[991] Expression of PAX8 in Normal and Neoplastic Tissues: A Comprehensive IHC Analysis

D Tacha, L Cheng, D Zhou, RL Henshall-Powell. Biocare Medical, Concord, CA; Indiana Univ School of Med, Indianapolis, IN

Background: PAX genes are a family of cell-lineage transcription factors that play a role during organogenesis and are regulatory proteins expressed embryonic or neoplastic cells of the same lineage. These proteins are required for cell growth and differentiation in embryonic tissues and in adult tissues in specific cell-lineage neoplastic tissues. Other transcription factors in this family include TTF-1 and CDX2. PAX8 is a nephric-lineage transcription factor and can be expressed in kidney, thyroid and ovarian cancers. Little is known about the specificity of PAX8 in various neoplastic tumors. This study examines the IHC expression in multiple normal and neoplastic tissues.
Design: Tissue microarrays (TMA) of various normal and neoplastic tissues were constructed from archival tissues. The patient information containing age, sex, diagnosis, stage, grade and IHC staining was analyzed. TMAs were deparaffinized in the usual way, and antigen retrieval was performed using a pressure cooker. TMA tissue cores were incubated with PAX8 for 30 minutes, followed by visualization (DAB) using a biotin-free detection system.
Results: PAX expression was positive in renal cell carcinoma (90%), ovarian cancers (82%), thyroid cancers (90%) and endometrial carcinomas (81%). In lung cancer, PAX8 staining was found in only 1 case (1+ staining). The majority of other cancers were 100% negative (Table 1). PAX 8 was also seen in normal tonsil and lymph node. Expression appeared to be confined to B-cells and/or cells of B-cell lineage.

Table 1
DiagnosisTotal CasesPositive% Positive
Renal Cell Carcinoma12211090%
Ovarian Cancer24420182%
Endometrial Cancer13410881%
Thyroid Tumors10990%
Neuroendocrine Tumors1517%
Cervical Cancer7374%
Pancreatic Cancer23313%
Bladder Cancer7568%
Lung Cancer10011%
Colon Cancer10000%
Breast Cancer10000%
Prostate Cancer3500%
Liver Cancer3600%
Stomach Cancer600%
Esophageal Cancer600%
Soft Tissue Tumor2125%
FDA Normal Tissues33*13%
*Normal Prostate

Conclusions: PAX8 is a very specific and sensitive marker for renal cell and ovarian carcinomas, and may prove to be equally sensitive for thyroid and endometrial cancers. In this study, PAX8 specificity has been evaluated in over 1000 cases; 21 different cancers and their subtypes, and 33 different normal tissues.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 133, Tuesday Morning


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