Pramipexole protects against H2O2-induced PC12 cell death

Pramipexole, a novel non-ergot dopamine (DA) agonist, has been successfully applied to the treatment of Parkinson’s disease (PD). Although the specific cause of PD remains unknown, recent studies have provided evidence that oxidative stress plays a role in the parthenogenesis of the disease. In the present study, we examined the effect of pramipexole on hydrogen peroxide (H₂O₂, 100 μM)-induced PC12 cell death, and the intracellular mechanism of this effect. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay revealed that pretreatment of PC12 cells with pramipexole (1–100 μM) resulted in significant protection against H₂O₂-induced cell death in a concentration-dependent manner. The protective effect of pramipexole was not affected by pretreatment with the DA receptor antagonists sulpiride, spiperone or domperidone, suggesting that the effect of pramipexole is not mediated by DA receptors. In PC12 cells, pramipexole inhibited H₂O₂-induced lactate dehydrogenase (LDH) leakage, as well as H₂O₂-induced cytochrome c release and caspase-3 activation with the resultant apoptosis. It was also observed in PC12 cells that H₂O₂ stimulated phosphorylation of mitogen-activated protein (MAP) kinases, i.e., extracellular signal-regulated kinase1/2 (ERK1/2), c-Jun NH₂-terminal kinase (JNK) and p38 MAP kinase. Pramipexole inhibited H₂O₂-induced JNK and p38 MAP kinase, but not ERK1/2 phosphorylation. Furthermore, in these cells experiments with a fluorescent probe, 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid, revealed that pramipexole, the JNK inhibitor SP600125 and the p38 MAP kinase inhibitor SB203580 inhibited the generation of H₂O₂-induced reactive oxygen species. Caspase inhibitors Z-DEVD-FMK and Z-IETD-FMK, as well as SP600125 and SB203580, inhibited H₂O₂-induced PC12 cell death to a similar extent as pramipexole. These results suggest that pramipexole exerts a protective effect against oxidative stress-induced PC12 cell death in part through an inhibition of JNK and p38 MAP kinase.     

Reduction by NG-nitro-L-arginine of H2O2-induced endothelial cell injury.

1. The effects of three analogues of NG-nitro-L-arginine (L-NOARG) and NG-monomethyl-L-arginine (L-NMMA), inhibitors of nitric oxide (NO) synthase, on hydrogen peroxide (H2O2)-induced endothelial cell injury were studied. 2. Endothelial cell injury was assessed by measuring the release of intracellular lactate dehydrogenase (LDH) and 51Cr. 3. Addition of H2O2 (250-1,000 microM) to endothelial cells induced the release of LDH dose-dependently. The release of LDH was reduced by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 10(-4)-4 x 10(-3) M), L-NOARG (10(-4)-4 x 10(-3) M) and NG-nitro-L-arginine benzyl ester (L-NABE, 10(-4)-4 x 10(-3) M), inhibitors of NO synthase. 4. L-NOARG analogues also reduced H2O2-induced 51Cr release from endothelial cells, while L-NMMA had no effect. 5. The protective effect of L-NAME was not reversed by addition of L-arginine (L-Arg, 1-10 mM). 6. Both L-NAME and L-NMMA completely inhibited L-Arg metabolism to L-citrulline coupled with NO synthesis. 7. These findings suggest that L-NOARG analogues but not L-NMMA reduced H2O2-induced endothelial cell injury, and that these effects may not be related to inhibition of NO production.     

Cyclooxygenase-independent inhibition of smooth muscle cell mitogenesis by ibuprofen

The aryl-propionic acid derivative, ketoprofen, has been shown to inhibit fibroblast growth by a cylooxygenase-dependent mechanism [Sánchez, T., Moreno, J.J., 1999. S(+) enantiomer inhibits prostaglandin production and cell growth in 3T6 fibroblast cultures. Eur. J. Pharmacol. 370, 63-67]. The present study demonstrates that ibuprofen, another aryl-propionic acid derivative, inhibited platelet-derived growth factor-BB (20 ng/ml)-induced mitogenesis of cultured bovine coronary artery smooth muscle cells in a stereo-independent manner. In addition, pretreatment of the cells with indomethacin (3 microM) did not affect the inhibitory effects of ibuprofen enantiomers on smooth muscle cell mitogenesis. Thus, aryl-propionic acid-type cyclooxygenase inhibitors can inhibit cell proliferation by both, cyclooxygenase-dependent and -independent ways.     

Modulation of H2O2-induced mitogen-activated protein kinases activation and cell death in SK-N-MC cells by EUK134, a salen derivative

Alzheimer's disease is a neurodegenerative disorder that is characterized by the accumulation of senile plaques containing amyloid β (Aβ) and neurofibrillary tangles composed of hyperphosphorylated tau protein in the brain. Oxidative stress has been proposed to mediate Aβ-induced neurotoxicity. In that regard, we evaluated the ability of EUK134, a superoxide dismutase and catalase mimics, to protect human neuroblastoma cell line SK-N-MC against H(2)O(2) -induced oxidative stress. Our data clearly indicated that cell death induced by H(2)O(2) was reversed by EUK134. Likewise, lipid peroxidation, caspase-3 activation and intracellular reactive oxygen species formation all returned to control levels following pre-treatments with EUK134. Elevated phosphorylation of mitogen-activated protein kinases (MAPK) induced by H(2)O(2) in SK-N-MC cells was lowered by EUK134 in a dose-dependent manner. In addition, EUK134 decreased expression of pro-apoptotic genes p53 and Bax and enhanced expression of anti-apoptotic Bcl-2 gene. Taken together, these results suggest that EUK134 protects neuronal cells against H(2)O(2) toxicity by attenuating oxidative stress through inhibition of MAPK phosphorylation cascade.     

莫诺苷抑制过氧化氢诱导的神经细胞损伤作用

目的研究从中药山茱萸提取的有效成分莫诺苷抑制过氧化氢(H2O2)诱导的神经细胞氧化损伤作用。方法培养的人神经母细胞瘤细胞系SH-SY5Y细胞加入莫诺苷1、10、100μmol/L预孵育24h,加入H2O2300μmol/L作用18h诱导产生氧化损伤,测定细胞内细胞色素C及脑源性神经生长因子(BDNF)的含量。结果莫诺苷1、10、100μmol/L使细胞色素C的释放显著降低18%(P<0.05)、28%(P<0.05)、35%(P<0.01);BDNF(10、100mol/L)的释放增加(P<0.01)。结论莫诺苷的神经保护作用是通过抑制细胞色素C的释放,抑制神经细胞凋亡,并能促进神经细胞增加神经营养因子的释放,进而促进神经细胞的再生,抑制神经细胞氧化损伤。     

Mechanism underlying H2O2-induced inhibition of acetylcholine-induced contraction in rabbit tracheal smooth muscle

The mechanism underlying the inhibition by H2O2 of acetylcholine-induced contraction was investigated in epithelium-denuded strips of rabbit trachea. Acetylcholine (10 microM) generated a phasic, followed by a tonic increase in both the intracellular Ca2+ concentration ([Ca2+]i) and force. Although the acetylcholine-induced tonic contraction was around 9 times the high K+ (80 mM)-induced one, the two stimulants induced similar [Ca2+]i increases (around 0.2 microM), indicating that acetylcholine generates tonic contraction via increases in both [Ca2+]i and myofilament Ca2+-sensitivity. H2O2 (30 microM) (a) enhanced the acetylcholine-induced tonic (not phasic) increase in [Ca2+]i but attenuated both phases of the acetylcholine-induced contraction and (b) enhanced the high K+-induced increase in [Ca2+]i but did not modify the high K+-induced contraction. In beta-escin-skinned strips, application of acetylcholine in the presence of GTP enhanced the contraction induced by 0.3 microM Ca2+ so that its amplitude became similar to that induced by 1 microM Ca2+. H2O2 (30 microM) attenuated the contraction induced by 0.3 microM Ca2+ (alone or in the presence of acetylcholine) but not those induced by higher concentrations of Ca2+ alone (0.5 microM and 1 microM). These results indicate that H2O2 acts directly on contractile proteins in rabbit tracheal smooth muscle to inhibit the contraction induced by low concentrations of Ca2+ (<0.5 microM). An action of H2O2 that increases [Ca2+]i (and thereby masks this reactive-oxygen-induced inhibition of myofilament Ca2+-sensitivity) is apparent in the presence of high K+ but not of acetylcholine. Thus, in rabbit tracheal smooth muscle H2O2 downregulates myofilament Ca2+-sensitivity more potently during acetylcholine-induced contraction than during high-K+-induced contraction, leading to an effective inhibition of the former contraction.     

神经妥乐平对H2O2致PC12细胞损伤的保护作用

目的 探索神经妥乐平对H2O2诱导的PC12细胞氧化应激损伤的影响及其潜在机制.方法 用CCK-8法检测细胞存活率,以流式细胞术检测细胞氧化损伤的发生、细胞内活性氧的生成及线粒体膜电位的变化,荧光显微镜观察细胞内活性氧的产生,qRT-PCR测定Caspase-3、Bax和Bcl-2 mRNA的表达.结果 PC12细胞存活率随H2O2浓度的增加而逐渐下降.其中,450μM H2O2处理细胞24 h后细胞存活率、凋亡率、坏死率明显降低;细胞内活性氧水平表达明显升高;线粒体膜电位JC-1红/绿荧光比值下降;Bax和Caspase-3的mRNA表达升高,而Bcl-2的mRNA表达下降,以上指标与对照组相比,差异有统计学意义(P＜0.05).而预先给予0.01UN/ml的NTP处理细胞12h可明显提高细胞存活率,降低细胞凋亡率和坏死率,减少细胞内活性氧生成并提高线粒体膜电位,抑制Bax和Caspase-3的mRNA表达,促进Bcl-2 mRNA的表达,以上指标与H2O2组相比,差异有统计学意义(P＜0.05).结论 NTP能抑制H2O2诱导的PC12细胞损伤,其神经细胞保护作用可能与其降低细胞内活性氧水平、维持线粒体膜电位的高能状态和抑制促凋亡基因表达、促进抗凋亡基因表达有关.     

Antioxidant ameliorating effects against H2O2-induced cytotoxicity in primary endometrial cells

Oxidative stress and a disrupted antioxidant system are involved in a variety of pregnancy complications. In the present study, the role of vitamin E (Vit E) and folate as radical scavengers on the GSH homeostasis in stress oxidative induced in rat endometrial cells was investigated. Primary endometrial stromal cell cultures treated with 50 and 200?µM of H₂O₂ and evaluated the cytoprotective effects of Vit E (5?µM) and folate (0.01?µM) in H₂O₂-treated cells for 24?h. Following the exposure of endometrial cells to H₂O₂ alone and in the presence of Vit E and/or folate, cell survival, glutathione peroxidase (GPx) and glutathione reductase activities and the level of reduced glutathione (GSH) were measured. Cell adhesions comprise of cell attachment and spreading on collagen were determined. Flow cytometric analysis using annexin V was used to measure apoptosis. H₂O₂ treatment showed a marked decrease in cell viability, GPx and GR activities and the level of GSH. Although Vit E or folate had some protective effect, combination therapy with Vit E and folate attenuated all the changes due to H₂O₂ toxicity. An increasing number of alive cells was showed in the cells exposed to H₂O₂ (50?µM) accompanied by co-treatment with Vit E and folic acid. The present findings indicate that co-administration of Vit E and folate before and during pregnancy may maintain a viable pregnancy and contribute to its clinical efficacy for the treatment of some idiopathic infertility.     

高糖增强过氧化氢诱导牛主动脉内皮细胞凋亡(英文)

目的:研究高糖对过氧化氢(H_2O_2)诱导牛主动脉内皮细胞(BAEC)凋亡作用。方法:BAEC培养并传代于正常葡萄糖(5.5 mmol·L~(-1))和高糖(25mmol·L~(-1))中,经H_2O_2处理24 h后,Hoechst 33258染色,荧光显微镜观察形态学变化及凋亡细胞计数;琼脂糖凝胶电泳分析DNA降解,Western blot法检测磷酸化p38 CCDPK表达。结果:H_2O_2诱导BAEC产生典型的凋亡细胞形态学变化(核浓染,核碎裂)。在100-300 μmol·L~(-1)范围内,正常糖和高糖BAEC经H_2O_2处理后,浓度依赖性诱导细胞凋亡和磷酸化p38 CCDPK表达。高糖条件下诱导BAEC DNA降解浓度低于正常糖BAEC,细胞凋亡率和磷酸化p38 CCDPK表达均显著高于正常糖组(p<0.05)。结论:高糖促进H_2O_2诱导BAEC凋亡,可能与其增强磷酸化p38 CCDPK的表达相关。     

布南色林对H2O2引起PC12细胞损伤的神经保护作用研究

目的 探讨布南色林对H2O2引起的PC12细胞损伤的保护作用。方法 用H2O2损伤PC12细胞建立神经元损伤模型,实验分空白细胞对照组（C组）,H2O2处理组（H组）,布南色林-过氧化氢处理组（B组）,阳性对照组（维生素E-过氧化氢处理组,E组）。MTT法检测细胞存活率;Hoechst33258以及TUNEL检测其对细胞凋亡影响;生化法测定超氧化物歧化酶（SOD）活性以及丙二醛（MDA）的含量。结果 与C组比较,H组的细胞存活率明显下降（P＜0.05）,凋亡指数增加,细胞内的SOD活性减低,MDA水平增高（P＜0.05）;与H组比较,B组的细胞活性增强,凋亡指数下降,细胞内的SOD活性加强,MDA水平减低（P＜0.05）。结论 合适浓度的布南色林对H2O2引起的神经损伤有保护作用。     

姜黄素对H_2O_2损伤PC12细胞的保护作用

目的　探讨姜黄素 (curcumin ,Cur)对氧化应激损伤PC12细胞的保护作用。方法　以H2 O2 损伤PC12细胞为氧化应激损伤的模型 ,采用甲氮甲唑蓝 (3 [4 ,5 dimethylthia zol 2 yl] 2 ,5diphenyltetrazoliumbromide ,MTT)法检测细胞增殖状况 ,碘化丙啶 (Propidiumiodide,PI)染色流式细胞术(flowcytometry ,FCM )检测细胞凋亡 ,罗丹明 12 3(Rho damine12 3,Rh12 3)染色FCM检测细胞线粒体膜电位 (mito chondrialpotentialmembrane ,△Ψm) ,双氢罗丹明 12 3(Dihy drohodamine12 3,DHR)染色FCM检测细胞内活性氧 (reac tiveoxygenspecies,ROS)的含量。 结果　 2 0和 4 0 μmol·L-1Cur均可使 2 5～ 4 0 0 μmol·L-1H2 O2 作用 2 4h后对PC12细胞生长的抑制率下降 ,可明显抑制 10 0和 2 0 0 μmo·L-1H2 O2 作用 2 4h后对PC12细胞凋亡的诱导作用和对PC12细胞△Ψm的降低作用 ,可明显降低 10 0和 2 0 0 μmol·L-1H2 O2 作用 12h后细胞内ROS的含量。结论　Cur对氧化应激损伤PC12细胞具有保护作用 ,其机制可能与降低细胞内ROS的含量 ,进而抑制△Ψm的降低有关。     

去甲二氢愈创木酸类似物对过氧化氢诱导细胞损伤的保护作用

目的 探讨去甲二氢愈创木酸(NDGA)类似物3g对过氧化氢(H2O2)诱导细胞氧化应激损伤的作用.方法 人神经母细胞瘤细胞系SH-SY5Y分为DMSO组(A组)、NDGA类似物3g 5μmol/L组(B组)、NDGA 5μmol/L组(C组)、H2 O2组(D组)、NDGA类似物3g 5μmol/L+H2 O2组(E组).采用MTT法检测细胞生存率,4',6-二脒基-2-苯基吲哚(DAPI)染色检测细胞凋亡情况,流式细胞术检测活性氧(ROS)水平,试剂盒检测丙二醛(MDA)水平,免疫荧光观察核因子E2相关因子2(Nrf2)入核情况,Western blot法检测Bax、Bcl-2、血红素氧化酶1(HO-1)和谷氨酸半胱氨酸连接酶催化亚基(GCLC)的蛋白表达.结果 B组和C组细胞生存率较A组增加(P<0.05).与A组相比,D组细胞发生凋亡现象,细胞生存率降低,MDA和ROS水平升高(P<0.05);而E组加入NDGA类似物3g后能逆转上述变化过程(P<0.05).与A组相比,D组和E组Bax蛋白表达增加,Bcl-2蛋白表达减少(P<0.05),D组变化更加明显(P<0.05).B组经NDGA类似物3g处理后能够诱导Nrf2进入细胞核.B组HO-1和GCLC蛋白表达较A组增加(P<0.05).结论 NDGA类似物3g通过降低ROS和MDA水平及细胞凋亡,并激活Nrf2通路,从而起到细胞保护作用.     

Activation of ERK1/2, JNK and PKB by hydrogen peroxide in human SH-SY5Y neuroblastoma cells: role of ERK1/2 in H2O2-induced cell death

Reactive oxygen species including H(2)O(2) activate an array of intracellular signalling cascades that are closely associated with cell death and cell survival pathways. The human neuroblastoma SH-SY5Y cell line is widely used as model cell system for studying neuronal cell death induced by oxidative stress. However, at present very little is known about the signalling pathways activated by H(2)O(2) in SH-SY5Y cells. Therefore, in this study we have investigated the effect of H(2)O(2) on extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase B (PKB) activation in undifferentiated and differentiated SH-SY5Y cells. H(2)O(2) stimulated time and concentration increases in ERK1/2, JNK and PKB phosphorylation in undifferentiated and differentiated SH-SY5Y cells. No increases in p38 MAPK phosphorylation were observed following H(2)O(2) treatment. The phosphatidylinositol 3-kinase (PI-3K) inhibitors wortmannin and LY 294002 ((2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one) inhibited H(2)O(2)-induced increases in ERK1/2 and PKB phosphorylation. Furthermore, H(2)O(2)-mediated increases in ERK1/2 activation were sensitive to the MAPK kinase 1 (MEK1) inhibitor PD 98059 (2'-amino-3'-methoxyflavone), whereas JNK responses were blocked by the JNK inhibitor SP 600125 (anthra[1-9-cd]pyrazol-6(2H)-one). Treatment of SH-SY5Y cells with H(2)O(2) (1 mM; 16 h) significantly increased the release of lactate dehydrogenase (LDH) into the culture medium indicative of a decrease in cell viability. Pre-treatment with wortmannin, SP 600125 or SB 203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; p38 MAPK inhibitor) had no effect on H(2)O(2)-induced LDH release from undifferentiated or differentiated SH-SY5Y cells. In contrast, PD 98059 and LY 294002 significantly decreased H(2)O(2)-induced cell death in both undifferentiated and differentiated SH-SY5Y cells. In conclusion, we have shown that H(2)O(2) stimulates robust increases in ERK1/2, JNK and PKB in undifferentiated and differentiated SH-SY5Y cells. Furthermore, the data presented clearly suggest that inhibition of the ERK1/2 pathway protects SH-SY5Y cells from H(2)O(2)-induced cell death.     

免疫球蛋白IgG对H_2O_2所致内皮细胞损伤的抑制作用及其机制

目的探讨免疫球蛋白IgG对H2O2诱导的内皮细胞的黏附分子和趋化因子的表达及作用机制。方法IgG和H2O2加入内皮细胞中孵育2 h,应用RT-PCR以及实时定量RT-PCR检测黏附因子(ICAM-1、VCAM-1、E-se-lectin)及趋化因子(MCP-1、CXCL-1、MIP-2)的mRNA及蛋白表达;进一步应用Western blot检测IgG对H2O2诱导的p38、ERK1/2和JNK1/2的磷酸化情况。结果 H2O2可显著诱导黏附分子(ICAM-1、VCAM-1和E-selectin)、趋化因子(MCP-1、CXCL-1、MIP-2)的表达,而IgG对H2O2诱导的这些因子的表达有抑制作用;且IgG可抑制H2O2诱导的p38、JNK1/2和ERK1/2的磷酸化。结论 IgG对H2O2诱导的内皮细胞黏附分子及趋化因子表达的抑制作用可能通过抑制p38、JNK1/2、ERK1/2的信号通路实现,这可能是IgG调节内皮细胞炎症的机制之一。     

K-RAS transformation in prostate epithelial cell overcomes H2O2-induced apoptosis via upregulation of gamma-glutamyltransferase-2

The anti-apoptotic oncogene K-RAS is hypothesized to increase the antioxidant status of cells, thereby protecting them from generation of reactive oxygen species (ROS). Therefore, we examined whether K-RAS overcomes hydrogen peroxide (H₂O₂)-mediated apoptosis in the human fetal prostate epithelial cell 267B1. In this study, we found that treatment of 267B1 cells with H₂O₂ resulted in significant reduction of cell growth, which was associated with cytochrome-c release and caspase-3 activation. However, mutated K-RAS transformation (268B1/K-RAS) rendered 267B1 cells reduction of the resistance to H₂O₂-induced apoptosis through suppression of ROS generation. In addition, we analyzed profiling of gene expression in K-RAS transformation and found that gamma-glutamyltransferase 2 (GGT2) most highly expressed. Transient knockdown of K-RAS resulted in a significant downregulation of GGT gene expression. We also revealed that expression of GGT2 gene is closely regulated by the ERK signal pathway in 267B1/K-RAS cells. In addition, the anti-apoptotic effect of mutated K-RAS was attenuated by treatment with GGT2 RNA interference through inhibition of ROS generation, suggesting that mutated K-RAS mediates resistance to H₂O₂-induced apoptosis through GGT2 activation. These results importantly provide mechanistic insights on the anti-apoptotic activity of mutated K-RAS.     

Evidence against inhibition of sarcoplasmic reticulum Ca2+-pump as mechanism of H2O2-induced contraction of rat aorta.

AIM: To test whether inhibition of sarcoplasmic reticulum (SR) Ca2+-pump is involved in H2O2-induced contraction of endothelium-denuded rat aorta. METHODS: Isometric tension recording of H2O2 and cyclopiazonic acid (CPA)-induced contractions of rat aortic rings were compared in the absence or presence of various pharmacological tools to discriminate their signaling pathways involved. RESULTS: Both H2O2 and CPA contracted rat aortic rings, but with different contractile patterns. H2O2 triggered a fast and phasic contraction, whereas CPA elicited a slow and sustained contraction. In Ca2+-free medium, pretreatment of aortic rings with CPA 30 micromol/L but not with H2O2 30 micromol/L nearly abolished phenylephrine (10 micromol/L)-induced contraction. In addition, upon the maximal contraction induced by thapsigargin 30 micromol/L, H2O2 but not CPA further contracted aortic rings. On the other hand, H2O2 (30 micromol/L)- but not CPA (10 micromol/L)-induced contraction could be inhibited by suramin and RB-2 (each 100 micromol/L), two P2-purinoceptor antagonists. Furthermore, although pretreatment with 2-APB, a membrane permeable IP3 receptor blocker, inhibited both H2O2- and CPA-induced contractions, only H2O2 (30 micromol/L)-induced contraction could be depressed, to different degree, by various inhibitors of receptor-coupled or downstream signaling enzymes, including PLC, PKC, PLA2, COX, and protein tyrosine kinases. CONCLUSION: Inhibition of smooth muscle SR Ca2+-pump is unlikely the mechanism responsible for H2O2-induced contraction of endothelium-denuded rat aorta.     

氯苄四氢小檗碱对抗H2O2引起无血清培养的血管内皮细胞凋亡及坏死

目的：研究氯苄四氢小檗碱对过氧化氢（H2O2）引起无血清培养的小牛主动脉血管内皮细胞的凋亡、增殖、坏死的影响。方法：通过体外细胞培养，以噻唑兰（MTT）法测定细胞存活率；用流式细胞术检测细胞DNA含量及凋亡细胞百分率、增殖率；DNA琼脂糖凝胶电泳法观察细胞凋亡过程中DNA断裂程度。结果：H2O2诱导无血清培养的内皮细胞凋亡，氯苄四氢小檗碱可显降低内皮肌细胞中凋亡细胞百分率，并抑制其增殖，也减少凋亡细胞DNA断裂，同时也减少其引起的平滑肌细胞坏死。结论：氯苄四氢小檗碱可对抗H2O2引起的无血清培养的血管平滑肌细胞凋亡、增殖及坏死。