Carcinogenesis
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The effects of lovastatin, a potent inhibitor of hydroxymethylglutaryl-coenzyme A reductase, were studied in a mouse model of metastatic mammary cancer carrying a p53 mutation. Mice bearing mammary tumors, induced by inoculation of syngeneic BALB/c mice with BJMC3879 cells, were treated with lovastatin at 0, 25 and 50 mg/kg three times a week. Tumor volumes were significantly reduced in a dose-dependent manner throughout the 6 week study and were associated with both a decrease in DNA synthesis and an increase in apoptosis. ⋯ However, lovastatin-induced cell death was significantly reduced by the broad spectrum caspase inhibitor z-VAD-fmk, as well as the caspase-9 inhibitor z-LEHD-fmk and the caspase-3 inhibitor z-DEVD-fmk, but not by the specific caspase-8 inhibitor z-IETD-fmk. Since immunoelectron microscopy showed translocation of Bax to the mitochondria in lovastatin-treated cells, lovastatin-induced apoptosis may, therefore, be ultimately dependent on Bax induction of cytochrome c release. These results suggest that lovastatin may be useful as an adjuvant therapy in breast cancers containing p53 mutations due to its ability to both suppress DNA synthesis and induce p53-independent mitochondria-mediated apoptosis.