Effects and Mechanisms of Fucoxanthin from Hizikia fusiforme on Inhibiting Tongue Squamous Cell Carcinoma Proliferation via AKT/mTOR-Mediated Glycolysis

Fucoxanthin, a natural carotenoid, contains special ene bonds and 5, 6-mono-epoxide compounds in its molecule, which has physiological activities such as anticancer, antioxidant, anti-inflammatory, antiobesity, and antidiabetic. However, the anticancer actions and underlying mechanisms of fucoxanthin on oral cancer remain to be assessed. In this study, we used tongue carcinoma (CAL-27) cells to examine the effects and underlying mechanisms of fucoxanthin derived from Hizikia fusiforme on CAL-27 proliferation. MTT assays were used to estimate fucoxanthin’s effect on the proliferative capacity of CAL-27 cells. Flow cytometry was used to examine how fucoxanthin affects apoptosis initiation and alters cell cycle progression in CAL-27 cells. Spectrophotometry was used to assess the impact of fucoxanthin on adenosine triphosphate (ATP) generation, glucose uptake, lactate production, and the enzymatic activities of pyruvate kinase and hexokinase in CAL-27 cells. Western blotting was used to investigate fucoxanthin’s impact on the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway and glycolysis-related protein expression levels in CAL-27 cells. Fucoxanthin significantly inhibited CAL-27 cell viability time- and dose-dependently $\left(p<0.01\right)$ . Administration of fucoxanthin induced CAL-27 cell apoptosis and cell cycle arrest at the G1 phase $\left(p<0.05\right)$ . Furthermore, fucoxanthin significantly decreased glucose uptake, lactate production, and ATP production in CAL-27 cells $\left(p<0.01\right)$ and significantly inhibited glycolysis-related enzyme activities and protein expression levels $\left(p<0.05\right)$ . Fucoxanthin also substantially decreased the expression levels of phosphorylated ribosomal protein S6, phosphorylated AKT, and phosphorylated mTOR $\left(p<0.05\right)$ . In conclusion, fucoxanthin inhibited CAL-27 cell proliferation, and this mechanism may be associated with the AKT/mTOR-mediated glycolysis pathway.