[577] Up-Regulation of REG Is Associated with Human Gastric Adenocarcinoma: A Study of 216 Cases

W Feng, CD Truong, RE Brown, X Duan, W Li, J Xiao, K Xie, D Tan. 1The University of Texas MD Anderson Cancer Center, Houston, TX; The University of Texas Medical School, Houston, Houston, TX

Background: REG (PA28) is an activator of the 20S proteasome, which plays roles in apoptosis and mitotic progression. It has been shown to be overexpressed in poorly differentiated thyroid papillary carcinoma, colorectal cancer, and uterine leiomyosarcomas. In this study, we evaluated the expression and prognostic correlation of REG in gastric adenocarcinoma (GAC).
Design: Samples from 216 cases of gastric adenocarcinoma and 16 cases of non-neoplastic gastric tissues within formalin-fixed paraffin-embedded tissue microarray blocks were examined. Cases with preoperative treatment were excluded. Tissue microarrays were stained with REG antibody with colorectal cancer cells as positive control and internal stromal cells as negative control. The percent (0-100%) and intensity (1-3+) of unequivocal positive REG nuclear staining cells were determined and a composite score (CS: product of intensity and percent of positive cells, ranging 0 to 300) was calculated. REG expression was also correlated with patient survival data.
Results: GAC cases showed higher intensity and percent of cells with positive REG nuclear expression (average CS = 74), compared to non-neoplastic gastric controls (average CS = 40). 76% of GAC cases showed positive REG nuclear staining (intensity 1+). High REG overexpression cases showed better 10 year and 15 year survival (53% and 51% respectively) compared to low (rare 1+ staining) or negative REG expression cases (10 year and 15 year survival of 38% and 33% respectively), p<0.05.
Conclusions: The present study shows REG is over-expressed in gastric adenocarcinoma. It demonstrates that up-regulation of REG is associated better long term survival. These findings suggest that REG has a vital role in carcinogenesis and is a potential useful prognostic marker for GAC.
Category: Gastrointestinal

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 94, Monday Morning