Prostate-specific antigen modulates genes involved in bone remodeling and induces osteoblast differentiation of human osteosarcoma cell line SaOS-2.
OBJECTIVE
The high prevalence of osteoblastic bone metastases in prostate cancer involves the production of osteoblast-stimulating factors by prostate cancer cells. Prostate-specific antigen (PSA) is a serine protease uniquely produced by prostate cancer cells and is an important serologic marker for prostate cancer. In this study, we examined the role of PSA in the induction of osteoblast differentiation.


METHODS
Human cDNA containing a coding region for PSA was transfected into human osteosarcoma SaOS-2 cells. SaOS-2 cells were also treated with exogenously added PSA. We evaluated changes in global gene expression using cDNA arrays and Northern blot analysis resulting from expression of PSA in human osteosarcoma SaOS-2 cells.


RESULTS
SaOS-2 cells expressing PSA had markedly up-regulated expression of genes associated with osteoblast differentiation including runx-2 and osteocalcin compared with the controls. Consistent with these results, the stable clones expressing PSA showed increased mineralization and increased activity of alkaline phosphatase in vitro compared with controls, suggesting that these cells undergo osteoblast differentiation. We also found that osteoprotegerin expression was down-regulated and that the receptor activator of NF-kappaB ligand expression was up-regulated in cells expressing PSA compared with controls.


CONCLUSIONS
Modulation of the expression of osteogenic genes and alteration of the balance between osteoprotegerin-receptor activator of NF-kappaB ligand by PSA suggests that PSA produced by metastatic prostate cancer cells may participate in bone remodeling in favor of the development of osteoblastic metastases in the heterogeneous mixture of osteolytic and osteoblastic lesions. These findings provide a molecular basis for understanding the high prevalence of osteoblastic bone metastases in prostate cancer.
Nadiminty
Nagalakshmi
N
Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
Lou
Wei
W
Lee
Soo Ok
SO
Mehraein-Ghomi
Farideh
F
Kirk
Jason S
JS
Conroy
Jeffrey M
JM
Zhang
Haitao
H
Gao
Allen C
AC
D000469:Alkaline Phosphatase / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015152:Blotting, Northern; D001859:Bone Neoplasms / Q000378:metabolism* / Q000473:pathology; D016723:Bone Remodeling; D002113:Calcification, Physiologic; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D053244:Osteoprotegerin; D012516:Osteosarcoma / Q000378:metabolism* / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; D000469:Alkaline Phosphatase; D017430:Prostate-Specific Antigen