FLRT3 and posterior cortical atrophy: It is possible that circCCDC7-180aa acts as a ligand after its extracellular secretion, and then receptor-ligand complexes formed to regulate the expression of FLRT3. Additionally, we believe that the downstream targets of circCCDC7(15,16,17,18,19) are not just FLRT3. More studies in PCa have revealed the critical role of the tumor microenvironment in the initiation and progression to advanced disease45, in which secreted protein is one of the important tools for communicating between tumor and its microenvironment46.