Role of DKK1 in growth and migration of prostate cancer cells

Androgen deprivation therapy is the choice treatment of metastatic prostatic tumors. Unfortunately, very often, resistance occurs and chemotherapy is needed. Results are however disappointing with frequent side effects. Therefore, new therapeutic approaches for metastatic and advanced prostate cancer are necessary. DKK1, an inhibitor of the Wnt signaling pathway, is increased in different types of cancer. In prostate cancer patients with bone metastases, an increase of DKK1 is observed both in the serum and in the prostate tissue, suggesting that DKK1 might be considered as a new molecular target in the metastatic prostate cancer therapy. The aim of this study was to evaluate the role of DKK1 in growth and migration of prostate cancer cell lines (PC3 and DU145), expressing high levels of DKK1. To this end, we carried out DKK1 gene silencing and knockout in PC3 and DU145 cells. Silencing was obtained by specific siRNA to DKK1; permanent knockdown was performed using a CRISPR/CAS9 system. Real-Time PCR, Western Blotting analysis, and secretion levels by ELISA confirmed DKK1 silencing and knockout, respectively. The effects of silencing (PC3-siRNA and DU145-siRNA) and knockdown (PC3-KO and DU145-KO) were evaluated in terms of cell growth by colorimetric WST-1 test and cell migration by transwell migration assay. A significant reduction of mRNA, protein levels and secretion of DKK1 was observed in both cell lines where DKK1 was silenced or knocked-down. Functionally, DKK1 inhibition resulted in a reduction of cell growth and migration. In conclusion, our data support a key role of DKK1 in the growth and migration of prostate cancer cells. Based on our study, DKK1 may represent a specific target for a new therapy intended to specifically block its function in metastatic and advanced prostate cancer.