| 2392 Circadian Clock Protein Per-1 Is Downregulated in Oral Cancer | ||
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K.B. JONES, S. LIM, B.L. SCHMIDT, and R. JORDAN, University of California - San Francisco, USA Background: Endogenous biological rhythms have been demonstrated at all biological levels, from yeast and nucleated unicells to man, and at all levels of biological organization. Of the established rhythm periods, the circadian rhythm (24-hour period) has been most thoroughly investigated. We previously documented that normal oral epithelial cells show a distinct circadian 24-hour rhythm. Several gene products that regulate the body's 24-hour circadian rhythm have altered expression in tumors, such as per-1, which from in vitro assays share many biological properties with tumor suppressor genes. Objective: To determine changes in per-1 protein expression in oral precancer and squamous cell carcinoma (SCC). Methods: Formalin-fixed, paraffin embedded tissue sections of normal oral epithelium (n=4), mild dysplasia (n=9), moderate dysplasia (n=8), severe dysplasia (n=7), and oral SCC (n=10) were stained by immunohistochemistry for expression of per-1 protein. Sections were scored determining the number of positive and negative cells in at least 200 cells and results expressed as a proportion of total positive cells for each disease category. Results: Per-1 protein expression was identified in the nuclei of epithelial cells. In normal samples, positive cells were restricted to the basal and parabasal layers. In dysplasia cases there was more widespread expression in all layers. The proportion of cells for each disease category (± 95% CI) were as follows: Normal Oral Epithelium: 60.78% ± 4.51% Mild Dysplasia: 66.02% ± 2.91% Moderate Dysplasia: 67.43% ± 3.32% Severe Dysplasia: 68.11% ± 5.25% Oral SCC: 50.72% ± 4.77% Conclusions: We report for the first time expression of per-1 in oral dysplasias and oral SCC. There was significantly reduced expression of per-1 protein in oral SCC compared to normal epithelial controls and dysplasias. Per-1 may play a role in oral carcinogenesis. Support: NIDCR K12 DE14609, NIDCR DE017249-01, NCI CA095231 | ||
| Seq #240 - Premalignant Oral Lesions and Oral Cancer 3:30 PM-4:45 PM, Friday, March 23, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J | ||
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