多聚乙烯基亚胺介导的卵巢特异性启动子调控下的自杀基因抑制卵巢癌细胞生长的体外研究

背景与目的目前基因治疗领域的关键技术问题是如何提高基因载体的转导效率和靶向性。近年来以一种新的多聚阳离子化合物—多聚乙烯基亚胺(polyethylenimine,PEI)作为载体为基因转移提供了一条有效的新思路。本研究应用PEI介导卵巢特异性启动子OSP-1调控下的自杀基因HSV-tk体外处理人卵巢癌细胞SKOV3,观察其抗瘤效应和靶向性。方法(1)将pGL3-Luc质粒分别介导多聚乙烯基亚胺PEI、脂质体DOTAP和裸DNA转染人卵巢癌细胞SKOV3,检测荧光素酶表达RLU(relativeluciferaseunit);(2)利用PEI将卵巢特异性启动子调控下的真核表达质粒pOSP1-HSVtk导入人卵巢癌细胞SKOV3、人肝癌细胞SMMC7721,应用MTT法测定更昔洛韦(ganciclovir,GCV)对两种肿瘤细胞的毒性;高效液相色谱法(highperformanceliquidchromatography,HPLC)检测GCV在SKOV3的细胞内代谢;流式细胞仪和末端脱氧核苷酸转移酶原位标记(TdT-mediateddUTPnickendlabeling,TUNEL)检测肿瘤细胞的凋亡。结果(1)PEI组的荧光素酶表达活性最高(187.35±6.48),与另两组相比(45.74±5.98,0.03±0.00),有显著性差异(P<0.01);(2)GCV对SKOV3细胞呈现明显的细胞毒性,对SMMC7721细胞没有产生细胞毒性;HPLC检测显示随着作用时间的延长,细胞内GCV水平逐渐下降;流式细胞仪显示转染pOSP1-HSVtk质粒的SKOV3细胞经GCV作用24、48、72h后,凋亡率分别为(8.42±0.76)%、(18.50±1.78)%、(34.80±3.46)%,呈明显的增高趋势;TUNEL检测SKOV3细胞可见大量凋亡细胞。结论多聚乙烯基亚胺介导卵巢特异性启动子调控下的自杀基因对卵巢癌有特异的体外杀伤作用,有助于提高基因治疗的有效性和靶向性。

TRPC3对上皮性卵巢癌细胞株迁移和侵袭的影响

目的:探讨瞬时受体电位通道C3(TRPC3)对人卵巢癌细胞迁移、侵袭能力的影响。方法:采用蛋白免疫印迹法和实时荧光定量PCR法分别检测卵巢癌细胞株SKOV3、ES-2和HEY-T30中TRPC3蛋白和m RNA的表达水平。通过Transwell迁移实验(不含Matrigel胶的Transwell小室)和Transwell侵袭实验分别检测卵巢癌细胞株SKOV3、ES-2和HEY-T30的迁移、侵袭能力。结果:在SKOV3、ES-2和HEY-T30三种卵巢癌细胞株中,ES-2中TRPC3的蛋白和m RNA表达均显著高于其他两株(P<0.05)。Transwell迁移实验和Transwell侵袭实验显示卵巢癌细胞株ES-2的迁移、侵袭能力均显著高于其他两种细胞株(P<0.05)。结论:瞬时受体电位通道C3(TRPC3)在ES-2人卵巢癌细胞中高表达,并可能促进人卵巢癌细胞的迁移、侵袭。

辛二酰苯胺异羟肟酸联合紫杉醇对卵巢癌紫杉醇耐药细胞存活与凋亡的影响

目的研究辛二酰苯胺异羟肟酸(suberoylanilide hydroxamic acid,SAHA)与紫杉醇(paclitaxel,PTX)单独及联合应用对人卵巢癌紫杉醇耐药细胞OC3/P存活及凋亡的影响,初步探讨两种药物联合应用是否具有协同作用。方法采用倒置显微镜观察不同药物处理对细胞形态的影响;用四甲基偶氮唑蓝(MTT)比色法测定各组细胞生长抑制情况;流式细胞仪AnnexinⅤ-FITC/PI法检测各组细胞凋亡率,并进行联合用药分析。结果不同药物处理后,倒置显微镜下可见细胞形态发生改变,联合用药组形态变化较单独用药组显著;MTT法检测细胞生长情况,结果显示,联合用药组较单独用药组具有显著抑制OC3/P细胞存活的作用(P<0.05),析因设计方差分析显示,两药物存在正交互作用,并由金式公式计算表明两药物具有协同作用。进一步利用流式细胞术检测各组细胞凋亡情况,结果表明,联合用药组诱导凋亡的比率显著高于单药组,且差异具有统计学意义(P<0.05)。结论 SAHA联合PTX可有效抑制人卵巢癌紫杉醇耐药细胞OC3/P的存活并诱导其凋亡,两药物联合有协同效应。

Screening of the Metastasis-Associated Genes by Gene Chip in High Metastatic Human Ovarian Cancer Cell Lines

Affymetrix U133A oligonucleotide microarrays were used to study the differences of gene expressions between high （H） metastatic ovarian cancer cell line, HO-8910PM, and normal ovarian tissues （C）. Bioinformatics was used to identify their chromosomal localizations. A total of 1,237 genes were found to have a difference in expression levels more than eight times. Among them 597 were upregulated [Signal Log Ratio （SLR） ≥3], and 640 genes were downregulated （SLR≤-3）. Except one gene, whose location was unknown, all these genes were randomly distributed on all the chromosomes. However, chromosome 1 contained the most differentially expressed genes （115 genes, 9.3%）, followed by chromosome 2 （94 genes, 7.6%）, chromosome 12 （88 genes, 7.1%）, chromosome 11 （76 genes, 6.1%）, chromosomes X （71 genes, 5.7%）, and chromosomes l7 （69 genes, 5.6%）. These genes were localized on short-arm of chromosome （q）, which had 805 （65.1%） genes, and the short arms of No.13, 14, 15, 21, and 22 chromosomes were the only parts of the chromosomes where the differentially expressed genes were localized. Functional classification showed that most of the genes （306 genes, 24.7%） belonged to the enzymes and their regulator groups. The subsequent group was the nucleic acid binding genes （144 genes, 11.6%）. The rest of the top two groups were signal transduction genes （137 genes, 11.1%） and proteins binding genes （116 genes, 9.4%）. These comprised 56.8% of all the differentially expressed genes. There were also 207 genes whose functions were unknown （16.7 %）. Therefore it was concluded that differentially expressed genes in high metastatic ovarian cancer cell were supposed to be randomly distributed across the genome, but the majority were found on chromosomes 1, 2, 12, 11, 17, and X. Abnormality in four groups of genes, including in enzyme and its regulator, nucleic acid binding, signal transduction and protein binding associated genes, might play important roles in ovarian cancer metastasis. Those genes need to be further studied.

Role of Tissue Factor Pathway Inhibitor-2 in Ovarian Tumor Migration and Invasion

Objective: To elucidate the relation between human tissue factor pathwayinhibitor-2 (TFPI-2) expression and ovarian tumor migration and invasion. Methods: Human TFPI-2expression vector pBos-Cite-neo/TFPI-2 was transfected into ovarian tumor cells line A2780- Afterthe transfected cells were selected by G418, transfected and nontransfected cells were screened forTFPI-2 mRNA and protein by reverse transcription-polymerase chain reaction and Western blotanalysis, respectively. The number of transfected or nontransfected cells passing through membraneof Boyden chamber was counted as the basis assessing tumor cells migratory and invasive behaviors.Results: Expression of mRNA and protein of TFPI-2 was detectable in transfected cells. In invasionassay, the number of TFPI-2-expressing cells to traverse a Matrigel-coated membrane was obviouslydecreased compared with that of nonexpressing cells (59.3±6.5 vs 109.7±5.5, P 【 0.01); While inmigration assay, no significant difference through a noncoated membrane was observed amongtransfected and nontransfected cells (114.7±8.6 vs 127.3±7.1, P 】 0.05). Conclusion: Expression ofTFPI-2 may strongly inhibit the invasive ability of ovarian tumor cells in vitro, but has no effecton the migratory ability which provides an experimental basis for genotherapy of human ovariantumor.

Apoptosis Rate and Objective Diagnosis of Drug Resistance of Ovarian Cancer Cell Lines

Objective： To investigate whether the change of drug resistance degree could be evaluated by apoptotic rate in ovarian cancer cell lines. Methods： Human epithelia ovarian cancer cell line A2780 and its platinum （DDP） resistance cell line AD4 were used. They were divided into 4 groups respectively （A2780-DDP group, A2780-DDP＋VRM group, AD4-DDP group and AD4-DDP＋VRM group）. 3-（4, 5- dimethylthiazol-2-yl）-2, 5-diphenyl-2H-tetrazolium bromide （MTT） was used to measure the multiple of drug resistance. The expression of drug-resistance genes （mdrl, TopoⅡα and GSTπ） was detected by using reverse transcription polymerase chain reaction （RT-PCR）. Semi-quantity assay was proceed by rate the of multidrug resistance genes to G3 PDH gene. Apoptosis was measured by DNA gel electrophoresis and flow cytometry respectively. The advantages and disadvantage of evaluating drug-resistance with these three methods were analyzed. Results： The 50% inhibition concentration （IC50） of A2780 and AD4 was 19.2 μg/mL and 66 μg/mL respectively, and the resistance fold of the AD4 was 3.4. Some drug-resistance genes could be detected by RT-PCR in A2780 and AD4 cell lines. The expression of mdrl was only （0.09±0.03）×10^-2 ： 1 and （0.10±0.02） × 10^-2：1 respectively （rate to G3 PDH gene） with the difference being not significant between them. The expression of TopoⅡα in the A2780 cells was （2.60±0.12）×10^-2：1 and （0.11±0.03）× 10^-2：1 in the AD4 cells respectively with the difference between them being significant. On the contrary, the expression of GSTπ in A2780 cells was lower than in AD4 cells, and the ratio was （0.11±0.03）×10^-2：1 and （3.13±0.14）×10^-2：1 respectively with tile difference being significant between them. There was no significant difference among the genes expression after the drugs were given for 6 h, 12 h and 24 h. couldn＇t reflect the change of drug-resistance timely. DNA gel electrophoresis used to detect apoptosis was only a qualitative analysis. Different drug resistance degrees may be detected by flow cytometry as early as few hours after drugs were given, which realized the earlier and quantities detection of drug resistance. Conclusion： Detection of apoptosis with flow cytometry may not be affected by the variety of drug-resistance genes, suggested this was a general, quantitative and objective method to reflect drug resistance.

Related Study on the Nm23-H1 Gene Expression in the Model of Ovarian Carcinoma Cell Lines with High Frequent Metastasis

Objective: To select the ovarian carcinoma cell lines with high frequent metastasis and study the association between nm23-H1 gene expression and metastasis of ovarian carcinoma. Methods: Each ovarian cancer cell line was transplanted subcutaneously into the flank of nude mice, and the metastatic behavior was evaluated by counting lung tumor foci at different time points. The metastatic tumors were cultured in vitro, then substrain was established and transplanted subcutaneously three times. The RNA level of nm23 in 8 human ovarian cancer cell lines were examined by northern-blot. Results: Of the 8 human ovarian cancer cell lines, 4 had high requent metastatic potentiality. The expression of nm23 RNA in human ovarian cancer cells was inversely related to metastatic behavior in the experimental animals (r=0.96, P=0.0001). Conclusion: The difference of the tendency of metastasis which was determined by genetic and molecular levels was significant among different type of cell lines and subtypes. The expression of nm23 mRNA in human ovarian carcinomas was correlated closely with the reduced metastatic behavior in experimental animals and may serve as a sensitive prognostic indicator for ovarian cancer.

Identification of differentially expressed long non-coding RNAs in human ovarian cancer cells with different metastatic potentials

Objective： To identify differentially expressed long non-coding RNAs （lncRNAs） involved in the metastasis of epithelial ovarian cancer. Methods： An in vitro invasion assay was performed to validate the invasive capability of SKOV3 and SKOV3.ip1 cell lines. Total R.NA was then extracted, and microarray analysis was performed. Moreover, nine lncRNAs were selected for validation using RT-qPCR. Results： Compared with the SKOV3 cells, the SKOV3.ip1 cells significantly improved in the in vitro invasive activity. Of the 4,956 lncRNAs detected in the microarra~ 583 and 578 lncRNAs were upregulated and downregulated, respectivel~ in SKOV3.ip1 cells, compared with the parental SKOV3 cells. Seven of the analyzed lncRNAs （MALAT1, H19, UCA1, CCAT1, LOC645249, LOC100128881, and LOC100292680） confirmed the deregulation found by microarray analysis. Conclusion： LncRNAs clusters were differentially expressed in ovarian cancer cells with varying metastatic potentials. This result indicates that some lncRNAs might exert a partial or key role in epithelial ovarian cancer metastasis. Further studies should be conducted to determine the roles of these lncRNAs in ovarian cancer metastasis.

PGC-la induces apoptosis in human epithelial ovarian cancer cells through a PPARy-dependent pathway

Peroxisome proliferator-activated receptor gamma （PPAR）,） coactivator-1 alpha （PGC-1α） coactivates multiple transcription factors and regulates several metabolic processes. The current study investigated the role of PGC-1α in the induction of apoptosis in human epithelial ovarian cancer cells. The PGC-1α mRNA level between human ovaries and human ovarian epithelial tumors was examined by quantitative RT-PCR. Less PGC- 1α expression was found in the surface epithelium of malignant tumors compared with normal ovaries. Overexpression of PGC-1α in human epithelial ovarian cancer cell line Ho-8910 induced cell apoptosis through the coordinated regulation of Bcl-2 and Bax expression. Microarray analyses confirmed that PGC-1α dramatically affected the apoptosis-related genes in Ho-8910 cells. Mitochondrial functional assay showed that the induction of apoptosis was through the terminal stage by the release of cytochrome c. Furthermore, PG-C- 1 α-induced apoptosis was partially, but not completely, blocked by PPAR）, antagonist （GW9662）, and suppression of PPAR）, expression by siRNA also inhibited PGC-1α-induced apoptosis in Ho-8910 cells. These data suggested that PGC-1α exerted its effect through a PPARγ-dependent pathway. Our findings indicated that PGC-1α was involved in the apoptotic signal transduction pathways and downregulation of PGC-1α may be a key point in promoting epithelial ovarian cancer growth and progression.

ROLE OF ERK1/2 KINASE IN CISPLATIN-INDUCED APOPTOSIS IN HUMAN OVARIAN CARCINOMA CELLS

Objective To investigate the role of extracellular regulated kinase (ERK1/2) pathway in cisplatin-induced apoptosis in human ovarian carcinoma cells. Methods Cisplatin-induced apoptosis were stained with DAPI and was assessed microscopically in human epithelial adenocarcinoma ovarian cell line SKOV3 cells. ERK activation was determined by Western blotting using an anti-phospho-ERK antibody to detect ERK activity. The effect of PD98059 on ERK activity induced by cisplatin was detected by MTT assay. Results Marked apoptosis of SKOV3 cells resulted from 48 hours treatment with 20 μg/mL cisplatin. Strong activation of ERK was led to by 15 μg/mL cisplatin. Dose response and time course of cisplatin induced apoptosis in SKOV3 cells. Cisplatin-induced ERK activation occurred at 12 hours and increased to highest induction at 24 hours by Western blotting. The effect of PD 98059 on ERK activity induced by cisplatin at the concentration of 100 μmol/L PD 98059. Statistically significant decreased in cell survival were observed with 100 μmol/L PD 98059 at 15 and 20 μg/mL cisplatin (P< 0.05). Conclusions Cisplatin activates the ERK signaling pathway in ovarian cancer cell line SKOV3. Inhibition of ERK acti-vity enhances sensitivity to cisplatin cytotoxity in ovarian cancer cell line SKOV3. Evaluation of ERK activity could be useful in predicting which ovarian cancer will response most favorably to cisplatin therapy.

Discovery of Metastasis-Associated Biomarkers in Ovarian Cancer Using SELDI-TOF: An in Vitro and Clinical Study

OBJECTIVE To identify metastasis-related biomarkers in humanovarian cancer cell lines and in serum.METHODS We isolated total protein from cell lysis solutionsand cultured supernatants from 2 human ovarian cancer cell linesand used SELDI-TOF-MS to detect the differential expressionof the proteins in the 2 cell lines.The proteomic spectra weregenerated using weak cation exchange chips.The biomarkerswere validated by analyzing serum proteins or peptides in ovariancancer patients,relapsed ovarian cancer patients,patients withbenign ovarian tumors,and healthy people.RESULTS Four proteins in the culture supernatant fromHO-8910PM cells were up-regulated,relative to the culturesupernatant of HO-8910 cells.One protein (3,144 Da m/z value)was up-regulated in both the cell lysis solution and in the culturesupernatant of HO-8910PM cells.In addition,expression of the3,144 Da m/z protein differed significantly between serum fromthe 26 ovarian cancer patients,from the 22 relapsed ovarianpatients and from the 37 healthy women (P<0.01).However,therewas no difference between patients with benign ovarian tumorsand healthy people (P>0.5).CONCLUSION Ovarian cancer cell lines with high or lowmetastatic potential have distinct protein profiles.Protein 3,144Da m/z could be a useful biomarker for diagnosing ovarian cancermetastasis.

Genistein sensitizes ovarian carcinoma cells to chemotherapy by switching the cell cycle progression in vitro

Objective:To address how genistein sensitizes the chemotherapy-resistant ovarian carcinoma cells and promotes apoptosis in the respect of cell cycle and the regulation of survivin expression in the process.Methods:Ovarian SKOV-3 carcinoma cell line was treated with genistein or cisplatin either alone or in combination.Cell viability was showed by MTT method.Cell cycle and apoptosis were detected by flow cytometry.Survivin mRNA and protein were revealed by RT-PCR and immunocytochemistry,respectively.Results:Genistein could reduce the cell viability in a dose-dependent manner,while cisplatin did so at a much higher level.In contrast,if the two agents were treated in combination,half growth inhibition(IC50) value for cisplatin was reduced remarkably and the effect was synergistic as analyzed by isobologram.In particular,the reduced cell viability was exhibited by a switch in cell cycle progression,as the cells were arrested in G2/M phase and the G0/G1 phase-fraction was significantly decreased.The reduced cell viability appeared to involve apoptosis,based on our results from flow cytometry and Hoechst 33258 staining.In the meanwhile,genistein performed the inhibitory effect on cisplatin-induced survivin expression.Conclusion:Genistein can sensitize ovarian carcinoma cells to cisplatin therapy with the inhibition of survivin expression as the potential mechanism.

Effects of HLEC on the secreted proteins of epithelial ovarian cancer cells prone to metastasize to lymph nodes

Objective： To study explores the effect of HLEC on the secreted proteins of epithelial ovarian cancer （EOC） cells （SKOV3-PM4） with directional highly lymphatic metastasis. Methods： Supernatants of four groups of cultured cells, namely, SKOV3 （A）, SKOV3＋HLEC （B）, SKOV3-PM4 （C）, SKOV3-PM4＋HLEC （D）, were collected, and their proteins were detected by antibody arrays and iTRAOcZD-LC-MALDI- TOF/TOF/MS. Significantly differential proteins were further analyzed via bioinformatics and validated in human serums and cell media via ELISA. Results： Results of antibody arrays and mass spectrometry demonstrated that GRN and VEGFA were upregulated in group C （compared with group A）, whereas IGFBP7 and SPARC were downregulated in group D （compared with group C）. Comprehensive bioinformatics analysis results showed that IGFBP7 and VEGFA were closely linked to each other. Further validation with serums showed statistical significance in VEGFA and IGFBP7 levels among groups of patients with ovarian cancers, benign tumors, and control groups. Two proteins were upegulated in the first group. VEGFA in the control group was downregulated. For IGFBP, upregulation in the control group and down-regulation in the first group were also observed. Conclusion： The HLEC microenvironment is closely associated with directional metastasis to lymph nodes and with differential proteins including cell stromal proteins and adhesion factors. The upregulation of VEGFA and GRN and the downregulation of SPARC and IGFBP7 are closely associated with directional metastasis to lymph nodes in EOC cells.

Induction of mitochondrion-mediated apoptosis of CHO cells by tripchloro lide

Tripchlorolide (TC) is a potent antitumor reagent purified from a Chinese herb Tripterygium Wilfordii Hook. f.. However, its cellular effects and mechanism of action are unknown. We showed here that TC induced apoptosis of Chinese Hamster Ovary (CHO) cells in time- and dose-dependent manners. TC resulted in the degradation of Bcl-2, the translocation of Bax from the cytosol to mitochondria, and the release of cytochrome c from mitochondria. Stable overexpression of human Bcl-2 could reduce the apoptosis of TCtreated cells by blocking the translocation of Bax and the release of cytochrome c. These results indicate that TC induces apoptosis of CHO cell by activating the mitochondrion-mediated apoptotic pathway involving the proteins of Bcl-2 family and cytochrome c.

SEVEN CASES OF EPITHELIAL OVARIAN CARCINOMA WITH BRAIN METASTASIS

Objective To summarize the clinical characteristics, treatment, and prognosis of brain metastasis in patients with epithelial ovarian carcinoma. Metbods Retrospective analysis was conducted in 7 cases of brain metastases of epithelial ovarian carcinoma from January 1986 to March 2007 in Peking Union Medical College Hospital for summarizing therapy results and prognosisaffecting factors. Results Incidence of brain metastases of epithelial ovarian carcinoma was about 0. 66% （7/1 055 ）. Serous adenocarcinoma was the predominant pathological type in 4 cases and the subsequent was adenocarcinoma in 3 cases. All the patients were diagnosed at late stage, 6 cases with the International Federation of Gynecology and Obstetrics （HGO） stage Ⅲc and 1 with FIGO stage IV. The mean duration from diagnosis of ovarian carcinoma to brain metastasis was 32.7 ± 20. 0 months （range, 23-73 months）. Single metastasis focus occurred in 43% of cases and multiple metastases in 57% of cases. Fifty-seven percent of patients presented extracranial metastasis. Serum CA125 played a role in monitoring reoccur- rence and brain metastases. The average survival time was about 12 months. Better treatment with prolonged survival could be achieved by combination of operation and chemotherapy or combination of radiotherapy with chemotherapy. Concltusions As a rare condition, brain metastasis of epithelial ovarian carcinoma is rising in incidence with improved treatment of ovarian carcinoma and prolonged survival. However, brain metastasis indicates bad prognosis which can be improved by combined therapy.

ZNF217 expression correlates with the biological behavior of human ovarian cancer cells

The aim of the study was to investigate the correlation of zinc-finger protein 217 （ZNF217） gone ex- pression with the biological behavior of human ovarian cancer HO-8910 cells. Methods： The expression of ZNF217 in ovarian carcinoma cell line：s was detected by RT-PCR and Western blot, respectively. The biological behaviors of the transfectants were investigated by MTT, in vitro Boyden chamber and in vivo invasion assay, respectively. Results： RT-PCR and Western blotting revealed that transfection of ZNF217 into the HO-8910 cells significantly increased their proliferation along with mark- edly enhanced in vitro and in vivo invasion and metastatic abilities. MTT assay showed that the proliferation ability of pEGFP- N1-ZNF217/HO-8910 cells was significantly higher than that of pEGFP-N1/HO-8910 cells and HO-8910 cells （P 〈 0.001）. The Boyden chamber assay showed that the numbers of migrating pEGFP-N1-ZNF217/HO-8910, pEGFP-N1/HO-8910 and HO-8910 cells were （141.25 ± 13.91） cells/200 x field, （82.50 ± 11.73） cells/200 × field and （81.75 ± 12.12） cells/200 x field, respectively, with a significant difference between them （F = 29.274, P 〈 0.001）. The nude mouse experiment showed that the in vivo tumor formation ability of pEGFP-N1-ZNF217/HO-8910 cells was significantly higher than that of pEGFP-N1/HO-8910 cells （P 〈 0.001）. Conclusion： Based on these clinical and laboratory observations, we conclude that ZNF217 may contribute to ovarian cancer invasion and metastasis, and associated with worse clinical outcomes. We evaluated ZNF217＇s role as a biomarker of ovarian carcinogenesis and tumor progression in patient samples and explored possible molecular mechanisms in promoting tumor growth and invasion.

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.

Mechanism of induction apoptosis of Onychin in ovarian cells in vitro

Objective： The aim of the study was to investigate the possible mechanism of induction apoptosis of Onychin （ONY） in ovarian cancer HO-8910 cells in vitro. Methods： Human ovarian cancer HO-8910 cells were cultured in vitro. Inhibi- tory effect of ONY on the viability of HO-8910 cells was evaluated by the MTT assay. Apoptosis of HO-8910 cells treated with different concentrations of ONY for 48 h was detected by FCM. Expression of proteins related to apoptosis was analyzed by Western blot. Results： ONY significantly inhibited the viability of human ovarian cancer HO-8910 cells in a dose-dependent and time-dependent manner, and the ICso was 10.48 pg/mL for 48 h. The cells treated with ONY showed typical morphological change of apoptosis and increased cells of sub-G1 population by FCM in a dose-dependent. Western blot showed that ex- pression of Bax, cytochrome C, caspase-9 and caspase-3 proteins were upregulated and protein level of Bcl-2 was depressed after treatment with ONY in a concentration dependent. Conclusion： Apoptosis of ovarian cancer HO-8910 cells was induced by ONY through mitochondrial apoptosis pathway in vitro.

The Effect of 17 β-Estradiol on Invasion by the Ovarian Clear Cell Adenocarcinoma Cell Line ES-2 and the Molecular Mechanism Involved

OBJECTIVE To assess the effect of 17 β-estradiol（E2） on cell proliferation, cell invasiveness and its regulation of MTA3, Snail and matrix metalloproteinase 2 （MMP-2） expression in the ovarian clear cell adenocarcinoma cell line ES-2, and to further investigate the mechanism involved. METHODS We first investigated expression of ERα, ERβ, PR and E-cadherin of ES-2 cells by RT-PCR and Western blots. Before all experiments, the ES-2 cells were grown in medium depleted of steroid for more than 7 days. Following treatment with 10^-7,10^-8 and 10^-9 M E2, cell viability of the ES-2 cells was determined by the MTT method, and the cell cycle distribution and apoptosis were examined by flow cytometry （FCM）. Invasion and mobility assays were performed using modified Boyden chambers. MTA3, Snail and MMP-2 mRNA expression was measured by RT-PCR, and Snail, MMP-2 protein levels were determined by IHC. MMP-2 activity was assayed by zymography. RESULTS RT-PCR and Western Blots showed that theexpression of ERα and E-cadherin mRNA and protein in the ES-2 cells was negative, while ERβ and PR expression was positive. E2 at 10^-7,10^-8 or 10^-9M stimulated cell proliferation. A level of 10^-8M E2 reduced the proportion of G0-G1 phase cells and increased the proportion of cells in the S phase, but it had no effect on apoptosis. Invasiveness and mobility of the ES-2 cells was significantly increased by 10^-8M E2. Treatment with 10^-8M E2 led to reduced MTA3 mRNA expression, and elevated Snail and MMP-2 mRNA and protein levels. CONCLUSION E2 enhanced invasion by the ES-2 cells. The effects observed maybe mediated by down-regulation of MTA3 and up-reguation of Snail and MMP-2.

γ-Secretase Inhibitor, DAPT Inhibits Self-renewal and Stemness Maintenance of Ovarian Cancer Stem-like Cells In Vitro

Objective: The Notch signaling pathway plays an important role in the stem cell signaling network and contributes to tumorigenesis. However, the functions of Notch signaling in ovarian cancer stem cells (OCSCs) are not well understood. We aimed to investigate the effects of Notch blockade on self-renewal and stemness maintenance of OCSCs. Methods: Ovarian cancer stem-like cells were enriched from ovarian cancer cell lines in serum-free medium. A γ-secretase inhibitor, (DAPT), was used to block Notch signaling. MTT assays were performed to assess self-renewal and proliferation inhibition, flow cytometry was performed to analyze cell surface marker and immunofluorescence, Western Blot and Real-time RT-PCR assays were performed to detect Oct4 and Sox2 protein and mRNA expression of the Ovarian cancer stem-like cells treated with DAPT. Results: Notch blockade markedly inhibits self-renewal and proliferation of ovarian cancer stem-like cells, significantly downregulates the expression of OCSCs-specific surface markers, and reduces protein and mRNA expression of Oct4 and Sox2 in OCSC-like cells. Conclusion: Our results suggest that Notch signaling is not only critical for the self-renewal and proliferation of OCSCs, but also for the stemness maintenance of OCSCs. The γ-secretase inhibitor is a promising treatment targeting OCSCs.