Reduced expression of α-tocopherol-associated protein is associated with tumor cell proliferation and the increased risk of prostate cancer recurrence

Aim: To examine the impact and prognostic significance of alpha-tocopherol associated protein (TAP) expression in a series of prostate cancer patients. Methods: Tissues from 87 patients underwent radical prostatectomy were examined for TAP expression by immunohistochemistry. The relationships of the staining results, the clinic pathological characteristics and the recurrence times were analyzed. Results: Compared with the adjacent areas of normal and benign glands, immunoreactivity of TAP was reduced in areas of prostate cancer. A lower TAP-positive cell number per mm(2) of the largest cancer area (defined as TAP-PN) was associated with higher clinical stage (r = -0.248, P = 0.0322). Inverse associations were found among the TAP-PN and positive lymph nodes (r = -0.231, P = 0.0325), preoperative prostate-specific antigen (PSA) levels (r = -0.423, P = 0.0043), tumor size (r = -0.315, P = 0.0210) and elevated tumor cell proliferation, which was indicated by the staining of Ki-67 (r = -0.308, P = 0.0026). TAP-PN was a significant predictor of recurrence univariately (P = 0.0006), as well as multivariately, adjusted for known markers including preoperative PSA, clinical stage, Gleason score, surgical margin, extra-prostatic extension, seminal vesicle invasion and lymph node metastasis (P = 0.0012). Conclusion: Reduced expression of TAP was associated with the cell proliferation status of prostate cancer, adverse pathological parameters and the increased risk of recurrence.