破骨细胞体外分离培养及其骨吸收活动的观察

目的 建立大鼠破骨细胞体外分离培养方法，为体外研究破骨细胞骨吸收机理奠定基础。方法 采用出生24h内的Wistar大鼠，从其四肢长骨中分离出破骨细胞，与盖玻片、骨磨片共同培养，观察破骨细胞的形态结构及体外骨吸收活性。结果 相差显微镜及光镜观察到分离的细胞含多个核，能够移动，胞浆有伪足样突起，这些细胞用目前公认的鉴定破骨细胞的标志—抗酒石酸酸性磷酸酶染色呈阳性反应，扫描电镜观察到这些细胞能在骨片上形成典型的骨吸收陷窝。结论 用此方法分离培养的细胞为具有骨吸收活性的破骨细胞。     

肿瘤相关性高血钙因子

肿瘤疾病常伴有体液高钙综合征。目前发现某些肿瘤细胞可产生或刺激机体正常细胞产生与高血钙有关的体液因子,这些体液因子作用于骨质交换过程,主要通过促使破骨细胞形成、骨质吸收增加而导致体液钙浓度增高。     

唑来膦酸治疗恶性肿瘤骨转移临床应用新进展

唑来膦酸属于第三代双膦酸盐.治疗恶性肿瘤骨转移临床疗效确切,应用前景广泛.唑来膦酸在体外可抑制破骨细胞活动,诱导破骨细胞调亡;还可以抑制由肿瘤释放的多种刺激因子引起的破骨细胞活动增强和骨钙释放;缓解实体瘤患者骨转移引起骨痛,起效迅速,效果明显.     

沙戈匹隆通过抑制肿瘤细胞生长和骨质吸收从而抑制乳腺癌骨转移和骨质破坏

乳腺癌最易发生骨转移（75％）,患者生存时间短,仅为2年。骨转移最常见的症状是骨并发症和骨痛,严重影响患者的生存质量。乳腺癌骨转移中存在着“邪恶循环”：肿瘤细胞释放甲状旁腺激素相关蛋白等促进破骨细胞活性,从而造成骨质破坏;而骨质吸收破坏后可释放出生长因子,又进一步促进肿瘤细胞的生长。因此,只有同时抑制肿瘤细胞生长以及破骨细胞活性才能有效抑制骨转移发生。紫杉醇类是目前治疗乳腺癌转移最常用的药物,但存在耐药性高、有效率低（0％～30%）等诸多不足。     

17β-雌二醇对破骨细胞骨架和骨吸收功能影响的实验研究

目的　研究17β-雌二醇对体外培养破骨细胞细胞骨架的影响,以及这种影响与骨吸收功能之间的关系。方法　在破骨细胞培养液中加入不同浓度的17β-雌二醇,用F-actin特异性抗体进行免疫荧光染色,激光共聚焦显微镜观察破骨细胞细胞骨架的变化情况,同时用扫描电镜观察破骨细胞在骨片形成骨吸收陷窝数目及面积的变化。结果　随着17β-雌二醇浓度的升高,实验组破骨细胞F-actin相对荧光强度从(89 6±7 5)%下降至(34 7±5 4)% (与对照组荧光强度相比),细胞内微丝收缩变短,排列紊乱,细胞波状缘消失,破骨细胞伸展面积从(1289±53)μm2 /细胞核下降至(406±42)μm2 /细胞核,同时,骨吸收陷窝的数目和面积从(131 5 ±11 7)个/片和(2157±51)μm2 减少到(16 8±4 0 )个/片和(965±75)μm2。生理浓度(10-7mol/l)及其以上17β-雌二醇处理组与对照组比较,差异有显著性(P<0 01 )。结论　17β-雌二醇影响破骨细胞内细胞骨架的结构,下调F-actin的表达,降低破骨细胞的活动能力,从而抑制破骨细胞的骨吸收功能。     

胫骨内接种建立乳腺癌骨转移大鼠模型的特点

目的研究胫骨内接种MRMT-1细胞制作的乳腺癌骨转移大鼠模型在行为学、影像学、核医学、病理学和分子生物学等方面的特点。方法使用雌性SD大鼠,随机分为假手术组和模型组,使用胫骨内注射法制成乳腺癌骨转移模型。造模后第19天时进行疼痛测定;第21天取材,测定肿瘤体积,通过影像技术评估骨质缺损程度,核医学测定骨矿物质含量(BMC)和骨密度(BMD),HE染色观察形态,抗酒石酸酸性磷酸酶(TRAP)染色并计数破骨细胞,免疫组化法测定增殖细胞核抗原(PCNA)、护骨素(OPG)和核因子kB受体活化因子配体(RANKL),荧光实时定量RT-PCR测定甲状旁腺激素相关蛋白(PTHrP)。结果模型组在造模后第19天已出现机械痛觉超敏、机械痛觉过敏和热痛觉过敏(P0.01)。第21天取材后胫骨影像评分升高(P0.01),BMD下降(P0.05);肉眼观察肿瘤生长明显(P0.01),镜下可见溶骨病变为主的混合性骨质破坏;破骨细胞数量和活性增加(P0.01),PTHrP、OPG水平与OPG/RANKL比值均下降(P0.05、P0.01),而RANKL无明显变化。结论乳腺癌骨转移大鼠模型具有疼痛和骨质破坏的表现,但未表现出PTHrP和RANKL升高,其损伤途径是通过抑制OPG破坏了OPG-RANKL-RANK系统的平衡,引起破骨细胞过度激活,造成骨吸收作用亢进。     

肺癌A549细胞诱导RAW264.7破骨细胞分化中AMPK信号通路的作用

目的:探讨AMPK信号通路在体外肺癌细胞诱导破骨细胞分化中的作用。方法:将肺癌A549细胞与RAW264.7细胞共培养后随机分为阴性对照组、阳性对照组、AICAR组,药物干预后行TRAP染色观察破骨细胞的分化,流式细胞仪观察破骨细胞细胞凋亡情况,qPCR检测破骨细胞AMPK、mTOR和CTSK mRNA的表达,Western blot检测破骨细胞AMPK、p-AMPK、mTOR和p-mTOR蛋白的表达。结果:与阴性对照组比较,AICAR组破骨细胞数明显减少,差异具有统计学意义（P＜0.05）;对诱导破骨细胞凋亡的作用无差异;上调AMPK的mRNA和蛋白表达,下调mTOR的mRNA和蛋白表达,差异具有统计学意义（P＜0.05）。结论:AICAR可以抑制肺癌细胞诱导破骨细胞分化,而AMPK/mTOR信号通路可能参与了肺癌细胞诱导破骨细胞分化过程。     

硼替佐米对多发性骨髓瘤患者破骨细胞生成的影响及机制研究

目的:观察多发性骨髓瘤(multiple myeloma,MM)患者破骨细胞在体外诱导分化成熟过程中,硼替佐米(Bortezomib,Btzmb)对其分化和功能的影响,以及破骨细胞分化过程中上游关键信号分子肿瘤坏死因子受体相关蛋白6(tumor necrosis factor receptor-associated factor 6,TRAF6)的改变.方法:患者外周血单个核细胞在经核因子KB受体活化因子配体(receptor activator of NF-kB ligand,RANKL)及巨噬细胞集落刺激因子(macmphage colony stimulating factor,M-CSF)诱导后向破骨细胞分化过程中,采用不同剂量的Btzmb进行处理,观察抗酒石酸酸性磷酸酶(tartrateresistant acid phosphatase,TRAP)染色阳性的破骨细胞数量,检测培养液中的TRAP活性,并观察骨片上骨陷窝数量的变化.采用Westem印迹和RT-PCR法,分析Btzmb对破骨前体细胞中TRAF6蛋白和mRNA的影响.结果:2.5和5 nmol/L Btzmb组破骨细胞数量分别为(157±21)和(98±15)个,较对照组(307±25)明显减少(P均＜0.05),骨陷窝形成数量分别为对照组的(53±24)%和(29±7)%(P均＜0.05),上清液中破骨细胞活性分别为对照组的(86±24)%和(60±25)%(P均＜0.05).破骨前体细胞经Btzmb处理后观察24 h,TRAF6蛋白活性逐渐降低,TRAF6 mRNA水平也有所下降.结论:Btzmb抑制MM患者破骨细胞的分化和功能,该作用可能与TRAF6有关.     

同种异体骨移植后骨吸收和破骨细胞的形态学特点

目的探讨骨移植后骨吸收和破骨细胞的型态学特点。方法利用扫描电镜,结合光镜,观察8例临床植骨后因严重骨吸收被取出的标本,5例人类正常骨标本和20例大鼠肌内埋入的骨标本,分析严重骨吸收过程中破骨细胞和破骨区表面的形态学特征,以及破骨细胞的形态学演变。结果与正常对照骨标本不同,骨吸收部位有大量幼稚的单核破骨细胞聚集,伴有表面结构变异退变,内部纤维裸露和红细胞吞噬破骨区表现为局灶性切割而不是弥漫性骨质疏松。结论破骨的特点是出现单核破骨细胞和局灶性切割。     

伊班膦酸钠及其在肿瘤相关疾病中的应用

伊班膦酸钠系第三代含氮双膦酸盐药物,能强效抑制破骨细胞活性并诱导破骨细胞凋亡;能抑制肿瘤细胞分泌产生基质金属蛋白酶、血管内皮生长因子等活性物质,抑制骨溶解过程;能抑制乳腺癌细胞、前列腺癌细胞和骨髓瘤细胞对骨质的粘附和侵袭作用,并诱导上述肿瘤细胞凋亡,防止肿瘤骨转移;能防止骨质丢失,并通过对骨的二次性矿化作用,显著增加骨密度和改善骨的机械特性,用于预防和治疗骨质疏松症等.现综述近年来伊班膦酸钠的基础研究及其在肿瘤相关疾病中的临床应用.     

Prolonged decrease of serum calcium concentration by murine gamma-interferon in hypercalcemic, human tumor (EC-GI)-bearing nude mice.

Murine gamma-interferon (MuIFN-gamma) is a potent inhibitor of bone resorption induced by interleukin 1 and parathyroid hormone-related protein in vitro. To investigate whether MuIFN-gamma is also effective in vivo, the cytokine was injected s.c. into hypercalcemic, tumor (EC-GI)-bearing nude mice, in which parathyroid hormone-related protein and interleukin 1 alpha are synergistically responsible for causing humoral hypercalcemia. When MuIFN-gamma was injected s.c. at a dose of 1 to 20 x 10(4) units for 5 days consecutively, serum calcium concentrations in the tumor-bearing mice decreased in a dose-dependent manner. The minimal effective dose was 5 x 10(4) units/mouse. Unlike calcitonin, which decreased the serum calcium concentration for only 1 to 2 days despite continuous daily injections, MuIFN-gamma decreased it for more than 7 days even after the injections had been stopped. Human gamma-interferon was completely ineffective. The decrease in serum calcium concentration was accompanied by a decrease in urinary calcium excretion. Histological examination of the femur revealed a decreased number of osteoclasts in the MuIFN-gamma-treated mice. Furthermore, MuIFN-gamma, when injected into nude mice or normal mice at a dose of 15 x 10(4) units for 3 days, almost completely abolished the formation of multinucleated osteoclast-like cells in vitro. These findings suggest that MuIFN-gamma suppresses the formation and maturation of osteoclasts and inhibits osteoclastic bone resorption, resulting in the prolonged decrease of serum calcium concentration seen in hypercalcemic, tumor-bearing nude mice. Therefore, bone resorption inhibitors like MuIFN-gamma, which ameliorate humoral hypercalcemia without an escape phenomenon, are potentially useful for the treatment of malignancy-associated hypercalcemia.     

Hypercalcemia and osteoclast proliferation in adult T-cell leukemia

Eighteen autopsy cases of adult T-cell leukemia (ATL) were investigated clinicopathologically. Thirteen of the patients had hypercalcemia during their clinical course. Nine of the thirteen had a high level of serum calcium at the terminal stage, even after extensive chemotherapy. Microscopic examination of the bone revealed proliferation of osteoclasts and bone resorption in eight patients. No osteoclast proliferation or bone resorption was found in the other nine normocalcemic patients. The infiltration of ATL cells was observed in only two patients--one was hypercalcemic and the other, normocalcemic. The factors affecting the serum calcium level were examined in two hypercalcemic patients. Hypercalcemia could not be accounted for by parathyroid hormone or prostaglandins E levels, which were in the normal range, or by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, which were low. Our findings are consistent with the mechanism proposed by several investigators, that the malignant T-lymphocytes produced an osteoclast-activating-factor-like substance that caused osteoclast proliferation and hypercalcemia.     

Role of RANKL-induced osteoclast formation and MMP-dependent matrix degradation in bone destruction by breast cancer metastasis

Bone metastasis of breast cancer induces severe osteolysis with increased bone resorption. Osteoclast differentiation regulated by the receptor activator of NF-kappaB ligand (RANKL) in osteoblasts and matrix degradation induced by matrix metalloproteinases (MMPs) are thought to be involved in the process of bone resorption. When nude mice were inoculated with human breast cancer cells, MDA-MB-231(MDA-231), numerous osteoclasts resorbed bone and the degradation of the bone matrix markedly progressed in the femur and tibia with metastasis of the MDA-231 tumour. The expression of RANKL, MMP-13 and membrane-type 1-MMP mRNA was markedly elevated in bone with metastasis. When MDA-231 cells were cocultured with mouse calvaria, MDA-231 markedly induced bone resorption measured by calcium release from the calvaria, and the expression of RANKL, MMP-2 and MMP-13 was elevated in the calvaria after the coculture. The separation of MDA-231 from the calvaria using filter insert showed decreased bone resorption, suggesting that cell-to-cell interaction is essential for cancer-induced bone resorption. Adding MDA-231 cells to bone marrow cultures markedly induced osteoclast formation, and the expression of RANKL in osteoblasts was enhanced by contact with the cell surface of MDA-231 cells. These results indicate that RANKL-induced osteoclast formation and MMP-dependent matrix degradation are associated with osteolysis because of bone metastasis of breast cancer.     

Osteoclast-like cell formation by circulating myeloma B lymphocytes: role of RANK-L

Excessive bone resorption in multiple myeloma (MM), a malignancy of B lymphoid origin, is mediated through osteoclasts, which respond to local osteoclast-activating factors produced by tumor cells within the bone marrow microenvironment. Direct bone resorption by myeloma cells is investigated in the present study, since a connection between B lymphocytes and osteoclast differentiation pathways has been recently postulated in mice. Peripheral CD19+ B lymphocytes isolated from 10 myeloma patients with multiple osteolytic lesions and 10 healthy donors were cultured in the presence of M-CSF and RANK-L, two major osteoclast-activating factors. The TRAP expression and resorption of bone substrates were employed to evaluate osteoclast differentiation. MM patients were characterized by the presence of circulating B lymphocytes endowed with both phenotypical and functional properties of osteoclast-like cells in vitro when stimulated with RANK-L. The absence of these characteristics in B lymphocytes from healthy donors indicates that the transformation can be ascribed to the presence of clonogenic B cells in patients with MM. Clonotypic B lymphocytes may contribute to the pathogenesis of bone disease in MM by acting as RANK-L-dependent osteoclast progenitors.     

Osteoclast-mediated osteolysis in bone metastasis from renal cell carcinoma

Osteolytic characteristics of bone metastasis from renal cell carcinoma were morphologically and biochemically investigated. First, undecalcified ground sections of bone metastases were made from four patients with renal cell carcinoma. Second, renal cell carcinoma cell line (RCC-K1) was established from one of the four patients, and its effect on bone resorption in vitro was examined. Marked proliferation and activation of osteoclasts around the tumor cells was histologically demonstrated. Conditioned medium from the RCC-K1 cells contained potent bone-resorbing activity in vitro. The activity was reduced to basal level by calcitonin, but was not blocked by indomethacin. The activity was lost after dialysis (MW cutoff 3500), while it was retained after 2 weeks of storage. Levels of prostaglandin E2 and 1,25-dihydroxyvitamin D of the RCC-K1-conditioned medium were insufficient to cause bone resorption in vitro. The conditioned medium did not stimulate cAMP accumulation in rat osteoblastic cells. These results suggest that renal cell carcinoma causes bone destruction through the stimulation of osteoclasts by locally secreting an unknown humoral factor or factors.     

Guggulsterone inhibits osteoclastogenesis induced by receptor activator of nuclear factor-kappaB ligand and by tumor cells by suppressing nuclear factor-kappaB activation.

Bone resorption is commonly associated with aging and with certain types of cancer, including multiple myeloma and breast cancer. What induces bone resorption is not fully understood, but the role of osteoclasts is well established. Recently, receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL), a member of the tumor necrosis factor superfamily, was implicated as a major mediator of bone resorption, suggesting that agents that can suppress RANKL signaling have the potential to inhibit bone resorption or osteoclastogenesis. Guggulsterone [4,17(20)-pregnadiene-3,16-dione], isolated from the guggul tree Commiphora mukul and used to treat osteoarthritis and bone fractures, was recently shown to antagonize the farnesoid X receptor, decrease the expression of bile acid-activated genes, and suppress the NF-kappaB activation induced by various carcinogens. We investigated whether guggulsterone could modulate RANKL signaling and osteoclastogenesis induced by RANKL or tumor cells. We found that treatment of monocytes with guggulsterone suppressed RANKL-activated NF-kappaB activation (as indicated by gel-shift assay) and that this suppression correlated with inhibition of IkappaBalpha kinase and phosphorylation and degradation of IkappaBalpha, an inhibitor of NF-kappaB. Guggulsterone also suppressed the differentiation of monocytes to osteoclasts in a dose-dependent and time-dependent manner. Suppression of osteoclastogenesis by the NF-kappaB-specific inhibitory peptide implies a link between NF-kappaB and osteoclastogenesis. Finally, differentiation to osteoclasts induced by coincubating human breast tumor cells (MDA-MB-468) or human multiple myeloma (U266) cells with monocytes was also completely suppressed by guggulsterone. Collectively, our results indicate that guggulsterone suppresses RANKL and tumor cell-induced osteoclastogenesis by suppressing the activation of NF-kappaB.     

Pulse treatment with the proteasome inhibitor bortezomib inhibits osteoclast resorptive activity in clinically relevant conditions

Myeloma bone disease is due to bone degradation by osteoclasts, and absence of repair by bone forming osteoblasts. Recent observations suggest that the anti-myeloma drug bortezomib, a proteasome inhibitor, stimulates bone formation and may inhibit bone resorption. Here, we tested bortezomib on cultured osteoclasts in conditions mimicking the pulse treatment used in the clinic, thereby avoiding continuous proteasome inhibition and unselective toxicity. A 3 h pulse with 25 nM bortezomib followed by a 3-day culture in its absence markedly inhibited osteoclast activity as evaluated through bone resorption, TRAcP release, and RANKL-induced NF-kappaB translocation into nuclei, an event dependent on proteasomes and critical for osteoclast function. The effect on TRAcP was maximal during the first 24 h post-pulse, and then tended to subside. Importantly, applying this pulse treatment to cultured myeloma cells drastically reduced their survival. We measured next the levels of two bone resorption markers in patients during the 3 days following five and seven therapeutic bortezomib administrations, respectively. These levels decreased significantly already 1-2 days after injection, and then increased, showing temporary inhibition of osteoclast activity and paralleling the in vitro effect on TRAcP. Our study demonstrates a direct inhibition of osteoclasts by bortezomib in conditions relevant to treatment of myeloma.     

Effect of combination therapy with a novel bisphosphonate, minodronate (YM529), and docetaxel on a model of bone metastasis by human transitional cell carcinoma.

PURPOSE: Transitional cell carcinoma (TCC) of the urinary tract is a chemosensitive tumor. Most deaths from TCC of the urinary tract are caused by metastasis, which is resistant to conventional chemotherapy. Frequent sites of metastases from TCC of the urinary tract are regional lymph nodes, liver, lung, and bone. Of these distant metastases, bone metastasis is consistently resistant to cisplatin-based conventional chemotherapy. Therefore, in this study, we investigated whether or not a newly developed minodronate, YM529, could prevent osteolytic bone metastasis of human TCC and also enhance the effect of docetaxel in a bone tumor model of athymic nude mice. EXPERIMENTAL DESIGN: In the present study, we evaluated the effect of in vitro treatment with minodronate and/or docetaxel on the proliferation by cell count, the induction of apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and the biological activity of osteoclast by pit formation assay in human bladder cancer cell line, UMUC-14, and mouse osteoclast cells. In vivo, we examined the effect of minodronate in a bone tumor model of athymic nude mice, in which the percutaneous intraosseal injection in the tibia of UMUC-14, leads to osteolytic bone tumor, as a bone metastasis model. To examine whether or not minodronate could inhibit tumorigenicity and enhance the effect of the chemotherapeutic agent, docetaxel, we gave minodronate i.p. and/or docetaxel i.p. to nude mice 3 days after an intraosseal tumor implantation. Moreover, proliferation and the induction of apoptosis of cancer cells and osteoclasts in bone tumors were determined by immunohistochemistry and the TUNEL assay. RESULTS: In vitro: In vitro treatment with docetaxel inhibited proliferation and resorption pit-forming activity and induced apoptosis of mouse osteoclast cells and UMUC-14 cells. In vitro treatment with minodronate inhibited proliferation and activity and induced apoptosis of mouse osteoclast cells but not UMUC-14 cells. The treatment with minodronate enhanced the inhibition of proliferation and activity by docetaxel in osteoclasts. In vivo: In vivo combination therapy with docetaxel and minodronate significantly reduced the tumor incidence compared with the control (P < 0.05) and also growth of intraossal TCC in athymic nude mice compared with the control (P < 0.001), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). Drug-induced body weight loss was not significantly different in any treatment group. Therapy with minodronate significantly enhanced inhibition of proliferation by docetaxel in osteoclasts of bone tumors compared with the control (P < 0.01), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). CONCLUSIONS: These studies indicate that combination therapy with minodronate and docetaxel may be beneficial in patients with bone metastasis of human TCC in the urinary tract.     

Vascular endothelial growth factor acts as an osteolytic factor in breast cancer metastases to bone

Vascular endothelial growth factor (VEGF) is a proangiogenic cytokine that is expressed highly in many solid tumours often correlating with a poor prognosis. In this study, we investigated the expression of VEGF and its receptors in bone metastases from primary human breast tumours and further characterised its effects on osteoclasts in vitro. Breast cancer metastases to bone were immunohistochemically stained for VEGF, its receptors VEGFR1 and 2 (vascular endothelial growth factor receptor 1 and 2), demonstrating that breast cancer metastases express VEGF strongly and that surrounding osteoclasts express both VEGFR1 and VEGFR2. RAW 264.7 cells (mouse monocyte cell line) and human peripheral blood mononuclear cells (PBMCs) were cultured with VEGF, RANKL and M-CSF. VEGF and RANKL together induced differentiation of multinucleated, tartrate-resistant acid phophatase (TRAP)-positive cells in similar numbers to M-CSF and RANKL. The PBMCs were also able to significantly stimulate resorption of mineralised matrix after treatment with M-CSF with RANKL and VEGF with RANKL. We have shown that VEGF in the presence of RANKL supports PBMC differentiation into osteoclast-like cells, able to resorb substrate. Vascular endothelial growth factor may therefore play a role in physiological bone resorption and in pathological situations. Consequently, VEGF signalling may be a therapeutic target for osteoclast inhibition in conditions such as tumour osteolysis.     

Cilengitide inhibits metastatic bone colonization in a nude rat model

Integrins αvβ3 and αvβ5 are considered to play an important role in the pathogenesis of breast cancer bone metastases. This study investigates the effects of the αvβ3/αvβ5 integrin-specific inhibitor cilengitide during early metastatic bone colonization. The impact of cilengitide on the migration, invasion and proliferation of MDA-MB-231 human breast carcinoma cells as well as on bone resorption by osteoclasts was investigated in vitro. For in vivo experiments, nude rats were treated with cilengitide for 30 days starting one day after site-specific tumor cell inoculation in the hind leg, and the course of metastatic changes in bone was followed using flat-panel volumetric computed tomography (VCT) and magnetic resonance imaging (MRI). Vascular changes in bone metastases were investigated using dynamic contrast-enhanced (DCE-) MRI-derived parameters amplitude A and exchange rate coefficient kep. In vitro, cilengitide treatment resulted in a decrease in proliferation, migration and invasion of MDA-MB-231 cells, as well as of osteoclast activity. In vivo, the development of bone metastasis in the hind leg of rats was not prevented by adjuvant cilengitide treatment, but cilengitide reduced the volumes of osteolytic lesions and respective soft tissue tumors of developing bone metastases as assessed with VCT and MRI, respectively. DCE-MRI revealed significant changes in the A and kep parameters including decreased relative blood volume and increased vessel permeability after cilengitide treatment indicating vessel remodeling. In conclusion, during early pathogenic processes of bone colonization, cilengitide treatment exerted effects on tumor cells, osteoclasts and vasculature reducing the skeletal lesion size of experimental skeletal metastases.