title: Ingenol Mebutate Signals via PKC/MEK/ERK in Keratinocytes and Induces Interleukin Decoy Receptors IL1R2 and IL13RA2.
abstract: Squamous cell carcinoma (SCC) is the second most common human skin cancer and the second leading cause of skin cancer-related death. Recently, a new compound, ingenol mebutate, was approved for treatment of actinic keratosis, a precursor of SCC. As the mechanism of action is poorly understood, we have further investigated the mechanism of ingenol mebutate-induced cell death. We elucidate direct effects of ingenol mebutate on primary keratinocytes, patient-derived SCC cells, and a SCC cell line. Transcriptional profiling followed by pathway analysis was performed on ingenol mebutate-treated primary keratinocytes and patient-derived SCC cells to find key mediators and identify the mechanism of action. Activation of the resulting pathways was confirmed in cells and human skin explants and supported by a phosphorylation screen of treated primary cells. The necessity of these pathways was demonstrated by inhibition of certain pathway components. Ingenol mebutate inhibited viability and proliferation of all keratinocyte-derived cells in a biphasic manner. Transcriptional profiling identified the involvement of PKC/MEK/ERK signaling in the mechanism of action and inhibition of this signaling pathway rescued ingenol mebutate-induced cell death after treatment with 100 nmol/L ingenol mebutate, the optimal concentration for the first peak of response. We found the interleukin decoy receptors IL1R2 and IL13RA2 induced by ingenol mebutate in a PKC/MEK/ERK-dependent manner. Furthermore, siRNA knockdown of IL1R2 and IL13RA2 partially rescued ingenol mebutate-treated cells. In conclusion, we have shown that ingenol mebutate-induced cell death is mediated through the PKCδ/MEK/ERK pathway, and we have functionally linked the downstream induction of IL1R2 and IL13RA2 expression to the reduced viability of ingenol mebutate-treated cells.
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Sandra N
authors.initials: SN
authors.lastname: Freiberger
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Phil F
authors.initials: PF
authors.lastname: Cheng
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Guergana
authors.initials: G
authors.lastname: Iotzova-Weiss
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Johannes
authors.initials: J
authors.lastname: Neu
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Qinxiu
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Dziunycz
authors.affiliation: LEO Pharma A/S, Ballerup, Denmark.
authors.forename: John R
authors.initials: JR
authors.lastname: Zibert
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Dummer
authors.affiliation: LEO Pharma A/S, Ballerup, Denmark.
authors.forename: Kresten
authors.initials: K
authors.lastname: Skak
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland.
authors.forename: Mitchell P
authors.initials: MP
authors.lastname: Levesque
authors.affiliation: Department of Dermatology, University Hospital Zurich, Switzerland. Hofbauer@usz.ch.
authors.forename: Günther F L
authors.initials: GF
authors.lastname: Hofbauer
mesh_terms: D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D016000:Cluster Analysis; D004224:Diterpenes / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D053663:Interleukin-13 Receptor alpha2 Subunit / Q000378:metabolism*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D053574:Receptors, Interleukin-1 Type II / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C486592:3-ingenyl angelate; D004224:Diterpenes; D053663:Interleukin-13 Receptor alpha2 Subunit; D053574:Receptors, Interleukin-1 Type II; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases