Inhibition of RANKL blocks skeletal tumor progression and improves survival in a mouse model of breast cancer bone metastasis

Bone metastases cause severe skeletal morbidity including fractures and hypercalcemia. Tumor cells in bone induce activation of osteoclasts, which mediate bone resorption and release of growth factors from bone matrix, resulting in a “vicious cycle” of bone breakdown and tumor proliferation. Receptor activator of NF-κB ligand (RANKL) is an essential mediator of osteoclast formation, function, and survival, and is blocked by a soluble decoy receptor, osteoprotegerin (OPG). In human malignancies that metastasize to bone, dysregulation of the RANK/RANKL/OPG pathway can increase the RANKL:OPG ratio, a condition which favors excessive osteolysis. In a mouse model of bone metastasis, RANKL protein levels in MDA-MB-231 (MDA-231) tumor-bearing bones were significantly higher than tumor-free bones. The resulting tumor-induced osteoclastogenesis and osteolysis was dose-dependently inhibited by recombinant OPG-Fc treatment, supporting the essential role for RANKL in this process. Using bioluminescence imaging in a mouse model of metastasis, we monitored the anti-tumor efficacy of RANKL inhibition on MDA-231 human breast cancer cells in a temporal manner. Treatment with OPG-Fc in vivo inhibited growth of MDA-231 tumor cells in bony sites when given both as a preventative (dosed day 0) and as a therapeutic agent for established bone metastases (dosed day 7). One mechanism by which RANKL inhibition reduced tumor burden appears to be indirect through inhibition of the “vicious cycle” and involved an increase in tumor cell apoptosis, as measured by active caspase-3. Here, we demonstrate for the first time that OPG-Fc treatment of mice with established bone metastases resulted in an overall improvement in survival.     

Tamoxifen stimulates calcitonin-producing thyroid C-cells and prevents trabecular bone loss in a rat model of androgen deficiency

Thyroid C-cells produce calcitonin (CT), a hypocalcemic hormone, that acts as an inhibitor of bone resorption. In this study, we investigated the effects of tamoxifen (TAM) as a selective estrogen receptor modulator on thyroid C-cells, trabecular bone and biochemical markers of bone metabolism in an animal model of androgen deficiency, represented by middle-aged orchidectomized (Orx) rats. Fifteen-month-old male Wistar rats were divided into: Orx and sham-operated (SO) groups. Rats from one Orx group were injected subcutaneously with TAM citrate (Orx + TAM; 0.3 mg kg⁻¹ b.w.), while the rats from SO and a second Orx group received vehicle alone, once a day for 3 weeks. The peroxidase–antiperoxidase method was applied for localization of CT in C-cells. Thyroid C-cells were morphometrically and ultrastructurally analyzed. An ImageJ image-processing program was used to measure bone histomorphometric parameters. Blood serum samples were analyzed for CT, osteocalcin (OC), calcium (Ca²⁺) and phosphorus (P). Urinary Ca²⁺ concentrations were measured. TAM treatment significantly increased thyroid C-cell volume (V_c) and serum CT when compared with vehicle-treated Orx rats. Analysis of trabecular microarchitecture of the tibia showed that administration of TAM significantly increased cancellous bone area, trabecular thickness and trabecular number, whereas trabecular separation was significantly decreased compared with vehicle-treated Orx rats. Serum OC and urinary Ca²⁺ concentrations were significantly lower in comparison with the control Orx group. These results indicate that in our rat model of androgen deficiency, TAM stimulated calcitonin-producing thyroid C-cells and increased trabecular bone mass.     

Intermedin attenuates myocardial infarction through activation of autophagy in a rat model of ischemic heart failure via both cAMP and MAPK/ERK1/2 pathways

Intermedin is a proopiomelanocortin-derived peptide before opioid promoting cortical hormone, its main function embodies in mononuclear macrophages and neutrophilic granulocytes to inhibit the proinflammatory cytokines. The aim of this study is to determine intermedin attenuates myocardial infarction and its related mechanisms in a rat model of ischemic heart failure. After rat model of ischemic heart failure was set up, myocardial infarction, blood levels of activities of creatine kinase (CK), the MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin T (cTnT) were effectively reduced by treatment with intermedin. Tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) in a rat model of ischemic heart failure were recovered by pretreatment with intermedin. Administrate of intermedin availably promoted cAMP contents and suppressed caspase-3 protein in ischemic heart failure rat. ERK1/2 and LC3 protein expression were significantly activated and autophagy was significantly promoted by intermedin in a rat model of ischemic heart failure. These results indicate that intermedin protected rat heart, attenuates myocardial infarction from ischemic heart failure in the rat model. The underlying mechanisms may include upregulation of cAMP, ERK1/2 and LC3 protein expression and activating of autophagy.     

Curcumin improves the recovery of motor function and reduces spinal cord edema in a rat acute spinal cord injury model by inhibiting the JAK/STAT signaling pathway

Curcumin, a yellow pigment extracted from Carcuma longa, has been demonstrated to have extensive pharmacological activity in various studies, and it exhibits protective effects on injuries involving a number of human organs. The present study was designed to evaluate the potential effect and underlying mechanism of curcumin on the motor function and spinal cord edema in a rat acute spinal cord injury (SCI) model. The SCI model was induced by a heavy object falling. At 30 min after the SCI was successfully induced, the animals were intraperitoneally given 40 mg/kg curcumin. The Basso, Beattie and Bresnahan scores showed that curcumin moderately improved the recovery of the motor function in the injured rats, and hematoxylin–eosin staining demonstrated the role of this compound in reducing the hemorrhage, edema and neutrophil infiltration of the traumatic spinal cord. Furthermore, curcumin also inhibited the SCI-associated aquaporin – 4 (AQP4) overexpression and glial fibrillary acidic protein (GFAP) and repressed the unusual activation of the JAK/STAT signaling pathway. In conclusion, our data demonstrate that curcumin exhibits a moderately protective effect on spinal cord injury, and this effect might be related to the inhibition of overexpressed AQP4 and GFAP and the activated JAK/STAT signaling pathway. Curcumin may have potential for use as a therapeutic option for spinal cord injuries.     

绿色荧光蛋白转基因小鼠CD34+/CD45+细胞在脊髓全横断大鼠模型中的存活及迁移

目的:探讨CD34⁺/CD45⁺细胞移植入脊髓全横断大鼠模型后的存活、迁移及分布情况。方法:体外培养绿色荧光蛋白（GFP）转基因小鼠骨髓细胞，经CD34、CD45单克隆抗体鉴定后移植入脊髓全横断大鼠模型脊髓横断处尾侧，分别在术后24 h、48 h、1周、2周、4周和8周行左心腔内灌注，取出脊髓，连续切片（片厚 10 μm），置于荧光显微镜下观察切片中有无绿色荧光细胞，并观察荧光细胞的分布范围；用免疫组化法检测CD34⁺/CD45⁺细胞的存活。 结果:脊髓横断处头尾两侧均可见绿色荧光细胞，且多分布于灰质中，散在或聚集成片；免疫组化法可见切片中有CD34⁺/CD45⁺细胞散在。 结论: CD34⁺/CD45⁺细胞可在脊髓全横断大鼠模型的脊髓中存活，并可迁移至脊髓横断处头侧，且随时间的延长迁移距离有所增加。