Author

Debra Smith

Date of Award

January 2011

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Michael Girardi

Subject Area(s)

Demography

Abstract

INVESTIGATING THE CONTRIBUTIONS OF LANGERHANS CELLS TO THE EPIDERMAL OXIDATIVE STRESS RESPONSE. Debra A. Smith, Julia Lewis, Renata Filler, Kseniya Golubets, Michael Girardi. Department of Dermatology, Yale University, School of Medicine, New Haven, CT.

Langerhans cells (LC) play an essential role in the development of skin cancer in a chemical carcinogenesis mouse model. To elucidate the mechanism of this effect, LC-deficient (Langerin-dipheria toxin A or human Langerin-diphtheria toxin receptor transgenic) mouse epidermis was compared to normal littermate controls (NLC) to assess whether levels of oxidative stress or DNA damage are affected by LC. Groups of mice were treated with either ultraviolet B (UVB) irradiation or 7,12-dimethylbenz(a)anthracene (DMBA)/tetradecanoylphorbol-13-acetate (TPA) carcinogens. Immunofluorecent staining with 8oxoguanine was used as a quantitative marker of oxidative stress and gammaH2AX staining was used to assess double stranded DNA breaks (DSB). Multiple consecutive high power fields assessed using a confocal microscope (Zeiss 510 META LSM) were quantified with ImageJ software (NIH).

These experiments represent a novel assay for assessing oxidative stress and DSB in epidermal sheets. LC-deficient epidermis exposed to UVB irradiation had higher levels of both oxidative stress (179.2±13.6 in LC-deficient, 96.3±27.6 in NLC; p=1.04x10-4) and DSB (40.86±3.6 in LC-deficient, 25.00±2.2 in NLC; p=0.005) than LC-intact controls, suggesting that LC may protect against UVB-induced oxidative stress and DNA damage. DMBA treated LC-deficient epidermis had a greater number of DSB compared to LC-intact controls (62.82±3.0 in LC-deficient, 81.15±3.8 in NLC; p=0.005), suggesting the LC promote DMBA-induced DNA damage. A more thorough understanding of the role of LC in carcinogenesis may have important implications in both cancer prevention and the development of potential immunotherapies.

Comments

This is an Open Access Thesis.

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