bims-malgli Biomed News
on Biology of malignant gliomas
Issue of 2020‒08‒23
twenty-one papers selected by
Oltea Sampetrean
Keio University

  1. Neuro Oncol. 2020 Aug 19. pii: noaa198. [Epub ahead of print]
    Nie E, Jin X, Miao F, Yu T, Zhi T, Shi Z, Wang Y, Zhang J, Xie M, You Y.
      BACKGROUND: Our previous studies have indicated that miR-198 reduces cellular methylguanine DNA methyltransferase (MGMT) levels to enhance temozolomide sensitivity. Transforming growth factor beta 1 (TGF-β1) switches off miR-198 expression by repressing K-homology splicing regulatory protein (KSRP) expression in epidermal keratinocytes. However, the underlying role of TGF-β1 in temozolomide resistance has remained unknown.METHODS: The distribution of KSRP was detected by Western blotting and immunofluorescence. Microarray analysis was used to compare the levels of long non-coding RNAs (lncRNAs) between TGF-β1-treated and untreated cells. RNA immunoprecipitation was performed to verify the relationship between RNAs and KSRP. Flow cytometry and orthotopic and subcutaneous xenograft tumor models were used to determine the function of TGF-β1 in temozolomide resistance.
    RESULTS: Overexpression of TGF-β1 contributed to temozolomide resistance in MGMT-promoter hypomethylated glioblastoma cells in vitro and in vivo. TGF-β1 treatment reduced cellular MGMT levels through suppressing the expression of miR-198. However, TGF-β1 upregulation did not affect KSRP expression in glioma cells. We identified and characterized two lncRNAs (H19 and HOXD-AS2) that were upregulated by TGF-β1 through SMAD signaling. H19 and HOXD-AS2 exhibited competitive binding to KSRP and prevented KSRP from binding to pri-miR-198, thus decreasing miR-198 expression. HOXD-AS2 or H19 upregulation strongly promoted temozolomide resistance and MGMT expression. Moreover, KSRP depletion abrogated the effects of TGF-β1 and lncRNAs on miR-198 and MGMT. Finally, we found that patients with low-levels of TGF-β1 or lncRNA expression benefited from temozolomide therapy.
    CONCLUSIONS: Our results reveal an underlying mechanism by which TGF-β1 confers temozolomide resistance. Furthermore, our findings suggest that a novel combination of temozolomide with a TGF-β inhibitor may serve as an effective therapy for glioblastomas.
    Keywords:  KSRP; MGMT; TGF-β1; glioblastoma; temozolomide resistance
  2. Nat Commun. 2020 Aug 17. 11(1): 4116
    Sharanek A, Burban A, Laaper M, Heckel E, Joyal JS, Soleimani VD, Jahani-Asl A.
      Glioblastoma contains a rare population of self-renewing brain tumor stem cells (BTSCs) which are endowed with properties to proliferate, spur the growth of new tumors, and at the same time, evade ionizing radiation (IR) and chemotherapy. However, the drivers of BTSC resistance to therapy remain unknown. The cytokine receptor for oncostatin M (OSMR) regulates BTSC proliferation and glioblastoma tumorigenesis. Here, we report our discovery of a mitochondrial OSMR that confers resistance to IR via regulation of oxidative phosphorylation, independent of its role in cell proliferation. Mechanistically, OSMR is targeted to the mitochondrial matrix via the presequence translocase-associated motor complex components, mtHSP70 and TIM44. OSMR interacts with NADH ubiquinone oxidoreductase 1/2 (NDUFS1/2) of complex I and promotes mitochondrial respiration. Deletion of OSMR impairs spare respiratory capacity, increases reactive oxygen species, and sensitizes BTSCs to IR-induced cell death. Importantly, suppression of OSMR improves glioblastoma response to IR and prolongs lifespan.
  3. Int J Mol Sci. 2020 Aug 13. pii: E5809. [Epub ahead of print]21(16):
    Linhares P, Carvalho B, Vaz R, Costa BM.
      Glioblastoma (GBM) is the most frequent malignant primary brain tumor in adults, characterized by a highly aggressive, inflammatory and angiogenic phenotype. It is a remarkably heterogeneous tumor at several levels, including histopathologically, radiographically and genetically. The 2016 update of the WHO Classification of Tumours of the Central Nervous System highlighted molecular parameters as paramount features for the diagnosis, namely IDH1/2 mutations that distinguish primary and secondary GBM. An ideal biomarker is a molecule that can be detected/quantified through simple non- or minimally invasive methods with the potential to assess cancer risk; promote early diagnosis; increase grading accuracy; and monitor disease evolution and treatment response, as well as fundamentally being restricted to one aspect. Blood-based biomarkers are particularly attractive due to their easy access and have been widely used for various cancer types. A number of serum biomarkers with multiple utilities for glioma have been reported that could classify glioma grades more precisely and provide prognostic value among these patients. At present, screening for gliomas has no clinical relevance. This is because of the low incidence, the lack of sensitive biomarkers in plasma, and the observation that gliomas may develop apparently de novo within few weeks or months. To the best of our knowledge, there is no routine use of a serum biomarker for clinical follow-up. The purpose of this paper is to review the serum biomarkers described in the literature related to glioblastoma and their possible relationship with clinical features.
    Keywords:  biomarkers; diagnosis; glioblastoma; prognosis
  4. Cell Death Dis. 2020 Aug 21. 11(8): 668
    Chen WJ, Zhang X, Han H, Lv JN, Kang EM, Zhang YL, Liu WP, He XS, Wang J, Wang GH, Yu YB, Zhang W.
      Inter- and intratumoral heterogeneity is a hallmark of glioblastoma (GBM) that facilitates recurrence, treatment resistance, and worse prognosis. O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is a significant prognostic marker for Temozolomide (TMZ) resistance in GBM patients. YKL-40 is a molecular marker for the mesenchymal subtype of GBMs and is responsible for TMZ resistance. However, underlying mechanisms by which MGMT epigenetics impacts patient outcomes and the function of YKL-40 are not fully determined. Herein, we performed in vitro and in vivo experiments, six human IDH1/2 wild-type glioblastoma stem-like cells (GSCs) were established and studied to further determine a potential interaction of YKL-40 and MGMT promoter methylation. We demonstrated that YKL-40 functioned differently in human IDH1/2 wild-type GSCs. In MGMT promoter-methylated (MGMT-m) GSCs, it acted as a tumor suppressor gene. On the other hand, in MGMT promoter-unmethylated (MGMT-um) GSCs, it promoted tumorigenesis. Notably, the reason that YKL-40 played different roles in GSCs could not be interpreted by the molecular classification of each GSCs, but is a function of MGMT promoter methylation status and involves the RAS-MEK-ERK pathway. YKL-40 mediated TMZ sensitivity by activating DNA damage responses (DDRs) in MGMT-m GSCs, and it mediated resistance to TMZ by inhibiting DDRs in MGMT-um GSCs. Our report demonstrated that MGMT promoter methylation status might influence a gene's function in human cancer. Moreover, our data also highlight the point that gene function should be investigated not only according to the molecular tumor classification, but also the epigenetic signature.
  5. J Immunother Cancer. 2020 Aug;pii: e000207. [Epub ahead of print]8(2):
    Zheng Z, Zhang J, Jiang J, He Y, Zhang W, Mo X, Kang X, Xu Q, Wang B, Huang Y.
      BACKGROUND: Glioblastoma (GBM) treatment is undermined by the suppressive tumor immune microenvironment (TIME). Seek for effective methods for brain TIME modulation is a pressing need. However, there are two major challenges against achieving the goal: first, to screen the effective drugs with TIME-remodeling functions and, second, to develop a brain targeting system for delivering the drugs.METHODS: In this study, an α7 nicotinic acetylcholine receptors (nAChRs)-binding peptide DCDX was used to modify the codelivery liposomes to achieve a 'three-birds-one-stone' delivery strategy, that is, multi-targeting the glioma vessel endothelium, glioma cells, and tumor-associated macrophages that all overexpressed α7 nAChRs. A brain-targeted liposomal honokiol and disulfiram/copper codelivery system (CDX-LIPO) was developed for combination therapy via regulating mTOR (mammalian target of rapamycin) pathway for remodeling tumor metabolism and TIME. Honokiol can yield a synergistic effect with disulfiram/copper for anti-GBM.
    RESULTS: It was demonstrated that CDX-LIPO remarkably triggered tumor cell autophagy and induced immunogenic cell death, and meanwhile, activated the tumor-infiltrating macrophage and dendritic cells, and primed T and NK (natural killer) cells, resulting in antitumor immunity and tumor regression. Moreover, CDX-LIPO promoted M1-macrophage polarization and facilitated mTOR-mediated reprogramming of glucose metabolism in glioma.
    CONCLUSION: This study developed a potential combinatory therapeutic strategy by regulation of TIME and a 'three-birds-one-stone'-like glioma-targeting drug delivery system.
    Keywords:  brain neoplasms; immunotherapy; macrophages; tumor microenvironment
  6. Mol Cancer Res. 2020 Aug 14. pii: molcanres.0099.2020. [Epub ahead of print]
    Senthil Kumar S, Sengupta S, Zhu X, Mishra DK, Phoenix T, Dyer L, Fuller C, Stevenson CB, DeWire M, Fouladi M, Drissi R.
      Diffuse intrinsic pontine glioma (DIPG) is a poor-prognosis pediatric brain tumor with a median survival of less than one year. No effective therapy is currently available, and no therapeutic advances have been made in several decades. We have previously identified BMI-1 as a potential therapeutic target in DIPG and have shown that BMI-1 is highly expressed in DIPG tumors regardless of histone 3 subtype. In the present study, we show that the modulation of BMI-1 leads to DNA damage, M phase cell cycle arrest, chromosome scattering and cell death. Interestingly, EZH2 inhibition did not alter these effects. Furthermore, modulation of BMI-1 sensitizes DIPG patient-derived stem-like cells to ionizing radiation (IR). Treatment of DIPG stem-like cells with PTC596, a BMI-1 modulator, and IR, impairs the kinetics of DNA damage response (DDR). Both DDR foci formation and resolution were delayed, resulting in further reduction in cell viability compared with either treatment alone. In vivo, treatment of mice bearing DIPG xenografts with PTC596 leads to decreased tumor volume and growth kinetics, increased intratumoral apoptosis and sustained animal survival benefit. Gene expression analysis indicates that BMI-1 expression correlates positively with DIPG stemness and BMI-1 signature. At the single-cell level, the analysis reveals that BMI-1 pathway is upregulated in undifferentiated cells and positively correlates with stemness in DIPG tumors. Implications: Together, our findings indicate that BMI-1 modulation is associated with mitotic abnormalities, impaired DDR and cell death, supporting the combination of BMI-1 modulation and radiation as a promising novel therapy for children with DIPG.
  7. Cancer Res. 2020 Aug 15. 80(16): 3195-3196
    Koncar RF, Agnihotri S.
      Glioma stem-like cells (GSC) in glioblastoma (GBM) structure tumor cells into a hierarchical organization and are postulated to be recalcitrant to conventional treatments, resulting in fatal relapse of the disease. A better understanding of these cells would be essential for meaningful and lasting treatments. In this issue of Cancer Research, Virolle and colleagues report a fascinating phenotype whereby the extracellular signal-regulated kinase (ERK) pathway regulates a mechanism of dedifferentiation of GBM cells into a stem-like state expressing markers of pluripotency through an EGFR-ERK-EGR1-dependent axis. This aptly termed "toggle switch" may contribute to maintenance of GSCs, promote intratumor heterogeneity, and potentially provide innovative treatment options.See related article by Almairac et al., p. 3236.
  8. Cancers (Basel). 2020 Aug 13. pii: E2266. [Epub ahead of print]12(8):
    Colella B, Colardo M, Iannone G, Contadini C, Saiz-Ladera C, Fuoco C, Barilà D, Velasco G, Segatto M, Di Bartolomeo S.
      Epidermal Growth Factor receptor (EGFR) is a tyrosine kinase receptor widely expressed on the surface of numerous cell types, which activates several downstream signalling pathways involved in cell proliferation, migration and survival. EGFR alterations, such as overexpression or mutations, have been frequently observed in several cancers, including glioblastoma (GBM), and are associated to uncontrolled cell proliferation. Here we show that the inhibition of mammalian target of Rapamycin (mTOR) mediates EGFR delivery to lysosomes for degradation in GBM cells, independently of autophagy activation. Coherently with EGFR internalisation and degradation, mTOR blockade negatively affects the mitogen activated protein/extracellular signal-regulated kinase (MAPK)/ERK pathway. Furthermore, we provide evidence that Src kinase activation is required for EGFR internaliation upon mTOR inhibition. Our results further support the hypothesis that mTOR targeting may represent an effective therapeutic strategy in GBM management, as its inhibition results in EGFR degradation and in proliferative signal alteration.
    Keywords:  EGFR; autophagy; glioma; mTOR
  9. ACS Nano. 2020 Aug 06.
    Kinoh H, Quader S, Shibasaki H, Liu X, Maity A, Yamasoba T, Cabral H, Kataoka K.
      Glioblastoma (GBM) is resistant to immune checkpoint inhibition due to its low mutation rate, phosphatase and tensin homologue (PTEN)-deficient immunosuppressive microenvironment, and high fraction of cancer stem-like cells (CSCs). Nanomedicines fostering immunoactivating intratumoral signals could reverse GBM resistance to immune checkpoint inhibitors (ICIs) for promoting curative responses. Here, we applied pH-sensitive epirubicin-loaded micellar nanomedicines, which are under clinical evaluation, to synergize the efficacy of anti-PD1antibodies (aPD1) against PTEN-positive and PTEN-negative orthotopic GBM, the latter with a large subpopulation of CSCs. The combination of epirubicin-loaded micelles (Epi/m) with aPD1 overcame GBM resistance to ICIs by transforming cold GBM into hot tumors with high infiltration of antitumor immune cells through the induction of immunogenic cell death (ICD), elimination of immunosuppressive myeloid-derived suppressor cells (MSDCs), and reduction of PD-L1 expression on tumor cells. Thus, Epi/m plus aPD1 eradicated both PTEN-positive and PTEN-negative orthotopic GBM and provided long-term immune memory effects. Our results indicate the high translatable potential of Epi/m plus aPD1 for the treatment of GBM.
    Keywords:  anti-PD1 antibodies; epirubicin; glioblastoma; immune checkpoint inhibitor; polymeric micelles
  10. Cancers (Basel). 2020 Aug 19. pii: E2347. [Epub ahead of print]12(9):
    Soubéran A, Tchoghandjian A.
      Fifteen years after the establishment of the Stupp protocol as the standard of care to treat glioblastomas, no major clinical advances have been achieved and increasing patient's overall survival remains a challenge. Nevertheless, crucial molecular and cellular findings revealed the intra-tumoral and inter-tumoral complexities of these incurable brain tumors, and the essential role played by cells of the microenvironment in the lack of treatment efficacy. Taking this knowledge into account, fulfilling gaps between preclinical models and clinical samples is necessary to improve the successful rate of clinical trials. Since the beginning of the characterization of brain tumors initiated by Bailey and Cushing in the 1920s, several glioblastoma models have been developed and improved. In this review, we focused on the most widely used 3D human glioblastoma models, including spheroids, tumorospheres, organotypic slices, explants, tumoroids and glioblastoma-derived from cerebral organoids. We discuss their history, development and especially their usefulness.
    Keywords:  explants; glioblastomas; organoids; organotypic slices; preclinical 3D cancer models; spheroids; tumoroids; tumorospheres
  11. Oncogene. 2020 Aug 20.
    Liu Y, Yang L, Liao F, Wang W, Wang ZF.
      Glioma reported to be refractory to EGFR tyrosine kinase inhibitor is the most common malignant tumor in central nervous system. Our research showed the low expression of miR-450a-5p and high expression of EGFR in glioma tissues. MiR-450a-5p was also observed to synergize with gefitinib to inhibit the proliferation, migration and invasion and induce the apoptosis and autophagy of glioma cells. Furthermore, miR-450a-5p was demonstrated to target 3'UTR of EGFR, and regulated EGFR-induced PI3K/AKT/mTOR signaling pathway. Moreover, the above effects induced by miR-450a-5p in glioma cells were reversed by WIPI1 silencing. The inhibition role of miR-450a-5p on glioma growth was also confirmed in vivo by subcutaneous and intracranial tumor xenografts. Therefore, we conclude that miR-450a-5p synergizes with gefitinib to inhibit the glioma tumorigenesis through inducing autophagy by regulating the EGFR-induced PI3K/AKT/mTOR signaling pathway, thereby enhancing the drug sensitivity of gefitinib.
  12. Cell Death Dis. 2020 Aug 14. 11(8): 630
    Wang C, He C, Lu S, Wang X, Wang L, Liang S, Wang X, Piao M, Cui J, Chi G, Ge P.
      Induction of lethal autophagy has become a strategy to eliminate glioma cells, but it remains elusive whether autophagy contributes to cell death via causing mitochondria damage and nuclear translocation of apoptosis inducing factor (AIF). In this study, we find that silibinin induces AIF translocation from mitochondria to nuclei in glioma cells in vitro and in vivo, which is accompanied with autophagy activation. In vitro studies reveal that blocking autophagy with 3MA, bafilomycin A1 or by knocking down ATG5 with SiRNA inhibits silibinin-induced mitochondrial accumulation of superoxide, AIF translocation from mitochondria to nuclei and glioma cell death. Mechanistically, silibinin activates autophagy through depleting ATP by suppressing glycolysis. Then, autophagy improves intracellular H2O2 via promoting p53-mediated depletion of GSH and cysteine and downregulation of xCT. The increased H2O2 promotes silibinin-induced BNIP3 upregulation and translocation to mitochondria. Knockdown of BNIP3 with SiRNA inhibits silibinin-induced mitochondrial depolarization, accumulation of mitochondrial superoxide, and AIF translocation from mitochondria to nuclei, as well as prevents glioma cell death. Furthermore, we find that the improved H2O2 reinforces silibinin-induced glycolysis dysfunction. Collectively, autophagy contributes to silibinin-induced glioma cell death via promotion of oxidative stress-mediated BNIP3-dependent nuclear translocation of AIF.
  13. Oncogene. 2020 Aug 14.
    Sabbagh Q, Andre-Gregoire G, Guevel L, Gavard J.
      Although rare, glioblastoma is a devastating tumor of the central nervous system characterized by a poor survival and an extremely dark prognosis, making its diagnosis, treatment, and monitoring highly challenging. Numerous studies have highlighted extracellular vesicles (EVs) as key players of tumor growth, invasiveness, and resistance, as they carry oncogenic material. Moreover, EVs have been shown to communicate locally in a paracrine way but also at remote throughout the organism. Indeed, recent reports demonstrated the presence of brain tumor-derived EVs into body fluids such as plasma and cerebrospinal fluid. Fluid-associated EVs have indeed been suspected to reflect quantitative and qualitative information about the status and fate of the tumor and can potentially act as a resource for noninvasive biomarkers that might assist in diagnosis, treatment, and follow-up of glioblastoma patients. Here, we coined the name vesiclemia to define the concentration of plasmatic EVs, an intuitive term to be directly transposed in the clinical jargon.
  14. Commun Biol. 2020 Aug 17. 3(1): 450
    Koike N, Kota R, Naito Y, Hayakawa N, Matsuura T, Hishiki T, Onishi N, Fukada J, Suematsu M, Shigematsu N, Saya H, Sampetrean O.
      Under hypoxic conditions, nitroimidazoles can replace oxygen as electron acceptors, thereby enhancing the effects of radiation on malignant cells. These compounds also accumulate in hypoxic cells, where they can act as cytotoxins or imaging agents. However, whether these effects apply to cancer stem cells has not been sufficiently explored. Here we show that the 2-nitroimidazole doranidazole potentiates radiation-induced DNA damage in hypoxic glioma stem cells (GSCs) and confers a significant survival benefit in mice harboring GSC-derived tumors in radiotherapy settings. Furthermore, doranidazole and misonidazole, but not metronidazole, manifested radiation-independent cytotoxicity for hypoxic GSCs that was mediated by ferroptosis induced partially through blockade of mitochondrial complexes I and II and resultant metabolic alterations in oxidative stress responses. Doranidazole also limited the growth of GSC-derived subcutaneous tumors and that of tumors in orthotopic brain slices. Our results thus reveal the theranostic potential of 2-nitroimidazoles as ferroptosis inducers that enable targeting GSCs in their hypoxic niche.
  15. Cancers (Basel). 2020 Aug 19. pii: E2334. [Epub ahead of print]12(9):
    Yang M, Oh IY, Mahanty A, Jin WL, Yoo JS.
      Glioblastoma is the most lethal intracranial primary malignancy by no optimal treatment option. Cancer immunotherapy has achieved remarkable survival benefits against various advanced tumors, such as melanoma and non-small-cell lung cancer, thus triggering great interest as a new therapeutic strategy for glioblastoma. Moreover, the central nervous system has been rediscovered recently as a region for active immunosurveillance. There are vibrant investigations for successful glioblastoma immunotherapy despite the fact that initial clinical trial results are somewhat disappointing with unique challenges including T-cell dysfunction in the patients. This review will explore the potential of current immunotherapy modalities for glioblastoma treatment, especially focusing on major immune checkpoint inhibitors and the future strategies with novel targets and combo therapies. Immune-related adverse events and clinical challenges in glioblastoma immunotherapy are also summarized. Glioblastoma provides persistent difficulties for immunotherapy with a complex state of patients' immune dysfunction and a variety of constraints in drug delivery to the central nervous system. However, rational design of combinational regimens and new focuses on myeloid cells and novel targets to circumvent current limitations hold promise to advent truly viable immunotherapy for glioblastoma.
    Keywords:  glioblastoma; immune-checkpoint inhibitors; immune-related adverse events; tumor microenvironment; tumor-associated macrophages and microglia
  16. Cell Death Differ. 2020 Aug 19.
    Ji J, Ding K, Luo T, Zhang X, Chen A, Zhang D, Li G, Thorsen F, Huang B, Li X, Wang J.
      NF-κB signaling plays a critical role in tumor growth and treatment resistance in GBM as in many other cancers. However, the molecular mechanisms underlying high, constitutive NF-κB activity in GBM remains to be elucidated. Here, we screened a panel of tripartite motif (TRIM) family proteins and identified TRIM22 as a potential activator of NF-κB using an NF-κB driven luciferase reporter construct in GBM cell lines. Knockout of TRIM22 using Cas9-sgRNAs led to reduced GBM cell proliferation, while TRIM22 overexpression enhanced proliferation of cell populations, in vitro and in an orthotopic xenograft model. However, two TRIM22 mutants, one with a critical RING-finger domain deletion and the other with amino acid changes at two active sites of RING E3 ligase (C15/18A), were both unable to promote GBM cell proliferation over controls, thus implicating E3 ligase activity in the growth-promoting properties of TRIM22. Co-immunoprecipitations demonstrated that TRIM22 bound a negative regulator of NF-κB, NF-κB inhibitor alpha (IκBα), and accelerated its degradation by inducing K48-linked ubiquitination. TRIM22 also formed a complex with the NF-κB upstream regulator IKKγ and promoted K63-linked ubiquitination, which led to the phosphorylation of both IKKα/β and IκBα. Expression of a non-phosphorylation mutant, srIκBα, inhibited the growth-promoting properties of TRIM22 in GBM cell lines. Finally, TRIM22 was increased in a cohort of primary GBM samples on a tissue microarray, and high expression of TRIM22 correlated with other clinical parameters associated with progressive gliomas, such as wild-type IDH1 status. In summary, our study revealed that TRIM22 activated NF-κB signaling through posttranslational modification of two critical regulators of NF-κB signaling in GBM cells.
  17. Antioxidants (Basel). 2020 Aug 14. pii: E747. [Epub ahead of print]9(8):
    Krawczynski K, Godlewski J, Bronisz A.
      Rapid growth of brain tumors such as glioblastoma often results in oxygen deprivation and the emergence of hypoxic zones. In consequence, the enrichment of reactive oxygen species occurs, harming nonmalignant cells and leading them toward apoptotic cell death. However, cancer cells survive such exposure and thrive in a hypoxic environment. As the mechanisms responsible for such starkly different outcomes are not sufficiently explained, we aimed to explore what transcriptome rearrangements are used by glioblastoma cells in hypoxic areas. Using metadata analysis of transcriptome in different subregions of the glioblastoma retrieved from the Ivy Glioblastoma Atlas Project, we created the reactive oxygen species-dependent map of the transcriptome. This map was then used for the analysis of differential gene expression in the histologically determined cellular tumors and hypoxic zones. The gene ontology analysis cross-referenced with the clinical data from The Cancer Genome Atlas revealed that the metabolic shift is one of the major prosurvival strategies applied by cancer cells to overcome hypoxia-related cytotoxicity.
    Keywords:  cancer niche; glioblastoma; hypoxia; oxidative stress; tumor microenvironment
  18. Cancer Discov. 2020 Aug 21.
      A mouse study suggests that daily doses of a CSF1R inhibitor after radiation therapy can reduce the likelihood of glioblastoma recurrence. Mice that received the inhibitor lived more than twice as long as control animals, and only 20% of them developed recurrent tumors, whereas all control animals did.
  19. Antioxidants (Basel). 2020 Aug 20. pii: E773. [Epub ahead of print]9(9):
    Escoll M, Lastra D, Robledinos-Antón N, Wandosell F, Antón IM, Cuadrado A.
      Due to their high metabolic rate, tumor cells produce exacerbated levels of reactive oxygen species that need to be under control. Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP) is a scaffold protein with multiple yet poorly understood functions that participates in tumor progression and promotes cancer cell survival. However, its participation in the control of oxidative stress has not been addressed yet. We show that WIP depletion increases the levels of reactive oxygen species and reduces the levels of transcription factor NRF2, the master regulator of redox homeostasis. We found that WIP stabilizes NRF2 by restraining the activity of its main NRF2 repressor, the E3 ligase adapter KEAP1, because the overexpression of a NRF2ΔETGE mutant that is resistant to targeted proteasome degradation by KEAP1 or the knock-down of KEAP1 maintains NRF2 levels in the absence of WIP. Mechanistically, we show that the increased KEAP1 activity in WIP-depleted cells is not due to the protection of KEAP1 from autophagic degradation, but is dependent on the organization of the Actin cytoskeleton, probably through binding between KEAP1 and F-Actin. Our study provides a new role of WIP in maintaining the oxidant tolerance of cancer cells that may have therapeutic implications.
    Keywords:  antioxidants; cytoskeleton; oxidative stress; redox
  20. Semin Cancer Biol. 2020 Aug 16. pii: S1044-579X(20)30173-5. [Epub ahead of print]
    Afshari AR, Mollazadeh H, Henney NC, Jamialahmad T, Sahebkar A.
      Evidence from preclinical studies suggests that the competitive HMG-CoA reductase (HMGCR) inhibitors universally known as 'statins,' in addition to being powerful drugs that reduce cholesterol and improve cardiovascular risk, also have promising antitumor properties. Statins appear to enhance the treatment outcome of various cancers before and concurrent with other cancer treatment interventions. Glioblastoma multiforme (GBM), a particularly invasive cerebral tumor associated with high mortality, holds a poor median overall survival (OS) of around one year after surgical resection followed by concurrent radiation and chemotherapy. Recently, statins have increasingly appeared as potential adjuvant drugs for the treatment of GBM because of their potential to suppress cell growth, survival, migration, metastasis, inflammation, angiogenesis, and promote apoptosis during both in vitro and in vivo studies. However, the clinical outcomes of statins on the survival of patients with GBM are still controversial. This study aims to review and address some of the documented effects of statin drugs when focusing entirely on cancer treatment, especially GBM, including concurrent statin therapy with chemotherapeutic agents.
    Keywords:  Antitumor; Apoptosis; Cholesterol; Glioblastoma multiforme; Statin