Ridd1, K., Davies1, R., Judah1, D., Riley1, J., Zhang1, S.D, Wolfreys2, A., Greaves1, P., Gant1, T., Smith1, A. 1MRC Toxicology Unit, University of Leicester, Leicester, UK, 2Safety Environmental Assurance Centre, Unilever, Colworth, Bedford, UK.

This study by researchers at the University of Leicester and Unilever’s Safety Environmental Assurance Centre (SEAC) demonstrated that MatTek’s EpiDerm human skin tissue equivalents can be kept in a viable state for up to 23 DAYS. The overall goal of this project, conducted by researchers at the University of Leicester and Unilever’s Safety Environmental Assurance Centre (SEAC), was to determine changes in gene expression occurring during the promotion phase of skin carcinogenesis in mice, and then to relate these to tumour development. The researchers then wanted to compare results using in vitro models treated in a similar manner to see if the in vivo responses were reproduced. These studies were based on the classical two-stage model of skin tumorigenesis using the carcinogen dimethylbenza[a]thracene (DMBA) as an initiating agent, followed by promotion with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Explant Findings: Both DMBA and TPA at high concentration (1000nM) reduced EpiDerm human tissue equivalent viability. Viability was unaltered by sub-toxic doses of DMBA followed by multiple applications of TPA. It was possible to maintain the EpiDerm cultures for up to 23 days while retaining good morphology. TPA irrespective of DMBA initiation caused aberrant differentiation of EpiDerm tissues manifested by the presence of nucleated cells within the cornified envelope. In summary, irrespective of the mode of initiation, researchers identified profiles of gene expression modulated during the promotion, and related to the tumour development, phase of tumorigenesis. These profiles may be applicable for use in predicting whether other compounds will function as tumour promoting agents. Skin carcinogenesis is a complex process not easily modeled in vitro. Cultured cell lines show differences in their response to promoting agents, and three dimensional skin explant models (EpiDerm) are good in vitro skin models to study epidermal toxicity, but their relatively short life span (23 days) compared to in vivo models (14 weeks) limits their use in tumorigenesis studies.


Carcinogenesis, EPI-100-NMM-HCF, ERK Signaling Pathway, EpiDerm, EpiDerm Viability, Epidermal Toxicity, Gene Expression, HaCaT Cells, Immunohistochemistry, In vitro, In vivo, MEK Pathway, Pam212 Cells, Primary Murine Keratinocytes, Skin Tumorigenesis, TNF-a

Materials Tested

Dimethylbenza[a]thracene (DMBA), Phorbol Ester 12-O-Tetradecanoylphorbol 13-acetate (TPA)

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