title: p38delta Mitogen-activated protein kinase is essential for skin tumor development in mice.
abstract: Activating Ras mutations occur in a large portion of human tumors. Yet, the signaling pathways involved in Ras-induced tumor formation remain incompletely understood. The mitogen-activated protein kinase pathways are among the best studied Ras effector pathways. The p38 mitogen-activated protein kinase isoforms are important regulators of key biological processes including cell proliferation, differentiation, survival, inflammation, senescence, and tumorigenesis. However, the specific in vivo contribution of individual p38 isoforms to skin tumor development has not been elucidated. Recent studies have shown that p38delta, a p38 family member, functions as an important regulator of epidermal keratinocyte differentiation and survival. In the present study, we have assessed the effect of p38delta deficiency on skin tumor development in vivo by subjecting p38delta knockout mice to a two-stage 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate chemical skin carcinogenesis protocol. We report that mice lacking p38delta gene exhibited a marked resistance to development of 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate-induced skin papillomas, with increased latency and greatly reduced incidence, multiplicity, and size of tumors compared with wild-type mice. Our data suggest that the underlying mechanism for reduced susceptibility to skin carcinogenesis in p38delta-null mice involves a defect in proliferative response associated with aberrant signaling through the two major transformation-promoting pathways: extracellular signal-regulated kinase 1/2-activator protein 1 and signal transducer and activator of transcription 3. These findings strongly suggest an in vivo role for p38delta in promoting cell proliferation and tumor development in epidermis and may have therapeutic implication for skin cancer.
authors.affiliation: Division of Dermatology and Renal Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Schindler
authors.forename: Anna
authors.initials: A
authors.lastname: Hindes
authors.forename: Erin L
authors.initials: EL
authors.lastname: Gribben
authors.forename: Carole J
authors.initials: CJ
authors.lastname: Burns
authors.forename: Yan
authors.initials: Y
authors.lastname: Yin
authors.forename: Meei-Hua
authors.initials: MH
authors.lastname: Lin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Owen
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Longmore
authors.forename: Grace E
authors.initials: GE
authors.lastname: Kissling
authors.forename: J Simon C
authors.initials: JS
authors.lastname: Arthur
authors.forename: Tatiana
authors.initials: T
authors.lastname: Efimova
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002277:Carcinoma / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D049109:Cell Proliferation; D018450:Disease Progression; D004817:Epidermis / Q000378:metabolism / Q000473:pathology; D005260:Female; D011905:Genes, ras; D005838:Genotype; D006965:Hyperplasia / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D048292:Mitogen-Activated Protein Kinase 13 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009154:Mutation / Q000502:physiology; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D013755:Tetradecanoylphorbol Acetate
chemical_list: D048292:Mitogen-Activated Protein Kinase 13; D013755:Tetradecanoylphorbol Acetate