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1.
Int J Mol Sci ; 22(11)2021 May 25.
Article in English | MEDLINE | ID: mdl-34070363

ABSTRACT

Osteolytic bone disease is a hallmark of multiple myeloma (MM) mediated by MM cell proliferation, increased osteoclast activity, and suppressed osteoblast function. The proteasome inhibitor bortezomib targets MM cells and improves bone health in MM patients. Radium-223 dichloride (radium-223), the first targeted alpha therapy approved, specifically targets bone metastases, where it disrupts the activity of both tumor cells and tumor-supporting bone cells in mouse models of breast and prostate cancer bone metastasis. We hypothesized that radium-223 and bortezomib combination treatment would have additive effects on MM. In vitro experiments revealed that the combination treatment inhibited MM cell proliferation and demonstrated additive efficacy. In the systemic, syngeneic 5TGM1 mouse MM model, both bortezomib and radium-223 decreased the osteolytic lesion area, and their combination was more effective than either monotherapy alone. Bortezomib decreased the number of osteoclasts at the tumor-bone interface, and the combination therapy resulted in almost complete eradication of osteoclasts. Furthermore, the combination therapy improved the incorporation of radium-223 into MM-bearing bone. Importantly, the combination therapy decreased tumor burden and restored body weights in MM mice. These results suggest that the combination of radium-223 with bortezomib could constitute a novel, effective therapy for MM and, in particular, myeloma bone disease.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Multiple Myeloma , Neoplasms, Experimental , Animals , Bortezomib/pharmacology , Cell Line, Tumor , Humans , Mice , Multiple Myeloma/drug therapy , Multiple Myeloma/metabolism , Multiple Myeloma/pathology , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Radioisotopes/pharmacology , Radium/pharmacology
2.
Clin Cancer Res ; 23(15): 4335-4346, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28364014

ABSTRACT

Purpose: Radium-223 dichloride (radium-223, Xofigo), a targeted alpha therapy, is currently used for the treatment of patients with castration-resistant prostate cancer (CRPC) with bone metastases. This study examines the mode-of-action and antitumor efficacy of radium-223 in two prostate cancer xenograft models.Experimental Design: Mice bearing intratibial LNCaP or LuCaP 58 tumors were randomized into groups (n = 12-17) based on lesion grade and/or serum PSA level and administered radium-223 (300 kBq/kg) or vehicle, twice at 4-week intervals. X-rays and serum samples were obtained biweekly. Soft tissue tumors were observed macroscopically at sacrifice. Tibiae were analyzed by gamma counter, micro-CT, autoradiography and histology.Results: Radium-223 inhibited tumor-induced osteoblastic bone growth and protected normal bone architecture, leading to reduced bone volume in LNCaP and abiraterone-resistant LuCaP 58 models. Furthermore, radium-223 resulted in lower PSA values and reduced total tissue and tumor areas, indicating that treatment constrains prostate cancer growth in bone. In addition, radium-223 suppressed abnormal bone metabolic activity as evidenced by decreased number of osteoblasts and osteoclasts and reduced level of the bone formation marker PINP. Mode-of-action studies revealed that radium-223 was deposited in the intratumoral bone matrix. DNA double-strand breaks were induced in cancer cells within 24 hours after radium-223 treatment, and PSA levels were significantly lower 72 hours after treatment, providing further evidence of the antitumor effects.Conclusions: Taken together, radium-223 therapy exhibits a dual targeting mode-of-action that induces tumor cell death and suppresses tumor-induced pathologic bone formation in tumor microenvironment of osseous CRPC growth in mice. Clin Cancer Res; 23(15); 4335-46. ©2017 AACR.


Subject(s)
Antineoplastic Agents/administration & dosage , Bone Neoplasms/radiotherapy , Prostatic Neoplasms, Castration-Resistant/radiotherapy , Radium/administration & dosage , Animals , Bone Neoplasms/pathology , Bone Neoplasms/secondary , Bone and Bones/pathology , Bone and Bones/radiation effects , Cell Line, Tumor , Cell Proliferation/radiation effects , Disease Models, Animal , Humans , Male , Mice , Osteoclasts/radiation effects , Prostatic Neoplasms, Castration-Resistant/pathology , Radioisotopes/administration & dosage , Tumor Microenvironment/radiation effects
3.
Sci Rep ; 6: 22585, 2016 Mar 03.
Article in English | MEDLINE | ID: mdl-26935172

ABSTRACT

To elucidate processes in the osteoclastic bone resorption, visualise resorption and related actin reorganisation, a combination of imaging technologies and an applicable in vitro model is needed. Nanosized bone powder from matching species is deposited on any biocompatible surface in order to form a thin, translucent, smooth and elastic representation of injured bone. Osteoclasts cultured on the layer expressed matching morphology to ones cultured on sawed cortical bone slices. Resorption pits were easily identified by reflectance microscopy. The coating allowed actin structures on the bone interface to be visualised with super-resolution microscopy along with a detailed interlinked actin networks and actin branching in conjunction with V-ATPase, dynamin and Arp2/3 at actin patches. Furthermore, we measured the timescale of an adaptive osteoclast adhesion to bone by force spectroscopy experiments on live osteoclasts with bone-coated AFM cantilevers. Utilising the in vitro model and the advanced imaging technologies we localised immunofluorescence signals in respect to bone with high precision and detected resorption at its early stages. Put together, our data supports a cyclic model for resorption in human osteoclasts.


Subject(s)
Bone Resorption/metabolism , Models, Biological , Osteoclasts/metabolism , Bone Resorption/pathology , Female , Humans , Male , Microscopy, Atomic Force , Microscopy, Interference , Osteoclasts/ultrastructure
4.
J Natl Cancer Inst ; 105(12): 908-16, 2013 Jun 19.
Article in English | MEDLINE | ID: mdl-23682134

ABSTRACT

BACKGROUND: Bone metastases are associated with increased morbidity and poor prognosis in breast cancer patients. Radium-223 dichloride is a calcium mimetic that localizes to bone, providing targeted therapy for skeletal metastasis. METHODS: We investigated the mode of action of radium-223 dichloride using breast cancer cell, osteoclast, and osteoblast cultures as well as a mouse model of breast cancer bone metastasis. A single dose of radium-223 dichloride was used in three different settings mimicking the prevention or treatment of bone metastasis. Disease progression was monitored using fluorescence and radiographic imaging and histological analyses. The effect of radium-223 dichloride alone and in combination with doxorubicin or zoledronic acid on survival of mice was analyzed by Kaplan-Meier methods. All statistical tests used were two-sided. RESULTS: Radium-223 dichloride incorporated into bone matrix and inhibited proliferation of breast cancer cells and differentiation of osteoblasts and osteoclasts (all P values < .001) in vitro. In an established bone metastasis setting, radium-223 dichloride prevented tumor-induced cachexia (0/14 vs 7/14 control mice) and decreased osteolysis by 56% and tumor growth by 43% (all P values < .05). Radium-223 dichloride induced double-strand DNA breaks in cancer cells in vivo. Finally, radium-223 dichloride extended survival as a monotherapy (29.2 days, 95% confidence interval [CI] = 26.6 to 31.8 days, P = .039) and in combination with zoledronic acid (31.4 days, 95% CI = 28.8 to 34.0 days, P = .004) or doxorubicin (31.5 days, 95% CI = 29.5 to 33.5 days, P < .001) compared to the vehicle group (24.9 days, 95% CI = 23.4 to 26.4 days). Similar but even more pronounced effects were observed when radium-223 dichloride was administered in a preventive or micrometastatic setting. CONCLUSIONS: Our findings strongly support the development of radium-223 dichloride for the treatment of breast cancer patients with or at high risk of developing bone metastases.


Subject(s)
Antineoplastic Agents/pharmacology , Bone Neoplasms/drug therapy , Bone Neoplasms/secondary , Breast Neoplasms/pathology , Cachexia/prevention & control , DNA, Neoplasm/drug effects , Radium/pharmacology , Animals , Antineoplastic Agents/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Bone Density Conservation Agents/administration & dosage , Bone Neoplasms/complications , Bone Neoplasms/metabolism , Bone Neoplasms/prevention & control , Cachexia/diagnosis , Cachexia/etiology , Cell Proliferation/drug effects , DNA Breaks, Double-Stranded/drug effects , Diphosphonates/administration & dosage , Disease Models, Animal , Doxorubicin/administration & dosage , Female , Imidazoles/administration & dosage , Kaplan-Meier Estimate , Mice , Osteoblasts/drug effects , Osteoclasts/drug effects , Radioisotopes/pharmacology , Radioisotopes/therapeutic use , Radium/therapeutic use , Stem Cells/drug effects , Tumor Cells, Cultured , Zoledronic Acid
5.
Clin Lab ; 55(5-6): 223-8, 2009.
Article in English | MEDLINE | ID: mdl-19728556

ABSTRACT

Two forms of tartrate-resistant acid phosphatase (TRACP) circulate in human blood, TRACP 5a derived from inflammatory macrophages and TRACP 5b derived from osteoclasts. Serum TRACP 5b is a clinically useful marker of osteoclast number and bone resorption. We have studied TRACP 5b specificity of two commercially available immunoassays that are stated to be TRACP 5b specific, the BoneTRAP assay and the MetraTRAP5b assay, and investigated their clinical performance for monitoring the efficacy of alendronate treatment. Both assays bound TRACP 5b equally and had similar cross-reactivity to TRACP 5a. The mean decrease in the alendronate group was higher with the MetraTRAP5b assay, but the clinical performance of the two assays for monitoring alendronate treatment was equal due to higher variability of the MetraTRAP5b assay. We conclude that the BoneTRAP assay and the MetraTRAP5b assay have similar specificity for TRACP 5b, and similar clinical performance for monitoring alendronate treatment.


Subject(s)
Acid Phosphatase/blood , Isoenzymes/blood , Bone and Bones/enzymology , Humans , Immunoassay/methods , Macrophages/enzymology , Sensitivity and Specificity , Substrate Specificity , Tartrate-Resistant Acid Phosphatase
6.
J Bone Miner Metab ; 27(1): 105-9, 2009.
Article in English | MEDLINE | ID: mdl-19018457

ABSTRACT

We cultured human bone marrow-derived stem cells on bovine bone slices in 96-well plates in the presence of M-CSF and RANKL, allowing them to differentiate into osteoclasts. Secreted TRACP 5b was a useful endpoint measurement to demonstrate effects of inhibitors of osteoclast differentiation in the culture system, reflecting accurately the number of formed osteoclasts. Inhibitors of osteoclast activity were added into the cultures after the differentiation period, and the cultures were continued to allow the formed osteoclasts to resorb bone. CTX values obtained after the resorption period were normalized with TRACP 5b values obtained after the differentiation period, before adding the inhibitors. This normalization prevents false results that could be obtained from the presence of different amounts of osteoclasts in different wells before adding the inhibitors. These results demonstrate that the use of TRACP 5b and CTX allows rapid and reliable testing of antiresorptive compounds in human osteoclast cultures.


Subject(s)
Bone Density Conservation Agents/pharmacology , Osteoclasts/drug effects , Acid Phosphatase/metabolism , Animals , Bone Density Conservation Agents/therapeutic use , Bone Resorption/drug therapy , Bone Resorption/physiopathology , Cattle , Cells, Cultured , Collagen Type I/metabolism , Humans , Isoenzymes/metabolism , Osteoclasts/cytology , Osteoclasts/metabolism , Tartrate-Resistant Acid Phosphatase
7.
Clin Lab ; 54(9-10): 347-54, 2008.
Article in English | MEDLINE | ID: mdl-19097492

ABSTRACT

Two forms of tartrate-resistant acid phosphatase (TRACP) circulate in human blood, TRACP 5a derived from inflammatory macrophages and TRACP 5b derived from osteoclasts. We compared the clinical performance of the following TRACP immunoassays for monitoring alendronate treatment in postmenopausal women: 1) TRACP 5b activity using a selective pH; 2) TRACP 5b activity using a selective substrate; 3) Total TRACP activity; 4) Total TRACP protein amount; 5) TRACP 5a activity; 6) TRACP 5a protein amount. TRACP and other bone turnover markers were measured before the start of treatment and at 3 months. Alendronate treatment decreased TRACP values determined with assays 1, 2 and 3, and had no effect on the values determined with assays 4, 5 and 6. Clinical performance of assays 1, 2 and 3 was good, and these assays correlated with each other and with the other bone markers. This study showed that TRACP 5b specific methods are useful for monitoring changes in bone resorption during alendronate treatment, and alendronate treatment does not affect serum TRACP 5a levels.


Subject(s)
Acid Phosphatase/blood , Alendronate/therapeutic use , Bone Density Conservation Agents/therapeutic use , Drug Monitoring/methods , Immunoenzyme Techniques/methods , Isoenzymes/blood , Female , Humans , Postmenopause , ROC Curve , Randomized Controlled Trials as Topic , Tartrate-Resistant Acid Phosphatase
8.
Clin Lab ; 52(9-10): 499-509, 2006.
Article in English | MEDLINE | ID: mdl-17078477

ABSTRACT

Tartrate-resistant acid phosphatase (TRACP) is an enzyme that is expressed in high amounts by bone resorbing osteoclasts, inflammatory macrophages and dendritic cells. Two forms of TRACP circulate in human blood, TRACP 5a derived from macrophages and dendritic cells, and TRACP 5b derived from osteoclasts. Recent data have demonstrated the utility of TRACP 5b as a marker of osteoclast number and bone resorption, and serum TRACP 5a as a marker of inflammatory conditions. This review summarizes the scientific knowledge on the role of TRACP in osteoclastic bone resorption, the mechanism of TRACP 5b generation in osteoclasts and its secretion into the blood circulation, the methodology of measuring TRACP 5b, diagnostic evidence for the use of TRACP 5b as a resorption marker, and characteristics of TRACP 5b compared to other commonly used bone turnover markers.


Subject(s)
Acid Phosphatase/blood , Acid Phosphatase/metabolism , Bone Resorption/diagnosis , Immunoassay/methods , Isoenzymes/blood , Isoenzymes/metabolism , Biomarkers/blood , Biomarkers/metabolism , Bone Resorption/metabolism , Bone Resorption/therapy , Cell Count , Enzyme Stability , Humans , Monitoring, Physiologic , Osteoclasts/enzymology , Protein Isoforms/blood , Protein Isoforms/metabolism , Tartrate-Resistant Acid Phosphatase
9.
Arch Biochem Biophys ; 449(1-2): 1-7, 2006 May 15.
Article in English | MEDLINE | ID: mdl-16620768

ABSTRACT

Osteoclasts and macrophages express high amounts of tartrate-resistant acid phosphatase (TRACP), an enzyme with unknown biological function. TRACP contains a disulfide bond, a protease-sensitive loop peptide, and a redox-active iron that can catalyze formation of reactive oxygen species (ROS). We studied the effects of proteolytic cleavage by trypsin, reduction of the disulfide bond by beta-mercaptoethanol, and reduction of the redox-active iron by ascorbate on the phosphatase and ROS-generating activity of baculovirus-generated recombinant human TRACP. Ascorbate alone and trypsin in combination with beta-mercaptoethanol increased k(cat)/K(m) of the phosphatase activity seven- to ninefold. The pH-optimum was changed from 5.4-5.6 to 6.2-6.4 by ascorbate and trypsin cleavage. Trypsin cleavage increased k(cat)/K(m) of the ROS-generating activity 2.5-fold without affecting the pH-optimum (7.0). These results suggest that the protease-sensitive loop peptide, redox-active iron, and disulfide bond are important regulatory sites in TRACP, and that the phosphatase and ROS-generating activity are performed with different reaction mechanisms.


Subject(s)
Acid Phosphatase/chemistry , Isoenzymes/chemistry , Peptide Hydrolases/chemistry , Phosphoric Monoester Hydrolases/metabolism , Reactive Oxygen Species/chemistry , Enzyme Activation , Humans , Hydrogen-Ion Concentration , Oxidation-Reduction , Protein Binding , Recombinant Proteins/metabolism , Tartrate-Resistant Acid Phosphatase
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