ABSTRACT
Castration resistant prostate cancer (CRPC) remains an incurable disease stage with ineffective treatments options. Here, the androgen receptor (AR) coactivators CBP/p300, which are histone acetyltransferases, were identified as critical mediators of DNA damage repair (DDR) to potentially enhance therapeutic targeting of CRPC. Key findings demonstrate that CBP/p300 expression increases with disease progression and selects for poor prognosis in metastatic disease. CBP/p300 bromodomain inhibition enhances response to standard of care therapeutics. Functional studies, CBP/p300 cistrome mapping, and transcriptome in CRPC revealed that CBP/p300 regulates DDR. Further mechanistic investigation showed that CBP/p300 attenuation via therapeutic targeting and genomic knockdown decreases homologous recombination (HR) factors in vitro, in vivo, and in human prostate cancer (PCa) tumors ex vivo. Similarly, CBP/p300 expression in human prostate tissue correlates with HR factors. Lastly, targeting CBP/p300 impacts HR-mediate repair and patient outcome. Collectively, these studies identify CBP/p300 as drivers of PCa tumorigenesis and lay the groundwork to optimize therapeutic strategies for advanced PCa via CBP/p300 inhibition, potentially in combination with AR-directed and DDR therapies.
ABSTRACT
Higher levels of aneuploidy, characterized by imbalanced chromosome numbers, are associated with lethal progression in prostate cancer. However, how aneuploidy contributes to prostate cancer aggressiveness remains poorly understood. In this study, we assessed in patients which genes on chromosome 8q, one of the most frequently gained chromosome arms in prostate tumors, were most strongly associated with long-term risk of cancer progression to metastases and death from prostate cancer (lethal disease) in 403 patients and found the strongest candidate was cohesin subunit gene, RAD21, with an odds ratio of 3.7 (95% CI 1.8, 7.6) comparing the highest vs. lowest tertiles of mRNA expression and adjusting for overall aneuploidy burden and Gleason score, both strong prognostic factors in primary prostate cancer. Studying prostate cancer driven by the TMPRSS2-ERG oncogenic fusion, found in about half of all prostate tumors, we found that increased RAD21 alleviated toxic oncogenic stress and DNA damage caused by oncogene expression. Data from both organoids and patients indicate that increased RAD21 thereby enables aggressive tumors to sustain tumor proliferation, and more broadly suggests one path through which tumors benefit from aneuploidy.
Subject(s)
Aneuploidy , Carcinogenesis , Cell Cycle Proteins , DNA-Binding Proteins , Disease Progression , Prostatic Neoplasms , Humans , Male , Prostatic Neoplasms/genetics , Prostatic Neoplasms/pathology , Prostatic Neoplasms/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Carcinogenesis/genetics , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Oncogene Proteins, Fusion/genetics , Oncogene Proteins, Fusion/metabolism , Chromosomes, Human, Pair 8/genetics , Gene Expression Regulation, Neoplastic , DNA DamageABSTRACT
Castration resistant prostate cancer (CRPC) remains an incurable disease stage with ineffective treatments options. Here, the androgen receptor (AR) coactivators CBP/p300, which are histone acetyltransferases, were identified as critical mediators of DNA damage repair (DDR) to potentially enhance therapeutic targeting of CRPC. Key findings demonstrate that CBP/p300 expression increases with disease progression and selects for poor prognosis in metastatic disease. CBP/p300 bromodomain inhibition enhances response to standard of care therapeutics. Functional studies, CBP/p300 cistrome mapping, and transcriptome in CRPC revealed that CBP/p300 regulates DDR. Further mechanistic investigation showed that CBP/p300 attenuation via therapeutic targeting and genomic knockdown decreases homologous recombination (HR) factors in vitro, in vivo, and in human prostate cancer (PCa) tumors ex vivo. Similarly, CBP/p300 expression in human prostate tissue correlates with HR factors. Lastly, targeting CBP/p300 impacts HR-mediate repair and patient outcome. Collectively, these studies identify CBP/p300 as drivers of PCa tumorigenesis and lay the groundwork to optimize therapeutic strategies for advanced PCa via CBP/p300 inhibition, potentially in combination with AR-directed and DDR therapies.