Wnt Family Member 9b (Wnt9b) Is a Sensitive and Specific Marker for Triple-negative Breast Carcinoma Including Metaplastic Carcinoma.

Abstract

Wnt9b was recently identified as a highly sensitive and specific marker for breast carcinomas. Due to the limited number of triple-negative breast carcinomas (TNBCs) in previous study, we further explored Wnt9b's utility in breast carcinoma, especially in TNBCs including metaplastic carcinomas. We systematically evaluated Wnt9b expression on tissue microarrays (TMAs) from 413 breast carcinomas, 208 urothelial carcinomas, 102 endometrial carcinomas, 109 cholangiocarcinomas, 192 ovarian carcinomas, 48 lung adenocarcinomas, 69 colorectal adenocarcinomas, and 78 melanomas, and whole tissue section (WTS) from 20 human epidermal growth factor receptor 2-positive, 34 nonmetaplastic TNBCs, and 67 invasive metaplastic carcinomas. The results showed Wnt9b was highly expressed in breast carcinomas (91% on TMA and 98% on WTS) and in nonmetaplastic TNBCs (91% on TMA and 97% on WTS), but almost completely negative in other tested tumor types. Wnt9b was also highly expressed in metaplastic carcinomas (80%), significantly higher than GATA3 (56%) and SOX10 (48%), but slightly lower than TRPS1 (90%). In summary, our results demonstrate that Wnt9b is a highly sensitive marker for breast carcinomas, including TNBCs and metaplastic carcinomas. Further, we compared its utility with other breast markers including TRPS1, GATA3, and SOX10 in metaplastic carcinomas.