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Analogs of farnesylcysteine induce apoptosis in HL-60 cells
D Pérez-Sala1, B A Gilbert, R R Rando
1Departamento de Estructura y Función de Proteínas, Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain. lperezsala@fresno.csic.es
Abstract:
S-Farnesyl-thioacetic acid (FTA), a competitive inhibitor of isoprenylated protein methyltransferase, potently suppressed the growth of HL-60 cells and induced apoptosis, as evidenced by the development of increased annexin-V binding, decreased binding of DNA dyes and internucleosomal DNA degradation. FTA did not impair the membrane association of ras proteins, conversely, it brought about a decrease in the proportion of ras present in the cytosolic fraction. Farnesylated molecules which are weak inhibitors of the methyltransferase also induced DNA laddering and reduced the proportion of cytosolic ras. These findings suggest that neither inhibition of isoprenylated protein methylation nor impairment of ras membrane association are essential for apoptosis induced by farnesylcysteine analogs.
Insights
S-Farnesyl-thioacetic acid (FTA) effectively inhibited cancer cell growth and induced apoptosis. However, this effect was independent of ras protein changes, suggesting alternative mechanisms for farnesylcysteine analog-induced cell death.
Area of Science:
- Biochemistry
- Cell Biology
- Cancer Research
Background:
- Isoprenylated protein methyltransferase is a target for cancer therapeutics.
- S-Farnesyl-thioacetic acid (FTA) is a known inhibitor of this enzyme.
- Ras proteins are key signaling molecules involved in cell growth and survival.
Purpose of the Study:
- To investigate the mechanism by which FTA suppresses cancer cell growth and induces apoptosis.
- To determine the role of ras protein prenylation and membrane association in FTA-induced apoptosis.
Main Methods:
- HL-60 cell line was treated with FTA.
- Apoptosis was assessed using annexin-V binding, DNA dye exclusion, and DNA laddering assays.
- Ras protein localization (cytosolic vs. membrane-associated) was analyzed via Western blotting.
Main Results:
- FTA potently suppressed HL-60 cell growth and induced apoptosis.
- FTA treatment did not affect the membrane association of ras proteins.
- FTA decreased the proportion of cytosolic ras, indicating a shift in its localization.
- Weak methyltransferase inhibitors also induced apoptosis and altered ras localization.
Conclusions:
- Inhibition of isoprenylated protein methylation is not essential for FTA-induced apoptosis.
- Impairment of ras membrane association is not required for apoptosis induced by farnesylcysteine analogs.
- The study suggests alternative pathways mediating the apoptotic effects of these compounds.