osteoprotegerin and Cell-Transformation--Neoplastic

BRCA1 mutation carriers face a high lifetime risk of breast cancer, estimated at 60 % compared to 10 % in the general population. BRCA1 breast cancers typically have an aggressive course (i.e., high-grade, triple-negative) and are associated with a poor prognosis. At present, primary prevention is limited to prophylactic removal of the unaffected breasts. Effective chemopreventive strategies are not yet available. Emerging evidence suggests that BRCA1 mutation carriers have high circulating levels of progesterone which may play a role in their susceptibility to breast cancer. Recently, the RANK/RANKL system was found to be dysregulated in women with a BRCA1 mutation. Mutation carriers had significantly lower endogenous levels of osteoprotegerin (OPG) than women without a BRCA1 mutation. OPG is an endogenous decoy receptor for RANKL and inhibits RANKL-mediated signaling. RANKL binds to RANK on mammary epithelial cells and stimulates their proliferation and maturation. Low OPG levels may contribute to mammary tumorigenesis through increased proliferation and may explain in part the increased breast cancer risk in BRCA1 mutation carriers. Denosumab is an anti-RANKL monoclonal antibody which is approved to treat osteoporosis and to prevent skeletal damage caused by bone metastases. The emerging role of aberrant RANK-signaling in BRCA1 tumorigenesis suggests that targeting of RANKL may prevent breast cancer among women with germline BRCA1 mutations. Clinical investigations of denosumab are warranted and may lead to a novel chemopreventive approach for breast cancer for high-risk women.

Topics: Biomarkers; BRCA1 Protein; Breast Neoplasms; Cell Transformation, Neoplastic; Chemoprevention; Disease Management; Female; Heterozygote; Humans; Mutation; Osteoprotegerin; Progesterone; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Signal Transduction

RANK and its ligand RANKL are key molecules in bone metabolism and are critically involved in pathologic bone disorders. Deregulation of the RANK/RANKL system is for example a main reason for the development of postmenopausal osteoporosis, which affects millions of women worldwide. Another essential function of RANK and RANKL is the development of a functional lactating mammary gland during pregnancy. Sex hormones, in particular progesterone, induce RANKL expression resulting in proliferation of mammary epithelial cells. Moreover, RANK and RANKL have been shown to regulate mammary epithelial stem cells. RANK and RANKL were also identified as critical mechanism in the development of hormone-induced breast cancer and metastatic spread to bone. In this review, we will focus on the various RANK/RANKL functions ranging from bone physiology, immune regulation, and initiation of breast cancer.

Topics: Animals; Autoimmune Diseases; Bone and Bones; Bone Diseases; Bone Neoplasms; Breast Neoplasms; Cell Transformation, Neoplastic; Female; Humans; Mice; NF-kappa B; Osteoporosis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B

Having defined a putative anticarcinogenic principle under physiological conditions of the auditory inner ear in the previous part of this study, part 2 is the continuation to evaluate this hypothesis under pathological conditions, i.e. with regard to the inflamed auditory inner ear. Inflammation of the auditory inner ear shows three characteristic phases. It starts with an acute phase, progresses to a fibrotic one and ends with ossification as the last phase. At the end of the fibrotic phase the inflammatory cells disappear, probably due to apoptosis, the ganglion neurons die and the fibrous matrix ossifies. No proliferating cells can be found in this area any more. Thus this kind of inflammation does not result in a restoration of the former state, but always in the destruction of the hearing organ and corresponding neurons. The osteoimmune axis is involved in this characteristic type of inflammation. Important factors hereby are M-CSF, RANKL/RANK and osteoprotegerin. In the inner auditory ear they inhibit the resorption of the fibrotic matrix, induce apoptosis of inflammatory cells and calcification. This inflammatory osteoimmune axis plays an important role at the cancer site as well. The relation of each factor to the other ones is however fundamentally different from that in the inner ear. Consequently inflammatory processes induced by a tumour foster its progression and may induce bone metastasis. Instead of a dominating and enclosing osteoblastic activity like in the inner ear, matrix resolving and often osteoclastic properties are developed allowing the spread of cancer cells. These processes allows us to set out the anticarcinogenic hypothesis more precisely and define its putative mechanistic rationale for the inflamed auditory inner ear.

Topics: Animals; Bone and Bones; Cell Transformation, Neoplastic; Ear Neoplasms; Ear, Inner; Hair Cells, Auditory, Inner; Humans; Labyrinthitis; Macrophage Colony-Stimulating Factor; Neoplasms; Ossification, Heterotopic; Osteoblasts; Osteoprotegerin; RANK Ligand

The emergence of the molecular triad osteoprotegerin (OPG)/Receptor Activator of NF-kB (RANK)/RANK Ligand (RANKL) has helped elucidate a key signalling pathway between stromal cells and osteoclasts. The interaction between RANK and RANKL plays a critical role in promoting osteoclast differentiation and activation leading to bone resorption. OPG is a soluble decoy receptor for RANKL that blocks osteoclast formation by inhibiting RANKL binding to RANK. The OPG/RANK/RANKL system has been shown to be abnormally regulated in several malignant osteolytic pathologies such as multiple myeloma [MM, where enhanced RANKL expression (directly by tumour cells or indirectly by stromal bone cells or T-lymphocytes)] plays an important role in associated bone destruction. By contrast, production of its endogenous counteracting decoy receptor OPG is either inhibited or too low to compensate for the increase in RANKL production. Therefore, targeting the OPG/RANK/RANKL axis may offer a novel therapeutic approach to malignant osteolytic pathologies. In animal models, OPG or soluble RANK was shown both to control hypercalcaemia of malignancy and the establishment and progression of osteolytic metastases caused by various malignant tumours. To this day, only one phase I study has been performed using a recombinant OPG construct that suppressed bone resorption in patients with multiple myeloma or breast carcinoma with radiologically confirmed bone lesions. RANK-Fc also exhibits promising therapeutic effects, as revealed in animal models of prostate cancer and multiple myeloma. If the animal results translate to similar clinical benefits in humans, using RANK-Fc or OPG may yield novel and potent strategies for treating patients with established or imminent malignant bone diseases and where standard therapeutic regimens have failed.

Topics: Antineoplastic Agents; Bone Neoplasms; Carrier Proteins; Cell Transformation, Neoplastic; Glycoproteins; Humans; Membrane Glycoproteins; Multiple Myeloma; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Signal Transduction

Synovial sarcoma (SS) is an aggressive soft-tissue sarcoma that is often discovered during adolescence and young adulthood. Despite the name, synovial sarcoma does not typically arise from a synoviocyte but instead arises in close proximity to bones. Previous work demonstrated that mice expressing the characteristic SS18-SSX fusion oncogene in myogenic factor 5-expressing (Myf5-expressing) cells develop fully penetrant sarcomagenesis, suggesting skeletal muscle progenitor cell origin. However, Myf5 is not restricted to committed myoblasts in embryos but is also expressed in multipotent mesenchymal progenitors. Here, we demonstrated that human SS and mouse tumors arising from SS18-SSX expression in the embryonic, but not postnatal, Myf5 lineage share an anatomic location that is frequently adjacent to bone. Additionally, we showed that SS can originate from periosteal cells expressing SS18-SSX alone and from preosteoblasts expressing the fusion oncogene accompanied by the added stabilization of β-catenin, which is a common secondary change in SS. Expression and secretion of the osteoclastogenesis inhibitory factor osteoprotegerin enabled early growth of SS18-SSX2-transformed cells, indicating a paracrine link between the bone and synovial sarcomagenesis. These findings explain the skeletal contact frequently observed in human SS and may provide alternate means of enabling SS18-SSX-driven oncogenesis in cells as differentiated as preosteoblasts.

Topics: Animals; beta Catenin; Bone Neoplasms; Cell Transformation, Neoplastic; Humans; Mice; Mice, Knockout; Oncogene Proteins, Fusion; Osteoblasts; Osteoprotegerin; Paracrine Communication; Periosteum; Proto-Oncogene Proteins; Repressor Proteins; Sarcoma, Synovial

It is widely recognized that inflammation promotes breast cancer invasion and metastasis. Given the complex nature of the breast tumor inflammatory microenvironment, much remains to be understood of the molecular mechanisms that govern these effects. We have previously shown that osteoprotegerin knockdown in breast cancer cells resulted in reduced invasion and metastasis. Here we present novel insight into the role of osteoprotegerin in inflammation-driven tumor progression in breast cancer by investigating the link between osteoprotegerin, macrophages and the potent pro-inflammatory cytokine Interleukin-1beta.. We used human breast cancer cell lines to investigate the effects of Interleukin-1beta treatment on osteoprotegerin secretion as measured by ELISA. We analyzed public datasets containing human breast cancer genome-wide mRNA expression data to reveal a significant and positive correlation between osteoprotegerin mRNA expression and the mRNA expression of Interleukin-1beta and of monocyte chemoattractant protein CC-chemokine ligand 2. Osteoprotegerin, Interleukin-1beta and CC-chemokine ligand 2 mRNA levels were also examined by qPCR on cDNA from normal and cancerous human breast tissue. We determined the effect of Interleukin-1beta-producing macrophages on osteoprotegerin expression by co-culturing breast cancer cells and differentiated THP-1 macrophages. Immunohistochemistry was performed on human breast tumor tissue microarrays to assess macrophage infiltration and osteoprotegerin expression. To demonstrate that osteoprotegerin mediated functional effects of Interleukin-1beta we performed cell invasion studies with control and OPG siRNA knockdown on Interleukin-1beta-treated breast cancer cells.. We report that Interleukin-1beta induces osteoprotegerin secretion, independent of breast cancer subtype and basal osteoprotegerin levels. Co-culture of breast cancer cells with Interleukin-1beta-secreting macrophages resulted in a similar increase in osteoprotegerin secretion in breast cancer cells as Interleukin-1beta treatment. Macrophage infiltration correlates with osteoprotegerin secretion in human breast tumor tissue samples. We show that osteoprotegerin secretion is regulated by Interleukin-1beta in a p38- and p42/44-dependent manner. We also demonstrate that osteoprotegerin knockdown represses Interleukin-1beta expression, Interleukin-1beta-mediated breast cancer cell invasion and MMP3 expression.. These data indicate a novel role for osteoprotegerin as a mediator of inflammation- promoted breast cancer progression.

Topics: Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Transformation, Neoplastic; Coculture Techniques; Computational Biology; Cytokines; Databases, Genetic; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Inflammation Mediators; Interleukin-1beta; Macrophages; MAP Kinase Signaling System; Osteoprotegerin; Tumor Microenvironment

Breast cancer development in BRCA1/2 mutation carriers is a net consequence of cell-autonomous and cell nonautonomous factors which may serve as excellent targets for cancer prevention. In light of our previous data we sought to investigate the consequences of the BRCA-mutation carrier state on RANKL/osteoprotegerin (OPG) signalling. We analysed serum levels of RANKL, OPG, RANKL/OPG complex, oestradiol (E2), and progesterone (P) during menstrual cycle progression in 391 BRCA1/2-mutation carriers and 782 noncarriers. These studies were complemented by analyses of RANKL and OPG in the serum and mammary tissues of female cynomolgus macaques (n = 88) and serum RANKL and OPG in postmenopausal women (n = 150). BRCA-mutation carriers had lower mean values of free serum OPG in particular in BRCA1-mutation carriers (p = 0.018) compared with controls. Among BRCA1/2 mutation carriers, lower OPG levels were associated with germline mutation locations known to confer an increased breast cancer risk (p = 0.003). P is associated with low OPG levels in serum and tissue, particularly in BRCA-mutation carriers (rho = - 0.216; p = 0.002). Serum OPG levels were inversely correlated (rho = - 0.545, p < 0.001) with mammary epithelial proliferation measured by Ki67 expression and increased (p = 0.01) in postmenopause. The P-RANKL/OPG system is dysregulated in BRCA-mutation carriers. These and previously published data provide a strong rationale for further investigation of antiprogestogens or an anti-RANKL antibody such as denosumab for breast cancer prevention.

Topics: Animals; Case-Control Studies; Cell Transformation, Neoplastic; Female; Gene Expression Regulation, Neoplastic; Genes, BRCA1; Genes, BRCA2; Germ-Line Mutation; Hereditary Breast and Ovarian Cancer Syndrome; Heterozygote; Hormones; Humans; Macaca fascicularis; Mutation; Osteoprotegerin; Patient Outcome Assessment; Postmenopause; RANK Ligand; Risk Factors

Receptor activator of nuclear factor-kappa B ligand (RANKL) is a TNF ligand superfamily member that is essential for the formation, activation, and function of osteoclasts. RANKL functions via its cognate receptor RANK, and it is inhibited by the soluble decoy receptor osteoprotegerin (OPG). In skeletal metastases, the ratio of RANKL to OPG is upregulated, which leads to increased osteoclast-mediated bone destruction. These changes in the bone microenvironment not only compromise the structural integrity of bone, leading to severe clinical morbidities, but have also been implicated in establishment of de novo bone metastasis and the progression of existing skeletal tumors. Evaluation of RANKL inhibitors, including the fully human anti-RANKL antibody denosumab, in patients with cancer has shown reductions in tumor-induced bone resorption activity and successful management of skeletal complications of bone metastases. RANKL also functions as a major paracrine effector of the mitogenic action of progesterone in mouse mammary epithelium, and it has a role in ovarian hormone-dependent expansion and regenerative potential of mammary stem cells. RANKL inhibition attenuates mammary tumorigenesis and pulmonary metastases in mouse models. These data suggest that the contribution of progesterone to increased mammary cancer incidence is mediated, at least in part, by RANKL-dependent changes in the mammary epithelium; RANKL also directly promotes distant metastases. In summary, the antitumor and antimetastatic effects of RANKL inhibition can occur by at least 2 distinct mechanisms, one in the bone via osteoclast-dependent effects, and the second via direct effects on the tumor cells of various origins and/or mammary epithelium.

Topics: Animals; Bone and Bones; Bone Neoplasms; Breast Neoplasms; Cell Transformation, Neoplastic; Humans; Osteoclasts; Osteoporosis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Signal Transduction

Giant cell tumor (GCT) of bone is a primary osteolytic tumor that is characterized by the formation of osteoclast-like giant cells. In addition to GCT of bone, extraskeletal GCT are known to be formed in several soft tissues. Giant cells in GCT of bone were suggested to be identical to osteoclasts, but the characterization of giant cells in extraskeletal GCT remains incomplete. In this study, a case of sarcomatoid hepatocellular carcinoma with osteoclast-like giant cells was analyzed. Immunohistochemistry revealed the expression of almost all markers of osteoclasts: tartrate-resistant acid phosphatase, CD68, CD51, CD54 and matrix metalloprotease-9, in osteoclast-like giant cells in the tumor. In situ hybridization revealed the expression of receptor activator of nuclear factor-kappa B (RANK) in the giant cells and receptor activator of nuclear factor-kappa B ligand (RANKL) in the tumor cells. The hepatic origin of the sarcomatoid hepatocellular carcinoma cells was confirmed by the expression of albumin. This is the first report suggesting that hepatocyte-derived cells possess the potential for osteoclastogenesis. In addition, these findings suggest that osteoclast-like cells in the hepatocellular carcinoma were formed by the same mechanism as osteoclastogenesis in bone.

Topics: Aged; Albumins; Biomarkers; Carcinoma, Hepatocellular; Carcinosarcoma; Carrier Proteins; Cell Transformation, Neoplastic; Fatal Outcome; Giant Cells; Glycoproteins; Hepatocytes; Humans; Immunohistochemistry; In Situ Hybridization; Liver Neoplasms; Male; Membrane Glycoproteins; Osteoclasts; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger