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Low-dose glucocorticoids suppresses ovarian tumor growth and metastasis in an immunocompetent syngeneic mouse model.

ABSTRACT: Ovarian cancer has the highest mortality rate among gynecologic malignancies. Despite chemotherapy and surgical debulking options, ovarian cancer recurs and disseminates frequently with a poor prognosis. We previously reported a novel role of glucocorticoids (GCs) in metastatic ovarian cancer by upregulating microRNA-708. In this study, we used an immunocompetent syngeneic mouse model and further evaluated the effect and optimal dosages of GCs in treating metastatic ovarian cancer. The treatment of C57BL/6-derived ovarian cancer ID-8 cells with a synthetic GC, dexamethasone (DEX), induced the expression of microRNA-708, leading to decreased cell migration and invasion through targeting Rap1B. Administration of DEX at a low dose, as low as 5 ?g/kg body weight, inhibited the primary tumor size and abdominal metastasis in mice bearing ID-8 cell-derived ovarian tumors. In the treated primary tumors, microRNA-708 was upregulated, whereas some proinflammatory cytokines, namely interleukin (IL)-1? and IL-18, were downregulated. The number of tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment were reduced. Overall, our study shows that low-dose GCs can suppress ovarian cancer progression and metastasis likely through not only the upregulation of the metastasis suppressor microRNA-708, but also the modulation of TAMs and MDSCs in the tumor microenvironment.

SUBMITTER: Lin KT

PROVIDER: S-EPMC5462394 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Low-dose glucocorticoids suppresses ovarian tumor growth and metastasis in an immunocompetent syngeneic mouse model.

Lin Kai-Ti KT Sun Shu-Pin SP Wu Jui-I JI Wang Lu-Hai LH

PloS one 20170607 6

Ovarian cancer has the highest mortality rate among gynecologic malignancies. Despite chemotherapy and surgical debulking options, ovarian cancer recurs and disseminates frequently with a poor prognosis. We previously reported a novel role of glucocorticoids (GCs) in metastatic ovarian cancer by upregulating microRNA-708. In this study, we used an immunocompetent syngeneic mouse model and further evaluated the effect and optimal dosages of GCs in treating metastatic ovarian cancer. The treatment ...[more]

PMID: 28591224

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Project description:Limited diffusion of oxygen in combination with increased oxygen consumption leads to chronic hypoxia in most solid malignancies. This scarcity of oxygen is known to induce radioresistance and leads to an immunosuppressive microenvironment. Carbonic anhydrase IX (CAIX) is an enzyme functioning as a catalyzer for acid export in hypoxic cells and is an endogenous biomarker for chronic hypoxia. The aim of this study is to develop a radiolabeled antibody that recognizes murine CAIX to visualize chronic hypoxia in syngeneic tumor models and to study the immune cell population in these hypoxic areas. An anti-mCAIX antibody (MSC3) was conjugated to diethylenetriaminepentaacetic acid (DTPA) and radiolabeled with indium-111 (111In). CAIX expression on murine tumor cells was determined using flow cytometry, and in vitro affinity of [111In]In-MSC3 was analyzed in a competitive binding assay. Ex vivo biodistribution studies were performed to determine in vivo radiotracer distribution. CAIX+ tumor fractions were determined by mCAIX microSPECT/CT, and the tumor microenvironment was analyzed using immunohistochemistry and autoradiography. We showed that [111In]In-MSC3 binds to CAIX-expressing (CAIX+) murine cells in vitro and accumulates in CAIX+ areas in vivo. We optimized the use of [111In]In-MSC3 for preclinical imaging such that it can be applied in syngeneic mouse models and showed that we can quantitatively distinguish between tumor models with varying CAIX+ fractions by ex vivo analyses and in vivo mCAIX microSPECT/CT. Analysis of the tumor microenvironment identified these CAIX+ areas as less infiltrated by immune cells. Together these data demonstrate that mCAIX microSPECT/CT is a sensitive technique to visualize hypoxic CAIX+ tumor areas that exhibit reduced infiltration of immune cells in syngeneic mouse models. In the future, this technique may enable visualization of CAIX expression before or during hypoxia-targeted or hypoxia-reducing treatments. Thereby, it will help optimize immuno- and radiotherapy efficacy in translationally relevant syngeneic mouse tumor models.

Project description:BackgroundMost cases of ovarian cancer are epithelial in origin and diagnosed at advanced stage when the cancer is widely disseminated in the peritoneal cavity. The objective of this study was to establish an immunocompetent syngeneic mouse model of disseminated epithelial ovarian cancer (EOC) to facilitate laboratory-based studies of ovarian tumor biology and preclinical therapeutic strategies.MethodsIndividual lines of TgMISIIR-TAg transgenic mice were phenotypically characterized and backcrossed to inbred C57BL/6 mice. In addition to a previously described line of EOC-prone mice, two lines (TgMISIIR-TAg-Low) were isolated that express the oncogenic transgene, but have little or no susceptibility to tumor development. Independent murine ovarian carcinoma (MOVCAR) cell lines were established from the ascites of tumor-bearing C57BL/6 TgMISIIR-TAg transgenic mice, characterized and tested for engraftment in the following recipient mice: 1) severe immunocompromised immunodeficient (SCID), 2) wild type C57BL/6, 3) oophorectomized tumor-prone C57BL/6 TgMISIIR-TAg transgenic and 4) non-tumor prone C57BL/6 TgMISIIR-TAg-Low transgenic. Lastly, MOVCAR cells transduced with a luciferase reporter were implanted in TgMISIIR-TAg-Low mice and in vivo tumor growth monitored by non-invasive optical imaging.ResultsEngraftment of MOVCAR cells by i.p. injection resulted in the development of disseminated peritoneal carcinomatosis in SCID, but not wild type C57BL/6 mice. Oophorectomized tumor-prone TgMISIIR-TAg mice developed peritoneal carcinomas with high frequency, rendering them unsuitable as allograft recipients. Orthotopic or pseudo-orthotopic implantation of MOVCAR cells in TgMISIIR-TAg-Low mice resulted in the development of disseminated peritoneal tumors, frequently accompanied by the production of malignant ascites. Tumors arising in the engrafted mice bore histopathological resemblance to human high-grade serous EOC and exhibited a similar pattern of peritoneal disease spread.ConclusionsA syngeneic mouse model of human EOC was created by pseudo-orthotopic and orthotopic implantation of MOVCAR cells in a susceptible inbred transgenic host. This immunocompetent syngeneic mouse model presents a flexible system that can be used to study the consequences of altered gene expression (e.g., by ectopic expression or RNA interference strategies) in an established MOVCAR tumor cell line within the ovarian tumor microenvironment and for the development and analysis of preclinical therapeutic agents including EOC vaccines and immunotherapeutic agents.

Dataset Information

Low-dose glucocorticoids suppresses ovarian tumor growth and metastasis in an immunocompetent syngeneic mouse model.

Publications

Low-dose glucocorticoids suppresses ovarian tumor growth and metastasis in an immunocompetent syngeneic mouse model.

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