CD146 protein in prostate cancer: revisited with two different antibodies

CD146 is a potentially metastasis promoting cell adhesion molecule and its expression has been described in various solid tumours. We aimed to evaluate the expression of CD146 in prostate cancer by immunohistochemistry in a clinically characterised study cohort to evaluate its prognostic properties.

We evaluated the CD146 protein expression using a polyclonal and a monoclonal antibody on 169 clinico-pathologically characterised cases. Statistical analyses were applied to test for correlations and diagnostic and prognostic associations.

CD146 detection with the polyclonal antibody revealed marked differential expression between tumour and normal tissue and was also a significant marker for shortened PSA relapse free survival. The monoclonal CD146 antibody demonstrated a weaker epithelial signal, which was significantly correlated with that of the polyclonal antibody, but revealed no prognostic value. However, the Western blot of the polyclonal antibody displayed a clearly reduced specificity.

Evaluation of protein expression can be highly dependent on the primary antibody employed. A credible evaluation of antibody specificity is crucial to prove the validity of protein expression studies. The immunoreactivity of the polyclonal CD146 antibody (Abcam, ab28360) is prognostic of PSA-relapse in prostate cancer patients, although its immunoreactivity is possibly not restricted to CD146 associated epitopes.