Osteolytic prostate cancer cells induce the expression of specific cytokines in bone-forming osteoblasts through a Stat3/5-dependent mechanism.
Prostate cancer primarily metastasizes to bone, and the interaction of cancer cells with bone cells results in a local activation of bone formation and/or bone resorption. Since the cellular and molecular mechanisms underlying the development of these tumor-induced osteoblastic or osteolytic lesions are still poorly understood, we have compared the effects of two prostate cancer cell lines, osteoblastic MDA-PCa-2b cells and osteolytic PC-3 cells, on bone-forming osteoblasts. Using Affymetrix Gene Chip hybridization followed by qRT-PCR confirmation we were able to identify specific genes, including Smpd3 and Dmp1, whose expression is significantly reduced upon treatment with PC-3-conditioned medium. Moreover, we observed that PC-3-conditioned medium led to a marked induction of several cytokine genes, including Cxcl5, Cxcl12 and Tnfsf11, the latter one encoding for the osteoclast differentiation factor Rankl. Likewise, when we analyzed the effects of MDA-PCa-2b- and PC-3-conditioned medium on signal transduction in osteoblasts we did not only observe opposite effects on the canonical Wnt signalling pathway, but also a specific induction of Erk and Stat phosphorylation by PC-3-conditioned medium. Most importantly, the induction of Cxcl5, Cxcl12 and Tnfsf11 in osteoblasts by PC-3-conditioned medium was abrogated by the Stat3/5 inhibitor piceatannol, whereas the selective blockade of Stat1 and Erk activation had no effect. Together with the finding, that activated Stat3 in osteoblasts was detectable in bone biopsies from patients with osteolytic metastases, our data suggest that the Stat3/5-dependent activation of cytokine expression in osteoblasts may have a significant impact on cancer cell migration and proliferation, but also on osteoclast activation.
Schulze
Jochen
J
Center of Biomechanics and Skeletal Biology, Department of Trauma, Hand, and Reconstructive Surgery, University Medical Center Hamburg Eppendorf, Hamburg 20246, Germany.
Albers
Joachim
J
Baranowsky
Anke
A
Keller
Johannes
J
Spiro
Alexander
A
Streichert
Thomas
T
Zustin
Jozef
J
Amling
Michael
M
Schinke
Thorsten
T
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects; D010014:Osteolysis / Q000150:complications / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000150:complications / Q000235:genetics / Q000473:pathology*; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D051153:Wnt Proteins / Q000378:metabolism
D018925:Chemokines; D017077:Culture Media, Conditioned; D016207:Cytokines; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D051153:Wnt Proteins