Prostate cancer (PCa) is one of the major public health problems in Western countries. Recently, the TMPRSS2:ERG gene fusion, which results in the aberrant expression of the transcription factor ERG, ...has been shown to be the most common gene rearrangement in PCa. Previous studies have determined the contributions of this fusion in PCa disease initiation and/or progression in vitro and in vivo. In this study on TMPRSS2:ERG regulation in PCa, we used an androgen receptor and TMPRSS2:ERG fusion double-negative PCa cell model: PC3c. In three cell clones with different TMPRSS2:ERG expression levels, ectopic expression of the fusion resulted in significant induction of cell migration and invasion in a dose-dependent manner. In agreement with this phenotype, high-throughput microarray analysis revealed that a set of genes, functionally associated with cell motility and invasiveness, were deregulated in a dose-dependent manner in TMPRSS2:ERG-expressing cells. Importantly, we identified increased MMP9 (Metalloproteinase 9) and PLXNA2 (Plexin A2) expression in TMPRSS2:ERG-positive PCa samples, and their expression levels were significantly correlated with ERG expression in a PCa cohort. In line with these findings, there was evidence that TMPRSS2:ERG directly and positively regulates MMP9 and PLXNA2 expression in PC3c cells. Moreover, PLXNA2 upregulation contributed to TMPRSS2:ERG-mediated enhancements of PC3c cell migration and invasion. Furthermore, and importantly, PLXNA2 expression was upregulated in metastatic PCa tumors compared with localized primary PCa tumors. This study provides novel insights into the role of the TMPRSS2:ERG fusion in PCa metastasis.
Bone is the most common metastatic site for breast cancer. Estrogen-related-receptor alpha (ERRα) has been implicated in cancer cell invasiveness. Here, we established that ERRα promotes spontaneous ...metastatic dissemination of breast cancer cells from primary mammary tumors to the skeleton. We carried out cohort studies, pharmacological inhibition, gain-of-function analyses in vivo and cellular and molecular studies in vitro to identify new biomarkers in breast cancer metastases. Meta-analysis of human primary breast tumors revealed that high ERRα expression levels were associated with bone but not lung metastases. ERRα expression was also detected in circulating tumor cells from metastatic breast cancer patients. ERRα overexpression in murine 4T1 breast cancer cells promoted spontaneous bone micro-metastases formation when tumor cells were inoculated orthotopically, whereas lung metastases occurred irrespective of ERRα expression level. In vivo, Rank was identified as a target for ERRα. That was confirmed in vitro in Rankl stimulated tumor cell invasion, in mTOR/pS6K phosphorylation, by transactivation assay, ChIP and bioinformatics analyses. Moreover, pharmacological inhibition of ERRα reduced primary tumor growth, bone micro-metastases formation and Rank expression in vitro and in vivo. Transcriptomic studies and meta-analysis confirmed a positive association between metastases and ERRα/RANK in breast cancer patients and also revealed a positive correlation between ERRα and BRCA1
carriers. Taken together, our results reveal a novel ERRα/RANK axis by which ERRα in primary breast cancer promotes early dissemination of cancer cells to bone. These findings suggest that ERRα may be a useful therapeutic target to prevent bone metastases.
In just 3 years, striking new advances have been made in understanding the molecular mechanisms that govern the crosstalk between osteoblasts/stromal cells and hematopoietic osteoclast precursor ...cells that leads to osteoclastogenesis. Led first by the discovery of osteoprotegerin (OPG), a naturally occurring protein with potent osteoclastogenesis inhibitory activity, rapid progress was made to the isolation of RANKL, a transmembrane ligand expressed on osteoblasts/stromal cells that binds to RANK, a transmembrane receptor on hematopoietic osteoclast precursor cells. The interaction of RANK and RANKL initiates a signaling and gene expression cascade that results in differentiation and maturation of osteoclast precursor cells to active osteoclasts capable of resorbing bone. OPG acts as a decoy receptor, binding to RANKL and blocking its interaction with RANK, inhibiting osteoclast development. Many of the calciotropic hormones and cytokines, including 1,25(OH)2D3, PTH, PGE2 and IL-11, appear to act through a dual capacity to inhibit production of OPG and stimulate production of RANKL. Estrogen, on the other hand, appears to inhibit production of RANKL and RANKL-stimulated osteoclastogenesis. Recently, the results of the first clinical trial with OPG supported its potential as a therapeutic agent for diseases such as osteoporosis. The new understanding provided by the RANK/RANKL/OPG paradigm for both differentiation of osteoclasts and their activation has had tremendous impact on the field and opened new avenues for development of possible treatments of diseases characterized by excessive bone resorption.
•Matrix protein periostin is involved in cancer cell dissemination and bone response.•Serum periostin level was higher in adenocarcinoma lung cancer patients with bone metastases than in patients ...with localized tumor.•High periostin was an independent poor prognosis survival biomarker in bone metastatic adenocarcinoma lung cancer patients.•In bone metastases, periostin was expressed in microenvironment and in cancer cells at nuclear and cytoplasmic location.
More than 35% of lung adenocarcinoma patients have bone metastases at diagnosis and have a poor survival. Periostin, a carboxylated matrix protein, mediates lung cancer cell dissemination by promoting epithelial-mesenchymal transition, and is involved in bone response to mechanical stress and bone formation regulation. This suggests that periostin may be used as a biomarker to predict survival in lung cancer patients.
Serum periostin was assessed at diagnosis in a prospective cohort of 133 patients with lung adenocarcinoma of all stages. Patients were divided into localized and bone metastatic groups. Both groups were matched to healthy controls. Survival analysis and Cox proportional hazards models were conducted in the total population and in bone metastatic group.
The median serum periostin level was higher in bone metastatic (n = 67; median: 1752 pmol/L) than in the localized group (n = 66; 861 pmol/L; p < 0.0001). Patients with high periostin (>median) had a poorer overall survival in the whole population (33.3 weeks vs. NR; p < 0.0001) and the bone metastatic group (24.4 vs. 66.1 weeks; p < 0.001). In multivariate analysis, patients with high periostin had increased risk of death (HR = 2.09, 95%CI 1.06–4.13; p = 0.03). This was also found in the bone metastatic group (HR = 3.62, 95%CI 1.74–7.52; p = 0.0005). Immunohistochemistry on bone metastasis biopsies showed periostin expression in the bone matrix and nuclear and cytoplasmic staining in cancer cells.
Serum periostin was an independent survival biomarker in all-stage and in bone metastatic lung adenocarcinoma patients. IHC data suggest that periostin might be induced in cancer cells in bone metastatic niche in addition to bone microenvironment expression.
Periostin is an extracellular matrix protein that actively contributes to tumor progression and metastasis. Here, we hypothesized that it could be a marker of bone metastasis formation. To address ...this question, we used two polyclonal antibodies directed against the whole molecule or its C-terminal domain to explore the expression of intact and truncated forms of periostin in the serum and tissues (lung, heart, bone) of wild-type and periostin-deficient mice. In normal bones, periostin was expressed in the periosteum and specific periostin proteolytic fragments were found in bones, but not in soft tissues. In animals bearing osteolytic lesions caused by 4T1 cells, C-terminal intact periostin (iPTN) expression disappeared at the invasive front of skeletal tumors where bone-resorbing osteoclasts were present. In vitro, we found that periostin was a substrate for osteoclast-derived cathepsin K, generating proteolytic fragments that were not recognized by anti-periostin antibodies directed against iPTN. In vivo, using an in-house sandwich immunoassay aimed at detecting iPTN only, we observed a noticeable reduction of serum periostin levels (− 26%;
P
< 0.002) in animals bearing osteolytic lesions caused by 4T1 cells. On the contrary, this decrease was not observed in women with breast cancer and bone metastases when periostin was measured with a human assay detecting total periostin. Collectively, these data showed that mouse periostin was degraded at the bone metastatic sites, potentially by cathepsin K, and that the specific measurement of iPTN in serum should assist in detecting bone metastasis formation in breast cancer.
Estrogen receptor-related receptor-α (ERRα) is an orphan nuclear receptor with sequence homology to the estrogen receptors, ERα/β, but it does not bind estrogen. However, several recent studies ...suggest that ERRα not only plays a functional role in osteoblasts but also impinges on the estrogen axis in bone, as it does in at least certain other estrogen target tissues. We summarize here data on ERRα and its cellular and molecular modes of action that have broad implications for considering the potential role of this orphan receptor as a new therapeutic target in osteopenic disorders such as osteoporosis as well as other estrogen-responsive conditions.
Abstract Strontium ranelate is a newly developed drug that has been shown to significantly reduce the risk of vertebral and non-vertebral fractures, including those of the hip, in postmenopausal ...women with osteoporosis. In contrast to other available treatments for osteoporosis, strontium ranelate increases bone formation and decreases resorption. In this study, the dual mode of action of strontium ranelate in bone was tested in vitro , on primary murine osteoblasts and osteoclasts derived from calvaria and spleen cells, respectively. We show that strontium ranelate treatment, either continuously or during proliferation or differentiation phases of mouse calvaria cells, stimulates osteoblast formation. Indeed after 22 days of continuous treatment with strontium ranelate, the expression of the osteoblast markers ALP, BSP and OCN was increased, and was combined with an increase in bone nodule numbers. On the other hand, the number of mature osteoclasts strongly decreased after strontium ranelate treatment. Similarly to previous studies, we confirm that osteoclasts resorbing activity was also reduced but we found that strontium ranelate treatment was associated with a disruption of the osteoclast actin-containing sealing zone. Therefore, our in vitro assays performed on primary murine bone cells confirmed the dual action of strontium ranelate in vivo as an anabolic agent on bone remodeling. It stimulates bone formation through its positive action on osteoblast differentiation and function, and decreases osteoclast differentiation as well as function by disrupting actin cytoskeleton organization.
Objectives. Subchondral bone loss is a characteristic feature of inflammatory arthritis. Recently, estrogen receptor-related receptor-α (ERR-α), an orphan nuclear receptor, has been found to be ...involved in activation of macrophages. We hypothesized that ERR-α which is expressed and also functional in articular chondrocytes, osteoblasts and osteoclasts, may be involved in rodent models of inflammatory arthritis. Methods. Erosive arthritis was induced in DBA/1 mice by injection of type II collagen in Freund's complete adjuvant. RNA was isolated from the bone and joints and expression of ERR-α and cartilage (GDF5 and Col2a1) and bone bone sialoprotein (BSP) and osteocalcin (OCN) markers was analysed by semi-quantitative PCR. Results. We report for the first time that the expression of ERR-α is dysregulated in bones and joints in a mouse model of inflammatory arthritis. Specifically, we show that ERR-α expression is down-regulated early in bone and later in joints of mice with type II CIA. Concomitantly, temporal changes were observed in GDF-5 and Col2a1 expression in joints following both initial injection and booster injection of type II collagen. Similarly, down-regulation of ERR-α mRNA expression in subchondral bone in mice with induced joint inflammation was also paralleled by down-regulation of markers of bone formation (BSP, OCN). Conclusions. These data suggest that dysregulation of ERR-α expression may precede and contribute to the destruction of cartilage and bone accompanying inflammatory arthritis.
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