Expression and function of ABCG2 and XIAP in glioblastomas

Therapeutic approaches to modulate the immune microenvironment in gliomas

Immunomodulatory therapies, including immune checkpoint inhibitors, have drastically changed outcomes for certain cancer types over the last decade. Gliomas are among the cancers that have seem limited benefit from these agents, with most trials yielding negative results. The unique composition of the glioma immune microenvironment is among the culprits for this lack of efficacy. In recent years, several efforts have been made to improve understanding of the glioma immune microenvironment, aiming to pave the way for novel therapeutic interventions. In this review, we discuss some of the main components of the glioma immune microenvironment, including macrophages, myeloid-derived suppressor cells, neutrophils and microglial cells, as well as lymphocytes. We then provide a comprehensive overview of novel immunomodulatory agents that are currently in clinical development, namely oncolytic viruses, vaccines, cell-based therapies such as CAR-T cells and CAR-NK cells as well as antibodies and peptides.

ABCG2 Gene Expression in Non-Small Cell Lung Cancer

Background/Objectives: ATP-binding cassette subfamily G member 2 [ABCG2/breast cancer resistance protein (BCRP)] contributes to mechanisms of multidrug resistance (MDR) and is a marker of side population (SP) cells in human cancers. The primary objective of this study was to investigate the impact of ABCG2 gene expression on the non-small cell lung cancer (NSCLC) development, course of cancer disease, and patient prognosis using publicly available data. Obtained results were supplemented with assessment of ABCG2 expression in blood of NSCLC patients. Methods: The dataset of lung cancer was analyzed utilizing the TIMER 2.0, UALCAN, TNMplot, MEXPRESS, cBioPortal, MethSurv, KM Plotter, STRING, and ShinyGO 0.80 databases. Blood samples from 50 patients were assessed using the real-time PCR method. Results: The ABCG2 gene was expressed at a low level in NSCLC, and did not correlate with clinical aggressiveness of lung cancer. Higher ABCG2 expression improved overall survival, but only in LUAD. In addition, CpG sites located on the CpG island affecting the NSCLC patient's prognosis were indicated. In the case of our own laboratory results, the study did not reveal any changes in the ABCG2 expression levels in blood collected from patients at different time points during the diagnostic-therapeutic procedure. In the in silico analysis, most ABCG2 protein interactors were associated with the development of drug resistance. Conclusions: ABCG2 appears to have a particularly significant impact on the survival of patients with lung cancer and on the effect of immunotherapy related to immune cell infiltration. Presented findings may support personalized medicine strategies based on bioinformatics findings.

ABCG2 shields against epilepsy, relieves oxidative stress and apoptosis via inhibiting the ISGylation of STAT1 and mTOR

The transporter protein ABC subfamily G member 2 (ABCG2) is implicated in epilepsy; however, its specific role remains unclear. In this study, we assessed changes in ABCG2 expression and its role in epilepsy both in vitro and in vivo. We observed an instantaneous increase in ABCG2 expression in epileptic animals and cells. Further, ABCG2 overexpression significantly suppressed the oxidative stress and apoptosis induced by glutamate, kainic acid (KA), and lipopolysaccharide (LPS) in neuronal and microglia cells. Furthermore, inhibiting ABCG2 activity offset this protective effect. ABCG2-deficient mice (ABCG2-/-) showed shorter survival times and decreased survival rates when administered with pentylenetetrazole (PTZ). We also noticed the accumulation of signal transducer and activator of transcription 1 (STAT1) and decreased phosphorylation of mammalian target of rapamycin kinase (mTOR) along with increased ISGylation in ABCG2-/- mice. ABCG2 overexpression directly interacted with STAT1 and mTOR, leading to a decrease in their ISGylation. Our findings indicate the rapid increase in ABCG2 expression acts as a shield in epileptogenesis, indicating ABCG2 may serve as a potential therapeutic target for epilepsy treatment.

The impact of ATP-binding cassette transporters in the diseased brain: Context matters

ATP-binding cassette (ABC) transporters facilitate the movement of diverse molecules across cellular membranes, including those within the CNS. While most extensively studied in microvascular endothelial cells forming the blood-brain barrier (BBB), other CNS cell types also express these transporters. Importantly, disruptions in the CNS microenvironment during disease can alter transporter expression and function. Through this comprehensive review, we explore the modulation of ABC transporters in various brain pathologies and the context-dependent consequences of these changes. For instance, downregulation of ABCB1 may exacerbate amyloid beta plaque deposition in Alzheimer's disease and facilitate neurotoxic compound entry in Parkinson's disease. Upregulation may worsen neuroinflammation by aiding chemokine-mediated CD8 T cell influx into multiple sclerosis lesions. Overall, ABC transporters at the BBB hinder drug entry, presenting challenges for effective pharmacotherapy. Understanding the context-dependent changes in ABC transporter expression and function is crucial for elucidating the etiology and developing treatments for brain diseases.

Molecular signature of stem-like glioma cells (SLGCs) from human glioblastoma and gliosarcoma

Glioblastoma multiforme (GBM) and the GBM variant gliosarcoma (GS) are among the tumors with the highest morbidity and mortality, providing only palliation. Stem-like glioma cells (SLGCs) are involved in tumor initiation, progression, therapy resistance, and relapse. The identification of general features of SLGCs could contribute to the development of more efficient therapies. Commercially available protein arrays were used to determine the cell surface signature of eight SLGC lines from GBMs, one SLGC line obtained from a xenotransplanted GBM-derived SLGC line, and three SLGC lines from GSs. By means of non-negative matrix factorization expression metaprofiles were calculated. Using the cophenetic correlation coefficient (CCC) five metaprofiles (MPs) were identified, which are characterized by specific combinations of 7-12 factors. Furthermore, the expression of several factors, that are associated with GBM prognosis, GBM subtypes, SLGC differentiation stages, or neural identity was evaluated. The investigation encompassed 24 distinct SLGC lines, four of which were derived from xenotransplanted SLGCs, and included the SLGC lines characterized by the metaprofiles. It turned out that all SLGC lines expressed the epidermal growth factor EGFR and EGFR ligands, often in the presence of additional receptor tyrosine kinases. Moreover, all SLGC lines displayed a neural signature and the IDH1 wildtype, but differed in their p53 and PTEN status. Pearson Correlation analysis identified a positive association between the pluripotency factor Sox2 and the expression of FABP7, Musashi, CD133, GFAP, but not with MGMT or Hif1α. Spherical growth, however, was positively correlated with high levels of Hif1α, CDK4, PTEN, and PDGFRβ, whereas correlations with stemness factors or MGMT (MGMT expression and promoter methylation) were low or missing. Factors highly expressed by all SLGC lines, irrespective of their degree of stemness and growth behavior, are Cathepsin-D, CD99, EMMPRIN/CD147, Intβ1, the Galectins 3 and 3b, and N-Cadherin.

[Patients with long-term survival in malignant gliomas after photodynamic therapy]

OBJECTIVE

Analysis of long-lived patients from the group of patients with glioblastomas after using photodynamic therapy in the structure of their complex treatment in order to assess the influence of various factors on their life expectancy.

MATERIAL AND METHODS

In total, a single-center, retrospective categorical study analyzed the long-term results of treatment of 63 patients with glioblastoma in the structure of complex treatment including photodynamic therapy. Clinical factors (age, sex, number of cases, preoperative Karnofsky index, location and size of the tumor, radicality of the operation), histological (nuclear polymorphism, mitosis, vascular proliferation, necrosis), immunohistochemical (Ki-67, p53 index) molecular-genetic factors (expression of VEGF, MGMT, IDH, CD34), amount of radiation and chemotherapy were analyzed.

RESULTS

In the entire group of patients, there was a direct correlation of life expectancy with MGMT status, IDH status, the number of courses of chemotherapy, the age of the patient, and the severity of the first surgical intervention.

CONCLUSION

Clinical features such as age at diagnosis and extent of surgical resection and amount of chemotherapy have predictive value in assessing their effect on life expectancy. Mutations in IDH and MGMT promoter methylation were the most important molecular factors determining long-term patient survival.

Cancer Stem Cell and Aggressiveness Traits Are Promoted by Stable Endothelin-Converting Enzyme-1c in Glioblastoma Cells

Glioblastoma (GBM) is the most common and aggressive type of brain tumor due to its elevated recurrence following treatments. This is mainly mediated by a subpopulation of cells with stemness traits termed glioblastoma stem-like cells (GSCs), which are extremely resistant to anti-neoplastic drugs. Thus, an advancement in the understanding of the molecular processes underlying GSC occurrence should contribute significantly towards progress in reducing aggressiveness. High levels of endothelin-converting enzyme-1 (ECE1), key for endothelin-1 (ET-1) peptide activation, have been linked to the malignant progression of GBM. There are four known isoforms of ECE1 that activate ET-1, which only differ in their cytoplasmic N-terminal sequences. Isoform ECE1c is phosphorylated at Ser-18 and Ser-20 by protein kinase CK2, which increases its stability and hence promotes aggressiveness traits in colon cancer cells. In order to study whether ECE1c exerts a malignant effect in GBM, we designed an ECE1c mutant by switching a putative ubiquitination lysine proximal to the phospho-serines Lys-6-to-Arg (i.e., K6R). This ECE1c^K6R mutant was stably expressed in U87MG, T98G, and U251 GBM cells, and their behavior was compared to either mock or wild-type ECE1c-expressing clone cells. ECE1c^K6R behaved as a highly stable protein in all cell lines, and its expression promoted self-renewal and the enrichment of a stem-like population characterized by enhanced neurospheroid formation, as well as increased expression of stem-like surface markers. These ECE1c^K6R-derived GSC-like cells also displayed enhanced resistance to the GBM-related chemotherapy drugs temozolomide and gemcitabine and increased expression of the ABCG2 efflux pump. In addition, ECE1c^K6R cells displayed enhanced metastasis-associated traits, such as the modulation of adhesion and the enhancement of cell migration and invasion. In conclusion, the acquisition of a GSC-like phenotype, together with heightened chemoresistance and invasiveness traits, allows us to suggest phospho-ECE1c as a novel marker for poor prognosis as well as a potential therapeutic target for GBM.

The dual role of the CD95 and CD95L signaling pathway in glioblastoma

Binding of CD95, a cell surface death receptor, to its homologous ligand CD95L, transduces a cascade of downstream signals leading to apoptosis crucial for immune homeostasis and immune surveillance. Although CD95 and CD95L binding classically induces programmed cell death, most tumor cells show resistance to CD95L-induced apoptosis. In some cancers, such as glioblastoma, CD95-CD95L binding can exhibit paradoxical functions that promote tumor growth by inducing inflammation, regulating immune cell homeostasis, and/or promoting cell survival, proliferation, migration, and maintenance of the stemness of cancer cells. In this review, potential mechanisms such as the expression of apoptotic inhibitor proteins, decreased activity of downstream elements, production of nonapoptotic soluble CD95L, and non-apoptotic signals that replace apoptotic signals in cancer cells are summarized. CD95L is also expressed by other types of cells, such as endothelial cells, polymorphonuclear myeloid-derived suppressor cells, cancer-associated fibroblasts, and tumor-associated microglia, and macrophages, which are educated by the tumor microenvironment and can induce apoptosis of tumor-infiltrating lymphocytes, which recognize and kill cancer cells. The dual role of the CD95-CD95L system makes targeted therapy strategies against CD95 or CD95L in glioblastoma difficult and controversial. In this review, we also discuss the current status and perspective of clinical trials on glioblastoma based on the CD95-CD95L signaling pathway.

USP7 targets XIAP for cancer progression: Establishment of a p53-independent therapeutic avenue for glioma

Ubiquitin specific peptidase 7 (USP7) is a deubiquitinating enzyme (DUB) that removes ubiquitin tags from specific target protein substrates in order to alter their degradation rate, sub-cellular localization, interaction, and activity. The induction of apoptosis upon USP7 inhibition is well established in cancer containing wild type p53, which operates through the 'USP7-Mdm2-p53' axis. However, in cancers without functional p53, USP7-dependent apoptosis is induced through many other alternative pathways. Here, we have identified another critical p53 independent path active under USP7 to regulate apoptosis. Proteomics analysis identifies XIAP as a potential target of USP7-dependent deubiquitination. GSEA analysis revealed up-regulation of apoptosis signalling upon USP7 inhibition associated with XIAP down-regulation. Modulation of USP7 expression and activity in multiple cancer cell lines showed that USP7 deubiquitinates XIAP to inhibit apoptosis in a caspase-dependent pathway, and the combinatorial inhibition of USP7 and XIAP induces apoptosis in vitro and in vivo. Immunohistochemical staining revealed that grade-wise accumulation of USP7 correlated with an elevated level of XIAP in glioma tissue. This is the first report on the identification and validation of XIAP as a novel substrate of USP7 and together, they involve in the empowerment of the tumorigenic potential of cancer cells by inhibiting apoptosis.

Differences of macrophages in the tumor microenvironment as an underlying key factor in glioma patients

BACKGROUND

Macrophages, the major immune cells in glioma microenvironment, are closely related to tumor prognosis. Further studies are needed to investigate macrophages, which will be helpful to fully understand the role of it and early achieve clinical translation.

METHODS

A total of 1334 glioma cases were enrolled in this study from 3 databases. In our works, the single cell cohorts from GSE89567, GSE84465, and the Chinese Glioma Genome Atlas (CGGA) datasets were used to analyze the key genes of macrophage. The bulk sequencing data from the Cancer Genome Atlas (TCGA) and CGGA datasets were respectively divided into the training set and validation set to test prognostic value of the key genes from single cell analysis.

RESULTS

Quantitative and functional differences significantly emerge in macrophage clusters between LGG and GBM. Firstly, we used the Seurat R package to identify 281 genes differentially expressed genes in macrophage clusters between LGG and GBM. Furthermore, based on these genes, we developed a predictive risk model to predict prognosis and reflect the immune microenvironment in glioma. The risk score calculation formula was yielded as follows: Risk score = (0.11 × EXPMACC1) + (-0.31 × EXPOTUD1) + (-0.09 × EXPTCHH) + (0.26 × EXPADPRH) + (-0.40× EXPABCG2) + (0.21 × EXPPLBD1) + (0.12 × EXPANG) + (0.29 × EXPQPCT). The risk score was independently related to prognosis. Further, significant differences existed in immunological characteristics between the low- and high-risk score groups. What is more, mutation analysis found different genomic patterns associated with the risk score.

CONCLUSION

This study further confirms that the proportion of macrophage infiltration is not only significantly different, but the function of them is also different. The signature, identified from the differentially expressed macrophage-related genes impacts poor prognosis and short overall survival and may act as therapeutic targets in the future.

Inhibition of ABCG2 transporter by lapatinib enhances 5-aminolevulinic acid-mediated protoporphyrin IX fluorescence and photodynamic therapy response in human glioma cell lines

5-Aminolevulinic acid (ALA) is an intraoperative molecular probe approved for fluorescence-guided resection (FGR) of high-grade gliomas to achieve maximal safe tumor resection. Although ALA has no fluorescence on its own, it is metabolized in the heme biosynthesis pathway to produce protoporphyrin IX (PpIX) with red fluorescence for tumor detection and photosensitizing activity for photodynamic therapy (PDT). The preferential tumor accumulation of PpIX following ALA administration enables the use of ALA as a prodrug for PpIX FGR and PDT of gliomas. Since intracellular PpIX in tumor cells after ALA treatment is influenced by biological processes including PpIX bioconversion catalyzed by ferrochelatase (FECH) and PpIX efflux by ATP-binding cassette subfamily G member 2 (ABCG2), we determined the activity of FECH and ABCG2 in a panel of human glioma cell lines and correlated with intracellular and extracellular PpIX levels and PDT response. We found that glioma cell lines with ABCG2 activity exhibited the trend of low intracellular PpIX, high extracellular PpIX and low PDT response, whereas no particular correlation was seen with FECH activity. Inhibition of PpIX efflux with ABCG2 inhibitors was more effective in enhancing ALA-PpIX fluorescence and PDT response than blocking PpIX bioconversion with iron chelator deferoxamine. We also showed that a clinically used kinase inhibitor lapatinib could be repurposed for therapeutic enhancement of ALA due to its potent ABCG2 inhibitory activity. Our study reveals ABCG2 as an important biological determinant of PpIX fluorescence in glioma cells and suggests ABCG2 inhibition with lapatinib as a promising therapeutic enhancement approach.

6 ′ -O-Galloylpaeoniflorin Exerts Inhibitory Bioactivities in Human Neuroblastoma Cells via Modulating AMPK/miR-489/XIAP Pathway

Although therapies against neuroblastoma (NBM) have advanced, the patients still suffer from poor prognoses due to distal metastasis or the occurrence of multidrug resistance. Accumulating evidence has proved that chemicals derived from natural products possess potent anti-NBM properties or can be used as adjuvants for chemotherapy. In the present study, we demonstrated that 6′-O-galloylpaeoniflorin (GPF), a galloylated derivative of paeoniflorin isolated from the roots of Paeonia lactiflora Pall, exerted significant inhibitory effects on proliferation and invasion of SH-SY5Y cells (an NBM cell line) and enhanced the sensitivity of SH-SY5Y cells to cisplatin in vitro. Further studies showed that GPF treatment upregulated miR-489 in NBM cells via activating AMP-activated protein kinase (AMPK). We also demonstrated that similar to GPF treatment, miR-489 exhibited a significant anti-NBM capacity. Further studies showed that miR-489 directly targeted the X-linked inhibitor of apoptosis protein (XIAP). Overall, our results indicated that GPF possessed an evident anti-NBM capacity dependent on AMPK/miR-489/XIAP pathway, providing an emerging strategy for clinical treatment of NBM.

[Effects of Extracellular Vesicles on the Drug Resistance of Lung Adenocarcinoma Cells by Modulating the ATP Binding Cassette Transporter G2]

Objective

To investigate the regulatory role of extracellular vesicles (EVs) carrying ATP binding cassette transporter G2 (ABCG2) on the drug resistance of lung adenocarcinoma cells and the relevant molecular mechanisms.

Methods

A549 cells, human lung adenocarcinoma cells, were used to form cisplatin (or cis-Diaminedichloroplatinum, CDDP)-resistant lung adenocarcinoma cells, i.e., A549/CDDP cells. EVs from A549 and A549/CDDP cells were extracted by gradient centrifugation method and were hence named EVs 1 and EVs 2, respectively. The A549 cells were treated with EVs 1 and EVs 2 for 48 hours, and the cells were named A549-EVs 1 and A549-EVs 2 cells, respectively. A549/ ABCG2 cells were established by transfecting A549 cells with pCDNA3.1- ABCG2 recombinant plasmids. On the other hand, A549 cells transfected with empty vectors were named A549/pCDNA3.1 cells. MTT assay was conducted to calculate the 24-hour cell drug resistance index for CDDP. The ABCG2 gene expression in cells and EVs were assessed with real-time PCR. A549 and A549-EVs 2 cells were transplanted subcutaneously into nude mice, which were labeled the control group and the experimental group accordingly. After tumor formation, 3 mg/kg CDDP was intraperitoneally injected once a week for two times. The ABCG2 gene expression of subcutaneous transplanted tumor cells was examined by real-time PCR. The cell apoptosis rate of subcutaneous transplanted tumor cells was examined by flow cytometry.

Results

Using the parental A549 cells as reference, the 24-h CDDP-resistance indexes of 549/CDDP, A549/ ABCG 2, A549/pCDNA3.1, A549-EVs 1, A549-EVs 2 cells were 7.17, 10.06, 1.02, 1.19 and 5.40, respectively. When comparing the ABCG2 gene expression levels in all cells and EVs, the findings were higher in A549/CDDP cells than those inA549 cells, higher in A549/ ABCG2 cells than those in A549/pCDNA3.1 or A549 cells, higher in EVs 2 than those in EVs 1, and higher in A549-EVs 2 than those in A549-EVs 1 cells ( P<0.01) . The volume of transplanted tumor and the ABCG2 gene expression level in the experimental group were higher than those in the control group, while the apoptosis rate was lower than that in the control group ( P<0.01).

Conclusion

EVs carrying ABCG2 gene can regulate the drug resistance of lung adenocarcinoma cells.

Bisdemethoxycurcumin Induces Cell Apoptosis and Inhibits Human Brain Glioblastoma GBM 8401/Luc2 Cell Xenograft Tumor in Subcutaneous Nude Mice In Vivo

Bisdemethoxycurcumin (BDMC) has biological activities, including anticancer effects in vitro; however, its anticancer effects in human glioblastoma (GBM) cells have not been examined yet. This study aimed to evaluate the tumor inhibitory effect and molecular mechanism of BDMC on human GBM 8401/luc2 cells in vitro and in vivo. In vitro studies have shown that BDMC significantly reduced cell viability and induced cell apoptosis in GBM 8401/luc2 cells. Furthermore, BDMC induced apoptosis via inhibited Bcl-2 (anti-apoptotic protein) and increased Bax (pro-apoptotic proteins) and cytochrome c release in GBM 8401/luc2 cells in vitro. Then, twelve BALB/c-nude mice were xenografted with human glioblastoma GBM 8401/luc2 cancer cells subcutaneously, and the xenograft nude mice were treated without and with BDMC (30 and 60 mg/kg of BDMC treatment) every 3 days. GBM 8401/luc2 cell xenografts experiment showed that the growth of the tumors was significantly suppressed by BDMC administration at both doses based on the reduction of tumor size and weights. BDMC did not change the body weight and the H&E histopathology analysis of liver samples, indicating that BDMC did not induce systemic toxicity. Meanwhile, treatment with BDMC up-regulated the expressions of BAX and cleaved caspase-3, while it down-regulated the protein expressions of Bcl-2 and XIAP in the tumor tissues compared with the control group. This study has demonstrated that BDMC presents potent anticancer activity on the human glioblastoma GBM 8401/luc2 cell xenograft model by inducing apoptosis and inhibiting tumor cell proliferation and shows the potential for further development to the anti-GBM cancer drug.

Blockade of Nuclear Factor-Κb (NF-Κb) Pathway Using Bay 11-7082 Enhances Arsenic Trioxide-Induced Antiproliferative Activity in U87 Glioblastoma Cells

BACKGROUND

Glioblastoma (GBM), the most aggressive and common form of glioma, accounts for over 13,000 death per year in the United States which indicates the importance of developing novel strategies for the treatment of this fatal malignancy. Although Arsenic trioxide (ATO) hinders the growth and survival of GBM cells, the requirement of concentrations higher than 4 µM for triggering apoptotic cell death has questioned its safety profile. Since the NF-κB signaling pathway plays a crucial role in tumorigenesis and chemo-resistance, targeting this oncogenic pathway may sensitize GBM cells to lower concentrations of ATO.

METHODS

Anti-tumor effects of ATO as monotherapy and in combination with Bay 11-7082 were determined using MTT, crystal violet staining, Annexin V/PI staining and scratch assays. Quantitative reverse transcription-PCR (qRT-PCR) analysis was applied to elucidate the molecular mechanisms underlying the anti-tumor activity of this combination therapy.

RESULTS

Our results revealed that ATO and Bay 11-7082 synergistically inhibited the proliferation and survival of GBM cells. Also, it was revealed that NF-κB inhibition using Bay 11-7082 enhanced the inhibitory effects of ATO on migration of GBM cells via suppressing the expression of NF-κB target genes such as TWIST, MMP2, ICAM-1, and cathepsin B. Furthermore, combination treatment of GBM cells with ATO and Bay 11-7082 significantly induce apoptotic cell death coupled with downregulation of NF-κB anti-apoptotic target genes including Bcl-2 and IAP family members.

CONCLUSION

Altogether, these findings suggest that combination therapy with ATO and Bay 11-7082 may be a promising strategy for the treatment of GBM.

Pleiotropic Outcomes of Glyphosate Exposure: From Organ Damage to Effects on Inflammation, Cancer, Reproduction and Development

Glyphosate is widely used worldwide as a potent herbicide. Due to its ubiquitous use, it is detectable in air, water and foodstuffs and can accumulate in human biological fluids and tissues representing a severe human health risk. In plants, glyphosate acts as an inhibitor of the shikimate pathway, which is absent in vertebrates. Due to this, international scientific authorities have long-considered glyphosate as a compound that has no or weak toxicity in humans. However, increasing evidence has highlighted the toxicity of glyphosate and its formulations in animals and human cells and tissues. Thus, despite the extension of the authorization of the use of glyphosate in Europe until 2022, several countries have begun to take precautionary measures to reduce its diffusion. Glyphosate has been detected in urine, blood and maternal milk and has been found to induce the generation of reactive oxygen species (ROS) and several cytotoxic and genotoxic effects in vitro and in animal models directly or indirectly through its metabolite, aminomethylphosphonic acid (AMPA). This review aims to summarize the more relevant findings on the biological effects and underlying molecular mechanisms of glyphosate, with a particular focus on glyphosate's potential to induce inflammation, DNA damage and alterations in gene expression profiles as well as adverse effects on reproduction and development.

RNA editing affects cis-regulatory elements and predicts adverse cancer survival

BACKGROUND

RNA editing exerts critical impacts on numerous biological processes and thus are implicated in crucial human phenotypes, including tumorigenesis and prognosis. While previous studies have analyzed aggregate RNA editing activity at the sample level and associated it with overall cancer survival, there is not yet a large-scale disease-specific survival study to examine genome-wide RNA editing sites' prognostic value taking into account the host gene expression and clinical variables.

METHODS

In this study, we solved comprehensive Cox proportional models of disease-specific survival on individual RNA-editing sites plus host gene expression and critical demographic covariates. This allowed us to interrogate the prognostic value of a large number of RNA-editing sites at single-nucleotide resolution.

RESULTS

As a result, we identified 402 gene-proximal RNA-editing sites that generally predict adverse cancer survival. For example, an RNA-editing site residing in ZNF264 indicates poor survival of uterine corpus endometrial carcinoma, with a hazard ratio of 2.13 and an adjusted p-value of 4.07 × 10-7 . Some of these prognostic RNA-editing sites mediate the binding of RNA binding proteins and microRNAs, thus propagating their impacts to extensive regulatory targets.

CONCLUSIONS

In conclusion, RNA editing affects cis-regulatory elements and predicts adverse cancer survival.

Therapeutic Perspective of Temozolomide Resistance in Glioblastoma Treatment

Glioblastoma (GB) is the most lethal form of primary brain neoplasm. TMZ is the first-line standard treatment, but the strong resistance constrains the efficacy in clinical use. GB contains glioma stem cells (GSCs), which contribute to TMZ resistance, promote cell survival evolvement, and repopulate the tumor mass. This review summarizes the TMZ-resistance mechanisms and discusses several potential therapies from the conservative opinion of GSC-targeted therapy orientation to the current view of TMZ resistance-aimed efficacy, which will provide an understanding of the role of heterogeneity in drug resistance and improve therapeutic efficacy in general.

Role of ATP-Binding Cassette Transporter Proteins in CNS Tumors: Resistance- Based Perspectives and Clinical Updates

Despite gigantic advances in medical research and development, chemotherapeutic resistance remains a major challenge in complete remission of CNS tumors. The failure of complete eradication of CNS tumors has been correlated with the existence of several factors including overexpression of transporter proteins. To date, 49 ABC-transporter proteins (ABC-TPs) have been reported in humans, and the evidence of their strong association with chemotherapeutics' influx, dissemination, and efflux in CNS tumors, is growing. Research studies on CNS tumors are implicating ABC-TPs as diagnostic, prognostic and therapeutic biomarkers that may be utilised in preclinical and clinical studies. With the current advancements in cell biology, molecular analysis of genomic and transcriptomic interplay, and protein homology-based drug-transporters interaction, our research approaches are streamlining the roles of ABC-TPs in cancer and multidrug resistance. Potential inhibitors of ABC-TP for better clinical outcomes in CNS tumors have emerged. Elacridar has shown to enhance the chemo-sensitivity of Dasatanib and Imatinib in various glioma models. Tariquidar has improved the effectiveness of Temozolomide's in CNS tumors. Although these inhibitors have been effective in preclinical settings, their clinical outcomes have not been as significant in clinical trials. Thus, to have a better understanding of the molecular evaluations of ABC-TPs, as well as drug-interactions, further research is being pursued in research labs. Our lab aims to better comprehend the biological mechanisms involved in drug resistance and to explore novel strategies to increase the clinical effectiveness of anticancer chemotherapeutics, which will ultimately improve clinical outcomes.

Glioma-Derived miRNA-Containing Extracellular Vesicles Induce Angiogenesis by Reprogramming Brain Endothelial Cells

Glioblastoma (GBM) is characterized by aberrant vascularization and a complex tumor microenvironment. The failure of anti-angiogenic therapies suggests pathways of GBM neovascularization, possibly attributable to glioblastoma stem cells (GSCs) and their interplay with the tumor microenvironment. It has been established that GSC-derived extracellular vesicles (GSC-EVs) and their cargoes are proangiogenic in vitro. To further elucidate EV-mediated mechanisms of neovascularization in vitro, we perform RNA-seq and DNA methylation profiling of human brain endothelial cells exposed to GSC-EVs. To correlate these results to tumors in vivo, we perform histoepigenetic analysis of GBM molecular profiles in the TCGA collection. Remarkably, GSC-EVs and normal vascular growth factors stimulate highly distinct gene regulatory responses that converge on angiogenesis. The response to GSC-EVs shows a footprint of post-transcriptional gene silencing by EV-derived miRNAs. Our results provide insights into targetable angiogenesis pathways in GBM and miRNA candidates for liquid biopsy biomarkers.

ATP-binding cassette transporters restrict drug delivery and efficacy against brain tumors even when blood-brain barrier integrity is lost

The impact of a compromised blood-brain barrier (BBB) on the drug treatment of intracranial tumors remains controversial. We characterize the BBB integrity in several intracranial tumor models using magnetic resonance imaging, fluorescent dyes, and autoradiography and determine the distribution and efficacy of docetaxel in brain tumors grafted in Abcb1-proficient and Abcb1-deficient mice. Leakiness of the tumor vasculature varies from extensive to absent. Regardless of the extent of leakiness, tumor blood vessels express ATP-binding cassette transporters (Abcb1 and Abcg2). A leaky vasculature results in higher docetaxel tumor levels compared to normal brain. Nevertheless, Abcb1 can reduce drug distribution and efficacy even in leaky models. Thus, BBB leakiness does not ensure the unimpeded access of ATP-binding cassette transporter substrate drugs. Therapeutic responses may be observed, but the full potential of such therapeutics may still be attenuated. Consequently, BBB-penetrable drugs with little to no affinity for efflux transporters are preferred for the treatment of intracranial tumors.

Blood-brain barrier integrity in brain tumor models varies from intact to absent

Brain tumor vessels express drug efflux transporters

Drug transporters can impede drug entry and efficacy, even in leaky tumors

Low-affinity ABC transporter drugs are favored candidates for treating brain tumors

Repurposing FDA approved drugs inhibiting mitochondrial function for targeting glioma-stem like cells

Glioblastoma Multiforme (GBM) tumors contain a small population of glioma stem-like cells (GSCs) among the various differentiated GBM cells (d-GCs). GSCs drive tumor recurrence, and resistance to Temozolomide (TMZ), the standard of care (SoC) for GBM chemotherapy. In order to investigate a potential link between GSC specific mitochondria function and SoC resistance, two patient-derived GSC lines were evaluated for differences in their mitochondrial metabolism. In both the lines, GSCs had significantly lower mitochondrial -content, and -function compared to d-GCs. In vitro, the standard mitochondrial-specific inhibitors oligomycin A, antimycin A, and rotenone selectively inhibited GSC proliferation to a greater extent than d-GCs and human primary astrocytes. These findings indicate that mitochondrial inhibition can be a potential GSC-targeted therapeutic strategy in GBM with minimal off-target toxicity. Mechanistically the standard mitochondrial inhibitors elicit their GSC-selective cytotoxic effects through the induction of apoptosis or autophagy pathways. We tested for GSC proliferation in the presence of 3 safe FDA-approved drugs--trifluoperazine, mitoxantrone, and pyrvinium pamoate, all of which are also known mitochondrial-targeting agents. The SoC GBM therapeutic TMZ did not trigger cytotoxicity in glioma stem cells, even at 100 μM concentration. By contrast, trifluoperazine, mitoxantrone, and pyrvinium pamoate exerted antiproliferative effects in GSCs about 30-50 fold more effectively than temozolomide. Thus, we hereby demonstrate that FDA-approved mitochondrial inhibitors induce GSC-selective cytotoxicity, and targeting mitochondrial function could present a potential therapeutic option for GBM treatment.

Circular RNA hsa_circ_0000282 contributes to osteosarcoma cell proliferation by regulating miR-192/XIAP axis

Background

Circular RNAs (circRNAs) have emerged as a novel category of non-coding RNA, which exhibit a pivotal effect on regulating gene expression and biological functions, yet how circRNAs function in osteosarcoma (OSA) still demands further investigation. This study aimed at probing into the function of hsa_circ_0000282 in OSA.

Methods

The expressions of circ_0000282 and miR-192 in OSA tissues and cell lines were examined by quantitative real-time polymerase chain reaction (qRT-PCR), and the correlation between the expression level of circ_0000282 and clinicopathological features of OSA patients was analyzed. The expressions of X-linked inhibitor of apoptosis protein (XIAP), B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in OSA cells were assayed by Western blot. The proliferation and apoptosis of OSA cells were examined by CCK-8, BrdU and flow cytometry, respectively. Bioinformatics analysis, dual-luciferase reporter gene assay and RIP experiments were employed to predict and validate the targeting relationships between circ_0000282 and miR-192, and between miR-192 and XIAP, respectively.

Results

Circ_0000282 was highly expressed in OSA tissues and cell lines, which represented positive correlation with Enneking stage of OSA patients and negative correlation with tumor differentiation degree. In vitro experiments confirmed that overexpression of circ_0000282 markedly facilitated OSA cell proliferation and repressed cancer cell apoptosis in comparison to control group. Besides, knockdown of circ_0000282 repressed OSA cell proliferation and promoted apoptosis. Additionally, the binding relationships between circ_0000282 and miR-192, and between miR-192 and XIAP were validated. Circ_0000282 indirectly up-regulated XIAP expression by adsorbing miR-192, thereby playing a role in promoting cancer in OSA.

Conclusion

Circ_0000282 was a novel oncogenic circRNA in OSA. Circ_0000282/miR-192/XIAP axis regulated OSA cell proliferation apoptosis with competitive endogenous RNA mechanism.

miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

BACKGROUND

miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.

METHODS

Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.

RESULTS

miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.

CONCLUSION

miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

Chronic exposure of human glioblastoma tumors to low concentrations of a pesticide mixture induced multidrug resistance against chemotherapy agents

Recent evidence indicates that chronic, low-dose exposure to mixtures of pesticides can cause adverse responses in a variety of cells, tissues and organs, although interactions between pesticides circulating in the blood and cancer cells remain largely unexplored. The aim of this study was to investigate the potential of a mixture of four pesticides to induce multidrug resistance against the chemotherapeutic agents cisplatin, 5-fluorouracil and temozolomide in the human U87 glioblastoma cell line, and to explore the molecular mechanisms underlying this resistance. We found that the repeated administration of the pesticide mixture (containing the insecticides chlorpyrifos-ethyl and deltamethrin, the fungicide metiram, and the herbicide glyphosate) induced a strong drug resistance in U87 cells. The resistance was durable and transferred to subsequent cell generations. In addition, we detected a significant over-expression of the ATP-binding cassette (ABC) membrane transporters P-gp/ABCB1 and BRCP/ABCG2 as well as a glutathione-S-transferase (GST)/M1-type cellular detoxification function, known to have important roles in multidrug resistance, thus providing molecular support for the acquired multidrug resistance phenotype and shedding light on the mechanism of resistance. We further determined that there was lower mortality in the resistant brain tumor cells and that the mitochondrial apoptosis pathway was activated at a lower rate after chemotherapy compared to non-resistant control cells. In addition, multidrug-resistant cells were found to have both higher motility and wound-healing properties, suggesting a greater metastatic potential. Our results suggest that the investigation of P-gp, BRCP and GST/M1 multidrug resistance gene expression and/or protein levels in biopsy specimens of brain tumor patients who were at risk of pesticide exposure could be beneficial in determining chemotherapy dose and prolonging patient survival.

Role of Ubiquitination in PTEN Cellular Homeostasis and Its Implications in GB Drug Resistance

Glioblastoma (GB) is the most common and aggressive brain malignancy, characterized by heterogeneity and drug resistance. PTEN, a crucial tumor suppressor, exhibits phosphatase-dependent (PI3K-AKT-mTOR pathway)/independent (nucleus stability) activities to maintain the homeostatic regulation of numerous physiological processes. Premature and absolute loss of PTEN activity usually tends to cellular senescence. However, monoallelic loss of PTEN is frequently observed at tumor inception, and absolute loss of PTEN activity also occurs at the late stage of gliomagenesis. Consequently, aberrant PTEN homeostasis, mainly regulated at the post-translational level, renders cells susceptible to tumorigenesis and drug resistance. Ubiquitination-mediated degradation or deregulated intracellular localization of PTEN hijacks cell growth rheostat control for neoplastic remodeling. Functional inactivation of PTEN mediated by the overexpression of ubiquitin ligases (E3s) renders GB cells adaptive to PTEN loss, which confers resistance to EGFR tyrosine kinase inhibitors and immunotherapies. In this review, we discuss how glioma cells develop oncogenic addiction to the E3s-PTEN axis, promoting their growth and proliferation. Antitumor strategies involving PTEN-targeting E3 ligase inhibitors can restore the tumor-suppressive environment. E3 inhibitors collectively reactivate PTEN and may represent next-generation treatment against deadly malignancies such as GB.

Study on the differentially expressed genes and signaling pathways in dermatomyositis using integrated bioinformatics method

Dermatomyositis is a common connective tissue disease. The occurrence and development of dermatomyositis is a result of multiple factors, but its exact pathogenesis has not been fully elucidated. Here, we used biological information method to explore and predict the major disease related genes of dermatomyositis and to find the underlying pathogenic molecular mechanism.The gene expression data of GDS1956, GDS2153, GDS2855, and GDS3417 including 94 specimens, 66 cases of dermatomyositis specimens and 28 cases of normal specimens, were obtained from the Gene Expression Omnibus database. The 4 microarray gene data groups were combined to get differentially expressed genes (DEGs). The gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichments of DEGs were operated by the database for annotation, visualization and integrated discovery and KEGG orthology based annotation system databases, separately. The protein-protein interaction networks of the DEGs were built from the STRING website. A total of 4097 DEGs were extracted from the 4 Gene Expression Omnibus datasets, of which 2213 genes were upregulated, and 1884 genes were downregulated. Gene ontology analysis indicated that the biological functions of DEGs focused primarily on response to virus, type I interferon signaling pathway and negative regulation of viral genome replication. The main cellular components include extracellular space, cytoplasm, and blood microparticle. The molecular functions include protein binding, double-stranded RNA binding and MHC class I protein binding. KEGG pathway analysis showed that these DEGs were mainly involved in the toll-like receptor signaling pathway, cytosolic DNA-sensing pathway, RIG-I-like receptor signaling pathway, complement and coagulation cascades, arginine and proline metabolism, phagosome signaling pathway. The following 13 closely related genes, XAF1, NT5E, UGCG, GBP2, TLR3, DDX58, STAT1, GBP1, PLSCR1, OAS3, SP100, IGK, and RSAD2, were key nodes from the protein-protein interaction network.This research suggests that exploring for DEGs and pathways in dermatomyositis using integrated bioinformatics methods could help us realize the molecular mechanism underlying the development of dermatomyositis, be of actual implication for the early detection and prophylaxis of dermatomyositis and afford reliable goals for the curing of dermatomyositis.

Induction of apoptosis through extrinsic/intrinsic pathways and suppression of ERK/NF-κB signalling participate in anti-glioblastoma of imipramine

Glioblastomas are the most aggressive type of brain tumour, with poor prognosis even after standard treatment such as surgical resection, temozolomide and radiation therapy. The overexpression of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in glioblastomas is recognized as an important treatment target. Thus, an urgent need regarding glioblastomas is the development of a new, suitable agent that may show potential for the inhibition of extracellular signal-regulated kinase (ERK)/NF-κB-mediated glioblastoma progression. Imipramine, a tricyclic antidepressant, has anti-inflammatory actions against inflamed glial cells; additionally, imipramine can induce glioblastoma toxicity via the activation of autophagy. However, whether imipramine can suppress glioblastoma progression via the induction of apoptosis and blockage of ERK/NF-κB signalling remains unclear. The main purpose of this study was to investigate the effects of imipramine on apoptotic signalling and ERK/NF-κB-mediated glioblastoma progression by using cell proliferation (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide [MTT] assay), flow cytometry, Western blotting, and cell invasion/migration assay analysis in vitro. The ERK and NF-κB inhibitory capacity of imipramine is detected by NF-κB reporter gene assay and Western blotting. Additionally, a glioblastoma-bearing animal model was used to validate the therapeutic efficacy and general toxicity of imipramine. Our results demonstrated that imipramine successfully triggered apoptosis through extrinsic/intrinsic pathways and suppressed the invasion/migration ability of glioblastoma cells. Furthermore, imipramine effectively suppressed glioblastoma progression in vivo via the inhibition of the ERK/NF-κB pathway. In summary, imipramine is a potential anti-glioblastoma drug which induces apoptosis and has the capacity to inhibit ERK/NF-κB signalling.

Evaluation of inhibitory effects of flavonoids on breast cancer resistance protein (BCRP): From library screening to biological evaluation to structure-activity relationship

Flavonoids are a group of polyphenols ubiquitously present in vegetables, fruits and herbal products, despite various known pharmacological activities, few researches have been done about the interaction of flavonoids with breast cancer resistance protein (BCRP). The present study was designed to investigate the inhibitory effects of 99 flavonoids on BCRP in vitro and in vivo and to clarify structure-activity relationships of flavonoids with BCRP. Eleven flavonoids, including amentoflavone, apigenin, biochanin A, chrysin, diosimin, genkwanin, hypericin, kaempferol, kaempferide, licochalcone A and naringenin, exhibited significant inhibition (>50%) on BCRP in BCRP-MDCKII cells, which reduced the BCRP-mediated efflux of doxorubicin and temozolomide, accordingly increased their cytotoxicity. In addition, co-administration of mitoxantrone with the 11 flavonoids increased the AUC0-t of mitoxantrone in different extents in rats. Among them, chrysin increased the AUC0-t most significantly, by 81.97%. Molecular docking analysis elucidated the inhibition of flavonoids on BCRP might be associated with Pi-Pi stacked interactions and/or potential Pi-Alkyl interactions, but not conventional hydrogen bonds. The pharmacophore model indicated the aromatic ring B, hydrophobic groups and hydrogen bond acceptors may play critical role in the potency of flavonoids inhibition on BCRP. Thus, our findings would provide helpful information for predicting the potential risks of flavonoid-containing food/herb-drug interactions in humans.

Triazole Bridged Flavonoid Dimers as Potent, Nontoxic, and Highly Selective Breast Cancer Resistance Protein (BCRP/ABCG2) Inhibitors

The present work describes the syntheses of diverse triazole bridged flavonoid dimers and identifies potent, nontoxic, and highly selective BCRP inhibitors. A homodimer, Ac22(Az8)₂, with m-methoxycarbonylbenzyloxy substitution at C-3 of the flavone moieties and a bis-triazole-containing linker (21 atoms between the two flavones) showed low toxicity (IC₅₀ toward L929, 3T3, and HFF-1 > 100 μM), potent BCRP-inhibitory activity (EC₅₀ = 1-2 nM), and high BCRP selectivity (BCRP selectivity over MRP1 and P-gp > 455-909). Ac22(Az8)₂ inhibits BCRP-ATPase activity, blocks the drug efflux activity of BCRP, elevates the intracellular drug accumulation, and finally restores the drug sensitivity of BCRP-overexpressing cells. It does not down-regulate the surface BCRP protein expression to enhance the drug retention. Therefore, Ac22(Az8)₂ and similar flavonoid dimers appear to be promising candidates for further development into combination therapy to overcome MDR cancers with BCRP overexpression.

Advancing towards Effective Glioma Therapy: MicroRNA Derived from Umbilical Cord Mesenchymal Stem Cells' Extracellular Vesicles

A glioma, especially a grade IV glioblastoma, is a malignant tumour with a poor prognosis despite growing medical advancements. Researchers have been looking for better and more effective treatments targeting the molecular pathways of gliomas due to glioblastomas’ ability to develop resistance to chemotherapies. Moreover, glioma stem cells (GSC) contribute to maintaining the glioma population, which benefits from its ability to self-renew and differentiate. Recent research has reported that through the introduction of umbilical cord mesenchymal stem cells (UCMSC) into glioma cells, the growth and development of the glioma cells can be downregulated. It has more currently been found out that UCMSC release extracellular vesicles (EVs) containing miRNA that are responsible for this phenomenon. Therefore, this review analyses literature to discuss all possible miRNAs contained within the UCMSC’s EVs and to elaborate on their molecular mechanisms in halting gliomas and GSC growth. This review will also include the challenges and limitations, to account for which more in vivo research is suggested. In conclusion, this review highlights how miRNAs contained within UCMSC’s EVs are able to downregulate multiple prominent pathways in the survival of gliomas.

Amentoflavone Effectively Blocked the Tumor Progression of Glioblastoma via Suppression of ERK/NF- κ B Signaling Pathway

Glioblastoma is the most common primary malignant tumor of the central nervous system, with an annual incidence of 5.26 per 100000 people. The clinical outcome of standard therapy and the survival rate remain poor; therefore, there is an unmet need for a new strategy to treat this lethal disease. Although amentoflavone was known to have anticancer potential in various types of cancers, its antiglioblastoma ability and mechanism remain unrecognized. We demonstrated that amentoflavone may suppress glioblastoma invasion and migration by transwell assay. Moreover, we established NF- κ B reporter gene system and used that for verifying NF- κ B inhibition efficacy of amentoflavone on in vitro and in vivo studies. Here, we indicated that amentoflavone not only diminished NF- κ B activation, but also reduced NF- κ B-mediated downstream oncogenes expression, such as MMP-2, MMP-9, XIAP, cyclinD1 and VEGF, which was elucidated by Western blot and immunohistochemistry (IHC). Tumor growth inhibition and NF- κ B reduction was found in the amentoflavone treatment group, which was revealed by the glioblastoma-bearing animal model. In this study, we also used ERK inhibitor and NF- κ B inhibitor (QNZ) to confirm whether the beneficial result of amentoflavone on glioblastoma was mainly regulated by blockage of ERK/NF- κ B signaling. In summary, ERK/NF- κ B signaling pathway has a role in the inhibition of tumor growth by amentoflavone in glioblastoma.

Prognostic Value of XIAP Level in Patients with Various Cancers: A Systematic Review and Meta-Analysis

Background: X-linked inhibitor of apoptosis protein (XIAP) plays an important role in cancer pathogenesis, which has been found to be overexpressed in multiple human cancers and associated with survival rates. Herein, we performed a meta-analysis to explore the predictive value of XIAP level in patients with various solid tumors. Methods: Relevant articles exploring the relationship between XIAP expression and survival of cancer patients were retrieved in PubMed, PMC, EMBASE and Web of Science published from 2001 to 2018. The combined hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate the significance. Results: A total of 6554 patients from 40 articles were included in this meta-analysis. It was shown in 37 studies with 4864 cases that the over-expression of XIAP was associated with poorer overall survival (OS) (combined HR=1.61, 95% CI: 1.33-1.96). Meanwhile, 8 studies with 1862 cases revealed that elevated XIAP level predicted shorter disease-free survival (DFS) (HR=2.17, 95% CI: 1.03-4.59). Subgroup analyses showed that higher XIAP detection was related to worse OS in gastric cancer (HR=1.42, 95% CI: 1.18-1.72) and head and neck cancer (HNC) (HR=2.97, 95% CI: 1.97-4.47). Conclusion: Our results suggested that elevated XIAP level seemed to represent an unfavorable prognostic factor for clinical outcomes in cancer patients. However, there were limited studies describing the association between XIAP expression and clinical prognosis in each different type of tumors. Therefore, concrete roles of XIAP in various cancers need to be further explored.

Immunohistochemical Characterization of Procaspase-3 Overexpression as a Druggable Target With PAC-1, a Procaspase-3 Activator, in Canine and Human Brain Cancers

Gliomas and meningiomas are the most common brain neoplasms affecting both humans and canines, and identifying druggable targets conserved across multiple brain cancer histologies and comparative species could broadly improve treatment outcomes. While satisfactory cure rates for low grade, non-invasive brain cancers are achievable with conventional therapies including surgery and radiation, the management of non-resectable or recurrent brain tumors remains problematic and necessitates the discovery of novel therapies that could be accelerated through a comparative approach, such as the inclusion of pet dogs with naturally-occurring brain cancers. Evidence supports procaspase-3 as a druggable brain cancer target with PAC-1, a pro-apoptotic, small molecule activator of procaspase-3 that crosses the blood-brain barrier. Procaspase-3 is frequently overexpressed in malignantly transformed tissues and provides a preferential target for inducing cancer cell apoptosis. While preliminary evidence supports procaspase-3 as a viable target in preclinical models, with PAC-1 demonstrating activity in rodent models and dogs with spontaneous brain tumors, the broader applicability of procaspase-3 as a target in human brain cancers, as well as the comparability of procaspase-3 expressions between differing species, requires further investigation. As such, a large-scale validation of procaspase-3 as a druggable target was undertaken across 651 human and canine brain tumors. Relative to normal brain tissues, procaspase-3 was overexpressed in histologically diverse cancerous brain tissues, supporting procaspase-3 as a broad and conserved therapeutic target. Additionally, procaspase-3 expressing glioma and meningioma cell lines were sensitive to the apoptotic effects of PAC-1 at biologically relevant exposures achievable in cancer patients. Importantly, the clinical relevance of procaspase-3 as a potential prognostic variable was demonstrated in human astrocytomas of variable histologic grades and associated clinical outcomes, whereby tumoral procaspase-3 expression was negatively correlated with survival; findings which suggest that PAC-1 might provide the greatest benefit for patients with the most guarded prognoses.

Signal transduction pathways and resistance to targeted therapies in glioma

Although surgical techniques and adjuvant therapies have undergone progressive development for decades, the therapeutic outcomes for treating glioblastoma (GBM) remain poor. The main reasons for the poor prognosis of gliomas are that limited tumor tissue that can be resected (to preserve brain functions) and that residual tumors are often resistant to irradiation and chemotherapy. Therefore, overcoming the resistance of residual tumors against adjuvant therapy is urgently needed for glioma treatment. Recent large cohort studies of genetic alterations in GBM demonstrated that both genetic information and intracellular molecular signaling are networked in gliomas and that such information may help clarify which molecules or signals serve essential roles in resistance against radiation or chemotherapy, highlighting them as potential novel therapeutic targets against refractory gliomas. In this review, we summarize the current understanding of molecular networks that govern glioma biology, mainly based on cohort studies or recent evidence, with a focus on how intracellular signaling molecules in gliomas associate with each other and regulate refractoriness against current therapy.

Benzyl isothiocyanate inhibits human brain glioblastoma multiforme GBM 8401 cell xenograft tumor in nude mice in vivo

Benzyl isothiocyanate (BITC), a member of isothiocyanates (ITCs), has been shown to induce cell death in many human cancer cells, but there is no further report to show BITC suppresses glioblastoma multiforme cells in vivo. In the present study, we investigate the effects of BITC on the inhibition of GBM 8401/luc2 cell generated tumor on athymic nude mice. We established a luciferase expressing stable clone named as GBM 8401/luc2. Thirty male mice were inoculated subcutaneously with GBM 8401/luc2 cells to generate xenograft tumor mice model. Group I was treated with 110 μL phosphate-buffered solution plus 10 μL dimethyl sulfoxide, Group II-III with BITC (5 or 10 μmol/100 μL/day, relatively). Mice were given oral treatment of BITC by gavage for 21 days. Results showed that BITC did not affect the body weights. After anesthetized, the photons emitted from mice tumor were detected with Xenogen IVIS imaging system 200 and higher dose of BITC have low total photon flux than that of lower dose of BITC. Results also showed that higher dose of BITC have low total tumor volumes and weights than that of low dose of BITC. Isolated tumors were investigated by immunohistochemical analysis and results showed that BITC at both dose of treatment weakly stained with anti-MCL1 and -XIAP. However, both dose of BITC treatments have strong signals of caspase-3 and Bax. Overall, these data demonstrated that BITC suppressed tumor properties in vivo. Overall, based on these observations, BITC can be used against human glioblastoma multiforme in the future.

Fabrication and Characterization of Chitosan-Hyaluronic Acid Scaffolds with Varying Stiffness for Glioblastoma Cell Culture

The invasive and recurrent nature of glioblastoma multiforme (GBM) is linked to a small subpopulation of cancer cells, which are self-renewing, resistant to standard treatment regimens, and induce formation of new tumors. Matrix stiffness is implicated in the regulation of cell proliferation, drug resistance, and reversion to a more invasive phenotype. Therefore, understanding the relationship between matrix stiffness and tumor cell behavior is vital to develop appropriate in vitro tumor models. Here, chitosan-hyaluronic acid (CHA) polyelectrolyte complex scaffolds are fabricated with statistically significant stiffness variances to characterize the effect of scaffold stiffness on morphology, proliferation, drug resistance, and gene expression in human glioblastoma cells (U-87 MG). All scaffolds support GBM proliferation over a 12-day culture period, yet larger spheroids are observed in scaffolds with higher stiffness. Additionally, GBM cells cultured in stiffer CHA scaffolds prove significantly more resistant to the common chemotherapeutic temozolomide. Moreover, the stiffer 8% CHA scaffolds exhibit an increase in expression of drug resistance and invasion related genes compared to 2D culture. CHA scaffolds present a tunable microenvironment for enhanced tumor cell malignancy and may provide a valuable in vitro microenvironment for studying tumor progression and screening anticancer therapies.

High expression of XIAP and Bcl-2 may inhibit programmed cell death in glioblastomas

ABSTRACT Glioblastoma (GBM) is the most malignant glioma and represents 29% of all brain tumors. Tumorigenesis is intimately connected with characteristics acquired in the physiologic pathway of cellular death. Objective: In the present study, the expression of anti-apoptotic (XIAP and Bcl-2) and apoptotic (cytochrome C, caspase 9, APAF-1), caspase 3 and the Smac/DIABLO genes related to the apoptosis pathway were evaluated in 30 samples of glioblastoma. Methods: The gene expression was evaluated in 30 glioblastomas (WHO grade IV) and compared to 10 white matter control samples with real-time PCR. Results and Conclusion: There were higher expressions of XIAP (p = 0.0032) and Bcl-2 (p = 0.0351) in the glioblastoma samples compared to the control samples of normal brain. These results raise the question of whether Bcl-2 and XIAP genes can be responsible for the inhibition of programmed cell death in glioblastomas. Moreover, they provide additional information capable of allowing the development of new target therapy strategies.

Obstacles to Brain Tumor Therapy: Key ABC Transporters

The delivery of cancer chemotherapy to treat brain tumors remains a challenge, in part, because of the inherent biological barrier, the blood-brain barrier. While its presence and role as a protector of the normal brain parenchyma has been acknowledged for decades, it is only recently that the important transporter components, expressed in the tightly knit capillary endothelial cells, have been deciphered. These transporters are ATP-binding cassette (ABC) transporters and, so far, the major clinically important ones that functionally contribute to the blood-brain barrier are ABCG2 and ABCB1. A further limitation to cancer therapy of brain tumors or brain metastases is the blood-tumor barrier, where tumors erect a barrier of transporters that further impede drug entry. The expression and regulation of these two transporters at these barriers, as well as tumor derived alteration in expression and/or mutation, are likely obstacles to effective therapy.

S100A4 Is a Biomarker and Regulator of Glioma Stem Cells That Is Critical for Mesenchymal Transition in Glioblastoma

Glioma stem cells (GSC) and epithelial-mesenchymal transition (EMT) are strongly associated with therapy resistance and tumor recurrence, but the underlying mechanisms are incompletely understood. Here, we show that S100A4 is a novel biomarker of GSCs. S100A4⁺ cells in gliomas are enriched with cancer cells that have tumor-initiating and sphere-forming abilities, with the majority located in perivascular niches where GSCs are found. Selective ablation of S100A4-expressing cells was sufficient to block tumor growth in vitro and in vivo We also identified S100A4 as a critical regulator of GSC self-renewal in mouse and patient-derived glioma tumorspheres. In contrast with previous reports of S100A4 as a reporter of EMT, we discovered that S100A4 is an upstream regulator of the master EMT regulators SNAIL2 and ZEB along with other mesenchymal transition regulators in glioblastoma. Overall, our results establish S100A4 as a central node in a molecular network that controls stemness and EMT in glioblastoma, suggesting S100A4 as a candidate therapeutic target. Cancer Res; 77(19); 5360-73. ©2017 AACR.