A Novel Role for DNA-PK in Metabolism by Regulating Glycolysis in Castration Resistant Prostate Cancer

Published first January 24, 2022.Purpose: DNA-dependent protein kinase catalytic subunit (DNA-PKcs, herein referred as DNA-PK) is a multifunctional kinase of high cancer relevance. DNA-PK is deregulated in multiple tumor types, including prostate cancer, and is associated with poor outcomes. DNA-PK was previously nominated as a therapeutic target and DNA-PK inhibitors are currently undergoing clinical investigation. Although DNA-PK is well studied in DNA repair and transcriptional regulation, much remains to be understood about the way by which DNA-PK drives aggressive disease phenotypes. Experimental Design: Here, unbiased proteomic and metabolomic approaches in clinically relevant tumor models uncovered a novel role of DNA-PK in metabolic regulation of cancer progression. DNA-PK regulation of metabolism was interrogated using pharmacologic and genetic perturbation using in vitro cell models, in vivo xenografts, and ex vivo in patient-derived explants (PDE). Results: Key findings reveal: (i) the first-in-field DNA-PK protein interactome; (ii) numerous DNA-PK novel partners involved in glycolysis; (iii) DNA-PK interacts with, phosphorylates (in vitro), and increases the enzymatic activity of glycolytic enzymes ALDOA and PKM2; (iv) DNA-PK drives synthesis of glucosederived pyruvate and lactate; (v) DNA-PK regulates glycolysis in vitro, in vivo, and ex vivo; and (vi) combination of DNA-PK inhibitor with glycolytic inhibitor 2-deoxyglucose leads to additive anti-proliferative effects in aggressive disease. Conclusions: Findings herein unveil novel DNA-PK partners, substrates, and function in prostate cancer. DNA-PK impacts glycolysis through direct interaction with glycolytic enzymes and modulation of enzymatic activity. These events support energy production that may contribute to generation and/or maintenance of DNA-PK–mediated aggressive disease phenotypes.Emanuela Dylgjeri, Vishal Kothari, Ayesha A. Shafi, Galina Semenova, Peter T. Gallagher, Yi F. Guan, Angel Pang, Jonathan F. Goodwin, Swati Irani, Jennifer J. McCann, Amy C. Mandigo, Saswati Chand, Christopher M. McNair, Irina Vasilevskaya, MatthewJ. Schiewer, Costas D. Lallas, Peter A. McCue, Leonard G. Gomella, Erin L. Seifert, Jason S. Carroll, Lisa M. Butler, Jeff Holst, William K. Kelly, and Karen E. Knudse

Targeting cell cycle and hormone receptor pathways in cancer

The cyclin/cyclin-dependent kinase (CDK)/retinoblastoma (RB)-axis is a critical modulator of cell cycle entry and is aberrant in many human cancers. New nodes of therapeutic intervention are needed that can delay or combat the onset of malignancies. The antitumor properties and mechanistic functions of PD-0332991 (PD; a potent and selective CDK4/6 inhibitor) were investigated using human prostate cancer (PCa) models and primary tumors. PD significantly impaired the capacity of PCa cells to proliferate by promoting a robust G1-arrest. Accordingly, key regulators of the G1-S cell cycle transition were modulated including G1 cyclins D, E and A. Subsequent investigation demonstrated the ability of PD to function in the presence of existing hormone-based regimens and to cooperate with ionizing radiation to further suppress cellular growth. Importantly, it was determined that PD is a critical mediator of PD action. The anti-proliferative impact of CDK4/6 inhibition was revealed through reduced proliferation and delayed growth using PCa cell xenografts. Finally, first-in-field effects of PD on proliferation were observed in primary human prostatectomy tumor tissue explants. This study shows that selective CDK4/6 inhibition, using PD either as a single-agent or in combination, hinders key proliferative pathways necessary for disease progression and that RB status is a critical prognostic determinant for therapeutic efficacy. Combined, these pre-clinical findings identify selective targeting of CDK4/6 as a bona fide therapeutic target in both early stage and advanced PCa and underscore the benefit of personalized medicine to enhance treatment response.C E S Comstock, M A Augello, J F Goodwin, R de Leeuw, M J Schiewer, W F Ostrander Jr, R A Burkhart, A K McClendon, P A McCue, E J Trabulsi, C D Lallas, L G Gomella, M M Centenera, J R Brody, L M Butler, W D Tilley and K E Knudse

Status of Biodiversity in the Baltic Sea

The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system's diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity

Drug discovery in advanced prostate cancer: translating biology into therapy.

Castration-resistant prostate cancer (CRPC) is associated with a poor prognosis and poses considerable therapeutic challenges. Recent genetic and technological advances have provided insights into prostate cancer biology and have enabled the identification of novel drug targets and potent molecularly targeted therapeutics for this disease. In this article, we review recent advances in prostate cancer target identification for drug discovery and discuss their promise and associated challenges. We review the evolving therapeutic landscape of CRPC and discuss issues associated with precision medicine as well as challenges encountered with immunotherapy for this disease. Finally, we envision the future management of CRPC, highlighting the use of circulating biomarkers and modern clinical trial designs

Identification of ASF/SF2 as a critical, allele-specific effector of the cyclin D1b oncogene

The cyclin D1b oncogene arises from alternative splicing of the CCND1 transcript, and harbors markedly enhanced oncogenic functions not shared by full-length cyclin D1 (cyclin D1a). Recent studies showed that cyclin D1b is selectively induced in a subset of tissues as a function of tumorigenesis; however, the underlying mechanism(s) that control tumor-specific cyclin D1b induction remain unsolved. Here, we identify the RNA-binding protein ASF/SF2 as a critical, allele-specific, disease-relevant effector of cyclin D1b production. Initially, it was observed that SF2 associates with cyclin D1b mRNA (transcript-b) in minigene analyses and with endogenous transcript in prostate cancer (PCa) cells. SF2 association was altered by the CCND1 G/A870 polymorphism, which resides in the splice donor site controlling transcript-b production. This finding was significant, as the A870 allele promotes cyclin D1b in benign prostate tissue, but in primary PCa, cyclin D1b production is independent of A870 status. Data herein provide a basis for this disparity, as tumor-associated induction of SF2 predominantly results in binding to and accumulation of G870-derived transcript-b. Finally, the relevance of SF2 function was established, as SF2 strongly correlated with cyclin D1b (but not cyclin D1a) in human PCa. Together, these studies identify a novel mechanism by which cyclin D1b is induced in cancer, and reveal significant evidence of a factor that cooperates with a risk-associated polymorphism to alter cyclin D1 isoform production. Identification of SF2 as a disease-relevant effector of cyclin D1b provides a basis for future studies designed to suppress the oncogenic alternative splicing event

Cell cycle-coupled expansion of AR activity promotes cancer progression.

The androgen receptor (AR) is required for prostate cancer (PCa) survival and progression, and ablation of AR activity is the first line of therapeutic intervention for disseminated disease. While initially effective, recurrent tumors ultimately arise for which there is no durable cure. Despite the dependence of PCa on AR activity throughout the course of disease, delineation of the AR-dependent transcriptional network that governs disease progression remains elusive, and the function of AR in mitotically active cells is not well understood. Analyzing AR activity as a function of cell cycle revealed an unexpected and highly expanded repertoire of AR-regulated gene networks in actively cycling cells. New AR functions segregated into two major clusters: those that are specific to cycling cells and retained throughout the mitotic cell cycle ('Cell Cycle Common'), versus those that were specifically enriched in a subset of cell cycle phases ('Phase Restricted'). Further analyses identified previously unrecognized AR functions in major pathways associated with clinical PCa progression. Illustrating the impact of these unmasked AR-driven pathways, dihydroceramide desaturase 1 was identified as an AR-regulated gene in mitotically active cells that promoted pro-metastatic phenotypes, and in advanced PCa proved to be highly associated with development of metastases, recurrence after therapeutic intervention and reduced overall survival. Taken together, these findings delineate AR function in mitotically active tumor cells, thus providing critical insight into the molecular basis by which AR promotes development of lethal PCa and nominate new avenues for therapeutic intervention