To investigate the effects of Erianin on cell proliferation and apoptosis in human oral squamous cell carcinoma (OSCC) cells, providing a research foundation for the clinical treatment of OSCC.

Erianin was applied to OSCC cells (CAL27 and SCC9) at concentrations of 0, 2.5, 5, and 10 μmol/L. The inhibitory effect of Erianin on OSCC cell proliferation was evaluated using CCK-8 and soft agar colony formation assays. Western blotting (WB) was employed to analyze the expression levels of anti-apoptotic proteins B-cell lymphoma-extra large (Bcl-xL), B-cell lymphoma-2 (Bcl-2), myeloid cell leukemia-1 (Mcl-1), and apoptotic protein cleaved-Caspase 3 (c-Caspase 3) in OSCC cells. Caspase 3 activity was further assessed using a caspase 3 activity detection kit to examine the pro-apoptotic effect of Erianin in OSCC cells. Mcl-1 overexpression was induced in CAL27 cells via plasmid transfection, and the influence of Mcl-1 on the effects of Erianin in CAL27 cells was analyzed by WB and caspase 3 activity measurement. All animal experiments were approved by the Ethics Committee of Hunan Cancer Hospital. A CAL27 xenograft mouse model was established and randomly divided into two groups (n = 5): the treatment group received intraperitoneal injection of Erianin (25 mg/kg), while the control group was injected with phosphate-buffered saline (PBS) as the vehicle. Immunohistochemistry (IHC) was used to detect the expression levels of Ki67 and Mcl-1 in the tumor tissues.

Erianin inhibited the proliferation of CAL27 and SCC9 cells in a dose-dependent manner and downregulated the protein expression of Mcl-1, with minimal effects on Bcl-2 and Bcl-xL. Furthermore, Erianin induced apoptosis in OSCC cells, as evidenced by increased expression of c-Caspase 3 and enhanced caspase 3 activity (P＜0.001). Overexpression of Mcl-1 inhibited the Erianin-induced increase in c-Caspase 3 protein levels and caspase 3 activity. In vivo results were consistent with the in vitro findings. After Erianin treatment, CAL27 cell growth in nude mice was suppressed (P＜0.001), and the expression levels of the proliferation marker Ki67 and the anti-apoptotic protein Mcl-1 in the tumor tissues were downregulated (P＜0.001).

Erianin exhibits potent anti-tumor effects, effectively inhibiting the proliferation of OSCC cells and inducing apoptosis. The underlying mechanism may involve the downregulation of the pro-survival protein Mcl-1.