Inhibition of Notch3 enhances sensitivity to gemcitabine in pancreatic cancer through an inactivation of PI3K/Akt-dependent pathway

Notch3 is one of the four Notch receptors identified in mammal, but its role in human pancreatic cancer remains poorly characterized. In this study, we sought to determine the effect of suppressing Notch3 expression on the chemosensitivity to gemcitabine in human pancreatic cancer cell lines BxPC-3 and PANC-1. RNA interference was used to suppress Notch3 expression. Gemcitabine-induced cytotoxicity was determined by MTT. Cell apoptosis was measured by flow cytometry. Caspase 3 activity was assayed using a Caspase Fluorescent Assay Kit. The effect of Notch3-specific siRNA on PI3K/Akt activity was also quantified. Notch3-specific siRNA suppressed Notch3 expression, and furthermore increased gemcitabine-induced, caspase-mediated apoptosis. The suppression of Notch3 expression decreased the average IC₅₀ in BxPC-3 and PANC-1 cells treated with gemcitabine. PI3K/Akt activity was decreased by the suppression of Notch3 expression. Taken together, these data demonstrated that Notch3 is a potential therapeutic target for pancreatic cancer, and PI3K/Akt is a key signaling component by which activation of the Notch3 signal transduction pathway protects pancreatic cancer cells from chemotherapy-induced cell death.     

Saposin C promotes survival and prevents apoptosis via PI3K/Akt-dependent pathway in prostate cancer cells

Background  

In addition to androgens, growth factors are also implicated in the development and neoplastic growth of the prostate gland. Prosaposin is a potent neurotrophic molecule. Homozygous inactivation of prosaposin in mice has led to the development of a number of abnormalities in the male reproductive system, including atrophy of the prostate gland and inactivation of mitogen-activated protein kinase (MAPK) and Akt in prostate epithelial cells.     

Knockdown of clusterin sensitizes pancreatic cancer cells to gemcitabine chemotherapy by ERK1/2 inactivation

ABSTRACT: ObjectivesTo study the hypothesis that gemcitabine treatment augments the chemoresistance to gemcitabine by clusterin(sCLU) upregulation. Clusterin inhibition could augment the chemosensitivity of human pancreatic cancer cells by inhibition of clusterin-dependent pERK1/2 activation. METHODS: Clusterin was silenced by serial concentration of OGX-011 transfection in pancreatic cancer MIAPaCa-2 and BxPC-3 cell lines, then treated with serial concentration of gemcitabine. After the cells were treated with OGX-011 for 8 h,the cells were then treated with 5 muM ERK inhibitor PD98059 for 18 h or transfected with a wt-pERK-expressing plasmid into these cells for 24 h, after which the cells were treated with 1.0 uM gemcitabine for 24--72 h. Cell proliferation was determined by MTT. Apoptosis was quantified by flow cytometry,.sCLU and pERK1/2 production was analyzed by western blot,and sCLU mRNA was analyzed by RT-PCR. Xenograft of established tumors was used to evaluate primary tumor growth and apoptosis after treatment with gemcitabine alone or in combination with OGX-011. Phosphorylated ERK1/2 and sCLU levels in tumor tissues were measured by TUNEL analysis. RESULTS: As detected by MTT and FACS assay, a combination of gemcitabine + OGX-011 reflected the chemotherapeutic sensitivity and increased the gemcitabine -induced apoptosis in MIAPaCa-2 and BxPC-3 cells. Western blotting and RT-PCR analysis revealed that the expression of clusterin was higher in gemcitabine -resistant MIAPaCa-2 cells, however, decreased significantly after pretreatment with OGX-011. Furthermore, the OGX-011 or combination of gemcitabine + OGX-011 decreased the gemcitabine -induced activation of pERK1/2. wt-pERK-re-expression decreased OGX-011+ gemcitabine -induced apoptosis. Finally, OGX-011 in combination with gemcitabine substantially decreased the in vivo tumor growth and promoted apoptosis. Taken together, clusterin confers gmcitabine resistance in pancreatic cancer cells. CONCLUSIONS: Knockdown of clusterin by OGX-011 transfection sensitizes pancreatic cancer cells to gemcitabine by inhibition of gemcitabine -induced clusterin-pERK1/2 activation.     

ZSTK474, a PI3K inhibitor, suppresses proliferation and sensitizes human pancreatic adenocarcinoma cells to gemcitabine

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is important in cell proliferation and survival, and it is frequently and aberrantly activated in pancreatic adenocarcinoma. Potential anti-tumor effect(s) of ZSTK474, a PI3K/Akt inhibitor, together with a key clinically relevant anti-tumor agent, gemcitabine (GEM), have been reported in a human pancreatic cancer xenograft mouse model. However, the precise molecular mechanism of these anti-tumor effects has not been well elucidated. In this study, we investigated the molecular mechanism of GEM plus ZSTK474 in reducing tumor cell survival in human pancreatic cancer cell lines. Our study showed that ZSTK474 inhibited cell growth by arresting cells at the G1 phase and by inducing apoptosis. ZSTK474 also inhibited the phosphorylation of Akt, GSK3β and BAD. The combination of GEM and ZSTK474 demonstrated synergistic anti-tumor effects on pancreatic cancer cells in both transient (3 days) and long-term (14 days) clonogenic assays. Thus, we elucidated the potential molecular mechanism leading to the enhanced anti-tumor effect when GEM and ZSTK474 are combined in treatment.     

Overexpression of Bax sensitizes human pancreatic cancer cells to apoptosis induced by chemotherapeutic agents

PURPOSE: Bax plays an important role in the regulation of apoptosis induced by chemotherapy and other stimuli. We therefore investigated the role of Bax in drug-induced apoptosis in human pancreatic cancer cells. METHOD: A tetracycline-inducible retroviral expression vector bearing the human bax-alpha gene was constructed. ASPC-1 cells were stably infected with this vector. The sensitivity of the transformed cell line to gemcitabine and 5-Fu was assessed. RESULTS: Western blots revealed that Bax expression was enhanced in these cells by the tetracycline analogue doxycycline. Enhanced expression of Bax itself did not inhibit the growth rate of infected cells and did not influence expression of Bcl-2 and Bcl-xL. However, it significantly increased the sensitivity of cells to the chemotherapeutic drugs gemcitabine and 5-Fu. These drugs also activated caspase-8 and caspase-3 by up to ninefold. Caspase activation and/or an imbalance in Bax and Bcl-2/Bcl-xL expression may be the reasons for the augmentation of cytotoxicity by these drugs. CONCLUSIONS: The findings suggest that enhanced Bax expression may have therapeutic application in enhancing the efficacy of chemotherapy in pancreatic cancers.     

Hypoxia increases resistance of human pancreatic cancer cells to apoptosis induced by gemcitabine.

PURPOSE: Hypoxia, frequently found in the center of solid tumor, is associated with resistance to chemotherapy by activation of signaling pathways that regulate cell pro-liferation, angiogenesis, and apoptosis. We determined whether hypoxia can increase the resistance of human pancreatic carcinoma cells to gemcitabine-induced apoptosis by activation of phosphatidylinositol 3'-kinase (PI3K)/Akt, MEK/mitogen-activated protein kinase (extracellular signal-regulated kinase) [MAPK(Erk) kinase (MEK)], and nuclear factor kappa B (NF-kappa B) signaling pathways. EXPERIMENTAL DESIGN: We evaluated the phosphorylation of Akt and MAPK(Erk), DNA binding activity of NF-kappa B, and apoptosis induced by gemcitabine in L3.6pl human pancreatic cancer cells under normoxic and hypoxic conditions. We then examined the effects of the PI3K inhibitor LY294002, MEK inhibitor U0126, and the epidermal growth factor receptor tyrosine kinase inhibitor PKI 166 on these signaling pathways and induction of apoptosis. RESULTS: Hypoxic conditions increased phosphorylation of Akt and MAPK(Erk) and NF-kappa B DNA binding activity in L3.6pl cells. The activation of Akt and NF-kappa B was prevented by LY294002, whereas the activity of MAPK(Erk), but not NF-kappa B, was inhibited by U0126. The increased activation of Akt, NF-kappa B, and MAPK(Erk) was inhibited by PKI 166. Under hypoxic conditions, L3.6pl cells were resistant to apoptosis induced by gemcitabine. The addition of LY294002 or PKI 166 abrogated cell resistance to gemcitabine, whereas U0126 only partially decreased this resistance. CONCLUSIONS: These data demonstrate that hypoxia can induce resistance of pancreatic cancer cells to gemcitabine mainly through the PI3K/Akt/NF-kappa B pathways and partially through the MAPK(Erk) signaling pathway. Because PKI 166 prevented the activation of PI3K/Akt/NF-kappa B and MAPK(Erk) pathways, the combination of this tyrosine kinase inhibitor with gemcitabine should be an effective therapy for pancreatic cancer.     

吉西他滨对肺癌细胞凋亡及PI3K/AKT信号通路的影响

目的探讨吉西他滨对肺癌细胞凋亡及PI3K/AKT信号通路的影响。方法选取对数生长期的肺癌NCI-H292细胞随机分为吉西他滨组、阿霉素组和对照组,分别采用7μmol/L的吉西他滨、阿霉素与生理盐水处理,采用CCK-8法检测细胞增殖,Transwell小室检测细胞迁移与侵袭,Annexin V-PI双标记法检测细胞凋亡,Western blot实验检测PI3K和AKT蛋白表达。结果细胞处理后24h和48h,吉西他滨组和阿霉素组的细胞增殖指数均低于对照组,吉西他滨组低于阿霉素组,差异均有统计学意义(均P <0.05)。细胞处理后24h和48h,吉西他滨组和阿霉素组的细胞迁移与侵袭指数均低于对照组,吉西他滨组低于阿霉素组,差异均有统计学意义(均P <0.05)。细胞处理后24h和48h,吉西他滨组和阿霉素组的细胞凋亡指数均高于对照组,吉西他滨组高于阿霉素组,差异均有统计学意义(均P <0.05)。细胞处理后24h和48h,吉西他滨组和阿霉素组PI3K和AKT蛋白表达水平均低于对照组,吉西他滨组低于阿霉素组,差异均有统计学意义(均P <0.05)。结论吉西他滨可促进肺癌...     

硼替佐米对胰腺癌细胞增殖、凋亡及PI3K/Akt通路的影响

目的:探讨硼替佐米（BTZ）对胰腺癌细胞增殖、凋亡及PI3K/Akt通路的影响。方法:体外培养人胰腺癌细胞株PANC-1细胞,分别给予硼替佐米（0,2,10,50,250 nmol/L）作用24 h,采用MTT法检测PANC-1细胞活力,采用Annexin V/PI双染法检测细胞凋亡情况,采用流式细胞术检测细胞周期,采用Western blot检测细胞凋亡及PI3K/Akt通路相关蛋白表达情况。结果:与0 nmol/L硼替佐米相比,不同浓度硼替佐米处理后,PANC-1细胞生长抑制率均显著升高（P＜0.05）,G0/G1期细胞比例均显著升高（P＜0.05）,细胞凋亡率显著升高（P＜0.05）,细胞中cleaved-caspase-3、Bax蛋白表达增高（P＜0.05）,Bcl-2、PI3K、p-Akt蛋白表达降低（P＜0.05）,且呈剂量依赖性;裸鼠成瘤实验中,不同浓度硼替佐米作用后,肿瘤瘤体质量显著降低（P＜0.05）,且呈剂量依赖性。结论:硼替佐米能抑制胰腺癌细胞PANC-1增殖,诱导其凋亡,推测硼替佐米可能通过调节PI3K/Akt通路,激活凋亡蛋白基因表达,抑制抗凋亡蛋白基因的表达,诱导PANC-1细胞凋亡。     

红花多糖抑制PI3K/Akt信号通路诱导人胃癌细胞凋亡的研究

目的 探讨红花多糖通过抑制PI3K/Akt信号通路调控胃癌细胞凋亡的机制。方法 MTT比色法观察SPS对人胃癌SGC-7901细胞体外增殖的抑制作用,流式细胞仪(FCM)分析细胞凋亡,实时荧光定量RT-PCR法和Western Blot法检测蛋白激酶B(Akt)基因及蛋白的表达情况。结果 红花多糖在一定范围内以剂量依赖方式和时间依赖方式抑制SGC-7901胃癌细胞生长。流式细胞仪检测,SGC-7901细胞经红花多糖处理24 h,其早期凋亡率、细胞坏死或晚期凋亡率显著增加,呈现明显的剂量依赖性。Real-time PCR和Western Blot检测发现,SPS处理的细胞Akt基因及蛋白表达量明显下降。结论 红花多糖对人胃癌SGC-7901细胞体外增殖具有明显的抑制作用,该抑制作用具有一定的时间依赖性和剂量依赖性;红花多糖能够下调Akt mRNA表达,降低Akt和p-Akt蛋白的表达量,抑制Akt通路发挥抗肿瘤作用。     

Survivin downregulation by siRNA sensitizes human hepatoma cells to TRAIL-induced apoptosis

Survivin, an anti-apoptotic protein, is abundantly expressed in a variety of cancer cells, including hepatoma cells, resulting in the resistance of these cells to various apoptotic stimuli. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known to induce cancer cell-specific apoptosis, but hepatoma cells are resistant to TRAIL-induced apoptosis. In the present study, we have examined whether the downregulation of survivin by short interfering RNA (siRNA) promotes spontaneous or TRAIL-induced apoptosis in Huh-7 human hepatoma cells. Survivin siRNA transfection downregulated the expression of survivin in Huh-7 cells and reduced cell viability by 20% through inducing spontaneous apoptosis. TRAIL (1 to 2 ng/ml) only slightly induced apoptosis in Huh-7 cells; however, survivin siRNA transfection apparently enhanced TRAIL-induced apoptosis. These results suggest that the level of survivin is linked to the susceptibility of Huh-7 cells to TRAIL. It is possible that survivin downregulation by siRNA combined with TRAIL administration may provide a new therapeutic strategy against hepatoma.     

HOXA10 expression induced by Abl kinase inhibitors enhanced apoptosis through PI3K pathway in CML cells

Chronic myelogenous leukemia is characterized by the reciprocal chromosomal translocation (9;22), which generates a novel fusion gene, BCR-ABL. Bcr-Abl-expressing leukemia cells are highly resistant to apoptosis. Imatinib an Abl kinase inhibitor, is a highly effective agent for patients with CML. However, a small percentage of these patients and most advanced-phase patients relapse on imatinib therapy. It is poorly understood whether the Abl kinase inhibitors are able to eradicate CML progenitor or stem cells. In this study, we investigated the role of HOXA10 in CML cell lines and the hematopoietic progenitor cells derived from CML patients, and whether the regulation of HOXA10 eradicates Bcr-Abl(+) hematopoietic stem/progenitor cells. The Abl kinase inhibitors and PI3K inhibitor, LY294002, induced the expression of HOXA10, and it enhanced apoptosis in CML cells. Moreover, the reduction of HOXA10 expression by siRNA in CML cells inhibited apoptosis by treatment with the Abl kinase inhibitors and LY294002. These results revealed that HOXA10 had an important role in induction of apoptosis by the Abl kinase inhibitors in CML cells. Finally, we showed that the inhibition of HOXA10 expression by siRNA increased the numbers of CFU-GEMM, BFU-E, and CFU-GM when the cells were treated with the combination of BMS354825 and LY294002 compared to control cells, and HOXA10 played a critical role in the committed colony-formation in CML. This study shows for the first time that the Abl kinase inhibitor and LY294002 induced HOXA10, and HOXA10 had an important role in apoptosis or cell growth inhibition in CML cells in vitro.     

Malignant ascites protect against TRAIL-induced apoptosis by activating the PI3K/Akt pathway in human ovarian carcinoma cells

Ascites are commonly found in ovarian cancer patients with advanced disease and are rich in cellular components and growth-promoting factors. The purpose of this study was to assess the effect of malignant ascites on TRAIL-induced apoptosis. We demonstrate that malignant ascites obtained from women with advanced ovarian cancer protect tumor cells from TRAIL- and FasL-induced apoptosis but not against cisplatin-induced apoptosis. This antiapoptotic effect was consistently found among different malignant ascites while nonmalignant peritoneal fluids or conditioned medium from TRAIL-resistant cells failed to protect tumor cells against TRAIL killing. Malignant ascites strongly inhibits TRAIL-induced caspase-3 activation and PARP cleavage. Furthermore, ascites activate PI3K and its downstream target Akt and increases c-FLIP(S) protein levels without affecting ERK phosphorylation status. The antiapoptotic effect of malignant ascites is abrogated by the inhibition of PI3K with LY294002, by a specific inhibitor of Akt and by Akt siRNA. We further show that the pro-survival effect of ascites can be suppressed by down-regulation of c-FLIP(S). Our data indicate that malignant effusions protect against TRAIL-induced apoptosis by activating the PI3K/Akt pathway. These findings demonstrate that the tumor microenvironment may contribute to the resistance of ovarian cancer cells to death receptor-induced apoptosis.     

Activation of IL-8 via PI3K/Akt-dependent pathway is involved in leptin-mediated epithelial-mesenchymal transition in human breast cancer cells

Background Information: Previous studies have revealed that leptin may be involved in epithelial-mesenchymal transition (EMT), a crucial initiator of cancer progression to facilitate metastatic cascade, increase tumor recurrence, and ultimately cause poor prognosis. However, the underlying mechanism remains unclear. The aim of our present study was to investigate the effect of leptin on EMT of breast cancer cells and the underlying mechanism. Results: Our data demonstrated that leptin significantly increased the phosphorylation of STAT3, Akt, and ERK1/2, elevated the expression of IL-8, and induced breast cancer cells to undergo EMT. The effect of leptin on IL-8 could visibly abolished by the inhibitor of PI3K {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. In addition, leptin-induced EMT of breast cancer cells was blocked by anti-IL-8 antibodies. Examination of the expression of ObR, leptin, IL-8 and EMT-related biomarkers in patient specimens demonstrated that malignant breast carcinoma with lymph node metastases (LNM), which represents poor prognosis, expressed higher levels of ObR, leptin, IL-8 than other types of breast cancer, and displayed more obvious EMT transversion. In vivo xenograft experiment revealed that leptin signally promoted tumor growth and metastasis and increased the expressions of IL-8 and EMT-related biomarkers. Conclusions: Our results support that leptin-induced EMT in breast cancer cells requires IL-8 activation via the PI3K/Akt signal pathway.     

PDCD4促进吉西他滨诱导胰腺癌细胞凋亡的实验研究

目的:研究程序性细胞死亡因子4（programmed cell death 4,PDCD4）在吉西他滨诱导胰腺癌细胞凋亡中的作用。方法:用吉西他滨处理胰腺癌细胞PANC-1,荧光定量PCR和Western blot分别检测胰腺癌细胞中PDCD4的表达变化。PANC-1细胞感染PDCD4-pGC-Fu-GFP重组慢病毒和对照pGC-Fu-GFP重组慢病毒,荧光定量PCR和Western blot检测过表达效果。用吉西他滨处理过表达PDCD4的PANC-1细胞,MTT测定细胞增殖,克隆形成实验测定细胞克隆能力,流式细胞术测定细胞凋亡,Western blot检测细胞中剪切的Caspase-3（Cleaved Caspase-3）、剪切的Caspase-9（Cleaved Caspase-9）蛋白水平和胞浆、线粒体中细胞色素C（Cytochrome C）蛋白水平。结果:吉西他滨处理后的PANC-1细胞中PDCD4 mRNA和蛋白水平均明显升高。吉西他滨处理和过表达PDCD4的PANC-1细胞增殖、克隆形成能力明显降低,细胞凋亡率明显升高,细胞中Cleaved Caspase-3、Cleaved Caspase-9蛋白水平升高,胞浆中Cytochrome C蛋白水平也升高,线粒体中Cytochrome C蛋白水平降低。吉西他滨处理过表达PDCD4的PANC-1细胞增殖能力、克隆形成能力降低更多,细胞凋亡率更高,细胞中Cleaved Caspase-3、Cleaved Caspase-9蛋白水平也更高,胞浆中Cytochrome C蛋白水平更高,线粒体中Cytochrome C蛋白水平更低。结论:吉西他滨通过上调PDCD4表达水平激活线粒体途径诱导胰腺癌细胞凋亡。     

Licochalcone A induces autophagy through PI3K/Akt/mTOR inactivation and autophagy suppression enhances Licochalcone A-induced apoptosis of human cervical cancer cells

The use of dietary bioactive compounds in chemoprevention can potentially reverse, suppress, or even prevent cancer progression. However, the effects of licochalcone A (LicA) on apoptosis and autophagy in cervical cancer cells have not yet been clearly elucidated. In this study, LicA treatment was found to significantly induce the apoptotic and autophagic capacities of cervical cancer cells in vitro and in vivo. MTT assay results showed dose- and time-dependent cytotoxicity in four cervical cancer cell lines treated with LicA. We found that LicA induced mitochondria-dependent apoptosis in SiHa cells, with decreasing Bcl-2 expression. LicA also induced autophagy effects were examined by identifying accumulation of Atg5, Atg7, Atg12 and microtubule-associated protein 1 light chain 3 (LC3)-II. Treatment with autophagy-specific inhibitors (3-methyladenine and bafilomycin A1) enhanced LicA-induced apoptosis. In addition, we suggested the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of mTOR pathway by LicA. Furthermore, the inhibition of PI3K/Akt by {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002/si-Akt or of mTOR by rapamycin augmented LicA-induced apoptosis and autophagy. Finally, the in vivo mice bearing a SiHa xenograft, LicA dosed at 10 or 20 mg/kg significantly inhibited tumor growth. Our findings demonstrate the chemotherapeutic potential of LicA for treatment of human cervical cancer.     

PI3K/Akt抑制剂渥曼青霉素对白血病细胞增殖和凋亡的影响

Objective  

We studied the effects of Wortmannin (WM) on the proliferation and apoptosis of leukemia cells, and explore the possible mechanisms.     

白花丹醌通过CXCL8/PI3K/AKT糖酵解通路抑制结肠癌细胞增殖、促进凋亡

目的:观察白花丹醌对结肠癌细胞Caco-2增殖、凋亡的影响,探究其潜在的作用机制。方法:运用CCK8法、流式细胞术检测不同浓度白花丹醌（4、8、12 μmol/L）处理的Caco-2细胞的增殖抑制率、凋亡率。不做任何处理的Caco-2细胞设为Control;脂质体法将si-NC组（转染si-NC）、si-CXCL8组（转染si-CXCL8）转染至Caco-2细胞;8 μmol/L的白花丹醌与0.5%DMSO处理的Caco-2细胞设为8 μmol/L+DMSO组;8 μmol/L的白花丹醌分别与z-VAD-FMK、740Y-P处理的Caco-2细胞设为8 μmol/L+z-VAD-FMK组、8 μmol/L+740Y-P组。RT-qPCR、Western blot实验检测细胞中CXCL8的mRNA、蛋白表达,CXCL8、M2-型丙酮酸激酶（M2 pyruvate kinase, PKM2）、L-乳酸脱氢酶A（lactate dehydrogenase A,LDHA）、人α-烯醇化酶(apha-enolase,ENO1)、葡萄糖磷酸异构酶（glucose phosphate isomerase,GPI）、磷酸化磷脂酰肌醇3激酶（phosphorylated phosphatidylinositol 3 kinase,p-PI3K）、磷酸化蛋白激酶B（phosphorylated protein kinase B,p-AKT）的蛋白表达。结果:与Control组相比,白花丹醌（4、8、12 μmol/L）呈浓度依赖性促进Caco-2细胞增殖抑制率、凋亡率升高,抑制CXCL8的mRNA和蛋白表达。与8 μmol/L+DMSO组相比,8 μmol/L+z-VAD-FMK组细胞的增殖抑制率、凋亡率明显降低,CXCL8的mRNA和蛋白表达明显升高（P＜0.05）。白花丹醌（4、8、12 μmol/L）呈浓度依赖性抑制PKM2、LDHA、p-PI3K、p-AKT的蛋白表达。si-CXCL8组PKM2、LDHA、p-PI3K、p-AKT的蛋白表达明显低于si-NC组。740Y-P明显减弱白花丹醌对Caco-2细胞增殖抑制率和凋亡率的促进作用。结论:白花丹醌抑制结肠癌细胞增殖,促进凋亡,其潜在的作用机制与CXCL8/PI3K/AKT糖酵解通路有关。