Proteomic Profiling of Androgen-independent Prostate Cancer Cell Lines Reveals a Role for Protein S during the Development of High Grade and Castration-resistant Prostate Cancer

Punit Saraon,Natasha Musrap,Daniela Cretu,George S Karagiannis,Ihor Batruch,Chris Smith,Andrei P Drabovich,Dominique Trudel,Theodorus Van Der Kwast,Colm Morrissey,Keith A Jarvi,Eleftherios P Diamandis

doi:10.1074/jbc.m112.384438

Abstract

Androgen deprivation constitutes the principal therapy for advanced and metastatic prostate cancers. However, this therapeutic intervention usually results in the transition to a more aggressive androgen-independent prostate cancer. The elucidation of molecular alterations during the progression to androgen independence is an integral step toward discovering more effective targeted therapies. With respect to identifying crucial mediators of this transition, we compared the proteomes of androgen-independent (PC3, DU145, PPC1, LNCaP-SF, and 22Rv1) and androgen-dependent (LNCaP and VCaP) and/or normal prostate epithelial (RWPE) cell lines using mass spectrometry. We identified more than 100 proteins that were differentially secreted in the androgen-independent cell lines. Of these, Protein S (PROS1) was elevated in the secretomes of all of the androgen-independent prostate cancer cell lines, with no detectable secretion in normal and androgen-dependent cell lines. Using quantitative PCR, we observed significantly higher (p < 0.05) tissue expression levels of PROS1 in prostate cancer samples, further indicating its importance in prostate cancer progression. Similarly, immunohistochemistry analysis revealed elevation of PROS1 in high grade prostate cancer (Gleason grade ≥ 8), and further elevation in castration-resistant metastatic prostate cancer lesions. We also observed its significant (p < 0.05) elevation in high grade prostate cancer seminal plasma samples. Taken together, these results show that PROS1 is elevated in high grade and castration-resistant prostate cancer and could serve as a potential biomarker of aggressive disease.

Highlights

The mechanisms that cause castration-resistant prostate cancer remain unknown
Cell culture media specified by the ATCC for each of the cell lines were used as follows: Dulbecco’s modified Eagle’s medium (DMEM) (ATCC) with 10% fetal bovine serum (Thermo Scientific) was used for PC3, DU145, and VCaP; Roswell Park Memorial Institute (RPMI) (ATCC) with 10% FBS was used for 22RV1, PPC-1, and LNCaP cells
Proteomic Profiling of Prostate Cancer Cell Line Conditioned Media—To identify modulators of androgen-independent prostate cancer that could serve as potential biomarkers of aggressive disease, we performed an in depth proteomic analysis of the conditioned media of five androgen-independent prostate cancer cell lines (DU145, PC3, LNCaP-SF, PPC-1, and 22Rv1), two androgen-dependent cell lines (LNCaP and VCaP), and one “near normal” prostate epithelial cell line (RWPE)

Summary

Introduction

Results: Using high throughput proteomics and subsequent clinical validation, we identified Protein S as being elevated in high grade/advanced prostate cancer. Androgen deprivation constitutes the principal therapy for advanced and metastatic prostate cancers. This therapeutic intervention usually results in the transition to a more aggressive androgen-independent prostate cancer. With respect to identifying crucial mediators of this transition, we compared the proteomes of androgen-independent (PC3, DU145, PPC1, LNCaP-SF, and 22Rv1) and androgen-dependent (LNCaP and VCaP) and/or normal prostate epithelial (RWPE) cell lines using mass spectrometry. Protein S (PROS1) was elevated in the secretomes of all of the androgen-independent prostate cancer cell lines, with no detectable secretion in normal and androgen-dependent cell lines.

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