Abstract 4503: The paracrine role of p53 in skin

Exposure to ultraviolet radiation (UVR) in sunlight activates both defensive and repair pathways in the skin. As the major cell type affected by UVR, keratinocytes coordinate critical aspects of the skin response. Molecularly, the transcription factor p53 is induced by UVR in keratinocytes leading to their cell death by apoptosis (peeling). p53 also stimulates the expression of paracrine melanocyte growth factors involved in tanning defined as increase in melanocyte proliferation and melanin synthesis. Here, we investigate the less defined role of p53 in tanning. For this, we use a mouse model that has high p53 levels in keratinocytes and presents with elevated melanocyte number and melanin production. Interestingly, loss of p53 in keratinocytes completely abrogates the hyperpigmentation phenotype. These data demonstrate in a powerful way the paracrine role of p53 expressed in keratinocytes on melanocyte behavior and function. Moreover, it provides an excellent tool to examine molecular and cellular changes that accompany the melanocyte response to sunburn. Sunburn increases melanoma risk in epidemiological studies. To elucidate the role of the p53 response in melanoma, we treated mice with “sunburning” doses of UVB and followed melanocyte proliferation and the expression of keratinocyte-induced melanocyte growth factors. We present our latest findings reinforcing the signs of cross-talk between keratinocytes and melanocytes which support a paracrine role for p53 expressed in keratinocyte on promoting melanocyte proliferation through the release of paracrine factors. Citation Format: Tamara Terzian, Nema Sobhani, Rohan Mylavarapu, Manale El Kharbili, Andrew Parker, Colleen Little, Ethan Krauspe, Neil Box. The paracrine role of p53 in skin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4503.