Action of resveratrol alone or in combination with roscovitine, a CDK inhibitor, on cell cycle progression in human HL-60 leukemia cells

Results of a number of epidemiological and experimental studies indicate that polyphenols (e.g. resveratrol (RES), epicatechins etc.), antioxidant agents and abundant micronutrients in our food could have strong anti-mitotic as well as pro-apoptotic effects. In this study we raised the question whether roscovitine (ROSC), an inhibitor of cyclin-dependent kinases (CDKs) with increased selectivity towards CDK2, could be able to affect human leukemia HL-60 cells in which the p53 gene is inactivated and whether ROSC-induced effects could be additionally modulated by compounds of natural origin, especially by polyphenols e.g. RES. Exposure of HL-60 cells to ROSC for 24 h inhibited their proliferation. Flow cytometric analyses revealed that unlike MCF-7 cells, HL-60 cells were arrested in G1 upon ROSC treatment. Furthermore, ROSC also induced apoptosis in HL-60 cells. After treatment with 40 μM ROSC for 24 h the frequency of hypoploid cells representing cells undergoing apoptosis reached approximately 50%. In the next step the action of RES alone or in combination with ROSC was examined. Interestingly, synergistic effects were observed after combined treatment for 24 h and sequential post-incubation for 48 h in the presence of RES. Such combined treatment resulted in a marked reduction of the frequency of the S- and G2/M-phase cells and simultaneously increased the G1 cell population up to 80% at a fourfold lower ROSC dose. Further analyses revealed that the combined treatment strongly activated caspase-3. These results clearly evidence that RES strongly potentiates ROSC-induced apoptosis.