Apoptosis Induction by Curcumin in Human Myelogenous Leukemia Cell Lines

ABSTRACT

BACKGROUND: Curcumin, a naturally occurring biologically active compound extracted from rhizomes of Curcuma species, has been shown to possess potent anti-inflammatory, anti-tumor and anti-oxidative properties. The effects and possible mechanism of this agent were investigated on 2 human myelogenous leukemic cell lines. METHODS: K562 and KG-1 cells were the two cell lines selected. The MTT assay and flow cytometry were used to assess the cytotoxicity and for cell cycle analysis, respectively. The protein expressions were analyzed by Western blotting; the caspase activity was also checked. RESULTS: Both cell lines showed dose-dependent susceptibility to curcumin, and the cell cycle analysis showed an increased sub-G1 phase in the KG-1 cells. In the K562 cell, curcumin down regulated the expressions of PCNA (proliferating cell nuclear antigen) and cyclins D1 and B1. The expression of Akt was also down-regulated, but caspase-3 was activated to induce cleaved PARP (polyadenosine ribose polymerase) and apoptosis. However, the expression of phospho-Erk was unaffected. Co-treatment of cyclosporin A (CsA) with curcumin resulted in an attenuation of apoptosis in the K562 cells, implying curcumin-induced apoptosis is dependent on the release of cytochrome c from the mitochondria. CONCLUSION: Curcumin induced cell cycle arrest and apoptosis in both human myelogenous leukemic cell lines, with the apoptosis appearing to be dependent on the release of cytochrome c from the mitochondria.