The structural integrity of the human epidermis crucially depends on attachment of basal keratinocytes to the basement membrane through integrin receptors. Integrin ?? heterodimers respond to a variety of extracellular matrix cues to promote adhesion and epidermal stratification. Several integrin subunits are aberrantly over- expressed over the course of squamous cell carcinoma (SCC) progression, leading to altered subunit heterodimerization and intracellular signaling that can promote tumor growth and invasion. While some integrin subunits are known to contribute to both skin homeostasis and SCC, the functional roles for most subunits in skin are unknown. The Ridky lab has developed a novel, three-dimensional human skin model that is ideal for the study of integrin signaling. We reconstitute skin in organotypic culture (OTC), using primary human dermal and epidermal cells and native human dermis with a functional and intact basement membrane zone. The primary keratinocytes used in this skin model can be transduced with oncogenes to generate invasive neoplastic tissue. Additionally, this OTC skin can be grafted onto an immunocompromised mouse to generate viable human skin or SCC tumors in vivo. Using this model, I have shown for the first time that integrin ?v is necessary for basal keratinocyte proliferation and epidermal stratification. I have also shown that integrin ?v is essential for squamous cell carcinoma invasion through the basement membrane. The experiments described in this proposal aim to elucidate the specific signaling mechanisms that mediate this loss of skin proliferation (Aim 1) and SCC invasion (Aim 2) seen upon integrin ?v knock down in OTC and in vivo. In cultured cells, integrin ?v knock down correlates with a decrease in EGFR, TGF? and FAK activation.
Aims 1 A and 2A seek to uncover whether these pathways functionally mediate the loss of epidermal proliferation and stratification and SCC invasion upon integrin ?v knock down. This will be done by functionally rescuing activation of these pathways using lentivirus transduction, and determining whether the phenotype is reversed. Experiments proposed in Aims1B and 2B will determine the specific ? binding partners that complex with integrin ?v to mediate its role in both normal skin and neoplasia. This will be done by performing co- immunoprecipitation in cultured cells and tissues, and knocking down expression of each ? binding partner to determine if this can phenocopy loss of integrin ?v. Two of integrin ?v's ? binding partners-?1 and ?6-are up-regulated in a similar model of SCC, suggesting a heterodimeric switch during the course of tumor progression. My proposed work will determine if this heterodimeric switch exists, and if specific ?v heterodimers are viable therapeutic targets.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
1F31CA186446-01
Application #
8716324
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Schmidt, Michael K
Project Start
2014-06-01
Project End
2017-05-31
Budget Start
2014-06-01
Budget End
2015-05-31
Support Year
1
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Dermatology
Type
Schools of Medicine
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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Duperret, Elizabeth K; Natale, Christopher A; Monteleon, Christine et al. (2016) The integrin αv-TGFβ signaling axis is necessary for epidermal proliferation during cutaneous wound healing. Cell Cycle 15:2077-86
Duperret, Elizabeth K; Dahal, Ankit; Ridky, Todd W (2015) Focal-adhesion-independent integrin-αv regulation of FAK and c-Myc is necessary for 3D skin formation and tumor invasion. J Cell Sci 128:3997-4013
McNeal, Andrew S; Liu, Kevin; Nakhate, Vihang et al. (2015) CDKN2B Loss Promotes Progression from Benign Melanocytic Nevus to Melanoma. Cancer Discov 5:1072-85
Duperret, Elizabeth K; Oh, Seung Ja; McNeal, Andrew et al. (2014) Activating FGFR3 mutations cause mild hyperplasia in human skin, but are insufficient to drive benign or malignant skin tumors. Cell Cycle 13:1551-9
Dews, Michael; Tan, Grace S; Hultine, Stacy et al. (2014) Masking epistasis between MYC and TGF-β pathways in antiangiogenesis-mediated colon cancer suppression. J Natl Cancer Inst 106:dju043
Duperret, Elizabeth K; Ridky, Todd W (2014) Kindler syndrome in mice and men. Cancer Biol Ther 15:1113-6