Research Interest

Solar radiation in the form of UVB is both an initiating and promoting agent. We have found that primary keratinocytes undergo a differentiation as well as an apoptotic response to UVB. To determine if these responses are altered during the course of immortalization, we examined markers of apoptosis in primary human keratinocytes (NHEK), as well as cells transduced with the E6 and E7 genes of HPV 16. NHEK, as well as early passage (p5) keratinocytes expressing HPV E6 plus E7 were both equally susceptible to UVB irradiation. In contrast, late passage (>p28; "immortal") E6/E7-expressing keratinocytes were exquisitely sensitive to UVB-induced apoptosis. To examine potential mechanisms for this differential response, we performed microarray analysis of UVB-treated and untreated samples for each of the three (primary, early passage, late passage) groups. The data revealed significant differences in a relatively small number of genes involved in cellular structure/adhesion, DNA repair, transcription, differentiation and apoptosis. Select gene expression levels were verified by RTPCR analysis, and protein levels were examined by Western analysis. We found that the Id3 was selectively induced in immortalized cells via ROS, and upregulated bax, leading to a mitochondrial pathway of apoptosis, while Id2 was upregulated in primary keratinocytes, leading to inhibition of differentiation and increased proliferation. In a graft system, Id2 contributes to tumorigenesis, mediated by its HLH domain. We are further examining the mechanisms by which Id2 and Id3 are induced and in turn exert their apoptotic and tumorigenic effects.

Projects

* Characterization and Modulation of Proteins Involved in Sulfur Mustard Vesication (2004-2007)
* Id Proteins in UV-Mediated Keratinocyte Apoptosis (2004-)
* Diagnosing DNA Mutations Using Mismatch Repair Enzymes (2004-)
* DNA-Based Lateral Flow Assay for Oncogenic Strains of Human Papilloma Viruses (2004-)