Honokiol inhibits growth and induces apoptosis in multidrug-sensitive and -resistant cells.

<p>(<b>a, b</b>) Growth inhibition effect of paclitaxel and p-gp expression in KB-3-1, KB-8-5, KB-C1 and KB-V1 cells. The IC₅₀ values of paclitaxel in drug resistant KB-8-5, KB-C1 and KB-V1 cells were increased by 16-, 117-, and 4000-fold respectively when compared to parental KB-3-1 cells. (<b>c, d</b>) Growth inhibition effect of honokiol in KB-3-1, KB-8-5, KB-C1 and KB-V1 cells. The IC₅₀ values of honokiol in drug resistant KB-8-5, KB-C1 and KB-V1 cells were similar to that in parental KB-3-1 cells. (<b>e</b>) Honokiol induces apoptosis in KB cells. KB-3-1 and KB-8-5 cells were treated with 5, 10, 15 µg/ml of honokiol for 24, 48, and 72 h. KB-C1 and KB-V1 cells were treated with honokiol for 48 h. Apoptosis was measured by annexin V-phycoerythrin staining. *indicates statistically significant p values (*,versus control, p<0.05; **, versus 5 µg/ml, p<0.05).