Copy Number Aberration in Canine Urothelial Carcinoma Detected by a Digital Polymerase Chain Reaction Assay.

Abstract

Urothelial carcinoma (UC) is the most common tumor affecting the urinary bladder of dogs. Protein overexpression of ErbB2 (the canine homolog of HER2) has been observed in dogs with UC. However, no study regardingcopy number aberration (CNA) is reported in dogs with UC. In this study, a digital PCR assay for detecting CNA of caninewas developed. DNA samples were isolated from 83 formalin-fixed, paraffin-embedded urinary bladder tissues (36 UC, 8 polypoid cystitis, and 39 normal) and 94 urinary sediments (54 UC, 30 nonneoplastic, and 10 normal). The copy number of canine chromosome 8 () was used as a control. In the urinary bladder tissues,CNA was detected in 12 of 36 (33%) UC, 2 of 8 (25%) polypoid cystitis, and 0 of 39 (0%) normal controls. In the urinary sediments,CNA was also detected in 19 of 54 (35%) UC; however, noCNA was detected in nonneoplastic diseases or normal controls. The sensitivity and specificity ofCNA in urinary sediment for the detection of UC were 35% and 100%, respectively. There was a positive correlation between the copy number ratios oftoin the urinary bladder tissues and urinary sediments. Our findings indicate that the digital PCR assay of urinary sediments may be a useful, noninvasive method for detectingCNA in dogs with UC.