YC-1对人低氧HepG-2细胞系内HIF-1稳定性及其促靶基因转录活性抑制效应的观察

目的:观察3-(5'-羟甲基-2'-呋喃)-1-苄基吲唑(YC-1)对低氧肝癌HepG-2细胞系缺氧诱导因子-1(HIF-1)稳定性和其促靶基因转录活性的调节作用,以及对细胞增殖活性的影响,探讨将HIF-1作为肿瘤治疗新靶点的可能性.方法:低氧条件下培养肝癌HepG-2细胞,应用RT-PCR和蛋白质印迹法分别检测不同YC-1作用浓度下HIF-1α及其靶基因mRNA和蛋白产物的表达.MTT检测YC-1时低氧HepG-2细胞恶性增殖力的影响.结果:低氧引起HIF-1α、VEGF和GPI mRNA表达显著增加,与常氧组比较差异有统计学意义,P<0.05.低氧条件下,YC-1以剂量依赖性方式抑制VEGF、GPI mRNA与蛋白表达,与对照组比较差异有统计学意义,P<0.05.低氧条件下,YC-1浓度升高不影响HIF-1α mRNA表达量,却以剂量依赖性方式抑制HIF-1α蛋白表达.低氧条件下,YC-1显著抑制HepG-2细胞生长,且呈现剂量依赖效应.结论:低氧状态下,Yc-1抑制人肝癌HepG-2细胞系内HIF-1稳定性和转录活性,且呈剂量依赖性.YC-1抑制HepG-2细胞生长,且呈现剂量依赖效应.     

乏氧条件下雷帕霉素对乳腺癌细胞增殖的抑制作用

目的 探讨乏氧条件下雷帕霉素(RPM)对乳腺癌细胞的影响及其机制。方法 MTT法检测乏氧条件下RPM对乳腺癌细胞株MCF-7细胞增殖的抑制作用,采用定量RT-PCR和Western blot检测缺氧诱导因子(HIF-1α)、VEGF基因mRNA和蛋白表达。结果 缺氧条件下,RPM对MCF-7细胞生长有抑制作用;HIF-1α蛋白水平随着RPM浓度提高而降低(P＜0.01),而HIF-1α mRNA表达水平无明显变化;VEGF的转录和蛋白表达均随着RPM浓度升高抑制率增加(P＜0.01),呈剂量依赖性。结论 RPM能抑制乳腺癌的肿瘤缺氧反应,从而抑制肿瘤的生长和血管的生成。     

缺氧对骨肉瘤SaOS-2细胞系HIF-1α和VEGF表达的影响

目的：观察缺氧条件下骨肉瘤SaOS-2细胞系缺氧诱导因子HIF-1α和血管生长因子VEGF表达的变化。方法：建立骨肉瘤细胞体外缺氧培养模型，观察缺氧培养不同时相(8、16、24h)HIF-1α和VEGF的表达。半定量RT—PCR方法检测HIF-1α和VEGF mRNA的转录水平，免疫组化(SP法)和免疫印迹(Western blot)检测HIF-1α蛋白表达情况，免疫组化和ELISA法检测细胞和培养上清液中VEGF蛋白表达。结果：缺氧处理后，HIF-1α mRNA转录水平没有明显改变，蛋白表达随缺氧时间延长而升高。VEGF mRNA以及蛋白的表达在缺氧条件下均显著增强。结论：骨肉瘤细胞系SaOS-2在缺氧条件下．缺氧诱导因子HIF-1α和血管牛长因子VEGF蛋白表达上调。     

HIF-1α基因干扰对大鼠CBRH-7919肝癌细胞HIF-1α与VEGF表达影响的研究

目的:探讨沉默缺氧诱导因子-1α(HIF-1α)对肝癌细胞在缺氧状态下表达HIF-1α及血管内皮生长因子(VEGF)的影响.方法:选用大鼠CBRH-7919肝癌细胞株作为研究对象,利用氯化钴(CoCl2)模拟缺氧状态,构建3组特异性较强的HIF-1α siRNA表达载体,采用小分子RNA干扰技术沉默细胞HIF-1α的基因表达,分别利用real time RT-PCR和蛋白质印迹法检测肝癌细胞HIF-1α和VEGF在mRNA及蛋白水平的表达变化.结果:在不同浓度CoCl2模拟缺氧条件下,随着CoCl2浓度的增高及时间的推移,肝癌细胞HIF-1α和VEGF的表达(mRNA及蛋白水平)较常氧对照组(0 μmol/L CoCl2)显著增多,差异均有统计学意义,P＜0.05.应用3组不同HIF-1α和siRNA表达载体转染缺氧条件下的肝癌细胞后,细胞的HIF-1α和VEGF的基因(mRNA)表达量与未转染HIF-1α siRNA表达载体对照组相比较明显减少,同步检测两者的蛋白表达亦明显减少,与对照组差异均有统计学意义,P＜0.05.结论:缺氧可以诱导肝癌细胞HIF-1α和VEGF的表达,siRNA沉默HIF-1α能显著抑制缺氧状态下诱导的VEGF表达.     

YC-1对人肝细胞癌裸鼠移植瘤的影响及其机制

目的探讨缺氧诱导因子抑制剂（YC-1）对人肝癌细胞裸鼠皮下移植瘤的影响及其相关机制。方法用人肝癌细胞株SMMC-7721建立人肝癌裸鼠皮下移植瘤模型,待肿瘤生长至约（100~150）mm3时,将荷瘤裸鼠随机分为两组：实验组和对照组,分别给予YC-1和二甲基亚砜,观察两组裸鼠肿瘤生长情况;应用RT-PCR、Western blot及免疫组织化学方法检测移植瘤组织HIF-1α和VEGF表达。结果YC-1治疗组各时点肿瘤体积显著低于对照组(P<0. 05 );与对照组比较,实验组移植瘤组织HIF-1α mRNA表达差异无统计学意义(P>0.05),而HIF-1α蛋白的表达显著降低 (P<0. 05 );移植瘤组织VEGFmRNA及蛋白表达均显著低于对照组 (P<0. 05 )。结论YC-1可能通过下调HIF-1α和VEGF的表达来抑制肝癌的生长。     

HIF-1α抑制剂YC-1对人骨肉瘤细胞Saos2和U2-OS增殖和凋亡的影响

目的:应用缺氧诱导因子-1α（hypoxia inducible factor-1α,HIF-1α）抑制剂YC-1处理人骨肉瘤细胞Saos2和U2-OS，观察不同药物浓度对人骨肉瘤细胞系Saos2和U2-OS细胞增殖、细胞周期以及凋亡的影响及其机制。方法:人骨肉瘤细胞系Saos2和U2-OS分对照组和实验组。对照组细胞1%氧气浓度低氧培养，实验组细胞施加HIF-1α抑制剂YC-1干预，设浓度梯度。CCK-8法检测不同药物浓度对Saos2和U2-OS细胞活力及增殖的影响；流式细胞术检测YC-1对Saos2和U2-OS细胞周期和凋亡的影响；Western blot对FXR1、G3BP1、APAF1、Cleaved Caspase-3蛋白的表达进行相对定量分析。结果:CCK-8检测结果显示，YC-1对人骨肉瘤Saos2和U2-OS细胞有显著的增殖抑制作用，且呈明显的剂量依赖效应。不同浓度的YC-1处理细胞后，均可使各处理组G1期细胞增多，S期细胞减少，且呈剂量依赖效应(P＜0.05)。不同浓度的YC-1处理细胞后，与对照组相比，各实验组FXR1、G3BP1、APAF1蛋白表达显著下降(P＜0.05)，而Cleaved Caspase-3蛋白表达显著增高(P＜0.05)。结论:YC-1可以将人骨肉瘤细胞株Saos2和U2-OS细胞阻滞于G1期，影响细胞周期进程，抑制细胞增殖，促进细胞凋亡。HIF-1α对人骨肉瘤细胞增殖与凋亡的影响可能是通过上调FXR1、G3BP1、APAF1的表达而实现，而YC-1抑制了HIF-1α的表达从而使Cleaved Caspase-3的表达增高诱导细胞凋亡。HIF-1α及FXR1、G3BP1、APAF1、Cleaved Caspase-3有望成为骨肉瘤治疗的新靶标。     

羟基喜树碱对缺氧诱导的SiHa细胞HIF-1α及VEGF基因表达的影响

目的:研究羟基喜树碱(hydroxycamptothecin,HCPT)对缺氧诱导的宫颈癌SiHa细胞HIF-1α和VEGF基因表达的影响。方法:在缺氧条件下(37℃,5%CO2,1%O2饱和度)体外培养宫颈癌SiHa细胞株,经不同浓度HCPT处理24 h后,用半定量RT-PCR法和Western印迹法分别检测细胞HIF-1α和VEGF mRNA及蛋白表达变化,并设立药物处理常氧组和缺氧对照组进行比较。结果:HCPT对常氧组与缺氧组细胞的细胞毒性作用无明显差异。在常氧条件下,SiHa细胞内无HIF-1α蛋白表达,VEGF有低水平表达,HCPT处理对SiHa细胞HIF-1α和VEGF基因表达无影响;但缺氧可诱导细胞HIF-1α和VEGF基因表达明显上调;HCPT对缺氧细胞HIF-1α蛋白和VEGF mRNA及蛋白表达有明显抑制作用,其效应呈剂量依赖性,而对HIF-1αmRNA表达无明显抑制作用。结论:HCPT可抑制缺氧诱导的SiHa细胞内HIF-1α蛋白及其下游VEGF基因的高表达。     

水蛭抑制肿瘤血管生成的作用及其机制

目的 探讨水蛭能否通过改善肿瘤细胞缺氧微环境来抑制肿瘤血管生成及其相关机制.方法 以氯化钴模拟化学缺氧,采用MTT法观察水蛭含药血清对EA.hy926细胞的增殖抑制作用;采用RTPCR法检测缺氧诱导因子-1α(HIF-1α)mRNA、血管内皮生长因子(VEGF) mRNA的表达;Western blot法检测HIF-1α蛋白水平;Matrigel基质胶模拟体外小管形成实验检测小管生成情况.结果 在缺氧条件下,水蛭含药血清能抑制EA.hy926细胞的增殖,且呈时间和剂量依耐性.水蛭含药血清在低氧时可显著抑制HIF-1α mRNA、VEGF mRNA的表达和HIF-1α蛋白水平,与阴性对照组比较,差异有统计学意义(P＜0.05);水蛭高剂量组和阳性对照组HIF 1α mRNA表达及其蛋白表达水平相当(P＞0.05),而VEGF mRNA在高剂量水蛭作用后的表达更少(P＜0.05).小管形成实验中,水蛭含药血清作用后小管数目与阴性对照组相比明显减少,差异有统计学意义(P＜0.05),与阳性对照组相比,差异无统计学意义(P＞0.05).结论 水蛭能通过改善肿瘤缺氧微环境抑制肿瘤血管生成来发挥抗肿瘤作用,其机制可能是通过降低HIF-1α蛋白水平和mRNA的表达,以及降低由HIF-1α所介导的靶基因VEGF mRNA的表达来实现的.     

紫云英苷通过上调PHD2抑制缺氧诱导的卵巢癌细胞增殖和侵袭

目的 探索紫云英苷(ATG)抑制卵巢癌细胞HIF-1α表达及细胞增殖和侵袭的作用及机制。方法 分别给予缺氧条件培养的OVCAR-8和SK-OV-3细胞ATG(ATG组)或ATG联合PHD2抑制剂IOX2(ATG+IOX2组)处理24h,并以仅缺氧培养24h的细胞为空白对照。采用Western blot和实时荧光定量PCR检测各组细胞HIF-1α、PHD2、PCNA、MMP-2和MMP-9蛋白和mRNA表达变化;以正常条件培养的细胞为阴性对照,采用缺氧试剂盒检测ATG处理后细胞缺氧状态变化;采用Transwell实验检测各组细胞侵袭能力;采用CCK-8试剂盒检测各组细胞增殖活力。分别以梯度浓度的ATG联合梯度浓度的卡铂或顺铂处理OVCAR-8和SK-OV-3细胞72h后采用CCK-8试剂盒检测细胞增殖活力,并进行联合效应分析。结果 缺氧培养条件下,与空白对照组相比,ATG组OVCAR-8和SK-OV-3细胞PHD2蛋白及mRNA表达均升高,细胞增殖和侵袭能力均降低,HIF-1α蛋白表达均减少,PCNA、MMP-2和MMP-9蛋白及mRNA表达均降低,但HIF-1α的mRNA水平以及细胞缺氧状态无明显变化;而与ATG组相比,ATG+IOX2组OVCAR-8和SK-OV-3细胞增殖和侵袭能力均增加,PCNA、MMP-2、MMP-9蛋白和mRNA表达及HIF-1α蛋白表达均升高,但HIF-1α的mRNA水平无明显变化。此外,ATG可明显增强OVCAR-8和SK-OV-3细胞对顺铂和卡铂的敏感性,具有较好的联合效应。结论 ATG可通过上调PHD2表达,促进缺氧诱导的HIF-1α降解,进而抑制卵巢癌细胞增殖和侵袭。     

缺氧条件下缺氧诱导因子-1α抑制剂YC-1对人卵巢癌Skov3干细胞耐药的逆转作用

目的:探讨缺氧诱导因子-1α抑制剂YC-1在缺氧条件下逆转人卵巢癌干细胞Skov3耐药的机制。方法:选用人卵巢癌Skov3细胞通过无血清悬浮培养法富集肿瘤干细胞。分别于常氧及缺氧条件下检测不同浓度顺铂干预Skov3贴壁细胞及干细胞后测定顺铂对于两种细胞的抑制作用,及缺氧后干性指标、耐药指标ABCG2及HIF-1α的表达。当给予HIF-1α抑制剂YC-1后,测定顺铂对Skov3干细胞的抑制作用。并且检测干细胞干性指标、ABCG2及HIF-1α的mRNA表达。结果:悬浮培养的Skov3干细胞的干性指标CD44、NANOG、OCT-4及耐药指标ABCG2较贴壁细胞升高,且缺氧培养后,随着HIF-1α表达的升高,CD44、NANOG、OCT-4及ABCG2的表达也明显升高,P<0.05。干细胞的耐药性高于贴壁细胞,且缺氧培养耐药性增加。当给予YC-1后,干细胞耐药性下调,HIF-1α出现抑制,同时其干性指标CD44、NANOG、OCT-4、耐药ABCG2明显下调,P<0.05。结论:YC-1在缺氧条件下通过抑制HIF-1α下调ABCG2的表达逆转Skov3干细胞耐药。     

YC-1 exerts inhibitory effects on MDA-MB-468 breast cancer cells by targeting EGFR in vitro and in vivo under normoxic condition

3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole(YC-1),the hypoxia-inducible factor-1 alpha(HIF-1α) inhibitor,suppresses tumor proliferation and metastasis by down-regulating HIF-1α expression under hypoxic conditions.Our previous studies demonstrated that YC-1 inhibited breast cancer cell proliferation under normoxic conditions.In the current study,we investigated the targets of YC-1 and mechanism of its action in MDA-MB-468 breast cancer cells.In the in vitro experiments,we found that YC-1 significantly inhibited MDA-MB-468 cell proliferation in normoxia and hypoxia.Under normoxic conditions,YC-1 induced apoptosis of MDA-MB-468 cells and blocked cell cycle in the G1 phase,and these effects were possibly related to caspase 8,p21,and p27 expression.RT-PCR and Western blotting results showed that YC-1 primarily inhibited HIF-1α at the mRNA and protein levels under hypoxic conditions,but suppressed the expression of epidermal growth factor receptor(EGFR) at the mRNA and protein levels under normoxic conditions.In vivo,YC-1 prolonged survival,increased survival rate,decreased tumor size and metastasis rate,and inhibited tissue EGFR and HIF-1α expression.However,YC-1 exerted no obvious effect on body weight.These results indicate that YC-1 inhibits the proliferation of MDA-MB-468 cells by acting on multiple targets with minimal side effects.Thus,YC-1 is a promising target drug for breast cancer.     

YC-1 induces S cell cycle arrest and apoptosis by activating checkpoint kinases

Hypoxia-inducible factor-1alpha (HIF-1alpha) seems central to tumor growth and progression because it up-regulates genes essential for angiogenesis and the hypoxic adaptation of cancer cells, which is why HIF-1alpha inhibition is viewed as a cancer therapy strategy. Paradoxically, HIF-1alpha also leads to cell cycle arrest or the apoptosis of cancer cells. Thus, the possibility cannot be ruled out that HIF-1alpha inhibitors unlock cell cycle arrest under hypoxic conditions and prevent cell death, which would limit the anticancer effect of HIF-1alpha inhibitors. Previously, we reported on the development of YC-1 as an anticancer agent that inhibits HIF-1alpha. In the present study, we evaluated the effects of YC-1 on hypoxia-induced cell cycle arrest and cell death. It was found that YC-1 does not reverse the antiproliferative effect of hypoxia, but rather that it induces S-phase arrest and apoptosis at therapeutic concentrations that inhibit HIF-1alpha and tumor growth; however, YC-1 did not stimulate cyclic guanosine 3',5'-monophosphate production in this concentration range. It was also found that YC-1 activates the checkpoint kinase-mediated intra-S-phase checkpoint, independently of ataxia-telangiectasia mutated kinase or ataxia-telangiectasia mutated and Rad3-related kinase. These results imply that YC-1 does not promote the regrowth of hypoxic tumors because of its cell cycle arrest effect. Furthermore, YC-1 may induce the combined anticancer effects of HIF-1alpha inhibition and cell growth inhibition.     

Ellagitannin-rich pomegranate extract inhibits angiogenesis in prostate cancer in vitro and in vivo

Angiogenesis is critical to tumor growth and is stimulated by tissue hypoxia due to poor oxygen delivery. In turn, cellular hypoxia leads to angiogenesis via the induction of hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) at a cellular level. Pomegranate juice and extracts, which are rich sources of ellagitannins, have been shown to have chemopreventive potential against prostate cancer, but there have been no studies on the effects of an ellagitannin-rich pomegranate extract on angiogenesis. Human prostate cancer cells (LNCaP) and human umbilical vein endothelial cells (HUVEC) were incubated with a pomegranate extract standardized to ellagitannin content (POMx), under normoxic and hypoxic conditions in vitro. Human prostate cancer cells (LAPC4) were injected subcutaneously into severe combined immunodeficient (SCID) mice and the effects of oral administration of POMx on tumor growth, microvessel density, and HIF-1alpha and VEGF expression were determined after 4 weeks of treatment. POMx inhibited the proliferation of LNCaP and HUVEC cells significantly under both normoxic and hypoxic conditions. HIF-1alpha and VEGF protein levels were also reduced by POMx under hypoxic conditions. POMx decreased prostate cancer xenograft size, tumor vessel density, VEGF peptide levels and HIF-1alpha expression after 4 weeks of treatment in SCID mice. These results demonstrate that an ellagitannin-rich pomegranate extract can inhibit tumor-associated angiogenesis as one of several potential mechanisms for slowing the growth of prostate cancer in chemopreventive applications. Further studies in humans are needed to confirm that angiogenesis can be inhibited by an ellagitannin-rich pomegranate extract administered orally as a dietary supplement.     

Resistance to caspase-dependent, hypoxia-induced apoptosis is not hypoxia-inducible factor-1 alpha mediated in prostate carcinoma cells

BACKGROUND: Hypoxia occurs in association with cancer development, the result being a more aggressive and metastatic cancer phenotype. Hypoxia, which activates hypoxia-inducible factor-1 alpha (HIF-1alpha), is associated with a number of cellular changes including increased apoptotic resistance. The authors hypothesized that HIF-1alpha is central to the cell's ability to resist apoptosis induced during the hypoxia selection process. METHODS: PWR-1E, LNCaP, LNCaP-HOF, PC-3, and DU-145 cells were cultured in normoxic and hypoxic conditions. Apoptosis was assessed by propidium iodide DNA staining. Cleavage of specific substrates was used to assess caspase activity and Western blotting was used to assess mitochondrial release of cytochrome c and second mitochondria-derived activator caspase (SMAC)/Diablo. A dominant negative HIF-1alpha construct was transfected into the PC-3 and LNCaP cells to block HIF-1alpha activity. RESULTS: PC-3 and DU-145 were resistant to apoptosis induced by exposure to hypoxia, but the PWR-1E and LNCaP cells were susceptible. This induction of apoptosis in the LNCaP cells was caspase dependent but independent of cytochrome c release. Blocking the activity of HIF-1alpha had no effect on increased apoptotic susceptibility in the PC-3 cells. LNCaP-HOF cells, which were resistant to hypoxia-induced apoptosis, showed no increase in HIF-1alpha expression or activity. CONCLUSIONS: Apoptotic resistance is already established in cells that survive a hypoxic insult and whereas increased HIF-1alpha activity may be essential for the development of a more aggressive cancer phenotype, it may not be responsible for the initial selection of an apoptotic resistance phenotype.