Publications by authors named "John M Chirgwin"

Purpose Of Review: To describe the contributions of osteocytes to the lesions in Paget's disease, which are characterized by locally overactive bone resorption and formation.

Recent Findings: Osteocytes, the most abundant cells in bone, are altered in Paget's disease lesions, displaying increased size, decreased canalicular length, incomplete differentiation, and less sclerostin expression compared to controls in both patients and mouse models. Pagetic lesions show increased senescent osteocytes that express RANK ligand, which drives osteoclastic bone resorption.

View Article and Find Full Text PDF

Multiple myeloma (MM) is a malignancy of plasma cells whose antibody secretion creates proteotoxic stress relieved by the N-end rule pathway, a proteolytic system that degrades N-arginylated proteins in the proteasome. When the proteasome is inhibited, protein cargo is alternatively targeted for autophagic degradation by binding to the ZZ-domain of p62/ sequestosome-1. Here, we demonstrate that XRK3F2, a selective ligand for the ZZ-domain, dramatically improved two major responses to the proteasome inhibitor bortezomib (Btz) by increasing: i) killing of human MM cells by stimulating both Btz-mediated apoptosis and necroptosis, a process regulated by p62; and ii) preservation of bone mass by stimulating osteoblast differentiation and inhibiting osteoclastic bone destruction.

View Article and Find Full Text PDF

We previously reported that measles virus nucleocapsid protein (MVNP) expression in osteoclasts (OCLs) of patients with Paget disease (PD) or targeted to the OCL lineage in MVNP-transgenic mice (MVNP mice) increases IGF1 production in osteoclasts (OCL-IGF1) and leads to development of PD OCLs and pagetic bone lesions (PDLs). Conditional deletion of Igf1 in OCLs of MVNP mice fully blocked development of PDLs. In this study, we examined whether osteocytes (OCys), key regulators of normal bone remodeling, contribute to PD.

View Article and Find Full Text PDF

We report that transgenic mice expressing measles virus nucleocapsid protein (MVNP) in osteoclasts (OCLs) (MVNP mice) are Paget's disease (PD) models and that OCLs from patients with PD and MVNP mice express high levels of OCL-derived IGF1 (OCL-IGF1). To determine OCL-IGF1's role in PD and normal bone remodeling, we generated WT and MVNP mice with targeted deletion of Igf1 in OCLs (Igf1-cKO) and MVNP/Igf1-cKO mice, and we assessed OCL-IGF1's effects on bone mass, bone formation rate, EphB2/EphB4 expression on OCLs and osteoblasts (OBs), and pagetic bone lesions (PDLs). A total of 40% of MVNP mice, but no MVNP/Igf1-cKO mice, had PDLs.

View Article and Find Full Text PDF

Bone is a common site of metastasis for breast, prostate, lung, kidney and other cancers. Bone metastases are incurable, and substantially reduce patient quality of life. To date, there exists no small-molecule therapeutic agent that can reduce tumor burden in bone.

View Article and Find Full Text PDF

Semaphorin 4D (Sema4D; CD100) is a transmembrane homodimer 150-kDa glycoprotein member of the Semaphorin family. Semaphorins were first identified as chemorepellants that guide neural axon growth. Sema4D also possesses immune regulatory activity.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

In multiple myeloma, an overabundance of monoclonal plasma cells in the bone marrow induces localized osteolytic lesions that rarely heal due to increased bone resorption and suppressed bone formation. Matrix-embedded osteocytes comprise more than 95% of bone cells and are major regulators of osteoclast and osteoblast activity, but their contribution to multiple myeloma growth and bone disease is unknown. Here, we report that osteocytes in a mouse model of human MM physically interact with multiple myeloma cells in vivo, undergo caspase-3-dependent apoptosis, and express higher RANKL (TNFSF11) and sclerostin levels than osteocytes in control mice.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

Multiply myeloma (MM) grows in and destroys bone, where osteocytes secrete FGF23, a hormone which affects phosphate homeostasis and aging. We report that multiple myeloma (MM) cells express receptors for and respond to FGF23. FGF23 increased mRNA for EGR1 and its target heparanase, a pro-osteolytic factor in MM.

View Article and Find Full Text PDF
Article Synopsis
  • Skeletal metastases, which are common in advanced breast cancer, lead to serious issues like pain and fractures, significantly affecting patients' quality of life, with many experiencing several years of illness after diagnosis.
  • Current treatments mainly aim to relieve symptoms by targeting bone-destroying cells and are mostly palliative, but recent studies indicate potential benefits from medications like everolimus and selective estrogen receptor modulators that may also enhance bone formation.
  • Future approaches may focus on using bone-building (anabolic) agents in conjunction with anti-tumor treatments, with some existing drugs showing potential for both promoting bone health and inhibiting the growth of breast cancer metastases.
View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF
Article Synopsis
  • Advanced cancers like prostate and breast can spread to the bones, making them very hard to treat and causing serious health problems.
  • Tumors can take a long time to grow in the bones, which gives us a chance to find ways to stop this from happening.
  • Researchers are looking for new medicines that can help the body’s normal cells fight against cancer cells in the bones, which may help prevent the cancer from spreading.
View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

Bone is the most common site for metastasis of advanced prostate cancers. Once housed in the skeleton, tumors are incurable and cause protracted morbidity, and bone metastases may contribute to mortality through unknown mechanisms. Bone provides a unique microenvironment whose local interactions with tumor cells offer novel targets for therapeutic interventions.

View Article and Find Full Text PDF

Bone formation is a complex process, and testing anabolic effects on the skeleton of agents is slow and expensive in animals. Neonatal mouse calvariae cultured ex vivo show strong anabolic or catabolic bone responses to 1-week treatments and can be analyzed by quantitative histomorphometry. Changes in new bone area and osteoblast number caused by added proteins, drugs, or transfected genes can be quantified and analyzed for statistical significance.

View Article and Find Full Text PDF
Article Synopsis
  • Adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) are secretory hormones that can also be found inside cells, interacting with microtubule-associated proteins (MAPs) and tubulin.
  • The study utilized yeast-2 hybrid technology and fluorescent tagging to demonstrate that AM and PAMP decorate microtubules and colocalize with other MAPs, with PAMP specifically destabilizing tubulin polymerization.
  • Down-regulating AM and PAMP genes led to stabilized microtubules, increased posttranslational modifications of tubulin, reduced cell motility, and a partial halt in the G2 phase of the cell cycle, indicating PAMP acts
View Article and Find Full Text PDF

Metastasis is a final stage of tumor progression. Breast and prostate cancer cells preferentially metastasize to bone, wherein they cause incurable osteolytic and osteoblastic lesions. The bone matrix is rich in factors, such as transforming growth factor-beta and insulin-like growth factors, which are released into the tumor microenvironment by osteolysis.

View Article and Find Full Text PDF
Article Synopsis
  • Advanced cancers often spread to bones, creating incurable and painful bone metastases that result from a damaging cycle of tumor and bone cell interactions.
  • Tumors release substances that stimulate bone cells, which then produce factors that further promote tumor growth, creating a self-sustaining feedback loop.
  • New treatment strategies focus on disrupting this cycle by targeting bone cells or inhibiting tumor responses to local factors, showing promise in animal studies with combination therapies reducing tumor size effectively.
View Article and Find Full Text PDF

Tumor-produced endothelin-1 (ET-1) stimulates osteoblasts to form new bone and is an important mediator of osteoblastic bone metastasis. The anabolic actions of ET-1 in osteoblasts were investigated by gene microarray analyses of murine neonatal calvarial organ cultures. Targets of ET-1 action were validated by real-time RT-PCR in murine primary osteoblast cultures.

View Article and Find Full Text PDF

Certain solid tumors metastasize to bone and cause osteolysis and abnormal new bone formation. The respective phenotypes of dysregulated bone destruction and bone formation represent two ends of a spectrum, and most patients will have evidence of both. The mechanisms responsible for tumor growth in bone are complex and involve tumor stimulation of the osteoclast and the osteoblast as well as the response of the bone microenvironment.

View Article and Find Full Text PDF
Article Synopsis
  • Bone metastases influence the bone environment, where cancer cells interact with osteoblasts and osteoclasts, affecting new bone formation and resorption, which in turn stimulates tumor growth.
  • Recent studies show that bone metastatic cancer cells release factors that recruit and activate T cells, which can contribute to bone remodeling and may enhance bone resorption, affecting immune responses.
  • T cells in bone metastases might be suppressed by the surrounding environment, leading to increased bone resorption and creating favorable conditions for tumor growth instead of attacking cancer cells.
View Article and Find Full Text PDF