We found that expression and activity of RalA &RalB are induced by hypoxia and androgen deprivation (AD) in vitro in parallel with CD24 expression. We determined that a hypoxia-Inducible factor 1a (HlF1a) response element in the 5'region ofthe CD24 gene underlies this effect. Since H!F1a expression is necessary for metastasis in prostate cancer (PCa) and its translation is regulated by mTOR, we evaluated HlF1a protein expression and discovered that expression of RalA and RalB Is required for maximal HlF1a response in hypoxia and AD. We also found that, like HlF1a, RalA undergoes proline dehydroxylation during hypoxia and this promotes engagement with its effector, phospholipase D (PLD), a regulator of mTOR. Further, we identified the elF3b translation initiation component that binds to mTOR. as a direct RalB binding partner. Hence propose the hypothesis that in PCa. Ral GTPases are oxygen and androgen biosensors and their activity allows metastatic PCa cells to overcome the natural and therapeutic adversity of hypoxia and AD by maintaining mTOR-mediated translation of HlF1a.
Specific Aims will test this hypothesis:
Aim 1 will investigate the role of post-translational Ral modifications on HlF1a expression. We will map proline hydroxylation sites in RalA and determine their role in RalA activity and HlF1a expression. We will also evaluate the role of RalB phosphorylation on HIF1a expression, since we have discovered that RalB is activated by phosphorylation at S198 by PKC, a hypoxia activated kinase.
In Aim 2 we determine the nature of Ral expression on global and HlF1a translation and assembly and activity of cap-dependent translational complexes in hypoxia and AD. We also examine these characteristics in RalB mutants deficient in interaction with elF3b.
Aim 3 will determine the requirement for Ral in PCa using human xenografts and novel transgenic models. Gene expression signatures associated with post-translational modifications of Ral will be evaluated in tumors from patients treated by prostatectomy to determine their ability to predict recurrence. Our project provides a new paradigm by showing Ral GTPases are oxygen and androgen sensors that regulate HlF1a while integrating in the P01 by shared aims with other projects and use of all cores.

Public Health Relevance

Hypoxia and androgen deprivation (AD) initially limit growth of prostate cancer (PCa) in bone but these are inevitably overcome, leading to death. We found Ral and CD24 are the molecular bookends of a novel and therapeutically tractable pathway that allows PCa cells to overcome such restrictions. Finding that higher tumor expression of Ral and CD24 in patients and animal models of human PCa are associated with metastasis and androgen independence supports the clinical relevance of this novel pathway.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Program Projects (P01)
Project #
5P01CA104106-08
Application #
8744370
Study Section
Special Emphasis Panel (ZCA1-RPRB-O (J1))
Project Start
2013-09-01
Project End
2016-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
8
Fiscal Year
2013
Total Cost
$452,277
Indirect Cost
$74,707
Name
University of Virginia
Department
Type
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Kumar, Pankaj; Kuscu, Canan; Dutta, Anindya (2016) Biogenesis and Function of Transfer RNA-Related Fragments (tRFs). Trends Biochem Sci 41:679-89
Agarwal, Neeraj; Dancik, Garrett M; Goodspeed, Andrew et al. (2016) GON4L Drives Cancer Growth through a YY1-Androgen Receptor-CD24 Axis. Cancer Res 76:5175-85
Reon, Brian J; Dutta, Anindya (2016) Biological Processes Discovered by High-Throughput Sequencing. Am J Pathol 186:722-32
Sakurai, Kouhei; Reon, Brian J; Anaya, Jordan et al. (2015) The lncRNA DRAIC/PCAT29 Locus Constitutes a Tumor-Suppressive Nexus. Mol Cancer Res 13:828-38
Mueller, Adam C; Cichewicz, Magdalena A; Dey, Bijan K et al. (2015) MUNC, a long noncoding RNA that facilitates the function of MyoD in skeletal myogenesis. Mol Cell Biol 35:498-513
Borah, Sumit; Xi, Linghe; Zaug, Arthur J et al. (2015) Cancer. TERT promoter mutations and telomerase reactivation in urothelial cancer. Science 347:1006-10
Kumar, Pankaj; Mudunuri, Suresh B; Anaya, Jordan et al. (2015) tRFdb: a database for transfer RNA fragments. Nucleic Acids Res 43:D141-5
Earl, Julie; Rico, Daniel; Carrillo-de-Santa-Pau, Enrique et al. (2015) The UBC-40 Urothelial Bladder Cancer cell line index: a genomic resource for functional studies. BMC Genomics 16:403
Dillon, Laura W; Kumar, Pankaj; Shibata, Yoshiyuki et al. (2015) Production of Extrachromosomal MicroDNAs Is Linked to Mismatch Repair Pathways and Transcriptional Activity. Cell Rep 11:1749-59
Zboray, Lori; Pluciennik, Anna; Curtis, Dana et al. (2015) Preventing the Androgen Receptor N/C Interaction Delays Disease Onset in a Mouse Model of SBMA. Cell Rep 13:2312-23

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