Cancer Bone Metastasis Research Articles

LINC01128 regulates the development of osteosarcoma by sponging miR-299-3p to mediate MMP2 expression and activating Wnt/β-catenin signalling pathway.

Osteosarcoma (OS) is one of the most common metastatic bone cancers, which results in significant morbidity and mortality. The important role of long non‐coding RNAs (lncRNAs) in the biological processes of OS has been demonstrated through several studies. In the current study, we evaluated the role of the lncRNA, LINC01128, in OS. We analysed the expression of LINC01128 in three OS gene expression omnibus (GEO) data sets GSE21257, GSE36001 and GSE42352. The expression of LINC01128 in OS tissues and matched non‐tumour tissues obtained from 50 OS patients was detected using qRT‐PCR. The association between LINC01128 expression and overall survival of OS patients was evaluated using the Kaplan‐Meier method. The effects of LINC01128 knockdown and overexpression were evaluated through in vitro and in vivo assays. The LINC01128/miR‐299‐3p/ MMP2 axis was verified using dual‐luciferase reporter assay and qRT‐PCR assays. GEO data sets analysis revealed that the expression of LINC01128 was increased in OS. Elevated LINC01128 expression was accompanied by shorter overall survival in OS patients. Functional studies revealed that LINC01128 knockdown reduced the proliferation, migration and invasion of OS cells both in vitro and in vivo. Mechanistically, LINC01128 sponged miR‐299‐3p to increase MMP2 expression. Rescue assays determined the role of the LINC01128/miR‐299‐3p/MMP2 axis in the proliferation, migration and invasion of OS cells. Additionally, the Wnt/β‐catenin signalling pathway was activated by LINC01128 and MMP2 in OS cell lines. In summary, this study demonstrates that LINC01128 facilitates OS by functioning as a sponge of miR‐299‐3p, thus promoting MMP2 expression and activating the Wnt/β‐catenin signalling pathway.

Quantitative bone single photon emission computed tomography analysis of the effects of duration of bisphosphonate administration on the parietal bone

Effects of long-term bisphosphonate (BP) administration on the metabolism of healthy bone and the concomitant changes in imaging are unclear. Hence, we aimed to retrospectively investigate the effects of long-term BP administration on the intact parietal bone using the standardised uptake value (SUV) derived from single photon emission computed tomography (SPECT). We enrolled 29 patients who had odontogenic infection, osteoporosis, bone metastasis cancer, or rheumatoid arthritis, and classified them into BP-naïve: A (14 patients) and BP-treated: B, < 4 years (7 patients) and C, ≥ 4 years (8 patients) groups. We measured the maximum bilateral SUV (SUVmax) of the parietal bone using quantitative bone SPECT software. There were significant differences in the duration of BP administration and SUVmax of the parietal bone among the diseases (P < 0.0001 and P = 0.0086, respectively). There was a positive correlation between the duration of BP administration and SUVmax of the parietal bone (rs = 0.65, P = 0.0002). The SUVmax was significantly different between A and B (P = 0.02) and between A and C (P = 0.0024) groups. This is the first report on the correlation between long-term BP administration and the SUVmax of the parietal bone using the quantitative bone SPECT analysis.

Obesity and Cathepsin K: A Complex Pathophysiological Relationship in Breast Cancer Metastases.

Breast cancer appears in a strong inclination to metastasize in bone tissue. Several strategies are discussed in combating bone metastasis in breast cancer. However, therapy is only palliative and does not provide any improvement in survival to the majority of patients with advanced cancer. Obese and overweight women with breast cancer are three times more likely to develop metastatic disease compared to normal-weight women with the same treatment regimen. Overweight greatly intensify adipocytes formation in the bone marrow affecting bone metabolism by decreasing osteoblast differentiation and bone formation. Cathepsin K (CTSK), a cysteine protease, effectively degrades several components of the extracellular matrix and has the ability to differentiate adipocytes from bone marrow lineage. Therefore, the purpose of this review is to emphasize the underlying mechanism of CTSK and obesity role in breast cancer metastasis. Systematic review was performed using PubMed, EMBASE. The evidence of obesity and CTSK in breast cancer skeletal metastasis were analyzed, summarized and compared. The present investigation argues for a specific association of CTSK with breast cancer skeletal metastasis by promoting adipocyte differentiation. The potential tumor-supporting roles of adipocytes are well documented, and in fact, suppressing adipocyte could be a new therapeutic option in the battle against lethal metastatic breast cancers. This review emphasizes CTSK through its multifaceted role in differentiating adipocytes, inflammation, and extracellular degradation, may be a critical factor in an obesity-cancer connection. Thus, integration of CTSK targeting strategies into established traditional therapies seems to hold substantial promise.

Physiologic osteoclasts are not sufficient to induce skeletal pain in mice.

BackgroundIncreased bone resorption is driven by augmented osteoclast activity in pathological states of the bone, including osteoporosis, fracture and metastatic bone cancer. Pain is a frequent co‐morbidity in bone pathologies and adequate pain management is necessary for symptomatic relief. Bone cancer is associated with severe skeletal pain and dysregulated bone remodelling, while increased osteoclast activity and bone pain are also observed in osteoporosis and during fracture repair. However, the effects of altered osteoclast activity and bone resorption on nociceptive processing of bone afferents remain unclear.MethodsThis study investigates whether physiologic osteoclasts and resulting changes in bone resorption can induce skeletal pain. We first assessed correlation between changes in bone microarchitecture (through µCT) and skeletal pain using standardized behavioural phenotyping assays in a mouse model of metastatic bone cancer. We then investigated whether increased activity of physiologic osteoclasts, and the associated bone resorption, is sufficient to induce skeletal pain using mouse models of localized and widespread bone resorption following administration of exogenous receptor activator of nuclear factor kappa‐B ligand (RANKL).ResultsOur data demonstrates that mice with bone cancer exhibit progressive pain behaviours that correlate with increased bone resorption at the tumour site. Systemic RANKL injections enhance osteoclast activity and associated bone resorption, without producing any changes in motor function or pain behaviours at both early and late timepoints.ConclusionThese findings suggest that activation of homeostatic osteoclasts alone is not sufficient to induce skeletal pain in mice.Significance statementThe role of osteoclasts in peripheral sensitization of sensory neurones is not fully understood. This study reports on the direct link between oestrogen‐independent osteoclast activation and skeletal pain. Administration of exogenous receptor activator of nuclear factor kappa‐B ligand (RANKL) increases bone resorption, but does not produce pro‐nociceptive changes in behavioural pain thresholds. Our data demonstrates that physiologic osteoclasts are not essential for skeletal pain behaviours.

The Role of Cathepsins in the Growth of Primary and Secondary Neoplasia in the Bone

The upregulation of proteolytic enzymes has been demonstrated to promote primary tumor development and metastatic bone cancer. The secreted proteases increase tumor growth and angiogenesis, and potentiate neoplastic cell dissemination. This article reviews the role and mechanisms of cathepsins in normal physiology, cancer, bone remodeling, and the tumor–bone interface, with a specific focus on cathepsins B, D, H, G, L, and K. In this review, we highlight the role of cathepsins in primary bone cancer (i.e., osteosarcoma (OS)), as well as metastatic breast (BCa) and prostate (PCa) cancer. In addition, we discuss the clinical utility and therapeutic potential of cathepsin-targeted treatments in primary and secondary bone cancers.

Longitudinal analysis of complete blood count parameters in advanced-stage lung cancer patients.

BackgroundMetastatic lung cancer is a debilitating disease, but with the advances in immunotherapy, therapeutic options have vastly increased. Numerous complete blood count parameters (CBC) have been described as easily accessible biomarkers that might predict response to immunotherapy. However, to date, no comprehensive study has been performed on the longitudinal changes of these parameters during cancer progression.MethodsThe clinicopathological variables and CBC parameters of 986 advanced stage lung cancer patients were retrospectively analyzed. Blood tests were performed as part of the routine checkup and the results were recorded at the time of the diagnosis of the primary tumor, the diagnosis of brain or bone metastases, and also during the last available follow‐up.ResultsIn the experimental subcohort, 352 and 466 patients were diagnosed with brain and bone metastases, respectively. The control group consisted of 168 patients without clinically detectable or other distant organ metastases. In our longitudinal analyses, we found significantly decreasing absolute lymphocyte count (ALC: P < 0.001), and significantly increasing absolute neutrophil count (ANC: P < 0.001) levels in all patient subgroups, irrespective of histopathological type and metastatic site. Interestingly, patients with brain metastases had significantly descending‐ascending platelet count (PLT) trendlines (P < 0.001), while the bone metastatic subgroup exhibited significantly ascending‐descending trendlines (P = 0.043).ConclusionsSignificantly decreasing ALC, significantly increasing ANC and fluctuating PLT levels may be found in brain and bone metastatic lung cancer patients during disease progression. Our findings might contribute to improve personalized healthcare in this devastating malignancy.Key pointsSignificant findings of the study Significantly decreasing ALC, and significantly increasing ANC levels can be found in advanced‐stage lung cancer patients during disease progressionPatients with brain metastases have descending‐ascending PLT trendlines, while patients with bone metastases exhibit ascending‐descending trendlines during disease progression What this study adds The descending values for ALC, and the ascending mean values for PLT and ANC, might be suggestive of poor response to second‐ or third‐line immunotherapy in advanced‐stage lung cancer patients.The current study might help to improve patient selection and treatment strategies for brain and/or bone metastatic lung cancer patients.

Cellulose nanocrystals: a multimodal tool to enhance the targeted drug delivery against bone disorders.

Aim: We investigated the use of cellulose nanocrystals (CNCs) as drug nanocarriers combining an anti-osteoporotic agent, alendronate (ALN), and an anti-cancer drug, doxorubicin (DOX). Materials & methods: CNC physicochemical characterization, in vivo imaging coupled with histology andin vitro uptake and toxicity assays were carried out. Results:In vivo CNC-ALN did not modify bone tropism and lung penetration, whereas its liver and kidneyaccumulation wasslightly higher compared with CNCs alone. In vitro studies showed that CNC-ALN did not impair ALN's effect on osteoclasts, whereasCNC-DOX confirmed the therapeutic potential against bone metastatic cancer cells. Conclusions: This study provides robust proofof the potential of CNCs as easy, flexible and specific carriers to deliver compounds to the bone.

Systems for local, sustained release of zoledronic acid as a potential treatment for metastatic bone disease.

Bone pain is the leading cause of morbidity in patients with metastatic cancer. Systemic administration of zoledronic acid (ZA) decreases skeletally-related events in bone cancer patients but is associated with major side effects. This project investigated two biomaterials, poly(methyl methacrylate) (PMMA) bone cement and poly(lactic-co-glycolic acid) (PLGA), for local ZA delivery. Compressive properties of PMMA samples were tested with increased drug loading, and in vitro ZA release profiles from PMMA cylinders and PLGA films were measured over 8weeks. The activity of ZA eluted from both materials was evaluated on the RAW 264.7 macrophage cell line. PMMA samples released up to only 17% of incorporated drug, whereas PLGA films released over 95%. A burst profile was observed for PMMA, while ZA release from PLGA exhibited a typical triphasic profile. Drug bioactivity remained above 50% for both materials. Local ZA delivery from these materials may be useful in the treatment of metastatic bone cancer.

Rational Design and Synthesis of Methyl-β-d-galactomalonyl Phenyl Esters as Potent Galectin-8N Antagonists.

Galectin-8 is a β-galactoside-recognizing protein having an important role in the regulation of bone remodeling and cancer progression and metastasis. Methyl β-d-galactopyranoside malonyl aromatic esters have been designed to target and engage with particular amino acid residues of the galectin-8N extended carbohydrate-binding site. The chemically synthesized compounds had in vitro binding affinity toward galectin-8N in the range of 5-33 μM, as evaluated by isothermal titration calorimetry. This affinity directly correlated with the compounds' ability to inhibit galectin-8-induced expression of chemokines and proinflammatory cytokines in the SUM159 breast cancer cell line. X-ray crystallographic structure determination revealed that these monosaccharide-based compounds bind galectin-8N by engaging its unique arginine (Arg59) and simultaneously cross-linking to another arginine (Arg45) located across the carbohydrate-binding site. This structure-based drug design approach has led to the discovery of novel monosaccharide galactose-based antagonists, with the strongest-binding compound (Kd 5.72 μM) holding 7-fold tighter than the disaccharide lactose.

Abstract 693: Effects of a bone-anabolic agent on metastatic bone cancer growth

Abstract Introduction: Cancer cells colonized to bone pathologically alter the bone niche to support the cancers' growth and survival. Multiple myeloma (MM) and metastatic solid tumors, particularly breast cancer (BC), activate osteoclasts and suppress osteoblasts leading to many complications and an increased mortality risk. Current strategies primarily target osteoclasts. Known osteoclast activating factor PTHrP is expressed by MM cells and BC cells and may contribute to progression. We hypothesized that alteration of PTH receptor signaling should overcome cancers' inhibition of bone formation and decrease cancer growth in bone. BDDP, a novel PTH analog, is being developed for osteoporosis treatment. We determined the ability of BDDP to reverse osteoblast suppression and slow tumor growth in bone with MM and BC models. Methods: In vitro effects of BDDP on bone genes and bone mineralization were tested in a co-culture assay of osteoblastic MC3T3-E1 cells ± human MM.1s cells. After 3 days in proliferative media, they were cultured in differentiation media. At Day 7, the expression of genes with known roles in osteoblast differentiation were assayed by RT-PCR. At Day 25, nodular calcification was stained and measured by a colorimetric assay. In vivo effects of BDDP were evaluated in an intratibial transplant model. MDA-MB-231 BC cells expressing secreted luciferase were injected into the ipsilateral tibiae of Balb/cnu/nu mice. Mice received either BDDP (40μg/kg/d) or vehicle via osmotic pump for 30 days. After euthanasia, mice were subjected to Faxitron digital X-rays to detect osteolytic lesions and DEXA scans to assess bone mineral content (BMC) and bone mineral density (BMD). Tumor-injected and non-injected tibiae were subjected to micro-QCT for 3D tibiae imaging. Results: MM.1s-treated MC3T3-E1 cells showed approximately a 5-fold reduction in osteoblast differentiation gene RUNX2 and a 3-fold reduction in BGLAP. This effect was attenuated by 100 nM BDDP by approximately 4-fold in both Runx2 and BGLAP. BDDP increased nodular calcification. Nodular calcification was suppressed in MM.1s-treated MC3T3-E1 cells. This effect was reversed by BDDP. BDDP did not directly affect MM.1s and MDA-MB-231 growths in culture but showed dramatic tumor suppression in a MDA-MB-231 intratibial transplant model. Tumor burden assayed by serial serum luciferase assay showed BDDP-treated group to be 95% lower than control, at 3 and 4 weeks post-transplant. Tumor-injected tibiae had lytic lesions in all control mice, while there were no obvious lesions in BDDP-treated mice. There were no significant changes in the trabecular bone of non-injected tibiae, whole body composition, BMC or BMD. Conclusion: BDDP reverses osteoblastic suppression by MM cells in vitro, as well as inhibiting tumor growth and preventing local bone destruction in the BC intratibial transplant model, thereby making BDDP a promising potential treatment strategy for metastatic bone cancers. Citation Format: Teja Vallapuri, Colin Crean, John Chirgwin, G. David Roodman, Attaya Suvannasankha. Effects of a bone-anabolic agent on metastatic bone cancer growth [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 693.

Abstract 2613: Integrin beta-3 signaling links chemoresistance and mitochondrial metabolism in breast cancer bone metastases

Abstract We have previously demonstrated that expression of the integrin β3 (β3) subunit is consistently increased in breast cancer (BC) bone metastases across clinical samples and preclinical models. Bone metastases frequently exhibit resistance to chemotherapy. Based on evidence that integrin β3 can function as a promoter of tumor survival and metastasis, we asked whether increased β3 signaling in bone metastases promotes chemoresistance. In established murine bone metastases, the proportion of integrin β3+ tumor cells was increased after docetaxel administration. Genetic deletion of β3 in either MMTV-PyMT-derived BC cells (BO1-FL-GFP, modeling luminal B disease) or 4T1 BC cells (4T1-FL-GFP, modeling triple-negative disease) yielded bone metastases with increased sensitivity to docetaxel treatment in vivo. Retroviral rescue of β3 expression in β3-/- BO1-FL-GFP cells by a signaling-competent human integrin β3 construct (hβ3) restored relative docetaxel chemoresistance in bone metastases. By contrast, expression of a signaling-deficient mutant β3 (Δβ3) failed to restore chemoresistance, suggesting that signaling through β3 is critical to its capacity to promote docetaxel chemoresistance in bone-residing BC cells. Mechanistically, RNAseq analysis of docetaxel response in β3-/- and hβ3-rescued cells revealed β3-mediated enrichment in transcriptional pathways associated with oxidative phosphorylation and metabolism. Direct imaging of mitochondria by super-resolution microscopy and extracellular flux analysis of oxygen consumption rate further confirmed an alternative metabolic response to docetaxel in resistant, β3-expressing tumor cells. mTORC1 plays an important role in mitochondrial biogenesis and cellular metabolism, and can be activated downstream of integrin signaling in certain contexts. Based on transcriptomic data identifying enhanced mTORC1 activity as a possible mediator of β3-dependent metabolic changes, we asked whether mTOR inhibition could restore chemosensitivity in BC bone metastases. In mice bearing chemoresistant, β3-WT metastases, combination of the mTORC1 inhibitor rapamycin with docetaxel yielded synergistic, site-specific attenuation of bone tumor burden. Taken together, our data 1) establish integrin β3 as a mediator of chemoresistance in breast cancer bone metastases, 2) demonstrate a mechanistic link between integrin β3 expression and an alternative metabolic response to docetaxel in resistant cells, and 3) suggest mTORC1 inhibition as a candidate for rational combination with chemotherapy to interrupt treatment resistance in breast cancer bone metastases. Citation Format: Gregory C. Fox, Michael H. Ross, Xinming Su, Yalin Xu, Alison Esser, Elizabeth Cordell, Elizabeth Wilson, Barbara Muz, Ha Dang, Christopher A. Maher, Abdel Kareem Azab, Deborah Veis, Samuel Achilefu, Gregory M. Lanza, Katherine N. Weilbaecher. Integrin beta-3 signaling links chemoresistance and mitochondrial metabolism in breast cancer bone metastases [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2613.

Abstract 321: Novel bone microenvironment model of prostate cancer with chitosan fiber matrix and osteoblast in 3D culture

Abstract BACKGROUND: The interaction between prostate cancer cells and osteoblast is essential for the development of bone metastasis. Recently, novel androgen receptor signal inhibitors (ARSi) have been approved for metastatic castration naïve (mCNPC), or non-metastatic castration resistant prostate cancer (nmCRPC), both of which should be pivotal to investigate the association between bone microenvironment and tumor. We established a novel 3D in vitro culture method reflecting bone microenvironment and evaluated the drug susceptibility of ARSi including enzalutamide, apalutamide, darolutamide, and abiraterone (Abi) with/without dutasteride (Duta). METHODS: GFP-transferred C4-2 (CRPC cell line) and RFP-transferred human osteoblast differentiated from human-mesenchymal stem cell was co-cultured in chitosan nanofiber, a mimicry of 3D scaffold of bone microenvironment, coated culture plate (Cosmo bio Co., LTD). The growth of C4-2 cell was quantified using live-cell imaging and analysis system, Cell3 iMager duos (SCREEN). Abi metabolites including delta-4 abiraterone (D4A) and 3-keto-5-alfa abiraterone in C4-2 cells were measured by ESI-TOF-MS method. RESULTS: We could non-invasively quantify the sustained growth of C4-2 cells at maximum of 30 days. IC50 of each drugs and combination effect of Abi and Duta was evaluated using this model. Combination treatment synergistically inhibited the growth of C2-4 cells compared with each drug alone. D4A, the strongest anti-proliferative metabolite of Abi under the CRPC-specific backdoor pathway, was detected from the treated C4-2 cell. These results were coincided with the effective cases of pharmacokinetics of Abi metabolites in our ongoing phase II clinical trial of combination therapy of Abi with Duta for CRPC (UMIN000027795). Furthermore, combination of abiraterone and dutasteride was most potent cell growth inhibitor than other ARis tested in this model. This model is applying for international patent (C12N 5/09). CONCLUSIONS: Our bone microenvironment model is unique and useful to evaluate the new drug susceptibility testing in prostate cancer cells. This model may help in disclose unknown mechanisms from micro- to clinical bone metastasis in prostate cancer. Citation Format: Masahiro Samoto, Hiroaki Matsumoto, Hiroshi Hirata, Sho Ozawa, Junichi Mori, Ryo Inoue, Seiji Yano, Yoshiaki Yamamoto, Hideyasu Matsuyama. Novel bone microenvironment model of prostate cancer with chitosan fiber matrix and osteoblast in 3D culture [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 321.

Abstract 1240: Runx2 promotes microtubule stability for survival of breast cancer bone metastatic cells

Abstract Bone metastasis of breast cancer causes significant patient mortality. During metastasis, breast cancer cells induce autophagy to survive metabolic stress. Although the core components of the autophagy pathway have been characterized, the regulatory mechanism of autophagy in bone metastatic cancer cells is still unknown. To examine autophagy during bone metastasis, we used a bone metastatic isogenic variant of breast cancer MDA-MB-231 cells isolated from a xenograft tumor mouse model of metastasis. Previously, we and others have shown that Runt-related transcription factor-2 (Runx2) promotes cell survival, cell invasion, and metastatic tumor growth associated osteolysis. Therefore, we examined the regulatory mechanisms of Runx2-mediated autophagy for increased cell survival in the bone microenvironment. Our results show that Runx2 promotes microtubule (MTs) stability to enhance autophagy flux. We show that Runx2 silencing significantly decreases acetylated α-Tubulin (Ac-α-Tub) levels. Ac-α-Tub is a marker of stable MTs, which promotes trafficking of autophagosomes. Ac-α-Tub also increases during cellular stress, such as glucose starvation. We found that Runx2 knockdown cells are able to induce Ac-α-Tub upon glucose starvation but are unable to maintain acetylated polymer mass of MTs upon removal of stress. Furthermore, expression of wild type or transcriptionally inactive Runx2 can restore Ac-polymer of MTs in Runx2 knockdown cells, while C-terminal deletion mutant failed to rescue MT polymer mass. Previous studies have shown that the C-terminal of Runx2 serves a scaffolding function by interacting with MTs and multiple proteins including HDAC6, the deacetylase of α-Tubulin. Interestingly, the expression levels of HDAC6 and αTAT1 (α-tubulin acetyltransferase-1) were not altered with Runx2 silencing, suggesting a transcriptionally independent function for Runx2 for maintaining the MTs stability. As MT targeting agents are often used as chemotherapeutics, we found that treatment with vinblastine, a MT disrupting agent, decreases Ac-polymer MTs with Runx2 silencing or expression of C-terminal mutant Runx2, while WT and transcriptionally inactive Runx2 expressing cells exhibit resistance to the treatment. Conversely, treatment with Docetaxel, a MT stabilizing agent, enhances Ac-α-Tub and polymer MTs. Recent reports have also linked high levels of Ac-α-Tub with aggressive breast cancer. We performed immunohistochemistry for Ac-α-Tub levels in bone metastatic patient samples and found significantly strong Ac-α-Tub positive cells in matched and unmatched bone metastatic tumors compared to the primary tumors. Our findings indicate that inhibition of Runx2 may sensitize metastatic tumors to MT targeting agents, and Runx2 and Ac-α-Tub levels may serve as markers for metastatic tumors to help stratify patients for optimal treatment for bone metastatic tumors. Citation Format: Ahmad Othman, Marcus Winogradzki, Manish Tandon, Jitesh Pratap. Runx2 promotes microtubule stability for survival of breast cancer bone metastatic cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1240.

Abstract 6286: The effects of prednisone, abiraterone acetate and radium-223 dichloride on bone in the intratibial LNCaP prostate cancer model

Abstract Radium-223 dichloride (Ra-223) is a targeted alpha therapy that binds to newly formed bone matrix in bone metastases and induces double-stranded DNA breaks in cancer cells, osteoblasts, and osteoclasts. Ra-223 showed survival benefit in patients with bone-metastatic castration-resistant prostate cancer in a pivotal phase 3 trial. Recently, in a phase 3 trial of Ra-223 in combination with abiraterone acetate (AA) and prednisone/prednisolone (P), an increased risk of fractures was observed, which could be largely diminished by concurrent administration of bone resorption-inhibiting bisphosphonates or denosumab. The aim of this study was to investigate the effects of vehicle, Ra-223, AA, P, AA/P, and Ra-223/AA/P on bone using a mouse model mimicking osteoblastic prostate cancer bone metastases. Male NOD.scid mice were injected intratibially with LNCaP cells. Following stratification based on serum PSA and total bone volume of the tumor-bearing tibia, mice were treated for 28 days. Serum TRACP 5b and PSA levels were measured at multiple time points. At sacrifice, hind limbs were collected to analyze healthy and tumor-bearing bone structure, quality and formation rate by microCT, 3-point bending assay and dynamic histomorphometry, respectively. Also, Ra-223 incorporation was measured. Treatment with AA/P reduced Ra-223 incorporation to bone. PSA levels were similarly reduced at sacrifice upon Ra-223, AA, AA/P, and Ra-223/AA/P treatment indicating the absence of triple combination-specific additive anti-tumor effects. Bone resorption marker TRACP 5b levels increased transiently during the first two weeks of Ra-223/AA/P treatment. Neither bone structure or bone biomechanical quality in healthy or tumor-bearing tibia were affected by Ra-223/AA/P. Regarding dynamic bone formation, trabecular mineralizing surface (MS) was reduced in all groups containing Ra-223, while periosteal MS was reduced in all groups receiving P. However, only Ra-223/AA/P reduced both trabecular and periosteal MS. In line with the inhibition of dynamic bone formation, Ra-223/AA/P treatment decreased the number of osteoblasts. The AA/P treatment-induced reduction of Ra-223 incorporation may mediate the lack of additive anti-tumor effects in the Ra-223/AA/P group. Regarding bone health, Ra-223/AA/P specifically induced a transient increase in bone resorption and inhibited both periosteal and trabecular new bone formation but did not lead to structural or biomechanical bone changes. This preclinical mechanism may nevertheless contribute to the increased fragility observed in the clinics and may explain the beneficial clinical effects of bone resorption-inhibiting bisphosphonates and denosumab. However, several species- and model-related factors may limit the translational relevance of these findings. Citation Format: Mari I. Suominen, Matias Knuuttila, Birgitta Sjöholm, Esa Alhoniemi, Dominik Mumberg, Jussi M. Halleen, Sanna-Maria Käkönen, Arne Scholz. The effects of prednisone, abiraterone acetate and radium-223 dichloride on bone in the intratibial LNCaP prostate cancer model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6286.

Low molecular weight heparin modified bone targeting liposomes for orthotopic osteosarcoma and breast cancer bone metastatic tumors

The standard-of-care chemotherapy is important in the treatment of osteosarcoma and bone metastastic tumors. However, the efficacy is limited by the specific physiological environment of the bone. Thus, developing an efficient antitumor and anti-metastasis chemotherapeutic formulation is desired for treatment of bone tumors. Herein, we utilized the alendronate (ALN) and low molecular weight heparin (LMWH) modified liposomes to deliver the antitumor drug doxorubicin (DOX), where traditionally-believed non-active drug carrier, targeting moiety could also exhibit biological functions and realize anti-tumor and anti-metastasis efficiency synergistically with the antitumor drug. Specifically, ALN could serve as the bone targeting moiety and the therapeutic agents of anti-osteoporosis. LMWH could enhance the blood circulation time of liposomes and exhibit anti-metastasis efficiency. Besides characterization of typical physiochemical properties of the delivery system, both the orthotopic osteosarcoma model and bone metastasis cancer model were adopted to evaluate the in vivo efficacy. The results proved this system could remarkably suppress tumor growth and inhibit tumor metastasis.

Bisphosphonate-functionalized micelles for targeted delivery of curcumin to metastatic bone cancer

Metastatic (secondary) bone cancer is one of the major causes of death in patients with advanced cancer. A lack of options for the targeted delivery of a desired therapeutic payload to multiple tumour modules located in the bone is still one of the foremost hurdles in the treatment/prevention of metastatic bone cancer. Curcumin has a proven anticancer potential with known challenges for application as a pharmaceutical agent. We have previously shown that micellar formulations could overcome some of these challenges and enhances its anti-cancer activity. In this study, we have developed a targeted drug delivery system using bisphosphonate (alendronate) conjugated Pluronic F127 micelles that could efficiently target, and specifically deliver curcumin to the osteolytic tumour microenvironment in the bone. Characterization of the formulation of curcumin-encapsulated alendronate-conjugated micelles demonstrated that the micelles have nanoscale size (∼27 nm) with a positive surface charge (+2.87 mV) and 4% drug loading. The alendronate-conjugated micelles showed significant bone-targeting potential. Rapid binding of the micelles to hydroxyapatite surface suggested that these nanoparticles are promising carriers for effective and targeted delivery of curcumin to osteolytic tumours in the bone.

Personal Medicine and Bone Metastases: Biomarkers, Micro-RNAs and Bone Metastases

Bone metastasis is a major cause of morbidity within solid tumours of the breast, prostate, lung and kidney. Metastasis to the skeleton is associated with a wide range of complications including bone fractures, spinal cord compression, hypercalcaemia and increased bone pain. Improved treatments for bone metastasis, such as the use of anti-bone resorptive bisphosphonate agents, within post-menopausal women have improved disease-free survival; however, these treatments are not without side effects. There is thus a need for biomarkers, which will predict the risk of developing the spread to bone within these cancers. The application of molecular profiling techniques, together with animal model systems and engineered cell-lines has enabled the identification of a series of potential bone-metastasis biomarker molecules predictive of bone metastasis risk. Some of these biomarker candidates have been validated within patient-derived samples providing a step towards clinical utility. Recent developments in multiplex biomarker quantification now enable the simultaneous measurement of up to 96 micro-RNA/protein molecules in a spatially defined manner with single-cell resolution, thus enabling the characterisation of the key molecules active at the sites of pre-metastatic niche formation as well as tumour-stroma signalling. These technologies have considerable potential to inform biomarker discovery. Additionally, a potential future extension of these discoveries could also be the identification of novel drug targets within cancer spread to bone. This chapter summarises recent findings in biomarker discovery within the key bone metastatic cancers (breast, prostate, lung and renal cell carcinoma). Tissue-based and circulating blood-based biomarkers are discussed from the fields of genomics, epigenetic regulation (micro-RNAs) and protein/cell-signalling together with a discussion of the potential future development of these markers towards clinical development.

Targeting the MAPK7/MMP9 axis for metastasis in primary bone cancer

Metastasis is the leading cause of cancer-related death. This multistage process involves contribution from both tumour cells and the tumour stroma to release metastatic cells into the circulation. Circulating tumour cells (CTCs) survive circulatory cytotoxicity, extravasate and colonise secondary sites effecting metastatic outcome. Reprogramming the transcriptomic landscape is a metastatic hallmark, but detecting underlying master regulators that drive pathological gene expression is a key challenge, especially in childhood cancer. Here we used whole tumour plus single-cell RNA-sequencing in primary bone cancer and CTCs to perform weighted gene co-expression network analysis to systematically detect coordinated changes in metastatic transcript expression. This approach with comparisons applied to data collected from cell line models, clinical samples and xenograft mouse models revealed mitogen-activated protein kinase 7/matrix metallopeptidase 9 (MAPK7/MMP9) signalling as a driver for primary bone cancer metastasis. RNA interference knockdown of MAPK7 reduces proliferation, colony formation, migration, tumour growth, macrophage residency/polarisation and lung metastasis. Parallel to these observations were reduction of activated interleukins IL1B, IL6, IL8 plus mesenchymal markers VIM and VEGF in response to MAPK7 loss. Our results implicate a newly discovered, multidimensional MAPK7/MMP9 signalling hub in primary bone cancer metastasis that is clinically actionable.

The Value of Data Mining Technology in the Diagnosis of Bone Metastases from Prostate Cancer Based on Nuclear Medicine Image

With the continuous development of information construction in the medical industry, a large amount of data related to bone metastasis of prostate cancer can be found in the medical database. It includes a large number of inspection indicators, medical images, and background information such as gender, age, height, weight, and previous medical history. The content is very rich and detailed. The nuclear medicine image processing technology and data mining technology are organically combined to study the feature extraction and loading method of nuclear medicine image data, and the classification method of medical image data, thereby assisting doctors in decision-making diagnosis process and improving accuracy. These have important theoretical significance and broad application prospects. Therefore, based on the nuclear medicine imaging data, this study utilized data mining technology to analyse the nuclear medical imaging data of prostate cancer bone metastasis, and finds and summarizes the imaging features and developmental rules of prostate cancer bone metastasis. So, a BP neural network diagnosis matrix for prostate cancer bone metastasis was constructed. This is valuable and meaningful for the diagnosis, treatment and even medical research of bone metastasis of prostate cancer.

Establishment of a serological molecular model for the early diagnosis and progression monitoring of bone metastasis in lung cancer

BackgroundThe prognosis is very poor for lung cancer patients with bone metastasis. Unfortunately, a suitable method has yet to become available for the early diagnosis of bone metastasis in lung cancer patients. The present work describes an attempt to develop a novel model for the early identification of lung cancer patients with bone metastasis risk.MethodsAs the test group, 205 primary lung cancer patients were recruited, of which 127 patients had bone metastasis; the other 78 patients without bone metastasis were set as the negative control. Additionally, 106 healthy volunteers were enrolled as the normal control. Serum levels of several cytokines in the bone microenvironment (CaN, OPG, PTHrP, and IL-6) and bone turnover markers (tP1NP, β-CTx) were detected in all samples by ECLIA or ELISA assay. Receiver operating characteristic (ROC) curves and multivariate analyses were performed to evaluate diagnostic abilities and to assess the attributable risk of bone metastasis for each of these indicators; the diagnostic model was established via logistic regression analysis. The prospective validation group consisted of 44 patients with stage IV primary lung cancer on whom a follow-up of at least 2 years was conducted, during which serum bone biochemical marker concentrations were monitored.ResultsThe serological molecular model for the diagnosis of bone metastasis was logit (p). ROC analysis showed that when logit (p) > 0.452, the area under curve of the model was 0.939 (sensitivity: 85.8%, specificity: 89.7%). Model validation demonstrated accuracy with a high degree of consistency (specificity: 85.7%, specificity: 87.5%, Kappa: 0.770). The average predictive time for bone metastasis occurrence of the model was 9.46 months earlier than that of the bone scan diagnosis. Serum OPG, PTHrP, tP1NP, β-CTx, and the diagnostic model logit (p) were all positively correlated with bone metastasis progression (P < 0.05).ConclusionsThis diagnostic model has the potential to be a simple, non-invasive, and sensitive tool for diagnosing the occurrence and monitoring the progression of bone metastasis in patients with lung cancer.