Sensitivity of Transplantable Melanoma Cells to Cytokines with Regard to Their Spontaneous Apoptosis

Abstract

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-α (TNF-α) 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-α. 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-α antiproliferative effect which appears during melanoma progression seems to be correlated with a lower ability of the amelanotic melanoma cells to undergo spontaneous apoptosis.

The activity of caspases in spontaneous and camptothecin-induced death of melanotic and amelanotic melanoma cell

“…These results, taken together with the threefold higher activity of caspase-3 19 and lower ability to undergo spontaneous apoptosis in amelanotic melanoma cells observed in our earlier works, 18,19 may indicate that the cells of this line have mechanism(s) inhibiting activated caspases, e.g., some proteins from IAP family, as suggested by other authors for human melanoma cells. 26 Our earlier findings, where over fourfold fewer cells of amelanotic melanoma line from S/G 2 /M phases died spontaneously, in comparison to melanotic melanoma line, suggest that proliferating amelanotic melanoma cells, in particular, have mechanism(s) protecting them from apoptosis.…”

“…The loss of pigment was accompanied by changes in many biological features of the amelanotic melanoma line-faster tumor growth rate, shorter animal survival and changes in ultrastructure of cells. 9,18 Once established, these melanomas possessed a considerable degree of phenotypic stability over decades of passaging. 9 Since their discovery, each melanoma line is maintained in vivo by consecutive, subcutaneous transplantations of tumor material every 21 (Ma) or 11 (Ab) days.…”

“…[14][15][16][17] Our earlier works showed differences in the ability to undergo spontaneous and camptothecin (CPT)-induced apoptosis between hamster melanotic and amelanotic melanoma cells. 18,19 Based on the observation that cells of the amelanotic melanoma line with a lower capacity to undergo spontaneous apoptosis have a higher activity of caspase-3 than cells of the native melanotic melanoma line, we presumed that caspase-3 did not participate in amelanotic melanoma cell death. 19 The aim of the present study was to elucidate this apparent contradiction by finding if there was any relationship between the proportion of cells with activated caspases and the observed changes of the biological features during the progression of melanotic melanoma into amelanotic melanoma line.…”

Heterogeneous Susceptibility to Spontaneous and Induced Apoptosis Characterizes Two Related Transplantable Melanomas with Different Biological Properties

“…Susceptibility of melanoma cells to apoptosis may be related to their ability to synthesize NO; recently, it was shown that inhibition of NO synthesis induces apoptosis in melanoma cells (31). Our earlier results demonstrated that Ab are able to synthesize NO more vigorously than the Ma line; thus it is possible that endogenous NO is promoting survival of the Ab cells (32). However, these observations do not explain increased activity of caspase‐3 in the same cell line especially since NO is reported to inhibit caspases in other cell systems, thus decreasing apoptosis (4, 33, 34).…”

Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

“…Since then, the Ab hamster melanoma line has been maintained in vivo by consecutive subcutaneous transplantations of tumor material [ 73 , 74 , 75 ]. The hamster Ab melanoma cells were obtained for each experiment from solid tumors using a non-enzymatic method of cell isolation, as previously described [ 76 ]. The resection of the tumor was performed after 10–11 days of growth after the transplantation.…”