Curcumin induces cell cycle arrest and apoptosis in human osteosarcoma (HOS) cells

Curcumin is a major component of Curcuma longa rhizome and has been used as a traditional medicine for centuries. In this study, we showed that curcumin induced cell cycle arrest followed by antiproliferation and apoptosis in human osteosarcoma (HOS) cells.

Antiproliferative activity was measured with the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Nuclear fragmentation was observed with a fluorescence microscope. Flow cytometry was performed to observe cell cycle distribution and apoptotic body appearance. Changes in cell cycle regulatory and apoptosis-related proteins were investigated by Western blot analysis.

The IC(50) value of curcumin was approximately 4.0 microg/ml. Induction of apoptosis was evidenced by apoptotic body appearance and chromosomal DNA degradation. Flow-cytometric analysis indicated that curcumin induced successive G(1)/S and G(2)/M phase arrest followed by apoptosis in HOS cells. The G(1)/S and G(2)/S phase arrest was accompanied by down-regulation of cyclin D1, cdc2 and cyclin B1, respectively. Apoptosis was induced by capspase-3 activation and poly(ADP-ribosyl)polymerase (PARP) cleavage.

Our results demonstrated that curcumin caused death of HOS cells by blocking cells successively in G(1)/S and G(2)/M phases and activating the caspase-3 pathway.