Honokiol Suppresses Cell Proliferation and Tumor Migration through ROS in Human Anaplastic Thyroid Cancer Cells.

[BACKGROUND] Honokiol is a natural polyphenolic compound extracted from Magnolia officinali, which is commonly used material in Chinese herbal medicine, has a variety of biological functions, including anti-tumor, anti-oxidant, anti-inflammation, anti-microbial and anti-allergy. Although honokiol has numerous beneficial effects on human diseases, the underlying mechanisms of tumor metastasis are still unclear. Previously, we reported that honokiol suppresses thyroid cancer cell proliferation with cytotoxicity through cell cycle arrest, apoptosis, and dysregulation of intracellular hemostasis. Herein, we hypothesized that the antioxidant effect of honokiol might play a critical role in thyroid cancer cell proliferation and migration.

[METHODS] The cell viability assays, cellular reactive oxygen species (ROS) activity, cell migration, and immunoblotting were performed after cells were treated with honokiol.

[RESULTS] Based on this hypothesis, we first demonstrated that honokiol suppresses cell proliferation in two human anaplastic thyroid carcinoma (ATC) cell lines, KMH-2 and ASH-3, within a dosage- and time-dependent manner by cell counting kit-8 (CCK-8) assay. Next, we examined that honokiol induced ROS activation and could be suppressed by pre-treated with an antioxidant agent, N-acetyl-l-cysteine (NAC). Furthermore, the honokiol suppressed cell proliferation can be rescued by pre-treated with NAC. Finally, we demonstrated that honokiol inhibited ATC cell migration by modulating epithelial-mesenchymal transition (EMT)-related markers by Western blotting.

[CONCLUSION] Taken together, we provided the potential mechanism for treating ATC cells with honokiol, which significantly suppresses tumor proliferation and inhibits tumor metastasis in vitro through reactive oxygen species (ROS) induction.