A survey of cytokine production by cultured human melanoma cells and characterization of melanoma-derived interleukin-1
Abstract
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.
Subject Area
Immunology|Cellular biology
Recommended Citation
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.
https://repository.upenn.edu/dissertations/AAI9308533