Stable disease for four years in metastatic malignant melanoma treated with the heat shock protein inhibitor 17-AAG

Heat shock proteins, including HSP90, contribute to the stabilization of a number of key molecules implicated in proliferative pathways in cancer. Geldanamycin and related compounds are competitive inhibitors of HSP90 at the N-terminal ATP binding site. The geldanamycin derivative 17-allylamino, 17-demethoxygeldanamycin (17-AAG) was the first HSP90 inhibitor to enter clinical development. Here we describe a patient with metastatic malignant melanoma treated with 17-AAG. She enjoyed a period of stable disease for a period of 49 months on treatment. Prolonged disease stabilization may prove to be a clinically meaningful outcome for many molecularly targeted agents and the design of phase II studies of these novel therapies needs to consider the use of progression-free survival as a valid endpoint.     

Efficacy of the HSP90 inhibitor 17-AAG in human glioma cell lines and tumorigenic glioma stem cells

Glioblastoma multiforme (GBM) arises from genetic and signaling abnormalities in components of signal transduction pathways involved in proliferation, survival, and the cell cycle axis. Studies to date with single-agent targeted molecular therapy have revealed only modest effects in attenuating the growth of these tumors, suggesting that targeting multiple aberrant pathways may be more beneficial. Heat-shock protein 90 (HSP90) is a molecular chaperone that is involved in the conformational maturation of a defined group of client proteins, many of which are deregulated in GBM. 17-allylamino-17-demethoxygeldanamycin (17-AAG) is a well-characterized HSP90 inhibitor that should be able to target many of the aberrant signal transduction pathways in GBM. We assessed the ability of 17-AAG to inhibit the growth of glioma cell lines and glioma stem cells both in vitro and in vivo and assessed its ability to synergize with radiation and/or temozolomide, the standard therapies for GBM. Our results reveal that 17-AAG is able to inhibit the growth of both human glioma cell lines and glioma stem cells in vitro and is able to target the appropriate proteins within these cells. In addition, 17-AAG can inhibit the growth of intracranial tumors and can synergize with radiation both in tissue culture and in intracranial tumors. This compound was not found to synergize with temozolomide in any of our models of gliomas. Our results suggest that HSP90 inhibitors like 17-AAG may have therapeutic potential in GBM, either as a single agent or in combination with radiation.     

Synergistic interaction between 17-AAG and phosphatidylinositol 3-kinase inhibition in human malignant glioma cells

The phosphatidylinositol 3'-kinase (PI3K)/Akt pathway is often constitutively activated in malignant glioma cells, in many cases as a result of mutation of phosphatase and tensin homologue deleted on chromosome ten (PTEN), an endogenous inhibitor of Akt, which renders tumor cells resistant to cytotoxic insults, including those related to anticancer drugs. Pharmacological inhibition of this pathway may potentially restore or augment the effectiveness of conventional chemotherapy or other signaling-targeted agents. Because the heat shock protein (HSP) is involved in the conformational maturation of a number of signaling proteins critical to the proliferation of malignant glioma cells, we hypothesized that the combination of the PI3K inhibitor LY294002 and the HSP90 inhibitor 17-allyl-aminogeldanamycin (17-AAG) would promote glioma cytotoxicity by decreasing both the activation status and levels of Akt, as well as downregulating the levels of other relevant signaling effectors. We, therefore, examined the effects of LY294002 and 17-AAG, alone and in combination, on signal transduction and apoptosis in a series of malignant glioma cell lines. Simultaneous exposure to these inhibitors significantly induced cell death, and irreversibly inhibited proliferative activity and colony forming ability of the glioma cell lines. Quantitative analysis revealed that enhancement by LY294002 of 17-AAG-induced cytotoxicity was synergistic, leading to a pronounced increase in active caspase-3 and poly (adenosine diphosphate-ribose) polymerase (PARP) cleavage together with the release of cytochrome c and apoptosis inducing factor (AIF). No significant growth inhibition or caspase activation was seen in control cells. The enhanced cytotoxicity of this combination was associated with diminished Akt activation and a significant downregulation of epidermal growth factor receptor (EGFR), Raf-1, and mitogen activated protein kinase. Combination of 17-AAG and LY294002 did not modify phospho-JNK/SPK and phospho-p38. Cells exposed to 17-AAG and LY294002 displayed a significant reduction in cell-cycle regulatory proteins, such as retinoblastoma (Rb), cyclin dependent kinase (CDK)4, CDK6, cyclin D1, and cyclin D3. Taken together, these findings suggest that the PI3K/Akt pathway plays a critical role in regulating the apoptotic response to 17-AAG and that targeting this pathway could provide a potent strategy to treat patients with malignant gliomas.     

Melatonin sensitizes human malignant glioma cells against TRAIL-induced cell death

Despite the common expression of death receptors, many types of cancer including gliomas are resistant to the death receptor ligand (TRAIL). Melatonin antitumoral actions have been extensively described, including oncostatic properties on several tumor types and improvement of chemotherapeutic regimens. Here, we found that melatonin effectively increase cell sensitivity to TRAIL-induced cell apoptosis in A172 and U87 human glioma cells. The effect seems to be related to a modulation of PKC activity which in turns decreases Akt activation leading to an increase in death receptor 5 (DR5) levels and a decrease in the antiapoptotic proteins survivin and bcl-2 levels.     

Targeting the 90 kDa heat shock protein improves photodynamic therapy

The geldanamycin derivative, 17-allylamino-17-demethoxygeldanamycin (17-AAG), binds to the amino-terminal ATP binding pocket of the 90 kDa heat shock protein (Hsp-90) and inhibits this chaperone from stabilizing client proteins involved with the malignant phenotype. We examined the effects of a combined modality protocol involving photodynamic therapy (PDT) and 17-AAG in mouse mammary carcinoma cells and tumors. PDT increased the expression of the anti-apoptotic and pro-angiogenic proteins survivin, Akt, HIF-1α, MMP-2 and VEGF in tumor tissue and this expression decreased significantly when 17-AAG was included in the treatment regimen. Tumor bearing mice treated with PDT and 17-AAG had improved long-term tumoricidal responses when compared with individual treatment protocols. We conclude that Hsp-90 plays an active role in modulating tumor responsiveness following PDT and targeting Hsp-90 with 17-AAG enhances the therapeutic effectiveness of PDT.     

Mode of cell death induced by the HSP90 inhibitor 17-AAG (tanespimycin) is dependent on the expression of pro-apoptotic BAX

Inhibitors of the molecular chaperone heat shock protein 90 (HSP90) are of considerable current interest as targeted cancer therapeutic agents because of the ability to destabilize multiple oncogenic client proteins. Despite their resulting pleiotropic effects on multiple oncogenic pathways and hallmark traits of cancer, resistance to HSP90 inhibitors is possible and their ability to induce apoptosis is less than might be expected. Using an isogenic model for BAX knockout in HCT116 human colon carcinoma cells, we demonstrate the induction of BAX-dependent apoptosis at pharmacologically relevant concentrations of the HSP90 inhibitor 17-AAG both in vitro and in tumor xenografts in vivo. Removal of BAX expression by homologous recombination reduces apoptosis in vitro and in vivo but allows a lower level of cell death via a predominantly necrotic mechanism. Despite reducing apoptosis, the loss of BAX does not alter the overall sensitivity to 17-AAG in vitro or in vivo. The results indicate that 17-AAG acts predominantly to cause a cytostatic antiproliferative effect rather than cell death and further suggest that BAX status may not alter the overall clinical response to HSP90 inhibitors. Other agents may be required in combination to enhance tumor-selective killing by these promising drugs. In addition, there are implications for the use of apoptotic endpoints in the assessment of the activity of molecularly targeted agents.     

An in vitro and in vivo study of the combination of the heat shock protein inhibitor 17-allylamino-17-demethoxygeldanamycin and carboplatin in human ovarian cancer models

PURPOSE: To study the interactions of the heat shock protein 90 (HSP90) inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) and carboplatin in vitro and in vivo. EXPERIMENTAL DESIGN: The combination of 17-AAG and carboplatin on the growth inhibition of A2780, SKOV-3, IGROV-1 and HX62 human ovarian cancer cells was studied in vitro by MTT assays. The effect of the sequence of administration of both drugs was further investigated in A2780 cells by sulforhodamine B assays. The ability of 17-AAG to deplete HSP90 client proteins either alone or in combination with carboplatin was evaluated by western blotting. Tumor concentrations of 17-AAG and carboplatin alone or in combination in vivo were determined by validated liquid chromatography with ultraviolet detection and atomic absorption spectroscopy methods. The growth inhibitory effects of 17-AAG, carboplatin and the combination were studied in the A2780 xenograft model. RESULTS: The combination index (CI) at fu(0.5) for 17-AAG plus carboplatin was 0.97 (+/-0.12 SD) when A2780 cells were exposed to carboplatin followed by 17-AAG indicating additivity. The addition of carboplatin did not alter the ability of 17-AAG to cause C-RAF, CDK4 and p-AKT depletion or HSP70 induction. Tumor 17-AAG and carboplatin concentrations were not significantly different in the single agent and combination arms. Tumor weights relative to controls on day 6 (T/C) were 67% for the carboplatin, 64% for the 17-AAG and 22% for the combination. CONCLUSION: In the specified sequences of drug exposure, 17-AAG and carboplatin have additive growth inhibitory effects in vitro and beneficial effects were seen with the combination in vivo. These findings form the basis for the possible evaluation of 17-AAG and carboplatin in a clinical trial.     

17-AAG通过抑制Erk信号通路增强奥沙利铂诱导结肠癌细胞凋亡

目的 研究17-AAG与奥沙利铂是否存在协同效应,并探讨PI3K/Akt、Erk信号通路在奥沙利铂联合17-AAG诱导人结肠癌细胞凋亡过程中的作用。方法 四甲基偶氮唑盐比色实验（MTT法）检测17-AAG、奥沙利铂对细胞增殖的抑制作用;流式细胞术分析细胞凋亡情况;Western blot法检测相关蛋白的表达水平。结果 17-AAG能抑制RKO细胞的增殖;17-AAG联合奥沙利铂作用于RKO细胞24 h后,G₂/M期细胞比例及凋亡率明显增加;奥沙利铂抑制p-Akt、p-Erk的活化,上调Bax,下调Bcl-2蛋白表达,活化裂解Caspase-3,联合使用17-AAG后可进一步增强上述作用,但对PI3K/Akt信号通路影响不大。结论 本实验表明17-AAG具有增强奥沙利铂诱导结肠癌RKO细胞凋亡的作用,同时也说明17-AAG与奥沙利铂存在协同效应;17-AAG上调Bax,下调Bcl-2蛋白表达及增强奥沙利铂对Erk信号通路的抑制作用可能是其促进凋亡的重要机制之一。     

Synergistic inhibition of the growth of MDA-MB-231 cells in triple-negative breast cancer by salinomycin combined with 17-AAG and its mechanism

Salinomycin (SAL), a typical ion carrier antibiotic, inhibits tumor growth and metastasis by inducing apoptosis or autophagy in cancer or cancer stem cells and thus overcomes drug resistance. 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein Hsp90 competitive inhibitor, also has a role in inhibiting tumor development. However, their combination on the growth of breast cancer cells and its specific mechanism remains to be elucidated. The present study tested the influence of SAL and 17-AAG on cell growth, apoptosis and autophagy by MTT assays, Annexin V-FITC and propidium iodide double staining assay and immunoelectron microscopy. The influence of SAL and 17-AAG on proteomics was investigated by isobaric tag for relative and absolute quantitation. It was found that SAL combined with 17-AAG synergistically inhibited the cell growth and induced the apoptosis in a concentration-dependent manner, with the expression of caspase 3 and Bcl-2 were decreased while the expression of Bax was increased. In addition, SAL combined with 17-AAG inhibited autophagy, with the expression of microtubule-associated protein 1 light chain 3, Beclin1, p62 being decreased. Mechanistically, SAL combined with 17-AAG synergistically inhibited the reactive oxygen species/JNK signaling pathway. In conclusion, SAL combined with 17-AAG had a synergistic inhibitory effect on cell growth of breast cancer via inducing apoptosis and inhibiting autophagy. The present study might provide a new strategy for potential clinical application of SAL as a new anti-tumor drug especially as a drug combination with other molecular targeting therapeutics.     

热休克蛋白90抑制剂对LoVo细胞生长及细胞周期的影响

背景与目的:热休克蛋白90(heat shock protein90,Hsp90)是体内重要的伴侣分子,体内许多重要的蛋白质是其底物蛋白质,但其本身不能降解底物蛋白,只能与底物相互作用,起到分子伴侣的作用.Hsp90抑制剂能抑制肿瘤细胞增殖,诱导肿瘤细胞凋亡,导致周期阻滞,破坏tfsp90与底物的结合及促进Hsp90底物蛋白质降解.为探讨Hsp90与生存素(Survivin)同时作为治疗靶点的效应及可能机制,本实验观察Hsp90抑制剂17-烯丙胺-17-脱甲氧格尔得霉素(17-AAG)对人结肠癌LoVo细胞增殖、细胞周期以及对周期相关蛋白Survivin水平的影响.方法:用四氮唑盐还原法(MTT法)检测17-AAG对LoVo细胞增殖影响;Propidium Iodide(PI)染色检测细胞周期变化;Western blot检测Hsp90底物蛋白Survivin的变化.结果:17-AAG呈时间-剂量-依赖性抑制LoVo细胞增殖.100、500、和800 ng/ml 17-AAG作用于LoVo细胞24 h后,细胞增殖抑制率分别为21.00%、40.81%、60.34%,作用48 h后,细胞增殖抑制率分别为27.29%、48.17%、80.97%,作用72 h,细胞增殖抑制率分别为34.45%、67.81%和88.42%.17-AAG导致LoVo细胞周期改变,100和500 ng/ml 17-AAG作用72 h,G0/G1期分别占(61±3)%及(74±3)%,LoVo细胞阻滞于G0/G1期,未加药处理的LoVo细胞G0/G1期比例仅为(48.2±0.8)%(P＜0.001).500 ng/ml 17-AAG作用于LoVo细胞72 h可部分清除Hsp90底物蛋白Survivin(P ＜0.001).结论:17-AAG呈时间-剂量依赖性抑制LoVo细胞增殖,阻滞LoVo细胞于G0/G1期,并能部分清除Survivin.     

p53上调凋亡调控因子增强胶质瘤干细胞对替莫唑胺化疗敏感性的研究

 目的　探讨不同CD133免疫原型的胶质瘤细胞对替莫唑胺（TMZ）耐药性的差异以及p53上调凋亡调控因子（PUMA）改变胶质瘤细胞对TMZ敏感性的影响。方法　利用免疫磁珠细胞分选法筛选出CD+133和CD-133的胶质瘤细胞U87MG,分别传代培养,转染Ad-PUMA,并用TMZ干预。四甲基偶氮唑蓝比色法（MTT法）检测细胞增殖情况及对TMZ的半数抑制浓度（IC50）,流式细胞术观察外源性PUMA、TMZ干预前后CD+133和CD-133细胞的凋亡情况。结果　CD+133免疫磁珠分选出胶质瘤干细胞,CD+133胶质瘤细胞IC50较CD-133胶质瘤细胞高[（200±10）μmol／L比（80±11）μmol／L],转染Ad-PUMA后,两组细胞IC50均降低[（100±8）μmol／L比 （20±7）μmol／L],两组转染前后IC50差异均有统计学意义（P < 0.05）。TMZ联合PUMA组CD+133细胞凋亡率为68.05 %,对照组、TMZ组及PUMA组分别为6.05 %、32.91 %和40.61 %,联合组与其他组比较差异均有统计学意义（均P＜0.05）。结论　PUMA联合TMZ可以促进耐药的胶质瘤干细胞凋亡,从而增强胶质瘤对化疗的敏感性。     

PTEN基因诱导人脑胶质瘤SHG-44细胞凋亡及bcl-2蛋白表达下调

目的　探讨PTEN基因对人脑胶质瘤SHG 44细胞凋亡及凋亡相关基因bcl 2表达的影响 ,阐明PTEN基因抑制肿瘤细胞增殖的机理。方法　PTEN基因体外转染SHG 44细胞 ,筛选阳性细胞克隆 ,以原位杂交、免疫组化方法检测PTEN基因的表达情况采用透射电镜、流式细胞仪和核DNA琼脂糖凝胶电泳检测细胞的凋亡情况以免疫荧光法检测bcl 2基因的表达。结果　PTEN基因转染的SHG 44细胞有PTEN基因和蛋白的表达。透射电镜下可见转染PTEN基因后细胞核染色质浓缩边集、胞浆浓缩、核碎裂及凋亡小体形成等典型的凋亡表现 ;流式细胞仪示细胞周期从G1 期到S期发生抑制 ,并且在G1 期峰前出现一明显的凋亡峰 (1 2 .9% ) ;细胞核DNA琼脂糖凝胶电泳呈现凋亡细胞特有的梯状条带 ;bcl 2的表达也显著下调。转染空载体和未转染的SHG 44细胞无明显的凋亡表现。结论　PTEN基因可诱导SHG 44细胞凋亡 ,并下调bcl 2蛋白的表达 ,这可能是PTEN基因抑制肿瘤细胞增殖的分子机制之一     

依托咪酯对神经胶质瘤细胞缝隙连接通讯的影响

背景与目的：细胞缝隙连接(gap junction,GJ)通讯能增强放疗或化疗药物对肿瘤细胞的细胞毒性作用。以往研究发现部分麻醉药物能够改变GJ功能从而影响肿瘤细胞对放疗的敏感性。该研究拟观察依托咪酯对神经胶质瘤细胞由缝隙连接蛋白Cx43组成的缝隙连接功能的影响,为麻醉药对化疗敏感性影响的机制研究提供线索。方法：采用磺酰罗丹明B法观察依托咪酯对神经胶质瘤细胞的抑制作用;细胞接种荧光法观察依托咪酯对神经胶质瘤细胞GJ功能的影响。结果：0.1、0.5、1和5μmol/L依托咪酯在作用4 h时间内均对细胞生长无抑制作用,将不影响细胞缝隙的数量;取药物浓度接近血药浓度的依托咪酯作用细胞4 h,与对照组相比,0.1μmol/L依托咪酯作用细胞4 h后,神经胶质瘤细胞GJ通讯的荧光传递功能无明显变化;而0.5和1μmol/L依托咪酯作用细胞4 h后,神经胶质瘤细胞的荧光传递功能明显减弱。结论：依托咪酯能抑制神经胶质瘤细胞Cx43组成的GJ功能。     

长链非编码RNA MEG3在人胶质瘤细胞中的表达及作用研究

目的 探究LncRNA MEG3对人胶质瘤细胞活力和凋亡的影响及其作用机制。方法 RT-qPCR检测人胶质瘤细胞系(U87)和正常星形胶质细胞系(NHAs)中MEG3、microRNA-21(miR-21)的表达;U87细胞单独转染MEG3质粒或同时转染MEG3质粒与miR-21 mimic后采用CCK-8检测细胞活力、TUNEL检测细胞凋亡、Western blot检测细胞内Bcl-2/Bax和Cleaved caspase-3表达。结果 与NHAs细胞相比,U87细胞中的MEG3表达明显下降,且miR-21表达明显上升。过表达MEG3明显降低U87的miR-21表达,抑制U87的活力,降低Bcl-2/Bax的水平,提高Cleaved caspase-3的含量,促进凋亡;共过表达MEG3和miR-21可明显增加U87的活力,提高Bcl-2/Bax的水平,降低Cleaved caspase-3的含量,抑制凋亡。结论 过表达MEG3通过抑制miR-21降低胶质瘤细胞的活力并促进其凋亡。     

敲低Yes相关蛋白表达对人脑胶质瘤细胞SNB19生长的抑制作用

目的：探究敲低Yes相关蛋白（YAP）对人脑胶质瘤细胞SNB19细胞生物学特征的影响。方法采用YAP干扰RNA（YAPsiRNA）敲低SNB19细胞中YAP的表达,Western blot法鉴定肿瘤细胞中YAP是否已被敲低;噻唑蓝（MTT）比色法测定YAP敲低后胶质瘤细胞的增殖能力;Transwell实验检测胶质瘤细胞侵袭能力的变化;流式细胞术和AnnexinⅤ标记法分别检测胶质瘤细胞周期及凋亡的变化。应用统计软件SPSS18．0进行统计学处理。结果 Western blot证实转染 YAPsiRNA 可有效敲低SNB19细胞中Yes相关蛋白的表达;敲低Yes相关蛋白的表达可以抑制胶质瘤细胞增殖活性,细胞存活率由（100．00±0．00）％下降为（52．32±3．10）％（F＝33．00,P＜0．01）,细胞周期阻滞于G0-G1期（F＝8．76,P＜0．01）,细胞侵袭能力明显受抑,穿膜细胞数由（163．20±10．10）个下降至（37．71±2．52）个（F＝282．05,P＜0．01）,凋亡增加,凋亡率由（3．56±0．35）％增加至（18．99±0．66）％（F＝931．99,P＜0．01）。结论敲低胶质瘤细胞SNB19中YAP表达可抑制肿瘤细胞增殖和侵袭,诱导细胞凋亡;YAP可成为人脑胶质瘤基因治疗的潜在靶点。     

过表达热休克蛋白22抑制造血系统恶性肿瘤细胞生长的研究

目的 探讨过表达热休克蛋白22（HSP22）对造血系统恶性肿瘤细胞生长和凋亡的影响.方法 构建含HSP22或空载体的慢病毒表达载体,感染K562和Namalwa细胞;荧光显微镜及流式细胞术观察感染效率;反转录-聚合酶链反应（RT-PCR）和Western blot鉴定HSP22表达.采用细胞计数法测定细胞增殖,流式细胞术检测细胞周期,甲基纤维素半固体集落形成实验测定集落数,Annexin VPE／7-AAD流式细胞术检测细胞凋亡.在裸鼠皮下注射K562和Namalwa细胞进行成瘤实验以观察成瘤体积.结果 与转导空载体的对照细胞相比,HSP22过表达能抑制Namalwa和K562细胞集落形成,每孔平均集落数转导pCDH1-MCS1-EF1-copGFP空载体的K562细胞为108,转导pCDH1-MCS1-EF1-copGFPHSP22的K562细胞为72,两者差异有统计学意义（P=0.000 16）;转导pCDH1-MCS1-EF1-copGFP空载体的Namalwa细胞为125,转导pCDH1-MCS1-EF1-copGFP-HSP22的Namalwa细胞为80,两者差异有统计学意义（P=0.000 37）.HSP22还能抑制Namalwa细胞体外增殖（第5天,P=0.015;第6天,P=0.042;第7天,P=0.048）,抑制K562细胞体内增殖（第21天,P=0.022）.K562、Namalwa细胞HSP22转导组与对照组间G0～G1期、G2～M期及S期细胞所占百分比差异均无统计学意义（均P＞ 0.05）.结论 过表达HSP22能够抑制造血系统恶性肿瘤K562和Namalwa细胞的生长.     

整合素αvβ3在脑胶质瘤的表达与肿瘤恶性程度的关系

 目的探讨整合素 αｖβ３与脑胶质瘤恶性程度之间的关系。方法应用免疫组化 ＳＡＢＣ法检测整合素 αｖβ３在 ４３例Ⅰ～Ⅳ级脑胶质瘤和 ＢＴ３２５人胶质瘤细胞系中的表达。结果Ⅲ～Ⅳ级脑胶质瘤阳性率及高表达率均明显高于 Ⅰ～Ⅱ级脑胶质瘤（Ｐ＜０．０５）。结论整合素 αｖβ３与脑胶质瘤恶性程度呈正相关，并可能对胶质瘤的侵袭性起正性调节作用     

Coadministration of the heat shock protein 90 antagonist 17-allylamino- 17-demethoxygeldanamycin with suberoylanilide hydroxamic acid or sodium butyrate synergistically induces apoptosis in human leukemia cells

Interactions between the histone deacetylase inhibitors (HDACIs) suberoylanilide hydroxamic acid (SAHA) and sodium butyrate (SB) and the heat shock protein (Hsp) 90 antagonist 17-allylamino-17-demethoxygeldanamycin (17-AAG) have been examined in human leukemia cells (U937). Coadministration of marginally toxic concentrations of 17-AAG with sublethal concentrations of SB or SAHA resulted in highly synergistic induction of mitochondrial damage (i.e., cytochrome c release), caspase-3 and -8 activation, and apoptosis. Similar interactions were noted in human promyelocytic (HL-60) and lymphoblastic (Jurkat) leukemia cells. These events were accompanied by multiple perturbations in signal transduction, cell cycle, and survival-related pathways, including early down-regulation of Raf-1, inactivation of extracellular signal-regulated kinase (ERK) 1/2 and mitogen-activated protein/ERK kinase (MEK) 1/2, diminished expression of phospho-Akt, and late activation of c-Jun-NH(2)-terminal kinase, but no changes in expression of phospho-p38 mitogen-activated protein kinase. Coadministration of 17-AAG blocked SAHA-mediated induction of the cyclin-dependent kinase inhibitor p21(CIP1) and resulted in reduced expression of p27(KIP1) and p34(cdc2). 17-AAG/SAHA-treated cells also displayed down-regulation of the antiapoptotic protein Mcl-1 and evidence of Bcl-2 cleavage. Enforced expression of doxycycline-inducible p21(CIP1) or constitutively active MEK1 significantly diminished 17-AAG/SAHA-mediated lethality, indicating that interference with ERK activation and p21(CIP1) induction play important functional roles in the lethal effects of this regimen. In contrast, enforced expression of constitutively active Akt failed to exert cytoprotective actions. Together, these findings indicate that coadministration of SAHA or SB with the Hsp90 antagonist 17-AAG in human leukemia cells leads to multiple perturbations in signaling, cell cycle, and survival pathways that culminate in mitochondrial injury and apoptosis. They also raise the possibility that combining such agents with Hsp90 antagonists may represent a novel antileukemic strategy.     

The effect of antisense epidermal growth factor receptor (EGFR) RNA on the proliferation of human glioma cells and induction of cell apoptosis

Malignantgliomaisoneofthemostdevastatingdiseases.Theprognosisofpatientshasnotbeenimprovedevenwhenthecurrentlyavailablec0mbinedtherapiesareused.Astheknowledge0ftumorbi0l0gyandmoleculargeneticshasgreatlyincreasedoverthepastdecades,ithasbeenshownthattumorigenesisbasicallyresultsfromtheactivation0fprotooncogenesandinactivati0n0ftumorsuppressorgenes.Sincegenesencodinggrowthfactorsandtheirreceptorsarecloselyrelatedtooncogenes,muchattentionhasbeenfocusedontheroleofgrowthfactorsandtheirreceptorsinthep…