The Expression And Function Of Dishevelled-2 In The Metastatic Progression Of Prostate Cancer

Background: Prostate carcinoma ( PCa ) is one of the most common malignances in United States and Europe, which was the second cause for males death. Although the incidence of prostate cancer was low in our country, but in recently years confirmed PCa is getting higher and higher in China today with the aging and the diet habit changing. Androgen deprivation therapy (ADT) is generally employed for the treatment of advanced or metastatic prostate cancer, because the growth and progression of prostate cancer are initially androgen-dependent. However, the prostate cancer eventually progresses from an androgen-dependent to an aggressive androgen-independent stage, when it shows poor response to any anti-cancer therapy. It is not clear the mechanism of AIPC informed.It is lack of effective treatment when the prostate cancer change to AIPC. The patient's prognosis is poor, when radiation and chemotherapy is applied.Dishevelled (Dvl) is a well-conserved signaling protein that is required for Wnt signaling.Three Dvl homologs (Dvl-1,-2,and -3) have been identified in hunman ,all are expressed in both embryonic and adult tissues ,including brain ,heart ,lung ,kidney, skeletal muscle ,and others.Up-regulation and overexpression of Dvl proteins have been reported in many cancers,including those of breast, colon, prostate , mesothelium ,and lung. The human Dvl family of proteins have three potential interaction motifs: an N-terminal DIX domain, a central PDZ domain and a C-terminal DEP domain. The presence of a Wnt ligand at the transmembrane receptor Frizzled activates the cytoplasmic protein Dishevelled, which dephosphorylates axin. This decreases the capacity of axin to form complexes with APC andβ-catenin,which inhibits the activity of GSK-3β. Dvl2 as one member of the human Dvl family located on chromosome 17p13.2 , constitutes more than 80% of the Dvl1-3 pool in human HEK 293 cells.However, the precise function and mechanisms of Dvl2 in the human remain unclear in prostate cancer progression.Objective and Methods: To study the expression in the PCa cell lines or tissues; and investigate the effect and underling mechanism of Dishevelled-2 (Dvl2) on the growth and cellular invasiveness in the progression of prostate cancer. we examined the expression of Dishevelled-2 (Dvl2) in PCa cell lines (LNCaP, LNCaP-AI, PC3, DU-145) and 27 PCa tissues using semi-quantitative RT-PCR or real-time RT-PCR. Immunohistochemically, Dvl2 was examined in 109 PCa tissues (ADPC/AIPC:104/5). Using lipofectamine-mediated RNA interference (RNAi) to reduce the expression of Dvl2 in androgen-dependent PCa cell line, LNCaP. And after down-regulation of Dvl2 gene in LNCaP cells, we studied the behavior of the PCa cells, as growth, motility and invasiveness of LNCaP cells.Results:We found the expression of Dvl2 was over-expressed in the majority (14 of 27; 51.9%) of PCa tissues. Immunohistochemically, Dvl2 was negative or low expression for 10 benign prostate hyperplasia cases examined; for major cancer foci in 104 patients, Dvl2 was weakly positive in 24(23.1%), was positive in 57 (54.8%) ,and interestingly, all of 5 AIPC were strongly positive. Statistically, the expression of Dvl2 was significantly correlated with primary Gleason grade of major cancer foci that was immunohisto- -chemically analyzed (p=0.02) and TMN clinical stage (p=0.015), and with Lymph node invasion(p=0.005).We also found Dvl2 was over-expressed in LNCaP lines than in DU-145 and PC-3 cells. LNCaP cells underwent 48-hrs culture in phenol-red free RPMI-1640 medium containing 10% CS-FBS followed by administration of different concentrations of DHT for 24-hrs, and the other group of LNCaP cells underwent 3-day culture in RPMI-1640 medium containing 10% FBS medium after administration of different concentrations of bicalutamide. DHT administration significantly enhanced Dvl2 mRNA expression, while bicalutamide treatment significantly decreased the expression, both in a dose dependent manner. In contrast, PC-3 cells were treated with the same administrations, there was no significant change in Dvl2 mRNA expression. Furthermore, down-regulation of Dvl2 gene in LNCaP cells significantly reduced cell growth, motility and invasiveness, accompany with downregulation of Wnt-3a and MMPs at protein level.Conclusion:Our results firstly indicate that Dvl2 plays an important role in PCa metastasis through the up-regulation of MMPs via Wnt-3a signaling pathway. Silencing the expression of Dvl2 may represent a novel strategy in the future to reduce metastatic disease burden in PCa patients.