Sodium Phenylbutyrate Inhibits Tumor Growth and the Epithelial-Mesenchymal Transition of Oral Squamous Cell Carcinoma In Vitro and In Vivo.

Sodium phenylbutyrate (SPB) as a salt of 4-phenylbutyric acid (4-PBA) has been reported to be an ammonia scavenger, histone deacetylase inhibitor, and an endoplasmic reticulum stress inhibitor in various diseases, including neurological diseases, inflammatory disorders, and carcinogenesis. Although phenylbutyrate showed effective antitumor properties in many cancers, its role in oral squamous cell carcinoma (OSCC) remains further characterized. Thus, the OSCC cell lines CAL27, HSC3, and SCC4 were treated with a series of doses of SPB for different times. The IC of three cell lines for SPB was determined to be 4.0, 3.7, and 3.0 mM. The CCK-8 assay indicated that the treatment of SPB induced continuous inhibition of cell vitality of three cell lines. Apoptosis was assessed by Hoechst assay that showed that SPB could significantly promote cell apoptosis. Moreover, the apoptosis-related pathway was analyzed, and the results showed that the expression of antiapoptosis factor BCL-2 was downregulated by SPB but the cleavage of caspase-3 was increased. Meanwhile, it was found that SPB also impaired the migration and invasion of OSCC cells in vitro. Mechanistically, the transforming growth factor-β (TGFB) related epithelial-mesenchymal transition (EMT) was inhibited by SPB with decreased mesenchymal marker N-cadherin and increased epithelial marker E-cadherin. Furthermore, the antitumor effect of SPB in vivo was also demonstrated. The administration of SPB induced remarkably tumor regression with decreased tumor volume, and the TGFB level and EMT phenotype in vivo were also inhibited. These data demonstrated that the treatment of SPB could function as antitumor therapeutics for OSCC.