Abstract
: Evidence has accumulated that dietary polyphenols, in particular, flavonoids, have protective effects against oral cancer. In this study, we have examined the effects of quercetin, a major dietary flavonoid, on cell growth and necrosis/apoptosis and cell cycle regulation in human oral squamous carcinoma SCC-9 cells. Quercetin induced dose- and time-dependent, irreversible inhibition of cell growth and cellular DNA synthesis. Light microscopy and lactate dehydrogenase measurements showed modifications in the morphology and membrane integrity of these cells after quercetin treatment. Propidium iodide/annexin V staining showed that quercetin induced necrosis at 24 h and 48 h, whereas at 72 h cells underwent apoptosis, correlating with caspase-3 activation. Flow cytometry studies of the cell cycle distribution showed that quercetin induced mainly S-phase arrest. Thymidylate synthase (TS), a key S-phase enzyme, was inhibited in a time- and dose-dependent fashion by quercetin at the protein level. A lack of effect on TS mRNA suggested that TS down-regulation occurred at the translational level. In conclusion, our data support a view that quercetin initially induces a stress response, resulting in necrosis of these oral epithelial cells. Prolonged exposure of the surviving cells to quercetin causes apoptosis, presumably mediated by inhibition of TS protein.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.