title: Honokiol inhibits melanoma stem cells by targeting notch signaling.
abstract: Melanoma is an aggressive disease with limited therapeutic options. Here, we determined the effects of honokiol (HNK), a biphenolic natural compound on melanoma cells and stemness. HNK significantly inhibited melanoma cell proliferation, viability, clonogenicity and induced autophagy. In addition, HNK significantly inhibited melanosphere formation in a dose dependent manner. Western blot analyses also demonstrated reduction in stem cell markers CD271, CD166, Jarid1b, and ABCB5. We next examined the effect of HNK on Notch signaling, a pathway involved in stem cell self-renewal. Four different Notch receptors exist in cells, which when cleaved by a series of enzymatic reactions catalyzed by Tumor Necrosis Factor-α-Converting Enzyme (TACE) and γ-secretase protein complex, results in the release of the Notch intracellular domain (NICD), which then translocates to the nucleus and induces target gene expression. Western blot analyses demonstrated that in HNK treated cells there is a significant reduction in the expression of cleaved Notch-2. In addition, there was a reduction in the expression of downstream target proteins, Hes-1 and cyclin D1. Moreover, HNK treatment suppressed the expression of TACE and γ-secretase complex proteins in melanoma cells. To confirm that suppression of Notch-2 activation is critical for HNK activity, we overexpressed NICD1, NICD2, and performed HNK treatment. NICD2, but not NICD1, partially restored the expression of Hes-1 and cyclin D1, and increased melanosphere formation. Taken together, these data suggest that HNK is a potent inhibitor of melanoma cells, in part, through the targeting of melanoma stem cells by suppressing Notch-2 signaling.
authors.affiliation: Departments of Surgery, The University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Kaushik
authors.affiliation: Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Anand
authors.initials: A
authors.lastname: Venugopal
authors.affiliation: Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Prabhu
authors.initials: P
authors.lastname: Ramamoorthy
authors.affiliation: Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: David
authors.initials: D
authors.lastname: Standing
authors.affiliation: Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Dharmalingam
authors.initials: D
authors.lastname: Subramaniam
authors.affiliation: Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Shahid
authors.initials: S
authors.lastname: Umar
authors.affiliation: Departments of Pathology, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Jensen
authors.affiliation: Departments of Surgery, The University of Kansas Medical Center, Kansas City, Kansas.|Departments of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Shrikant
authors.initials: S
authors.lastname: Anant
authors.affiliation: Departments of Surgery, The University of Kansas Medical Center, Kansas City, Kansas.|University of Kansas Cancer Center, Kansas City, Kansas.
authors.forename: Joshua M V
authors.initials: JM
authors.lastname: Mammen
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000072198:ADAM17 Protein; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D001713:Biphenyl Compounds / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019938:Cyclin D1 / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D051883:Receptor, Notch2 / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000072056:Transcription Factor HES-1; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D053829:Amyloid Precursor Protein Secretases; D051792:Basic Helix-Loop-Helix Proteins; D014408:Biomarkers, Tumor; D001713:Biphenyl Compounds; D019938:Cyclin D1; D018398:Homeodomain Proteins; D017705:Lignans; D051883:Receptor, Notch2; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; C497764:NOTCH2 protein, human; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols; C078493:HES1 protein, human; C000606462:ADAM17 protein, human
keywords: Cancer stem cells; Notch-1; Notch-2; autophagy; cell cycle arrest