title: Osteoprotegerin in prostate cancer bone metastasis.
abstract: Osteoprotegerin (OPG), a critical regulator of osteoclastogenesis, is expressed by prostate cancer cells, and OPG levels are increased in patients with prostate cancer bone metastases. The objective of this study was to investigate the effects of OPG overexpression on prostate cancer cells and prostate cancer/bone cell interactions in vitro and in vivo. OPG-transfected C4-2 cells expressed 8.0 ng OPG per mL per 10(6) cells, whereas no OPG was detected in the media of C4-2 cells transfected with a control plasmid. OPG overexpressed by C4-2 cells protected these cells from tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis and decreased osteoclast formation. Subcutaneous OPG-C4-2 and pcDNA-C4-2 tumors exhibited similar growth and take-rate characteristics. However, when grown in bone, tumor volume was decreased in OPG-C4-2 versus pcDNA-C4-2 (P=0.0017). OPG expressed by C4-2 cells caused increases in bone mineral density (P=0.0074) and percentage of trabecular bone volume (P=0.007), and decreases in numbers of osteoblasts and osteoclasts when compared with intratibial pcDNA-C4-2 tumors (P=0.003 and P=0.019, respectively). In summary, our data show that increased expression of OPG in C4-2 cells does not directly affect proliferation of prostate cancer cells but indirectly decreases growth of C4-2 tumors in the bone environment. Our data also show that OPG expressed by C4-2 cells inhibits bone lysis associated with C4-2 bone metastasis, which results in net increases in bone volume. We therefore hypothesize that OPG expressed in prostate cancer patient bone metastases may be at least partially responsible for the osteoblastic character of most prostate cancer bone lesions.
authors.affiliation: Department of Urology, University of Washington, Seattle, Washington 98195, USA. ecorey@u.washington.edu
authors.forename: Eva
authors.initials: E
authors.lastname: Corey
authors.forename: Lisha G
authors.initials: LG
authors.lastname: Brown
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kiefer
authors.forename: Janna E
authors.initials: JE
authors.lastname: Quinn
authors.forename: Tiffany E M
authors.initials: TE
authors.lastname: Pitts
authors.forename: Julie M
authors.initials: JM
authors.lastname: Blair
authors.forename: Robert L
authors.initials: RL
authors.lastname: Vessella
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D001859:Bone Neoplasms / Q000378:metabolism* / Q000556:secondary; D017077:Culture Media, Conditioned; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D016513:Mice, SCID; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology; D010014:Osteolysis / Q000378:metabolism / Q000473:pathology; D053244:Osteoprotegerin; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor; D015996:Survival Rate; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D051017:Apoptosis Regulatory Proteins; D017077:Culture Media, Conditioned; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C506030:TNFRSF11B protein, human; C505653:TNFSF10 protein, human; C506031:Tnfrsf11b protein, mouse; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha