Interactions between microenvironment and cancer cells in two animal models of bone metastasis

The preferential proliferation of cancer cells in the bone microenvironment is poorly characterised. Expression pattern of bone marrow and other organ microenvironment in contact with osteolytic (Walker W256) and osteoblastic (MatLyLu MLL) metastases were investigated. Fisher and Copenhagen rats received, respectively, W256 and MLL cells injection. Bone and soft tissues were analysed by immunochemistry for DKK1, cathepsin K, RANKL, MCSF or IL6 expression. Tartrate-resistant acid phosphatase (TRAcP)-positive cells were detected by a histoenzymatic technique. In bone, expressions of MCSF and DKK1 were shown in stromal cells of the bone marrow, in contact with metastatic foci of both tumours. Many stromal cells were found RANKL positive in the vicinity of the tumours. Cells expressing cathepsin K and multinucleated TRAcP+ cells were found in direct contact with trabeculae but also in bone marrow spaces near metastatic cells. In extraosseous tumours, cells in contact with malignant cells did not expressed DKK1, MCSF, cathepsin K and IL6. Some RANKL+ cells were found in the periphery of subcutaneous tumours but may represent Langerhans cells. Abnormal presence of TRAcP+ cells was never observed in the vicinity of malignant cells. Interaction between stromal and cancer cells induces the expression on the formers of characteristics leading to osteoclastogenesis only in the bone microenvironment

Epidermal growth factor signalling and bone metastasis

Epidermal growth factor (EGF) signalling is well known for its multifaceted functions in development and tissue homoeostasis. The EGF family of ligands and receptors (ERBB family) have also been extensively investigated for their roles in promoting tumourigenesis and metastasis in a variety of cancer types. Recent findings indicate that EGF signalling is an important mediator of bone metastasis in breast, prostate and kidney cancers. The EGF signalling stimulates the growth of bone metastasis directly by increasing tumour cell proliferation and indirectly by engaging bone stromal cell in metastasis-promoting activities. Therefore, molecular targeting of ERBB receptors may benefit patients with bone metastasis and should be evaluated in clinical trials

A Cross-Species Analysis of a Mouse Model of Breast Cancer-Specific Osteolysis and Human Bone Metastases Using Gene Expression Profiling

<p>Abstract</p> <p>Background</p> <p>Breast cancer is the second leading cause of cancer-related death in women in the United States. During the advanced stages of disease, many breast cancer patients suffer from bone metastasis. These metastases are predominantly osteolytic and develop when tumor cells interact with bone. <it>In vivo </it>models that mimic the breast cancer-specific osteolytic bone microenvironment are limited. Previously, we developed a mouse model of tumor-bone interaction in which three mouse breast cancer cell lines were implanted onto the calvaria. Analysis of tumors from this model revealed that they exhibited strong bone resorption, induction of osteoclasts and intracranial penetration at the tumor bone (TB)-interface.</p> <p>Methods</p> <p>In this study, we identified and used a TB microenvironment-specific gene expression signature from this model to extend our understanding of the metastatic bone microenvironment in human disease and to predict potential therapeutic targets.</p> <p>Results</p> <p>We identified a TB signature consisting of 934 genes that were commonly (among our 3 cell lines) and specifically (as compared to tumor-alone area within the bone microenvironment) up- and down-regulated >2-fold at the TB interface in our mouse osteolytic model. By comparing the TB signature with gene expression profiles from human breast metastases and an <it>in vitro </it>osteoclast model, we demonstrate that our model mimics both the human breast cancer bone microenvironment and osteoclastogenesis. Furthermore, we observed enrichment in various signaling pathways specific to the TB interface; that is, TGF-β and myeloid self-renewal pathways were activated and the Wnt pathway was inactivated. Lastly, we used the TB-signature to predict cyclopenthiazide as a potential inhibitor of the TB interface.</p> <p>Conclusion</p> <p>Our mouse breast cancer model morphologically and genetically resembles the osteoclastic bone microenvironment observed in human disease. Characterization of the gene expression signature specific to the TB interface in our model revealed signaling mechanisms operative in human breast cancer metastases and predicted a therapeutic inhibitor of cancer-mediated osteolysis.</p

Administration of zoledronic acid enhances the effects of docetaxel on growth of prostate cancer in the bone environment

BACKGROUND: After development of hormone-refractory metastatic disease, prostate cancer is incurable. The recent history of chemotherapy has shown that with difficult disease targets, combinatorial therapy frequently offers the best chance of a cure. In this study we have examined the effects of a combination of zoledronic acid (ZOL), a new-generation bisphosphonate, and docetaxel on LuCaP 23.1, a prostate cancer xenograft that stimulates the osteoblastic reaction when grown in the bone environment. METHODS: Intra-tibial injections of LuCaP 23.1 cells were used to generate tumors in the bone environment, and animals were treated with ZOL, docetaxel, or a combination of these. Effects on bone and tumor were evaluated by measurements of bone mineral density and histomorphometrical analysis. RESULTS: ZOL decreased proliferation of LuCaP 23.1 in the bone environment, while docetaxel at a dose that effectively inhibited growth of subcutaneous tumors did not show any effects in the bone environment. The combination of the drugs significantly inhibited the growth of LuCaP 23.1 tumors in the bone. CONCLUSION: In conclusion, the use of the osteolysis-inhibitory agent ZOL in combination with docetaxel inhibits growth of prostate tumors in bone and represents a potential treatment option

The Role of Alpha 6 Integrin in Prostate Cancer Migration and Bone Pain in a Novel Xenograft Model

Of the estimated 565,650 people in the U.S. who will die of cancer in 2008, almost all will have metastasis. Breast, prostate, kidney, thyroid and lung cancers metastasize to the bone. Tumor cells reside within the bone using integrin type cell adhesion receptors and elicit incapacitating bone pain and fractures. In particular, metastatic human prostate tumors express and cleave the integrin A6, a receptor for extracellular matrix components of the bone, i.e., laminin 332 and laminin 511. More than 50% of all prostate cancer patients develop severe bone pain during their remaining lifetime. One major goal is to prevent or delay cancer induced bone pain. We used a novel xenograft mouse model to directly determine if bone pain could be prevented by blocking the known cleavage of the A6 integrin adhesion receptor. Human tumor cells expressing either the wildtype or mutated A6 integrin were placed within the living bone matrix and 21 days later, integrin expression was confirmed by RT-PCR, radiographs were collected and behavioral measurements of spontaneous and evoked pain performed. All animals independent of integrin status had indistinguishable tumor burden and developed bone loss 21 days after surgery. A comparison of animals containing the wild type or mutated integrin revealed that tumor cells expressing the mutated integrin resulted in a dramatic decrease in bone loss, unicortical or bicortical fractures and a decrease in the ability of tumor cells to reach the epiphyseal plate of the bone. Further, tumor cells within the bone expressing the integrin mutation prevented cancer induced spontaneous flinching, tactile allodynia, and movement evoked pain. Preventing A6 integrin cleavage on the prostate tumor cell surface decreased the migration of tumor cells within the bone and the onset and degree of bone pain and fractures. These results suggest that strategies for blocking the cleavage of the adhesion receptors on the tumor cell surface can significantly prevent cancer induced bone pain and slow disease progression within the bone. Since integrin cleavage is mediated by Urokinase-type Plasminogen Activator (uPA), further work is warranted to test the efficacy of uPA inhibitors for prevention or delay of cancer induced bone pain

Unauthorized Horizontal Spread in the Laboratory Environment: The Tactics of Lula, a Temperate Lambdoid Bacteriophage of Escherichia coli

We investigated the characteristics of a lambdoid prophage, nicknamed Lula, contaminating E. coli strains from several sources, that allowed it to spread horizontally in the laboratory environment. We found that new Lula infections are inconspicuous; at the same time, Lula lysogens carry unusually high titers of the phage in their cultures, making them extremely infectious. In addition, Lula prophage interferes with P1 phage development and induces its own lytic development in response to P1 infection, turning P1 transduction into an efficient vehicle of Lula spread. Thus, using Lula prophage as a model, we reveal the following principles of survival and reproduction in the laboratory environment: 1) stealth (via laboratory material commensality), 2) stability (via resistance to specific protocols), 3) infectivity (via covert yet aggressive productivity and laboratory protocol hitchhiking). Lula, which turned out to be identical to bacteriophage phi80, also provides an insight into a surprising persistence of T1-like contamination in BAC libraries

Prominent Bone Loss Mediated by RANKL and IL-17 Produced by CD4+ T Cells in TallyHo/JngJ Mice

Increasing evidence that decreased bone density and increased rates of bone fracture are associated with abnormal metabolic states such as hyperglycemia and insulin resistance indicates that diabetes is a risk factor for osteoporosis. In this study, we observed that TallyHo/JngJ (TH) mice, a polygenic model of type II diabetes, spontaneously developed bone deformities with osteoporotic features. Female and male TH mice significantly gained more body weight than control C57BL/6 mice upon aging. Interestingly, bone density was considerably decreased in male TH mice, which displayed hyperglycemia. The osteoblast-specific bone forming markers osteocalcin and osteoprotegerin were decreased in TH mice, whereas osteoclast-driven bone resorption markers such as IL-6 and RANKL were significantly elevated in the bone marrow and blood of TH mice. In addition, RANKL expression was prominently increased in CD4+ T cells of TH mice upon T cell receptor stimulation, which was in accordance with enhanced IL-17 production. IL-17 production in CD4+ T cells was directly promoted by treatment with leptin while IFN-γ production was not. Moreover, blockade of IFN-γ further increased RANKL expression and IL-17 production in TH-CD4+ T cells. In addition, the osteoporotic phenotype of TH mice was improved by treatment with alendronate. These results strongly indicate that increased leptin in TH mice may act in conjunction with IL-6 to preferentially stimulate IL-17 production in CD4+ T cells and induce RANKL-mediated osteoclastogenesis. Accordingly, we propose that TH mice could constitute a beneficial model for osteoporosis

Lazarus1, a DUF300 Protein, Contributes to Programmed Cell Death Associated with Arabidopsis acd11 and the Hypersensitive Response

Programmed cell death (PCD) is a necessary part of the life of multi-cellular organisms. A type of plant PCD is the defensive hypersensitive response (HR) elicited via recognition of a pathogen by host resistance (R) proteins. The lethal, recessive accelerated cell death 11 (acd11) mutant exhibits HR-like accelerated cell death, and cell death execution in acd11 shares genetic requirements for HR execution triggered by one subclass of R proteins

Inhibition of epidermal growth factor receptor signalling reduces hypercalcaemia induced by human lung squamous-cell carcinoma in athymic mice

The purpose of this study was to evaluate the role of the epidermal growth factor receptor (EGFR) in parathyroid hormone-related protein (PTHrP) expression and humoral hypercalcaemia of malignancy (HHM), using two different human squamous-cell carcinoma (SCC) xenograft models. A randomised controlled study in which nude mice with RWGT2 and HARA xenografts received either placebo or gefitinib 200 mg kg−1 for 3 days after developing HHM. Effectiveness of therapy was evaluated by measuring plasma calcium and PTHrP, urine cyclic AMP/creatinine ratios, and tumour volumes. The study end point was at 78 h. The lung SCC lines, RWGT2 and HARA, expressed high levels of PTHrP mRNA as well as abundant EGFR protein, but very little erbB2 or erbB3. Both lines expressed high transcript levels for the EGFR ligand, amphiregulin (AREG), as well as, substantially lower levels of transforming growth factor-α (TGF-α), and heparin binding-epidermal growth factor (HB-EGF) mRNA. Parathyroid hormone-related protein gene expression in both lines was reduced 40–80% after treatment with 1 μM of EGFR tyrosine kinase inhibitor PD153035 and precipitating antibodies to AREG. Gefitinib treatment of hypercalcaemic mice with RWGT2 and HARA xenografts resulted in a significant reduction of plasma total calcium concentrations by 78 h. Autocrine AREG stimulated the EGFR and increased PTHrP gene expression in the RWGT2 and HARA lung SCC lines. Inhibition of the EGFR pathway in two human SCC models of HHM by an anilinoquinazoline demonstrated that the EGFR tyrosine kinase is a potential target for antihypercalcaemic therapy

RANK, RANKL and osteoprotegerin in bone biology and disease

Upon the discovery of RANK, RANKL and OPG in the late 1990s, their importance in the maintenance of the skeletal structure and their dramatic role in bone disease were largely unexpected. In recent years the understanding of these proteins, in particular their regulation, has greatly increased. This review aims to bring the interested reader up to date with the latest news and views on the mechanisms controlling bone resorption in normal and pathological conditions