Anpassung des Knochens nach mechanischer Stimulation im murinen MOPC315.BM Myelommodell

ABSTRACT Osteolytic bone disease (BD) is a hallmark of multiple myeloma (MM), affecting 80% of patients with MM. Osteolytic bone disease develops when tumor cells infiltrate the bone marrow and shift the balance of the bone remodeling process towards massive bone resorption. This results in osteolytic bone lesions that cause non- healing fractures and pain. Bones have the capacity to locally adapt to load changes, self-repair and remodel, as dramatically seen in young tennis athletes with muscle- bone asymmetries in the playing arm. However, it remains unknown if this capacity is conserved in multiple myeloma bone disease (MMBD) ...ZUSAMMENFASSUNG Ein charakteristisches Merkmal des multiplen Myeloms (MM) ist die osteolytische Knochenkrankheit (bone disease, BD), von der rund 80% der Patienten betroffen sind. Diese entsteht durch eine Infiltration des Knochenmarks mit Tumorzellen, die im weiteren Verlauf das Gleichgewicht zwischen Knochenregeneration und - resorption in Richtung einer Knochenresorption verschieben. Der Prozess resultiert letztendlich in osteolytischen Knochenläsionen, die wiederum zu nicht-heilenden Frakturen sowie Schmerzen führen. Die Knochen sind unter physiologischen Bedingungen in der Lage, sich an Belastungsänderungen anzupassen und besitzen zudem eine gute Regenerationsfähigkeit, wie man am Beispiel von jungen Tennisspielern gut erkennen kann, deren Muskel-Skelett-Apparat des Spielerarms asymmetrisch ausgebildet ist („Tennisarm“). Bisher ist unklar, ob diese Anpassungsfähigkeit in der Knochenkrankheit des multiplen Myeloms (multiple myeloma bone disease, MMBD) erhalten ist. ..

Abstract 4260: Sunitinib treatment induces Notch expression and activation in renal carcinoma cell lines

Abstract Introduction. Notch signaling is an evolutionary conserved pathway that plays a central role in stem cell biology, tumor formation, angiogenesis and cell fate decisions. Currently there is not any clear view as to whether Notch plays an oncogenic role in renal cell cancer (RCC). Notch-1 is activated after cytotoxic stimuli and may induce mTor pathway activation, leading to increased cell survival. We have investigated the role of Notch expression and activation in RCC cell lines in response to sunitinib treatment and the role of Notch in the activation of the mTor pathway. We elaborated three cell lines with a different VHL and PTEN mutation status: Caki-1 cells (VHL-wt, PTEN-wt), Caki-2 (VHL-mut, PTEN-wt) and 786-O (VHL-mut, PTEN-mut). Results: When Caki-1 and Caki-2 cells were exposed to sunitinib there was a marked upregulation in the expression of the Notch-1 mRNA and the target transcription factors RUNX1, RBPJ and HES1. The PI3K – mTor – S6K pathway was aslo upregulated. This upregulation was reversed when cells were pre-treated with a gamma-secretase inhibitor. However, both gamma secretase inhibitors and everolimus (an m-Tor inhibitor) had an antagonistic effect when combined with sunitinib (Combination Index &amp;gt;&amp;gt; 1.0). On the other hand, PTEN-mutant 786-O cells have a dysregulated mTor pathway and are more sensitive to inhinition of the m-Tor with everolimus. Sunitinib exposure did not result in further increase of the PI3K-mTor-S6K activation. Interestingly, combination of sunitinib with everolimus was synergistic in 786-O. Conclusions: VHL-wt and VHL-mutant RCC cells treated with sunitinib activate the Notch pathway. There are reports that Notch plays a tumor suppressor role in RCC and our results are on concert with that. Furthermore, Notch seems to regulate m-Tor pathway activation in cells with a wild-type PTEN. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4260. doi:10.1158/1538-7445.AM2011-4260</jats:p

Cytotoxic Evaluation and Determination of Organic and Inorganic Eluates from Restorative Materials

Over the last years, diverse commercial resin-based composites have dominated as dental filling materials. The purpose of the present study was to determine organic and inorganic eluates from five restorative materials using GC/MS and ICP–OES and to compare the effect on cell survival of human gingival fibroblasts of a conventional and a bioactive resin. Five commercially available restorative materials were employed for this study: ActivaTM Bioactive Restorative, ENA HRi, Enamel plus HRi Biofunction, Fuji II LC Capsule, and Fuji IX Capsule. Disks that were polymerized with a curing LED light or left to set were immersed in: 1 mL methanol or artificial saliva for GC/MS analysis, 5mL deionized water for ICP–OES, and 5mL of culture medium for cell viability. Cell viability was investigated with a modified staining sulforhodamine B assay.The following organic substances were detected: ACP, BHT, BPA, 1,4-BDDMA, CQ, DBP, DMABEE, HEMA, MCE, MeHQ, MOPA, MS, TMPTMA, and TPSb and the ions silicon, aluminum, calcium, sodium, and barium. Activa Bioactive Restorative was found to be biocompatible. Elution of organic substances depended on material’s composition, the nature of the solvent and the storage time. Ions’ release depended on material’s composition and storage time. The newly introduced bioactive restorative was found to be more biocompatible

Mechanical Loading Shows Anti-Myeloma Effects While Rescuing Bone Loss with Net Bone Formation in a Myeloma Bone Disease Murine Model

Abstract Osteolytic bone disease (BD) is a hallmark of multiple myeloma (MM) with tumor cells in the bone marrow shifting the balance of the bone remodeling process towards massive bone resorption. As a result, patients develop devastating osteolytic lesions that lead to non-healing bone fractures and pain, affecting life quality and mortality rates. Bones have the capacity to adapt mass and structure to mechanical stimuli, as dramatically seen in young tennis athletes with muscle-bone asymmetries in the playing arm. We have previously shown that tibial mechanical loading rescued bone loss in our murine MOPC315.BM MM model with an advanced osteolytic phenotype. Here, we hypothesize that mechanical strain (1) modulates the bone microenvironment and (2) has antitumor activity in mice. (1) We determined bone formation and bone resorption parameters by time-lapsed microCT analysis to show how skeletal mechanical stimuli control MM bone disease (MMBD) progression over time. (2) To monitor tumor progression, we used non-invasive bioluminescence imaging (BLI) and enzyme-linked immunosorbent assay (ELISA) for detection of MOPC315.BM specific immunoglobulin A (IgA) levels. In our in vivo loading study, we injected MOPC315.BM cells intratibially (i.t.) in BALB/c mice to establish MMBD (n=17) and used PBS-injected (n=13) as well as noninjected mice (n=8) as controls. Eight (MM), seven (PBS) and 8 (noninjected) mice received compressive tibial loading for three weeks while nine (MM) and six (PBS) mice served as nonloaded controls. The bone remodeling response to mechanical loading was investigated by longitudinal in vivo microCT imaging performed every 5 days (at day 13, 18, 23, 28, and 33 after i.t. injection). MicroCT images from day 33 were geometrically registered onto images of day 13 and resampled into the same coordinate system using Amira and scripts written in Matlab for post-processing. Normalized newly mineralized and eroded bone volume (MV/BV, EV/BV), normalized formed and eroded bone surface area (MS/BS, ES/BS), mineralized thickness (MTh) and eroded depth (ED) were quantified. ANOVA was performed to examine the effect of loading and injection. Loading significantly increased the periosteal MV/BV, periosteal and endosteal MS/BS as well as decreased the periosteal EV/BV and periosteal and endocortical ES/BS. Endosteal MV/BV or EV/BV were not affected, which may be due to differences in the local strain environment at the two surfaces. In addition, mechanical stimuli did not influence ED, but led to diminished periosteal EV/BV and periosteal ES/BS suggesting fewer resorption sites in tibiae subjected to loading. Injection significantly affected periosteal and endosteal bone formation and resorption (Fig.1). Significant increases in cortical bone mass of loaded MM mice were accompanied by decreases in tumor load as evidenced by MOPC315.BM specific IgA levels (Fig. 2A). Interestingly, quantification of tibial and whole body bioluminescence signal intensities revealed controlled tumor growth in the loaded left tibia and a further delay of tumor cell dissemination throughout body of MM mice (Fig. 2B). Our data provide evidence that skeletal mechanical stimuli have anti-myeloma effects and rescue osteolytic bone loss in MMBD. The anabolic response to mechanical loads outweighs the anti-resorptive effect of MM cells, suggesting a combination of loading with bone resorption inhibitors in future therapeutic strategies. Disclosures No relevant conflicts of interest to declare. </jats:sec

Cytotoxic Evaluation and Determination of Organic and Inorganic Eluates from Restorative Materials

Over the last years, diverse commercial resin-based composites have dominated as dental filling materials. The purpose of the present study was to determine organic and inorganic eluates from five restorative materials using GC/MS and ICP–OES and to compare the effect on cell survival of human gingival fibroblasts of a conventional and a bioactive resin. Five commercially available restorative materials were employed for this study: ActivaTM Bioactive Restorative, ENA HRi, Enamel plus HRi Biofunction, Fuji II LC Capsule, and Fuji IX Capsule. Disks that were polymerized with a curing LED light or left to set were immersed in: 1 mL methanol or artificial saliva for GC/MS analysis, 5mL deionized water for ICP–OES, and 5mL of culture medium for cell viability. Cell viability was investigated with a modified staining sulforhodamine B assay.The following organic substances were detected: ACP, BHT, BPA, 1,4-BDDMA, CQ, DBP, DMABEE, HEMA, MCE, MeHQ, MOPA, MS, TMPTMA, and TPSb and the ions silicon, aluminum, calcium, sodium, and barium. Activa Bioactive Restorative was found to be biocompatible. Elution of organic substances depended on material’s composition, the nature of the solvent and the storage time. Ions’ release depended on material’s composition and storage time. The newly introduced bioactive restorative was found to be more biocompatible.</jats:p

Prevention of Bone Destruction by Mechanical Loading Is Not Enhanced by the Bruton’s Tyrosine Kinase Inhibitor CC-292 in Myeloma Bone Disease

Limiting bone resorption and regenerating bone tissue are treatment goals in myeloma bone disease (MMBD). Physical stimuli such as mechanical loading prevent bone destruction and enhance bone mass in the MOPC315.BM.Luc model of MMBD. It is unknown whether treatment with the Bruton’s tyrosine kinase inhibitor CC-292 (spebrutinib), which regulates osteoclast differentiation and function, augments the anabolic effect of mechanical loading. CC-292 was administered alone and in combination with axial compressive tibial loading in the MOPC315.BM.Luc model for three weeks. However, neither CC-292 alone nor its use in combination with mechanical loading was more effective in reducing osteolytic bone disease or rescuing bone mass than mechanical stimuli alone, as evidenced by microcomputed tomography (microCT) and histomorphometric analysis. Further studies are needed to investigate novel anti-myeloma and anti-resorptive strategies in combination with physical stimuli to improve treatment of MMBD.</jats:p

Prevention of Bone Destruction by Mechanical Loading Is Not Enhanced by the Bruton’s Tyrosine Kinase Inhibitor CC-292 in Myeloma Bone Disease

Limiting bone resorption and regenerating bone tissue are treatment goals in myeloma bone disease (MMBD). Physical stimuli such as mechanical loading prevent bone destruction and enhance bone mass in the MOPC315.BM.Luc model of MMBD. It is unknown whether treatment with the Bruton’s tyrosine kinase inhibitor CC-292 (spebrutinib), which regulates osteoclast differentiation and function, augments the anabolic effect of mechanical loading. CC-292 was administered alone and in combination with axial compressive tibial loading in the MOPC315.BM.Luc model for three weeks. However, neither CC-292 alone nor its use in combination with mechanical loading was more effective in reducing osteolytic bone disease or rescuing bone mass than mechanical stimuli alone, as evidenced by microcomputed tomography (microCT) and histomorphometric analysis. Further studies are needed to investigate novel anti-myeloma and anti-resorptive strategies in combination with physical stimuli to improve treatment of MMBD

Interactions between Muscle and Bone—Where Physics Meets Biology

Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment

An Early Myeloma Bone Disease Model in Skeletally Mature Mice as a Platform for Biomaterial Characterization of the Extracellular Matrix

Multiple myeloma (MM) bone disease is characterized by osteolytic bone tissue destruction resulting in bone pain, fractures, vertebral collapse, and spinal cord compression in patients. Upon initial diagnosis of MM, almost 80% of patients suffer from bone disease. Earlier diagnosis and intervention in MM bone disease would potentially improve treatment outcome and patient survival. New preclinical models are needed for developing novel diagnostic markers of bone structural changes as early as possible in the disease course. Here, we report a proof-of-concept, syngeneic, intrafemoral MOPC315.BM MM murine model in skeletally mature BALB/c mice for detection and characterization of very early changes in the extracellular matrix (ECM) of MM-injected animals. Bioluminescence imaging (BLI) in vivo confirmed myeloma engraftment in 100% of the animals with high osteoclast activity within 21 days after tumor cell inoculation. Early signs of aggressive bone turnover were observed on the outer bone surfaces by high-resolution microcomputed tomography (microCT). Synchrotron phase contrast-enhanced microcomputer tomography (PCE-CT) revealed very local microarchitecture differences highlighting numerous active sites of erosion and new bone at the micrometer scale. Correlative backscattered electron imaging (BSE) and confocal laser scanning microscopy allowed direct comparison of mineralized and nonmineralized matrix changes in the cortical bone. The osteocyte lacunar-canalicular network (OLCN) architecture was disorganized, and irregular-shaped osteocyte lacunae were observed in MM-injected bones after 21 days. Our model provides a potential platform to further evaluate pathological MM bone lesion development at the micro- and ultrastructural levels. These promising results make it possible to combine material science and pharmacological investigations that may improve early detection and treatment of MM bone disease.</jats:p