FLOW CYTOMETRIC EVALUATION OF SYNERGISTIC PRO‐APOPTOTIC EFFECTS OF STATINS AND CLOFIBRATES IN IM‐9 HUMAN LYMPHOBLASTS

SUMMARY 1 In the present study, we evaluated fibrate-mediated potentiation of statin-induced apoptosis in IM-9 human lymphoblasts. 2 The pro-apoptotic effects of statin and fibrate were measured by flow cytometry with biotin–annexin V, followed by addition of avidin–fluorescein isothiocyanate and propidium iodide. Apoptosis was confirmed using karyopyknotic staining, as well as detection of DNA fragmentation and caspase 3 activation. 3 Incubation of IM-9 cells with both 0.1 µmol/L cerivastatin and 200 µmol/L clofibrate had a synergistic effect compared with 0.1 µmol/L cerivastatin alone or 200 µmol/L clofibrate alone. The magnitude of apoptosis induced by various combinations of statins and clofibrate were as follows: cerivastatin (0.1 µmol/L) + clofibrate (200 µmol/L) > atorvastatin (0.1 µmol/L) + clofibrate (200 µmol/L) > pravastatin (100 µmol/L) + clofibrate (200 µmol/L). Other fibrates (bezafibrate and clinofibrate) did not show any synergistic effect. Furthermore, karyopyknotic staining, caspase 3 activation and DNA fragmentation demonstrated synergistic pro-apoptotic effects of statin and fibrate. 4 The results of the present study suggest that simultaneous treatment with statins and clofibrate could provide improved therapeutic efficacy in leukaemia patients.