The attenuation of miR-449a, significantly suppressed in ERG-positive PCa tissues, facilitates the invasive phenotype by directly upregulating SIRT1 expression, thereby creating a feedback regulatory loop between ERG, miR-449a, and SIRT1 [154], and SIRT1 suppression results in decreased ERG expression and is linked to the modulation of p53 acetylation. The gene discussed is SIRT1; the disease is posterior cortical atrophy.