The present study investigated the cytotoxic effects of
statins (
atorvastatin (ATR) and
simvastatin (SIM), resp.) and
methyl-beta-cyclodextrin (MβCD), at their respective IC50 concentrations, on muscle regeneration in the in vitro model of murine C2C12 myoblasts. Cotreatment with
mevalonate (MEV),
farnesol (FOH),
geranylgeraniol (GGOH), or water-soluble
cholesterol (Chol-PEG) was employed to determine whether the
statin-dependent
myotoxicity resulted from the lower
cholesterol levels or the attenuated synthesis of intermediates of
mevalonate pathway. Our findings demonstrated that while GGOH fully reverted the
statin-mediated cell viability in proliferating myoblasts, Chol-PEG exclusively rescued MβCD-induced toxicity in myocytes.
Statins caused loss of prenylated RAP1, whereas the GGOH-dependent positive effect was accompanied by loss of nonprenylated RAP1. Geranylgeranyltransferases are essential for muscle cell survival as inhibition with
GGTI-286 could not be reversed by GGOH cotreatment. The increase in cell viability correlated with elevated AKT 1(S463) and GSK-3β(S9) phosphorylations. Slight increase in the levels of autophagy markers (
Beclin 1, MAP LC-3IIb) was found in response to GGOH cotreatment. Autophagy rose time-dependently during myogenesis and was inhibited by
statins and MβCD.
Statins and MβCD also suppressed myogenesis and neither nonsterol
isoprenoids nor Chol-PEG could reverse this effect. These results point to GGOH as the principal target of
statin-dependent
myotoxicity, whereas plasma membrane
cholesterol deposit is ultimately essential to restore viability of MβCD-treated myocytes. Overall, this study unveils for the first time a link found between the GGOH- and Chol-PEG-dependent reversal of
statin- or MβCD-mediated
myotoxicity and cytoprotective autophagy, respectively.