Caffeic Acid Phenethyl Ester and Caffeamide Derivatives Suppress Oral Squamous Cell Carcinoma Cells

Abstract

Caffeic acid phenethyl ester (CAPE) contains antibiotic and anticancer activities. Therefore, we aimed to investigate the anticancer properties and mechanisms of CAPE and caffeamide derivatives in the oral squamous cell carcinoma cell (OSCC) lines SAS and OECM-1. The anti-OSCC effects of CAPE and the caffeamide derivatives (<b>26G</b>, <b>36C</b>, <b>36H</b>, <b>36K</b>, and <b>36M</b>) were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Cell cycle and total reactive oxygen species (ROS) production were analyzed using flow cytometry. The relative protein expression of malignant phenotypes was determined via Western blot analysis. The results showed that <b>26G</b> and <b>36M</b> were more cytotoxic than the other compounds in SAS cells. After <b>26G</b> or <b>36M</b> treatment for 48 h, cell cycle S phase or G2/M phase arrest was induced, and cellular ROS increased at 24 h, and then decreased at 48 h in both cell lines. The expression levels of cell cycle regulatory and anti-ROS proteins were downregulated. In addition, <b>26G</b> or <b>36M</b> treatment inhibited malignant phenotypes through mTOR-ULK1-P62-LC3 autophagic signaling activated by ROS generation. These results showed that <b>26G</b> and <b>36M</b> induce cancer cell death by activating autophagy signaling, which is correlated with altered cellular oxidative stress.