspase-3 expression in these cells. In summary, diosmin is able to induce caspase-dependent apoptosis specifically in tumor cells and, therefore, could be considered a promising therapeutic compound against glioblastoma.

Essential Oil from Arnica Montana L. Achenes: Chemical Characteristics and Anticancer Activity

Mountain arnica Arnica montana L. is a source of several metabolite classes with diverse biological activities. The chemical composition of essential oil and its major volatile components in arnica may vary depending on the geographical region, environmental factors, and plant organ. The objective of this study was to characterize the chemical composition of essential oil derived from A. montana achenes and to investigate its effect on induction of apoptosis and autophagy in human anaplastic astrocytoma MOGGCCM and glioblastoma multiforme T98G cell lines. The chemical composition of essential oil extracted from the achenes was examined with the use of Gas Chromatography–Mass Spectrometry GC-MS. Only 16 components of the essential oil obtained from the achenes of 3-year-old plants and 18 components in the essential oil obtained from the achenes of 4-year-old plants constituted ca. 94.14% and 96.38% of the total EO content, respectively. The main components in the EO from the arnica achenes were 2,5-dimethoxy-p-cymene (39.54 and 44.65%), cumene (13.24 and 10.71%), thymol methyl ether (8.66 and 8.63%), 2,6-diisopropylanisole (8.55 and 8.41%), decanal (7.31 and 6.28%), and 1,2,2,3-tetramethylcyclopent-3-enol (4.33 and 2.94%) in the 3- and 4-year-old plants, respectively. The essential oils were found to exert an anticancer effect by induction of cell death in anaplastic astrocytoma and glioblastoma multiforme cells. The induction of apoptosis at a level of 25.7–32.7% facilitates the use of this secondary metabolite in further studies focused on the development of glioma therapy in the future. Probably, this component plays a key role in the anticancer activity against the MOGGCCM and T98G cell lines. The present study is the first report on the composition and anticancer activities of essential oil from A. montana achenes, and further studies are required to explore its potential for future medicinal purposes.

Temozolomide and tranilast synergistic antiproliferative effect on human glioblastoma multiforme cell line (U87MG)

Background: Glioblastoma multiforme (GBM) is the most malignant primary brain tumor. Temozolomide (TMZ) is a chemotherapeutic agent that has been used in GBM treatment. Resistance to TMZ is a major obstacle to successful GBM treatment. The aim of the present study was to investigate the effect of TMZ and tranilast on human GBM cell line (U87MG). Methods: In this in vitro experimental study, the effect of TMZ and tranilast on cell proliferation was measured using the MTT assay. Median effect analysis was performed to determine the TMZ and tranilast interaction. Lactate dehydrogenase assay was used to determine TMZ and tranilast cytotoxicity. Cell fluorescent staining and real-time PCR were used for apoptosis evaluation. The effect of TMZ and tranilast on U87MG nitric oxide (NO) production was evaluated by Griess assay. Results: TMZ and tranilast had a significant dose- and time-dependent inhibitory effect on cell proliferation. The mean combination index values represented a synergistic effect, and dose reduction index values suggested the advantages of reducing the toxicity, adverse effects, and drug resistance in combination of TMZ and tranilast. Apoptosis cell death was induced by TMZ and/or tranilast in cells. TMZ and tranilast reduced NO. production in cells. Conclusion: TMZ and tranilast combination inhibited the GBM cells growth effectively.

Resveratrol and siRNA in combination reduces Hsp27 expression and induces caspase-3 activity in human glioblastoma cells

GBM cells can easily gain resistance to conventional therapy, and therefore treatment of glioblastoma multiforme (GBM) is difficult. One of the hallmark proteins known to be responsible for this resistance is heat shock protein 27 (Hsp27) which has a key role in the cell survival. Resveratrol, a natural compound, exhibits antitumor effects against GBM, but there are no reports regarding its effect on Hsp27 expression in gliomas. The aim of the present study was to asses the effect of resveratrol on Hsp27 expression and apoptosis in non-transfected and transfected U-87 MG human glioblastoma cells. In order to block the Hsp27 expression, siRNA transfection was performed. Non-transfected and transfected cells were treated with either 10 or 15 μM resveratrol. The effects of resveratrol were compared with quercetin, a well-known Hsp27 inhibitor. Resveratrol was found to induce apoptosis more effectively than quercetin. Our data showed that resveratrol induces dose- and time-dependent cell death. We also determined that silencing of Hsp27 with siRNA makes the cells more vulnerable to apoptosis upon resveratrol treatment. The highest effect was observed in the 15 μM resveratrol and 25 nM siRNA combination group (suppressed Hsp27 expression by 93.4% and induced apoptosis by 101.2%). This study is the first report showing that resveratrol reduces Hsp27 levels, and siRNA-mediated Hsp27 silencing enhances the therapeutic effects of resveratrol in glioma cells. Our results suggest that resveratrol administration in combination with Hsp27 silencing has a potential to be used as a candidate for GBM treatment.

Chelidonine Induces Caspase-Dependent and Caspase-Independent Cell Death through G2/M Arrest in the T98G Human Glioblastoma Cell Line

Chelidonium majus L. (family Papaveraceae), commonly known as greater celandine or tetterwort, has been reported to have antibacterial and anticancer effects and chelidonine is known as a functional metabolite extracted from C.

Effect of Turkish Propolis on miRNA Expression, Cell Cycle, and Apoptosis in Human Breast Cancer (MCF-7) Cells

Enriched in flavonoid compounds, phenol acids, and terpene derivatives, propolis has been shown to regulate apoptosis signaling pathways and alter the expression of microRNAs (miRNAs). In the present study, it has been aimed to examine the effects of Turkish propolis on miRNA levels of breast cancer (MCF-7) cells, and its relationship with cell proliferation and apoptosis. Cytotoxic activity of ethanolic propolis extract (EEP) was evaluated using MTT assay. Mechanisms involved in the cytotoxic action of Turkish propolis in MCF-7 cells were investigated with regard to apoptosis and cell cycle using flow cytometry and western blot. Mitochondrial membrane potential (MMP) were evaluated by spectrofluorometric method. miRNA levels were detected by qRT-PCR method. EEP exhibited selective toxicity against MCF-7 cells compared to normal fibroblast cells. EEP increased the cell cycle arrest at the G₁ phase. EEP elevated the apoptotic cell death through increasing pro-apoptotic protein levels (p21, Bax, p53, p53-Ser46, and p53-Ser15), decreasing MMP and altering the expression levels of specific tumor suppressors (miR-34, miR-15a, and miR-16-5p) and oncogenic (miR-21) miRNAs. These data support that Turkish propolis may be evaluated as a potential natural agent for new anticancer drugs in future.

Resveratrol restores sensitivity of glioma cells to temozolamide through inhibiting the activation of Wnt signaling pathway

Malignant gliomas are aggressive primary neoplasms that originate in the glial cells of the brain or the spine with notable resistance to standard treatment options. We carried out the study with the aim to shed light on the sensitization of resveratrol to temozolomide (TMZ) against glioma through the Wnt signaling pathway. Initially, glioma cell lines with strong resistance to TMZ were selected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Then, the glioma cells were subjected to resveratrol, TMZ, Wnt signaling pathway inhibitors, and activators. Cell survival rate and inhibitory concentration at half maximum value were detected by MTT, apoptosis by flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, in vitro proliferation by hanging drop method and β-catenin translocation into nuclei by TOP/FOP-FLASH assay. The expressions of the Wnt signaling pathway-related and apoptosis-related factors were determined by western blot analysis. Nude mice with glioma xenograft were established to detect tumorigenic ability. Glioma cell lines T98G and U138 which were highly resistant to TMZ were selected for subsequent experiments. Resveratrol increased the efficacy of TMZ by restraining cell proliferation, tumor growth, and promoting cell apoptosis in glioma cells. Resveratrol inhibited Wnt2 and β-catenin expressions yet elevated GSK-3β expression. Moreover, the Wnt signaling pathway participates in the sensitivity enhancing of resveratrol to TMZ via regulating O ⁶ -methylguanine-DNA methyltransferase (MGMT) expression. Resveratrol sensitized TMZ-induced glioma cell apoptosis by repressing the activation of the Wnt signaling pathway and downregulating MGMT expression, which may confer new thoughts to the chemotherapy of glioma.

Dependence of HSP27 cellular level on protein kinase CK2 discloses novel therapeutic strategies

BACKGROUND

HSP27 plays a role in various diseases, including neurodegenerative diseases, ischemia, and atherosclerosis. It is particularly important in the regulation of the development, progression and metastasis of cancer as well as cell apoptosis and drug resistance. However, the absence of an ATP binding domain, that is, instead, present in other HSPs such as HSP90 and HSP70, hampers the development of small molecules as inhibitors of HSP27.

METHODS

Knockout cell lines generated by Crispr/Cas9 gene editing tool, specific kinase inhibitors and siRNA transfections were exploited to demonstrate that the expression of HSP27 is dependent on the integrity/activity of protein kinase CK2 holoenzyme. The interaction between these proteins has been confirmed by co-immunoprecipitation, confocal immunofluorescence microscopy, and by density gradient separation of protein complexes. Finally, using a proliferation assay this study demonstrates the potential efficacy of a combinatory therapy of heath shock and CK2 inhibitors in cancer treatment.

RESULTS

Our data demonstrate that CK2 is able to regulate HSP27 turnover by affecting the expression of its ubiquitin ligase SMURF2 (Smad ubiquitination regulatory factor 2). Moreover, for the first time we show an increased sensitivity of CK2-inhibited tumour cells to hyperthermia treatment.

CONCLUSION

Being HSP27 involved in several pathological conditions, including protein conformational diseases (i.e Cystic Fibrosis) and cancer, the need of drugs to modulate its activity is growing and CK2-targeting could represent a new strategy to reduce cellular HSP27 level.

GENERAL SIGNIFICANCE

This study identifies CK2 as a molecular target to control HSP27 cellular expression.

Drug resistance in glioblastoma and cytotoxicity of seaweed compounds, alone and in combination with anticancer drugs: A mini review

BACKGROUND

Glioblastomas (GBM) are one of the most aggressive tumor of the central nervous system with an average life expectancy of only 1-2 years after diagnosis, even with the use of advanced treatments with surgery, radiation, and chemotherapy. There are several anticancer drugs with alkylating properties that have been used in the therapy of malignant gliomas. Temozolomide (TMZ) is one of them, widely used even in combination with ionizing radiation. However, the main disadvantage of using these types of drugs in the treatment of GBM is the development of cancer drug resistance. Research of bioactive compounds with anticancer activity has been heavily explored.

PURPOSE

This review focuses on a carotenoid and a phlorotannin present in seaweed, namely fucoxanthin and phloroglucinol, and their anticancer activity against glioblastoma. The combination of natural compounds with conventional drugs is also discussed.

CONCLUSION

Several natural compounds existing in seaweeds, such as fucoxanthin and phoroglucinol, have shown cytotoxic activity in models in vitro and in vivo, acting through different molecular mechanisms, such as antioxidant, antiproliferative, DNA damage/DNA repair, proapoptotic, antiangiogenic and antimetastic. Within the scope of interactions with conventional drugs, there are evidences that some seaweed compounds could be used to potentiate the action of anticancer drugs. However, their effects and mechanisms of action, alone or in combination with anticancer drugs, namely TMZ, in glioblastoma cell, still few explored and require more attention due to the unquestionable high potential of these marine compounds.

Rosmarinic acid and siRNA combined therapy represses Hsp27 (HSPB1) expression and induces apoptosis in human glioma cells

High expression of Hsp27 in glioma cells has been closely associated with tumor cell proliferation and apoptosis inhibition. The aim of the present study was to asses the effects of rosmarinic acid (RA) on Hsp27 expression and apoptosis in non-transfected and transfected human U-87 MG cells. The effect of rosmarinic acid was compared to quercetin, which is known to be a good Hsp27 inhibitor. In order to block the expression of Hsp27 gene (HSPB1), transfection with specific siRNAs was performed. Western blotting technique was used to assess the Hsp27 expression, and caspase-3 colorimetric activity assay was performed to determine apoptosis induction. According to the results, it was found that RA and quercetin effectively silenced Hsp27 and both agents induced apoptosis by activating the caspase-3 pathway. Eighty and 215 μM RA decreased the level of Hsp27 by 28.8 and 46.7% and induced apoptosis by 30 and 54%, respectively. For the first time, we reported that rosmarinic acid has the ability to trigger caspase-3 induced apoptosis in human glioma cells. As a result of siRNA transfection, the Hsp27 gene was silenced by ~ 50% but did not cause a statistically significant change in caspase-3 activation. It was also observed that apoptosis was induced at a higher level as a result of Hsp27 siRNA and subsequent quercetin or RA treatment. siRNA transfection and 215 μM RA treatment suppressed Hsp27 expression level by 90.5% and increased caspase-3 activity by 58%. Herein, we demonstrated that RA administered with siRNA seems to be a potent combination for glioblastoma therapy.

The effect of quercetin on the electrical properties of model lipid membranes and human glioblastoma cells

Quercetin is a naturally-occurring flavonoid claimed to exert many beneficial health effects. In this report, the influence of quercetin on the surface charge of phosphatidylcholine liposomes and human glioblastoma LN-229 and LN-18 cells was studied using microelectrophoretic mobility measurements. The effect of quercetin on the electrical resistance and capacitance of bilayer lipid membranes was analyzed via electrochemical impedance spectroscopy. The results showed that after flavonoid treatment, the cell lines demonstrated changes in surface charge only in alkaline pH solutions, whereas there were no significant alterations in quercetin-treated vs. control cells in acidic pH solutions. The same tendency was found for liposomal membranes proving that quercetin insertion into membranes is strongly pH-dependent. Capacitance and resistance measurements conducted in acidic electrolyte solutions demonstrated an increase in both electrical parameters, indicating an increased amount of quercetin inserted into the bilayers. Moreover, the cytotoxic effect of quercetin confirms that the flavonoid enters the cells and perturbs the proliferation of LN-229 and LN-18 glioblastoma cell lines. As such, our results indicate that the specific localization of quercetin, membrane-bound or cell-entering, might be crucial for its pharmacological activity. However, further studies are necessary prior to applying these physicochemical measurements as standard methods of evaluating drug activity.

Inhibition of the Proliferation and Invasion of C6 Glioma Cells by Tricin via the Upregulation of Focal-Adhesion-Kinase-Targeting MicroRNA-7

Tricin, a natural flavonoid present in large amounts in rice bran, was investigated for the mechanisms by which it exhibited antiproliferation and anti-invasion in C6 glioma cells. The results indicated that treatment with 5, 10, 25, and 50 μM tricin for 48 h significantly ( p < 0.05) inhibited cell numbers and colony numbers with values of 134.3 ± 5.5, 114.6 ± 2.5, 106.3 ± 3.2, and 57.3 ± 10.2, respectively. Tricin also inhibited C6-cell motility, migration, and invasion. Tricin changed the cytoskeletal organization, reduced matrix-metalloproteinase (MMP) expression, and upregulated E-cadherin. Tricin decreased FAK protein levels and suppressed focal-adhesion-kinase (FAK)-downstream-signal activation. Most importantly, tricin dose-dependently upregulated microRNA-7 (miR-7). Transfection with an miR-7 inhibitor suppressed miR-7 expression, increased FAK expression, and promoted the proliferation and invasion in C6 cells. The data support a novel anticancer mechanism of tricin that involves upregulation of FAK-targeting miR-7 in C6 glioma cells.

Sequence‑dependent effect of sorafenib in combination with natural phenolic compounds on hepatic cancer cells and the possible mechanism of action

Sorafenib (Nexavar, BAY43-9006 or Sora) is the first molecular targeted agent that has exhibited significant therapeutic benefits in advanced hepatocellular carcinoma (HCC). However, not all HCC patients respond well to Sora and novel therapeutic strategies to optimize the efficacy of Sora are urgently required. Plant-based drugs have received increasing attention owing to their excellent chemotherapeutic and chemopreventive activities; they are also well tolerated, non-toxic, easily available and inexpensive. It is well known that certain biologically active natural products act synergistically with synthetic drugs used in clinical applications. The present study aimed to investigate whether a combination therapy with natural phenolic compounds (NPCs), including curcumin (Cur), quercetin (Que), kaempherol (Kmf) and resveratrol (Rsv), would allow a dose reduction of Sora without concomitant loss of its effectiveness. Furthermore, the possible molecular mechanisms of this synergy were assessed. The hepatic cancer cell lines Hep3b and HepG2 were treated with Sora alone or in combination with NPCs in concomitant, sequential, and inverted sequential regimens. Cell proliferation, cell cycle, apoptosis and expression of proteins associated with the cell cycle and apoptosis were investigated. NPCs markedly potentiated the therapeutic efficacy of Sora in a sequence-, type-, NPC dose- and cell line-dependent manner. Concomitant treatment with Sora and Cur [sensitization ratio (SR)=28], Kmf (SR=18) or Que (SR=8) was associated with the highest SRs in Hep3b cells. Rsv markedly potentiated the effect of Sora (SR=17) on Hep3b cells when administered in a reverse sequential manner. By contrast, Rsv and Que did not improve the efficacy of Sora against HepG2 cells, while concomitant treatment with Cur (SR=10) or Kmf (SR=4.01) potentiated the cytotoxicity of Sora. Concomitant treatment with Sora and Cur or Kmf caused S-phase and G2/M phase arrest of liver cancer cells and markedly induced apoptosis compared with mono-treatment with Sora, Cur or Kmf. Concomitant treatment with Sora and Cur reduced the protein levels of cyclins A, B2 and D1, phosphorylated retinoblastoma and B-cell lymphoma (Bcl) extra-large protein. By contrast, Sora and Cur co-treatment increased the protein levels of Bcl-2-associated X protein, cleaved caspase-3 and cleaved caspase-9 in a dose-dependent manner. In conclusion, concomitant treatment with Sora and Cur or Kmf appears to be a potent and promising therapeutic approach that may control hepatic cancer by triggering cell cycle arrest and apoptosis. Additional studies are required to examine the potential of combined treatment with Sora and NPCs in human hepatic cancer and other solid tumor types in vivo.

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.

Apoptotic effects of ε-viniferin in combination with cis-platin in C6 cells

Glioblastoma (GBM) is one of the most common and lethal forms of primary brain tumors in human adults. Treatment options are limited, and in most cases ineffective. Natural products are sources of novel compounds endowed with therapeutic properties in many human diseases like cancer. ε-viniferin is a resveratrol dimer and well known for having antiproliferative and apoptotic effects on cancer cells. Cisplatin is a platinum containing anti-cancer drug. In this study, we aimed to investigate antiproliferative and apoptotic effects of using cis-platin and ε-viniferin alone or in combined treatment of C6 cells. Cell proliferation was detected by WST-1. Mitochondrial membrane potential changes in the cells (ΔΨm) were evaluated using cationic dye JC1. Apoptotic index which is a hallmark of late apoptosis was detected by using Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method and apoptotic alterations were observed by transmission electron microscope (TEM). Activation of caspase-8, -9, -3 in C6 cells at various incubation periods was measured by flow cytometer. Apoptotic index increased at highest level in only combined treatment cells (91.6%) after 48 h incubation. These results were supported by TEM images. Caspase-8 activation in C6 cells increased to a maximum (12.5%) after 6 h by using combined cis-platin/ε-viniferin treatment (13.25/95 μM). Caspase-9 was activated at 44.5% after combined treatment for 24 h. This rate is higher than using cis-platin (14.2%) or ε-viniferin (43.3%) alone. The combined 13.25 μM/cisplatin and 95 μM ε-viniferin treatment caused maximum caspase-3 activation in C6 cells (15.5%) at the end of the 72 h incubation. In conclusion, it was observed that caspase-8, -9, -3 activation which was determined in vitro, trigerred apoptotic mechanism in C6 cells by using low concentrations of combined cis-platin and ε-viniferin.

Function of neuronal nitric oxide synthase enzyme in temozolomide-induced damage of astrocytic tumor cells

Astrocytic tumors, including astrocytomas and glioblastomas, are the most common type of primary brain tumors. Treatment for glioblastomas includes radiotherapy, chemotherapy with temozolomide (TMZ) and surgical ablation. Despite certain therapeutic advances, the survival time of patients is no longer than 12-14 months. Cancer cells overexpress the neuronal isoform of nitric oxide synthase (nNOS). In the present study, it was examined whether the nNOS enzyme serves a role in the damage of astrocytoma (U251MG and U138MG) and glioblastoma (U87MG) cells caused by TMZ. First, TMZ (250 µM) triggered an increase in oxidative stress at 2, 48 and 72 h in the U87MG, U251MG and U138MG cell lines, as revealed by 2',7'-dichlorofluorescin-diacetate assay. The drug also reduced cell viability, as measured by MTT assay. U87MG cells presented a more linear decline in cell viability at time-points 2, 48 and 72 h, compared with the U251MG and U138MG cell lines. The peak of oxidative stress occurred at 48 h. To examine the role of NOS enzymes in the cell damage caused by TMZ, N(ω)-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI) were used. L-NAME increased the cell damage caused by TMZ while reducing the oxidative stress at 48 h. The preferential nNOS inhibitor 7-NI also improved the TMZ effects. It caused a 12.8% decrease in the viability of TMZ-injured cells. Indeed, 7-NI was more effective than L-NAME in restraining the increase in oxidative stress triggered by TMZ. Silencing nNOS with a synthetic small interfering (si)RNA (siRNAnNOShum_4400) increased by 20% the effects of 250 µM of TMZ on cell viability (P<0.05). Hoechst 33342 nuclear staining confirmed that nNOS knock-down enhanced TMZ injury. In conclusion, our data reveal that nNOS enzymes serve a role in the damage produced by TMZ on astrocytoma and glioblastoma cells. RNA interference with nNOS merits further studies in animal models to disclose its potential use in brain tumor anticancer therapy.

Cytotoxic effect of Rosa canina extract on human colon cancer cells through repression of telomerase expression

Rosa canina is a member of the genus Rosa that has long been used for medical objectives. Several studies have reported cytotoxic effects of different Rosa species, but there has been only limited investigation of the cytotoxic effect of R. canina. The purpose of the current study was to examine the potential effect of R. canina extract on cell viability, the cell cycle, apoptosis, and the expression of telomerase in human colon cancer (WiDr) cells. The cytotoxic effect of the extract was determined using MTT assay. The mechanism involved in the cytotoxic effect of the extract was then evaluated in terms of apoptosis and the cell cycle using flow cytometry. Mitochondrial membrane potential (MMP) was investigated using the fluorometric method, and expression levels of telomerase were studied using RT-PCR. R. canina extract exhibited a selective cytotoxic effect on WiDr cells compared with normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. R. canina extract significantly repressed telomerase expressions at treatment times of 48 and 72 h in WiDr cells. Our results suggest that R. canina may have considerable potential for development as a novel natural product-based anticancer agent.

Cerebrospinal fluid and serum IL-8, CCL2, and ICAM-1 concentrations in astrocytic brain tumor patients

BACKGROUND

The aim of the study was the evaluation of serum and CSF concentrations of CCL2, IL-8, and sICAM-1 in patients with astrocytic tumors as compared to a group of non-tumoral patients.

METHODS

Chemokine concentrations were measured using the ELISA method.

RESULTS

Regardless of the parameter tested and the patient group (brain tumor or non-tumoral patients), statistical differences (P < 0.05) were found between concentrations obtained in CSF compared to values obtained in serum for all proteins tested. CSF IL-8 concentrations were significantly elevated in CNS tumor patients as compared to non-tumoral individuals (P = 0.000); serum CCL2 and sICAM-1 concentrations were significantly decreased in CNS tumors in comparison with the comparative group (P = 0.002 and P = 0.026, respectively). Among proteins tested in the serum, a higher area under the ROC curve (AUC) revealed CCL2 compared to sICAM-1 in differentiating subjects with CNS brain tumors from non-tumoral subjects. AUC for CSF IL-8 was higher than for its index (CSF IL-8/serum IL-8).

CONCLUSIONS

For individual biomarkers (IL-8 and CCL2, sICAM-1), measured in CNS brain tumor patients, the appropriate material, respectively CSF or serum, should be chosen and quantitatively tested. Increased cerebrospinal fluid IL-8 with decreased serum CCL2 create a pattern of biomarkers, which may be helpful in the management of CNS astrocytic brain tumors.

Glioma progression through the prism of heat shock protein mediated extracellular matrix remodeling and epithelial to mesenchymal transition

Glial tumor is one of the intrinsic brain tumors with high migratory and infiltrative potential. This essentially contributes to the overall poor prognosis by circumvention of conventional treatment regimen in glioma. The underlying mechanism in gliomagenesis is bestowed by two processes- Extracellular matrix (ECM) Remodeling and Epithelial to mesenchymal transition (EMT). Heat Shock Family of proteins (HSPs), commonly known as "molecular chaperons" are documented to be upregulated in glioma. A positive correlation also exists between elevated expression of HSPs and invasive capacity of glial tumor. HSPs overexpression leads to mutational changes in glioma, which ultimately drive cells towards EMT, ECM modification, malignancy and invasion. Differential expression of HSPs - a factor providing cytoprotection to glioma cells, also contributes towards its radioresistance /chemoresistance. Various evidences also display upregulation of EMT and ECM markers by various heat shock inducing proteins e.g. HSF-1. The aim of this review is to study in detail the role of HSPs in EMT and ECM leading to radioresistance/chemoresistance of glioma cells. The existing treatment regimen for glioma could be enhanced by targeting HSPs through immunotherapy, miRNA and exosome mediated strategies. This could be envisaged by better understanding of molecular mechanisms underlying glial tumorigenesis in relation to EMT and ECM remodeling under HSPs influence. Our review might showcase fresh potential for the development of next generation therapeutics for effective glioma management.

Corilagin Induces High Levels of Apoptosis in the Temozolomide-Resistant T98G Glioma Cell Line

Glioblastoma multiforme (GBM), a malignant tumor of the central nervous system, has a high mortality rate. No curative treatment is presently available, and the most commonly used chemotherapeutic drug, the alkylating agent temozolomide (TMZ), is only able to increase life expectancy and is often associated with drug resistance. Therefore, an urgent need does exist for novel drugs aimed at treating gliomas. In the present study, we obtained three major results using corilagin: (a) demonstrated that it inhibits the growth of U251 glioma cells through activation of the apoptotic pathway; (b) demonstrated that it is also active on TMZ-resistant T98G glioma cells; and (c) demonstrated that when used in combination with TMZ on T98G glioma cells, a higher level of proapototic and antiproliferative effects is observed. Our study indicates that corilagin should be investigated in more detail to determine whether it can be developed as a potential therapeutic agent. In addition, our results suggest that corilagin could be used in combination with low doses of other standard anticancer chemotherapeutic drugs against gliomas (such as TMZ) with the aim of obtaining enhanced anticancer effects.