Xenograft Model Of Human Ovarian Carcinoma Research Articles

Discovery of a Chemical Probe Bisamide (CCT251236): An Orally Bioavailable Efficacious Pirin Ligand from a Heat Shock Transcription Factor 1 (HSF1) Phenotypic Screen.

Phenotypic screens, which focus on measuring and quantifying discrete cellular changes rather than affinity for individual recombinant proteins, have recently attracted renewed interest as an efficient strategy for drug discovery. In this article, we describe the discovery of a new chemical probe, bisamide (CCT251236), identified using an unbiased phenotypic screen to detect inhibitors of the HSF1 stress pathway. The chemical probe is orally bioavailable and displays efficacy in a human ovarian carcinoma xenograft model. By developing cell-based SAR and using chemical proteomics, we identified pirin as a high affinity molecular target, which was confirmed by SPR and crystallography.

Abstract 3916: HSP90 mediates tumor-associated matrix metalloproteinase 2 and Cathepsin L protease activities in ovarian carcinoma

Abstract Ovarian cancer is the fifth leading cause of cancer-related deaths among women in the United States. At diagnosis, disease has commonly spread beyond the ovary. Ovarian cancer cells dislodge from primary tumor and spread locally throughout the abdominal cavity and lymphatics. Cancer cell shedding and colonization at other sites involves the degradation of extra cellular matrix (ECM) by tumor-associated proteases, such as matrix metalloproteinase (MMPs) and cathepsin proteases. Heat shock protein 90 (HSP90) is an ATP-dependent molecular chaperone that interacts with and stabilizes MMPs in some solid tumors. Whether HSP90 regulates cathepsin activity is currently unknown. To determine the role of HSP90 on tumor-associated MMP and cathepsin protease activities in ovarian carcinoma, HSP90 activity was inhibited using pharmacologic and RNA interference (RNAi) approaches. A small molecule inhibitor, ganetespib, and two HSP90 targeting siRNAs were used to determine the effects of HSP90 inhibition on ovarian carcinoma cell line invasion using transwell and spheroid invasion assays. The effects of ganetespib or HSP90 targeting siRNA treatment on MMP and cathepsin protease activities were assayed by gelatin zymography (MMPs), enzyme assay (cathepsins) and by dynamic imaging using protease cleavable imaging probes. The effects of ganetespib treatment on in vivo orthotopic tumor growth, dissemination and tumor associated protease activities were determined using human ovarian carcinoma xenograft models. In vitro, ganetespib treatment or expression of HSP90-targeted siRNAs inhibited transwell and spheroid invasion, and MMP-2 and cathepsin L protease activities. In vivo, ganetespib treatment resulted in decreased growth of primary tumors and disseminated tumor nodules and decreased tumor-associated MMP and cathepsin activities. Importantly, significant inhibition of MMP and cathepsin activities was detected prior to differences in tumor volume, demonstrating rapid functional response to the drug. These results show that HSP90 regulates ovarian carcinoma-associated proteolytic activities that are essential to tumor progression and dissemination. They also point to the potential utility of HSP90 inhibition as a therapeutic strategy for the treatment of ovarian cancer. Citation Format: Shane W. O'Brien, Fang Xiao, Marsia A. Maglaty, Joshua S. Trinadad, Lainie P. Martin, David A. Proia, Denise C. Connolly. HSP90 mediates tumor-associated matrix metalloproteinase 2 and Cathepsin L protease activities in ovarian carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3916. doi:10.1158/1538-7445.AM2014-3916

Vascular Endothelial Growth Factor C Promotes Ovarian Carcinoma Progression through Paracrine and Autocrine Mechanisms

Vascular endothelial growth factor C (VEGFC) has been reported to promote tumor progression in several tumor types, mainly through the stimulation of lymphangiogenesis and lymphatic metastasis. However, the expression and biological significance of the VEGFC/VEGF receptor (VEGFR)-3 pathway in ovarian cancer growth and dissemination are unclear, and have been investigated in this study. Soluble VEGFC was detected in the plasma and ascites of patients with ovarian carcinoma, and VEGFR3 expression was found in their tumor tissues. In human ovarian carcinoma xenograft models, high levels of soluble VEGFC in ascites and serum were detected, in association with disease progression, tumor burden, and volume of ascites. Peak VEGFC expression preceded para-aortic lymph node infiltration by HOC8 neoplastic cells. Histological detection of tumor cells in blood and lymphatic vessels indicated both hematogenous and lymphatic dissemination. Overexpression of VEGFC in the VEGFR3-positive and luciferase-expressing IGROV1 cells promoted carcinoma dissemination after orthotopic transplantation in the ovary of immunodeficient mice. In vitro, VEGFC released by the tumor cells stimulated tumor cell migration in an autocrine manner. Cediranib, an inhibitor of VEGFR1-3 and c-kit, inhibited in vivo metastasis of VEGFC-overexpressing IGROV1 and in vitro autocrine effects. These findings suggest that the VEGFC/VEGFR3 pathway acts as an enhancer of ovarian cancer progression through autocrine and paracrine mechanisms, hence offering a potential target for therapy.

A novel antibody-like TCRγδ-Ig fusion protein exhibits antitumor activity against human ovarian carcinoma

TCRγ9δ2(OT3) is a tumor-specific TCR with an unique complementarity-determining region 3 (CDR3) sequence, referred to as OT3, in its δ2 chain. This region was identified in tumor-infiltrating lymphocytes (TILs) from human ovarian epithelial carcinoma. We demonstrated that TCRγ9δ2(OT3)-Fc, a fusion protein composed of the complete extracellular domains of the γ9 and δ2 chains linked to the Fc domains of human IgG1, exhibited successful binding to multiple human carcinoma cell lines. In vitro, TCRγ9δ2(OT3)-Fc mediated cell killing via antibody-dependent cellular cytotoxicity (ADCC) in a dose-dependent manner. In vivo, TCRγ9δ2(OT3)-Fc significantly inhibited tumor growth and enhanced survival in human ovarian carcinoma xenograft models. Our findings suggest that the TCRγ9δ2(OT3)-Fc fusion protein possesses both the antigen-recognition properties of TCR γδ and the Fc-mediated effector functions of the antibody.

Genetically modified macrophages expressing hypoxia regulated cytochrome P450 and P450 reductase for the treatment of cancer

This study describes a combined gene and cell therapy based on the genetic modification of primary human macrophages, as a treatment for cancer. Here, we have utilised the tumour-infiltrating properties of macrophages as vehicles to deliver a gene encoding a prodrug-activating enzyme such as human cytochrome P450 2B6 (CYP2B6) inside tumours followed by killing the tumour cells with the prodrug cyclophosphamide (CPA). Macrophages were transduced with an adenoviral vector that expresses human cytochrome CYP2B6 via a synthetic hypoxia responsive promoter (OBHRE) and with human P450 reductase (P450R), via the CMV promoter. In the presence of CPA, these genetically modified macrophages showed increased cytotoxicity against various tumour cell lines compared to untransduced macrophages or macrophages transduced with CYP2B6 alone. In human ovarian carcinoma xenograft models, the median survival of mice treated with genetically modified macrophages plus CPA increased up to two-fold compared to the survival of mice treated with untransduced macrophages and CPA. Genetically modified autologous macrophages may be a feasible therapeutic option for the treatment of some solid tumours, such as ovarian cancer.

Magnetic vectoring of magnetically responsive nanoparticles within the murine peritoneum

Magnetically responsive nanoparticles (MNPs) might be candidates for pro-drug formulations for intraperitoneal (i.p.) treatment of ovarian cancer. We conducted feasibility experiments in an i.p. human ovarian carcinoma xenograft model to determine whether MNPs can be effectively vectored within this environment. Our initial results based on magnetic resonance imaging (MRI) indicate that i.p.-injected ∼15 nm magnetite-based MNPs can in fact migrate toward NdFeB magnets externally juxtaposed to the peritoneal cavity above the xenografts growing in the anterior abdominal wall. MNP localization to the tumor/peri-tumoral environment occurs. Further development of this MNP pro-drug strategy is underway.

N-(cycloalkylamino)acyl-2-aminothiazole inhibitors of cyclin-dependent kinase 2. N-[5-[[[5-(1,1-dimethylethyl)-2-oxazolyl]methyl]thio]-2-thiazolyl]-4- piperidinecarboxamide (BMS-387032), a highly efficacious and selective antitumor agent.

N-Acyl-2-aminothiazoles with nonaromatic acyl side chains containing a basic amine were found to be potent, selective inhibitors of CDK2/cycE which exhibit antitumor activity in mice. In particular, compound 21 [N-[5-[[[5-(1,1-dimethylethyl)-2-oxazolyl]methyl]thio]-2-thiazolyl]-4-piperidinecarboxamide, BMS-387032], has been identified as an ATP-competitive and CDK2-selective inhibitor which has been selected to enter Phase 1 human clinical trials as an antitumor agent. In a cell-free enzyme assay, 21 showed a CDK2/cycE IC(50) = 48 nM and was 10- and 20-fold selective over CDK1/cycB and CDK4/cycD, respectively. It was also highly selective over a panel of 12 unrelated kinases. Antiproliferative activity was established in an A2780 cellular cytotoxicity assay in which 21 showed an IC(50) = 95 nM. Metabolism and pharmacokinetic studies showed that 21 exhibited a plasma half-life of 5-7 h in three species and moderately low protein binding in both mouse (69%) and human (63%) serum. Dosed orally to mouse, rat, and dog, 21 showed 100%, 31%, and 28% bioavailability, respectively. As an antitumor agent in mice, 21 administered at its maximum-tolerated dose exhibited a clearly superior efficacy profile when compared to flavopiridol in both an ip/ip P388 murine tumor model and in a s.c./i.p. A2780 human ovarian carcinoma xenograft model.

Comparison of paclitaxel and docetaxel activity on human ovarian carcinoma xenografts

The antitumour activity of paclitaxel (NSC 125973) and docetaxel (RP 56976, NSC 628503) was evaluated and compared against human ovarian carcinoma (HOC) xenografts in nude mice. Paclitaxel and docetaxel were given intravenously (i.v.) at a dose range of 16.6–34.5 mg/kg, once every 4 days for three consecutive doses to nude mice with HOC xenografts, transplanted subcutaneously (s.c.) (HOC18 and HOC22-S) or intraperitoneally (i.p.) (HOC8 and HOC22). Paclitaxel and docetaxel, at the highest dosage, induced complete tumour regression in 80–100% and 67% of mice bearing HOC22-S and HOC18 s.c., respectively. Both drugs cured 100% of mice bearing early stage HOC22 tumour in the peritoneal cavity, while treatment at an advanced stage significantly increased the survival time of all the mice. Both induced a 57% cure rate in mice bearing HOC8 in the peritoneal cavity. Paclitaxel and docetaxel were more effective than cisplatin (4 mg/kg, same dosing regime as above) used as a reference compound. These findings indicate that paclitaxel and docetaxel were highly active on four HOC xenograft models. No significant difference between them was detected in ovarian cancer xenografts.

Chemoimmunoconjugate development for ovarian carcinoma therapy: preclinical studies with vinca alkaloid-monoclonal antibody constructs.

Preclinical efficacy studies are presented in a human ovarian carcinoma model utilizing several novel conjugation strategies with the KS1/4 monoclonal antibody and derivatives of the vinca alkaloid desacetylvinblastine hydrazide. The chemoimmunoconjugates KS1/4-beta-alanine-methylenemalonic acid ethyl ester-4-decacetylvinblastine 23-hydrazide (KS1/4-BAMME-DAVLB-HY), KS1/4-beta-alanine-5-formylpyrrole-2-carboxylic acid-4-desacetylvinblastine 23-hydrazide (KS1/4-BAP-DAVLB-HY), and KS1/4-4-desacetylvinblastine 23-hydrazide were explored in the OVCAR-3 human ovarian carcinoma xenograft model. These conjugates, constructed with variable linker stability between the vinca alkaloid and the antibody, were studied by comparing the route of administration and the treatment schedule. Under these conditions a mean survival time from 28 to 35 days in untreated control animals was observed. Significant increases in survival (i.e. 3-9-fold over untreated control animals) were observed with all the immunoconjugates tested but with varying potency and efficacy dependent on linker strategy. Parallel therapy with equivalent doses of free DAVLB-HY or a non-antigen-binding immunoconjugate did not significantly increase the survival of the animals. These results suggest several chemoimmunoconjugate strategies for site-directed therapy of human ovarian cancer.

Evaluation of in vitro drug screening leads using experimental models of human ovarian cancer.

Five compounds which were identified as potential new anticancer drugs in in vitro screening with the human tumor colony forming assay were selected for further evaluation using in vitro and in vivo models of human ovarian cancer. Three of five compounds were found to inhibit in vitro colony formation of ovarian cancer cell lines derived from both untreated and combination chemotherapy refractory patients. One compound was also found to prolong survival in a human ovarian carcinoma xenograft model system. This compound, chloroquinoxaline sulfonamide, was selected for development and has shown preliminary indication of activity in phase I clinical testing.