NE-AUA 2006 Annual Meeting, September 28 - 30, 2006, The Westin Hotel & Rhode Island Convention Center Providence, Rhode Island
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The Role of MET Receptor Expression in Prostate Cancer Cell Lines
Rohit Garg, MBBS, MPH1, Yan Li, MD, PhD2, Charles Cha, MD1, Alp Sener, MD3, Jonathan Hwang, MD4, Jonathan Walker, MD5, Edward M. Uchio, MD1, Stephen Pautler, MD6.
1Department of Surgery, Yale School of Medicine, New Haven, CT, USA 2Cancer Center, Sun Yat-Sen University, Guangzhon City, China 3London Health Sciences Centre, London, ON, Canada 4Robert Wood Johnson University Hospital, New Brunswick, NJ, USA 5Department of Surgery at the University of Arizona College of Medicine, Tucson, AZ, USA 6St. Joseph's Health Care London, St. Joseph's Hospital, London, ON, Canada.

Background: Several genetic factors have been identified in prostate cancer progression and metastasis. One such factor is MET, a proto-oncogene located on chromosome 7q31, encoding for a 190 kDa transmembrane tyrosine kinase receptor found in prostate epithelial cells that is activated locally by the ligand hepatocyte growth factor (HGF). In vitro evidence suggests that this autocrine loop present between HGF and MET plays a significant role in prostate cancer evolution. In addition, in vivo data suggest that HGF may have angiogenic properties in neoplastic epithelial cells. We hypothesize that inhibition of the MET receptor protein will alter the aggressive phenotype in prostate cancer epithelial cell lines as exhibited in invasion assays and branching morphogenesis.
Methods: Human prostate cancer cell lines, DU145 and PC3, were either transfected with siRNA specifically targeting the MET mRNA sequence or with a scramble siRNA (control) using a cationic lipid transfection agent. A fluorescein labeled siRNA was used to assess transfection efficiency using a fluorescence activated cell sorter (FACS). Cells were harvested at 48hrs post transfection and assayed for mRNA and protein expression using real-time quantitative PCR and Western blot, respectively. The phenotypes of these cells were investigated in triplicate using branching morphogenesis and matrigel invasion assays.
Results: Fluorescein labeled siRNA yielded high transfection efficiencies by FACS. Cell lines transfected with MET specific siRNA showed significant inhibition of MET at both the mRNA and protein level as compared to scramble or non-transfected controls. Cell lines lacking the MET receptor protein displayed a lower % invasion on matrigel invasion assays than controls with an invasion index of 0.77. Similar findings were seen in branching morphogenesis assays.
Conclusions: Inhibition of the MET receptor protein is characterized by loss of invasion and branching in prostate cancer cell lines. In vivo studies, may further reveal that this autocrine loop between HGF and MET may be a consequent target with clinical potential.


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