Targeted gene therapy of ovarian cancer using an ovarian-specific promoter.

OBJECTIVES: The "suicide" gene therapy of cancer using promoters such as cytomegalovirus could cause severe toxicity to normal tissues due to a lack of specificity of prodrug activation. Therefore, we investigated gene therapy of ovarian cancer using ovarian-specific promoter (OSP1) to limit the synthesis of the prodrug activating enzyme HSVtk to ovarian cancer cells. METHODS: The HSVtk expressing plasmid pOSP1-HSVtk was created and transfected into an ovarian cancer cell line OVCAR3. The ganciclovir (GCV) sensitivity of the stable transfectants was evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Tissue specificity of this promoter was evaluated by comparing the sensitivity to GCV between ovarian and nonovarian cancer cell lines after they were transfected with pOSP1-HSVtk. One transfectant sensitive to GCV was implanted intraperitoneally to immunocompromised mice which were treated subsequently with GCV. Furthermore, this ovarian cancer survival model was used to evaluate the in vivo efficacy of cationic lipid mediated pOSP1-HSVtk gene delivery followed by GCV treatment. RESULTS: Stable transfectants of OVCAR3 cells bearing OSP1-HSVtk became more sensitive to GCV treatment compared to the parental cell line and vector transfected OVCAR3 cell line. OSP1-HSVtk could specifically sensitize the OVCAR3 ovarian cancer cell line to GCV. SCID mice transplanted with the OVCAR3 transfectant and treated with GCV survived longer than the mice without GCV treatment (P = 0.032). In vivo gene delivery mediated by a cationic lipid (GL67) followed by GCV treatment yielded a longer survival in the OVCAR3 survival model (P = 0.016). CONCLUSIONS: The OSP1 promoter can selectively direct suicide gene therapy of ovarian cancer and the in vivo efficacy is improved by using a cationic lipid GL67 as delivery vehicle as opposed to the direct injection of plasmid.     

人端粒酶逆转录酶启动子调控下胞嘧啶脱氨酶-胸苷激酶融合基因治疗卵巢癌的体外研究

目的　探讨人端粒酶逆转录酶 (hTERT)启动子调控下的融合双自杀基因———胞嘧啶脱氨酶 胸苷激酶 / 5 氟胞嘧啶 更昔洛韦 (CD TK/ 5 FC GCV)系统对人卵巢癌细胞及正常细胞的体外杀伤作用。方法　应用脂质体转染法将hTERT核心启动子报告质粒pBTdel 2 79转染人卵巢癌细胞系3AO、正常卵巢上皮细胞 (NOEC)和人胚肺成纤维细胞株HELF ,用荧光素酶分析检测hTERT启动子活性 ;应用RT PCR技术检测hTERTmRNA的表达水平。应用基因克隆技术分别构建hTERT启动子和巨细胞病毒 (CMV)启动子调控下的CD TK基因真核表达载体pBTdel 2 79 CD TK和pcDNA3 CD TK ,以及hTERT启动子调控下的TK基因表达载体pBTdel 2 79 TK。用四甲基偶氮唑蓝 (MTT)法和流式细胞术检测pBTdel 2 79 CD TK/ 5 FC GCV系统和pcDNA3 CD TK/ 5 FC GCV系统对上述 3种细胞不同的杀伤作用 ;应用RT PCR技术检测pBTdel 2 79 CD TK和pcDNA3 CD TK转染前后 3AO和NOEC细胞中CD和TK基因的表达情况。用扫描电子显微镜观察pBTdel 2 79 CD TK/ 5 FC GCV作用后 3AO细胞的形态变化。结果　卵巢癌细胞系 3AO中hTERT启动子活性增高 ,为 2 4 1% ,RT PCR检测hTERTmRNA为阳性 ,而在正常细胞NOEC和HELF中 ,hTERT启动子活性仅为 0 3%和 0 7% ,hTERTmRNA为阴性。与p     

VEGF- and LPA-induced telomerase in human ovarian cancer cells is Sp1-dependent

OBJECTIVE: Both vascular endothelial growth factor (VEGF) and lysophosphatidic acid (LPA) are secreted by ovarian cancer cells and are known to promote cancer cell growth though the exact mechanism(s) are not completely understood. Since telomerase, a ribonucleprotein expressed in 95% of ovarian cancers, plays an important role in cellular immortalization, growth, and tumor progression, we examined whether telomerase is a molecular target of LPA and VEGF in ovarian cancer. METHODS: Telomerase-positive ovarian carcinoma cell lines PA-1, SW 626, and one telomerase-negative, non-tumorigenic SV40 large-T antigen-transfected human ovarian surface epithelial (IOSE) cell line, FHIOSE 118, derived from normal ovarian surface epithelium were cultured with and without VEGF and LPA for 4 h and 24 h, respectively. Telomerase PCR-ELISA, RT-PCR, VEGF ELISA and luciferase assays were performed to determine the effect of VEGF and LPA on telomerase activity in ovarian cancer cells. Western blot analyses were used to examine the signaling pathway involved in telomerase regulation by VEGF and LPA. RESULTS: We report that: (1) both VEGF and LPA upregulate telomerase activity; (2) LPA induction of telomerase activity is VEGF-dependent; (3) VEGF and LPA induction of telomerase activity is ERK 1/2-dependent; and (4) Sp1 binding sites within the proximal 976- to 378-bp regions of the hTERT promoter are essential for VEGF- and LPA-induced hTERT promoter activity. CONCLUSION: Consequently, these data show the novel finding that VEGF can regulate telomerase activity in non-endothelial cells and that telomerase appears to be a novel molecular target of LPA.     

宫颈癌细胞系中hTERT启动子水平及其与端粒酶活性相关性的研究

目的:探讨宫颈癌细胞系中人端粒酶逆转录酶(hTERT)启动子的活性及其与hTERT mRNA表达和端粒酶活性之间的关系。方法:应用脂质体转染法将hTERT核心启动子基因转入宫颈癌细胞系Hela和正常人皮肤表皮细胞中,并用荧光素酶检测实验检测其中hTERT启动子的活性;应用RT-PCR半定量法检测2种细胞中的hTERT mRNA表达水平:应用PCR-ELISA定量检测这2种细胞中的端粒酶活性。同时以端粒酶阳性的永生化人胚肾成纤维细胞系HEK293的检测结果作为阳性对照,以端粒酶阴性的人胚肺成纤维细胞系HELF的检测结果作为阴性对照。结果:宫颈癌细胞系HeLa和正常人皮肤表皮细胞中的hTERT启动子活性(视每种细胞中pGL3一control的启动子活性为100％)分别为20.1％和0.3％;hTERT mRNA相对表达水平分别为0.63和0(视HEK293表达水平为1):端粒酶活性分别为0.393和0.144(视>0.2为阳性)。结论:宫颈癌细胞系中hTERT启动子活性、hTERT mRNA表达水平和端粒酶活性均特异性增高,而正常皮肤表皮细胞中则受抑制或不表达。hTERT启动子活性水平与hTERT mRNA表达水平及端粒酶活性之间有显著相关性。     

The telomerase activity and expression of hTERT gene can serve as indicators in the anti-cancer treatment of human ovarian cancer

OBJECTIVE: The aim of this study was to evaluate the clinicopathological significance of telomerase activity and expression of hTERT gene in human ovarian cancer. The potential value of them as indicators for chemotherapy in ovarian cancer cells was also studied. MATERIALS AND METHODS: A total of 73 samples and ovarian cancer cell lines HO-8910 and COC1 were studied. Telomerase activity was detected by PCR-TRAP-ELISA assay and the expression of the hTERT mRNA was analyzed by semi-quantitative RT-PCR. Alteration of the telomerase activity and hTERT mRNA were also analyzed in the ovarian cancer cells treated with different concentration and different time of cisplatin. Cytogenetic analysis was performed to compare the telomere status in the OH-8910 cells pre- and post-cisplatin treatment. The associations between these two markers and cisplatin induced-apoptosis were respectively analyzed in COC1 cells by the flow cytometry. RESULTS: Telomerase activity are highly increased in malignancy (0.795+/-0.168(A450-655 nm)) than borderline (0.389+/-0.174(A450-655 nm)), benign tumors (0.236+/-0.102(A450-655 nm)) and normal ovary (0.213+/-0.070(A450-655 nm)) (p < 0.05). Twenty samples showed detectable levels of hTERT. The hTERT gene positive lesion showed significantly higher telomerase activity than negative (p = 0.004). There is a significant correlation between the telomerase activity and expression of hTERT (r = 0.921). Both telomerase activity and expression of hTERT can reflect the chemotherapeutic effect of cisplatin in a time-dependent and dose-dependent manner. Treatment with 10 microM cisplatin, the hTERT mRNA decreased after 12h and completely disappeared after 48 h, whereas the telomerase activity did not decrease until 24h. Results from cytogenetic analysis and flow cytometry assay confirmed that the alterations of these two markers are associated with the anti-cancer treatment of cisplatin. CONCLUSION: Expression of hTERT gene is rate-limiting with the activation of telomerase. Both of they may be useful in the predicting of chemotherapeutic effect in ovarian cancer.     

Autologous antibodies eluted from membrane fragments isolated from the effusions of human ovarian epithelial neoplasms. I. Quantitation of antibodies

Cyst and ascites fluids from patients with ovarian epithelial neoplasms contain large amounts of soluble immunoglobulins without detectable antibody activity against human ovarian tumor cell lines by indirect immunofluorescence. Membrane fragments were prepared from 56 human ovarian effusions, and the presence of membrane-bound IgG, IgA, and IgM was demonstrated. The predominant membrane-bound immunoglobulin class was IgG, which ranged from 18 to 4275 ng/ml on samples tested, whereas IgA was present in the range of 5 to 52 ng/ml. The autologous membrane-bound antibodies strongly recognized cell-surface antigens on four human ovarian cell lines and four surgical specimens of human ovarian adenocarcinoma but did not react with normal human ovaries, non-ovarian normal and neoplastic tissues, or non-ovarian human cell lines by indirect immunofluorescence assay. These studies indicate that patients with ovarian cancer have the capability of recognizing and forming antibodies against autologous ovarian tumor-associated antigens.     

Telomeric instability and reduced proliferative potential in ovarian surface epithelial cells from women with a family history of ovarian cancer.

OBJECTIVE: Increased telomeric instability in normal ovarian surface epithelium may contribute to ovarian carcinogenesis in women from families with a high frequency of breast/ovarian cancer. To test this hypothesis, we compared proliferative potential, mean telomeric length, and telomerase activity in SV-40 large T-antigen transfected cell lines derived from normal ovarian surface epithelium of women with and without a familial history of breast/ovarian cancer. METHODS: Telomeric instability was examined in SV-40 large T-antigen transfected cell lines of normal ovarian surface epithelium from patients with (FHIOSE, N = 5) and without (NFHIOSE, N = 11) a history of familial breast/ovarian cancer. The duration and total attainable number of population doublings, mean telomeric length, rate of telomeric loss, and telomerase activity were determined by cell counts, Southern blot analysis, and PCR ELISA. RESULTS: FHIOSE cells attained fewer population doublings than NFHIOSE cells and doubled at approximately half the rate of NFHIOSE cells, indicating a reduced proliferative capacity in FHIOSE cells. While telomerase activity was not detected in FHIOSE or NFHIOSE cell lines, mean telomeric lengths in FHIOSE were generally 1 kb shorter than in NFHIOSE cells and the rate of telomeric loss as a function of population doublings was up to threefold greater in FHIOSE cells. CONCLUSIONS: Increased telomeric instability and reduced growth potential suggest greater proximity to replicative senescence in ovarian surface epithelium from women with a familial history of breast/ovarian cancer. Consequently, an accumulation of genetic aberrations due to accelerated cellular aging may contribute to the enhanced susceptibility for malignant transformation and earlier onset in heritable ovarian cancer.     

卡铂诱导卵巢癌细胞凋亡与端粒酶活性、hTERT基因表达改变的关系

目的研究卡铂诱导的卵巢癌细胞凋亡与端粒酶活性、hTERT基因表达改变的关系。探讨检测端粒酶活性和hTERT基因表达作为铂类药物治疗卵巢癌细胞的监测指标的潜在应用价值。方法在卵巢癌细胞HO-8910、COC1中采用PCR—ELISA方法检测端粒酶活性、RT—PCR半定量方法检测hTERT基因mRNA的表达。采用流式细胞仪分析Annex—V—Fluos染色的肿瘤细胞细胞凋亡情况。结果不同浓度卡铂1μM，10μM和100μM诱导卵巢癌细胞凋亡后，卵巢癌细胞HO-8910、COC1中的端粒酶活性和hTERT基因的表达浓度呈现出剂量依赖性和时间依赖性的下降。端粒酶活性和hTERT基因的表达的下降与卡铂诱导的卵巢癌细胞凋亡增加呈负相关（R=0．613，P=0．0347）。而且hTERT基因表达的改变比端粒酶活性更为敏感。结论检测端粒酶活性和hTERT基因的表达程度有助于判定卡铂诱导的卵巢癌凋亡的敏感性。     

端粒酶反义hTERT基因治疗对卵巢癌细胞生长抑制作用及其对顺铂疗效的影响

目的 :探讨端粒酶反义hTERT对卵巢癌细胞生长抑制作用及对顺铂疗效的影响。方法 :以TRAP PCR ELISA法检测卵巢癌SKOV3、ES 2细胞中端粒酶活性 ;以MTT法及流式细胞术测定反义hTERT对卵巢癌细胞生长的抑制作用、细胞周期阻滞及细胞凋亡的诱导作用及对CDDP疗效的影响。结果 :SKOV3及ES 2细胞中端粒酶活性分别为 2 .17U、2 .2 7U。反义hTERT能降低卵巢癌细胞端粒酶活性 ,以剂量依赖性方式抑制癌细胞生长 ;反义hTERT10 μmol L作用 2 4、72h后G1期细胞所占比例分别为 33 16%、5 3 4 7% ,细胞凋亡发生率分别为 11 66%、13 93% ;而联合应用顺铂时 ,G1期细胞比例分别为 4 2 17%、38 98% ,细胞凋亡发生率分别为 18 66%、2 7 61%。当反义hTERT取 10、2 0、4 0 μmol L时 ,卵巢癌SK OV3、ES 2细胞对顺铂的敏感性分别增加 10 4～ 2 5 5倍、11 7～ 2 0 2倍。结论 :端粒酶反义hTERT基因治疗能通过抑制端粒酶活性、增强细胞周期阻滞及诱导细胞凋亡等途径抑制卵巢癌细胞生长 ,与CDDP合用能增强对癌细胞的杀伤作用。     

卵巢上皮性癌组织中p16INK4A基因表达缺陷的意义及其与甲基化的关系

目的研究抑癌基因p16INK4A在卵巢上皮性癌(卵巢癌)组织及细胞系中的表达变化,分析其表达变化与甲基化的关系。方法选取7种卵巢癌细胞系、18份卵巢癌组织和10份正常卵巢组织为研究对象。采用甲基化特异性PCR方法检测p16INK4A基因甲基化状态;RT-PCR技术检测p16INK4A基因的mRNA表达;蛋白印迹(western blot)法检测P16INK4A蛋白的表达。5-杂氮-2′-脱氧胞苷对p16INK4A基因甲基化的卵巢癌细胞进行去甲基化处理,再次进行p16INK4A基因的mRNA和蛋白表达的检测,以及p16INK4A基因甲基化的分析。检测5-杂氮-2′-脱氧胞苷处理前后卵巢癌细胞的生长情况;并将处理前后的细胞接种于裸鼠,观测肿瘤的体积、重量。结果3种卵巢癌细胞系(Anglne、SW626和OVCAR3细胞)、6份卵巢癌组织中存在p16INK4A基因甲基化,卵巢癌细胞和卵巢癌组织中的甲基化率分别为3/7和33%(6/18)。卵巢癌细胞系、卵巢癌组织和正常卵巢组织中,p16INK4A基因的mRNA相对含量的平均值分别为0·34±0·11、0·81±0·13、1·52±0·12,蛋白相对含量的平均值分别为0·56±0·14、1·32±0·12、2·09±0·11,卵巢癌细胞系、卵巢癌组织分别与正常卵巢组织相比,差异均有统计学意义(P<0·05)。有甲基化表现的卵巢癌细胞和组织中p16INK4A基因的mRNA和蛋白表达均下降。5-杂氮-2′-脱氧胞苷处理能使p16INK4A基因甲基化的卵巢癌细胞中的p16INK4A基因的mRNA和蛋白重新表达或表达增高。与去甲基化处理前比较,去甲基化处理后Anglne、SW626和OVCAR3细胞的生长速度均减慢;接种去甲基化处理的OVCAR3细胞的裸鼠中,肿瘤体积和重量明显减小,分别为(0·243±0·022)cm3、(0·035±0·004)g。结论p16INK4A基因的表达下降或缺失在卵巢癌的发生中起重要作用,DNA甲基化是其表达缺陷的原因,去甲基化处理可以恢复p16INK4A基因的表达并抑制卵巢癌细胞的增殖。     

Anticancer effects of (-)-epigallocatechin-3-gallate on ovarian carcinoma cell lines

Purpose: A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), has been known to possess anti-cancer properties. In this study, we investigated the time-course anticancer effects of EGCG on human ovarian cancer cells to provide insights into the molecular-level understanding of growth suppression mechanism involved in EGCG-mediated apoptosis and cell cycle arrest. Methods: Three human ovarian cancer cell lines (p53 negative, SKOV-3 cells; mutant type p53, OVCAR-3 cells; and wild type p53, PA-1 cells) were used. The effect of EGCG treatment was studied via cell count assay, cell cycle analysis, FACS, Western blot, and macroarray assay. Results: EGCG exerts a significant role in suppressing ovarian cancer cell growth. Also, EGCG showed growth inhibitory effects in each cell line in a dose-dependent fashion and induced apoptosis and cell cycle arrest. The cell cycle was arrested at the G(1) phase by EGCG in SKOV-3 and OVCAR-3 cells. In contrast, the cell cycle was arrested in the G(1)/S phase arrest in PA-1 cells. EGCG differentially regulated the expression of genes and proteins (Bax, p21, Retinoblastoma, cyclin D1, CDK4, Bcl-X(L)) more than 2-fold, showing a possible gene regulatory role of EGCG. The continual expression in p21WAF1 suggests that EGCG acts in the same way with p53 proteins to facilitate apoptosis after EGCG treatment. And Bax, PCNA, and Bcl-X are important in EGCG-mediated apoptosis. In contrast, CDK4 and Rb are not important in ovarian cancer cell growth inhibition. Conclusion: EGCG can inhibit ovarian cancer cell growth through induction of apoptosis and cell cycle arrest as well as regulation of cell cycle-related proteins. Thereby, the EGCG-mediated apoptosis can be applied to an advanced strategy in the development of a potential drug against ovarian cancer.     

Internalization of cytotoxic analog AN-152 of luteinizing hormone-releasing hormone induces apoptosis in human endometrial and ovarian cancer cell lines independent of multidrug resistance-1 (MDR-1) system

OBJECTIVE: Eighty percent of human ovarian and endometrial cancers express receptors for luteinizing hormone-releasing hormone (LHRH-R). These receptors can be used for targeted chemotherapy with agents such as AN-152, in which doxorubicin is linked to analog [D-Lys(6)]-LHRH. Direct receptor-mediated antiproliferative effects of AN-152 have been shown in vitro and in vivo. In LHRH-R positive cell lines, AN-152 was more effective than doxorubicin at equimolar concentrations. This study was designed to investigate the mechanism of action of AN-512 in ovarian and endometrial cancer cells in vitro.Study design Three ovarian (SKOV-3, NIH:OVCAR-3, EFO-21) and 2 endometrial carcinoma cell lines (Ishikawa, HEC-1A) were evaluated for doxorubicin- or AN-152-induced apoptosis. Internalization and cytoplasmic release of AN-152 was monitored by confocal laser scanning microscopy and inhibited by chloroquine. Cleavage of doxorubicin from AN-152 was inhibited by carboxylesterase inhibitor, diisopropyl fluorophosphate (DFP). The surface expression of multidrug resistance-1 (MDR-1) gene product P-glycoprotein (Pgp) was measured by flow cytometry. RESULTS: Induction of apoptosis by AN-152 in LHRH-R positive Ishikawa, HEC-1A, EFO-21, and NIH:OVCAR-3 cells was significantly higher than that induced by doxorubicin, whereas the percentage of apoptotic cells in LHRH-R negative SKOV-3 was higher after treatment with doxorubicin. In EFO-21 cells, apoptosis induced by AN-152 was inhibited by pretreatment with chloroquine. Pretreatment with DFP increased AN-152-induced apoptosis in LHRH-R positive cells and reduced apoptosis in LHRH-R negative SKOV-3. Both AN-152 and doxorubicin induced surface expression of MDR-1 gene product Pgp, but the effect of AN-152 was smaller than that of doxorubicin. Pgp surface expression induced by AN-152 was inhibited by pretreatment with DFP. CONCLUSION: AN-152 is internalized through the LHRH-R and induces apoptosis in LHRH-R-positive human ovarian and endometrial cancer cell lines without activating the MDR-1 efflux pump system. The efficacy and specificity of AN-152 is inversely correlated with carboxylesterase activity.     

Oestrogen receptor α mediates 17β-estradiol enhancement of ovarian cancer cell motility through up-regulation of survivin expression

Objective

To determine the role of oestrogen receptor ?? (ER??) in the regulation of survivin expression by 17??-estradiol (E₂) in ovarian cancer cells and to evaluate the mechanism of E₂ action on ovarian cancer cell migration.

Methods

We performed RT-PCR and Western blot analysis to assess the expression of ER?? in the ovarian cancer cell lines NIH:OVCAR-3 and SKOV-3. Full-length ER?? cDNA was reintroduced into SKOV-3 cells through stable transfection. After treatment with E₂, with or without pre-incubation of anti-oestrogen compound ICI 182780, RT-PCR and Western blot analysis were performed to detect survivin expression at the mRNA and protein levels. RNA interference (RNAi) was used to inhibit the expression of survivin in SKOV-3 cells. Wound healing-induced migration and Matrigel invasion experiments were performed to determine the motility of ovarian cancer cells. RT-PCR and gelatin zymography were used to detect the expression and activity of MMP-9 in SKOV-3 cells.

Results

A stably transfected clone with over-expression of ER??, SKOV-??, was isolated. Exogenous or endogenous expression of ER?? in SKOV-3 or NIH:OVCAR-3 cells resulted in a significant up-regulation of survivin in the presence of E₂. Pre-treatment with ICI 182780 attenuated the up-regulation of survivin by E₂. Previous data from our laboratory showed that E₂ enhanced the motility of ovarian cancer cells. RNAi strongly inhibited survivin expression in SKOV-3 cells. Knock-down of survivin expression reduced the migration and invasion of SKOV-3 cells, which correlated with down-regulation of MMP9 mRNA expression and activity.

Conclusions

ER?? may be responsible for the up-regulation of survivin after E₂ treatment in ovarian cancer cells. The mechanism of oestrogen-promoted ovarian cancer metastasis may due to the up-regulation of survivin conducted through the ER?? signalling pathway.