Cell cycle regulation and induction of apoptosis by β-carotene in u937 and HL-60 leukemia cells

In this communication, we report the efficacy of P-carotene towards differentiation and apoptosis of leukemia cells. Dose (20 mu M) and time dependence (12 h) tests of P-carotene showed a higher magnitude of decrease (significance p < 0.05) in cell numbers and cell viability in HL-60 cells than U937 cells but not normal cell like Peripheral blood mononuclear cell (PBMC). Microscopical observation of P-carotene treated cells showed a distinct pattern of morphological abnormalities with inclusion of apoptotic bodies in both leukemia cell lines. When cells were treated with 20 mu M of beta-carotene, total genomic DNA showed a fragmentation pattern and this pattern was clear in HL-60 than U937 cells. Both the cell lines, on treatment with beta-carotene, showed a clear shift in G, phase of the cell cycle. In addition the study also revealed anti-oxidant properties of P-carotene since there was reduction in relative fluorescent when treated than the control at lower concentration. Collectively this study shows the dual phenomenon of apoptosis and differentiation of leukemia cells on treatment with beta-carotene.