Honokiol Is More Potent than Magnolol in Reducing Head and Neck Cancer Cell Growth

The efficacy of treatment of head and neck squamous cell carcinoma (HNSCC) patients is still unsatisfactory, and there is an ongoing search for novel therapies. Locoregionally advanced HNSCC cases, which frequently require combined surgery and chemoradiotherapy, are especially difficult to treat. Natural compounds, like Magnolia-derived lignans-honokiol (HON) and magnolol (MAG)-can reduce cancer cell growth but retain a good safety profile and thus may show benefit as adjuvant therapeutics. The aim of this study was to evaluate the anti-cancer effects of HON and MAG in HNSCC cell lines and compare their effects between cisplatin-sensitive and cisplatin-tolerant cells. Cell viability was evaluated in FaDu and SCC-040 cells growing as monolayers and as spheroids. The effect of HON and MAG on the cell cycle, apoptosis, and gene expression was compared between wild-type FaDu cells and cisplatin persister FaDu cells. We observed that HON and MAG were more potent in reducing cell viability in cisplatin persister FaDu cells, although this effect was not directly followed by increased rates of apoptosis. Thus, HON's and MAG's capacity to affect cisplatin persister cells needs further studies. In general, we observed that HON exerted stronger cytotoxic effects than MAG in HNSCC cells, and the difference in their anti-cancer activity was especially pronounced in cells cultured in 3D.