Luteolin induces apoptosis by activating Fas signaling pathway at the receptor level in laryngeal squamous cell line Hep-2 cells

Luteolin, a naturally occurring flavonoid, possesses anti-cancer activities against several human cancers, but the exact molecular and biochemical mechanisms of above findings are not very clear, and its activity against head and neck squamous cell carcinoma (HNSCC) is seldom mentioned. In this study, we investigated luteolin against human laryngeal squamous cell line Hep-2 cells, using MTT assay, flow cytometry, Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Luteolin inhibited Hep-2 cells proliferation at the inhibitive concentrations of 50 % (IC50) near to 50 mu M and induced the apoptosis in Hep-2 cells through caspase-3 and caspase-8 activation. Up-regulation of Fas and down-regulation of long form cellular FLICE-like inhibitory protein (c-FLIPL) protein were also involved after luteolin treatment at both protein and mRNA levels. Luteolin could not only inhibit cell proliferation but also induce apoptosis by activating the Fas signaling pathway at the receptor level in laryngeal squamous cell line Hep-2 cells.