In epithelial cells alternative splicing of fibroblast growth factor receptor-2 (FGFR2) transcripts leads to the expression of the FGFR2(IIIb) isoform, whereas in mesenchymal cells the same process results in the synthesis of FGFR2(IIIc), which include exon IIIc. This regulated splicing is disrupted during progression of prostate carcinomas leading to the inappropriate expression of FGFR2 isoforms. To visualize the use of FGFR2 exon IIIc in Dunning AT3 tumors in syngeneic rats we constructed minigene constructs that report on alternative splicing. Imaging these alternative splicing decisions revealed unexpected mesenchymal-epithelial transitions (MET) in these primary tumors. The understanding of this epithelial-mesenchymal plasticity, revealed by differences in splicing, is the overarching goal of this application. To this end we propose to accomplish the following specific aims:
Specific Aim 1. To characterize the connections between FGFR2 splicing and epithelial-mesenchymal plasticity in prostate tumors. We have developed a new bichromatic reporter that can be used to detect both MET and epithelial-mesenchymal transitions (EMT). We have also extended our observations to well characterized human prostate tumor cells in culture. Work accomplished in this aim will test the hypothesis that epithelial plasticity is a general property of aggressive prostate carcinomas in humans.
Specific Aim 2. To characterize the epithelial-mesenchymal plasticity in primary prostate tumors revealed by alterations in splicing. In this aim we will characterize the molecular signatures and behavior of the MET clusters in primary tumors.
Specific aim 3. To characterize the connections between epithelial-mesenchymal plasticity and metastatic behavior. We will investigate the connections between epithelial-mesenchymal plasticity and metastatic behavior. Finally, we will isolate circulating prostate tumor cells from both the AT3 rat tumors and patients, and we will determine their FGFR2 splicing status and their epithelial state. Work accomplished in aim two and in this aim will test the hypothesis that epithelial-mesenchymal plasticity leads to increased tumor fitness. The significance of this work is twofold: First we will unravel basic information about gene expression programs controlled by alternative splicing during prostate tumor progression. Second, the potential significance to human health is underscored by the magnitude of prostate cancer as a health problem. Identifying the tumors/cells that will progress to metastatic disease is a challenge and a priority. The work proposed here should identify useful markers and perhaps even therapeutic targets.
The potential significance of our application to human health is underscored by the magnitude of prostate cancer as a health problem, which The American Cancer Society (ACS) predicts will afflict ~200,000 men and will kill >25,000 in the US alone. In addition, prostate cancer presents the clinician and the patient with unique problems in terms of choosing among therapeutic options and predicting eventual outcomes (see New York Times 26 February article A Review of Prostate Cancer Leaves Men in a Muddle). The work proposed here should identify useful markers of tumor behavior and perhaps even targets for novel therapies.
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|Li, Jing; Gregory, Simon G; Garcia-Blanco, Mariano A et al. (2015) Using circulating tumor cells to inform on prostate cancer biology and clinical utility. Crit Rev Clin Lab Sci 52:191-210|
|Bitting, Rhonda L; Schaeffer, Daneen; Somarelli, Jason A et al. (2014) The role of epithelial plasticity in prostate cancer dissemination and treatment resistance. Cancer Metastasis Rev 33:441-68|
|Schaeffer, Daneen; Somarelli, Jason A; Hanna, Gabi et al. (2014) Cellular migration and invasion uncoupled: increased migration is not an inexorable consequence of epithelial-to-mesenchymal transition. Mol Cell Biol 34:3486-99|
|Ware, Kathryn E; Garcia-Blanco, Mariano A; Armstrong, Andrew J et al. (2014) Biologic and clinical significance of androgen receptor variants in castration resistant prostate cancer. Endocr Relat Cancer 21:T87-T103|
|Clarke, J M; Armstrong, A J (2013) Novel therapies for the treatment of advanced prostate cancer. Curr Treat Options Oncol 14:109-26|
|Somarelli, Jason A; Schaeffer, Daneen; Bosma, Reggie et al. (2013) Fluorescence-based alternative splicing reporters for the study of epithelial plasticity in vivo. RNA 19:116-27|
|Bitting, Rhonda L; Boominathan, Rengasamy; Rao, Chandra et al. (2013) Development of a method to isolate circulating tumor cells using mesenchymal-based capture. Methods 64:129-36|
|Robinson, Timothy J; Forte, Eleonora; Salinas, Raul E et al. (2012) SplicerEX: a tool for the automated detection and classification of mRNA changes from conventional and splice-sensitive microarray expression data. RNA 18:1435-45|
|Armstrong, Andrew J; Marengo, Matthew S; Oltean, Sebastian et al. (2011) Circulating tumor cells from patients with advanced prostate and breast cancer display both epithelial and mesenchymal markers. Mol Cancer Res 9:997-1007|
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