RANKL directly induces bone morphogenetic protein-2 expression in RANK-expressing POS-1 osteosarcoma cells

Abstract

Abstract. The POS-1 murine model of osteolytic osteosarcoma was used to elucidate the molecular and cellular mechanisms involved in the development of primary bone tumors and associated lung metastasis. The POS-1 cell line is derived from an osteosarcoma tumor which develops spontaneously in C3H mice. The POS-1 cell line was characterized in vitro by mineralization capacity and expression of bone markers by semi-quantitative RT-PCR, compared to primary osteoblasts and bone marrow cells. POS-1 cells showed no mineralization capacity and exhibited an undifferentiated phenotype, expressing both osteoblastic and unexpected osteoclastic markers (TRAP, cathepsin K and RANK). Thereby, experiments were performed to determine whether RANK was functional, by studying the biological activity of murine RANKL through the receptor RANK expressed on POS-1 cells. Results revealed a RANKL-induced increase in ERK phosphorylation, as well as BMP-2 induction at the mRNA and protein levels, and a decrease of POS-1 cell proliferation in the presence of 10 ng/ml RANKL. BMP-2 induction is dependent on the ERK 1/2 signal transduction pathway, as its expression is abolished in the presence of UO126, a specific synthetic inhibitor of the ERK 1/2 pathway. Moreover, a 2-fold molar excess of soluble RANK blocks the RANKL-induced BMP-2 expression, demonstrating that the biological effects of RANKL observed in POS-1 cells are mediated by RANK. This is the first report describing a functional RANK expressed on osteosarcoma cells, as shown by its ability to induce signal transduction pathways and biological activity when stimulated by RANKL.

DU145 human prostate cancer cells express functional receptor activator of NFκB: New insights in the prostate cancer bone metastasis process

“…However its expression is not restricted to this cell type, as it was also observed in other tissue including mammary gland [29], lung [20], brain [20], kidney [20] and hypertrophic chondrocytes [15]. Recently, functional RANK expression on tumor cells was reported by our laboratory [21] and others [22,30]. Indeed, we have recently reported the expression of functional RANK in POS-1 mouse osteosarcoma cells [21].…”

“…RANK expressed on osteoclast/osteoclast precursors has been largely described as a key receptor that control osteoclast differentiation, activity and survival [12,14,15,20]. However, we and others have demonstrated the expression of functional RANK at the surface of tumor cells that develop in bone, including a mouse osteosarcoma cell line, POS-1 [21,22]. These recent findings bring new insights in the vicious cycle theory between bone resorbing cells and cancer cells [23].…”

“…Previous studies reported that OPG expression by prostate cancer cells [8] and more recently RANK expression by cancer cells [21,22], these all findings therefore led us to elucidate the molecular mechanisms underlying prostate cancer bone metastases and the therapeutic relevance of RANKL/RANK/OPG triad in these processes, using DU145 and PC3 human prostate cancer cell lines.…”

RANKL-induced migration of MDA-MB-231 human breast cancer cells via Src and MAPK activation

“…Interestingly, recent studies found that functional RANK was expressed in some primary and some secondary bone tumors, including osteosarcoma (5,6), chondrosarcoma (7), breast cancer (8), prostate cancer (9,10), renal cell cancer (11) and malignant melanoma (8). RANKL can promote cancer cell migration and invasion in in vitro experiments, and induce osteoclast chemotaxis (7,10,12).…”

Species-specific cis-Regulatory Elements in the 3′-Untranslated Region Direct Alternative Polyadenylation of Bone Morphogenetic Protein 2 mRNA

“…After reaching 70 -80% confluence, cells were treated for 6 h with 100 ng/ml human sRANKL (PeproTech) to induce Bmp2 expression (35). Mouse F9 embryonal carcinoma cells were maintained and induced to differentiate as described previously (18).…”