Sulforaphane induces growth arrest and apoptosis in human ovarian cancer cells

Abstract

Isothiocyanates (ITC) from broccoli and other cruciferous vegetables have long been shown to have chemopreventive properties, as demonstrated in cancer models in rodents. Sulforaphane (SFN) is a major ITC present in broccoli. We examined the effects of SFN on the growth of the OVCAR-3 and SKOV-3 ovarian carcinoma cell lines. Cell cycle phase determination was performed using a Coulter flow cytometer. DNA strand breaks in apoptotic cells were measured by terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end-labelling (TUNEL). There was a concentration dependent decrease in cell density. Approximately 50% decrease was observed after 48 h of incubation with SFN (2 μM). Analysis of cell cycle phase progression revealed a decrease in the cell populations in S and G2M phases, with an increase of G1 cell population, indicating a G1 cell cycle arrest. The degree of decrease in the replicating population was concentration and time dependent. Incubation of OVCAR-3 cells in cultures with concentrations of 2, 10 and 50 μM of SFN showed 6, 8 and 17% apoptosis, respectively. In addition, when OVCAR-3 cells were exposed to SFN for various time periods (1, 2 or 3 days), the percentage of cells undergoing apoptosis was directly proportional to the incubation period. In this regard, while 18% of the cells underwent apoptosis after 2 days, 42% of the cells showed apoptosis after 3 days of incubation. These results clearly demonstrated an effect of SFN in inducing growth arrest and apoptosis in ovarian carcinoma cell lines.