AZT on telomerase activity and cell proliferation in HS 839.T melanoma cells / AZT na atividade da telomerase e na proliferação de células de melanoma HS 839.T

PURPOSE: To evaluate telomerase activity and proliferation of HS839.T melanoma cells, subjected to the action of AZT. METHODS: Cells were grown in triplicate, AZT at different concentrations: 50, 100 and 200μM, was added and left for 24 and 48 hours, and its effects were compared with the control group. Telomerase activity was detected by PCR and cell proliferation was evaluated by MTT. RESULTS: After 24 hours, there was no inhibition of cell proliferation or telomerase activity when compared to the control group. After 48 hours, there was a momentary decrease, suggesting that the cell lines used in this study are sensitive to AZT, but quickly recover both the enzyme activity and cell proliferation. CONCLUSION: The action of AZT on the melanoma cells studied, at the concentrations and times tested, did not inhibit telomerase activity nor affect cell proliferation.

OBJETIVO: Avaliar a atividade da telomerase e da proliferação de células de melanoma HS839.T submetidas à ação do AZT. MÉTODOS: As células foram cultivadas, em triplicata, com diferentes concentrações de AZT: 50, 100 e 200µM, por 24h e 48h, seus efeitos comparados com o grupo controle. A atividade da telomerase foi detectada por PCR e a proliferação celular avaliada por MTT. RESULTADOS: No tempo de 24 horas, não houve inibição da proliferação celular e da atividade da telomerase em comparação com o grupo controle. No período de 48 horas, houve uma diminuição momentânea, sugerindo que as células das linhagens utilizadas neste estudo são sensíveis ao AZT, mas que recuperam a atividade enzimática e proliferativa. CONCLUSÃO: Nas células de melanoma HS839.T estudadas e nas concentrações e tempos propostos, a ação do AZT não inibiu a atividade da telomerase e não afetou a proliferação celular.

Isolated limb perfusion with hyperthermia and chemotherapy: predictive factors for regional toxicity

OBJECTIVE: Isolated limb perfusion combined with melphalan is an accepted treatment for obtaining locoregional control in advanced melanoma of the extremities and other malignant neoplasias restricted to the limb. This study aims to examine the factors associated with toxicity caused by the regional method. We considered the technical aspects of severe complications associated with the procedure in an attempt to diminish the patient morbidity that occurs during the learning curve. METHODS: We conducted a retrospective analysis of the records of patients who underwent perfusion at the AC Camargo Hospital in São Paulo, Brazil between January 2000 and January 2009. The Wieberdink scale was applied to classify local toxicity and its relation to clinical and laboratory variables. RESULTS: Fifty-eight perfusions were performed in 55 patients. Most patients (86.2%) presented a toxicity level between I and III. Grade V toxicity was seen in five cases (8.6%), four of which occurred in the first 2 years. Creatine phosphokinase, an important predictive factor for toxicity, had an average value of 231.8 for toxicity grades I-III and 1286.2 for toxicity grades IV-V (p = 0.001). There was a relationship between the melphalan dose and toxicity, which was 77 mg (25 to 130 mg) for toxicity grades I-II and 93.5 mg (45 to 120 mg) for toxicity grades IV-V (p = 0.0204). CONCLUSION: It is possible to prevent the toxicity associated with melphalan by adjusting the dose according to the patient's body weight (especially for women and obese patients) and the creatine phosphokinase values in the postoperative period.

Sphingosine 1-Phosphate Triggers Apoptotic Signal for B16 Melanoma Cells via ERK and Caspase Activation

The bioactive sphingolipid metabolite sphingosine 1-phosphate (S1P), recently was reported to induce apoptosis of some cancer cells and neurons, although it generally known to exert mitogenic and antiapoptotic effects. In this study, we investigated the effects of S1P on the cell growth, melanogenesis, and apoptosis of cultured B16 mouse melanoma cells. In results, S1P was found to induce apoptosis in B16 melanoma cells in a dose- and time-dependent manner, but exerted minimal effects on melanogenesis. Although receptors of sphingosine 1-phosphate (endothelial differentiation gene 1 [Edg]/S1P1, Edg5/S1P2, Edg3/S1P3) were expressed in B16 melanoma cells, they were shown not to be associated with S1P-induced apoptosis. In addition, pertussis toxin did not block the apoptotic effects of S1P on B16 melanoma cells. S1P induced caspase-3 activation and the extracellular signal-regulated kinase (ERK) activation. Interestingly, the ERK pathway inhibitor, UO126, reversed the apoptotic effects of S1P on B16 melanoma cells. These results suggest that S1P induced apoptosis of B16 melanoma cells via an Edg receptor-independent, pertussis toxin-insensitive pathway, and appears to be associated with the ERK and caspase-3 activation.