A survey of cytokine production by cultured human melanoma cells and characterization of melanoma-derived interleukin-1
This thesis examines the hypothesis that melanoma cells produce immunomodulatory and growth regulatory cytokines which influence tumor growth and progression. Screening assays of melanoma conditioned media demonstrated bioactivity for IL-1, TGF-$\beta$, and IFN, but not IL-2. Immunoassays detected IL-1$\alpha$, IL-1$\beta$, IL-6, IL-8, and GM-CSF, but not IL-3, IL-4, TNF-$\alpha$, or IFN-$\gamma$. Melanoma-derived IL-1 was characterized: Constitutive secretion and/or cell surface expression occurred in more than 50% of cultures, with poly(I):poly(C) causing upregulation and r-IL-1$\alpha$ causing down-regulation. Melanomas secreting IL-1 expressed 2.2 and 1.6 kb transcripts hybridizing IL-1$\alpha$ and IL-1$\beta$ probes, respectively. When cloned and sequenced from cell line WM1158, the melanoma IL-1$\beta$ gene was identical to the monocyte gene; but several clones of the IL-1$\alpha$ gene contained two variations of unknown significance. Although melanoma and monocyte IL-1 are products of the same genes, differences were found in their expression. LPS-treated monocytes secreted at least 10-fold more IL-1 than cultured melanomas, in a ratio of 1 (IL-1$\alpha$) to 10 (IL-1$\beta$); while IL-1$\alpha$ predominated in melanomas. While cell-associated IL-1 precursors were identical in size, secreted melanoma IL-1 was larger than monocyte IL-1. In addition, LPS, silica, and zymosan failed to induce IL-1 secretion in a panel of melanoma cell lines, suggesting that in contrast to monocytes, melanoma IL-1 expression is not a generally inducible phenomenon. Finally, evidence is presented for an IL-1 autocrine growth-regulatory loop in some melanomas. Cultured melanomas expressed mRNA for IL-1 type I and II receptors, and exogenous IL-1$\alpha$ altered proliferation in 3/4 lines which expressed receptor message. The effects of exogenous IL-1 were influenced by culture conditions. Under suboptimal conditions, IL-1 caused either an acceleration (1/4 lines) or delay (1/4 lines) in the onset of quiescence, and culture with MAb to r-IL-1$\alpha$ resulted in the opposite effects. In W489PF medium, cultures underwent sustained proliferation, and IL-1$\alpha$ either decreased (2/6 lines) or had no effect (4/6 lines) on ($\sp3$H) -thymidine incorporation. In conclusion, these data demonstrate that melanoma cells produce immunomodulatory and growth regulatory cytokines and suggest that both exogenous and endogenous IL-1$\alpha$ regulate the proliferation of some melanomas.
Bennicelli, Jeannette L, "A survey of cytokine production by cultured human melanoma cells and characterization of melanoma-derived interleukin-1" (1992). Dissertations available from ProQuest. AAI9308533.