| D. Ciências da Saúde - 5. Farmácia - 6. Farmácia |
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involvement of Glutathione IN THE INHIBITION OF multidrug resistance protein Activity BY nitric oxide in murine LYMPHOBLASTIC cell line |
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| Mirela Machado Hangai 1 |
| Tânia Beatriz Creczynski-Pasa 2 |
| Maria Cláudia Santos-Silva 3 |
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| (1. Departamento de Ciências Farmacêuticas, UFSC; 2. Departamento de Ciências Farmacêuticas, UFSC; 3. Departamento de Análises Clínicas, UFSC) |
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| INTRODUÇÃO: |
The acquisition of resistance to anticancer agents used in chemotherapy is the main cause of treatment failure in malignant disorders and identifying the mechanisms leading multidrug resistance (MDR) is important in developing more effective therapies. Several reports show that drug resistance-associated proteins, such as MRP1 and MRP2 extrude chemotherapy drugs out of cells when conjugated to glutathione (GSH). Although, the exact mechanism of MRP involved multidrug resistance remains unknown. GSH is one of the intracellular targets for nitric oxide (NO). NO is an endogenous mediator involved in a variety of cellular regulatory functions including vasodilation, neurotransmission/neuromodulation to cytotoxic activity. One of the NO mechanisms of action is to deplete the intracellular levels of glutathione (GSH), an important endogenous antioxidant, reducing the therapeutic action of some chemoterapic compounds. We have demonstrated the involvement of GSH in NO-induced cytotoxicity on leukemia cells. NO induced a depletion of GSH levels, what was potentialized by L-buthionine-S,R-sulfoximine (BSO), an inhibitor of g-GCS. In this study, we investigated the involvement of NO in the presence or absence of BSO on MRP1 activity in L-1210 leukemia cells. |
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| METODOLOGIA: |
L-1210 cells were incubated with NO donor (SNAP 0,1-1 mM) and BSO (0,01-0,1 mM). The activity of MRP1 was evaluated by incubation of the cells in the absence or presence of fluorescent probe carboxy-5’-6’-dichlorofluorescein diacetate (CFDA, 4 µM) and a MRP inhibitor (probenecid, 1-10 mM). The fluorescence was measured by flow cytometry, to determine the dye extrusion. |
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| RESULTADOS: |
L-1210 cells almost did not retain CFDA intracellularly and probenecid decreased MRP1 activity in a concentration-dependent manner. SNAP and BSO increased the accumulation of CFDA in a concentration-dependent manner. In addition, co-incubation of SNAP with BSO increased the accumulation of fluorescent substrate. The synergic effect observed on CFDA accumulation after the association of BSO 100 µM and SNAP 1 mM was higher than the effect of the association of BSO 10 µM and SNAP 1 mM. |
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| CONCLUSÕES: |
Our results suggest that NO can indirectly interfere in the activity of MRP1 through the depletion of GSH levels. |
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Instituição de fomento: Supported by CAPES and CNPq
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Palavras-chave: Multidrug resistance protein 1; Nitric oxide; L1210 leukemia cells. |
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| Anais da 58ª Reunião Anual da SBPC - Florianópolis, SC - Julho/2006 |