Singh, J. N. | bioRxiv Science

bioRxiv2024

MYBL2 drives prostate cancer plasticity and identifies CDK2 as a therapeutic vulnerability in RB1-loss and neuroendocrine prostate cancer

Phenotypic plasticity is a recognized mechanism driving therapeutic resistance in prostate cancer (PCa) patients. While underlying molecular causations driving phenotypic plasticity have been identified, therapeutic success is yet to be achieved. To identify putative master regulator transcription factors (MR-TF) driving phenotypic plasticity in PCa, this work utilized a multiomic approach using genetically engineered mouse models of prostate cancer combined with patient data to identify MYBL2 as a significantly enriched transcription factor in PCa exhibiting phenotypic plasticity. Genetic inhibition of Mybl2 using independent murine PCa cell lines representing phenotypic plasticity demonstrated Mybl2 loss significantly decreased in vivo growth as well as cell fitness and repressed gene expression signatures involved in pluripotency and stemness. Because MYBL2 is currently not druggable, a MYBL2 gene signature was employed to identify cyclin-dependent kinase-2 (CDK2) as a potential therapeutic target. CDK2 inhibition phenocopied genetic loss of Mybl2 and significantly decreased in vivo tumor growth associated with enrichment of DNA damage. Together, this work demonstrates MYBL2 as an important MR-TF driving phenotypic plasticity in PCa. Further, high MYBL2 activity identifies PCa that would be responsive to CDK2 inhibition. SignificancePCa that escapes therapy targeting the androgen receptor signaling pathways via phenotypic plasticity are currently untreatable. Our study identifies MYBL2 as a MR-TF in phenotypic plastic PCa and implicates CDK2 inhibition as novel therapeutic target for this most lethal subtype of PCa.

cancer biology↗

bioRxiv2022

Loss of tristetraprolin activates NF-κB induced phenotypic plasticity and primes transition to lethal prostate cancer

Phenotypic plasticity is a hallmark of cancer and increasingly realized as a mechanism of resistance in androgen indifferent prostate tumors. It is critical to identify mechanisms and actionable targets driving phenotypic plasticity. Here, we report that loss of tristetraprolin (TTP, gene ZFP36), an RNA binding protein that regulates mRNA stability increases NF-{kappa}B activation and is associated with higher rates of aggressive disease and early recurrence in primary prostate cancer (PCa). We examined the clinical and biological impact of ZFP36 loss combined with PTEN loss, a known driver of PCa. Combined loss of PTEN and ZFP36 expression was associated with increased risk of recurrence in multiple independent primary PCa cohorts, and significantly reduced overall survival and time to progression following castration in genetically engineered mouse models. ZFP36 loss alters the cell state that is driven by PTEN loss, demonstrated by positive enrichment of gene sets including EMT, inflammation, TNF/NF-{kappa}B, IL6-JAK/STAT3. ZFP36 loss also induces enrichment of multiple gene sets involved in cell migration, chemotaxis, and proliferation. Use of the NF-{kappa}B inhibitor dimethylaminoparthenolide induced significant therapeutic responses in tumors with PTEN and ZFP36 co-loss and reversed castration resistance. This work identifies a novel molecular mechanism driving phenotypic plasticity and castration resistance through loss of ZFP36 expression, that can be reversed by inhibition of NF-{kappa}B activity.

cancer biology↗