A natural compound from magnolia (called “honokiol”) blocks a pathway for cancer growth that was previously considered “undruggable,” researchers have found. It also appears to be particularly effective against breast cancer. In one study, treatment of different human breast cancer cell lines with honokiol resulted in a time- and concentration-dependent growth inhibition in both estrogen receptor-positive and -negative breast cancer cell lines, as well as in drug-resistant breast cancer cell lines such as adriamycin-resistant and tamoxifen-resistant cell lines
 
Other studies have found honokiol to be particularly potent against tumors with activated Ras. One of the effects of Ras is to drive pumps that remove chemotherapy drugs from cancer cells. In breast cancer cell lines with activations in Ras family genes, honokiol appears to prevent Ras from turning on an enzyme called phospholipase D. It also has similar effects in lung and bladder cancer cells in the laboratory. Phospholipase D provides what have come to be known as “survival signals” in cancer cells, allowing them to stay alive when ordinary cells would die.
 
References
 
“Honokiol Suppresses Survival Signals Mediated by Ras-Dependent Phospholipase D Activity in Human Cancer Cells.” Clinical Cancer Research 14, 4267-4274, July 1, 2008. doi: 10.1158/1078-0432.CCR-08-0102. Avalon Garcia, Yang Zheng, Chen Zhao, Alfredo Toschi, Judy Fan, Natalie Shraibman, H. Alex Brown, Dafna Bar-Sagi, David A. Foster and Jack L. Arbiser ###
 
Eur J Pharmacol. 2008 Jun 12. Anti-tumor effect of honokiol alone and in combination with other anti-cancer agents in breast cancer. Liu H, Zang C, Emde A, Planas-Silva MD, Rosche M, Kühnl A, Schulz CO, Elstner E, Possinger K, Eucker J.