IGF-1对MC3T3-E1细胞凋亡及凋亡调控蛋白Bax、Bcl-2表达的影响

目的 探讨胰岛素样生长因子-1（IGF-1）对小鼠前成骨样MC3T3-E1细胞凋亡基因相关蛋白Bax／Bcl-2表达的影响。方法 MC3T3-E1细胞分组培养，应用4个浓度的IGF-1（1ng／mL、10ng／mL、30ng／mL、50ng／mL）干预24h。观察MC3T3-E1细胞动态生长状况：流式细胞技术检测细胞凋亡率；免疫组织化学法检测凋亡蛋白Pax／Bcl-2的表达水平。结果 与正常血清对照组相比，无血清对照组MC3T3-E1细胞凋亡率增加（P〈0．05）；与无血清组相比，IGF-1组MC3T3-E1细胞凋亡率降低（P〈0．05），Bax表达减弱（P〈0．05），Bcl-2表达增强（P〈0．05）；各浓度组间比较，（1～50）ng／mL浓度范围内MC3T3-E1细胞凋亡率随IGF-1浓度加大而逐渐降低（P〈0．05），Bax表达逐渐减弱（P〈0．05），50ng／mL浓度组Bcl-2表达明显增强（P〈0．01），Bcl-2／Bax灰度比与细胞凋亡率呈显著正相关（r=0.917，P〈0．01）。结论 一定浓度的IGF-1同时调节Bax和Bcl-2表达，抑制无血清培养诱导的细胞凋亡。并存在剂量依赖性效应。     

羟基喜树碱诱导口腔鳞癌细胞凋亡的作用机制探讨

目的探讨羟基喜树碱（HcPT）对人口腔鳞癌细胞株KB细胞的凋亡诱导作用及其机制。方法体外培养KB细胞，MTT试验检测HCPT的细胞毒性作用；Hoechst33258染色和流式细胞术对细胞凋亡进行定性和定量分析；蛋白印迹检测Caspase-3和Bcl-2蛋白表达情况。结果HCPT能诱导KB细胞凋亡，且具有剂量依赖关系；随凋亡率增高，Caspase-3蛋白表达显著增强，Bcl-2蛋白表达显著减弱（P均〈0．05）。结论HCPT可促进口腔鳞癌细胞凋亡，其可能机制是诱导Caspase-3蛋白表达和抑制Bcl-2蛋白表达。     

眼镜蛇毒细胞毒素13诱导人脐静脉内皮细胞凋亡及对Bcl-2家族基因表达的影响

目的 研究眼镜蛇毒细胞毒素13诱导人脐静脉内皮细胞凋亡作用及其对Bcl-2家族基因表达的影响.方法 CCK-8法测定细胞毒素13对人脐静脉内皮细胞增殖的影响;Annexin V-FITC/PI双染法观察细胞凋亡形态学改变;流式细胞术分析DNA倍体及细胞凋亡率;逆转录聚合酶链反应检测Bcl-2、Bax和Bcl-x_L基因表达的变化,Western blotting检测Bcl-2和Bax蛋白表达的变化.结果 细胞毒素13对人脐静脉内皮细胞增殖具有显著的抑制作用,并可诱导其发生凋亡,其抑制作用呈剂量依赖性.细胞毒素13可上调促凋亡蛋白Bax,而对抗凋亡蛋白Bcl-2和Bcl-x_L的表达无明显影响.结论 细胞毒素13可能通过上调Bax表达诱导细胞凋亡,抑制人脐静脉内皮细胞增殖.     

非小细胞肺癌Bcl-2基因蛋白表达及其与细胞凋亡和增殖的关系

目的探讨非小细胞肺癌Bcl-2蛋白表达与细胞凋亡和增殖的关系。方法采用SAB免疫组化法检测43例非小细胞肺癌及20例癌旁正常肺组织石蜡包埋标本Bcl-2蛋白及增殖细胞核抗原（PCNA）表达；用TUNEL法检测细胞凋亡。结果肺癌组织Bcl-2蛋白的表达显著高于癌旁肺组织，P〈0．05；肺癌组织中凋亡指数和增殖指数均明显高于癌旁正常肺组织，P〈0．01，Bcl-2表达阳性的肺癌组织细胞凋亡指数明显低于Bcl-2表达阴性组，P〈0．05；高细胞凋亡、增殖指数提示肺癌预后不良，P〈0．05。结论肺癌存在Bcl-2表达上调，Bcl-2异常表达在肺癌发生过程中可能起重要作用。     

苦参碱对白血病HL-60细胞增殖、凋亡及其Bcl-2mRNA、Survivin mRNA表达的影响

目的观察苦参碱在体外对急性早幼粒白血病HL-60细胞增殖抑制及诱导凋亡的作用,并探讨其可能的分子机制。方法体外培养HL-60细胞至对数生长期,分别以苦参碱（苦参碱组）、顺铂（顺铂组）和药物溶媒（对照组）处理,MTI＇法检测细胞生长抑制率、流式细胞仪检测细胞凋亡及周期变化,RT．PCR法检测Bcl-2mRNA、SurvivinmRNA表达。结果与对照组比较,苦参碱组细胞生长抑制率、凋亡率及G,期细胞比例增高,Bcl．2mR—NA、SurvivinmRNA表达均下调,且呈明显的浓度依赖性（P〈0．05或0．01）。结论苦参碱体外可抑制急性早幼粒白血病HL-60细胞增殖、诱导细胞凋亡,其作用机制可能与下调凋亡基因Bcl一2、Survivin表达有关。     

消瘤汤含药血清对人肝癌细胞HepG2凋亡相关因子表达的影响

[目的]观察消瘤汤含药血清对人肝癌细胞HepG2凋亡相关因子表达的影响,进一步证实该方对肿瘤细胞的抑制作用,并初步探讨其诱导肝癌细胞凋亡的作用机制。[方法]给予昆明种小鼠中药煎剂灌胃3d后,制备消瘤汤鼠含药血清,将其作用于HepG2细胞,用四氮唑盐法（MTT法）检测含药血清对HepG2细胞增殖的抑制作用,通过流式细胞技术测定肿瘤细胞的凋亡情况,应用免疫组化法检测半胱氨酸蛋白酸3（Caspase-3）、B细胞淋巴瘤2（Bcl-2）蛋白表达水平。[结果]消瘤汤鼠含药血清作用于HepG2细胞72h后,对肿瘤细胞生长有明显抑制作用。流式细胞仪检测可见含药血清组在细胞G1／G0期前出现明显的凋亡峰,即“亚二倍体峰”。凋亡率为22．3％,明显高于对照组的1．05％（P〈0．05）。免疫组化结果表明Caspase-3在含药血清干预后,表达明显增加,而Bcl-2在含药血清干预后,表达明显降低。[结论]消瘤汤可能通过激活Caspase-3及抑制Bcl-2的活性,从而诱导肝癌细胞凋亡,有效地抑制肝癌细胞生长,达到抗肿瘤的作用。     

牛蒡子苷元对肝癌SMMC-7721细胞增殖、凋亡的影响及机制探讨

目的观察牛蒡子苷元（ARG）对肝癌SMMC-7721细胞增殖、凋亡的影响,并探讨其机制。方法将不同浓度的ARG作用于SMMC-7721细胞,并设不加ARG对照组。MTT法测算细胞增殖抑制率、流式细胞术检测细胞周期及凋亡率,RT-PCR法检测细胞中的Bcl-2 mRNA。结果与对照组比较,随ARG浓度增加,SMMC-7721细胞增殖率逐渐降低（P均〈0.05）,G0/G1期细胞比例显著增加（P均〈0.05）,G2、M、S期细胞比例减少（P均〈0.05）;随ARG浓度增加、作用时间延长,SMMC-7721细胞凋亡率显著增加（P均〈0.05）,Bcl-2 mRNA表达量减少（P均〈0.05）。结论 ARG可明显抑制SMMC-7721细胞增殖并诱导其凋亡;可能与ARG下调细胞中Bcl-2基因的表达有关。     

小细胞肺癌阿霉素多药耐药细胞模型的建立及其与Bcl-2家族蛋白表达的关系

目的建立人小细胞肺癌（SCLC）阿霉素（ADM）多药耐药细胞系H446／ADM模型,分析凋亡相关基因Bcl-2家族在SCLC耐药性产生中的可能作用。方法采用ADM高浓度反复间歇诱导的方法,建立人SCLC的ADM多药耐药细胞系H446／ADM模型,流式细胞术分析细胞周期变化;MTT法分析细胞系的耐药谱。流式细胞术和Western blot法检测Bcl-2、Bcl-xL、Bak及Bax蛋白表达的变化。结果相对于亲代H446细胞,H446／ADM的生长速度减慢,细胞倍增时间延长,细胞周期分布G0／G1期细胞增加,G2／M期细胞减少;MTT法耐药谱分析示该细胞系对ADM的耐药倍数为33．09,此外,该细胞系对其他化疗药物如DNR、VCR、TAX、DDP、VP-16、MIT亦有交叉耐药。流式细胞术及Western blot法检测示H446／ADM细胞中Bcl-2和Bcl—xL表达明显高于H446,而Bak和Bax的表达水平明显降低（P〈0．05）。结论人SCLC耐药细胞系H446／ADM成功建立,有多药耐药性;Bcl-2家族蛋白表达的变化可能与耐药性产生有关。     

吲哚美辛对前列腺癌DU145细胞增殖与凋亡的影响及机制探讨

目的观察吲哚美辛对人激素非依赖性前腺癌细胞系DU145增殖和凋亡的影响，并探讨其作用机制。方法采用不同浓度的吲哚美辛处理DU145细胞。应用四甲基偶氮唑蓝（MTT）比色法检测并计算细胞增殖抑制率；流式细胞术检测细胞周期分布，并计算细胞凋亡率；采用酶联免疫吸附测定（ELISA）法测定细胞培养上清PGE2；应用RT-PCR法检测Bcl-2和Bax mRNA。结果吲哚美辛可明显抑制DU145细胞增殖（P〈0．05），并具有时间一剂量依赖性；经吲哚美辛作用后，S期细胞明显增多，G2/M期细胞减少，细胞出现凋亡峰；细胞上清中PGB量明显减少（P〈0．001）；Bcl-2 mRNA表达降低，BaxmRNA表达下降，Bcl-2／Bax下降（P〈0．05）。结论吲哚美辛对前列腺癌细胞DU145生长具有抑制作用，阻滞细胞向c2／M期转化，并促进其凋亡。其作用可能与抑制细胞PGE2释放、下调Bel-2／Bax有关。     

虫草菌丝对非酒精性脂肪肝病大鼠肝细胞凋亡的作用及其相关机制

目的（1）证实肝细胞凋亡的异常增多存在于非酒精性脂肪性肝病中。（2）观察虫草菌丝对肝细胞凋亡异常增多的影响，并探讨可能的分子机制。方法通过高脂饮食建立大鼠非酒精性脂肪性肝病（NAFLD）的模型，同时设立正常饮食对照组，病理对照组（NASH组），虫草菌丝干预组（CS组）。肝组织切片HE染色观察肝脏病理改变；检测肝组织超氧化物歧化酶（SOD）活性；TUNEL检测肝组织肝细胞凋亡情况；免疫组织化学染色观察肝组织Bax、Bcl-2、Caspase-3、NF-κB P65蛋白表达情况。结果（1）与正常对照组相比，病理对照组大鼠肝组织广泛弥漫肝细胞脂肪变性，炎性细胞浸润、坏死、局部有纤维组织增生；肝脏SOD活性显著降低（P〈0．01）；TUNEL法检测肝细胞凋亡显著增多（P〈0．01）；免疫组化染色显示Bax、Caspase-3蛋白表达增加（P〈0．01），而Bcl-2无显著变化（P〉0．05）；（2）与病理对照组相比，虫草菌丝组大鼠肝组织有广泛肝细胞脂肪变性，炎性细胞浸润，可见灶性及点状坏死，未见纤维组织增生；肝组织SOD活性高于病理对照组（P〈0．05）；TUNEL法检测凋亡的肝细胞显著减少（P〈0．01）；免疫组化染色显示Bax、Caspase-3蛋白表达也明显降低（分别为P〈0．05、P〈0．01），而Bcl-2、NF-κB P65蛋白表达增加（P〈0．01）。结论（1）NASH时肝细胞凋亡异常增多。（2）虫草菌丝可以通过增加超氧化物歧化酶（SOD）活性来减少活性氧含量，降低Bax表达，增加Bcl-2表达和活化NF-κB P65减轻NAFLD中肝细胞凋亡从而在一定程度上具有保护肝脏功能的作用，对延缓或阻止脂肪肝病变的进展起到一定的作用。     

Development of an in vivo model of human multiple myeloma bone disease

Osteolytic bone destruction and its complications, bone pain, pathologic fractures, and hypercalcemia, are a major source of morbidity and mortality in patients with multiple myeloma. The bone destruction in multiple myeloma is due to increased osteoclast (OCL) activity and decreased bone formation in areas of bone adjacent to myeloma cells. The mechanisms underlying osteolysis in multiple myeloma in vivo are unclear. We used a human plasma cell leukemia cell line, ARH-77, that has disseminated growth in mice with severe combined immunodeficiency (SCID) and expresses IgG kappa, as a model for human multiple myeloma, SCID mice were irradiated with 400 rads and mice were injected either with 10(6) ARH-77 cells intravenously (ARH-77 mice) or vehicle 24 hours after irradiation. Development of bone disease was assessed by blood ionized calcium levels, x-rays, and histology. All ARH-77, but none of control mice that survived irradiation, developed hind limb paralysis 28 to 35 days after injection and developed hypercalcemia (1.35 to 1.46 mmol/L) a mean of 5 days after becoming paraplegic. Lytic bone lesions were detected using x-rays in all the hypercalcemic mice examined. No lytic lesions or hypercalcemia developed in the controls. Controls or ARH-77 mice, after developing hypercalcemia, were then killed and bone marrow plasma from the long bones were obtained, concentrated, and assayed for bone-resorbing activity. Bone marrow plasma from ARH-77 mice induced significant bone resorption in the fetal rat long bone resorption assay when compared with controls (percentage of total 45Ca released = 35% +/- 4% v 11% +/- 1%). Histologic examination of tissues from the ARH-77 mice showed infiltration of myeloma cells in the liver and spleen and marked infiltration in vertebrae and long bones, with loss of bony trabeculae and increased OCL numbers. Interestingly, cultures of ARH-77 mouse bone marrow for early OCL precursors (colony-forming unit-granulocyte- macrophage [CFU-GM]) showed a threefold increase in CFU-GM from ARH-77 marrow versus controls (185 +/- 32 v 40 +/- 3 per 2 x 10(5) cell plated). Bone-resorbing human and murine cytokines such as interleukin- 6 (IL-6), IL-1 alpha or beta, TGF-alpha, lymphotoxin, and TNF alpha were not significantly increased in ARH-77 mouse sera or marrow plasma, compared with control mice, although ARH-77 cells produce IL-6 and lymphotoxin in vitro. Conditioned media from ARH-77 cells induced significant bone resorption in the fetal rat long bone resorption assay when compared with untreated media (percentage of total 45Ca released = 22% +/- 2% v 11% +/- 1%). This effect was not blocked by anti-IL-6 or antilymphotoxin (percentage of total 45Ca released = 19% +/- 1% and 22% +/- 1%, respectively). Thus, we have developed a model of human multiple myeloma bone disease that should be very useful to dissect the pathogenesis of the bone destruction in multiple myeloma.     

The Bisphosphonate Zoledronic Acid Induces Cytotoxicity in Human Myeloma Cell Lines with Enhancing Effects of Dexamethasone and Thalidomide

Bisphosphonates have recently been introduced in the therapeutic armamentarium for long-term treatment of patients with multiple myeloma. These pyrophosphate analogs not only reduce the occurrence of skeletal events but also provide clinical benefit to patients and improve the survival of some of them. The existence of these capabilities raises the possibility that these compounds may have a direct antiproliferative effect on tumor cells. To investigate whether these drugs exert a direct antitumor effect, we exposed human myeloma cell lines ARH-77 and RPMI-8226 to increasing concentrations of zoledronic acid (ZOL) in vitro. A concentration- but not time-dependent cytotoxic effect was detected with drug treatment of ARH-77 and RPMI-8226 cell lines (30% and 60% at 48 hours and 38% and 62% at 72 hours, respectively, for 50 microM of ZOL). Cytotoxicity was not due to ZOL-induced chelation of extracellular calcium as shown by control experiments with the calcium chelator ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid. Addition of the competitive inhibitor of the nitric oxide synthase N omega-nitro-L-arginine methyl ester did not modulate ZOL-induced cytotoxicity. However, a decrease in the number of apoptotic cells was detected when protein kinase C was inhibited by addition of staurosporine to ZOL-containing cultures. Cytotoxicity also was increased by addition of dexamethasone (Dex) and thalidomide (Thal) to ARH-77 and RPMI-8226 cultures. We demonstrated that exposing myeloma cell lines ARH-77 and RPMI-8226 to ZOL inhibits cell growth in a dose-dependent but not a time-dependent manner and that combination of Dex and Thal with ZOL induces apoptotic cell death, providing a rationale for potential applications in vivo.     

Syndecan-1 expression suppresses the level of myeloma matrix metalloproteinase-9

ARH-77 human myeloma cells invade into type I collagen gels but become non-invasive when engineered to express syndecan-1, a heparan sulphate proteoglycan that promotes cell adhesion to collagen. To determine if syndecan-1 expression influences the activity of proteases that may facilitate invasion, we analysed media harvested from syndecan-1 expressing and non-expressing cells. High levels of a 92 kD gelatinase accumulated in serum-free growth medium of both parental and control-transfected ARH-77, but much less 92 kD gelatinase accumulated in the medium of ARH-77 transfectants expressing syndecan-1. The gelatinase was identified as matrix metalloproteinase (MMP)-9 because its activity was immunoprecipitated with a MMP-9-specific monoclonal antibody. Gelatinase activity and Western blot analyses revealed 2-3-fold less MMP-9 in medium from syndecan-1 transfected cells than in medium from parental cells. Decreased MMP-9 was not due to increased association of MMP-9 with cells expressing syndecan-1. An inverse correlation between the syndecan 1 level and the level of MMP-9 accumulation in the media was observed using a panel of ARH-77 transfectants expressing syndecan-1. Investigation of six unrelated human myeloma cell lines confirmed that high gelatinase levels were recovered from conditioned media of those that did not express syndecan-1 (ARH-77, Mer and Col) and one line that expressed a low level of syndecan-1 (RPMI-8226), but low gelatinase levels were recovered from media of lines that expressed high levels of syndecan-1 (ARK and clone 2+). Therefore syndecan-1 may play a dual role in inhibiting the metastasis of tumour cells by promoting cell adhesion to the extracellular matrix and suppressing the proteolytic activity needed for invasion.     

Nur77 converts phenotype of Bcl-B, an antiapoptotic protein expressed in plasma cells and myeloma

Defects in apoptosis mechanisms play important roles in malignancy and autoimmunity. Orphan nuclear receptor Nur77/TR3 has been demonstrated to bind antiapoptotic protein Bcl-2 and convert it from a cytoprotective to a cytodestructive protein, representing a phenotypic conversion mechanism. Of the 6 antiapoptotic human Bcl-2 family members, we found that Nur77/TR3 binds strongest to Bcl-B, showing selective reactivity with Bcl-B, Bcl-2, and Bfl-1 but not Bcl-X(L), Mcl-1, or Bcl-W. Nur77 converts the phenotype of Bcl-B from antiapoptotic to proapoptotic. Bcl-B is prominently expressed in plasma cells and multiple myeloma. Endogenous Bcl-B associates with endogenous Nur77 in RPMI 8226 myeloma cells, where RNA interference experiments demonstrated dependence on Bcl-B for Nur77-induced apoptosis. Furthermore, a Nur77-mimicking peptide killed RPMI 8226 myeloma cells through a Bcl-B-dependent mechanism. Because Bcl-B is abundantly expressed in plasma cells and some myelomas, these findings raise the possibility of exploiting the Nur77/Bcl-B mechanism for apoptosis for eradication of autoimmune plasma cells or myeloma.     

Systemic therapy of myeloma xenografts by an attenuated measles virus

Conditionally replicating viruses are promising agents for the treatment of malignancy. Here it is shown that the live attenuated Edmonston-B vaccine strain of measles virus (MV-Edm) replicates selectively in human myeloma cells and has potent antitumor activity. In vitro, replication of MV-Edm was restricted in phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PBLs) but proceeded efficiently in a panel of 6 myeloma cell lines-ARH-77, RPMI 8226, JJN-3, MM1, KAS-6/1, and KMS-11-and in primary myeloma cells isolated by CD138 sorting from the bone marrow aspirates of 6 patients. MV-Edm infection induced potent cytopathic effects in these myeloma cells, resulting in the formation of multinucleated syncytia that eventually became nonviable. In contrast, syncytial formation in PHA-stimulated PBLs was minimal after MV-Edm infection. In vivo, MV-Edm was antitumorigenic and inhibited the establishment of myeloma cells as xenografts in immunocompromised mice. When injected directly into ARH-77 myeloma xenografts in the mice, MV-Edm caused complete regression of these xenografts. MV-Edm administered intravenously into the tail veins of mice also showed significant antineoplastic activity against established RPMI 8226 and ARH-77 xenografts. In particular, the ARH-77 myeloma xenografts were exquisitely sensitive to MV-Edm therapy, and tumors in all mice regressed completely. In light of its selectivity for myeloma cells and its potent antineoplastic activity against myeloma xenografts in vivo, MV-Edm merits further development for the treatment of multiple myeloma.     

Native osteoprotegerin gene transfer inhibits the development of murine osteolytic bone disease induced by tumor xenografts

OBJECTIVE: Multiple myeloma is a plasma cell malignancy characterized by the development of osteolytic lesions leading to bone pain, pathologic fractures, and hypercalcemia. Osteoprotegerin (OPG) is a potent inhibitor of osteoclast differentiation and activation, but is limited as a therapeutic agent due to its short circulating half-life. In order to overcome these limitations, the therapeutic effects of native OPG gene transfer are examined. MATERIALS AND METHODS: We used replication-incompetent lentiviral vectors to transfer the unmodified, native human OPG gene ex vivo into human ARH-77 cells injected into severe combined immunodeficient (SCID) mice, to determine gene transfer efficiency as well as the impact on disease progression in this in vivo model. RESULTS: We can efficiently transfer and express either the LacZ marker gene or the native human OPG gene into human ARH-77 cells. Moreover, transfer of the OPG gene into ARH-77 cells reduces the development of osteolytic bony lesions when these cells are injected into SCID mice, compared to mice injected with either unmodified ARH-77 cells or ARH-77 cells transduced with the OPG gene in the antisense orientation. This therapeutic effect was manifested as a reduction in vertebral compression deformities and in the number and size of long-bone osteolytic lesions on skeletal radiographs, as well as a decrease in osteoclast surface on histologic analysis. CONCLUSIONS: A lentiviral vector can efficiently transfer the native human OPG gene to myeloma cells ex vivo and inhibit myeloma-induced bone destruction, thereby suggesting a therapeutic potential for unmodified, native OPG gene transfer for osteoclast-dependent skeletal disorders.     

Ibandronate decreases bone disease development and osteoclast stimulatory activity in an in vivo model of human myeloma

The benefits of bisphosphonate therapy for multiple myeloma bone disease have been clearly documented. However, the effects of bisphosphonates on the osteoclast stimulatory activity (OSA) that is present in the marrow of patients with multiple myeloma, even before the bone disease is detectable, are unknown. Therefore, we examined the effects of ibandronate (IB) treatment prior to the development of bone disease in a murine model of human myeloma.Sublethally irradiated severe combined immunodeficient (SCID) mice were transplanted with ARH-77 cells on day 0. These ARH-77 mice were treated daily with subcutaneous injections of IB started before or at different times after tumor injection as follows: group 1 was started on day -7; group 2 on day 0; group 3 on day +7; group 4 on day +14 after IB administration; and group 5 (control) received no IB. Mice were sacrificed after they developed paraplegia.The onset of paraplegia was delayed in group 1 vs all other groups (mean day 27 vs day 32; p = 0.0098). The number of lytic lesions and the bone surface area of resorption (mm(2)) were significantly decreased in groups 1, 2, and 3, which were treated early with IB, when compared with groups 4 and 5 (p = 0.003 and 0.002, respectively). OSA, as measured by the capacity of bone marrow plasma from ARH-77 mice to induce osteoclast (OCL) formation in human bone marrow cultures, was decreased proportionally to the length of IB treatment. Group 1 had the lowest OSA compared with the other groups (p = 0.003). However, all mice eventually developed paraplegia, and at time of sacrifice, tumor burden was not grossly different among the groups. Interestingly, macroscopic abdominal tumors were more frequent in mice treated with IB.These data demonstrate that early treatment of ARH-77 mice with IB prior to development of myeloma bone disease decreases OSA and possibly retards the development of lytic lesions, but not eventual tumor burden.     

Interleukin-6 inhibits the chemotaxis of human malignant plasma cell lines

The chemotaxis of human malignant plasma cells is promoted by two extracellular matrix proteins (ECMs): fibronectin (FN) and laminin (LN). We examined the effect of the supernatant from a bone marrow stroma cell line, KM-101, on the chemotaxis of human malignant plasma cell lines to assess the chemotaxis-regulatory roles of the bone marrow microenvironment. Five human malignant plasma cell lines, FR4ds, OPM-1ds, U266/B1, RPMI-8226 and ARH-77 showed different profiles of the expression of β1 integrins of FN and LN receptors. FR4ds, OPM-1ds and U266/B1 cells showed chemotaxis promoted by FN (Ch^FN) and LN (Ch^LN). ARH-77 cells showed Ch^FN but not Ch^LN. RPMI-8226 cells did not show either Ch^FN or Ch^LN. The supernatant from KM-101 cells inhibited the chemotaxis of each of these cell lines regardless of whether the chemotaxis was promoted by FN or LN. Among the cytokines produced by KM-101 cells, it was postulated that IL-6 mediated this inhibitory effect because anti-IL-6 monoclonal antibody (MoAb) and anti-IL-6 receptor MoAb significantly reversed the inhibition. Recombinant IL-6 (rIL-6) also exhibited a similar inhibitory effect. Because anti-gp130 MoAb significantly reversed the chemotaxis inhibitory effect of rIL-6, the inhibitory signal is probably transduced via the signal transducing receptor component, gp130. The chemotaxis-regulatory effect is another previously unrecognized function of this pleiotropic cytokine, IL-6. High levels of IL-6 in the bone marrow microenvironment of patients with multiple myeloma appears to be favourable for the localization of myeloma cells there.