Effect of mast cell products and histamine on the proliferative behaviour of human melanoma and carcinoma cells in vitro

The functional importance of mast cells in modifying tumour cell behaviour has long been recognised and recent evidence suggests that mast cell: tumour interactions contribute to the growth and development of specific cancers. We have used in vitro studies to examine such interactions in relation to tumour cell proliferation. Soluble mast cell products (MCP) were prepared from Furth mastocytoma cells at 106 cells/ml. The addition of MCP (10% v/v) to cultures of human melanoma cells (SK 23 and DX3.LT5.1), breast carcinoma cells (8701-BC) and normal skin fibroblasts resulted in increased rates of cell proliferation. Although histamine H2 receptors are expressed by the melanoma cells, the addition of exogenous histamine (5 and 25 μM) had no effect on the proliferative rate of the human melanoma cell lines, or on carcinoma cells derived from breast and prostate. The data indicate that exogenous histamine was not mitogenic for three tumour cell cultures and that other factors derived from mast cells appear to be essential for the increased proliferative response.