Evaluation of HOXB13 as a molecular marker of recurrent prostate cancer

Many patients with prostate cancer have disease recurrence following surgical removal of tumors and fail to respond to androgen ablation therapy. Despite the existence of a number of clinical/pathological factors, it is not possible to predict which patients will fall into this category. The results of our previous studies demonstrated that the HOXB13 homeodomain protein plays a key role in the development of prostate cancer and the progression of this malignancy. In addition, HOXB13 has been reported to predict estrogen-resistant breast cancer tumors. The purpose of this study was to investigate whether HOXB13 could be used as a molecular marker to predict prostate cancer recurrence. To examine the role of HOXB13 as a molecular marker with clinical/pathological data, the expression of HOXB13 was compared using immunohistochemistry in 57 organ-confined prostate cancer tumors obtained by radical prostatectomy. There was no significant correlation between the expression of HOXB13 and most clinical/pathological parameters, including tumor margin, invasion, pathological stage and risk level. The HOXB13 expression levels correlated with the Gleason score and there was a positive correlation with the pre-operative prostate specific antigen (PSA) levels. Accordingly, the tumor specimens from 4 patients who ultimately had biochemical failure (PSA >0.2 ng/ml), all showed a high expression of HOXB13, while their risk levels were either intermediate or high. This is the first study to report that HOXB13, together with other clinical/pathological factors, can be used as a molecular marker to predict the progression of prostate cancer.