The Chalcone Flavokawain B Induces G₂/M Cell-Cycle Arrest and Apoptosis in Human Oral Carcinoma HSC-3 Cells through the Intracellular ROS Generation and Downregulation of the Akt/p38 MAPK Signaling Pathway

Abstract

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.

Flavokawains A and B from kava (Piper methysticum) activate heat shock and antioxidant responses and protect against hydrogen peroxide-induced cell death in HepG2 hepatocytes

“…The flavokawains, FKA and FKB have demonstrated efficacy in both cell culture and animal models for the treatment of various cancers (Abu et al, 2014, 2015; An et al, 2012; Hseu et al, 2012; Liu et al, 2013; Tang et al, 2010). Although FKA kills cancer cells and limits tumor growth, it has no apparent toxicity to HepG2 hepatocytes in our experiments.…”

Nifurtimox reduces N-Myc expression and aerobic glycolysis in neuroblastoma

“…39 However, further investigations have to be done to explain the detailed mechanisms that lead to the interrupted cell cycle progression after nifurtimox treatment. The presented data shows that oxidative stress is actually induced by nifurtimox but rather in high nifurtimox doses and not to the extent as expected.…”

Anti-tumor effect of α-pinene on human hepatoma cell lines through inducing G2/M cell cycle arrest

“…For example, dual specificity phosphatase CDC25C activates CDC2 via upholding phosphorylation on the Thr14 and Tyr15 of CDC2 (15). p53 also plays a role on the guardian of G2/M check point; p53 activates the transcription of p21 and 14-3-3s (16,17). While p21 directly suppresses activities of CDC2 (18), and interferes with PCNA and CDC25 (19), 14-3-3s binds to CyclinB1 and excludes it from the nucleus (20).…”