Papillary thyroid cancer (PTC) is the 8th most common cancer among women overall. Licorice contains over 300 active compounds, many of them with anti-cancer properties. Glycyrrhetinic acid (GA) is a major component of licorice. The aim of this study was to investigate the potential anti-proliferative effects of licorice and GA on PTC cell cultures. Licorice extract (LE) was produced from the root and tested on BCPAP and K1 cell lines, as well as GA and aldosterone. We used the MTT test to investigate the anti-proliferative activity, the wound healing test for the migratory activity, and finally, we analyzed cell cycle distribution, apoptosis, and oxidative stress after LE, GA, or aldosterone incubation. Both LE and GA reduced cell viability at 48 h and cell migration at 24 h in both PTC cultures. Aldosterone reduced cell migration only in K1 cells. LE and GA induced cell cycle arrest in the G0/G1 phase in the BCPAP cell line, while LE and aldosterone induced it in the K1 culture. GA but not LE increased the apoptosis rate in both cell lines, whereas LE but not GA increased oxidative stress in both cultures. This study presents the first evidence of the in vitro anti-proliferative and anti-migratory activity of LE and GA on PTC.
Keywords: glycyrrhetinic acid; licorice; mineralocorticoid; papillary thyroid cancer; thyroid; thyroid cancer.