Inhibition of heat shock protein response enhances PS-341-mediated glioma cell death

Heat shock factor 1 in brain tumors: a link with transient receptor potential channels TRPV1 and TRPA1

Novel data report a "cross-talk" between Heat-Shock Factor 1 (HSF1) and the transient receptor potential vanilloid 1 cation channel (TRPV1) located in the cell membrane, introducing these channels as possible drug targets for the regulation of HSF1 activation. This study aims to investigate the co-expression of TRPV1 and HSF1 in human brain tumors. Additionally, the expression of the transient receptor potential ankyrin 1 channel (TRPA1), which is co-operated with TRPV1 in a plethora of cells, was studied. Immunohistochemical staining for HSF1, TRPV1 and TRPA1 expression was quantitatively analyzed in paraffin-embedded semi-serial tissue sections from 74 gliomas and 71 meningiomas. mRNA levels of HSF1, TRPV1 and TRPA1 were evaluated using real-time PCR. Although HSF1 was significantly increased compared with TRPV1/TRPA1 (p ≤ 0.001) in both gliomas and meningiomas, high co-expression levels for HSF1, TRPV1 and TRPA1 were found in 62.50% of diffuse fibrillary astrocytomas (WHO, grade II), 37.50% of anaplastic astrocytomas (WHO, grade III), 16.32% of glioblastomas multiforme (WHO, grade IV), and 42.25% of meningiomas (WHO, grade I and II). Correlation analysis revealed a relationship of HSF1 with TRPV1/TRPA1 in diffuse fibrillary astrocytomas (WHO, grade II) and benign meningiomas (WHO, grade I) contrary to glioblastomas multiforme (WHO, grade IV) and high grade meningiomas (WHO, grade II). Importantly, TRPA1 and TRPV1 expression levels were significantly increased in meningiomas compared with astrocytic tumors (p < 0.05). In conclusion, HSF1 and TRPV1/TRPA1 co-expression may be implicated in the pathogenesis of human brain tumors and should be considered for the therapeutic approaches for these tumors.

DnaJ homolog subfamily A member1 (DnaJ1) is a newly discovered anti-apoptotic protein regulated by azadirachtin in Sf9 cells

Background

Azadirachtin, one of the most promising botanical insecticides, has been widely used for pest control. Azadirachtin induces apoptosis in insect cell lines, including Sf9, SL-1 and BTI-Tn-5B1–4. Mitochondrial and lysosomal pathways are likely involved in the azadirachtin-induced apoptosis, however, detailed molecular mechanisms remain largely undefined.

Results

Azadirachtin-induced apoptosis in Sf9 cells was verified by morphological observation, Hoechst 33258 staining, and a Caspase-3-based analysis. Comparative two-dimensional gel electrophoresis (2-DE) coupled with a linear ion trap quadrupole (LTQ)-MS/MS analysis identified 12 prominent, differentially expressed proteins following azadirachtin treatment. These differentially expressed genes are involved in regulating cytoskeleton development, signal transduction, gene transcription, and cellular metabolism. Knockdown gene expression of a gene encoding a DnaJ homolog enhanced apoptosis induced by azadirachtin in Sf9 cells.

Conclusion

Azadirachtin treatment induces apoptosis in Sf9 cells and affects expression of multiple genes with functions in cytoskeleton development, signal transduction, gene regulation, and cellular metabolisms. Azadirachtin induces apoptosis at least partially by down-regulation of Sf-DnaJ in Sf9 cells.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4801-z) contains supplementary material, which is available to authorized users.

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.

Stress Response Leading to Resistance in Glioblastoma-The Need for Innovative Radiotherapy (iRT) Concepts

Glioblastoma (GBM) is the most common and most aggressive malignant primary brain tumor in adults. In spite of multimodal therapy concepts, consisting of surgery, radiotherapy and chemotherapy, the median survival, merely 15–18 months, is still poor. Mechanisms for resistance of GBM to radio(chemo)therapy are not fully understood yet and due to the genetic heterogeneity within the tumor including radiation-resistant tumor stem cells, there are several factors leading to therapy failure. Recent research revealed that, hypoxia during radiation and miRNAs may adversely affect the therapeutic response to radiotherapy. Further molecular alterations and prognostic markers like the DNA-repair protein O6-methylguanine-DNA methyltransferase (MGMT), anti-apoptotic molecular chaperones, and/or the activity of aldehyde dehydrogenase 1 (ALDH1) have also been identified to play a role in the sensitivity to cytostatic agents. Latest approaches in the field of radiotherapy to use particle irradiation or dose escalation strategies including modern molecular imaging, however, need further evaluation with regard to long-term outcome. In this review we focus on current information about the mechanisms and markers that mediate resistance to radio(chemo)therapy, and discuss the opportunities of Innovative Radiotherapy (iRT) concepts to improve treatment options for GBM patients.

Effects of temozolomide (TMZ) on the expression and interaction of heat shock proteins (HSPs) and DNA repair proteins in human malignant glioma cells

We previously reported the association of HSPA1A and HSPB1 with high-grade astrocytomas, suggesting that these proteins might be involved in disease outcome and response to treatment. With the aim to better understand the resistance/susceptibility processes associated to temozolomide (TMZ) treatment, the current study was performed in three human malignant glioma cell lines by focusing on several levels: (a) apoptotic index and senescence, (b) DNA damage, and (c) interaction of HSPB1 with players of the DNA damage response. Three human glioma cell lines, Gli36, U87, and DBTRG, were treated with TMZ evaluating cell viability and survival, apoptosis, senescence, and comets (comet assay). The expression of HSPA (HSPA1A and HSPA8), HSPB1, O6-methylguanine-DNA methyltransferase (MGMT), MLH1, and MSH2 was determined by immunocytochemistry, immunofluorescence, and Western blot. Immunoprecipitation was used to analyze protein interaction. The cell lines exhibited differences in viability, apoptosis, and senescence after TMZ administration. We then focused on Gli36 cells (relatively unstudied) which showed very low recovery capacity following TMZ treatment, and this was related to high DNA damage levels; however, the cells maintained their viability. In these cells, MGMT, MSH2, HSPA, and HSPB1 levels increased significantly after TMZ administration. In addition, MSH2 and HSPB1 proteins appeared co-localized by confocal microscopy. This co-localization increased after TMZ treatment, and in immunoprecipitation analysis, MSH2 and HSPB1 appeared interacting. In contrast, HSPB1 did not interact with MGMT. We show in glioma cells the biological effects of TMZ and how this drug affects the expression levels of heat shock proteins (HSPs), MGMT, MSH2, and MLH1. In Gli36 cells, the results suggest that interactions between HSPB1 and MSH2, including co-nuclear localization, may be important in determining cell sensitivity to TMZ.

Effects of HIP in protection of HSP70 for stress-induced cardiomyocytes injury and its glucorticoid receptor pathway

Moderate levels of stress can be beneficial to health, while stress overload can cause injury or contribute to diseases. Despite a number of studies of adaptation or stress damage, the mechanisms of adaptation and stress damage remain far from clear. The effect and mechanisms of adaptation on cardiomyocytes damage caused by stress overload are discussed in this study. Data showed that mild repeated stress mitigated stress overload-induced cardiomyocyte injury both in an animal model of restraint stress and in H9C2 cells with GC (glucocorticoid) treatment. HSP70, HIP expression and interaction between HSP70 and HIP increased during adaptation induced by mild stress both in animals and H9C2 cells. Overexpression or inhibition of HSP70 in H9C2 cells with pCDNA-3.1-Hsp70 or KNK437 (HSP70 inhibitor) showed that HSP70 can protect H9C2 cells from GC-induced cell damage. A luciferase assay showed that Hsp70 plays its protective role through inhibition of GR transcription activity dependent on the interaction with HIP. These results indicated that HSP70 may promote adaptation with its interacting protein HIP, and increased levels of HSP70 and its interacting protein HIP during adaptation may play a protective role on stress-overload-induced cardiomyocyte injury.

Enhanced HSP30 and HSP70 accumulation in Xenopus cells subjected to concurrent sodium arsenite and cadmium chloride stress

Heat shock proteins (HSPs) are molecular chaperones that aid in protein folding, translocation and in preventing stress-induced protein aggregation. The present study examined the effect of simultaneous sodium arsenite and cadmium chloride treatment on the pattern of HSP30 and HSP70 accumulation in A6 kidney epithelial cells of the frog, Xenopus laevis. Immunoblot analysis revealed that HSP30 and HSP70 accumulation in concurrent stressor treatments were significantly higher than the sum of HSP30 or HSP70 accumulation in individual treatments. This finding suggested a synergistic action between sodium arsenite and cadmium chloride. KNK437 inhibitor studies indicated that the combined stressor-induced accumulation of HSPs may be regulated, at least in part, at the level of transcription. Immunocytochemistry revealed that simultaneous treatment of cells with the two stressors induced HSP30 accumulation primarily in the cytoplasm in a punctate pattern with some dysregulation of F-actin structure. Increased ubiquitinated protein accumulation was observed with combined sodium arsenite and cadmium chloride treatment compared to individual stressors suggesting an impairment of the ubiquitin proteasome degradation system. The addition of a mild heat shock further enhanced the accumulation of HSP30 and HSP70 in response to relatively low concentrations of sodium arsenite plus cadmium chloride.

Antitumor activity of dichloroacetate on C6 glioma cell: in vitro and in vivo evaluation

Dichloroacetate (DCA), a small molecule mitochondria-targeting agent, can penetrate the blood-brain barrier, showing potential therapeutic effects on brain tumors. Considering the effects of DCA on tumor cellular metabolism, penetrating across the blood-brain barrier, as well as having potential antitumor activity on brain tumors, the purpose of this study is to investigate the antitumor activity of DCA on C6 glioma cells in vitro and in vivo. DCA inhibited C6 glioma cell proliferation, induced C6 cell apoptosis, and arrested C6 cells in S phase. DCA can inhibit the expression of heat shock proteins 70 (Hsp70) in a dose-dependent and time-dependent manner (P < 0.01). Our in vivo antitumor effect results indicated that DCA markedly inhibited the growth of C6 glioma tumors in both C6 brain tumor-bearing rats and C6 tumor-bearing nude mice (P < 0.01). DCA significantly induced the ROS production and decreased the mitochondrial membrane potential in tumor tissues. Our in vivo antitumor effect results also indicated that DCA has potential antiangiogenic effects. In conclusion, DCA may be a viable therapeutic agent in the treatment of gliomas.