Association of doublecortin-like kinase 1 with tumor aggressiveness and poor biochemical recurrence-free survival in prostate cancer

BACKGROUND: Doublecortin-like kinase 1 (DCLK1) has been proven to be involved in numerous tumors, while its role in prostate cancer (PCa) is still unclear. This study aimed at investigating the expression pattern and prognostic value of DCLK1 in PCa. PATIENTS AND METHODS: Real-time polymerase chain reaction and Western blot were employed to determine DCLK1 mRNA and protein levels in 25 paired fresh samples of PCa and benign prostatic hyperplasia (BPH) as well as in PCa cell lines. Immunohistochemistry (IHC) was also performed in 125 PCa and 65 BPH tissues to assess DCLK1 expression. Then, the association of DCLK1 expression with clinicopathological parameters and biochemical recurrence (BCR) after radical prostatectomy was statistically analyzed. In addition, the role of DCLK1 in PCa cell proliferation, migration, and invasion was evaluated by using MTT and transwell assays. RESULTS: The mRNA and protein levels of DCLK1 were markedly higher in the fresh samples of PCa than that in BPH. Consistently, IHC revealed increased expression of DCLK1 in PCa paraffin-embedded tissues compared with BPH. Moreover, increased DCLK1 expression was significantly associated with postoperative Gleason grading (P=0.012), pathological T stage (P=0.001), seminal vesicle invasion (P=0.026), and lymph node involvement (P=0.017), respectively. The Kaplan–Meier curve analysis demonstrated that high DCLK1 expression was associated with lower postoperative BCR-free survival (bRFS). Furthermore, multivariate Cox analysis showed that postoperative Gleason grading (P=0.018), pathological T stage (P<0.001), seminal vesicle invasion (P=0.012), lymph node involvement (P=0.014), and DCLK1 expression (P=0.014) were independent predictors of BCR. In vitro, the overexpression and knockdown of DCLK1 in PCa cell lines indicated that DCLK1 could promote cell proliferation, migration, and invasion. CONCLUSION: Increased DCLK1 expression is associated with PCa aggressiveness and may independently predict poor bRFS in patients with PCa.