A Combination Therapy of Cisplatin and Lovastatin Reduces Ras Activation in an A375 Melanoma Cell Line

Abstract

In many cancers mutations in the Ras protein lead to cancer growth and metastasis. In a mutated form, Ras allows cells to avoid a normally programed death called apoptosis. Ras is a GTP‐binding protein and attaches to the cell membrane through a prenylated tail. When attached, it will activate and signal for the promotion of cell survival. The prenylated tail and membrane insertion will keep Ras in its activated state. Typical antineoplastic agents are highly toxic therapies, but by using them in combination with alternative therapies such as lovastatin, proliferating cells may be held in check with reduced side effects. The purpose of these experiments was to examine Ras prenylation and activation in a melanoma cell line, following treatment with a combination of lovastatin and cisplatin. Flow cytometry using annexin‐V apoptosis assay was performed to determine drug toxicities for each drug and in combination. Melanoma cells were treated for 48 with 10 uM lovastatin, then 1.5 ug/ml cisplatin was added for an additional 24 hr. Membrane localization of Ras was determined using immunohistochemistry followed by analysis with ImageJ software. The results show that Ras localization to the membrane in cells undergoing the combined treatment was reduced 4‐fold relative to cisplatin alone (p<0.05). These results indicate that statin therapy combined with traditional cancer drugs such as cisplatin may be more effective at slowing cancer growth with lower toxicities, than with cisplatin alone.Support or Funding InformationSupported by the NIH Common Fund, through the Office of Strategic Coordination, Office of the NIH Director with the linked awards: TL4GM118992, RL5GM118990, & UL1GM118991 and a Fort Lewis College Undergraduate Research Grant.