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Inhibition of growth factor signaling pathways by lovastatin
T S Vincent1, E Wülfert, E Merler
1Department of Microbiology and Immunology, Medical University of South Carolina, Charleston.
Abstract:
Human fibroblasts treated with the antihypercholesterolaemic drug, lovastatin, displayed a diminished signaling response to epidermal growth factor (EGF), insulin and insulin-like growth factor I (IGF-I). Supplementing the culture medium with mevalonic acid restored the signaling response. Not all growth factor signaling pathways were impaired, however, as platelet-derived growth factor (PDGF-BB) and basic fibroblast growth factor (bFGF) responses were refractory to lovastatin treatment. These results suggest the involvement of product(s) of mevalonate metabolism (e.g., prenylated proteins such as p21ras or G proteins) in the signal transduction of EGF, insulin and IGF-I. The inhibition of cell growth by lovastatin may be caused by the inability of the cell to enter the S phase of the cell cycle due to obstruction of the signaling of progression factors.
Insights
Lovastatin impairs cell signaling for epidermal growth factor (EGF), insulin, and insulin-like growth factor I (IGF-I) in human fibroblasts. Mevalonic acid supplementation restores these growth factor responses, suggesting a role for mevalonate metabolism products.
Area of Science:
- Cellular biology
- Biochemistry
- Pharmacology
Background:
- Lovastatin is an antihypercholesterolemic drug that inhibits HMG-CoA reductase.
- Cellular signaling pathways are crucial for cell growth and proliferation.
- Mevalonate is a key intermediate in the HMG-CoA reductase pathway.
Purpose of the Study:
- To investigate the effect of lovastatin on growth factor signaling in human fibroblasts.
- To determine if mevalonate supplementation can rescue impaired signaling.
- To identify specific growth factor pathways affected by lovastatin.
Main Methods:
- Human fibroblasts were treated with lovastatin.
- Cellular signaling responses to epidermal growth factor (EGF), insulin, insulin-like growth factor I (IGF-I), platelet-derived growth factor (PDGF-BB), and basic fibroblast growth factor (bFGF) were measured.
- Mevalonic acid was added to the culture medium to assess its restorative effects.
Main Results:
- Lovastatin treatment diminished signaling responses to EGF, insulin, and IGF-I.
- Responses to PDGF-BB and bFGF were not affected by lovastatin.
- Supplementation with mevalonic acid restored the signaling pathways impaired by lovastatin.
Conclusions:
- Products of mevalonate metabolism, potentially prenylated proteins like p21ras or G proteins, are involved in the signal transduction of EGF, insulin, and IGF-I.
- Lovastatin may inhibit cell growth by obstructing signaling pathways essential for cell cycle progression (S phase entry).