Evaluation of the cytotoxicity of hyperthermia, chemotherapy and their combined effects in human melanoma cells

• Autor(a) principal: Salvador, Diana Serenela Andrade
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/33327
• topic: Skin cancer; Hyperthermia; Dacarbazine; Doxorubicin; Antitumor potential

Melanoma is the most severe type of skin cancer, and its incidence is estimated to increase at an alarming rate. Due to its heterogeneity and drug resistance, treatment is challenging, and options are scarce when diagnosis occurs at an advanced stage. For this reason, there has been a demand for new therapeutic approaches. Hyperthermia works by raising the temperature of the tumor to a temperature between 40°C and 45°C, resulting in cell death. Despite the benefits when used as a single therapy, it is most commonly used in combination with other therapies, of which chemotherapy stands out. Thus, the aim of this study was to analyse the effectiveness of hyperthermia in combination with two chemotherapeutic agents, dacarbazine (DTIC) and doxorubicin (DOX), in the treatment of melanoma cells and to determine the associated mechanisms. In chapter 1, the problem of melanoma cases and their treatment was highlighted, as well as the potential of the therapies in separate or combined. In chapter 2, the effect of temperatures between 40 ºC and 45 ºC on the cell viability of human melanoma lines A375 and MNT-1 was evaluated. The lower temperature was shown to have a reduced impact on cell viability, while the higher temperature caused cell death rates >90%. Thereafter, exposure to DTIC at concentrations ranging from 6.25 to 500 μg/mL was shown to decrease cell viability in a concentration- and time-dependent manner. Treatment with hyperthermia in combination with DTIC revealed a potentiating effect, but this appeared to be dependent on the concentration of DTIC and the period of hyperthermia. Additionally, treatment with DTIC at concentrations corresponding to the IC20 of 48 hours of exposure and 43°C for 30 minutes caused a delay in the cell cycle in the G2/M phase of the A375 cells and in the S and G2/M phases of MNT-1 cells. An increased production of reactive oxygen species in both cell lines and apoptosis in A375 cells was also observed, caused by hyperthermia. In chapter 3, treatment with DOX at concentrations between 0.001 and 10 μM was shown to be more effective in A375 cells, being dependent on the concentration and time of exposure in both cell lines. Hyperthermia increased the effectiveness of DOX, but only at certain concentrations and exposure times tested. Treatment with DOX and hyperthermia showed to delay the cell cycle at the G2/M phase, as well as increased the levels of reactive oxygen species compared to separate treatments in both cell lines. Combined treatment also increased the number of apoptotic MNT-1 cells, while A375 cells responded similarly to treatment with only hyperthermia. In summary, this dissertation supports that simultaneous hyperthermia and chemotherapy treatment show promising results in the treatment of melanoma.