APOPTOSIS-LIKE, REVERSIBLE CHANGES IN PLASMA-MEMBRANE ASYMMETRY AND PERMEABILITY, AND TRANSIENT MODIFICATIONS IN MITOCHONDRIAL-MEMBRANE POTENTIAL INDUCED BY CURCUMIN IN RAT THYMOCYTES

Curcumin (diferuoylmethane) is a natural compound with anticarcinogeni c activities which is able to exert either proapoptotic or antiapoptot ic effects in different cell types, This paper focuses on the sequence and extent of primary events induced by curcumin, in comparison with those occurring during dexamethasone-induced apoptosis in rat thymocyt es, It also presents annexin VI-FITC as a new probe for studying membr ane asymmetry. Curcumin readily penetrates into the cytoplasm, and is able to accumulate in membranous structures such as plasma membrane, e ndoplasmic reticulum and nuclear envelope. Curcumin-treated cells exhi bit typical features of apoptotic cell death, including shrinkage, tra nsient phosphatidylserine exposure, increased membrane permeability an d decrease in mitochondrial membrane potential. However, nuclei morpho logy, DNA fragmentation, the extent and time-course of membrane change s are different from those observed during dexamethasone-induced apopt osis, suggesting that, despite many similarities, the mode of action a nd the events triggered by curcumin are different from those occurring during typical apoptosis, (C) 1998 Federation of European Biochemical Societies.