Exogenous SPARC Suppresses Proliferation and Migration of Prostate Cancer by Interacting With Integrin β1

• Published in: The Prostate Vol. 73; no. 11; pp. 1159 - 1170
• Main Authors: Shin, Minkyoung, Mizokami, Atsushi, Kim, Jungim, Ofude, Mitsuo, Konaka, Hiroyuki, Kadono, Yoshifumi, Kitagawa, Yasuhide, Miwa, Sotaro, Kumaki, Misako, Keller, Evan T., Namiki, Mikio
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.08.2013
• Subjects: Cell Migration Inhibition - physiology; Cell Proliferation; Cells, Cultured; Coculture Techniques; Humans; Integrin beta1 - metabolism; integrin β1; Male; Osteonectin; Prostate - cytology; Prostate - metabolism; Prostate - pathology; prostate cancer; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Protein Binding - physiology; SPARC; stromal cells; Tumor Cells, Cultured; Tumor Suppressor Proteins - metabolism
• ISSN: 0270-4137; 1097-0045
• DOI: 10.1002/pros.22664

BACKGROUND The matricellular protein secreted protein acidic and rich in cysteine (SPARC) plays an important role on tumor metastasis and progression in several cancers. However, the roles of SPARC in prostate cancer (PCa) remain unclear. METHODS To identify SPARC protein in prostate tissue, immunohistochemical analysis of SPARC was conducted using human prostate tissue microarray. To detect SPARC expression in prostate cancer (LNCaP, DU145, and PC‐3) and stromal cells, RT‐PCR, western blot analysis, and ELISA was conducted. To reveal the function of exogenous SPARC in PCa cells, AKT phosphorylation was confirmed by western blot analysis after coculture with stromal cells. Proliferation and migration of PCa cells were examined by addition of SPARC. The interaction between SPARC and integrin β1 was confirmed by western blot analysis after immunoprecipitation. RESULTS SPARC protein was expressed well in normal tissue compared with PCa tissue. ELISA showed high secreted SPARC protein in normal prostate‐derived stromal cell (PrSC) compared with PCa‐derived stromal cell (PCaSC) and PCa. PCa cells cocultured with PrSC showed reduced AKT phosphorylation more than with PCaSC. PCa cells cocultured with PrSC whose SPARC was knocked‐down restored AKT phosphorylation. Moreover, PCa cells treated with SPARC led to reduced AKT phosphorylation. Immunoprecipitation with SPARC revealed interaction of SPARC and integrin β1 in PCa cells. Inhibited proliferation and migration of PCa cells by SPARC was restored by integrin β1 neutralizing antibody. CONCLUSIONS Reduced SPARC secretion from stromal cells might affect PCa progression mediating through limiting AKT phosphorylation after interaction with integrin β1. Prostate 73: 1159–1170, 2013. © 2013 Wiley Periodicals, Inc.