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.
|Diagnosis||Total Cases||Positive||% Positive|
|Renal Cell Carcinoma||122||110||90%|
|Soft Tissue Tumor||21||2||5%|
|FDA Normal Tissues||33||*1||3%|