Infiltrating T cells promote prostate cancer metastasis via modulation of FGF11→miRNA-541→androgen receptor (AR)→MMP9 signaling.

Early clinical studies suggested infiltrating T cells might be associated with poor outcomes in prostate cancer (PCa) patients. The detailed mechanisms how T cells contribute to PCa progression, however, remained unclear. Here, we found PCa cells have a better capacity to recruit more CD4(+) T cells than the surrounding normal prostate cells via secreting more chemokines-CXCL9. The consequences of more recruited CD4(+) T cells to PCa might then lead to enhance PCa cell invasion. Mechanism dissection revealed that infiltrating CD4(+) T cells might function through the modulation of FGF11→miRNA-541 signals to suppress PCa androgen receptor (AR) signals. The suppressed AR signals might then alter the MMP9 signals to promote the PCa cell invasion. Importantly, suppressed AR signals via AR-siRNA or anti-androgen Enzalutamide in PCa cells also enhanced the recruitment of T cells and the consequences of this positive feed back regulation could then enhance the PCa cell invasion. Targeting these newly identified signals via FGF11-siRNA, miRNA-541 inhibitor or MMP9 inhibitor all led to partially reverse the enhanced PCa cell invasion. Results from in vivo mouse models also confirmed the in vitro cell lines in co-culture studies. Together, these results concluded that infiltrating CD4(+) T cells could promote PCa metastasis via modulation of FGF11→miRNA-541→AR→MMP9 signaling. Targeting these newly identified signals may provide us a new potential therapeutic approach to better battle PCa metastasis.