title: The Role of Osteoclasts in Early Dissemination of Prostate Cancer Tumor Cells.
abstract: Prostate cancer (PCa) is one of the most common neoplasms that metastasize to bone. The aim of this study was to determine if osteoclasts play a role in the seeding of disseminated tumor cells to the bone marrow by mobilizing hematopoietic stem cells (HSCs) out of their marrow niche. Human PC-3Luccells were introduced into male SCID mice by intracardiac (i.c.) injection after mice were treated with the antiresorptive agent Zoledronic Acid (bisphosphonate (BP)) and/or AMD3100, which mobilizes HSCs out of the marrow. Short term homing of PC-3 was assessed at 24 hours byQPCR for humanAluand luciferase and HSC number was determined by FACS. Mice also received pre and/or post treatments of BP by intraperiteneal (i.p.) injections, in addition to PC-3lucby intratibial (i.t.) injections. TRAP assays were used to determine the osteoclast (OC) number in both studies. AMD3100 enhanced the release of HSCs from the bone marrow, while BP increased the retention of HSCs. PCa entry into bone was facilitated in AMD3100, BP, and AMD3100+BP treatments. Before PCa injection, the number of TRAP+ OC was increased in mice treated with AMD3100, while treatment with BP resulted in relatively lower TRAP+ OCs. TRAP+ OCs were not detected in the AMD3100 + BP treatment. After PCa injection, however, the number of TRAP+ OCs was dramatically increased, but did not differ significantly amongst the treatment groups. The pre and post BP treatments in the Nude mice decreased the size of PCa lesions in the tibia compared to the control. The results indicate that OC activation is not necessary for PCa metastasis to bone at the earliest stages. These findings are critical in proving that OCs' contribution to metastasis occur during the growth phase of the tumor rather than at the initiation phase.
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Zalucha
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Jung
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: J
authors.initials: J
authors.lastname: Joseph
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Berry
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA. ; Department of Cancer Biology and Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Shiozawa
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Taichman
keywords: Cancer Stem Cells; Disseminated Tumor Cells; Osteoblasts; Osteoclasts; Prostate Cancer