Interleukin-2 enhances the growth of human melanoma cells derived form primary but not from metastatic tumours.

Previously, we demonstrated that in vitro treatment of B16F10 murine melanoma cells with interleukin-2 (IL-2) enhances proliferation and metastasis. To further investigate the role played by IL-2 in human melanomas, we studied the expression of IL-2/IL-2 receptor and the effect of IL-2 on the proliferation of melanoma cell lines derived from primary (A375 and RMS cell lines) and metastatic (Hs294T cell line) tumours. We found a constitutive expression of cytoplasmic IL-2 and alpha, beta and gamma-subunits of the IL-2R on the surface of the three melanoma cell lines. The presence of IL-2 in the culture increased the proliferation rate in A375 and RMS cell lines, but no effect was observed in Hs294T metastatic cells. Biologically active IL-2 could be found in the supernatant of the three melanoma cell lines, particularly in A375 and RMS cells, in which an inhibition of the proliferation rate was observed when IL-2 was blocked. Moreover, the combination of anti-IL-2R beta and anti-IL-2R gamma blocking antibodies induced a significant down-regulation of cell proliferation in the three melanoma cell lines, and the combination of anti-IL-2R alpha, anti-IL-2R beta and anti-IL-2R gamma blocking antibodies inhibited IL-2-mediated growth stimulation in A375 and Hs294T cell lines. In RMS cells, a more significant effect was observed when only IL-2R gamma was blocked. Finally, exogenous IL-2 modulated the IL-2 endogenously produced by melanoma cells. These data show that IL-2 may modulate the growth of melanoma cells through autocrine or/and paracrine mechanisms.

Effect induced by interleukin-1 on the behaviour of B16F10 melanoma cells.

We have previously demonstrated that in vitro treatment with interleukins (IL-2 and IL-6) enhances metastasis in B16 murine melanoma. IL-1 has been reported to be involved in the metastatic activity of human melanoma; so in the present study we have investigated if IL-1 could also modulate the behaviour of this experimental tumor. Data showed that low doses of IL-1 induced cell proliferation and several modifications in the expression of MHC antigens, fibronectin and laminin, however these changes did not lead to a higher metastatic efficiency. In addition it was shown that B16F10 cells express IL-1 mRNA. It can be concluded that IL-1 may be involved in the biology of B16F10 cells although its role in metastasis needs further investigation.

Cyclosporin A upmodulates the alpha-subunit of the interleukin-2 receptor and the metastatic ability of murine B16F10 melanoma cells.

In the present study, the effect of in vitro cyclosporin A (CsA) treatment on IL-2R expression and the metastatic behavior of B16F10 melanoma cells has been reported. CsA treatment was found to increase the percentage of B16F10 cells expressing the alpha-subunit of IL-2R on the cell surface and also at the mRNA level. Moreover, CsA treated B16F10 cells also express the beta-subunit of IL-2. In vivo experiments showed that CsA increases the affinity of B16F10 metastazing cells for the liver and decreases that for the lung. CsA modulated the expression of MHC class I and class II antigens, but no significant differences in the resistance of CsA-treated B16F10 cells to NK lysis were observed. Finally, proliferation of B16F10 cells in the presence of several doses of CsA did not vary and CsA increased the amount of IL-1beta mRNA expression. These results suggest that CsA, through the modulation of cytokines and MHC antigen expression on B16F10 cells, could have an effect upon the metastatic progression of the B16F10 melanoma.