Because the effects of ERβ in transfected PC-3M cells and the fact that ERβ can inhibit the cells' proliferation and induce apoptosis are already known, the primary objective of this study is to observe the in vivo therapeutic effect of attenuated Salmonella carrying PCDNA3.1-ERβ plasmid in hormone-independent PCa in nude mice and clarify the mechanism by which ERβ induces apoptosis in PCa cells. The gene discussed is ESR2; the disease is posterior cortical atrophy.