NKX3.1 [MD149R]

NKX-3.1 is a protein found in humans and is encoded by the NKX3-1 gene located on chromosome 8. The homeodomain containing transcription factor NKX3A is a putative prostate tumor suppressor that is expressed in a largely prostate-specific and androgen-regulated manner. NKX3.1 protein has been found to be positive in the vast majority of primary prostatic adenocarcinomas. A recent study showed that NKX3.1 staining was highly sensitive and specific for high-grade prostatic adenocarcinomas. The sensitivity for identifying metastatic prostatic adenocarcinomas overall was 98.6% (68/69 cases positive) for NKX3.1, and 94.2% (65/69 cores positive) for PSA. The specificity of NKX3.1 was 99.7% (1/349) in various cancers. NKX3.1 stains nuclei in both normal and prostate cancer; thus providing a robust stain that is easy-to-interpret, similar to other transcription factors such as TTF-1 or CDX2. In the appropriate clinical setting, the addition of IHC staining for NKX3.1, along with other prostate-restricted markers, may prove to be a valuable adjunct to definitively determine prostatic origin in poorly differentiated metastatic carcinomas. NKX3.1 used in combination with ERG monoclonal antibody, may represent one of the most sensitive and specific markers for identifying tumors of prostatic origin.