title: Keratin-6 driven ODC expression to hair follicle keratinocytes enhances stemness and tumorigenesis by negatively regulating Notch.
abstract: Over-expression of ornithine decarboxylase (ODC) is known to be involved in the epidermal carcinogenesis. However, the mechanism by which it enhances skin carcinogenesis remains undefined. Recently, role of stem cells localized in various epidermal compartments has been shown in the pathogenesis of skin cancer. To direct ODC expression in distinct epidermal compartments, we have developed keratin 6 (K6)-ODC/SKH-1 and keratin 14 (K14)-ODC/SKH-1 mice and employed them to investigate the role of ODC directed to these epidermal compartments on UVB-induced carcinogenesis. K6-driven ODC over-expression directed to outer root sheath (ORS) of hair follicle was more effective in augmenting tumorigenesis as compared to mice where K14-driven ODC expression was directed to inter-follicular epidermal keratinocytes. Chronically UVB-irradiated K6-ODC/SKH-1 developed 15±2.5 tumors/mouse whereas K14-ODC/SKH-1 developed only 6.8±1.5 tumors/mouse. K6-ODC/SKH-1 showed augmented UVB-induced proliferation and much higher pro-inflammatory responses than K14-ODC/SKH-1 mice. Tumors induced in K6-ODC/SKH-1 were rapidly growing, invasive and ulcerative squamous cell carcinoma (SCC) showing decreased expression of epidermal polarity marker E-cadherin and enhanced mesenchymal marker, fibronectin. Interestingly, the number of CD34/CK15/p63 positive stem-like cells was significantly higher in chronically UVB-irradiated K6-ODC/SKH-1 as compared to K14-ODC/SKH-1 mice. Reduced Notch1 expression was correlated with the expansion of stem cell compartment in these animals. However, other signaling pathways such as DNA damage response or mTOR signaling pathways were not significantly different in tumors induced in these two murine models suggesting the specificity of Notch pathway in this regard. These data provide a novel role of ODC in augmenting tumorigenesis via negatively regulated Notch-mediated expansion of stem cell compartment.
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
authors.forename: Aadithya
authors.initials: A
authors.lastname: Arumugam
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Weng
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
authors.forename: Sandeep C
authors.initials: SC
authors.lastname: Chaudhary
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
authors.forename: Farrukh
authors.initials: F
authors.lastname: Afaq
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA; Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Elmets
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA; Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Electronic address: mathar@uab.edu.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Athar
mesh_terms: D000818:Animals; D063646:Carcinogenesis; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D005260:Female; D018859:Hair Follicle / Q000378:metabolism; D053547:Keratin-14 / Q000378:metabolism; D053553:Keratin-6 / Q000494:pharmacology*; D015603:Keratinocytes / Q000378:metabolism; D051379:Mice; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D051880:Receptors, Notch / Q000096:biosynthesis*; D012878:Skin Neoplasms / Q000209:etiology / Q000473:pathology
chemical_list: D053547:Keratin-14; D053553:Keratin-6; C507446:Krt14 protein, mouse; D051880:Receptors, Notch; D009955:Ornithine Decarboxylase
keywords: EMT; Hair follicle; Notch; ODC; Stem cell; UVB
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