Liquiritigenin Induces Cell Cycle Arrest and Apoptosis in Lung Squamous Cell Carcinoma

Liquiritigenin (LQ), as a dihydroflavone monomer compound extracted from Glycyrrhiza uralensis Fisch, has been demonstrated to show anti-tumor effects in multiple human cancers, including lung adenocarcinoma. Our study aimed to explore its role in lung squamous cell carcinoma (LSCC) development and the related mechanism. The effects of LQ on SK-MES-1 and NCI-H520 cell proliferation, cell cycle, and apoptosis were investigated. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays revealed that LQ inhibited LSCC cell viability and proliferation in a dose- and time-dependent manner. Flow cytometry analysis demonstrated that LQ promoted G2/M cell cycle arrest, cell apoptosis, and loss of mitochondrial membrane potential. In vivo assays showed that LQ administration suppressed tumor growth in nude mice. Additionally, LQ treatment reduced the levels of phosphorylated PI3K, AKT, and mTOR levels in LSCC cells. Pretreatment with the PI3K inhibitor LY294002 antagonized the LQ-mediated effects on cell proliferation, cell cycle arrest, and apoptosis in LSCC cells. Collectively, LQ induces cell cycle arrest and apoptosis in LSCC by inactivating the PI3K/AKT/mTOR pathway.