title: Anti-tumor effect of honokiol alone and in combination with other anti-cancer agents in breast cancer.
abstract: Honokiol, an active component isolated and purified from Chinese traditional herb magnolia, was demonstrated to inhibit growth and induce apoptosis of different cancer cell lines such as human leukaemia, colon, and lung cancer cell lines; to attenuate the angiogenic activities of human endothelial cells in vitro; and to efficiently suppress the growth of angiosarcoma in nude mice. In this study, we have demonstrated that 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. The inhibition of growth was associated with a G1-phase cell cycle arrest and induction of caspase-dependent apoptosis. The effects of honokiol might be reversely related to the expression level of human epidermal growth receptor 2, (HER-2, also known as erbB2, c-erbB2) since knockdown of her-2 expression by siRNA significantly enhanced the sensitivity of the her-2 over-expressed BT-474 cells to the honokiol-induced apoptosis. Furthermore, inhibition of HER-2 signalling by specific human epidermal growth receptor 1/HER-2 (EGFR/HER-2) kinase inhibitor lapatinib synergistically enhanced the anti-cancer effects of honokiol in her-2 over-expressed breast cancer cells. Finally, we showed that honokiol was able to attenuate the PI3K/Akt/mTOR (Phosphoinositide 3-kinases/Akt/mammalian target of rapamycin) signalling by down-regulation of Akt phosphorylation and upregulation of PTEN (Phosphatase and Tensin homolog deleted on chromosome Ten) expression. Combination of honokiol with the mTOR inhibitor rapamycin presented synergistic effects on induction of apoptosis of breast cancer cells. In conclusion, honokiol, either alone or in combination with other therapeutics, could serve as a new, promising approach for breast cancer treatment.
authors.affiliation: Department of Oncology and Hematology, University Hospital Charité, Humboldt University of Berlin, Berlin, Germany.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Liu
authors.forename: Chuanbing
authors.initials: C
authors.lastname: Zang
authors.forename: Anna
authors.initials: A
authors.lastname: Emde
authors.forename: Maricarmen D
authors.initials: MD
authors.lastname: Planas-Silva
authors.forename: Marleen
authors.initials: M
authors.lastname: Rosche
authors.forename: Andrea
authors.initials: A
authors.lastname: Kühnl
authors.forename: Carsten-Oliver
authors.initials: CO
authors.lastname: Schulz
authors.forename: Elena
authors.initials: E
authors.lastname: Elstner
authors.forename: Kurt
authors.initials: K
authors.lastname: Possinger
authors.forename: Jan
authors.initials: J
authors.lastname: Eucker
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000008:administration & dosage* / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D000077341:Lapatinib; D017705:Lignans / Q000008:administration & dosage* / Q000494:pharmacology; D031566:Magnolia / Q000737:chemistry; D008516:Medicine, Chinese Traditional; D011799:Quinazolines / Q000008:administration & dosage; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000008:administration & dosage; D013997:Time Factors; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D001713:Biphenyl Compounds; D000077341:Lapatinib; D017705:Lignans; D011799:Quinazolines; D020123:Sirolimus; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols