Beta-tubulin III expression in prostate cancer.

Objective: Beta-tubulin isotype III is a microtubule component associated with resistance to chemotherapy and poor outcome in various cancers. This study aimed to investigate its expression in prostate cancer and its role as a prognostic factor in this setting.

Material And Methods: A tissue microarray was constructed of 289 prostate cancers from radical prostatectomy specimens with a median follow-up of 48.9 months. Slides were immunostained for β-tubulin III. The intensity and extent of immunoreactivity and their product [immunoreactivity product (IRP)] were evaluated.

Results: Tubulin III was expressed in the cytoplasm of prostate cancer cells but not in benign glands. Only 11.6% of cancers were positive for tubulin III. Among low-grade (Gleason score 5-6) and high-grade (Gleason score 7-10) cancers, 6.0% and 16.6% were positive, respectively (p = 0.006). β-Tubulin III expression was more often seen in high-stage disease and more often in metastases (62.5%) than in primary lesions (11.6%) (p < 0.001). The intensity, extent and IRP of tubulin III all predicted biochemical recurrence in univariate Cox analysis (p = 0.02, p = 0.048 and p = 0.012, respectively). IRP was an independent predictor of prognosis when adjusted for serum prostate-specific antigen in a multivariate Cox analysis (p = 0.005), but not when the Gleason score was added to the model (p = 0.17).

Conclusion: β-Tubulin III predicts biochemical recurrence after radical prostatectomy in a subset of patients. Its practical utility is limited by the low number of cases positive for this biomarker.