TIP5 primes prostate luminal cells for the oncogenic transformation mediated by PTEN-loss

Prostate cancer (PCa) is the second leading cause of cancer death in men. Its clinical and molecular heterogeneity and the lack of in vitro models outline the complexity of PCa in the clinical and research settings. We established an in vitro mouse PCa model based on organoid technology that takes into account the cell of origin and the order of events. Primary PCa with deletion of the tumor suppressor gene PTEN (PTEN-del) can be modeled through Pten-downregulation in mouse organoids. We used this system to elucidate the contribution of TIP5 in PCa initiation, a chromatin regulator that is implicated in aggressive PCa. High TIP5 expression correlates with primary PTEN-del PCa and this combination strongly associates with reduced PSA recurrence-free survival. TIP5 is critical for the initiation of PCa of luminal origin mediated by Pten loss whereas it is dispensable once Pten-loss mediated transformation is established. Cross-species analyses revealed a PTEN gene signature that identified a group of aggressive primary PCa characterized by PTEN-deletion, high-TIP5 expression, and a TIP5-regulated gene expression profile. The results highlight the modelling of PCa with organoids as a powerful tool to elucidate the role of genetic alterations found in recent studies in their time order and cell of origin, thereby providing further optimization for tumour stratification to improve the clinical management of PCa. Transcriptomic analysis of Tip5 depeltion in basal and luminal mouse prostate epithelial cells. Transcriptomic analysis of gene expression in mouse prostate organoids upon Pten downregulation and Tip5 depletion in different cellular context and time order.