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RANKL acts directly on RANK‐expressing prostate tumor cells and mediates migration and expression of tumor metastasis genes
Author(s) -
Armstrong Allison P.,
Miller Robert E.,
Jones Jon C.,
Zhang Jian,
Keller Evan T.,
Dougall William C.
Publication year - 2007
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/pros.20678
Subject(s) - rankl , stromal cell , prostate cancer , bone metastasis , cancer research , osteoclast , osteolysis , rank ligand , prostate , metastasis , medicine , tumor progression , receptor , cancer , pathology , activator (genetics) , surgery
BACKGROUND Metastases to bone are a frequent complication of human prostate cancer and result in the development of osteoblastic lesions that include an underlying osteoclastic component. Previous studies in rodent models of breast and prostate cancer have established that receptor activator of NF‐κB ligand (RANKL) inhibition decreases bone lesion development and tumor growth in bone. RANK is essential for osteoclast differentiation, activation, and survival via its expression on osteoclasts and their precursors. RANK expression has also been observed in some tumor cell types such as breast and colon, suggesting that RANKL may play a direct role on tumor cells. METHODS Male CB17 severe combined immunodeficient (SCID) mice were injected with PC3 cells intratibially and treated with either PBS or human osteprotegerin (OPG)‐Fc, a RANKL antagonist. The formation of osteolytic lesions was analyzed by X‐ray, and local and systemic levels of RANKL and OPG were analyzed. RANK mRNA and protein expression were assessed on multiple prostate cancer cell lines, and events downstream of RANK activation were studied in PC3 cells in vitro. RESULTS OPG‐Fc treatment of PC3 tumor‐bearing mice decreased lesion formation and tumor burden. Systemic and local levels of RANKL expression were increased in PC3 tumor bearing mice. PC3 cells responded to RANKL by activating multiple signaling pathways which resulted in significant changes in expression of genes involved in osteolysis and migration. RANK activation via RANKL resulted in increased invasion of PC3 cells through a collagen matrix. CONCLUSION These data demonstrate that host stromal RANKL is induced systemically and locally as a result of PC3 prostate tumor growth within the skeleton. RANK is expressed on prostate cancer cells and promotes invasion in a RANKL‐dependent manner. Prostate 68: 92–104, 2008. © 2007 Wiley‐Liss, Inc.