We have identified the serine protease PRSS3/mesotrypsin as a molecule that is prognostic for prostate cancer systemic progression following prostatectomy, and that is upregulated in metastatic prostate cancer tissue. We have also found that silencing of mesotrypsin expression in prostate cancer cells inhibits invasiveness in culture and metastasis in an orthotopic mouse model, while treatment of prostate cancer cells with recombinant mesotrypsin stimulates invasive behavior. Our preliminary data suggest that mesotrypsin promotes prostate cancer progression through cleavage of one or more specific substrates in the extracellular matrix (ECM), leading to upregulation of COX-2 and stimulation of invasive behavior. We hypothesize that mesotrypsin may represent both a potential therapeutic target for metastatic prostate cancer and a useful prognostic tissue biomarker of systemic progression. Here, we propose experiments (1) to further define the biological mechanisms by which mesotrypsin promotes prostate cancer progression, (2) to develop potent and selective mesotrypsin inhibitors that will facilitate mechanistic studies in culture and animal models and offer candidates for mesotrypsin-targeted therapeutics, and (3) to evaluate mesotrypsin as a prognostic tissue biomarker.
In Aim 1, we will identify proteolytic substrates of mesotrypsin in ECM using a proteomic approach, and test their impact on invasion using 3D culture models. We will also determine the mechanisms by which mesotrypsin regulates COX-2 transcription using promoter-reporter assays and RNA interference approaches.
In Aim 2, we will employ structure-guided protein engineering to optimize a polypeptide inhibitor of mesotrypsin, and evaluate the impact of this inhibitor on invasion in culture assays and on tumor growth and metastasis in an orthotopic mouse model.
In Aim 3, we will assess mesotrypsin protein staining as a potential prognostic tissue biomarker in a high-risk radical prostatectomy cohort, using a newly developed selective mesotrypsin antibody. We will also determine whether mesotrypsin expression is associated with metastasis to specific organ sites, using a diverse panel of metastatic tissues. The successful completion of these aims will critically improve our understanding of novel molecular mechanisms that underlie prostate cancer progression.

Public Health Relevance

Prostate cancer is the second leading cause of cancer death in men, and metastasis, the spread of cancer from the primary tumor to other organs, is the main cause of death. We have identified mesotrypsin as an enzyme involved in the spread of prostate cancer. By learning more about the role of mesotrypsin in prostate cancer progression, by creating drugs that target mesotrypsin function, and by developing ways to measure mesotrypsin in prostate cancer tissue, we hope to develop new therapies for treating prostate cancer and new prognostic tests to guide treatment strategies for prostate cancer survivors.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA154387-01A1
Application #
8498656
Study Section
Basic Mechanisms of Cancer Therapeutics Study Section (BMCT)
Program Officer
Snyderwine, Elizabeth G
Project Start
2013-04-01
Project End
2018-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
1
Fiscal Year
2013
Total Cost
$338,344
Indirect Cost
$122,150
Name
Mayo Clinic Jacksonville
Department
Type
DUNS #
153223151
City
Jacksonville
State
FL
Country
United States
Zip Code
32224
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Szabó, András; Radisky, Evette S; Sahin-Tóth, Miklós (2014) Zymogen activation confers thermodynamic stability on a key peptide bond and protects human cationic trypsin from degradation. J Biol Chem 289:4753-61
Mehner, Christine; Miller, Erin; Khauv, Davitte et al. (2014) Tumor cell-derived MMP3 orchestrates Rac1b and tissue alterations that promote pancreatic adenocarcinoma. Mol Cancer Res 12:1430-9