The Effect of Toremifene on Lipid Metabolism Compared with That of Tamoxifen in vitro

Background: Tamoxifen (TAM) and toremifene (TOR) prevent estrogen from stimulating breast cancer growth and also have agonistic effects in a number of physiological systems. TAM is known to increase intracellular triglyceride, but the action of TOR on lipid metabolism in vitro has not yet been determined. Aim: To compare the effect of TOR on lipid metabolism with that of TAM in vitro, using HepG2 cell lines. Methods: Intracellular concentrations of total cholesterol and triglyceride in HepG2 cells were measured by an enzymatic method after TAM or TOR treatment. Results: Intracellular concentrations of total cholesterol were decreased by both TAM and TOR, but not significantly different from the control level. TOR produced no changes in the intracellular concentrations of triglyceride, whereas TAM increased the intracellular concentrations of triglyceride at concentrations ranging from 10 –7 to 10 –5 mol/l of TAM (p < 0.05). Moreover, significant differences were noted between the two treated groups at concentrations ranging from 10 –9 to 10 –5 mol/l (p < 0.05). Conclusion: TOR treatment did not increase intracellular concentrations of triglyceride, although TAM treatment did so.