Metastasis is the primary cause of prostate cancer morbidity and mortality. Our previous studies revealed that Sam pointed domain ETS transcription factor, a.k.a. prostate-derived ETS factor (SPDEF/PDEF), inhibits prostate cancer metastasis. However, the mechanism is still unclear. In this study, using microarray and gene set enrichment analysis, we discovered that PDEF upregulated epithelial/luminal differentiation-related genes while it suppressed stemness and epithelial-to-mesenchymal transition-related genes, especially Twist1. We also observed loss of PDEF and gain of Twist1 expression during prostate cancer progression in the TRAMP mouse model. Moreover, Twist1 knockdown resulted in upregulation of PDEF expression, suggesting a reciprocal regulation between PDEF and Twist1. Mechanistically, our ChIP-seq analysis revealed that PDEF directly regulated cytokeratin 18 (CK18) transcription through the GGAT motif within its putative promoter region. CK18 knockdown resulted in increased expression of Twist1, suggesting that PDEF regulated Twist1 in part via CK18. Our analysis of multiple clinical prostate cancer cohorts revealed an inverse relationship between PDEF expression and tumor grade, tumor metastasis, and poor patient survival. Furthermore, a two-gene signature of low PDEF and high Twist1 can better predict poor survival in prostate cancer patients than either gene alone. Collectively, our findings demonstrate PDEF inhibits prostate tumor progression, in part, by directly regulating transcription of CK18, and that PDEF/Twist1 expression could help distinguish between lethal and indolent prostate cancer.Implications: This study reports the novel findings that PDEF suppresses Twist1 partly via CK18 and that PDEF/Twist1 could help distinguish between lethal and indolent prostate cancer.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/16/9/1430/F1.large.jpg Mol Cancer Res; 16(9); 1430-40. ©2018 AACR.
©2018 American Association for Cancer Research.