Context: Lucialdehyde B (LB), an effective triterpenoid isolated from Ganoderma lucidum (Leyss. ex Fr.) Karst. (Polyproraceae), exerts cytotoxic activity against nasopharyngeal carcinoma CNE2 cells.
Objective: To investigate the antiproliferative and pro-apoptotic effects of LB on CNE2 cells and explore its underlying mechanisms.
Materials and methods: LB concentrations of 5-40 μg/mL were used. Cell proliferation was determined using MTT, CFSE, and colony formation assays. LB-induced apoptosis and cell cycle arrest were measured by flow cytometry after 48-h LB treatments. Fluorescence microscopy and flow cytometry were performed to measure the alteration of MMP, mPTP opening, ROS level, and Ca2+ content in CNE2 cells. Western blotting was performed to evaluate the expression of mitochondrial apoptosis-related and Ras/ERK signaling proteins.
Results: IC50 values of LB against CNE2 cells for 24, 48, and 72 h were 25.42 ± 0.87, 14.83 ± 0.93, and 11.60 ± 0.77 μg/mL, respectively. The CFSE assay showed that the cell proliferation index was 12.70 in the LB treatment group and 31.44 in the control group. LB significantly reduced clonogenic capacity, promoted cell apoptosis and induced cell cycle arrest at the G2/M phase. Our observations also revealed that LB induced ROS and calcium aggregation, opening of mPTP, MMP reduction, upregulation of mitochondrial apoptosis-related protein expression and inhibition of Ras/ERK signaling cascades.
Discussion: LB suppresses proliferation and induces mitochondrial-dependent apoptosis in nasopharyngeal carcinoma CNE2 cells.
Conclusions: LB may have a potential use as a clinical drug candidate for nasopharyngeal carcinoma treatment.
Keywords: Ganoderma lucidum; apoptosis; cell proliferation; triterpenoid.