flavokawain-b and Mouth-Neoplasms

Kava is a beverage made from the ground roots of the plant Piper Methysticum. Active compounds of Kava have previously been demonstrated to exert an antiproliferative effect through cell cycle arrest and promotion of apoptosis. Our aim was to investigate the in vitro effects of the main constituents derived from Kava on oral squamous cell carcinoma (OSCC) activity. Gas chromatography mass spectrometry (GCMS) was used to characterise the main constituents of two Kava preparations. Cell proliferation was assessed in two human OSCC cell lines (H400 and BICR56) and in normal oral keratinocytes (OKF6) treated with the identified Kava constituents, namely Flavokawain A (FKA), Flavokawain B (FKB), yangonin, kavain and methysticin using an MTS in vitro assay. Cell migration at 16 h was assessed using a Transwell migration assay. Cell invasion was measured at 22 h using a Matrigel assay. Cell adhesion was assessed at 90 min with a Cytoselect Adhesion assay. The two Kava preparations contained substantially different concentrations of the main chemical constituents. Treatment of malignant and normal oral keratinocyte cell lines with three of the identified constituents, 10 μg/ml FKA, 2.5 μg/ml FKB and 10 μg/ml yangonin, showed a significant reduction in cell proliferation in both H400 and BICR56 cancer cell lines but not in normal OKF6 cells. Remarkably, the same Kava constituents induced a significant reduction of OSCC cell migration and invasion. We have demonstrated, for the first time, that Kava constituents, FKA, FKB and yangonin have potential anticancer effects on OSCC. This highlights an avenue for further research of Kava constituents in the development of future cancer therapies to prevent and treat OSCC.

Topics: Cell Line, Tumor; Cell Movement; Cell Proliferation; Chalcone; Flavonoids; Gas Chromatography-Mass Spectrometry; Humans; Kava; Keratinocytes; Mouth Neoplasms; Plant Extracts; Pyrans; Pyrones; Squamous Cell Carcinoma of Head and Neck

Chalcones have been described to represent cancer chemopreventive food components that are rich in fruits and vegetables. In this study, we examined the anti-oral cancer effect of flavokawain B (FKB), a naturally occurring chalcone isolated from Alpinia pricei (shell gingers), and revealed its molecular mechanism of action. Treatment of human oral carcinoma (HSC-3) cells with FKB (1.25-10 μg/mL; 4.4-35.2 μM) inhibited cell viability and caused G(2)/M arrest through reductions in cyclin A/B1, Cdc2, and Cdc25C levels. Moreover, FKB treatment resulted in the induction of apoptosis, which was associated with DNA fragmentation, mitochondria dysfunction, cytochrome c and AIF release, caspase-3 and caspase-9 activation, and Bcl-2/Bax dysregulation. Furthermore, increased Fas activity and procaspase-8, procaspase-4, and procaspase-12 cleavages were accompanied by death receptor and ER-stress, indicating the involvement of mitochondria, death-receptor, and ER-stress signaling pathways. FKB induces apoptosis through ROS generation as evidenced by the upregulation of oxidative-stress markers HO-1/Nrf2. This mechanism was further confirmed by the finding that the antioxidant N-acetylcysteine (NAC) significantly blocked ROS generation and consequently inhibited FKB-induced apoptosis. Moreover, FKB downregulated the phosphorylation of Akt and p38 MAPK, while their inhibitors LY294002 and SB203580, respectively, induced G(2)/M arrest and apoptosis. The profound reduction in cell number was observed in combination treatment with FKB and Akt/p38 MAPK inhibitors, indicating that the disruption of Akt and p38 MAPK cascades plays a functional role in FKB-induced G(2)/M arrest and apoptosis in HSC-3 cells.

Topics: Anticarcinogenic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Chalcones; Down-Regulation; Flavonoids; Humans; MAP Kinase Signaling System; Mouth Neoplasms; Reactive Oxygen Species

Novel effective drugs are still urgently needed in the prevention and treatment of oral adenoid cystic carcinoma (ACC). In this study, we have assessed the antitumor potential and molecular mechanisms of flavokawain B (FKB) as a kava chalcone on the ACC-2 cell line in vitro. The results demonstrated that FKB could significantly inhibit the cell proliferation of ACC-2 in a dose-dependent manner that was associated with induced apoptosis and cell cycle G2-M arrest, and the half maximal inhibitory concentration (IC50) of flavokawain-B treatment for 48 h was estimated to be 4.69 ± 0.43 µmol/L. Mechanistically, FKB could induce the release of cytochrome c from mitochondria into the cytosol, and activate the cleavage of caspase-3 and, eventually, the poly(ADP-ribose) polymerase (PARP), in a dose-dependent manner, leading to marked apoptotic effect of ACC-2 cells. The apoptotic action of FKB was associated with the increased expression of proapoptotic proteins: Bim, Bax, Bak and a decreased expression of antiapoptotic Bcl-2. Among them, Bim expression was significantly induced by FKB, and knockdown of Bim expression by short-hairpin RNAs attenuated the inhibitory effect induced by FKB on ACC-2 cells. These results suggest Bim may be one of the potential transcriptional targets, and suggests the potential usefulness of FKB for the prevention and treatment of ACC.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Carcinoma, Adenoid Cystic; Cell Line, Tumor; Cell Proliferation; Chalcone; Down-Regulation; Flavonoids; G2 Phase Cell Cycle Checkpoints; Humans; Inhibitory Concentration 50; M Phase Cell Cycle Checkpoints; Membrane Proteins; Mitochondria; Mouth Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Up-Regulation