In the present study, after examining the inhibiting effect of HDGF knockdown on migration and invasion of Pca cells, we then investigated the molecular events associated with EMT and the expression level of MMPs, mainly including MMP2 and MMP9 after stable HDGF knockdown in PCa cells DU145, PC3 and LNCaP. The gene discussed is MMP9; the disease is posterior cortical atrophy.