Flavones inhibit the proliferation of human tumor cancer cell lines by inducing apoptosis.

Dietary flavonoids have been shown to exert specific cytotoxicity toward some cancer cells, but the precise molecular mechanisms are still not completely understood. In this study, cytotoxic effects of flavones (apigenin and luteolin) on two different cancer cell lines, including human chronic myelogenous erythroleukaemia (K562) and bladder carcinoma (RT112), were determined, and the molecular mechanisms responsible for their cytotoxic effects were studied. The results of an MTT assay showed that luteolin and apigenin were able to induce cytotoxicity in K562 and RT112 cells in a dose- and time-dependent manner. The cytotoxic potency of luteolin was higher than that of apigenin. Flow-cytometry and DNA-fragmentation analysis indicated that the cytotoxicity induced by luteolin and apigenin was mainly due to apoptosis, with minor cell-cycle perturbations. This apoptotic response was characterized by an increase of the sub-G1 fraction of treated cells, poly(ADP-ribose) polymerase proteolysis, typical ladder of DNA fragmentation, and Annexin V-positive cells. In conclusion, luteolin and apigenin exert cytotoxic effects in different cancer cell lines in which apoptosis plays an important role. Thus, flavones could be considered as potential chemotherapeutic agents.