The TLK1-Nek1 axis promotes prostate cancer progression.

We recently uncovered the critical TLK1>NEK1>ATR > Chk1 axis in mediating the DDR and cell cycle checkpoint while transiting from Androgen Sensitive to Insensitive growth for LNCaP and TRAMP-C2 cells. However, we did not know the generality of this pathway in PCa progression since there are few cell lines where the transition has been studied. Furthermore, the identification of Nek1, and more importantly the TLK-mediated phosphorylation of T141, has never been studied in PCa biopsies. We now report the first study of a PCa TMA of p-Nek1-T141 and correlation to the Gleason score. In addition we found that TRAMP mice treated with the TLK inhibitor, thioridazine (THD), following castration did not recover cancerous growth of their prostates. Moreover, we recapitulated the process of translational increase in TLK1B expression in a naïve PDX model that was established from an AR + adenocarcinoma. Therefore, we believe that this TLK1-Nek1 mediated DDR axis is likely to be a common adaptive response during the transition of PCa cells toward androgen-insensitive growth, and hence CRPC progression, which has the potential to be targeted with THD and other TLK or Nek1 inhibitors.