Halofuginone inhibits TGF-β/BMP signaling and in combination with zoledronic acid enhances inhibition of breast cancer bone metastasis.

More efficient therapies that target multiple molecular mechanisms are needed for the treatment of incurable bone metastases. Halofuginone is a plant alkaloid-derivative with antiangiogenic and antiproliferative effects. Here we demonstrate that halofuginone is an effective therapy for the treatment of bone metastases, through multiple actions that include inhibition of TGFβ and BMP-signaling.

Aromatase inhibitor-induced bone loss increases the progression of estrogen receptor-negative breast cancer in bone and exacerbates muscle weakness in vivo.

Aromatase inhibitors (AIs) cause muscle weakness, bone loss, and joint pain in up to half of cancer patients. Preclinical studies have demonstrated that increased osteoclastic bone resorption can impair muscle contractility and prime the bone microenvironment to accelerate metastatic growth. We hypothesized that AI-induced bone loss could increase breast cancer progression in bone and exacerbate muscle weakness associated with bone metastases.

Excess TGF-β mediates muscle weakness associated with bone metastases in mice.

Cancer-associated muscle weakness is a poorly understood phenomenon, and there is no effective treatment. Here we find that seven different mouse models of human osteolytic bone metastases-representing breast, lung and prostate cancers, as well as multiple myeloma-exhibited impaired muscle function, implicating a role for the tumor-bone microenvironment in cancer-associated muscle weakness. We found that transforming growth factor (TGF)-β, released from the bone surface as a result of metastasis-induced bone destruction, upregulated NADPH oxidase 4 (Nox4), resulting in elevated oxidization of skeletal muscle proteins, including the ryanodine receptor and calcium (Ca(2+)) release channel (RyR1).

TGFβ-Mediated induction of SphK1 as a potential determinant in human MDA-MB-231 breast cancer cell bone metastasis.

Mechanistic understanding of the preferential homing of circulating tumor cells to bone and their perturbation on bone metabolism within the tumor-bone microenvironment remains poorly understood. Alteration in both transforming growth factor β (TGFβ) signaling and sphingolipid metabolism results in the promotion of tumor growth and metastasis. Previous studies using MDA-MB-231 human breast cancer-derived cell lines of variable metastatic potential were queried for changes in sphingolipid metabolism genes to explore correlations between TGFβ dependence and bone metastatic behavior.

The TGF-β Signaling Regulator PMEPA1 Suppresses Prostate Cancer Metastases to Bone.

Transforming growth factor-β (TGF-β) regulates the expression of genes supporting breast cancer cells in bone, but little is known about prostate cancer bone metastases and TGF-β. Our study reveals that the TGFBR1 inhibitor SD208 effectively reduces prostate cancer bone metastases. TGF-β upregulates in prostate cancer cells a set of genes associated with cancer aggressiveness and bone metastases, and the most upregulated gene was PMEPA1.

Tumor-expressed adrenomedullin accelerates breast cancer bone metastasis.

Introduction: Adrenomedullin (AM) is secreted by breast cancer cells and increased by hypoxia. It is a multifunctional peptide that stimulates angiogenesis and proliferation. The peptide is also a potent paracrine stimulator of osteoblasts and bone formation, suggesting a role in skeletal metastases-a major site of treatment-refractory tumor growth in patients with advanced disease.

Halofuginone inhibits the establishment and progression of melanoma bone metastases.

TGF-β derived from bone fuels melanoma bone metastases by inducing tumor secretion of prometastatic factors that act on bone cells to change the skeletal microenvironment. Halofuginone is a plant alkaloid derivative that blocks TGF-β signaling with antiangiogenic and antiproliferative properties. Here, we show for the first time that halofuginone therapy decreases development and progression of bone metastasis caused by melanoma cells through the inhibition of TGF-β signaling.

Regulation of postnatal trabecular bone formation by the osteoblast endothelin A receptor.

Endothelin-1 (ET-1) is a potent vasoconstrictor that also stimulates cells in the osteoblast lineage by binding to the endothelin A receptor (ETAR). ET-1 ligand is widely secreted, particularly by the vasculature. However, the contributions of ETAR signaling to adult bone homeostasis have not been defined.

TGF-beta-RI kinase inhibitor SD-208 reduces the development and progression of melanoma bone metastases.

Melanoma often metastasizes to bone where it is exposed to high concentrations of TGF-β. Constitutive Smad signaling occurs in human melanoma. Because TGF-β promotes metastases to bone by several types of solid tumors including breast cancer, we hypothesized that pharmacologic blockade of the TGF-β signaling pathway may interfere with the capacity of melanoma cells to metastasize to bone.

Hypoxia and TGF-beta drive breast cancer bone metastases through parallel signaling pathways in tumor cells and the bone microenvironment.

Background: Most patients with advanced breast cancer develop bone metastases, which cause pain, hypercalcemia, fractures, nerve compression and paralysis. Chemotherapy causes further bone loss, and bone-specific treatments are only palliative. Multiple tumor-secreted factors act on the bone microenvironment to drive a feed-forward cycle of tumor growth.

Pharmacologic inhibition of the TGF-beta type I receptor kinase has anabolic and anti-catabolic effects on bone.

During development, growth factors and hormones cooperate to establish the unique sizes, shapes and material properties of individual bones. Among these, TGF-beta has been shown to developmentally regulate bone mass and bone matrix properties. However, the mechanisms that control postnatal skeletal integrity in a dynamic biological and mechanical environment are distinct from those that regulate bone development.

Stable overexpression of Smad7 in human melanoma cells impairs bone metastasis.

Melanoma has a propensity to metastasize to bone, where it is exposed to high concentrations of transforming growth factor-beta (TGF-beta). Because TGF-beta promotes bone metastases from other solid tumors, such as breast cancer, we tested the role of TGF-beta in melanoma metastases to bone. 1205Lu melanoma cells, stably transfected to overexpress the natural TGF-beta/Smad signaling inhibitor Smad7, were studied in an experimental model of bone metastasis whereby tumor cells are inoculated into the left cardiac ventricle of nude mice.

Anti-alpha4 integrin antibody suppresses the development of multiple myeloma and associated osteoclastic osteolysis.

Supporting roles of stromal cells in preferential colonization of myeloma cells in bone marrow and development of associated osteoclastic osteolysis through cell-cell interactions have been indicated. Here we examined the effects of a monoclonal antibody to alpha4 integrin (anti-alpha4 Ab) that disrupts myeloma cell-stromal cell interactions mediated via alpha4beta1 integrin and vascular cell adhesion molecule-1 (VCAM-1) on myeloma cell growth in bone marrow and accompanying osteolysis. The anti-alpha4 Ab decreased VCAM-1-stimulated 5TGM1/luc cell growth in culture.

The effect of the bisphosphonate ibandronate on breast cancer metastasis to visceral organs.

Bisphosphonate (BPs), specific inhibitors of osteoclastic bone resorption, are widely used therapeutic agents for bone metastases in breast cancer patients. Nevertheless, the effects of BPs on visceral metastases are controversial. Here we specifically studied the effects of the BP ibandronate on visceral metastases of breast cancer using two animal models.

Tumor-derived platelet-derived growth factor-BB plays a critical role in osteosclerotic bone metastasis in an animal model of human breast cancer.

Breast cancer produces a variety of growth factors to promote its behavior at primary and secondary sites in autocrine/paracrine manners. However, the role of these growth factors in the colonization of cancer cells in bone, which is one of the most common metastatic sites, is poorly understood. To study this, we established an in vivo model in which the MCF-7 human breast cancer cells caused predominant osteosclerotic bone metastases 20-25 weeks after inoculation into the left cardiac ventricle in female nude mice.

A bone-seeking clone exhibits different biological properties from the MDA-MB-231 parental human breast cancer cells and a brain-seeking clone in vivo and in vitro.

Breast cancer has a predilection for spreading to bone. The mechanism of preferential metastasis of breast cancer to bone is unknown. We hypothesize that breast cancer cells that develop bone metastases have the capacity to facilitate their colonization in bone.

Cell-cell contact between marrow stromal cells and myeloma cells via VCAM-1 and alpha(4)beta(1)-integrin enhances production of osteoclast-stimulating activity.

Myeloma is a unique hematologic malignancy that exclusively homes in the bone marrow and induces massive osteoclastic bone destruction presumably by producing cytokines that promote the differentiation of the hematopoietic progenitors to osteoclasts (osteoclastogenesis). It is recognized that neighboring bone marrow stromal cells influence the expression of the malignant phenotype in myeloma cells. This study examined the role of the interactions between myeloma cells and neighboring stromal cells in the production of osteoclastogenic factors to elucidate the mechanism underlying extensive osteoclastic bone destruction.

Actions of bisphosphonate on bone metastasis in animal models of breast carcinoma.

Background: Bone, which abundantly stores a variety of growth factors, provides a fertile soil for cancer cells to develop metastases by supplying these growth factors as a consequence of osteoclastic bone resorption. Accordingly, suppression of osteoclast activity is a primary approach to inhibit bone metastasis, and bisphosphonate (BP), a specific inhibitor of osteoclasts, has been widely used for the treatment of bone metastases in cancer patients. To obtain further insights into the therapeutic usefulness of BP, the authors studied the effects of BP on bone and visceral metastases in animal models of metastasis.

Use of bisphosphonates for the treatment of bone metastasis in experimental animal models.

Therapeutic effectiveness of bisphosphonates (BP) on bone metastases in patients with cancers including those of the breast and prostate has been well documented. However, there are still many important questions that remain unsolved or controversial. To obtain answers for these questions that are not readily addressed in a well-controlled manner in clinical studies, we have developed two animal models of bone metastasis (orthotopic and experimental).

Cadherin-6 mediates the heterotypic interactions between the hemopoietic osteoclast cell lineage and stromal cells in a murine model of osteoclast differentiation.

Osteoclasts are multinucleated cells of hemopoietic origin that are responsible for bone resorption during physiological bone remodeling and in a variety of bone diseases. Osteoclast development requires direct heterotypic cell-cell interactions of the hemopoietic osteoclast precursors with the neighboring osteoblast/stromal cells. However, the molecular mechanisms underlying these heterotypic interactions are poorly understood.

Herbimycin A, a tyrosine kinase inhibitor, impairs hypercalcemia associated with a human squamous cancer producing interleukin-6 in nude mice.

Interleukin-6 (IL-6) is a multifunctional cytokine that is produced not only by a variety of normal cells but also by cancer cells. IL-6 produced by cancer cells stimulates the proliferation of these cancer cells in an autocrine/ paracrine manner and causes paraneoplastic syndromes including hypercalcemia, cachexia, and leukocytosis. We have reported previously that a human oral squamous cancer associated with hypercalcemia produces large amounts of IL-6, that animals bearing this cancer exhibit elevated levels of plasma IL-6, and that neutralizing antibodies to human IL-6 reverse hypercalcemia in tumor-bearing animals, indicating an important role of IL-6 in the hypercalcemia in this model.

pp60 c-src expression and activity in MG-63 osteoblastic cells modulated by PTH but not required for PTH-mediated adenylate cyclase response.

A role for pp60c-src) tyrosine kinase in bone resorption was recently demonstrated in vivo. However, it is not known whether expression of this ubiquitous tyrosine kinase is essential in osteoblasts or osteoclasts. In this work, we have examined the expression of c-src in osteoblast-like cells.

Hormonal regulation of pp60c-src expression during osteoclast formation in vitro.

Recent studies have shown that the protooncogene c-src is required for normal osteoclastic bone resorption. In this study we examined the expression and regulation of pp60c-src in murine bone marrow cultures in which bone-resorbing multinucleated osteoclasts form over 6 days of culture. We found that both pp60c-src protein expression and pp60c-src tyrosine kinase activity correlated closely with the numbers of active osteoclasts in the cultures.

Herbimycin A, a pp60c-src tyrosine kinase inhibitor, inhibits osteoclastic bone resorption in vitro and hypercalcemia in vivo.

Since absence of expression of the c-src gene product in mice indicates that the pp60c-src tyrosine kinase is required and essential for osteoclastic bone resorption, we tested the effects of the antibiotic herbimycin A, which is an inhibitor of pp60c-src on osteoclastic bone resorption in vitro and on hypercalcemia in vivo. We examined the effects of herbimycin A on the formation of bone resorbing osteoclasts in mouse long-term marrow cultures, on isolated rodent osteoclasts and on bone resorption in organ cultures of fetal rat long bones stimulated by parathyroid hormone. We found that herbimycin A in concentrations of 1-100 ng/ml inhibited bone resorption in each of these systems.

[Analysis of the prognostic significance of serum immunoglobulins in Hodgkin's disease].

Main classes of serum immunoglobulins have been studied in plasma of patients with untreated Hodgkin's disease and correlations have been analyzed between their levels and the clinical stage of the disease, its histological type and the patient's age and survival. In the Hematology Department, Wrocław, in the years 1979-1989 to the study 115 cases were qualified, 59 were female, 56 male, 75 are still under treatment, whereas 40 died. Stage III B and IV B and histological type NS and MC prevailed.