The cinnamaldehyde-thiosemicarbazone-zinc (II) complex induces apoptosis in CAL-27 cells

Oral squamous cell carcinoma (OSCC) is a major malignancy affecting the oral, jaw, and facial regions. In this study, we synthesized a cinnamaldehyde-thiosemicarbazone-zinc (II) complex (CTZn) to inhibit OSCC cell proliferation.

We investigated the inhibitory effects of CTZn on OSCC using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell colony formation assays, wound-healing/scratch assays and transwell invasion assays. Flow cytometry (FCM) was performed to explore the CTZn's impact on apoptosis and cell-cycle progression. Through in vivo experiments, its antitumor activity activity was evaluated in OSCC xenograft mouse models and orthotopic tumor model mice. The mechanisms of CTZn were explored by detecting targeted metabolites, and performing drug affinity responsive target stability (DARTS) experiments, molecular docking analyses and Western blot assays. Levels of reactive oxygen species (ROS), oxidized and reduced nicotinamide adenine dinucleotide phosphate (NADP⁺/NADPH), glutathione (GSH), and 6-phosphogluconate dehydrogenase (PGD) protein in CAL-27 cells were also determined.

These findings demonstrated that CTZn inhibited CAL-27 cell growth in vitro in a time- and concentration-dependent manner, with an IC₅₀ value of 1.642-2.223μmol/L, and CTZn also exerted anti-tumor activity in vivo. CTZn also inhibited PGD messenger RNA (mRNA), and protein expression, reduced NADP+ /NADPH and GSH levels, and significantly increased ROS levels, thereby inducing oxidative stress.

CTZn impairs mitochondrial function, decreases ATP, levels, and induces G₂-phase arrest and apoptosis in CAL-27 cells. Therefore, it is an ideal drug for treating OSCC.