Synergistic interaction between an anti-p185HER-2 pseudomonas exotoxin fusion protein [scFv(FRP5)-ETA] and ionizing radiation for inhibiting growth of ovarian cancer cells that overexpress HER-2

OBJECTIVES: The HER-2 proto-oncogene is overexpressed in 15-30% of ovarian cancers, providing a target for therapy in a fraction of patients. We previously described the ability of a recombinant single-chain anti-p185HER-2-Pseudomonas exotoxin A fusion protein, scFv(FRP5)-ETA, to inhibit growth of cancer cells in culture and tumor xenografts in vivo. We have also described synergistic interaction between an anti-p185HER-2-ricin A chain immunotoxin and ionizing radiation for inhibiting growth of ovarian and breast cancer cells that overexpress HER-2. Our objective in this report was to evaluate the in vitro and in vivo effects of scFv(FRP5)-ETA against SKOv3 ovarian cancer cells that have been transfected to express >10(6) p185HER-2 receptors per cell (clone-9002-18). METHODS: Inhibition of clonogenic growth was measured in vitro by limiting dilution analysis. Inhibition of tumor growth was measured in vivo using heterografts established with the same ovarian cancer cell lines. RESULTS: Clone-9002-18 cells were substantially more sensitive than parental SKOv3 cells to the cytotoxic effects of scFv(FRP5)-ETA. Exotoxin fusion protein induced apoptosis in clone-9002-18 cells, but did not affect parental SKOv3 cells. Treatment of clone-9002-18 cells with 200- to 2000-cGy external beam irradiation in combination with scFv(FRP5)-ETA produced synergistic elimination of clonogenic tumor cells in culture. In vivo, subcutaneous or intraperitoneal growth of tumor xenografts in nu/nu mice was significantly inhibited (P = 0.004) by treatment for 10 days with scFv(FRP5)-ETA or with 131I-labeled-520C9 anti-p185HER-2 radionuclide conjugate, but additive effects were not observed with combined treatment. CONCLUSION: ScFv(FRP5)-ETA deserves further evaluation for intraperitoneal therapy of ovarian cancers that overexpress p185HER-2.     

Regulation of growth of normal ovarian epithelial cells and ovarian cancer cell lines by transforming growth factor-beta.

OBJECTIVE: The purpose of this study was to study the role of transforming growth factor-beta in regulation of proliferation of normal and malignant ovarian epithelial cells. STUDY DESIGN: We examined production of and responsiveness to transforming growth factor-beta in primary monolayer cultures of epithelial cells from five normal human ovaries and in five ovarian cancer cell lines. RESULTS: In normal ovarian epithelial cells, proliferation always was inhibited by transforming growth factor-beta (greater than 40%) (p less than 0.01). Among the cancer cell lines, proliferation of one was markedly inhibited (greater than 95%) (p less than 0.01), two were only modestly inhibited (15% to 20%) (p less than 0.05), and two were unaffected. In addition, we found that all of the normal ovarian epithelial cells and four of five ovarian cancer cell lines produce transforming growth factor-beta ribonucleic acid and protein. CONCLUSIONS: These data suggest that transforming growth factor-beta may act as an autocrine growth inhibitory factor for normal ovarian epithelium in vivo. Because most of the ovarian cancer cell lines are relatively resistant to the growth inhibitory effect of transforming growth factor-beta and because one cell line does not produce transforming growth factor-beta, it is possible that loss of the transforming growth factor-beta pathway may play a role in the development of some ovarian cancers.     

M344 is a novel synthesized histone deacetylase inhibitor that induces growth inhibition, cell cycle arrest, and apoptosis in human endometrial cancer and ovarian cancer cells

OBJECTIVE: Histone deacetylase inhibitors (HDACIs) can inhibit cell proliferation, induce cell cycle arrest, and stimulate apoptosis of cancer cells. METHODS: We investigated the effects of a novel synthesized HDACI, M344, on Ishikawa endometrial cancer cell line, SK-OV-3 ovarian cancer cell line, and normal human endometrial epithelial cells. Endometrial and ovarian cancer cells were treated with various concentrations of M344, and its effect on cell growth, cell cycle, apoptosis, and related measurements was investigated. RESULTS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays showed that all endometrial and ovarian cancer cell lines were sensitive to the growth inhibitory effect of M344, although normal endometrial epithelial cells were viable after the treatment with the same doses of M344 that induced growth inhibition of endometrial and ovarian cancer cells. Cell cycle analysis indicated that their exposure to M344 decreased the proportion of cells in the S-phase and increased the proportion in the G0/G1 phases of the cell cycle. Induction of apoptosis was confirmed by annexin V staining of externalized phosphatidylserine and loss of the transmembrane potential of mitochondria. This induction occurred in concert with altered expression of genes related to cell growth, malignant phenotype, and apoptosis. Furthermore, M344 treatment of these cell lines increased acetylation of H3 and H4 histone tails. CONCLUSIONS: These results raise the possibility that M344 may prove particularly effective in the treatment of endometrial cancers and ovarian cancers.     

The influences of interleukin-1 beta converting enzyme expression on the biologic characteristics of ovarian cancer cells

OBJECTIVE: To investigate the effects of interleukin-1 beta converting enzyme (ICE) gene on the biologic characteristics of ovarian cancer cells. METHODS: A 1.3 Kilobase human ICE cDNA with 5' and 3' untranslated sequences was cloned into the EcoR I site of pLXSN retrovirus vector in sense orientation. After that, the recombinant plasmid pLXSN-ICE was transferred to virus-packing cell PA317 by electroporation method. And then the retrovirus containing human ICE cDNA generated by these PA317 cells were used to transfect human ovarian cancer cell lines, AO and 3AO. RESULTS: After being transfected with these retrovirus, the number of the clones obtained after G418 resistance selection is far less than that of controlled groups with plasmid pLXSN. The growth rate of these transfected cells was significantly suppressed in comparison with the parental cell line. Apoptosis was also found in these cells. After the transfection cancer cells were inoculated subcutaneously in nude mice, the tumor growth was significantly inhibited. CONCLUSION: It suggest that human ICE gene can suppress the phenotype and tumorigenicity in nude mice of ovarian cancer cell lines AO and 3AO.     

Granulocyte colony-stimulating factor on the growth of human ovarian carcinoma cells in vitro

Granulocyte colony-stimulating factor (GCSF) is a member of a family of glycoprotein hormones that stimulates the proliferation and differentiation of hematopoietic cells in vivo and in vitro. In ovarian cancer chemotherapy, GCSF is used clinically to build up bone marrow function after severe cytotoxicity to granulocytes by chemotherapy. Little is known about the effects of these cytokines on the growth of cancer cells. To study the influence of GCSF on the proliferation of ovarian cancer cells in vitro, five established ovarian cancer cell lines (OC-89-VGH, OC-117-VGH, OCPC-2-VGH, NIH-OVCAR-3, and NIH-SK-OV-3) were treated with the concentration ranging from 0.1 pg to 10 ng GCSF for 5 days and compared with vehicle control. In addition, we also examined the effect of GCSF (0. 01-1.0 ng) on eight primary cultures of fresh ovarian cancer tissues. Cell viability after treatment was measured by Cell Titer AQueous assay and expressed as a percentage of untreated control cultures. A decrease in cell growth (75-85%) was observed in OC-89-VGH, OC-117-VGH and OCPC-2-VGH cell lines while NIH-OVCAR-3 and NIH-SK-OV-3 cells showed minimal growth stimulation. However, all dose-response curves were nonsignificant, suggesting indirect effects. In the eight fresh tumor primary cultures treated with GCSF, no statistical significant difference in growth was observed. In conclusion, our data suggest that GCSF has little or no growth-modulatory effect on human ovarian carcinoma in vitro. Therefore, the clinical use of GCSF is unlikely to have a direct effect on tumor growth. Copyright Copyright 1999 S. Karger AG, Basel     

Overexpression of estrogen receptor-alpha in the endometrial carcinoma cell line Ishikawa: inhibition of growth and angiogenic factors

BACKGROUND: A high level of estrogen receptor-alpha (ER-alpha) is believed to be favorable in the prognosis and treatment of endometrial, ovarian, and breast cancer. High levels of ER-alpha have been shown to inhibit the growth and invasive, metastatic potential of breast cancer cell lines. To bring about these inhibitory effects, ER-alpha probably acts through other cellular factors involved in the regulation of cell growth. OBJECTIVE: To investigate the role of high levels ER-alpha in growth inhibition of endometrial cancer cells. METHODS: A human ER-alpha cDNA was stably overexpressed in an endometrial cancer cell line, namely, Ishikawa. ER-alpha-overexpressing, parent, and control Ishikawa cells were grown in vitro and their growth rates were compared by cell count. ER-alpha-overexpressing and parent Ishikawa cells were also grown in vitro as tumors in a chicken chorioallantoic membrane (CAM) model, and tumor growth and angiogenesis was measured. Finally, levels of angiogenesis-modulating factors, nitric oxide synthase (NOS), and vascular endothelial growth factor (VEGF) were examined in relation to ER overexpression. RESULTS: The growth of Ishikawa cells was found inhibited in culture as well as in the CAM model. Angiogenesis of CAM tumors was also found inhibited in ER-overexpressing cells. Angiogenic factor VEGF was inhibited whereas the activity of NOS was found elevated following ER overexpression. CONCLUSION: Our work on the Ishikawa cell line indicates that high levels of ER-alpha in endometrial cancer may inhibit cancer growth by modulating angiogenic factors, thereby limiting the blood supply to the growing tumor. Our results support the earlier data from other groups that have shown a positive correlation between high ER content and better prognosis of endometrial cancers.     

Differential induction of apoptosis by tumor necrosis factor-related apoptosis-inducing ligand in human ovarian carcinoma cells

OBJECTIVES: In this study, we examine the sensitivity of a panel of ovarian carcinoma cells, which includes four primary ovarian cancer cell samples, and four normal ovarian epithelium samples to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We also examine the intracellular regulation of TRAIL-mediated apoptosis. METHODS: The sensitivity to TRAIL was determined by short-term survival assays on seven ovarian carcinoma cell lines, four primary samples of ovarian cancer, and four normal ovarian epithelium samples. We assessed the activation of the apoptotic pathway in TRAIL-resistant and -sensitive tumor cells. The expression of TRAIL receptors was determined by flow cytometry. The protein expression of FADD, XIAP, caspase-8, caspase-3, BAX, and c-FLIP were determined by immunoblot analyses. RESULTS: We show that ovarian cancer cells display variable sensitivity to TRAIL-induced apoptosis although most cell lines have similar sensitivity to cisplatin. Normal ovarian epithelium samples were mostly sensitive to TRAIL. In sensitive cells, TRAIL induced caspase-8-dependent apoptosis, which subsequently led to activation of caspase-3. Both sensitive and resistant cells expressed caspase-8, caspase-3, FADD, XIAP, and c-FLIP at similar levels. A significant enhancement in cell death was observed in TRAIL-resistant cells when c-FLIP(L) levels were downregulated by RNA interference. CONCLUSIONS: These data suggest that sensitivity to TRAIL and chemotherapy does not necessarily correlate in human ovarian cancer cells. Cancerous cells isolated from patients with ovarian cancer show variable sensitivity to TRAIL but most normal ovarian epithelial cells are sensitive. In human ovarian cancer cells, c-FLIP(L) may participate to the regulation of the TRAIL signaling cascade.     

Gonadotropins, estradiol, and growth factors regulate epithelial ovarian cancer cell growth.

Indirect evidence suggests that gonadal steroids and gonadotropins may have a role in the genesis of epithelial ovarian cancer. In the studies reported herein, we established 17 beta-estradiol (E2) secreting cell cultures from an omental metastasis of an epithelial ovarian cancer. We demonstrate that human chorionic gonadotropin (hCG), human follicle-stimulating hormone, and epidermal growth factor (EGF) increased cell growth in a dose- and time-dependent manner, whereas E2 inhibited cell growth in the nanomolar range. Epidermal growth factor was able to partially block the negative effect of E2; a similar but quantitatively lesser effect was observed with hCG. These results provide direct evidence to support the view that gonadotropins, EGF, TGF beta (transforming growth factor), and estradiol may modulate growth of metastatic epithelial ovarian cancer cells.     

Ras antagonist inhibits growth and chemosensitizes human epithelial ovarian cancer cells

Abstract.   Beiner ME, Niv H, Haklai R, Elad-Sfadia G, Kloog Y, Ben-Baruch G. Ras antagonist inhibits growth and chemosensitizes human epithelial ovarian cancer cells. Int J Gynecol Cancer 2006; 16(Suppl. 1): 200–206.
The objective of this article was to determine whether human ovarian carcinoma cells (OVCAR-3) express significant amounts of Ras oncogene and active Ras–guanosine triphosphate (GTP) and, if so, whether the Ras inhibitor farnesyl thiosalicylic acid (FTS) inhibits their growth and chemosensitizes them to cisplatin. We assayed Ras and Ras-GTP in OVCAR-3 cells before and after FTS treatment. The effect of FTS on OVCAR-3 cell growth was assessed in terms of cell number. Because the OVCAR-3 cell line was derived from a patient who was refractory to cisplatin, we examined whether FTS enables cisplatin to induce death of these cells. Significant amounts of Ras and active Ras-GTP were expressed by OVCAR-3 cells and were reduced by 40% by FTS. FTS inhibited OVCAR-3 cell growth in a dose-dependent manner. When combined with cisplatin, FTS reduced the number of OVCAR-3 cells by 80%, demonstrating synergism between FTS and cisplatin. FTS, at a concentration range that allows downregulation of Ras and Ras-GTP in OVCAR-3 cells, also chemosensitizes these cells and inhibits their growth. These results suggest that ovarian carcinomas might respond well to Ras inhibition, both alone and when combined with cisplatin. The combined treatment would allow the use of smaller doses of chemotherapy, resulting in decreased cytotoxicity.     

Iron chelators deferoxamine and diethylenetriamine pentaacetic acid induce apoptosis in ovarian carcinoma

OBJECTIVES: Ovarian cancer remains a leading cause of death in women and development of new therapies is essential. Deprivation of iron (Fe), an essential micro-nutrient, by chelation is known to inhibit proliferation of several human cancers but its potential in ovarian cancer treatment remains unknown. We have evaluated the anti-proliferative activities of iron chelators, deferoxamine (DFO), and diethylenetriamine pentaacetic acid (DTPA), in human and rat ovarian cancer cells. METHODS: The effect of DFO and DTPA on CaOV-3 (human) and NUTU-19 (rat) ovarian cancer cells was determined by cell proliferation and apoptosis assays (Hoechst staining, DNA fragmentation, and caspase activation), cell cycle analysis, and Fe supplementation studies. RESULTS: DFO and DTPA were cytotoxic to ovarian cancer cells in a dose- and time-dependent manner. DFO inhibited proliferation of NUTU-19 and CaOV-3 cells (IC(50) at 45 and 280 microM, respectively), while DTPA inhibited proliferation of only NUTU-19 cells (IC(50) at 50 microM), at 48 h. DNA synthesis was inhibited in CaOV-3 cells by DFO (>90% at 200 microM) and in NUTU-19 by both DFO and DTPA (>90% at 50 microM). Fe supplementation effectively reversed the cytotoxic effects of DFO and DTPA. Cell cycle analysis showed a G0/G1- and S-phase block with increased apoptosis. DNA fragmentation analysis confirmed apoptosis. Increase in caspase-3, -8, and -9 activities ( approximately 2.4-fold) was associated with apoptosis. CONCLUSIONS: Our studies show that Fe chelators suppress ovarian cancer growth by inhibiting proliferation and inducing apoptosis. Therefore, Fe chelators can be potentially developed as novel therapeutic agents to treat ovarian cancer.     

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.     

Flt-3 ligand inhibits growth of human ovarian tumors engrafted in severe combined immunodeficient mice

OBJECTIVE: The current study evaluated the effects of Flt-3 ligand (FL) on the growth of human malignant ovarian tumors engrafted in severe combined immunodeficient (SCID) mice with particular attention directed at FL's effect on the host natural killer (NK) cell response against ovarian cancer xenografts. METHODS: Equal portions of surgical specimen-derived human ovarian carcinomas were engrafted subcutaneously (SC) into SCID mice. Mice were placed into one of two treatment groups 7 days after the day of implantation. Group 1 received placebo injections SC from Day 1 to Day 20 and group 2 received FL at 10 microg/day SC from Day 1 to Day 20. NK cell depletion was performed on three additional mice from group 2 starting on Day 0 using anti-asialo GM1. Serial tumor volumes were measured. On Day 21, mice from each group were sacrificed, and tumors and spleens were evaluated. Data analysis included chi(2) tests, Student t tests, and analyses of variance when appropriate. RESULTS: FL resulted in tumor growth delay compared with control (P = 0.036). When NK cell activity was depleted prior to FL administration, no tumor growth delay was observed. Spleens from FL-treated mice were larger (P < 0.01) with expanded white pulp compared with controls. Histologic examination of tumor sections from FL-treated mice revealed regions of solid tumor growth with glandular architecture similar to that seen in control tumors; however, there was an obvious increase in regions composed largely of dense fibrosis in the FL-treated tumors. NK cells and other infiltrating cells could be detected in clusters among tumors from mice treated with FL whereas these cells were only occasionally detected in sections of control tumors. CONCLUSION: FL treatment resulted in an antitumor response against human ovarian cancer engrafted in SCID mice and this inhibition appears to be largely host NK cell mediated. The tumor inhibition seen in this model is similar to that previously seen using syngeneic tumors grown in an immunocompetent animal model. Results from this model can potentially be extrapolated to treatment of human ovarian cancer patients.     

Ovarian carcinoma cell cultures are resistant to TGF-beta1-mediated growth inhibition despite expression of functional receptors.

OBJECTIVE: The purpose of this study was to determine the response of ovarian carcinoma cells to TGF-beta1 and to examine components of the TGF-beta signaling pathway. METHODS: Twenty-three primary ovarian cancer cell (CSOC) cultures established from solid ovarian carcinomas were treated with TGF-beta1 and assayed for growth response by MTT assay. Expression of TGF-beta receptor I (TbetaR-I) and receptor II (TbetaR-II), essential for effective signaling, was determined by Western analysis of CSOC cultures. TGF-beta1 ligand-induced phosphorylation of TbetaR-I was determined by immunoprecipitation of TbetaR-I followed by a protein kinase assay to assess TbetaR-I phosphorylation, an essential first step in TGF-beta signal transduction. Gelatin zymography performed on 5 CSOC cultures incubated with TGF-beta1 was used to determine TGF-beta's effect on matrix metalloproteinase production. Normal ovarian surface epithelial cells were used for comparison. RESULTS: Eighteen of twenty-three (78%) CSOC cultures demonstrated no significant growth inhibition in response to TGF-beta1 treatment. All cell cultures expressed TbetaR-I and TbetaR-II and exhibited TbetaR-I phosphorylation following TGF-beta1 treatment. CSOC cultures produced significantly higher levels of matrix metalloproteinase-2 (MMP-2) than normal ovarian surface epithelial cells; however, the level of MMP-2 expression was not regulated by TGF-beta1. CONCLUSION: These results indicate that TGF-beta1 resistance and higher levels of MMP-2 production may be inherent properties of the ovarian cancer phenotype. The initial steps in the TGF-beta signaling pathway, receptor expression, ligand binding, and TbetaR-I phosphorylation, appear to be functional in primary ovarian cancer cell cultures. Therefore, the mechanism of growth resistance is downstream of TbetaR-I phosphorylation.     

Effects of a combined treatment with mTOR inhibitor RAD001 and tamoxifen in vitro on growth and apoptosis of human cancer cells

OBJECTIVE: Interactions between estrogen receptor signaling and the PI3K/Akt pathway are present in estrogen-dependent cancer cells. Therapeutical inhibition of each of these pathways has been proven to exert antitumoral effects. Inhibition of mammalian target of rapamycin (mTOR), a downstream target of Akt, is able to restore tamoxifen response in tamoxifen-resistant breast cancer cells. Given that Akt and mTOR phosphorylation also is frequently detected in ovarian and endometrial cancer, we intended to find out to what extent mTOR inhibitor RAD001 (everolimus) and tamoxifen add to each other's effects on growth and apoptosis of cancer cell lines derived from these tissues when given concomitantly. METHODS: OVCAR-3 and SK-OV-3 ovarian cancer cells, HEC-1A endometrial adenocarcinoma cells and MCF-7 breast cancer cells were treated with different concentrations of mTOR inhibitor RAD001 alone or in combination with 4-OH tamoxifen. Relative numbers of viable cells were assessed by means of the resazurin-based Cell Titer Blue assay, cellular apoptosis was examined by measurement of activated caspases 3 and 7 by means of the luminometric Caspase-Glo assay. RESULTS: Treatment with RAD001 resulted in growth inhibition of all employed cancer cell lines in a dose-dependent manner, and SK-OV-3 ovarian cancer cells proved to be most sensitive to this drug. Moreover, we report the observation of additive, but not synergistical growth inhibitory effects of a combination treatment with RAD001 and 4-OH TAM on SK-OV-3 and OVCAR-3 ovarian cancer cells and MCF-7 breast cancer cells in vitro, whereas no such effect was observed in HEC-1A endometrial adenocarcinoma cells. Combination treatment with both drugs was demonstrated to be superior to single treatment with lower concentrations (0.1 and 1 nM) of RAD001 or standard concentrations of 4-OH TAM. Furthermore, RAD001 increased the apoptotic effect triggered by high 4-OH TAM concentrations in SK-OV-3 ovarian cancer cells. CONCLUSION: Combination treatment with RAD001 and 4-OH TAM in vitro exerts an additive antitumoral effect on ovarian cancer cells and MCF-7 breast cancer cells. The significance of these data in the clinical situation has to be evaluated in further studies.     

Study of the inhibitory effects of retrovirus-mediated p16 gene on human ovarian cancer cell line

OBJECTIVE: To study the inhibitory effects of retro-virus-mediated p16 gene on human ovarian cancer cell line CAOV3. METHODS: Recombinant eukaryotic expression vector pDOR-p16 containing exogenous human wt-p16 cDNA and vector with neomycin resistance gene only were introduced by lipofectamine-mediated gene transfection into CAOV3 cell line which does not express p16 endogenously. By using revert-polymerase chain reaction amplification, mRNA in situ hybridization and immunocytochemistry, the clones obtained were detected for their efficiency of transfection and effects of vector expression and observed for their biologic behavior. RESULTS: Exogenous wt-p16 had successfully been transferred into CAVO3 cells and obtained permanent expression. The growth rate of these transfected CAOV3 cells in regular medium and soft agar was inhibited, and the tumorigenicity in nude mice showed that two in four mice failed to form tumor and the others suffered from tumor later than contrast group by 7 to 14 days. The percentage of phase G1 cells increased and that of phase S cells decreased by analysing cell cycle. The ultrastructural changes of the cells were observed under electron microscope, revealing necrosis and growth retardation. CONCLUSIONS: p16 gene played an important role in generation and development of ovarian carcinoma. This study might provide the experimental evidence for the gene therapy in human ovarian cancer.     

Inhibition of epithelial ovarian cancer by Minnelide,a water-soluble pro-drug

Objective

Minnelide is a water-soluble pro-drug of triptolide, a natural product. The goal of this study was to evaluate the effectiveness of Minnelide on ovarian cancer growth in vitro and in vivo.

Methods

The effect of Minnelide on ovarian cancer cell proliferation was determined by real time electrical impedance measurements. Multiple mouse models with C200 and A2780 epithelial ovarian cancer cell lines were used to assess the efficacy of Minnelide in inhibiting ovarian cancer growth.

Results

Minnelide decreased cell viability of both platinum sensitive and resistant epithelial ovarian cancer cells in vitro. Minnelide with carboplatin showed additive effects in vitro. Minnelide monotherapy increased the survival of mice bearing established ovarian tumors. Minnelide, in combination with carboplatin and paclitaxel, improved overall survival of mice.

Conclusions

Minnelide is a promising pro-drug for the treatment of ovarian cancer, especially when combined with standard chemotherapy.     

Effect of carbon dioxide on human ovarian carcinoma cell growth

OBJECTIVE: Laparoscopy may be associated with increased risk of ovarian carcinoma wound metastases. This study was designed to determine whether carbon dioxide exposure increases the growth of human ovarian cancer cells in vitro. STUDY DESIGN: Immortalized ovarian epithelial carcinoma cell (SKOV-3 cell line) cultures were exposed to carbon dioxide, nitrous oxide, or culture media with decreased pH for up to 3 hours. Cell growth was determined with the use of a spectrophotometric assay, and the results were compared with control cells by paired t tests and linear regressions analysis. RESULTS: Carbon dioxide exposure increased SKOV-3 cell growth by 52% after 4 days in culture. The increased cell growth had a linear relationship to the length of carbon dioxide exposure. Cells that were exposed to either nitrous oxide or media with pH 6.3 showed a trend toward decreased growth. CONCLUSION: Carbon dioxide exposure increases the in vitro growth of human ovarian carcinoma cells by an effect that is independent of the carbon dioxide-related decrease in the culture media pH.     

Studies on the molecular mechanism of growth inhibition with p53 adenoviral construct in human ovarian cancer

Mujoo K, Catino JJ, Maneval DC, Gutterman JU. Studies on the molecular mechanism of growth inhibition with p53 adenoviral construct in human ovarian cancer. Int J Gynecol Cancer 1998; 8 : 233–241.
Advanced stage human ovarian cancer exhibits 50–60% mutation of the p53 tumor suppressor gene. We introduced the wild-type p53 gene into the cells using a replication deficient recombinant adenovirus for p53 gene therapy. p53-adenovirus (rAd-p53) inhibited the growth of a number of ovarian cancer cells, which correlated well with the transduction of adenovirus containing β-galactosidase reporter gene in the tested cell lines. Results presented herein demonstrate that p53 induced the expression of CDK inhibitor WAF1/CIP1/p21 in human ovarian cancer cells with null or mutant p53. p53 incorporation also induced the expression of mdm-2 and bax proteins in human ovarian cancer cells. In contrast, we were unable to detect the expression of bcl-2 protein in the tested cells, and the expression bcl-x_L in the tested human ovarian cells was not altered post-infection of cells with rAd-p53. Cell cycle analysis revealed pronounced G1 arrest 24 h post-infection with rAd-p53 in human ovarian cancer cells with only a small percentage of cells (−2%) undergoing apoptosis. rAd-p53 (p53-adenovirus) inhibited the growth of established subcutaneous xenograft tumors (OVCAR-3) of human ovarian carcinoma and completely regressed the tumors in 5/8 mice, indicating a potential for p53 tumor suppressor gene therapy in human ovarian cancer.     

Dual targeting of angiotensin receptors (AGTR1 and AGTR2) in epithelial ovarian carcinoma

Objective

The renin–angiotensin system (RAS) influences cardiovascular homeostasis, and Angiotensin II type 1 receptor (AGTR1) is the main effector of RAS, and AGTR2 antagonizes AGTR1. Accumulating evidence supports the role of RAS in the paracrine regulation of tumorigenesis in several cancer types. Although treatment with AGTR1 antagonist (losartan) or AGTR2 agonist (CGP42112A) inhibits tumor progression in several cancer cells, their combined treatment has not been reported.

Methods

In this study, we estimated the expression of AGTR1 and AGTR2 in epithelial ovarian cancer cells and tissues. Then, we evaluated the anti-cancer effects of combined treatment with losartan and/or CGP42112A in ovarian cancer cells and human umbilical vein endothelial cells (HUVEC).

Results

AGTR1 protein was detected in 86% of ovarian cancer tissues, while AGTR2 was not detected in immunohistochemistry. The mRNA expression of AGTR1 obtained from the cancer genome atlas (TCGA) dataset showed that AGTR1 overexpression was correlated with poor survival. Treatment with either losartan or CGP42112A reduced the angiotensin II (Ang II)-mediated cell survival in both ovarian cancer cells and HUVEC. Combined treatment with losartan and CGP42112A synergistically decreased cell survival. As a downstream pathway, phosphorylation of phospholipase C β3 (PLC β3) and expression of vascular endothelial growth factor (VEGF) decreased synergistically in combined treatment.

Conclusion

The results suggest that dual regulation of AGTR1 and AGTR2 may be a novel therapeutic strategy for epithelial ovarian carcinoma through inhibition of cancer cell survival as well as anti-angiogenesis.

Translational relevance

This study investigated the expressions of AGTR1 and AGTR2 in epithelial ovarian carcinoma and the therapeutic potential of AGTR modulation with specific antagonist and/or agonist in epithelial ovarian cancer cells. Treatment of AGTR1 antagonist, losartan and/or AGTR2 agonist, CGP42112A synergistically mediated anti-cancer effects including the decrease of cell survival and down-regulation of VEGF.