scholarly journals Role of O6-methylguanine-DNA methyltransferase and p53 in response of neuroblastoma cells to an alkylating agent temozolomide

2018 ◽  
Vol 99 (1) ◽  
pp. 47-53
Author(s):  
R R Khusnutdinov ◽  
S V Boychuk
Keyword(s):  
Dna Methyltransferase ◽  
Alkylating Agent ◽  
Neuroblastoma Cells ◽  
Methylguanine Dna Methyltransferase

Цель. Изучить роль белка р53 и О6-метилгуанин-ДНК-метилтрансферазы в чувствительности клеток нейробластомы к действию темозоломида. Методы. Исследование проводили на клеточной линии нейробластомы SK.N.SH, культивируемой в среде DMEM с добавлением эмбриональной телячьей сыворотки и антибиотиков пенициллина-стрептомицина в стандартных условиях (37 °C и 5% СО2). Клетки инкубировали с алкилирующим агентом темозоломидом в течение 48-72 ч. В ряде случаев осуществляли преинкубацию клеток в течение 2 ч с О6-бензилгуанином (ингибитором О6-метилгуанин-ДНК-метилтрансферазы) или нутлином-3а (реактиватором р53). Пролиферативную активность оценивали с помощью системы многопараметрического анализа клеточных культур (RTCA iCELLigence), а также колориметрического MTS-теста. Экспрессию белков определяли методом иммуноблоттинга с использованием соответствующих моноклональных антител. Результаты. Реактивация белка р53 приводила к значительному снижению скорости пролиферации клеток линии SK.N.SH. Цитотоксический эффект данного препарата более выражен по сравнению с темозоломидом, считающимся препаратом выбора при проведении химиотерапии пациентам с мультиформной глиобластомой и нейробластомой. Ингибирование О6-метилгуанин-ДНК-метилтрансферазы также приводило к усилению цитотоксического эффекта темозоломида, тем не менее, цитотоксический эффект химиопрепарата был менее выраженным по сравнению с действием темозоломида на фоне реактивации белка р53. Вывод. Для оценки чувствительности клеток нейробластомы к действию алкилирующего препарата темозоломида функциональное состояние белка р53 в опухолевых клетках служит более важным прогностическим критерием по сравнению с уровнем экспрессии О6-метилгуанин-ДНК-метилтрансферазы; кроме того, реактивация белка р53 приводит к снижению скорости пролиферации клеток нейробластомы линии SK.N.SH и их гибели по механизму апоптоза.

scholarly journals Role of O6-methylguanine-DNA methyltransferase in protecting from alkylating agent-induced toxicity and mutations in mice

2006 ◽  
Vol 28 (5) ◽  
pp. 1111-1116 ◽  
Author(s):  
R. J. Hansen ◽  
R. Nagasubramanian ◽  
S. M. Delaney ◽  
L. D. Samson ◽  
M.E. Dolan
Keyword(s):  
Dna Methyltransferase ◽  
Alkylating Agent ◽  
Methylguanine Dna Methyltransferase

The Role of O6-Methylguanine-DNA Methyltransferase in a Long-Surviving Metastatic Melanoma

2014 ◽  
Vol 18 (1) ◽  
pp. 60-62 ◽  
Author(s):  
Alessandro Gatti ◽  
Nicola di Meo ◽  
Giuseppe Stinco ◽  
Maria Malagoli ◽  
Serena Bonin ◽  
...  
Keyword(s):  
Metastatic Melanoma ◽  
Poor Prognosis ◽  
Dna Methyltransferase ◽  
Alkylating Agent ◽  
Methylation Status ◽  
Chemotherapeutic Agents ◽  
Methylguanine Dna Methyltransferase ◽  
Clinical Control ◽  
Resistance To Chemotherapy

Background: Brain metastases commonly occur in patients with metastatic melanoma and are associated with a poor prognosis. Only a few chemotherapeutic agents have been shown to be potentially active. Resistance to chemotherapy is one of the main limitations to treatment. A key mechanism of resistance is O6-methylguanine-DNA methyltransferase (MGMT). The methylation of its promotor could inhibit the activity of this enzyme; consequently, it is very important to evaluate the methylation status of all available specimens. Case Report: We report the case of a long-surviving patient in whom combination treatment with an alkylating agent inhibiting MGMT, such as temozolomide, was useful in clinical control of the disease.

scholarly journals Impact of Temozolomide on Immune Response during Malignant Glioma Chemotherapy

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Sadhak Sengupta ◽  
Jaclyn Marrinan ◽  
Caroline Frishman ◽  
Prakash Sampath
Keyword(s):  
Immune Response ◽  
Malignant Glioma ◽  
Dna Methyltransferase ◽  
Opportunistic Infections ◽  
Immune Surveillance ◽  
Drug Resistant ◽  
Methylguanine Dna Methyltransferase ◽  
Drug Resistant Mutation ◽  
Resistant Mutation

Malignant glioma, or glioblastoma, is the most common and lethal form of brain tumor with a median survival time of 15 months. The established therapeutic regimen includes a tripartite therapy of surgical resection followed by radiation and temozolomide (TMZ) chemotherapy, concurrently with radiation and then as an adjuvant. TMZ, a DNA alkylating agent, is the most successful antiglioma drug and has added several months to the life expectancy of malignant glioma patients. However, TMZ is also responsible for inducing lymphopenia and myelosuppression in malignant glioma patients undergoing chemotherapy. Although TMZ-induced lymphopenia has been attributed to facilitate antitumor vaccination studies by inducing passive immune response, in general lymphopenic conditions have been associated with poor immune surveillance leading to opportunistic infections in glioma patients, as well as disrupting active antiglioma immune response by depleting both T and NK cells. Deletion of O6-methylguanine-DNA-methyltransferase (MGMT) activity, a DNA repair enzyme, by temozolomide has been determined to be the cause of lymphopenia. Drug-resistant mutation of the MGMT protein has been shown to render chemoprotection against TMZ. The immune modulating role of TMZ during glioma chemotherapy and possible mechanisms to establish a strong TMZ-resistant immune response have been discussed.

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.

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