[1041] Expression of S100P in Benign Endometrium and Endometrial Adenocarcinoma.

Wei Feng, Qi Shen, Robert E Brown, Xiuzhen Duan. University of Texas Medical School, Houston

Background: S100P is a 95-amino acid isoform of the S100 protein family with restricted cellular distribution, first purified from placenta. It activates ERK and NF-kB pathways via the receptor for advanced glycation end-product to promote cellular proliferation and survival. Its expression has been reported in breast, prostate, lung and gastrointestinal malignancies. Recent complementary DNA studies of human endometrium showed S100P is expressed in the postovulatory endometrium. The expression of S100P in endometrial adenocarcinoma (EAC) is largely unknown. We evaluated the expression of S100P in EAC, proliferative endometrium (PE), and secretory endometrium (SE) in this study.
Design: Biopsy and hysterectomy specimens were retrieved from the Department of Pathology archives at Lyndon B. Johnson General Hospital. and a formalin-fixed, paraffin-embedded tissue microarray containing 31 EAC, 29 PE, and 21 SE was constructed. Immunohistochemistry was performed using a mouse monoclonal antibody against human S100P (1:20, R&D Systems, Inc. Minneapolis, MN, USA). S100P expression was semi-quantified by light microscopy regarding staining pattern (cytoplasmic vs nuclear), percent of staining cells (0-100%) and intensity of staining (0-3+). Positive staining is defined as at least 1+ concurrent nuclear and cytoplasmic staining. Cytoplasmic staining alone is regarded as negative.
Results: S100P is expressed predominantly within the nucleus but is also present within the cytoplasm. Minority of EAC (3/31, 9.7%) showed strong (2-3+) and focal to patchy (3 to 50% of cells) S100P staining. Majority of SE (17/21, 81%) showed positive (1-3+) and patchy to diffuse (30 to 90% of cells) S100P staining. All mid to late secretory endometrium (≥ day 20) showed strong and diffuse S100P staining and most (4/6) early secretory endometrium (< day 20) showed negative S100P staining. Minority of PE (5/29, 17%) showed positive (1-2+) and variably distributed (5 to 80% of cells) S100P staining. EAC showed statically significant lower frequency of positive S100P expression compared to SE (P <.001) but not compared to PE (P = .47); and SE showed statically significant higher frequency of positive S100P expression compared to PE (P <.001) by Fisher's exact test.
Conclusions: Majority of EAC do not show S100P overexpression but S100P expression is consistently present within benign SE. These findings indicated S100P expression may be utilized to differentiate difficult cases of EAC and SE with highly complex glandular architecture. Furthermore, S100P immunohistochemical staining may also be an adjunct study in endometrium dating for infertility workup.
Category: Gynecologic & Obstetrics

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 142, Wednesday Afternoon


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