Research

A doxycycline-inducible urokinase receptor (uPAR) upregulates uPAR activities including resistance to anoikis in human prostate cancer cell lines

Mohammad Hasanuzzaman¹ , Robert Kutner² , Siamak Agha-Mohammadi³ , Jakob Reiser² and Inder Sehgal¹

¹  LSU Department of Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, LA 70803, USA

²  LSU Health Sciences Center New Orleans, Gene Therapy Program, Department of Medicine, New Orleans, LA 70112, USA

³  University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA

author email corresponding author email

Molecular Cancer 2007, 6:34doi:10.1186/1476-4598-6-34

Published:	17 May 2007

Abstract

Background

The urokinase receptor (uPAR) mediates a diverse array of cellular processes including several events involved in prostate cancer metastasis. Many of these activities are initiated or enhanced by uPAR binding to its proteolytic ligand, urokinase (uPA). Our objective in this study was to generate and test an inducible lentiviral system capable of expressing uPAR and DsRed fluorescent protein in human prostate cancer cell lines.

Results

A DsRed-uPAR fusion construct was inserted into a lentiviral vector. Transduction of human prostate cancer cell lines with this virus and with a virus containing a reverse-tetracycline transactivator (rt-TA) resulted in a stable transgene which induced both uPAR and DsRed proteins in a dose-responsive fashion upon stimulation with doxycycline. Immunoblots and immunofluorescence studies indicated no detectable uPAR expression in non-induced prostate cancer cell lines. Cells with induced-uPAR demonstrated increased cellular adhesion to the matrix substrate vitronectin and increased net cell proliferation compared to uninduced cells. Finally, induced uPAR-expressing prostate cancer cells were resistant to anoikis over an extended time period when grown in suspension.

Conclusion

This doxycycline-inducible lentivirus system produces titerable levels of biologically active uPAR in vitro. This tool can be used to dissect cellular events following induction of uPAR in prostate cancer cells.