Synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid induces growth arrest in HER2-overexpressing breast cancer cells

HER2 overexpression is one of the most recognizable molecular alterations in breast tumors known to be associated with a poor prognosis. In the study described here, we explored the effect of HER2 overexpression on the sensitivity of breast cancer cells to the growth-inhibitory effects of 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO), a synthetic triterpenoid, both in vitro and in vivo in a xenograft model of breast cancer. Both cell growth and colony formation in the soft agar assay, a hallmark of the transformation phenotype, were preferentially suppressed in HER2-overexpressing cell lines at low concentrations of CDDO, whereas growth-inhibitory effects at high concentrations did not correlate with the expression level of HER2. CDDO dose-dependently inhibited phosphorylation of HER2 in HER2-overexpressing cells and diminished HER2 kinase activity in vitro. CDDO induced the transactivation of the nuclear receptor peroxisome proliferator-activated receptor-gamma in both vector control and HER2-transfected MCF7 cells. Dose-response studies showed that the growth inhibition seen at lower concentrations of CDDO correlated with induction of the tumor suppressor gene caveolin-1, which is known to inhibit breast cancer cell growth. CDDO also reduced cyclin D1 mRNA and protein expression. In vivo studies with liposomally encapsulated CDDO showed complete abrogation of the growth of the highly tumorigenic MCF7/HER2 cells in a xenograft model of breast cancer. These findings provide the first in vitro and in vivo evidence that CDDO effectively inhibits HER2 tyrosine kinase activity and potently suppresses the growth of HER2-overexpressing breast cancer cells and suggest that CDDO has a therapeutic potential in advanced breast cancer.     

Identification of a novel synthetic triterpenoid,methyl-2-cyano-3,12-dioxooleana-1,9-dien-28-oate,that potently induces caspase-mediated apoptosis in human lung cancer cells

Lung cancer continues to be the leading cause of cancer-related death in the United States. Therefore, new agents targeting prevention and treatment of lung cancer are urgently needed. In the present study, we demonstrate that a novel synthetic triterpenoid methyl-2-cyano-3,12-dioxooleana-1,9-dien-28-oate (CDDO-Me) is a potent inducer of apoptosis in human non-small cell lung carcinoma (NSCLC) cells. The concentrations required for a 50% decrease in cell survival (IC50) ranged from 0.1 to 0.3 microM. CDDO-Me induced rapid apoptosis and triggered a series of effects associated with apoptosis including a rapid release of cytochrome c from mitochondria, activation of procaspase-9, -7, -6, and -3, and cleavage of poly(ADP-ribose) polymerase and lamin A/C. Moreover, the caspase-3 inhibitor Z-DEVD-FMK and the pan caspase inhibitor Z-VAD-FMK suppressed CDDO-Me-induced apoptosis. These results indicate that CDDO-Me induced apoptosis in human NSCLC cells via a cytochrome c-triggered caspase activation pathway. CDDO-Me did not alter the level of Bcl-2 and Bcl-xL proteins, and no correlation was found between cell sensitivity to CDDO-Me and basal Bcl-2 expression level. Furthermore, overexpression of Bcl-2 did not protect cells from CDDO-Me-induced apoptosis. These results suggest that CDDO-Me induces apoptosis in NSCLC cells irrespective of Bcl-2 expression level. In addition, no correlation was found between cell sensitivity to CDDO-Me and p53 status, suggesting that CDDO-Me induce a p53-independent apoptosis. Our results demonstrate that CDDO-Me may be a good candidate for additional evaluation as a potential therapeutic agent for human lung cancers and possibly other types of cancer.     

Inhibition of mitochondrial metabolism by methyl-2-cyano-3,12-dioxooleana-1,9-diene-28-oate induces apoptotic or autophagic cell death in chronic myeloid leukemia cells

The initial success of the first synthetic bcr-abl kinase inhibitor imatinib has been dampened by the emergence of imatinib-resistant disease in blast crisis chronic myeloid leukemia. Here, we report that the novel triterpenoid methyl-2-cyano-3,12-dioxooleana-1,9-diene-28-oate (CDDO-Me) potently induced cytotoxicity in imatinib-resistant KBM5 cells expressing the T315I mutation of bcr-abl (24-h EC50, 540 nmol/L). In long-term culture, CDDO-Me abrogated the growth of human parental KBM5 and KBM5-STI cells with 96-h IC50 of 205 and 221 nmol/L, respectively. In addition, CDDO-Me rapidly decreased the viability of murine lymphoid Ba/F3 cells expressing wild-type p210 as well as the imatinib-resistant E255K and T315I mutations of bcr-abl. The low-dose effects of CDDO-Me are associated with inhibition of mitochondrial oxygen consumption, whereas the cytotoxic effects appear to be mediated by a rapid and selective depletion of mitochondrial glutathione that accompanies the increased generation of reactive oxygen species and mitochondrial dysfunction. Interestingly, the mitochondriotoxic effects of CDDO-Me are followed by the rapid autophagocytosis of intracellular organelles or the externalization of phosphatidylserine in different cell types. We conclude that alterations in mitochondrial function by CDDO-Me can result in autophagy or apoptosis of chronic myeloid leukemia cells regardless of the mutational status of bcr-abl. CDDO-Me is in clinical trials and shows signs of clinical activity, with minimal side effects and complete lack of cardiotoxicity. Studies in leukemias are in preparation.     

2-甲氧基雌二醇联合硼替佐米对多发性骨髓瘤细胞凋亡的影响

目的 探讨2-甲氧基雌二醇(2-ME2)联合硼替佐米的抗多发性骨髓瘤(MM)效应及与聚集小体(aggresome)形成之间的相关性.方法 以MM细胞系RPMI 8226、NCI-H929、U266、SKO-007细胞作为研究对象,采用硼替佐米单药或联合2-ME2处理,通过等效应线图法分析两者是否具有抗MM协同效应;通过免疫荧光技术在同一组细胞群中研究聚集小体阳性和阴性细胞的凋亡情况.结果 ①硼替佐米呈浓度和时间依赖性地显著提高聚集小体阳性细胞比例,且聚集小体几乎全部出现于非凋亡细胞中.②等效应线图法分析显示一定浓度范围的硼替佐米与2-ME2联合具有显著的协同作用.③硼替佐米与2-ME2联合应用后聚集小体阴性的凋亡细胞显著增多而聚集小体阳性的非凋亡细胞明显减少.在RPMI 8226及U266细胞中,硼替佐米单药与联合用药组相比,聚集小体阴性的凋亡细胞分别由(14.5±2.6)%及(20.1±2.9)%增加至(80.7±6.9)%及(71.6±6.2)%;聚集小体阳性的非凋亡细胞分别由(75.3±5.7)%及(69.1±8.6)%减少到(13.8±3.8)%及(19.5±4.2)%.结论 硼替佐米诱导生成的聚集小体对MM细胞具有保护作用;2-ME2通过抑制聚集小体途径可以显著增强硼替佐米的抗MM效应.     

SIRT2 and SIRT3 expression correlates with redox imbalance and advanced clinical stage in patients with multiple myeloma

ObjectivesSirtuins comprise seven family elements (SIRT1-7) involved in various cell signalling pathways comprising cancer inhibition and tumorigenesis. The present study aims to evaluate SIRT2 and SIRT3 gene expression and potential redox reactions in patients with multiple myeloma (MM) at onset and its correlation with disease status, extent and presence of organ damage secondary to myeloma.Design & MethodsTotal RNA was extracted from 17 MM patients and 10 controls to assess gene expression using real-time PCR. The NAD+/NADH ratio as well as the levels of glutathione peroxidase (GPx) and hydrogen peroxide (HP) in peripheral blood mononuclear cells (PBMCs) were determined using established biochemical assays.ResultsSIRT2 and SIRT3 expression is reduced in MM patients compared to healthy controls. Correlational analysis demonstrated that SIRT2 reduction is associated with advanced clinical stage and with more advanced bone lesions than in the remaining patients. SIRT3 expression is correlated with lytic bone lesions. Biochemical analysis indicated an imbalance of oxidative stress biomarkers with low concentrations of the antioxidant enzyme GPx, low amounts of NAD + and higher concentrations of pro-oxidant enzyme HP in PBMCs of MM patients compared to controls. Moreover, MM patients with bone lesions had lower concentrations of NAD + and GPx in PBMCs than patients without signs of bone disease. In addition, MM patients had higher quantities of intracellular HP than controls.ConclusionsOur results demonstrate that SIRT2 and SIRT3 are downregulated in MM and that lower concentrations correlate with an advanced stage of disease and redox imbalance. We conclude that SIRT2 and SIRT3 together with oxidative stress biomarkers, may be useful for improved risk stratification of MM patients.     

雷公藤内酯醇对硼替佐米诱导多发性骨髓瘤细胞凋亡的影响

本研究旨在探讨雷公藤内酯醇对硼替佐米诱导骨髓瘤细胞株NCI-H929(H929)凋亡的影响。通过MTT法检测不同浓度的雷公藤内酯和硼替佐米单用及联用对H929细胞的增殖抑制作用;采用Annexin Ⅴ-FITC/PI双染流式细胞术检测细胞凋亡率。结果表明:雷公藤内酯醇(10-100 ng/ml)和硼替佐米(10-100 nmol/L)单用和联用均可抑制H929细胞增殖,呈浓度依赖性,雷公藤内酯醇和硼替佐米联用组的细胞凋亡率明显高于单用硼替佐米组。经非抑制浓度的雷公藤内酯醇(10 ng/ml)联合硼替佐米(40 nmol/L)处理H929细胞24 h后的凋亡率明显高于单用硼替佐米组(P<0.05)。结论:雷公藤内酯醇能够显著增强硼替佐米对多发性骨髓瘤细胞的促凋亡活性。     

Dehydroxymethylepoxyquinomicin, a novel nuclear factor-kappaB inhibitor, induces apoptosis in multiple myeloma cells in an IkappaBalpha-independent manner

Nuclear factor-kappaB (NF-kappaB) is constitutively activated in multiple myeloma cells. Several proteasome inhibitors have been shown to be effective against multiple myeloma and may act by inhibiting degradation of IkappaBalpha. Here, we examined the biological effects of a new type of NF-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), which is reported to directly inhibit the cytoplasm-to-nucleus translocation of NF-kappaB. A multiple myeloma cell line, 12PE, which is defective for IkappaBalpha protein, was utilized to determine if IkappaBalpha is concerned with the action of DHMEQ. Meanwhile, U266 was used as a multiple myeloma cell line with normal IkappaBalpha. A proteasome inhibitor, gliotoxin, which is an inhibitor of degradation of phosphorylated IkappaBalpha, failed to inhibit translocation of NF-kappaB in 12PE. In contrast, DHMEQ equally inhibited translocation of NF-kappaB to the nucleus and induced apoptosis to both multiple myeloma cell lines, suggesting that apoptosis resulting from DHMEQ is IkappaBalpha independent. DHMEQ also induced apoptosis in freshly isolated multiple myeloma cells. After DHMEQ treatment, cleavage of caspase-3 and down-regulation of cyclin D1 were observed in both cell lines. In addition, administration of DHMEQ resulted in a significant reduction in tumor volume in a plasmacytoma mice model compared with control mice. Our results show that DHMEQ could potentially be a new type of molecular target agent for multiple myeloma.     

氟达拉滨诱导多发性骨髓瘤细胞凋亡及其基因表达分析

目的 探讨氟达拉滨诱导多发性骨髓瘤(MM)细胞凋亡及其分子机制.方法 用MTT法检测氟达拉滨对MM细胞的生长抑制作用;用流式细胞术检测细胞凋亡;Western blot法分析凋亡蛋白表达;采用细胞凋亡基因芯片技术检测并分析对照组与氟达拉滨处理组间的基因表达差异.结果 氟达拉滨显著抑制RPMI8226和KM3细胞生长,呈时间和剂量依赖性.24 h半数生长抑制值(IC50)分别为2.13μg/ml和0.36 μg/ml.流式细胞术分析显示,氟达拉滨作用24 h后MM细胞凋亡呈剂量依赖性,同时伴有caspase-3和PRAP激活,具有典型的细胞凋亡生物学特征.在97个凋亡相关基因中,筛选出25个差异表达基因.氟达拉滨处理组与对照组比较,表达上调的基因有13个,主要涉及Bcl-2家族促凋亡基因、肿瘤坏死因子及其受体超家族基因,以及胱天蛋白酶募集结构域家族.表达下调的基因有12个,主要涉及Bcl-2家族抗凋亡基因、肿瘤坏死因子超家族及其受体相关因子基因,以及凋亡抑制蛋白家族.结论 氟达拉滨显著抑制MM细胞生长,诱导细胞凋亡;其作用机制涉及多个凋亡相关基因表达改变.     

脂肪酸合成酶抑制剂抑制人多发性骨髓瘤细胞增殖及诱导其凋亡的研究

目的 明确脂肪酸合成酶（FAS）在人多发性骨髓瘤（MM）细胞中的高表达；探讨FAS抑制剂抑制MM细胞增殖及诱导其凋亡的机制。方法 通过RT-PCR方法检测FAS在MM细胞系U266、RPMI8226细胞中的表达；以MM细胞系U266细胞为模型，MTT法观察FAS抑制剂浅蓝菌素（cerulenin）对U266细胞增殖抑制率；以流式细胞术检测经cerulenin处理后U266细胞Annexin V的表达及细胞周期变化。结果 MM细胞系U266、RPMI8226细胞均有FAS mRNA的高表达，而健康献血员外周血单个核细胞（PBMNC）中不表达FAS mRNA；cerulenin对U266细胞增殖有显著的抑制作用，并呈剂量-效应相关；20μg／ml的cerulenin作用于U266细胞12h，细胞早期凋亡率为56．9％，24h细胞早期凋亡率为69．3％，而对照组分别为4．3％和1．8％（P＜0．01）；细胞周期DNA分析发现，20μg／mlcerulenin作用于U266细胞12h，S期细胞从对照组的9．7％上升至20．3％，作用24h，S期细胞上升为29．8％。结论 FAS在MM细胞中高表达；FAS抑制剂可抑制U266细胞的增殖；DNA合成阻止在S期，其抑制增殖的作用可能是通过促进U266细胞早期凋亡；FAS可能是一个潜在的抗MM的靶位。     

藤黄酸诱导骨髓瘤U266细胞凋亡及机制研究

目的探讨藤黄酸对人多发性骨髓瘤U266细胞凋亡的影响及机制。方法不同浓度藤黄酸处理U266细胞,四甲基偶氮唑盐(MTT)法检测对细胞增殖的影响,AnnexinⅤ/PI双染法检测细胞的凋亡,JC-1染色法检测线粒体跨膜电位水平,流式细胞仪检测荧光素激活的Caspase3、Caspase8、Caspase9阳性细胞水平。结果藤黄酸呈浓度依赖性抑制U266细胞的生长,藤黄酸>0.5μg/ml才出现较明显的诱导凋亡的能力,藤黄酸降低U266细胞线粒体跨膜电位水平。藤黄酸作用U266细胞24h和48h时激活的Caspase3、Caspase8、Caspase9阳性细胞比例分别上升24.9%、31.7%、32.4%和57.0%、64.5%、63.5%。结论藤黄酸可抑制U266细胞的生长,机制与诱导U266细胞凋亡有关,线粒体跨膜电位途径和胞浆激活途径参与了凋亡的发生。     

间充质干细胞对多发性骨髓瘤细胞生长及硼替佐米诱导其凋亡的影响研究

目的 探讨间充质干细胞在多发性骨髓瘤细胞生长以及硼替佐米诱导骨髓瘤细胞凋亡中的作用.方法 取15例临床确诊的多发性骨髓瘤(MM)患者以及3名正常供者的骨髓标本,分离其间充质干细胞(MM-BMSC和ND-BMSC);测定细胞生长曲线、免疫表型和细胞因子分泌水平.将骨髓瘤细胞(NCI-H929)与BMSC细胞共培养,并加入蛋白酶体抑制剂硼替佐米,观察BMSC对NCI-H929细胞生长增殖的影响;进一步通过Annexin V-FITC/PI双染法流式细胞术(FCM)检测BMSC对硼替佐米诱导NCI-H929细胞凋亡的影响.结果 成功分离得到MM患者以及正常供者骨髓间充质干细胞,FCM检测显示两者均高表达CD73和CD105(＞95%),表达CD44和CD29,不表达CD31、CD34、CD45和HLA-DR(＜1%)等表面分子.生长曲线测定显示MM-BMSC增殖较为缓慢,倍增时间(82 h)较ND-BMSC(62 h)略有延长(P＜0.05).与ND-BMSC比较,MM-BMSC分泌高水平的细胞因子IL-6和VEGF,分别为(188.8±9.4)pg/ml对(115.0±15.1)pg/ml和(1497.2±39.7)pg/ml对(1329.0±21.1)pg/ml.将BMSC与骨髓瘤细胞NCI-H929共培养,MM-BMSC可促进骨髓瘤细胞的生存,降低NCI-H929细胞对硼替佐米的敏感性,明显抑制硼替佐米诱导的瘤细胞凋亡.结论 MM-BMSC可促进骨髓瘤细胞的生长,明显减少蛋白酶体抑制剂硼替佐米诱导的细胞凋亡.     

骨髓增生异常综合征造血细胞凋亡的研究进展

骨髓增生异常综合征（ＭＤＳ）是一组恶性克隆性造血干细胞疾病,以血细胞的质、量异常,骨髓病态造血及高风险发展为急性白血病为主要特征。大部分ＭＤＳ患者在髓内造血活跃的同时,却伴有外周血细胞减少。这一矛盾现象被称为ＭＤＳ骨髓和“无效造血”。不少研究表明,过...     

IMP dehydrogenase inhibitor mycophenolate mofetil induces caspase-dependent apoptosis and cell cycle inhibition in multiple myeloma cells

Multiple myeloma is an incurable disease for the majority of patients, therefore requiring new biological targeted therapies. In primary myeloma cells, IMP dehydrogenase (IMPDH) was shown to be consistently overexpressed. We therefore tested the IMPDH inhibitor mycophenolate mofetil (MMF) currently available as a clinical therapeutic agent for its antimyeloma activity in vitro. MMF depleted intracellular guanosine 5'-triphosphate (GTP) levels in myeloma cells. We showed apoptosis induction in myeloma cell lines and primary myeloma cells between 1 and 5 mumol/L MMF. MMF was also cytotoxic at this concentration in dexamethasone-resistant and Mcl-1-overexpressed myeloma cell lines shown by the tetrazolium salt XTT assay along with cell survival measured by a modified flow cytometric assay. Apoptosis was not inhibited by the presence of an antioxidant, suggesting that MMF-induced apoptosis is less likely to be associated with reactive oxygen species. However, apoptosis was abrogated by exogenously added guanosine, which activates an alternative pathway for GTP formation, implicating that this effect is directly mediated by IMPDH inhibition. MMF-induced G1-S phase cell cycle arrest and its apoptosis induction mechanism were associated with a caspase-dependent pathway as shown by alteration of mitochondrial membrane potential and cytochrome c release followed by activation of the caspases. MMF-induced apoptosis was also inhibited by a pan-caspase inhibitor Z-VAD-fmk. MMF-treated myeloma cells showed an up-regulation of Bak, which most likely together with Bax resulted in the release of cytochrome c. In summary, MMF attenuates G1-S phase cell cycle progression and activates the pathway of mitochondrial dysfunction, leading to cytochrome c release followed by activation of caspases.     

尿多酸肽通过调节caspase家族诱导多发性骨髓瘤细胞U266凋亡的实验研究

目的探讨尿多酸肽抑制多发性骨髓瘤（MM）细胞株U266增值及其机制。 方法采用四甲基偶氮唑（MTT）比色法计算不同尿多酸肽浓度（1.0、2.0、3.0、4.0、5.0 mg/g）对U266细胞生长的抑制率,Hoechst33258染色观察尿多酸肽作用后的细胞凋亡情况,Annexin-V/碘化丙啶（PI）检测尿多酸肽作用6、12、24 h后与对照组细胞（加细胞未加药物）的细胞凋亡率。使用Western-blotting法检测caspase 8、caspase 3及其激活物在U266细胞株经尿多酸肽（4 mg/g）作用6、12、24 h后的表达改变。 结果随着尿多酸肽浓度提高,U266细胞抑制率显著上升（F= 17.276,P< 0.001）。经尿多酸肽作用后,Hoechst33258荧光染色提示细胞核浓集及出现凋亡小体。Annexin-V/PI分析显示,尿多酸肽处理6、12、24 h后细胞凋亡率显著高于对照组细胞[（5.53 ± 0.28）%、（9.43 ± 1.78）%、（21.50 ± 2.45）%、（3.03 ± 0.11）%,F= 12.242,P<0.001]。同时,随着尿多酸肽作用时间延长,pro-caspase 8、pro-caspase 3表达明显下降（F= 18.241,P<0.001;F= 4.924,P= 0.005）,而active-caspase 8、active-caspase 3表达明显上升（F= 22.322,P<0.001;F= 6.213,P= 0.002）。 结论尿多酸肽可抑制U266细胞增殖,且可能通过caspase凋亡途径在其中起主要作用。     

Caspase-2 functions upstream of mitochondria in endoplasmic reticulum stress-induced apoptosis by bortezomib in human myeloma cells

Multiple myeloma is an incurable plasma cell malignancy. The 26S proteasome inhibitor, bortezomib, selectively induces apoptosis in multiple myeloma cells; however, the mechanism by which this compound acts remains unknown. Here, we, using immunoblotting analysis, observed that the expression of BiP, CHOP, and XBP-1 is up-regulated in bortezomib-induced apoptosis in human multiple myeloma cell lines NCI-H929 and RPMI-8226/S, strongly suggesting that endoplasmic reticulum (ER) stress response or the unfolded protein response (UPR), a signaling pathway activated by the accumulation of unfolded proteins within ER, is initiated. In the meantime, we also showed that bortezomib inhibited classic ER stressor brefeldin A-induced up-regulation of prosurvival UPR components BiP and XBP-1, resulting in increased induction of apoptosis in multiple myeloma cell lines, raising the possibility that bortezomib induces apoptosis of multiple myeloma cells by means of evoking the severe ER stress but disrupting the prosurvival UPR required. Using caspase inhibitors and a RNA interference approach, we finally confirmed that bortezomib-triggered apoptosis in multiple myeloma cells is dependent on caspase-2 activation, which is associated with ER stress and required for release of cytochrome c, breakdown of mitochondrial transmembrane potential, and its downstream caspase-9 activation. Taken together, these data strongly suggest that caspase-2 can serve as a proximal caspase that functions upstream of mitochondrial signaling during ER stress-induced apoptosis by bortezomib in multiple myeloma cells.     

骨髓瘤细胞和骨髓基质细胞均参与多发性骨髓瘤白细胞介素6过度分泌

目的：探讨白细胞介素６（ＩＬ６）在多发性骨髓瘤（ＭＭ）中过度表达的机制。方法：采用多聚甲醛分别固定骨髓瘤细胞ＫＭ３和骨髓基质细胞，再将其置于同一体系中共同培养，用Ｂ９细胞增殖试验测量培养上清中ＩＬ６活性。结果：骨髓基质细胞及骨髓瘤细胞均能自发分泌ＩＬ６，两种细胞经固定后几乎均不能分泌ＩＬ６。固定的骨髓瘤细胞与未经固定的骨髓基质细胞共培养后，可使共培养上清中的ＩＬ６活性明显增加，同时固定后的骨髓基质细胞与未固定的骨髓瘤细胞共培养后亦可使后者分泌ＩＬ６增加，其中ＭＭ患者的骨髓基质细胞较正常对照组骨髓基质细胞与骨髓瘤细胞共培养后上清中ＩＬ６活性增加更明显（Ｐ均＜０．０１）。结论：ＭＭ患者ＩＬ６过度产生的机制存在二相性，即骨髓瘤细胞和骨髓基质细胞均可过度表达ＩＬ６，参与ＭＭ的发病。     

骨髓瘤细胞和骨髓基质细胞均参与多发性骨髓瘤白细胞介素6过？…

目的：探讨白细胞介素６（ＩＬ－６）在多发性骨髓瘤（ＭＭ）中过度表达的机制。方法：采用多聚甲醛分别固定骨髓瘤细胞ＫＭ３和骨髓基质细胞，再将其置于同一体系中共同培养，用Ｂ９细胞增殖试验测量培养上清中ＩＬ－６活性。结果：骨髓基质细胞及骨髓瘤细胞均能自发分泌ＩＬ－６，两种细胞经固定后几乎均不能分泌ＩＬ－６。固定的骨髓瘤细胞与未经固定的骨髓基质细胞共培养后，可使共培养上清中的ＩＬ－６活性明显增加，同时固定后