Project description:Osteoclasts (OCs) are bone-resorbing cells differentiated from macrophage/monocyte precursors in response to M-CSF and RANKL. In vitro models are principally based on primary bone marrow macrophages, but RAW 264.7 cells are frequently used because they are widely available, easy to culture, and more amenable to genetic manipulation than primary cells. Increasing evidence, however, has shown that the vastly different origins of these two cell types may have important effects on cell behavior. In particular, M-CSF is prerequisite for the differentiation of BMMs, by promoting survival and proliferation and priming the cells for RANKL induction. RAW 264.7 cells readily form OCs in the presence of RANKL, but M-CSF is not required. Based on these key differences, we sought to understand their functional implications and how it might affect osteoclast differentiation and related signaling pathways. Using a robust and high-throughput proteomics strategy, we quantified the global protein changes in OCs derived from bone marrow macrophages and RAW 264.7 cells at 1, 3, and 5 days of differentiation. Correlation analysis of the proteomes demonstrated low concordance between the two cell types (R2 ≈ 0.13). Bioinformatics analysis indicate that RANKL-dependent signaling was intact in RAW 264.7 cells, but biological processes known to be dependent on M-CSF were significantly different; including cell cycle control, cytoskeletal organization, and apoptosis. RAW 264.7 cells exhibited constitutive activation of Erk and Akt that was dependent on the activity of Abelson tyrosine kinase, and the timing of Erk and Akt activation was significantly different between BMMs and RAW 264.7 cells. Our findings provide the first evidence for major differences between BMMs and RAW 264.7 cells, indicating that careful consideration is needed when using the RAW 264.7 cell line when studying M-CSF-dependent signaling and functions.
Project description:Osteoclast differentiation is crucial for bone absorption and osteoclast is involved in bone destruction in rheumatoid arthritis. The aim of this study was to investigate the inhibitory effect of MJ2 on osteoclast differentiation and to elucidate its mechanism. Murine macrophage cell line, Raw 264.7 cells and collagen-induced arthritis mouse model were used for in vitro and in vivo study, respectively. MJ2-treated cells significantly inhibited osteoclast differentiation and decreased arthritic score. Surface proteins (SP) extracted from MJ2 also showed inhibitory effect on osteoclast differentiation by upregulating lipocalin 2 (lcn2) expression. Specifically, heat shock protein 60 (hsp60) in SP was revealed as an active component of MJ2. Hsp60 inhibited binding of receptor activator of nuclear factor-κB ligand (RANKL) to receptor activator of nuclear factor κB (RANK). In conclusion, MJ2 inhibited osteoclast formation and differentiation through lcn2 and RANKL-binding property and the effective component of MJ2 might be hsp60 present in surface layer.
Project description:We found that RANKL, expressed by cancer cells or derived from exogenous sources, consistently induced human prostate, breast, kidney, lung and liver cancer cells to colonize or metastasize to bone in an animal model of cancer bone metastasis. RANK-mediated signaling established a premetastatic niche through a forward feedback loop by inducing RANKL and c-Met expression and downstream signaling via upregulation of master regulator transcription factors regulating EMT (Twist1, Slug, Zeb1, Zeb2), stem cells (Sox2, Myc, Oct3/4 and Nanog), neuroendocrine cells (Sox 9, HIF-1α and FoxA2) and osteomimicry (c-Myc/Max, Sox2, Sox9, HIF1α and Runx2). Abrogating RANK or its downstream signaling network, c-Myc/Max or c-Met, abolished PCa skeletal metastasis in mice. We observed that a small number of RANKL-expressing PCa cells can initiate bone and soft tissue metastases by recruiting non-tumorigenic or bystander PCa or host cells from the circulation or at metastatic sites to co-colonize bone. The recruited bystander PCa cells assume the phenotypes of RANKL-expressing PCa cells by expressing increased c-Met, phosphorylated c-Met and RANKL. RANKL expression at a single cell level in primary PCa tissues predicted disease-specific survival, reflecting the significant role of RANKL-RANK signaling in the development of lethal bone metastasis. Global gene expression analysis perturbed by RANKL in LNRANKL compared to LNNeo cells.
Project description:We found that RANKL, expressed by cancer cells or derived from exogenous sources, consistently induced human prostate, breast, kidney, lung and liver cancer cells to colonize or metastasize to bone in an animal model of cancer bone metastasis. RANK-mediated signaling established a premetastatic niche through a forward feedback loop by inducing RANKL and c-Met expression and downstream signaling via upregulation of master regulator transcription factors regulating EMT (Twist1, Slug, Zeb1, Zeb2), stem cells (Sox2, Myc, Oct3/4 and Nanog), neuroendocrine cells (Sox 9, HIF-1α and FoxA2) and osteomimicry (c-Myc/Max, Sox2, Sox9, HIF1α and Runx2). Abrogating RANK or its downstream signaling network, c-Myc/Max or c-Met, abolished PCa skeletal metastasis in mice. We observed that a small number of RANKL-expressing PCa cells can initiate bone and soft tissue metastases by recruiting non-tumorigenic or bystander PCa or host cells from the circulation or at metastatic sites to co-colonize bone. The recruited bystander PCa cells assume the phenotypes of RANKL-expressing PCa cells by expressing increased c-Met, phosphorylated c-Met and RANKL. RANKL expression at a single cell level in primary PCa tissues predicted disease-specific survival, reflecting the significant role of RANKL-RANK signaling in the development of lethal bone metastasis.