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Recombinant immune interferon down-regulates Ha-ras-1 proto-oncogene products in a human melanoma cell line
P Giacomini1, R Gambari, R Barbieri
1Immunology Laboratory, Regina Elena Institute, Rome, Italy.
Abstract:
The antiproliferative and antineoplastic effects of the interferons may result, at least in part, from changes in the expression and quantity of specific oncogene products. To explore this hypothesis we have determined the effect of interferons, including recombinant leukocyte (IFN-alpha), fibroblast (IFN-beta) and immune (IFN-gamma), on expression of the Ha-ras proto-oncogene in the human melanoma cell line Colo 38. While concentrations of up to 1000 U/ml of either IFN-alpha or IFN-beta did not affect the total amounts of Ha-ras products, IFN-gamma at concentrations ranging from 20 to 200 U/ml caused a dose- and time-dependent (48-96 hr) reduction (approximately 40%) in the accumulation of Ha-ras-1 mRNA and in the synthesis of the specific protein products. Downregulation of this proto-oncogene occurs prior to the antiproliferative effects of IFN-gamma and parallels similar IFN-gamma mediated changes in the expression of certain melanoma associated antigens. The present findings indicate that this experimental model may prove valuable in determining whether a direct relationship exists between the antiproliferative activity of specific interferons and the downregulation of oncogene expression.
Insights
Interferon-gamma (IFN-gamma) reduces Ha-ras oncogene expression in melanoma cells, potentially explaining its antiproliferative effects. This finding suggests a link between oncogene downregulation and interferon therapy efficacy.
Area of Science:
- Oncology
- Molecular Biology
- Immunology
Background:
- Interferons (IFNs) exhibit antiproliferative and antineoplastic properties.
- These effects may stem from altered expression of specific oncogene products.
- The Ha-ras proto-oncogene is implicated in various cancers, including melanoma.
Purpose of the Study:
- To investigate the impact of different interferons (IFN-alpha, IFN-beta, IFN-gamma) on Ha-ras proto-oncogene expression.
- To determine if IFN-gamma downregulates Ha-ras expression in human melanoma cells (Colo 38).
- To explore the relationship between oncogene downregulation and the antiproliferative activity of interferons.
Main Methods:
- Treatment of human melanoma cell line Colo 38 with recombinant leukocyte IFN-alpha, fibroblast IFN-beta, and immune IFN-gamma.
- Quantification of Ha-ras-1 mRNA levels and synthesis of specific protein products.
- Dose- and time-course analysis of interferon effects.
Main Results:
- IFN-alpha and IFN-beta (up to 1000 U/ml) did not alter Ha-ras product levels.
- IFN-gamma (20-200 U/ml) caused a dose- and time-dependent reduction (approx. 40%) in Ha-ras-1 mRNA and protein.
- This downregulation preceded the antiproliferative effects of IFN-gamma and correlated with changes in melanoma-associated antigens.
Conclusions:
- IFN-gamma effectively downregulates Ha-ras proto-oncogene expression in human melanoma cells.
- This downregulation occurs before observable antiproliferative effects, suggesting a mechanistic link.
- The findings support the use of this melanoma model to study the relationship between interferon-induced oncogene downregulation and therapeutic efficacy.