scholarly journals Vemurafenib Sensitizes Melanoma Cells to Temozolomide by Downregulating MGMT Expression.

2020 ◽  
Author(s):  
Bingjie Ren ◽  
Qiang Li ◽  
Jing Zhao ◽  
Xia Guo ◽  
Yingxi Hu ◽  
...  
Keyword(s):  
Malignant Melanoma ◽  
Protein Expression ◽  
Dna Methyltransferase ◽  
Kinase Inhibitor ◽  
Mrna Level ◽  
Xenograft Model ◽  
Mgmt Gene ◽  
Methylguanine Dna Methyltransferase ◽  
Erk Activity

Abstract BackgroundThe alkylating agent temozolomide (TMZ) is widely used to treat melanoma in clinical practice. However, cells expressing the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) are highly resistant to this drug. Vemurafenib (vMF), a targeted BRAF kinase inhibitor, is applied to treat BRAF-V600 mutant metastatic melanoma. Studies have suggested that blocking this pathway prevents MGMT from affecting TMZ sensitization. However, reports of the use of the combination of vMF and TMZ in the treatment of melanoma are lacking.MethodsCell viability was detected by MTT assay, cell apoptosis was assayed by flow cytometry, and the mRNA level of the MGMT gene was measured by RT-qPCR. Western blotting, immunofluorescence staining were utilized to determine the expression of the protein. The pcDNA3.1-MGMT vector was transiently transfected to generate MGMT-overexpressing cells for experiments. A nude mouse malignant melanoma xenograft model was established for in vivo drug experiments.ResultsvMF increased TMZ-induced cytotoxicity by increasing DNA damage. vMF inhibited the MAPK/ERK signaling pathway and the mRNA and protein expression of the MGMT gene. vMF did not inhibit MGMT protein expression in A375-MGMT OE cells, and the vMF-induced sensitization effect was attenuated. Moreover, TMZ exposure activated ERK activity in malignant melanoma. The expression of MGMT and p-ERK1/2 was positively correlated in melanoma tissues.ConclusionvMF sensitized melanoma to TMZ by inhibiting the MAPK/ERK-MGMT pathway, and the combination of vMF and TMZ is expected to improve the clinical treatment effect on malignant melanoma.

scholarly journals Dual bioluminescence and near-infrared fluorescence monitoring to evaluate spherical nucleic acid nanoconjugate activity in vivo

2017 ◽  
Vol 114 (16) ◽  
pp. 4129-4134 ◽  
Author(s):  
Timothy L. Sita ◽  
Fotini M. Kouri ◽  
Lisa A. Hurley ◽  
Timothy J. Merkel ◽  
Alexandra Chalastanis ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Xenograft Model ◽  
Methylguanine Dna Methyltransferase ◽  
Treatment Regimens ◽  
Optical Reporters ◽  
Spherical Nucleic Acids

RNA interference (RNAi)-based gene regulation platforms have shown promise as a novel class of therapeutics for the precision treatment of cancer. Techniques in preclinical evaluation of RNAi-based nanoconjugates have yet to allow for optimization of their gene regulatory activity. We have developed spherical nucleic acids (SNAs) as a blood–brain barrier-/blood–tumor barrier-penetrating nanoconjugate to deliver small interfering (si) and micro (mi)RNAs to intracranial glioblastoma (GBM) tumor sites. To identify high-activity SNA conjugates and to determine optimal SNA treatment regimens, we developed a reporter xenograft model to evaluate SNA efficacy in vivo. Engrafted tumors stably coexpress optical reporters for luciferase and a near-infrared (NIR) fluorescent protein (iRFP670), with the latter fused to the DNA repair protein O6-methylguanine-DNA-methyltransferase (MGMT). Using noninvasive imaging of animal subjects bearing reporter-modified intracranial xenografts, we quantitatively assessed MGMT knockdown by SNAs composed of MGMT-targeting siRNA duplexes (siMGMT-SNAs). We show that systemic administration of siMGMT-SNAs via single tail vein injection is capable of robust intratumoral MGMT protein knockdown in vivo, with persistent and SNA dose-dependent MGMT silencing confirmed by Western blotting of tumor tissue ex vivo. Analyses of SNA biodistribution and pharmacokinetics revealed rapid intratumoral uptake and significant intratumoral retention that increased the antitumor activity of coadministered temozolomide (TMZ). Our study demonstrates that dual noninvasive bioluminescence and NIR fluorescence imaging of cancer xenograft models represents a powerful in vivo strategy to identify RNAi-based nanotherapeutics with potent gene silencing activity and will inform additional preclinical and clinical investigations of these constructs.

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 Identification of Hsp90 inhibitors as potential drugs for the treatment of TSC1/TSC2 deficient cancer

2021 ◽  
Author(s):  
Evelyn M. Mrozek ◽  
Vineeta Bajaj ◽  
Yanan Guo ◽  
Izabela Malinowska ◽  
Jianming Zhang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Xenograft Model ◽  
Growth Delay ◽  
Hsp90 Inhibitors ◽  
Null Cell ◽  
Standard Dosage

Inactivating mutations in either TSC1 or TSC2 cause Tuberous Sclerosis Complex, an autosomal dominant disorder, characterized by multi-system tumor and hamartoma development. Mutation and loss of function of TSC1 and/or TSC2 also occur in a variety of sporadic cancers, and rapamycin and related drugs show highly variable treatment benefit in patients with such cancers. The TSC1 and TSC2 proteins function in a complex that inhibits mTORC1, a key regulator of cell growth, which acts to enhance anabolic biosynthetic pathways. In this study, we identified and validated five cancer cell lines with TSC1 or TSC2 mutations and performed a kinase inhibitor drug screen with 197 compounds. The five cell lines were sensitive to several mTOR inhibitors, and cell cycle kinase and HSP90 kinase inhibitors. The IC50 for Torin1 and INK128, both mTOR kinase inhibitors, was significantly increased in three TSC2 null cell lines in which TSC2 expression was restored.  Rapamycin was significantly more effective than either INK128 or ganetespib (an HSP90 inhibitor) in reducing the growth of TSC2 null SNU-398 cells in a xenograft model. Combination ganetespib-rapamycin showed no significant enhancement of growth suppression over rapamycin. Hence, although HSP90 inhibitors show strong inhibition of TSC1/TSC2 null cell line growth in vitro, ganetespib showed little benefit at standard dosage in vivo. In contrast, rapamycin which showed very modest growth inhibition in vitro was the best agent for in vivo treatment, but did not cause tumor regression, only growth delay.

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.

Effect of Auraptene on angiogenesis in Xenograft model of breast cancer

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohammad Reza Shiran ◽  
Elham Mahmoudian ◽  
Abolghasem Ajami ◽  
Seyed Mostafa Hosseini ◽  
Ayjamal Khojasteh ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gene Expression ◽  
Animal Model ◽  
Protein Expression ◽  
Western Blot ◽  
Xenograft Model ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Abstract Objectives Angiogenesis is the most important challenge in breast cancer treatment. Recently, scientists become interesting in rare natural products and intensive researches was performed to identify their pharmacological profile. Auraptene shows helpful effects such as cancer chemo-preventive, anti-inflammatory, anti-oxidant, immuno-modulatory. In this regard, we investigated the anti-angiogenesis effect of Auraptene in in-vitro and in-vivo model of breast cancer. Methods In this study, 4T, MDA-MB-231 and HUVEC cell lines were used. The proliferation study was done by MTT assay. For tube formation assay, 250 matrigel, 1 × 104 HUVEC treated with Auraptene, 20 ng/mL EGF, 20 ng/mL bFGF and 20 ng/mL VEGF were used. Gene expression of important gene related to angiogenesis in animal model of breast cancer was investigated by Real-time PCR. Protein expression of VCAM-1 and TNFR-1 gene related to angiogenesis in animal model of breast cancer was investigated by western-blot. Results Auraptene treatment led to reduction in cell viability of MDA-MB-231 in a concentration-dependent manner. Also, we observed change in the number of tubes or branches formed by cells incubated with 40 and 80 μM Auraptene. Auraptene effect the gene expression of important gene related to angiogenesis (VEGF, VEGFR2, COX2, IFNɣ). Moreover, the western blot data exhibited that Auraptene effect the protein expression of VCAM-1 and TNFR-1. Conclusions Overall, this study shows that Auraptene significantly suppressed angiogenesis via down-regulation of VEGF, VEGFR2, VCAM-1, TNFR-1, COX-2 and up-regulation of IFNγ.

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