Acute and Long-Term Effects of Hyperthermia in B16-F10 Melanoma Cells

OBJECTIVE: Hyperthermia uses exogenous heat induction as a cancer therapy. This work addresses the acute and long-term effects of hyperthermia in the highly metastatic melanoma cell line B16-F10. MATERIALS AND METHODS: Melanoma cells were submitted to one heat treatment, 45°C for 30 min, and thereafter were kept at 37°C for an additional period of 14 days. Cultures maintained at 37°C were used as control. Cultures were assessed for the heat shock reaction. RESULTS: Immediately after the heat shock, cells began a process of fast degradation, and, in the first 24 h, cultures showed decreased viability, alterations in cell morphology and F-actin cytoskeleton organization, significant reduction in the number of adherent cells, most of them in a process of late apoptosis, and an altered gene expression profile. A follow-up of two weeks after heat exposure showed that viability and number of adherent cells remained very low, with a high percentage of early apoptotic cells. Still, heat-treated cultures maintained a low but relatively constant population of cells in S and G(2)/M phases for a long period after heat exposure, evidencing the presence of metabolically active cells. CONCLUSION: The melanoma cell line B16-F10 is susceptible to one hyperthermia treatment at 45°C, with significant induced acute and long-term effects. However, a low but apparently stable percentage of metabolically active cells survived long after heat exposure

Processo de fabrico, estrutura e propriedades de compósitos ferro-vidro obtidos por redução directa de concentrados de magnetite

Dissertação apresentada para obtenção do grau de Doutor em Engenharia Metalúrgica, na Faculdade de Engenharia da Universidade do Port

Apoptosis assessment of B16-F10 melanoma cells submitted to a heat treatment (HT), 45°C for 30 min.

<p>Representative histograms (from four independent experiments), before the heat treatment (d 0) and after, at defined time-points (d 0, 0 h–d 14, immediately to 14 days after heat exposure). Flow cytometry analysis of Annexin-FITC/PI uptake (A, necrosis; B, late apoptosis; C, viable cells; D, early apoptosis).</p

Apoptosis assessment of B16-F10 melanoma cells submitted to a heat treatment (HT), 45°C for 30 min.

<p>Flow cytometry analysis of Annexin-FITC/PI uptake to evaluate the percentage of cells in early and late apoptosis. Following the heat treatment, cultures were maintained at 37°C for 2 weeks. A: control cultures (kept at 37°C during the culture time); B: heat-treated cultures; C: detail of the heat-treated cultures during the first 24 h after heat exposure. *Significantly different from control (cultures kept at 37°C).</p

Primers used on RT-PCR analysis.

<p>Primers used on RT-PCR analysis.</p

Number of adherent cells/cm² in control and heat-treated cultures throughout the culture period, at defined time-points.

<p>Number of adherent cells/cm² in control and heat-treated cultures throughout the culture period, at defined time-points.</p

Cell viability/proliferation of B16-F10 melanoma cells submitted to a heat treatment (HT), 45°C for 30 min.

<p>Cultures were heated at day 5 (Arrow) and further maintained at 37°C for 2 weeks. A: MTT assay, throughout the culture period; B: Detail of the MTT assay during the first 24 h after the heat treatment; C: LDH assay during the first 24 h after the heat treatment. *Significantly different from control (cultures kept at 37°C).</p