The pathways that promote prostate cancer survival downstream of the androgen receptor (AR) remain unknown and that lack of knowledge is a critical barrier to the progress of treating prostate cancer. The goal of this proposal is to determine the mechanisms which promote prostate cancer survival in vivo and use this knowledge to test the feasibility of therapeutically targeting those survival pathways. Cell adhesion to extracellular matrix via integrins is critical for the survival of prostate cells. The mechanism by which integrin ?61 is preferentially expressed in prostate cancer, to the virtual exclusion of other integrins, and the extent to which ?61controls cell survival in prostate tumors are not known. A new prostate cancer survival pathway in which AR directly controls ?61 expression was recently identified and published. This pathway functions independently of the PI3K pathway, such that inhibition of both ?61 and PI3K is required to effectively induce prostate cancer cell death. The objective of this proposal is to delineate the mechanisms by which the AR/?61 pathway drives prostate cancer survival and test the feasibility of using combined inhibition of ?61 and PI3K as a therapeutic approach. The hypothesis is that AR-dependent stimulation of integrin ?61 expression is required for NF?B /Bcl-xL/c-FLIP to promote survival of prostate cancer cells, and simultaneous inhibition of the ?61 and PI3K pathways is required to induce death of PI3K-dependent prostate cancer cells.
In Aim 1, AR-expressing cell lines will be used to decipher the transcriptional and post-transcriptional mechanisms by which AR, Erg/Etv, and laminin-10 control integrin ?61 expression in prostate cancer.
In Aim 2, AR-expressing cells will be used to delineate the specific signaling pathways downstream of AR/?61 that control prostate cancer survival.
In Aim 3, human tissue and cell line xenografts will be used to test a new PI3K inhibitor, PX866, currently in phase I trials in combination with ?61 inhibition to suppress tumor survival and growth, and determine the contribution of integrin ?61 and PI3K to tumor survival in vivo. The proposed studies will significantly improve scientific knowledge in the fields of cell adhesion and survival signaling, b delineating the mechanistic basis behind a novel relationship between a nuclear hormone receptor and integrin ?61. Through these studies a more in-depth understanding of how steroids and integrins cooperate to control cell survival will be gained, which will further our knowledge of how the extracellular matrix impacts tumor cell survival. The prostate cancer field will be advanced by linking the prostate-specific Erg/Etv fusion oncogenes with a new AR/?61-dependent, but PI3K-independent, survival pathway that could be part of a strategy for treating prostate cancer patients. Assessment of this pathway in human patient xenografts will help to determine the feasibility of targeting these pathways in vivo and shift current paradigms by demonstrating the importance and contribution of AR to prostate tumor survival through the extracellular matrix.

Public Health Relevance

Annually, prostate cancer is responsible for 29,000 deaths nationwide. How androgen promotes prostate tumor survival remains unknown, and that lack of knowledge is a critical barrier to progress in being able to treat prostate cancer. We identified a novel androgen-regulated prostate cancer cell survival pathway linking the prostate-specific Erg/Etv fusion oncogenes with integrin ?61-dependent survival, and are determining the feasibility of targeting this pathway as a strategy for treating prostate cancer patients to allevite their suffering.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
4R01CA154835-05
Application #
9024459
Study Section
Tumor Cell Biology Study Section (TCB)
Program Officer
Snyderwine, Elizabeth G
Project Start
2012-05-01
Project End
2017-03-31
Budget Start
2016-04-01
Budget End
2017-03-31
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Van Andel Research Institute
Department
Type
DUNS #
129273160
City
Grand Rapids
State
MI
Country
United States
Zip Code
49503
Frank, Sander B; Schulz, Veronique V; Miranti, Cindy K (2017) A streamlined method for the design and cloning of shRNAs into an optimized Dox-inducible lentiviral vector. BMC Biotechnol 17:24
Zarif, Jelani C; Miranti, Cindy K (2016) The importance of non-nuclear AR signaling in prostate cancer progression and therapeutic resistance. Cell Signal 28:348-356
Tesfay, Lia; Schulz, Veronique V; Frank, Sander B et al. (2016) Receptor tyrosine kinase Met promotes cell survival via kinase-independent maintenance of integrin ?3?1. Mol Biol Cell 27:2493-504
Zarif, Jelani C; Lamb, Laura E; Schulz, Veronique V et al. (2015) Androgen receptor non-nuclear regulation of prostate cancer cell invasion mediated by Src and matriptase. Oncotarget 6:6862-76
Berger, Penny L; Frank, Sander B; Schulz, Veronique V et al. (2014) Transient induction of ING4 by Myc drives prostate epithelial cell differentiation and its disruption drives prostate tumorigenesis. Cancer Res 74:3357-68
Akfirat, Canan; Zhang, Xiaotun; Ventura, Aviva et al. (2013) Tumour cell survival mechanisms in lethal metastatic prostate cancer differ between bone and soft tissue metastases. J Pathol 230:291-7
Klionsky, Daniel J (see original citation for additional authors) (2012) Guidelines for the use and interpretation of assays for monitoring autophagy. Autophagy 8:445-544
Lamb, Laura E; Zarif, Jelani C; Miranti, Cindy K (2011) The androgen receptor induces integrin ?6?1 to promote prostate tumor cell survival via NF-?B and Bcl-xL Independently of PI3K signaling. Cancer Res 71:2739-49