[804] MicroRNA Expression Analysis Suggests Genetic Similarity among Urachal Adenocarcinoma Morphologic Variants

Mei Lin Bissonnette, Thomas Stricker, Maria Tretiakova, Rafael Jimenez, Guliz A Barkan, Vikas Mehta, Sahussapont Sirintrapun, Gary Steinberg, Kevin White, Galdell Paner. University of Chicago, Chicago, IL; Mayo Clinic, Rochester, MN; Loyola University Medical Center, Maywood, IL; Wake Forest University, Winston-Salem, NC

Background: The vast majority of urachal carcinomas are adenocarcinomas, and several morphological variants of urachal adenocarcinoma have been described that include: mucinous, enteric, signet ring cell, not otherwise specified (NOS), and mixed subtypes. The clinical significance of these morphologic variants is not known. Recent immunohistochemical (IHC) studies on these subtypes have shown overlapping immunoprofiles. In this study, we analyzed the miRNA expression of these subtypes to determine if there is genetic distinction between these entities.
Design: Archival formalin-fixed paraffin embedded material of 12 urachal adenocarcinomas were selected from multiple institutions: 3 mucinous, 3 enteric, 2 signet ring, 2 mixed (enteric and mucinous) and 2 NOS subtypes. Each single subtype contained >50% of that particular subtype. The cases included 2 pure mucinous, 2 pure enteric, and 1 pure signet ring subtype. RNA was extracted, and the level of miRNA expression was determined for each sample using a 598 human miRNA code set with the nCounter miRNA Expression Assay (NanoString, Seattle, WA).
Results: Total RNA was extracted for all 12 cases. Of the 598 unique human miRNAs in the assay expression code set, 111 were highly expressed in all 12 samples. The remaining miRNAs were not well expressed in any of the samples. There were no significant differences in miRNA expression levels among any of the urachal adenocarcinoma morphological variants. Additionally, there were no significant differences in miRNA expression levels among the pure mucinous, pure enteric, and pure signet ring cases. The mixed subtypes did not show any significant miRNA expression level differences compared to the single or the pure subtypes.
Conclusions: Our study suggests that the morphological variants of urachal adenocarcinoma are genetically similar. These findings corroborate previous reports that showed immunophenotypic overlap of these tumor subtypes. The overlap in miRNA expression profiles among these morphological variants suggests a varied phenotypic manifestation of a single neoplastic process and suggests similarity in tumor biology.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 143, Monday Morning


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