A Newly Developed Anti-Uroplakin II Antibody with Increased Sensitivity in Urothelial Carcinoma of the Bladder
Laura Hoang, Weimin Qi, Ryan Bremer, Joseph Chu, Thomas Haas, David Tacha, Liang Cheng. Biocare Medical, LLC, Concord, CA; Mercy Health System, Janesville, WI; Indiana University School of Medicine, Indianapolis, IN
Background: Uroplakin II (UPII) is a 15 kDa protein component of urothelial plaques which enhance the permeability barrier of the urothelium. Studies have shown UPII mRNA to be expressed in both bladder cancer tissues and peripheral blood of patients with primary and metastatic urothelial carcinoma (UC) of the bladder. Little is known about the protein expression of UPII in UC of the bladder, possibly due to the absence of a commercially available anti-UPII antibody. Pathologists have used UPIII [AU1] to establish urothelial origin of the tumor; however use of AU1 is limited due to its poor sensitivity. A clear need exists for a sensitive and specific urothelial biomarker for use in UC diagnosis. Following previous development of a sensitive anti-UPIII antibody [BC17], this study evaluated the sensitivity of a newly developed anti-UPII antibody [BC21] in UC of the bladder.
Design: The monoclonal mouse UPII antibody [BC21] was developed by immunizing Balb/C mice with a recombinant human UPII protein corresponding to amino acids 26-155. Monoclonal mouse UPII and UPIII antibodies were optimized for staining FFPE bladder cancer tissues, using an HRP-polymer detection system and visualization with DAB.
Results: In all grades, the UPII antibody exhibited an increased sensitivity (46/59, 78%) compared to the UPIII antibody (33/59, 56%) in cases of UC (p-value<0.001) [Table 1]. The UPII antibody provided increased staining intensity, across a greater proportion of tumor cells, than UPIII. In addition, the UPII antibody was found to be highly specific when evaluated in various normal and neoplastic tissues, including prostate cancer and renal cell carcinoma. As expected, the urotheliums of bladder and ureter were the only normal tissues to stain positive with UPII.
|Antibody||Grade||# of cases||Positive||% Positive|
|UPII [BC21]||Grades I, II & III||59||46||78%|
|UPIII [BC17]||Grades I, II & III||59||33||56%|
|UPII [BC21]||Grade II||35||27||77%|
|UPIII [BC17]||Grade II||35||19||54%|
|UPII [BC21]||Grade III||11||7||64%|
|UPIII [BC17]||Grade III||11||7||64%|