scholarly journals Temozolomide antagonizes oncolytic immunovirotherapy in glioblastoma

2020 ◽  
Vol 8 (1) ◽  
pp. e000345 ◽  
Author(s):  
Dipongkor Saha ◽  
Samuel D Rabkin ◽  
Robert L Martuza
Keyword(s):  
Dna Methyltransferase ◽  
Standard Of Care ◽  
Interleukin 12 ◽  
Current Standard ◽  
Antitumor Effects ◽  
Methylguanine Dna Methyltransferase ◽  
Beneficial Effects ◽  
Simplex Virus

BackgroundTemozolomide (TMZ) chemotherapy is a current standard of care for glioblastoma (GBM), however it has only extended overall survival by a few months. Because it also modulates the immune system, both beneficially and negatively, understanding how TMZ interacts with immunotherapeutics is important. Oncolytic herpes simplex virus (oHSV) is a new class of cancer therapeutic with both cytotoxic and immunostimulatory activities. Here, we examine the combination of TMZ and an oHSV encoding murine interleukin 12, G47Δ-mIL12, in a mouse immunocompetent GBM model generated from non-immunogenic 005 GBM stem-like cells (GSCs.MethodsWe first investigated the cytotoxic effects of TMZ and/or G47Δ-IL12 treatments in vitro, and then the antitumor effects of combination therapy in vivo in orthotopically implanted 005 GSC-derived brain tumors. To improve TMZ sensitivity, O6-methylguanine DNA methyltransferase (MGMT) was inhibited. The effects of TMZ on immune cells were evaluated by flow cytometery and immunohistochemistry.ResultsThe combination of TMZ+G47Δ-IL12 kills 005 GSCs in vitro better than single treatments. However, TMZ does not improve the survival of orthotopic tumor-bearing mice treated with G47Δ-IL12, but rather can abrogate the beneficial effects of G47Δ-IL12 when the two are given concurrently. TMZ negatively affects intratumor T cells and macrophages and splenocytes. Addition of MGMT inhibitor O6-benzylguanine (O6-BG), an inactivating pseudosubstrate of MGMT, to TMZ improved survival, but the combination with G47Δ-IL12 did not overcome the antagonistic effects of TMZ treatment on oHSV therapy.ConclusionsThese results illustrate that chemotherapy can adversely affect oHSV immunovirotherapy. As TMZ is the standard of care for GBM, the timing of these combined therapies should be taken into consideration when planning oHSV clinical trials with chemotherapy for GBM.

scholarly journals Riluzole enhances the antitumor effects of temozolomide via suppression of MGMT expression in glioblastoma

2020 ◽  
pp. 1-10 ◽  
Author(s):  
Tetsuya Yamada ◽  
Shohei Tsuji ◽  
Shinsuke Nakamura ◽  
Yusuke Egashira ◽  
Masamitsu Shimazawa ◽  
...  
Keyword(s):  
Cell Lines ◽  
Dna Methyltransferase ◽  
Antitumor Effect ◽  
Metabotropic Glutamate Receptor ◽  
Migration And Invasion ◽  
Antitumor Effects ◽  
Mgmt Expression ◽  
Methylguanine Dna Methyltransferase

OBJECTIVEGlutamatergic signaling significantly promotes proliferation, migration, and invasion in glioblastoma (GBM). Riluzole, a metabotropic glutamate receptor 1 inhibitor, reportedly suppresses GBM growth. However, the effects of combining riluzole with the primary GBM chemotherapeutic agent, temozolomide (TMZ), are unknown. This study aimed to investigate the efficacy of combinatorial therapy with TMZ/riluzole for GBM in vitro and in vivo.METHODSThree GBM cell lines, T98G (human; O6-methylguanine DNA methyltransferase [MGMT] positive), U87MG (human; MGMT negative), and GL261 (murine; MGMT positive), were treated with TMZ, riluzole, or a combination of both. The authors performed cell viability assays, followed by isobologram analysis, to evaluate the effects of combinatorial treatment for each GBM cell line. They tested the effect of riluzole on MGMT, a DNA repair enzyme causing chemoresistance to TMZ, through quantitative real-time reverse transcription polymerase chain reaction in T98G cells. Furthermore, they evaluated the efficacy of combinatorial TMZ/riluzole treatment in an orthotopic mouse allograft model of MGMT-positive GBM using C57BL/6 J mice and GL261 cells.RESULTSRiluzole displayed significant time- and dose-dependent growth-inhibitory effects on all GBM cell lines assessed independently. Riluzole enhanced the antitumor effect of TMZ synergistically in MGMT-positive but not in MGMT-negative GBM cell lines. Riluzole singularly suppressed MGMT expression, and it significantly suppressed TMZ-induced MGMT upregulation (p < 0.01). Furthermore, combinatorial TMZ/riluzole treatment significantly suppressed tumor growth in the intracranial MGMT-positive GBM model (p < 0.05).CONCLUSIONSRiluzole attenuates TMZ-induced MGMT upregulation and enhances the antitumor effect of TMZ in MGMT-positive GBMs. Therefore, combinatorial TMZ/riluzole treatment is a potentially promising novel therapeutic regimen for MGMT-positive GBMs.

4-Acetylantrocamol LT3 Inhibits Glioblastoma Cell Growth and Downregulates DNA Repair Enzyme O6-Methylguanine-DNA Methyltransferase

2021 ◽  
pp. 1-17
Author(s):  
Shih-Yu Lee ◽  
I-Chuan Yen ◽  
Jang-Chun Lin ◽  
Min-Chieh Chung ◽  
Wei-Hsiu Liu
Keyword(s):  
Dna Repair ◽  
Cell Viability ◽  
Colony Formation ◽  
Dna Methyltransferase ◽  
Growth Factor Receptor ◽  
Repair Enzyme ◽  
U251 Cell ◽  
Methylguanine Dna Methyltransferase

Glioblastoma multiforme (GBM) is a deadly malignant brain tumor that is resistant to most clinical treatments. Novel therapeutic agents that are effective against GBM are required. Antrodia cinnamomea has shown antiproliferative effects in GBM cells. However, the exact mechanisms and bioactive components remain unclear. Thus, the present study aimed to investigate the effect and mechanism of 4-acetylantrocamol LT3 (4AALT3), a new ubiquinone from Antrodia cinnamomeamycelium, in vitro. U87 and U251 cell lines were treated with the indicated concentration of 4AALT3. Cell viability, cell colony-forming ability, migration, and the expression of proteins in well-known signaling pathways involved in the malignant properties of glioblastoma were then analyzed by CCK-8, colony formation, wound healing, and western blotting assays, respectively. We found that 4AALT3 significantly decreased cell viability, colony formation, and cell migration in both in vitro models. The epidermal growth factor receptor (EGFR), phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR), Hippo/yes-associated protein (YAP), and cAMP-response element binding protein (CREB) pathways were suppressed by 4AALT3. Moreover, 4AALT3 decreased the level of DNA repair enzyme O6-methylguanine-DNA methyltransferase and showed a synergistic effect with temozolomide. Our findings provide the basis for exploring the beneficial effect of 4AALT3 on GBM in vivo.

scholarly journals MGMT genomic rearrangements contribute to chemotherapy resistance in gliomas

2020 ◽  
Author(s):  
Barbara Oldrini ◽  
Nuria Vaquero-Siguero ◽  
Quanhua Mu ◽  
Paula Kroon ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Chemotherapy Resistance ◽  
Glioma Cells ◽  
Promoter Hypermethylation ◽  
Dna Adduct ◽  
Genomic Rearrangements ◽  
Low Grade ◽  
Methylguanine Dna Methyltransferase

AbstractTemozolomide (TMZ) is an oral alkylating agent used for the treatment of glioblastoma and is now becoming a chemotherapeutic option in patients diagnosed with high-risk low-grade gliomas. The O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for the direct repair of the main TMZ-induced toxic DNA adduct, the O6-Methylguanine lesion. MGMT promoter hypermethylation is currently the only known biomarker for TMZ response in glioblastoma patients. Here we show that a subset of recurrent gliomas carries MGMT genomic rearrangements that lead to MGMT overexpression, independently from changes in its promoter methylation. By leveraging the CRISPR/Cas9 technology we generated some of these MGMT rearrangements in glioma cells and demonstrated that the MGMT genomic rearrangements contribute to TMZ resistance both in vitro and in vivo. Lastly, we showed that such fusions can be detected in tumor-derived exosomes and could potentially represent an early detection marker of tumor recurrence in a subset of patients treated with TMZ.

scholarly journals MGMT-activated DUB3 stabilizes MCL1 and drives chemoresistance in ovarian cancer

2019 ◽  
Vol 116 (8) ◽  
pp. 2961-2966 ◽  
Author(s):  
Xiaowei Wu ◽  
Qingyu Luo ◽  
Pengfei Zhao ◽  
Wan Chang ◽  
Yating Wang ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
Dna Methyltransferase ◽  
Essential Role ◽  
Histone Deacetylase Inhibitors ◽  
Combined Treatment ◽  
Ovarian Cancer Cells ◽  
Methylguanine Dna Methyltransferase

Chemoresistance is a severe outcome among patients with ovarian cancer that leads to a poor prognosis. MCL1 is an antiapoptotic member of the BCL-2 family that has been found to play an essential role in advancing chemoresistance and could be a promising target for the treatment of ovarian cancer. Here, we found that deubiquitinating enzyme 3 (DUB3) interacts with and deubiquitinates MCL1 in the cytoplasm of ovarian cancer cells, which protects MCL1 from degradation. Furthermore, we identified that O6-methylguanine-DNA methyltransferase (MGMT) is a key activator of DUB3 transcription, and that the MGMT inhibitor PaTrin-2 effectively suppresses ovarian cancer cells with elevated MGMT-DUB3-MCL1 expression both in vitro and in vivo. Most interestingly, we found that histone deacetylase inhibitors (HDACis) could significantly activate MGMT/DUB3 expression; the combined administration of HDACis and PaTrin-2 led to the ideal therapeutic effect. Altogether, our results revealed the essential role of the MGMT-DUB3-MCL1 axis in the chemoresistance of ovarian cancer and identified that a combined treatment with HDACis and PaTrin-2 is an effective method for overcoming chemoresistance in ovarian cancer.

Novel Neonatal Umbilical Catheter Protection and Stabilization Device in In vitro Model of Catheterized Human Umbilical Cords: Effect of Material and Venting on Bacterial Colonization

2019 ◽  
Author(s):  
Lauren S. Y. Wood ◽  
Janene H. Fuerch ◽  
Carl L. Dambkowski ◽  
Eric F. Chehab ◽  
Shivani Torres ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Bacterial Load ◽  
Standard Of Care ◽  
Adhesive Tape ◽  
Human Umbilical Cord ◽  
Current Standard ◽  
Central Lines ◽  
Umbilical Cords

Abstract Objective Umbilical central lines deliver life-saving medications and nutrition for neonates; however, complications associated with umbilical catheters (UCs) occur more frequently than in adults with central lines (i.e., line migration, systemic infection). We have developed a device for neonatal UC protection and stabilization to reduce catheter exposure to bacteria compared with the standard of care: “goal post” tape configuration. This study analyzes the effect of device venting and material on bacterial load of human umbilical cords in vitro. Study Design Catheters were inserted into human umbilical cord segments in vitro, secured with plastic or silicone vented prototype versus tape, and levels of bacterial colonization were compared between groups after 7 days of incubation. Results Nonvented plastic prototype showed increased bacterial load compared with goal post (p = 0.04). Colonization was comparable between the goal post and all vented plastic prototypes (p ≥ 0.30) and when compared with the vented silicone device (p = 1). Conclusion A novel silicone device does not increase external bacterial colonization compared with the current standard of care for line securement, and may provide a safe, convenient alternative to standard adhesive tape for UC stabilization. Future studies are anticipated to establish safety in vivo, alongside benefits such as migration and infection reduction.

Effect of VAL-083, a novel N7 alkylating agent, on growth of temolozomide-resistant primary adult glioblastoma multiforme (GBM) cells providing a new potential treatment option for GBM.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e13123-e13123
Author(s):  
Sandra E. Dunn ◽  
Kaiji Hu ◽  
Abbas Fotovati ◽  
James Chen ◽  
Joanna Triscott ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Alkylating Agent ◽  
Standard Of Care ◽  
Clinical Activity ◽  
Front Line ◽  
New Agents ◽  
Methylguanine Dna Methyltransferase ◽  
The Usa ◽  
Intrinsic Drug Resistance

e13123 Background: Glioblastoma (GBM) remains one of the most difficult tumors to treat first because many new agents fail to cross the blood brain barrier (BBB), and second due to intrinsic drug resistance. Temozolomide (TMZ) is a front-line therapy for the treatment of GBM; however, it is often ineffective due to drug inactivation by O6-methylguanine-DNA methyltransferase (MGMT). Cancer stem cells (CSC) are a subpopulation of the tumor that resist therapy and give rise to relapse. Here we describe VAL-083, a novel alkylating agent that creates N7 methylation on DNA, and readily crosses the BBB. VAL-083 is currently undergoing human clinical trials in the USA in refractory GBM patients. We previously described how VAL-083 can overcome resistance associated with MGMT in cell lines, and targets brain tumor CSCs. This demonstrates that VAL-083 has the potential to surpass the standard-of-care. Methods: To provide further preclinical support for VAL-083 we examined the effect of VAL-083 on primary adult GBM cells in culture, isolated fresh following surgical resection, in cases where clinical activity of TMZ was known to be limited and high expression of MGMT had been observed. Results: VAL-083 (5uM) inhibited cell growth in these primary adult GBMs that did not show significant sensitivity to TMZ in vitro. VAL-083 also inhibited the growth of CSCs by 100% in neurosphere growth assays. Conclusions: In summary, VAL-083 demonstrates in vitro efficacy against primary adult GBM cells where TMZ has limited activity thereby further supporting the potential of VAL-083 to surpas the standard-of-care.

An innovative cyanoacrylate device developed to improve the current standard of care for intravascular catheter securement

2019 ◽  
Vol 21 (3) ◽  
pp. 293-299
Author(s):  
Amanda Guido ◽  
Sheng Zhang ◽  
Cheng Yang ◽  
Laura Pook
Keyword(s):  
Cost Effective ◽  
Standard Of Care ◽  
Intravascular Catheter ◽  
Current Standard ◽  
Care Protocol ◽  
Intravascular Catheters ◽  
Intravascular Devices ◽  
Strength And Durability

Introduction: Over one billion intravascular devices are used worldwide, annually. Due to the associated complications with these devices, the development of a reliable yet cost-effective securement technique is extremely important. The purpose of this study is to demonstrate the strength of a novel catheter securement cyanoacrylate for securing peripheral venous catheters, central venous catheters, peripherally inserted central catheters, and all other intravascular catheter types. Materials and methods: An unprecedented in vitro method was performed to quantify and compare the strength of a novel cyanoacrylate product when securing intravascular catheters inserted into prepared porcine skin. In vivo, canine subjects were used to implant various types of catheters. These catheters were secured with a novel catheter securement cyanoacrylate to test the strength and durability while undergoing simulated clinical stresses. Results: In vitro, the catheter securement cyanoacrylate demonstrated superior strength over conventional catheter securement methods as well as other known cyanoacrylates. The catheter securement cyanoacrylate demonstrated the ability to maintain superior strength for up to 7 days. In vivo, the catheter securement cyanoacrylate demonstrated the ability to withstand five weight tugs per hour for a 3-h duration, alone, while securing three types of catheters in canine subjects. Conclusion: This is one of the first studies to provide quantitative data to support the use of cyanoacrylate for intravascular catheter securement. The results from this research suggest that the novel catheter securement cyanoacrylate can be a simple and cost-effective catheter securement device that can improve the current health care protocol for intravascular catheterization.

scholarly journals DDRE-25. NOVEL TEMOZOLOMIDE ANALOGS TO IMPROVE ANTI-TUMOR EFFICACY AND OVERCOME RESISTANCE IN GLIOBLASTOMA MULTIFORME

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii66-ii67
Author(s):  
Ariana Waters ◽  
Nozomi Tomimatsu ◽  
Ivan Babic ◽  
Elmar Nurmemmedov ◽  
Annamarie Allnutt ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Acquired Resistance ◽  
Treatment Strategies ◽  
Standard Of Care ◽  
Over Expression ◽  
Methylguanine Dna Methyltransferase ◽  
Incurable Disease ◽  
Anticancer Effects ◽  
Anti Cancer

Abstract Glioblastoma (GBM) is considered one of the most lethal forms of human cancers, and despite considerable advances in multimodality treatments, it remains an incurable disease with an overall survival of 14 to 16 months after diagnosis. Even in the era of personalized medicine and immunotherapy, temozolomide (TMZ), an oral alkylating agent, remains the standard-of-care for GBM. However, intrinisic or acquired resistance to TMZ due to over expression of O6-methylguanine-DNA methyltransferase (MGMT) results in initial treatment inefficacy or tumor relapse, highlighting the significant need for improved treatment strategies. Recently, much effort has been directed towards creating novel TMZ analogs to address the clinical barriers associated with TMZ. While some reported TMZ analogs showed improved brain permeability and anticancer effects in preclinical models, none of them have progressed to testing in humans. There is therefore significant room to improve the brain permeability and anticancer effect profiles of TMZ by incorporating yet unexplored functional groups into new analogs. We have designed and synthesized a series of novel C8-substituted TMZ analogs and have evaluated their anticancer potency against a panel of GBM cell lines with variable levels of MGMT expression. Encouragingly, our analogs demonstrated promising anti-cancer effect in both MGMT low and high expressing lines. We then evaluated our analogs in a variety of cell based assays to compare their activity with TMZ, and performed in vivo brain permeability and anti-tumor efficacy assays in mouse flank models. Our results demonstrated that several of our analogs clearly display improved anti-cancer effects and increased brain permeability over TMZ. This work points to a new direction for the development of novel TMZ analogs for improved patient survival.

scholarly journals Rare Stochastic Expression of O6-Methylguanine- DNA Methyltransferase (MGMT) in MGMT-Negative Melanoma Cells Determines Immediate Emergence of Drug-Resistant Populations upon Treatment with Temozolomide In Vitro and In Vivo

Cancers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 362 ◽  
Author(s):  
Thomas Chen ◽  
Nymph Chan ◽  
Radu Minea ◽  
Hannah Hartman ◽  
Florence Hofman ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Cell Lines ◽  
Melanoma Cell ◽  
Dna Methyltransferase ◽  
Tumor Tissue ◽  
Methylguanine Dna Methyltransferase ◽  
Stochastic Expression ◽  
Melanoma Cell Lines

The chemotherapeutic agent temozolomide (TMZ) kills tumor cells preferentially via alkylation of the O6-position of guanine. However, cells that express the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT), or harbor deficient DNA mismatch repair (MMR) function, are profoundly resistant to this drug. TMZ is in clinical use for melanoma, but objective response rates are low, even when TMZ is combined with O6-benzylguanine (O6BG), a potent MGMT inhibitor. We used in vitro and in vivo models of melanoma to characterize the early events leading to cellular TMZ resistance. Melanoma cell lines were exposed to a single treatment with TMZ, at physiologically relevant concentrations, in the absence or presence of O6BG. Surviving clones and mass cultures were analyzed by Western blot, colony formation assays, and DNA methylation studies. Mice with melanoma xenografts received TMZ treatment, and tumor tissue was analyzed by immunohistochemistry. We found that MGMT-negative melanoma cell cultures, before any drug treatment, already harbored a small fraction of MGMT-positive cells, which survived TMZ treatment and promptly became the dominant cell type within the surviving population. The MGMT-negative status in individual cells was not stable, as clonal selection of MGMT-negative cells again resulted in a mixed population harboring MGMT-positive, TMZ-resistant cells. Blocking the survival advantage of MGMT via the addition of O6BG still resulted in surviving clones, although at much lower frequency and independent of MGMT, and the resistance mechanism of these clones was based on a common lack of expression of MSH6, a key MMR enzyme. TMZ treatment of mice implanted with MGMT-negative melanoma cells resulted in effective tumor growth delay, but eventually tumor growth resumed, with tumor tissue having become MGMT positive. Altogether, these data reveal stochastic expression of MGMT as a pre-existing, key determinant of TMZ resistance in melanoma cell lines. Although MGMT activity can effectively be eliminated by pharmacologic intervention with O6BG, additional layers of TMZ resistance, although considerably rarer, are present as well and minimize the cytotoxic impact of TMZ/O6BG combination treatment. Our results provide rational explanations regarding clinical observations, where the TMZ/O6BG regimen has yielded mostly disappointing outcomes in melanoma patients.

scholarly journals Patient-Derived Glioma Models: From Patients to Dish to Animals

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1177 ◽  
Author(s):  
Cintia Carla da Hora ◽  
Markus W. Schweiger ◽  
Thomas Wurdinger ◽  
Bakhos A. Tannous
Keyword(s):  
Standard Of Care ◽  
Primary Brain Tumor ◽  
Tumor Formation ◽  
Current Standard ◽  
Clinical Phase ◽  
Current State ◽  
Established Cell ◽  
Representative Model

Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults associated with a poor survival. Current standard of care consists of surgical resection followed by radiation and chemotherapy. GBMs are highly heterogeneous, having a complex interaction among different cells within the tumor as well as the tumor microenvironment. One of the main challenges in the neuro-oncology field in general, and GBM in particular, is to find an optimum culture condition that maintains the molecular genotype and phenotype as well as heterogeneity of the original tumor in vitro and in vivo. Established cell lines were shown to be a poor model of the disease, failing to recapitulate the phenotype and harboring non-parental genotypic mutations. Given the growing understanding of GBM biology, the discovery of glioma cancer stem-like cells (GSCs), and their role in tumor formation and therapeutic resistance, scientists are turning more towards patient-derived cells and xenografts as a more representative model. In this review, we will discuss the current state of patient-derived GSCs and their xenografts; and provide an overview of different established models to study GBM biology and to identify novel therapeutics in the pre-clinical phase.

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