Regulatory Effect of 4-O-Methylhonokiol on TGF-β1-Induced Cell Cycle Arrest in Human Keratinocyte Cell Line (HaCaT)

The study conducted 12 years ago investigated the hair-growth promoting effects of 4-O-methylhonokiol, a compound from Magnolia Officinalis, on the Transforming growth factor-β (TGF-β) signal pathway in HaCaT cells. The researchers found that pre-treatment with 4-O-methylhonokiol decreased the expression of TGF-β1-induced p21 and attenuated the nuclear translocation of Smad2/3, Smad4, and Sp1 activation. It also reduced TGF-β1-induced activation of ERK and inhibited TGF-β1-induced reactive oxygen species (ROS) production, suppressing mRNA expression of NOX4. These findings suggested that the hair-growing activity of 4-O-methylhonokiol might be related to its modulatory action on TGF-β-induced cell cycle arrest and ROS production.