β-Elemene Effectively Suppresses the Growth and Survival of Both Platinum-sensitive and -resistant Ovarian Tumor Cells

The development of cisplatin drug resistance remains a chief concern in ovarian cancer chemotherapy. β-Elemene is a natural plant product with broad-spectrum antitumor activity towards many types of carcinomas. This study aimed to define the biological and therapeutic significance of β-elemene in chemoresistant ovarian cancer. In the present study, β-elemene significantly inhibited cell growth and proliferation of both the cisplatin-sensitive human ovarian cancer cell line A2780 and its cisplatin-resistant counterpart A2780/CP. β-Elemene also suppressed the growth of several other chemosensitive and chemoresistant ovarian cancer cell lines, including ES-2, MCAS, OVCAR-3, and SKOV-3, with the half maximal inhibitory concentration (IC(50)) values ranging from 54 to 78 μg/ml. In contrast, the IC(50) values of β-elemene for the human ovarian epithelial cell lines IOSE-386 and IOSE-397 were 110 and 114 μg/ml, respectively, which are almost two-fold those for the ovarian cancer cell lines. Cell cycle analysis demonstrated that β-elemene induced a persistent block of cell cycle progression at the G(2)/M phase in A2780 and A2780/CP cells. This was mediated by alterations in cyclin and cyclin-dependent kinase expression, including the down-regulation of CDC2, cyclin A, and cyclin B1, and the up-regulation of p21(WAF1/CIP1) and p53 proteins. Moreover, β-elemene triggered apoptosis and irreversible cell death in both sensitive and resistant ovarian cancer cells via the activation of caspase-3, -8 and 9; the loss of mitochondrial membrane potential (δΨm); the release of cytochrome c into the cytosol; and changes in the expression of BCL-2 family proteins. All of these molecular changes were associated with β-elemene-induced growth inhibition and cell death of ovarian cancer cells. Our results demonstrate that β-elemene has antitumor activity against both platinum-sensitive and resistant ovarian cancer cells, and thus has the potential for development as a chemotherapeutic agent for cisplatin-resistant ovarian cancer.     

Growth inhibitory effect of D-allose on human ovarian carcinoma cells in vitro

BACKGROUND: D-allose is a rare sugar found in nature and, because of its very limited amount and of the high cost associated with its synthesis, its physiological functions remain virtually unknown. The aim of the current study was to investigate the effect of D-allose on the proliferation of human ovarian carcinoma cells in vitro. MATERIALS AND METHODS: Human ovarian carcinoma cells (OVCAR-3 cell line) were exposed to rare sugars including D-allose, D-altrose, D-psicose and D-talitol. Cell growth was evaluated by MTT assay. Cell cycle analysis was carried out by flow cytometric assay. The expression of cell cycle regulatory proteins was determined by Western blot analysis. TUNEL assay was employed for the detection of apoptotic cells. RESULTS: D-allose had a significant inhibitory effect on ovarian cancer cell proliferation in a dose-dependent manner, and caused a moderate G2/M arrest in the cell cycle, up-regulation of Cdk inhibitors p21 and p27 levels, and the induction of apoptosis in OVCAR-3 cells. CONCLUSION: Our results show, for the first time, that D-allose inhibits the growth of ovarian carcinoma cells in vitro. Although the exact mechanisms remain unclear, these findings suggest that D-allose possesses a novel inhibitory property on ovarian carcinoma cell proliferation, and may represent a new class of compounds with possible therapeutic potential.     

The phosphatidylinositol 3-kinase/AKT signal transduction pathway plays a critical role in the expression of p21WAF1/CIP1/SDI1 induced by cisplatin and paclitaxel

The cyclin-dependent kinase inhibitor p21WAF1/CIP1/SD11 (p21) plays a crucial role in DNA repair, cell differentiation, and apoptosis through regulation of the cell cycle. A2780 human ovarian carcinoma cells, which are sensitive to cisplatin and paclitaxel, express wild-type p53 and exhibit a p53-mediated increase in p21 in response to the chemotherapeutic agents. Here, we demonstrate that phosphatidylinositol 3-kinase (PI3K) and its downstream targets serine/threonine kinases AKT1 and AKT2 (AKT), are required for the full induction of p21 in A2780 cells treated with cisplatin or paclitaxel. Inactivation of the PI3K/AKT signal transduction pathway either by its specific inhibitor LY294002 or by expression of dominant negative AKT inhibited p21 expression but had no inhibitory effect on the expression of the proapoptotic protein BAX by cisplatin and paclitaxel treatment. In addition, overexpression of wild-type or constitutively active AKT in A2780 cells sustained the regulation of p21 induction or increased the level of p21 expression, respectively. Experiments with additional ovarian carcinoma cell lines revealed that PI3K is involved in the expression of p21 induced by cisplatin or paclitaxel in OVCAR-10 cells, which have wild-type p53, but not in OVCAR-5 cells, which lack functional p53. These data indicate that the PI3K/AKT signal transduction pathway mediates p21 expression and suggest that this pathway contributes to cell cycle regulation promoted by p53 in response to drug-induced stress. However, inactivation of PI3K/AKT signaling did not result in significant alteration of the drug sensitivity of A2780 cells, suggesting that the cell death induced by cisplatin or paclitaxel proceeds independently of cell protective effects of PI3K and AKT.     

Caspase-dependent and -independent suppression of apoptosis by monoHER in Doxorubicin treated cells

Doxorubicin (DOX) is an antitumour agent for different types of cancer, but the dose-related cardiotoxicity limits its clinical use. To prevent this side effect we have developed the flavonoid monohydroxyethylrutoside (monoHER), a promising protective agent, which did not interfere with the antitumour activity of DOX. To obtain more insight in the mechanism underlying the selective protective effects of monoHER, we investigated whether monoHER (1 mM) affects DOX-induced apoptosis in neonatal rat cardiac myocytes (NeRCaMs), human endothelial cells (HUVECs) and the ovarian cancer cell lines A2780 and OVCAR-3. DOX-induced cell death was effectively reduced by monoHER in heart, endothelial and A2780 cells. OVCAR-3 cells were highly resistant to DOX-induced apoptosis. Experiments with the caspase-inhibitor zVAD-fmk showed that DOX-induced apoptosis was caspase-dependent in HUVECs and A2780 cells, whereas caspase-independent mechanisms seem to be important in NeRCaMs. MonoHER suppressed DOX-dependent activation of the mitochondrial apoptotic pathway in normal and A2780 cells as illustrated by p53 accumulation and activation of caspase-9 and -3 cleavage. Thus, monoHER acts by suppressing the activation of molecular mechanisms that mediate either caspase-dependent or -independent cell death. In light of the current work and our previous studies, the use of clinically achievable concentrations of monoHER has no influence on the antitumour activity of DOX whereas higher concentrations as used in the present study could influence the antitumour activity of DOX.     

葡萄糖对卵巢癌细胞生长增殖影响体外研究

目的 葡萄糖是维持肿瘤细胞存活的重要能量来源,有关研究表明低糖与无糖条件有可能抑制肿瘤细胞生长,成为潜在的肿瘤治疗方式.本研究通过给予不同浓度葡萄糖刺激SKOV3与A2780卵巢癌细胞系,分析其细胞增殖、细胞周期与细胞凋亡的改变,探讨葡萄糖对卵巢癌细胞生长增殖的影响.方法 在体外配制含不同葡萄糖浓度(0、2.5、 5.5、 25.0 mmol/L)的培养基,分别模拟无糖、低血糖、正常血糖及高血糖水平的体内环境,观察不同葡萄糖浓度对卵巢癌细胞的增殖、凋亡与细胞周期的影响.结果 高糖促进卵巢癌细胞SKOV3和A2780的增殖,干预48 h后,增殖幅度约为无糖组的1.841~1.942倍;低糖与无糖条件诱导卵巢癌细胞发生G1期阻滞,与高糖组相比,SKOV3细胞G1期比例以(40.699±1.131)%增加至(58.619±2.643)%,A2780细胞以(46.348±2.150)%增加至(54.770±2.475)%;低糖与无糖条件亦诱导细胞凋亡,SKOV3与A2780细胞无糖组中凋亡细胞比例分别为(14.015±0.827)%和(12.930±1.127)%.结论 本研究通过探讨葡萄糖对卵巢癌细胞生长与增殖的影响,证明低糖与无糖条件诱导卵巢癌细胞发生G1期阻滞、细胞凋亡并抑制其生长增殖.若进一步给予相应葡萄糖抑制剂干预,可能为卵巢癌的临床治疗提供新思路.     

Adenosine induces cell cycle arrest and apoptosis via cyclinD1/Cdk4 and Bcl-2/Bax pathways in human ovarian cancer cell line OVCAR-3

Adenosine is a regulatory molecule with widespread physiological effects in almost every cells and acts as a potent regulator of cell growth. Adenosine has been shown to inhibit cell growth and induce apoptosis in the several cancer cells via caspase activation and Bcl-2/Bax pathway. The present study was designed to understand the mechanism underlying adenosine-induced apoptosis in the OVCAR-3 human ovarian cancer cells. MTT viability, BrdU and cell counting assays were used to study the cell proliferation effect of adenosine in presence of adenosine deaminase inhibitor and the nucleoside transporter inhibitor. Cell cycle analysis, propidium iodide and annexin V staining, caspase-3 activity assay, cyclinD1, Cdk4, Bcl-2 and Bax protein expressions were assessed to detect apoptosis. Adenosine significantly inhibited cell proliferation in a concentration-dependent manner in OVCAR-3 cell line. Adenosine induced cell cycle arrest in G0/G1 phase via Cdk4/cyclinD1-mediated pathway. Adenosine induced apoptosis, which was determined by Annexin V-FITC staining and increased sub-G1 population. Moreover, down-regulation of Bcl-2 protein expression, up-regulation of Bax protein expression and activation of caspase-3 were observed in response to adenosine treatment. The results of this study suggest that extracellular adenosine induced G1 cell cycle arrest and apoptosis in ovarian cancer cells via cyclinD1/ Cdk4 and Bcl-2/Bax pathways and caspase-3 activation. These data might suggest that adenosine could be used as an agent for the treatment of ovarian cancer.     

siRNA下调LSD1基因对卵巢癌OVCAR-3细胞增殖和周期的影响

目的应用小分子干扰RNA（small interfering RNA,siRNA）抑制赖氨酸特异性组蛋白去甲基化酶1（lysine specific demethylase 1,LSD1）基因的表达,探讨其对卵巢癌OVCAR-3细胞增殖和生长周期的影响。方法采用脂质体介导法将LSD1-siRNA转染卵巢癌OVCAR-3细胞;实时荧光定量PCR（RFQ-PCR）和Western blot法检测基因的表达;MTT法检测细胞增殖能力;FCM分析细胞周期。结果成功转染LSD1-siRNA后,OVCAR-3细胞中LSD1 mRNA和蛋白表达均明显下降;细胞增殖明显抑制;G₂/M期细胞比例增加。结论 LSD1-siRNA可显著下调LSD1基因在卵巢癌OVCAR-3细胞中的表达水平,在一定程度上抑制卵巢癌细胞的增殖,导致细胞周期阻滞。     

The Effect of the MDM2-p53 Loop on the Sensitivity of Ovarian Cancer Cells to Cisplatin

OBJECTIVE To explore whether MDM2 transfection can alter the MDM2-p53 autoregulatory feedback loop so as to change the sensitivity of ovarian cancer cell lines to cisplatin. METHODS The ovarian cancer cell line A2780 expressing wild-type P53 and the ovarian cancer cell line SKOV-3 with the p53 null type were stably transfected with pCMV-MDM2 or pCMV as a control. The blocked expression of P53 was determined by Western blots. Cytotoxicity was assessed using the MTT assay and the trypan blue exclusion assay. Flow cytometry was used to detect changes in the cell cycle and removal of platinum -DNA adducts was measured by atomic absorption spec-troscopy. RESULTS (1) Parental A2780 and A2780-V cells (IC50= 15.14±1.39 μmol) have similar cisplatin sensitivities, whereas sensitivity to cisplatin in A2780-M cells (IC50=7.98±1.32 μmol) was 2 to 3 fold greater (P=0.001). The trypan blue exclusion assay demonstrated that cisplatin killed a higher percentage of A2780-M cells compared to A2780-V cells. There was no significant change following MDM2 transfection in SKOV-3 cells. (2) After cisplatin treatment, A2780-M cells showed a pronounced S-phase arrest, however, A2780 cells with the intact wild-type P53, arrested primarily at the G2/M transition. (3) Platinum uptake was similar for all of the A2780 cell lines after ciaplatin treatment, but the removal of plat-inum-DNA adducts was reduced in the A2780-M cells compared with A2780-V cells. CONCLUSION MDM2 increases cisplatin cytotoxicity in ovarian cancer cells by blocking the expression of p53 through the MDM2-p53 autoregulatory feedback loop.     

Combination effect of adenovirus-mediated pro-apoptotic bax gene transfer with cisplatin or paclitaxel treatment in ovarian cancer cell lines

To develop a novel therapeutic strategy for ovarian cancer, we constructed a recombinant adenovirus which highly expresses pro-apoptotic Bax protein and examined its therapeutic effect on a series of ovarian cancer cell lines: A2780, A2780/cDDP, OVCAR-3 and SK-OV-3. A recombinant adenovirus carrying the Bax-alpha gene (AxCALNKYbax) induced high expression of the Bax-alpha protein in all the cell lines. The cytotoxic effect of Bax was observed in three ovarian cancer cell lines: the per cent reduction in the number of cells was 40.0% for cisplatin-sensitive A2780, 50.0% for cisplatin-resistant A2780/cDDP, and 64.8% for marginally cisplatin-resistant OVCAR-3. In contrast, it was only 12.3% for cisplatin-resistant SK-OV-3. Cisplatin-resistant A2780/cDDP had a p53 mutation and exhibited attenuated Bax induction after cisplatin treatment, which may explain why supplementation of Bax was effective in this chemoresistant ovarian cancer. Combination with cisplatin or paclitaxel enhanced the cytotoxic effect of Bax induction in all but one cell line including cisplatin-resistant A2780/cDDP. It appears that adenovirus-mediated Bax induction, with or without combination with conventional chemotherapy, useful strategy for the treatment of ovarian cancer.     

Induction of p53-dependent and p53-independent cellular responses by topoisomerase 1 inhibitors.

We have previously shown that loss of p53 function in A2780 human ovarian adenocarcinoma cells confers increased clonogenic resistance to several DNA-damaging agents, but not to taxol or camptothecin. We have now extended these studies, comparing wild-type p53-expressing A2780 cells with isogenic derivatives transfected with a dominant negative mutant (143; val to ala) p53. We show that, as well as retaining equivalent clonogenic sensitivity to camptothecin, mutant p53 transfectants of A2780 cells do not acquire significantly increased resistance to the camptothecin analogues topotecan and SN-38, the active metabolite of CPT-11. Compared with vector-alone transfectants they are, however, relatively (2.2-fold) resistant to GI 147211, a further camptothecin analogue undergoing clinical trial. Treatment of A2780 with camptothecin and each analogue produces an increase, maximal at 24-48 h after drug exposure, of cells in the G2/M phase of the cell cycle and a decrease in both G1 and S-phase cells. The G2 arrest is independent of p53 function for camptothecin and the three analogues. All four compounds can induce apoptosis in A2780, which is reduced in mutant p53 transfectants, as measured using the terminal DNA transferase-mediated b-d UTP nick end labelling (TUNEL) assay. Thus, although p53-dependent apoptosis is induced by camptothecin, topotecan and SN-38 in this human ovarian carcinoma cell line, these drugs induce p53-independent death, as measured by clonogenic assay.     

Driving p53 response to Bax activation greatly enhances sensitivity to taxol by inducing massive apoptosis

The proapoptotic gene bax is one of the downstream effectors of p53. The p53 binding site in the bax promoter is less responsive to p53 than the one in the growth arrest mediating gene p21. We introduced the bax gene under the control of 13 copies of a strong p53 responsive element into two ovarian cancer cell lines. The clones expressing bax under the control of p53 obtained from the wild-type (wt) p53-expressing cell line A2780 were much more sensitive (500- to 1000-fold) to the anticancer agent taxol than the parent cell line, with a higher percentage of cells undergoing apoptosis after drug treatment that was clearly p53-dependent and bax-mediated. Xenografts established in nude mice from one selected clone (A2780/C3) were more responsive to taxol than the parental line and the apoptotic response of A2780/C3 tumors was also increased after treatment. Introduction of the same plasmid into the p53 null SKOV3 cell line did not alter the sensitivity to taxol or the induction of apoptosis. In conclusion, driving the p53 response (after taxol treatment) by activating the bax gene rather than the p21 gene results in induction of massive apoptosis, in vitro and in vivo, and greatly enhances sensitivity to the drug.     

Antiproliferative and proapoptotic activities of triptolide (PG490), a natural product entering clinical trials, on primary cultures of human prostatic epithelial cells.

Interest in exploiting traditional medicines for prevention or treatment of cancer is increasing. Extracts from the herb Tripterygium wilfordii hook F have been used in China for centuries to treat immune-related disorders. Recently it was reported that triptolide (PG490), a purified compound from Tripterygium, possessed antitumor properties and induced apoptosis by p53-independent mechanisms in a variety of malignant cell lines. This property of triptolide attracted our attention because we have found that primary cultures of human prostatic epithelial cells derived from normal tissues and adenocarcinomas are in general extremely resistant to apoptosis. Furthermore, the function of wild-type p53 is impaired in these cells such that drugs that require p53 activity to induce cell death are ineffective. Therefore, the properties of triptolide and the recent approval of its water-soluble form (PG490-88) for entry into Phase I clinical trials suggested that this drug was a promising candidate to test for antitumor activity against prostate cells. Experiments presented here demonstrated that triptolide had dose-dependent effects on both normal and cancer-derived primary cultures of human prostatic epithelial cells. Low concentrations of triptolide inhibited cell proliferation and induced a senescence-like phenotype. Higher concentrations of triptolide induced apoptosis that was unexpectedly associated with nuclear accumulation of p53. Paradoxically, levels of the p53 target genes, p21(WAF1/CIP1) and hdm-2, were reduced, as was bcl-2. Our preclinical studies suggest that triptolide might be an effective preventive as well as therapeutic agent against prostate cancer and that triptolide may activate a functional p53 pathway in prostate cells.     

p53通路微小RNA在卵巢癌细胞和浆液性卵巢癌组织中的表达及意义

目的 探讨微小RNA (miRNA) miR-449a、miR-449b和miR-192家族是否与miR-34家族一样可作为p53通路成员,在卵巢癌中发挥作用.方法 以DNA损伤药物阿霉素处理p53野生型卵巢癌A2780细胞,采用Western blot法检测A2780细胞中p53蛋白的表达改变,采用实时定量PCR法检测激活p53后miR-449a/b、miR-34a、miR-34b、miR-34c、miR-192和miR-194的表达.在P53突变型卵巢癌SKOV3.ipl细胞中过表达miRNA,检测SKOV3.ipl细胞的细胞周期改变.采用实时定量PCR法检测miR-449a/b、miR-34a、miR-34b、miR-34c、miR-192和miR-194在正常输卵管以及不同分级分期的浆液性卵巢癌组织中的表达.结果 在阿霉素处理后24h,卵巢癌A2780细胞中p53蛋白的表达明显升高,miR-34b、miR-34c、miR-449a/b的表达约升高19 ～ 21倍,但miR-192和miR-194的表达未见明显变化.转染miR-449b和miR-34c后,SKOV3.ipl细胞出现G1期阻滞.miR-449a/b在浆液性卵巢癌组织中的表达改变与miR-34b和miR-34c基本平行,它们在高级别和晚期浆液性卵巢癌组织中的表达水平,显著低于正常输卵管组织以及低级别和早期浆液性卵巢癌组织;miR-192、miR-194和miR-34a在卵巢癌组织中的表达未发现明显的特征,在正常输卵管组织中的表达也明显低于miR-449a/b、miR-34b和miR-34c.结论 miR-449a/b与miR-34b、miR-34c作为抑癌基因,在p53通路中发挥协同作用,它们的功能缺失与浆液性卵巢癌的发生、发展密切相关.     

Triptolide induces Bcl-2 cleavage and mitochondria dependent apoptosis in p53-deficient HL-60 cells

Triptolide, a bioactive component of the Chinese medicinal herb Tripterygium wilfordii Hook F., induces p53-mediated apoptosis in cancer cells. This study demonstrated that triptolide activated an alternative p53-independent apoptotic pathway in HL-60 cells. In the absence of an intact p53 and without changing Bax level, at nM range triptolide induced apoptosis with concomitant DNA fragmentation, S phase cell cycle arrest, mitochondrial cytochrome c release and the activation of caspases. Besides, both caspases 8 and 9 were activated and the simultaneous inhibition of both was required to completely block triptolide's apoptotic effect. Importantly, triptolide induced the appearance of a truncated 23kD Bcl-2 which was inhibited by the general caspase inhibitor Z-VAD-FMK. In the MCF-7 cells that possessed the wild type p53 but lacked caspases 3, triptolide induced cell death with an increase in p53 but Bcl-2 remained unaltered. On the other hand, transfected cells overexpressing the 28kD Bcl-2 became more resistant to triptolide and upon triptolide treatment accumulated in the G(1) instead of S phase. After 36h treatment, triptolide activated JNK pathways, at the same time inactivated the ERK and p38 pathways. However, SP600125, a specific JNK inhibitor, could not inhibit the triptolide-mediated cleavage of caspase 3, indicated that activation of JNK might not be related to the apoptotic effects of triptolide. Our data suggest that in the absence of an intact p53 and without altering Bax level triptolide induces apoptosis activates a positive amplification loop involving caspase-mediated Bcl-2 cleavage/activation, mitochondrial cytochrome c release and further activation of caspases.     

EM012, a microtubule-interfering agent, inhibits the progression of multidrug-resistant human ovarian cancer both in cultured cells and in athymic nude mice

Drug resistance, in particular multidrug resistance, is a serious problem that impedes the effectiveness of chemotherapy. Multidrug resistance results mainly from an enhanced efflux of drugs by drug pumps located on the cell membrane such as P-glycoprotein. In the study reported here we showed that EM012, a microtubule-interfering agent, is a weak substrate for P-glycoprotein and inhibited the proliferation of A2780/ADR human ovarian cancer cells, which possess multidrug resistance due to P-glycoprotein overexpression. A2780/ADR cells treated with EM012 exhibited pronounced mitotic arrest, developed large multilobed nuclei, and eventually died through the initiation of apoptosis. Intraperitoneal treatment of A2780/ADR xenograft tumors in athymic nude mice with EM012 significantly inhibited tumor progression through triggering apoptosis and conferred an apparent survival advantage. Furthermore, EM012 treatment did not cause detectable toxicity to normal tissues. These findings suggest that EM012 may serve as a novel chemotherapeutic agent for the treatment of multidrug-resistant human ovarian cancer.     

蛋白激酶B调控的p53蛋白直接线粒体转移与卵巢癌细胞顺铂耐药的关系

目的 探讨蛋白激酶B(PKB,又称Akt)调控的p53蛋白直接线粒体转移在顺铂诱导的卵巢癌细胞凋亡中的作用及与卵巢癌顺铂耐药的关系.方法 应用Western blot检测顺铂作用前后卵巢癌顺铂敏感细胞OV2008、A2780s和顺铂耐药细胞C13*、A2780cp中线粒体和全细胞中p53含量.分离纯化线粒体,检测卵巢癌敏感细胞与耐药细胞p53直接线粒体作用的差异;应用Hoechst染色法检测卵巢癌细胞的凋亡率,将Akt1/2 siRNA导入耐药细胞C13*细胞中,观察p53线粒体转移作用和细胞凋亡率的改变.结果 顺铂能引起p53进入OV2008和A2780s细胞的线粒体中,但不能进入C13*和A2780cP细胞的线粒体.过度表达活化的Akt2能抑制p53进入A2780s细胞的线粒体;下调Akt后,可使p53进入C13*细胞的线粒体,同时C13*细胞对顺铂的敏感性增加.结论 顺铂能引起卵巢癌敏感细胞中p53转移至线粒体,Akt导致的卵巢癌化疗耐药在一定程度上是Akt对p53直接线粒体作用的抑制.下调Akt的表达能使卵巢癌化疗耐药细胞的p53直接线粒体作用增强,耐药性得到一定程度的逆转.

Abstract：

Objective To explore Akt-regulated direct p53 mitochondrial translocation in cisplatininduced apoptosis in ovarian cancer cells and the relationship between this and chemoresistance in ovarian cancer. Methods Chemosensitive ovarian cancer cell lines(0V2008 and A2780s) and chemoresistant cells(C13* and A2780cp) were treated with cisplatin and whole cell and mitochondrial p53 contents were determined by Western blot.The p53 accumulation in mitochondria was determined in purified mitochondrial fractions in cisplatin-sensitive and -resistant ovarian cancer cells.Akt1/2 siRNA were transfected into C13*cells.Cisplatin-induced apoptosis was measured by Hoechst staining and p53 translocation was determined by Western blot.ResultsCisplatin induced mitochondrial p53 accumulation and apoptosis in chemosensitive cells(P ＜0.05 ),but not in resistant cells(P ＞ 0.05 ).Over-expression of active Akt2 inhibited p53 directly translocate to mitochondria,and downregulation of Akt by Akt1/2 siRNA increased p53 mitochondrial accumulation and sensitize C13* cells to cisplatin treatment. Conclusions Cisplatin induces direct p53 mitochondrial accumulation in chemosensitive cells,and Akt confers resistance in ovarian cancer cells,in part,by regulating the direct action of p53 in mitochondrial death pathway.     

Oncolytic herpes simplex virus-1 lacking ICP34.5 induces p53-independent death and is efficacious against chemotherapy-resistant ovarian cancer.

Replication-restricted herpes simplex virus-1 (HSV-1) strains lacking ICP34.5 are emerging as powerful anticancer agents against several solid tumors including epithelial ovarian cancer (EOC). Although chemotherapy-resistant tumors would be likely candidates for treatment with HSV-1 mutants lacking ICP34.5, the efficacy of these mutants on such tumors is unknown. In the present study, we investigated whether chemotherapy resistance affects the response of ovarian cancer cells to HSV-R3616, an ICP34.5-deficient, replication-restricted HSV-1. Primary EOC cultures obtained from patients who varied in their responses to platinum/paclitaxel induction chemotherapy displayed similar sensitivity to HSV-R3616. Similarly, chemotherapy-sensitive ovarian cancer cells A2780 and PA-1, possessing wild-type p53, and their respective chemotherapy-resistant clones A2780/200CP, lacking p53 function, and PA-1/E6, permanently expressing the HPV E6 gene, were equally sensitive to HSV oncolysis. Because wild-type HSV can kill cells by apoptosis and nonapoptotic mechanisms, we investigated the involvement of apoptosis and the role of the p53 tumor suppressor gene in oncolysis induced by HSV-R3616. Infection of ovarian cancer cell lines by HSV-R3616 was followed by cell death via apoptosis or nonapoptotic mechanisms as noted by morphology, cell cycle analysis, and in situ TUNEL assay. p53 protein levels remained unchanged, and Bax protein levels decreased in cells possessing intact p53 and that mainly underwent HSV-induced apoptosis. Loss of p53 function did not affect the frequency or rate of apoptosis or the sensitivity of EOC cells to the oncolytic effect of HSV-R3616. These results suggest that recombinant HSV-1 lacking ICP34.5 is capable of killing ovarian cancer cells that lack p53 function, resist apoptosis, and/or are chemotherapy resistant. These data support the hypothesis that HSV-based oncolytic therapy may be efficacious in chemotherapy-resistant tumors, including tumors that are deficient in p53.     

miR-144-3p靶向zeb1调控卵巢癌细胞SKOV3的增殖和凋亡

目的:探讨miR-144-3p是否通过靶向E盒锌指结合蛋白1（zeb1）调控卵巢癌细胞SKOV3的增殖和凋亡。方法:qRT-PCR检测miR-144-3p在卵巢癌细胞和正常人卵巢上皮细胞中的表达差异。在卵巢癌细胞SKOV3中转染miR-144-3p mimics,MTT法测定细胞增殖,PI单染法检测细胞周期,Annexin V-FITC/PI双染法检测细胞凋亡,Western blot检测细胞中cyclinD1、p27、C-caspase-3蛋白表达。生物信息学软件预测miR-144-3p的靶基因可能为zeb1,荧光素酶报告系统鉴定其靶向关系。在卵巢癌细胞SKOV3中共转染miR-144-3p mimics、pcDNA3.1-zeb1,利用上述方法测定细胞增殖、周期和凋亡变化。结果:miR-144-3p在卵巢癌细胞中的表达水平低于正常人卵巢上皮细胞。转染miR-144-3p mimics后的卵巢癌细胞SKOV3增殖能力下降,细胞周期被阻滞在G1期,细胞凋亡增多,细胞中cyclinD1蛋白表达减少,p27、C-caspase-3蛋白表达增加。miR-144-3p靶向调控zeb1表达。pcDNA3.1-zeb1可以逆转miR-144-3p mimics对卵巢癌细胞增殖抑制、周期阻滞和凋亡促进作用。结论:miR-144-3p靶向zeb1抑制卵巢癌细胞SKOV3增殖并诱导细胞凋亡。     

Apoptotic effect of citrus fruit extract nobiletin on lung cancer cell line A549 in vitro and in vivo

Lung cancer is the leading cause for cancer-related death worldwide and the effectiveness of current treatments is very limited. Here we reported that Nobiletin, an effective component of citrus fruit, has antiproliferative activity on lung cancer cells both in vitro and in vivo. Cell viability and clonogenic assay showed that Nobiletin dose-dependently suppressed the proliferation of human lung adenocarcinoma cell line A549 cells, while has having a minimal effect on human umbilical vein endothelial cell line ECV-304 cells. DNA fragment assay and comet assay demonstrated that Nobiletin induced A549 cell apoptosis. Nobiletin-induced cell cycle arrest at G(2)/M phase was detected by Flow cytometric analysis. In addition, Western blot analysis revealed that A549 cells pretreated with Nobiletin showed decreased Bcl-2 and increased Bax protein expression, which were positively correlated with elevated expression of p53 compared to control. Furthermore, Nobiletin had overt inhibitory effect on the tumor growth in nude mice model was observed in vivo. Taken together, these results suggest that Nobiletin could induce p53-mediated cell cycle arrest and apoptosis via modulated the Bax:Bcl-2 protein ratio, is effective as a potent antitumor agent on lung tumors.