Daniel G. Gioeli
- PhD, University of North Carolina
- Associate Professor, Microbiology, Immunology, and Cancer Biology
Signal transduction in cancer cells
The overall goal of my research is to understand the mechanistic underpinnings of how signal transduction pathways cross-talk and contribute to cancer progression. Much of my published work to date has focused on how growth factor and androgen signaling facilitates prostate cancer progression. While these studies make up the core of my current research program, this work has also spawned research in additional, related areas. We are now identifying the signaling pathways that compensate for androgen ablation in prostate cancer as well as looking for combinatorial therapeutic targets in melanoma.
The androgen receptor (AR) is essential for the normal development of the prostate gland as well as for the growth and survival of prostate cancers. Most castration resistant prostate tumors continue to express the AR as well as androgen responsive genes, despite the near absence of circulating androgen in these patients. Additionally, data from experimental models and most recently from the clinic suggest that late-stage prostate cancer is still dependent on the AR. Moreover, it is increasingly clear that the AR is regulated not only by its cognate steroid hormone, but also by interactions with a constellation of co-regulatory and signaling molecules, many of which are elevated as prostate cancer progresses. The ability of the AR to function in the absence of physiologic levels of androgen is clearly a consequence of these and other alternative regulatory events. This led to our guiding hypothesis that AR phosphorylation plays a critical role in regulating AR function. We further hypothesize that one or more of these phosphorylations play a role in prostate cancer, affecting gene expression, cell growth, and/or survival.
Previously, we identified the major serine phosphorylation sites on the AR and observed regulation of AR phosphorylation by multiple agonists; this was the first systematic exploration of regulated changes in AR phosphorylation as a possible mechanism for activation/sensitization of AR-dependent gene expression by cell surface receptors and associated downstream effectors. More recently, we have determined that stress kinase signaling regulates AR S650 phosphorylation and that this phosphorylation is required for optimal nuclear export. Pursuing the regulation and function of the other AR phosphorylation sites in prostate cancer is currently the center of our research. We are currently: 1) examining the effect of AR S81 phosphorylation by CDK9 on AR transcriptional activity, 2) determining the effect of the cell cycle on AR phosphorylation and transcription, and 3) determining the role of AR phosphorylation in gene expression, cell growth and survival in prostate cancer. This work will provide important insights into the function of the AR, a major regulator of prostate cancer progression.
Kinases regulating prostate cancer growth:
Our studies on growth factor signaling and the AR have led us to the hypothesis that therapeutic strategies targeting kinase cascades can overcome the compensatory signaling mechanisms that limit the effectiveness of androgen ablation. Through screening a panel of shRNAs targeting 673 human kinases against prostate cancer cells grown in the presence and absence of hormone, we have identified gene targets that regulate both androgen sensitivity and cell growth. This research now focuses on the detailed evaluation of these kinases and their functions in regulating prostate cancer cell growth and survival, and to determine the role of the identified kinases in regulating androgen-AR signaling. These experiments will facilitate our understanding of the signaling networks important for regulating the response of prostate cancer cells to hormone. Ultimately, the outcome of these studies will be the identification of new kinase targets that, when inhibited or manipulated, can improve the effectiveness of androgen ablation therapy.
Paradigms for the rational development of combinatorial therapies:
The use of combinatorial therapies holds much promise since inhibitors targeting a single signaling molecule that is overexpressed and activated in cancer have shown only modest clinical benefit when used as single agents. Therapeutic strategies targeting multiple pathways simultaneously can hypothetically overcome the inherent compensatory, feedback, and redundant signaling mechanisms that limit the effectiveness of single agent therapy. To systematically address this we have utilized an approach analogous to synthetic lethal screening used in yeast genetics. A library of chemical inhibitors targeting signaling proteins was used to search for combinatorial effects on growth of melanoma cell lines in order to functionally identify compensatory and redundant relationships between different signaling components. We have identified combinations of small molecule inhibitors demonstrating superadditive inhibition of growth. We are now evaluating these new combinatorial therapies are testing the response of xenografts to the drug combinations. We will also identify signaling nodes predictive of drug sensitivity as determined by proteomic analysis and mathematical modeling. Through the combination of both the functional identification of compensatory and redundant signaling through our synthetic lethal screen, and the identification of signaling nodes predictive of drug sensitivity determined by proteomic analysis and mathematical modeling, we can continue to refine both our selection of effective drug combinations and the definition of a subset of phospho-proteins that are predictive of drug sensitivity.
In summary, the goal of my research is to understand how crosstalk among signal transduction pathways contributes to cancer progression and how that information can be used to develop more effective cancer treatments.
- Gioeli D, Mandell J, Petroni G, Frierson H, Weber M. Activation of mitogen-activated protein kinase associated with prostate cancer progression. Cancer research. 1999;59(2): 279-84. PMID: 9927031
- Gioeli D, Ficarro S, Kwiek J, Aaronson D, Hancock M, Catling A, White F, Christian R, Settlage R, Shabanowitz J, Hunt D, Weber M. Androgen receptor phosphorylation. Regulation and identification of the phosphorylation sites. The Journal of biological chemistry. 2002;277(32): 29304-14. PMID: 12015328
- Bakin R, Gioeli D, Sikes R, Bissonette E, Weber M. Constitutive activation of the Ras/mitogen-activated protein kinase signaling pathway promotes androgen hypersensitivity in LNCaP prostate cancer cells. Cancer research. 2003;63(8): 1981-9. PMID: 12702592
- Bakin R, Gioeli D, Bissonette E, Weber M. Attenuation of Ras signaling restores androgen sensitivity to hormone-refractory C4-2 prostate cancer cells. Cancer research. 2003;63(8): 1975-80. PMID: 12702591
- Black B, Vitto M, Gioeli D, Spencer A, Afshar N, Conaway M, Weber M, Paschal B. Transient, ligand-dependent arrest of the androgen receptor in subnuclear foci alters phosphorylation and coactivator interactions. Molecular endocrinology (Baltimore, Md.). 2003;18(4): 834-50. PMID: 14684849
- Gioeli D, Black B, Gordon V, Spencer A, Kesler C, Eblen S, Paschal B, Weber M. Stress kinase signaling regulates androgen receptor phosphorylation, transcription, and localization. Molecular endocrinology (Baltimore, Md.). 2005;20(3): 503-15. PMID: 16282370
- Wu Z, Conaway M, Gioeli D, Weber M, Theodorescu D. Conditional expression of PTEN alters the androgen responsiveness of prostate cancer cells. The Prostate. 2006;66(10): 1114-23. PMID: 16637073
- Kraus S, Gioeli D, Vomastek T, Gordon V, Weber M. Receptor for activated C kinase 1 (RACK1) and Src regulate the tyrosine phosphorylation and function of the androgen receptor. Cancer research. 2006;66(22): 11047-54. PMID: 17108144
- Kesler C, Gioeli D, Conaway M, Weber M, Paschal B. Subcellular localization modulates activation function 1 domain phosphorylation in the androgen receptor. Molecular endocrinology (Baltimore, Md.). 2007;21(9): 2071-84. PMID: 17579212
- Bigler D, Gioeli D, Conaway M, Weber M, Theodorescu D. Rap2 regulates androgen sensitivity in human prostate cancer cells. The Prostate. 2007;67(14): 1590-9. PMID: 17918750
- Fiore G, Edwards J, Payne S, Klinkenberg J, Gioeli D, Demas J, Fraser C. Ruthenium(II) tris(bipyridine)-centered poly(ethylenimine) for gene delivery. Biomacromolecules. 2007;8(9): 2829-35. PMID: 17663530
- Shank L, Kelley J, Gioeli D, Yang C, Spencer A, Allison L, Paschal B. Activation of the DNA-dependent protein kinase stimulates nuclear export of the androgen receptor in vitro. The Journal of biological chemistry. 2008;283(16): 10568-80. PMID: 18270197
- Wu Z, Gioeli D, Conaway M, Weber M, Theodorescu D. Restoration of PTEN expression alters the sensitivity of prostate cancer cells to EGFR inhibitors. The Prostate. 2008;68(9): 935-44. PMID: 18386291 | PMCID: PMC2748221
- Kaikkonen S, JÃ¤Ã¤skelÃ¤inen T, Karvonen U, Rytinki M, Makkonen H, Gioeli D, Paschal B, Palvimo J. SUMO-specific protease 1 (SENP1) reverses the hormone-augmented SUMOylation of androgen receptor and modulates gene responses in prostate cancer cells. Molecular endocrinology (Baltimore, Md.). 2009;23(3): 292-307. PMID: 19116244
- DaSilva J, Gioeli D, Weber M, Parsons S. The neuroendocrine-derived peptide parathyroid hormone-related protein promotes prostate cancer cell growth by stabilizing the androgen receptor. Cancer research. 2009;69(18): 7402-11. PMID: 19706771 | PMCID: PMC2803023
- Ni L, Yang C, Gioeli D, Frierson H, Toft D, Paschal B. FKBP51 promotes assembly of the Hsp90 chaperone complex and regulates androgen receptor signaling in prostate cancer cells. Molecular and cellular biology. 2010;30(5): 1243-53. PMID: 20048054 | PMCID: PMC2820886
- Gordon V, Bhadel S, Wunderlich W, Zhang J, Ficarro S, Mollah S, Shabanowitz J, Hunt D, Xenarios I, Hahn W, Conaway M, Carey M, Gioeli D. CDK9 regulates AR promoter selectivity and cell growth through serine 81 phosphorylation. Molecular endocrinology (Baltimore, Md.). 2010;24(12): 2267-80. PMID: 20980437 | PMCID: PMC2999477
- Tilghman R, Cowan C, Mih J, Koryakina Y, Gioeli D, Slack-Davis J, Blackman B, Tschumperlin D, Parsons J. Matrix rigidity regulates cancer cell growth and cellular phenotype. PloS one. 2010;5(9): e12905. PMID: 20886123 | PMCID: PMC2944843
- Kelley J, Talley A, Spencer A, Gioeli D, Paschal B. Karyopherin alpha7 (KPNA7), a divergent member of the importin alpha family of nuclear import receptors. BMC cell biology. 2010;11 63. PMID: 20701745 | PMCID: PMC2929220
- Gioeli D, Wunderlich W, Sebolt-Leopold J, Bekiranov S, Wulfkuhle J, Petricoin E, Conaway M, Weber M. Compensatory pathways induced by MEK inhibition are effective drug targets for combination therapy against castration-resistant prostate cancer. Molecular cancer therapeutics. 2011;10(9): 1581-90. PMID: 21712477 | PMCID: PMC3315368
- Gioeli D, Paschal B. Post-translational modification of the androgen receptor. Molecular and cellular endocrinology. 2011;352(1): 70-8. PMID: 21820033
- Roller D, Axelrod M, Capaldo B, Jensen K, Mackey A, Weber M, Gioeli D. Synthetic lethal screening with small molecule inhibitors provides a pathway to rational combination therapies for melanoma. Molecular cancer therapeutics. 2012. PMID: 22962324 | PMCID: NIHMS405900
- Whitworth H, Bhadel S, Ivey M, Conaway M, Spencer A, Hernan R, Holemon H, Gioeli D. Identification of kinases regulating prostate cancer cell growth using an RNAi phenotypic screen. PloS one. 2012;7(6): e38950. PMID: 22761715 | PMCID: PMC3384611