The cholesterol-lowering medications, statins, inhibit cellular proliferation and induce apoptosis in an array of cancer cell lines, including melanoma. We investigated the apoptotic mechanism of lovastatin on human melanoma cell lines in vitro. The cytotoxicity of statins on multiple cell lines was examined by Cell Titer 96™ Aqueous One solution cell proliferation assay (MTS assay). Apoptosis was assayed by ethidium bromide and acridine orange morphologic assays, an Annexin V apoptosis detection kit and active caspase 3 assays. Farnesyl pyrophosphate and geranylgeranyl pyrophosphate add-back experiments were performed to better define the molecular mechanisms mediating lovastatin cytotoxicity. Lovastatin caused cytotoxicity in human and murine melanoma cells, but did not induce toxicity in an epidermoid carcinoma cell line A431. For human melanoma cells, lovastatin precipitated cell rounding, increased the percentage of apoptotic cells detected by ethidium bromide and acridine orange staining and by the Annexin V apoptosis detection kit, and resulted in a 50-fold increase in active caspase 3, corroborating that lovastatin induced apoptosis. Adding back geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, reversed the effects of lovastatin in A375 cells. Of the five statins tested, pravastatin was least effective in killing melanoma cells. Lovastatin induced caspase-dependent apoptosis in multiple melanoma cell lines via a geranylation-specific mechanism. This study supports a possible role of lovastatin as a therapeutic, adjuvant or chemopreventative agent for melanoma.
aDepartment of Dermatology, University of Colorado Health Science Center at Fitzsimons, Aurora, CO 80045, USA
bDepartment of Veterans Affairs Medical Center, Dermatology Section, Denver, CO 80220, USA
cDepartment of Preventive Medicine and Biometrics, University of Colorado Health Science Center, Denver, CO 80262, USA
Sponsorship: This work was supported in part by Dermatology Foundation career development award to Y.G.S. and by National Cancer Institute K-07 (CA92550-01A1) and an Atorvastatin Research Award from Pfizer Pharmaceuticals to R.D.
Correspondence and requests for reprints to Dr Yiqun G. Shellman, University of Colorado Health Science Center at Fitzsimons, Dermatology Department, Mail Stop ♯8127, PO Box 6511, Aurora, CO 80045, USA
Tel: (303) 724-4034; fax: (303) 724-4048;
Received 28 June 2004 Accepted (after revision) 26 November 2004