Sensitivity of transplantable melanoma cells to cytokines with regard to their spontaneous apoptosis.

Objectives: Changes in the sensitivity of two lines of transplantable melanoma cells to the antiproliferative activity of interleukin 6 (IL-6), oncostatin M (OSM), tumor necrosis factor-alpha (TNF-alpha) during melanoma progression were the subject of this study. We were looking for a correlation between these changes and the ability of melanoma cells to undergo spontaneous apoptosis.

Methods: The influence of exogenous cytokines on the proliferation of melanoma cells was measured by colorimetric methods with MTT and apoptosis of these cells was estimated by staining with annexin V/propidium iodide, measurement of DNA degradation and cell cycle analysis.

Results: It was observed that during melanoma progression the sensitivity of those two melanoma line cells to the antiproliferative effect of IL-6 and OSM did not change, while a spontaneous alteration of the melanotic line into an amelanotic one seemed to be accompanied by resistance of the amelanotic melanoma cells to the antiproliferative activity of TNF-alpha. Simultaneously, we observed a decreased ability of amelanotic melanoma cells (in comparison with the native line) to undergo spontaneous apoptosis.

Conclusions: The observed resistance to the TNF-alpha antiproliferative effect which appears during melanoma progression seems to be correlated with a lower ability of the amelanotic melanoma cells to undergo spontaneous apoptosis.