Antitumor effect of sarcnu in a 06-methylguanine-DNA methyltransferase positive human glioma xenograft model

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.

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1702736114 ◽

2017 ◽

Vol 114 (16) ◽

pp. 4129-4134 ◽

Cited By ~ 20

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.

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Expression of O6-methylguanine-DNA methyltransferase in malignant human glioma cell lines

Carcinogenesis ◽

10.1093/carcin/12.9.1739 ◽

1991 ◽

Vol 12 (9) ◽

pp. 1739-1744 ◽

Cited By ~ 20

Author(s):

Lawrence E. Ostrowski ◽

Mathew A. von Wronski ◽

Sandra H. Bigner ◽

Ahmed Rasheed ◽

S.Clifford Schold ◽

...

Keyword(s):

Cell Lines ◽

Glioma Cell ◽

Dna Methyltransferase ◽

Human Glioma ◽

Human Glioma Cell ◽

Methylguanine Dna Methyltransferase ◽

Glioma Cell Lines

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Vemurafenib Sensitizes Melanoma Cells to Temozolomide by Downregulating MGMT Expression.

10.21203/rs.3.rs-83301/v1 ◽

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.

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Abstract A225: The mTOR kinase inhibitor AZD8055 modulates18F‐FDG uptakein vivoin the human glioma xenograft model U87‐MG

10.1158/1535-7163.targ-09-a225 ◽

2009 ◽

Cited By ~ 1

Author(s):

Heather Keen ◽

Sally‐Ann Ricketts ◽

Juliana Bales ◽

Aoife Shannon ◽

Armelle Logie ◽

...

Keyword(s):

Kinase Inhibitor ◽

Xenograft Model ◽

Human Glioma ◽

Mtor Kinase ◽

Glioma Xenograft

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Antitumor effect of levetiracetam combined with temozolomide in glioma cell lines.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e13530 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e13530-e13530

Author(s):

Zhong-ping Chen ◽

Qing-wu Wu ◽

Jing Wang

Keyword(s):

Cell Proliferation ◽

Cell Lines ◽

Glioma Cell ◽

Dna Methyltransferase ◽

Antitumor Effect ◽

Inhibitory Concentration ◽

Cell Counting ◽

Methylguanine Dna Methyltransferase ◽

Negative Cell ◽

Glioma Cell Lines

e13530 Background: The antitumor effect oftemozolomide (TMZ) is still remitted for portion of glioma patients, and if anti-epilepcy drug levetiracetam (LEV) may help TMZ for anti-glioma is not clear. Methods: The cell proliferation with Cell Counting Kit-8 (CCK-8) assay was performed in two O6-methylguanine DNA methyltransferase (MGMT) positive cell lines (T98G and U138) and two other MGMT negative cell lines (SKMG-4 and U87). The cells were treated with LEV and TMZ alone or in combination. Results: LEV inhibited the proliferation of glioma cell lines but not reach therapeutic effect, especially in U87cell line. The 50% inhibitory concentration (IC50) of TMZ was significantly decreased in cell lines (T98G, U138 and SKMG-4, P< 0.05) which were treated with TMZ and LEV, but no significantly changed in U87 (P> 0.05). Conclusions: LEV may inhibit the proliferation of glioma cell lines (both MGMT- positive and MGMT-negative) and also sensitizes cell lines (T98G, U138 and SKMG-4, but not U87) to TMZ.

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