Evidence for context-dependent functions of KDM5B in prostate development and prostate cancer

Prostate cancer (PCa) is one of the leading causes of cancer-related deaths worldwide. Prostate tumorigenesis and PCa progression involve numerous genetic as well as epigenetic perturbations. Histone modification represents a fundamental epigenetic mechanism that regulates diverse cellular processes, and H3K4 methylation, one such histone modification associated with active transcription, can be reversed by dedicated histone demethylase KDM5B (JARID1B). Abnormal expression and functions of KDM5B have been implicated in several cancer types including PCa. Consistently, our bioinformatics analysis reveals that the KDM5B mRNA levels are upregulated in PCa compared to benign prostate tissues, and correlate with increased tumor grade and poor patient survival, supporting an oncogenic function of KDM5B in PCa. Surprisingly, however, when we generated prostate-specific conditional Kdm5b knockout mice using probasin (Pb) promoter-driven Cre: loxP system, we observed that Kdm5b deletion did not affect normal prostate development but instead induced mild hyperplasia. These results suggest that KDM5B may possess context-dependent roles in normal prostate development vs. PCa development and progression.