Peritoneal Dissemination Of Ovarian Cancer Research Articles

A Strategy Using Photodynamic Therapy and Clofibric Acid to Treat Peritoneal Dissemination of Ovarian Cancer

The current study examined the effectiveness of concurrent therapy using photodynamic therapy (PDT) and clofibric acid (CA) to treat peritoneal carcinomatosis resulting from ovarian cancer. Nude rats were used to create a model of peritoneal carcinomatosis resulting from ovarian cancer and the effectiveness of PDT with 5-aminolevulinic acid methyl ester hydrochloride (methyl-ALA-PDT) was determined. The survival time of rats receiving that therapy was compared to the survival time of a control group. Rats with peritoneal carcinomatosis resulting from ovarian cancer were divided into 3 groups: a group that received debulking surgery (DS) alone, a group that received DS+methyl-ALA-PDT, and a group that received DS+methyl-ALA-PDT+CA. The survival time of the 3 groups was compared. Protoporphyrin, a metabolite of methyl-ALA, produces a photochemical action when activated by light. The level of protoporphyrin (the concentration) that reached organs in the abdomen was measured with HPLC. Rats receiving methyl- ALA-PDT had a significantly longer survival time compared to the controls. Rats with peritoneal carcinomatosis that received DS+methyl-ALA-PDT+CA had a significantly longer survival time compared to the rats that received DS alone. Some of the rats that received concurrent therapy survived for a prolonged period. Protoporphyrin was highly concentrated in peritoneal metastases, but only small amounts reached major organs in the abdomen. PDT was not found to result in necrosis in the intestines. The results indicated that concurrent therapy consisting of PDT with methyl-ALA and CA is effective at treating peritoneal carcinomatosis resulting from ovarian cancer without damaging organs.

Abstract A56: Inhibition of Snail-induced EMT promotes anti-tumor immune response in ovarian cancer.

Abstract Background: Peritoneal dissemination is a common mode of tumor progression in ovarian cancer, and one of the most important unfavorable prognostic factors. Epithelial-mesenchymal transition (EMT) has been indicated to be a key process in tumor invasion and metastasis. Recent studies demonstrate that EMT suppresses anti-tumor immunity in some types of cancer. The aim of the current study is to elucidate the relationship between EMT-related gene Snail and local immunity in ovarian cancer. Methods: The expression of Snail and patient survival was analyzed in two microarray datasets, TCGA, and KOV75 (75 ovarian cancer cases operated in our department). Using mouse ovarian cancer cell line HM-1, the influence of Snail expression on EMT, peritoneal dissemination, survival, and local immunity was analyzed using both in vitro and in vivo models. Snail-silenced cell line, HM1-sh-snail was established, and compared with the control HM-1. Results: Among 4 subtypes of high grade serous ovarian cancer, Mesenchymal subtype, which show marked stromal reaction in histopathology, shows the worst prognosis (TCGA, KOV75). Snail expression was significantly high in Mesenchymal subtype (TCGA, p<0.0001; KOV75, p<0.05). High Snail expression was significantly related to short overall survival in TCGA (p<0.05). In HM1-sh-snail, expression of vimentin and fibronectin was decreased in RT-PCR analysis. Cell migration was inhibited in wound-healing assay (p<0.001), but the cell proliferation was not altered in WST assay. In mouse peritoneal dissemination model, HM1-sh-snail group demonstrated longer survival than the control group (p<0.05). In mouse subcutaneous tumor model, HM-1-sh-snail group revealed smaller tumor than the control group (p<0.05), although there was no difference between two groups in nude mouse model. Flow cytometric analysis of mouse tumors revealed that infiltration of CD4+ T cells and CD8+ T cells were all increased and MDSCs were decreased in HM1-sh-snail group. Conclusion: Snail-induced EMT inhibits local immune reaction and promotes peritoneal dissemination in ovarian cancer. Snail may be a potential therapeutic target in ovarian cancer. Citation Format: Mana Taki, Kaoru Abiko, Noriomi Matsumura, Tsukasa Baba, Junzo Hamanishi, Naoki Horikawa, Ikuo Konishi. Inhibition of Snail-induced EMT promotes anti-tumor immune response in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A56.

Abstract 3241: Tumor-targeting Salmonella typhimurium A1-R inhibits peritoneal dissemination of ovarian cancer and prolongs survival of the tumor-bearing nude mice

Abstract Peritoneal dissemination of cancer arising from an intra-abdominal organ has poor prognosis and is treatment resistant. A peritoneal dissemination nude mouse model of ovarian cancer was made with the human ovarian cancer cell line SKOV-3-GFP. Tumor-targeting Salmonella typhimurium A1-R (A1-R) was administrated i.v. or i.p. to the tumor-bearing nude mice. Survival of the tumor-bearing nude mice was prolonged by i.v. administration of A1-R (p = 0.025) as well as by i.p. administration of A1-R (p = 0.00003), compared with the untreated control. There was no significant difference in survival between i.v. and i.p. administration (p = 0.22). However, i.p. administration was less toxic. The present results suggest A1-R has clinical potential for what is currently a highly-treatment-resistant disease. Citation Format: Yasunori Matsumoto, Shinji Miwa, Ming Zhao, Yong Zhang, Shuya Yano, Fuminari Uehara, Mako Yamamoto, Yukihiko Hiroshima, Makoto Toneri, Michael Bouvet, Hisahiro Matsubara, Robert Hoffmann. Tumor-targeting Salmonella typhimurium A1-R inhibits peritoneal dissemination of ovarian cancer and prolongs survival of the tumor-bearing nude mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3241. doi:10.1158/1538-7445.AM2015-3241

The Risk of Ovarian Malignancy Algorithm (ROMA) as a Predictive Marker of Peritoneal Dissemination in Epithelial Ovarian Cancer Patients

Background: This study aimed to determine the efficacy of the risk of ovarian malignancy algorithm (ROMA), calculated using the carbohydrate antigen 125 (CA125) and human epididymis protein 4 (HE4) levels and the menopausal status, as a predictor of peritoneal dissemination in ovarian cancer. Methods: The CA125 and HE4 levels and the ROMA were compared between ovarian cancer patients (n = 122) with or without peritoneal dissemination. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated, and the results were compared with those of computed tomography (CT). Results: The CA125, HE4, and ROMA values differed significantly depending on the presence of peritoneal dissemination (p < 0.0001). The cut-off values were 181 U/ml for CA125, 161 pmol/ml for HE4, 44% for the ROMA (premenopausal), and 86% for the ROMA (postmenopausal). Among these markers, the ROMA (premenopausal) was the strongest predictor of peritoneal dissemination, with a specificity of 85.0% and a positive predictive value of 81.3%. In addition, the detection rates of small disseminations with less than 2 cm in diameter for the ROMA (93%) and HE4 (60%) were superior to that of CT (53%). Conclusions: The ROMA was a significant predictor of peritoneal dissemination and may be superior to CT for the detection of patients with small disseminations.

Systematic evaluation of vascular endothelial growth factor receptor expression in primary ovarian cancer and its clinical relevance

Objectives: The identification of novel molecular biomarkers, predicting outcome of ovarian cancer, is highly desirable. Considering that angiogenesis is a critical factor for ascites development and peritoneal dissemination in ovarian cancer and given that the vascular endothelial growth factor (VEGF) receptor signaling axis is a major driver of angiogenesis, we sought to analyze expression and compartmental distribution of VEGF-receptor family in ovarian cancer and to assess its clinical relevance with regard to established clinicopathological parameters, tumor cell dissemination to the bone marrow (BM) and the patient's survival.

Indoleamine 2,3-dioxygenase promotes peritoneal metastasis of ovarian cancer by inducing an immunosuppressive environment.

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-catabolizing enzyme that has immunoregulatory functions. Our prior study showed that tumoral IDO overexpression is involved in disease progression and impaired patient survival in human ovarian cancer, although its mechanism remains unclear. The purpose of the present study is to clarify the role of IDO during the process of peritoneal dissemination of ovarian cancer. Indoleamine 2,3-dioxygenase cDNA was transfected into the murine ovarian carcinoma cell line OV2944-HM-1, establishing stable clones of IDO-overexpressing cells (HM-1-IDO). Then HM-1-IDO or control vector-transfected cells (HM-1-mock) were i.p. transplanted into syngeneic immunocompetent mice. The HM-1-IDO-transplanted mice showed significantly shortened survival compared with HM-1-mock-transplanted (control) mice. On days 11 and 14 following transplantation, the tumor weight of peritoneal dissemination and ascites volume were significantly increased in HM-1-IDO-transplanted mice compared with those of control mice. This tumor-progressive effect was coincident with significantly reduced numbers of CD8+ T cells and natural killer cells within tumors as well as increased levels of transforming growth factor-β and interleukin-10 in ascites. Finally, treatment with the IDO inhibitor 1-methyl-tryptophan significantly suppressed tumor dissemination and ascites with reduced transforming growth factor-β secretion. These findings showed that tumor-derived IDO promotes the peritoneal dissemination of ovarian cancer through suppression of tumor-infiltrating effector T cell and natural killer cell recruitment and reciprocal enhancement of immunosuppressive cytokines in ascites, creating an immunotolerogenic environment within the peritoneal cavity. Therefore, IDO may be a promising molecular target for the therapeutic strategy of ovarian cancer.

Explorative investigation of vascular endothelial growth factor receptor expression in primary ovarian cancer and its clinical relevance

ObjectivesThe identification of novel molecular biomarkers, predicting outcome of ovarian cancer, is highly desirable. Considering that angiogenesis is a critical factor for ascites development and peritoneal dissemination in ovarian cancer and given that the vascular endothelial growth factor (VEGF) receptor signaling axis is a major driver of angiogenesis, we sought to analyze expression and compartmental distribution of VEGF-receptor family in ovarian cancer and to assess its clinical relevance with regard to established clinicopathological parameters, tumor cell dissemination to the bone marrow (BM) and the patient's survival. MethodsA total of 73 patients with primary ovarian cancer were enrolled into this study. Primary tumor tissue was analyzed for the expression of VEGF-R1, VEGF-R2 and VEGF-R3 by immunohistochemistry. The presence of disseminated tumor cells (DTC) in the BM was analyzed by immunocytochemistry using the pancytokeratin antibody A45B/B3 and subsequent automatic detection based on staining and cytomorphology. ResultsIn primary ovarian cancer tissue, VEGF-receptor expression, detected with an overall frequency of 44%, was mostly located in the vascular wall and across the stroma; positivity rates for VEGF-R1, VEGF-R2 and VEGF-R3 were 34%, 18% and 26%, respectively. Total VEGF-receptor expression correlated with residual tumor after primary debulking surgery and the presence of DTC at primary diagnosis (p=0.035, p=0.023, respectively). Interestingly, VEGF-R1 positivity significantly correlated with decreased progression-free survival (p=0.026). ConclusionsThis is the first report, suggesting total VEGF-receptor status as a molecular biomarker for monitoring tumor cell spread to the BM and, particularly, revealing prognostic significance of VEGF-R1.

The Parity-Associated Microenvironmental Niche in the Omental Fat Band Is Refractory to Ovarian Cancer Metastasis

Ovarian cancer is an insidious and aggressive disease of older women, typically undiscovered before peritoneal metastasis due to its asymptomatic nature and lack of early detection tools. Epidemiologic studies suggest that child-bearing (parity) is associated with decreased ovarian cancer risk, although the molecular mechanisms responsible for this phenomenon have not been delineated. Ovarian cancer preferentially metastasizes to the omental fat band (OFB), a secondary lymphoid organ that aids in filtration of the peritoneal serous fluid (PSF) and helps combat peritoneal infections. In the present study, we assessed how parity and age impact the immune compositional profile in the OFB of mice, both in the homeostatic state and as a consequence of peritoneal implantation of ovarian cancer. Using fluorescence-activated cell sorting analysis and quantitative real-time PCR, we found that parity was associated with a significant reduction in omental monocytic subsets and B1-B lymphocytes, correlating with reduced homeostatic expression levels of key chemoattractants and polarization factors (Ccl1, Ccl2, Arg1, and Cxcl13). Of note, parous animals exhibited significantly reduced tumor burden following intraperitoneal implantation compared with nulliparous animals. This was associated with a reduction in tumor-associated neutrophils and macrophages, as well as in the expression levels of their chemoattractants (Cxcl1 and Cxcl5) in the OFB and PSF. These findings define a preexisting "parity-associated microenvironmental niche" in the OFB that is refractory to metastatic tumor seeding and outgrowth. Future studies designed to manipulate this niche may provide a novel means to mitigate peritoneal dissemination of ovarian cancer.

Extracellular Tissue Transglutaminase Activates Noncanonical NF-κB Signaling and Promotes Metastasis in Ovarian Cancer

Tissue transglutaminase (TG2) is a multifunctional protein that binds to fibronectin and exerts protein transamidating activity in the presence of Ca2+. We previously reported that TG2 is upregulated in ovarian tumors and enhances intraperitoneal (i.p.) metastasis. TG2 is secreted abundantly in ovarian cancer (OC) ascites as an active enzyme, yet its function in the extracellular compartment remains unknown. To study the distinct functions of secreted TG2, we used recombinant His6-tagged TG2 and catalytically inactive enzyme in vitro and in vivo. By using i.p. and orthotopic ovarian xenografts, we show that extracellular transglutaminase promoted OC peritoneal metastasis. The main pathway activated by extracellular TG2 was noncanonical nuclear factor-kappa B (NF-κB) signaling, and the enzymatic function of the protein was required to induce phosphorylation of IκBkinaseá and processing of the precursor protein p100 into the active p52 subunit. A specific target of TG2-activated p52/RelB complex is the hyaluronan receptor, CD44. Noncanonical NF-κB activation by extracellular TG2 induced CD44 up-regulation and epithelial-to-mesenchymal transition, contributing to increased cancer cell invasiveness and OC peritoneal dissemination. Taken together, our data support that noncanonical NF-κB activation is the pathway through which extracellular TG2 promotes OC metastasis.

MiR-92a Inhibits Peritoneal Dissemination of Ovarian Cancer Cells by Inhibiting Integrin α5 Expression

Ovarian cancer is characterized by widespread peritoneal dissemination and ascites and has a cure rate of only 30%. As has been previously reported, integrin α5 plays a key role in the peritoneal dissemination of ovarian cancer. Our aim was to identify a new miRNA that regulates integrin α5 expression and analyze the therapeutic potential of targeting this miRNA. By using an IHC analysis, we proved that high integrin α5 expression correlates with a poor prognosis in Japanese patients with International Federation of Gynecology and Obstetrics stage III ovarian cancer. Based on an miRNA algorithm search, we identified hsa-mir-92a (miR-92a) as a candidate. The level of miR-92a expression was significantly inversely correlated with ITGA5 expression in various cancer cells. Transfection of precursor miR-92a reduced integrin α5 expression in ovarian cancer cells, which was accompanied by the inhibition of cancer cell adhesion, invasion, and proliferation. miR-92a overexpression reduced the luciferase activity of the ITGA5 3'-untranslated region, suggesting that ITGA5 mRNA is a direct target of miR-92a. In in vivo ovarian cancer xenografts, the enforced expression of miR-92a in HeyA-8 cells suppressed peritoneal dissemination. Although we still have a long way to go before an effective and nontoxic miRNA-based cancer therapy can be introduced into the clinic, the inhibition of integrin α5 expression by targeting miR-92a needs to be explored further for future applications in ovarian cancer treatment.

PD-L1 on Tumor Cells Is Induced in Ascites and Promotes Peritoneal Dissemination of Ovarian Cancer through CTL Dysfunction

Ovarian cancer often progresses by disseminating to the peritoneal cavity, but how the tumor cells evade host immunity during this process is poorly understood. Programmed cell death 1 ligand 1 (PD-L1) is known to suppress immune system and to be expressed in cancer cells. The purpose of this study is to elucidate the function of PD-L1 in peritoneal dissemination. Ovarian cancer cases were studied by microarray and immunohistochemistry. PD-L1 expression in mouse ovarian cancer cell line in various conditions was assessed by flow cytometry. PD-L1-overexpression cell line and PD-L1-depleted cell line were generated, and cytolysis by CTLs was analyzed, and alterations in CTLs were studied by means of timelapse and microarray. These cell lines were injected intraperitoneally to syngeneic immunocompetent mice. Microarray and immunohistochemistry in human ovarian cancer revealed significant correlation between PD-L1 expression and peritoneal positive cytology. PD-L1 expression in mouse ovarian cancer cells was induced upon encountering lymphocytes in the course of peritoneal spread in vivo and coculture with lymphocytes in vitro. Tumor cell lysis by CTLs was attenuated when PD-L1 was overexpressed and promoted when it was silenced. PD-L1 overexpression inhibited gathering and degranulation of CTLs. Gene expression profile of CTLs caused by PD-L1-overexpressing ovarian cancer was associated with CTLs exhaustion. In mouse models, PD-L1 depletion resulted in inhibited tumor growth in the peritoneal cavity and prolonged survival. PD-L1 expression in tumor cell promotes peritoneal dissemination by repressing CTL function. PD-L1-targeted therapy is a promising strategy for preventing and treating peritoneal dissemination.

Detecting peritoneal dissemination of ovarian cancer in mice by DWIBS

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is a relatively new diffusion-based pulse sequence that produces positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG)-like images. We tested the feasibility of DWIBS in detecting peritoneal ovarian cancer in a syngeneic mouse model. Female C57BL/6 mice were injected intraperitoneally with ID8 murine ovarian carcinoma cells. After 11 weeks, the abdomen was imaged by DWIBS. A respiratory gating diffusion-weighted spin-echo echo-planar imaging in abdomen was used (imaging parameters of field of view of 47×47 mm2, matrix size of 64×64 zero-filled to 256×256 and b-value of 1500 s/mm2). We also performed FDG microPET as the reference standard. For comparison of the correlating surface areas of tumor foci on both DWIBS and FDG microPET imaging, two-dimensional region-of-interest (ROI) analysis was performed, and correlation between the two modalities was determined. Mice were also subjected to macroscopic examination for tumor location and pathology after imaging. DWIBS in all mice depicted the tumors as abnormal high signal intensity. The results show that the ROI analysis of correlating lesions reveals relatively high correlation (r²=0.7296) and significant difference (P=.021) between DWIBS and FDG microPET. These results demonstrate that DWIBS has the potential for detecting peritoneal dissemination of ovarian cancer. Nonetheless, due to low ratios of image signal-to-noise and motion artifacts, DWIBS can be limited for lesions near the liver.

ASSOCIATION BETWEEN GROWTH FACTOR HEREGULIN -1^|^alpha; AND RECEPTORS IN GROWTH OF OVARIAN CANCER CELL LINE WITH HIGH POTENTIALITY OF PERITONEAL DISSEMINATION

Ovarian cancer, one of the poor-prognosis gynecological malignancies, is often associated with extensive peritoneal carcinomatosis when initially treated. The mechanism of the formation of peritoneal carcinomatosis from ovarian cancer is still unknown. It has been reported that overexpression of cancer-related growth factors and/or receptors may worsen the prognosis of diseases. In the previous paper, we had established the human ovarian serous adenocarcinoma cell lines from those with no potentiality of peritoneal dissemination (FOC-3) to high potentiality (MFOC-3), however, the mechanism of its phenotypical change remains unknown. In this paper, we compared these two cell lines for growth potential and the expression of growth factor heregulin (HRG)-1α and HER-2, HER-3, and HER-4 receptors. In addition, the effect of anti-receptor antibodies on cell growth was investigated. RT-PCR and Western blot analysis found the promotion of the expression of HRG precursor and HRG-1α in MFOC-3. Examination of the number of growing cells over time revealed a statistically significant increase in the number of cells in MFOC-3 compared with FOC-3. In a study using the addition of exogenous HRG-1α, no changes were observed in FOC-3 while statistically significant cell growth was noted in MFOC-3. In a growth inhibition study, statistically significant cell growth inhibition was achieved with the addition of anti-HER2 receptor antibody. Taken together, the results of this study suggested that HRG may play an important role in the increased growth potential of peritoneal dissemination of ovarian cancer. In particular, HER-2 receptors that can act as a starting point to trigger intracellular signaling pathways are strongly involved in the progression of cancer. Therefore, molecular target drug therapies blocking the HER-2 receptor are promising candidates for ovarian cancer treatment in the future.

Significance of vascular endothelial growth factor in growth and peritoneal dissemination of ovarian cancer.

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis which drives endothelial cell survival, proliferation, and migration while increasing vascular permeability. Playing an important role in the physiology of normal ovaries, VEGF has also been implicated in the pathogenesis of ovarian cancer. Essentially by promoting tumor angiogenesis and enhancing vascular permeability, VEGF contributes to the development of peritoneal carcinomatosis associated with malignant ascites formation, the characteristic feature of advanced ovarian cancer at diagnosis. In both experimental and clinical studies, VEGF levels have been inversely correlated with survival. Moreover, VEGF inhibition has been shown to inhibit tumor growth and ascites production and to suppress tumor invasion and metastasis. These findings have laid the basis for the clinical evaluation of agents targeting VEGF signaling pathway in patients with ovarian cancer. In this review, we will focus on VEGF involvement in the pathophysiology of ovarian cancer and its contribution to the disease progression and dissemination.

Abstract 799: Obesity-associated modulation of the immune microenvironment of the omental fat band during peritoneal seeding of ovarian cancer

Abstract Ovarian cancer is the leading cause of death by gynecological malignancy in the Western world, the fourth most deadly cancer in women. Typically originating from the layer of epithelial cells surrounding the ovary, cancer cells exfoliate to disseminate throughout the peritoneal cavity. The omental fat band (OFB) has been described as a secondary lymphoid organ composed of heavily vascularized fatty tissue interspersed with immune cell aggregates, or “milky spots”. It is also the site of preferential tumor cell adhesion and invasion within the peritoneal cavity, and is removed at the time of surgical debulking in ovarian cancer patients as a preventative measure. Several studies have suggested that obesity is a risk factor for ovarian cancer, but it is unclear whether the obese state directly influences peritoneal dissemination of ovarian cancer. Here, we set out to elucidate the obesity-related changes in the immune microenvironment of the OFB in the homeostatic state as well as following cancer cell adhesion and outgrowth. Our lab has developed a spontaneously transformed murine ovarian surface epithelial (MOSE) cell model that mimics the progressive stages of ovarian cancer following long-term passaging. Importantly, these cells can be used to study the immune microenvironment of tumor cells in an immunocompetent host. EGFP-expressing MOSE-L (late) cells that had been selected in vivo for an aggressive phenotype were injected i.p. into 6 month-old C57Bl/6 mice and changes to the OFB immune microenvironment were evaluated after 6, 24 hrs and 4 weeks. Furthermore, mice fed a high- or low-fat diet (40 or 5% calories as fat, respectively) were used to determine the effects of diet-induced obesity on cancer cell seeding and outgrowth. Immunofluorescence microscopy, real-time PCR and flow cytometry were used to determine tumor cell attachment and growth and identify changes in OFB immune cell populations. Early seeding (24 hrs post-injection) of EGFP-MOSE-L cells at the OFB was increased in high-fat fed mice. Preliminary data from mRNA expression profiling identified genes in the OFB that were i) obesity-associated, ii) a direct response to tumor cell seeding or iii) were exacerbated in the obese microenvironment following tumor cell seeding. This suggests that obesity-associated signaling events could be polarizing the OFB towards a pro-tumorigenic microenvironment. There were also distinct differences in the immune cell populations within the OFB as function of both obesity and time post-tumor cell seeding. These results indicate that ovarian cancer cells preferentially populate the OFB early during peritoneal dissemination and are capable of escaping immune surveillance mechanisms. This study sheds light on the obesity-induced changes in immunomodulatory events associated with tumor seeding and outgrowth in the peritoneal cavity. Supported by NIH CA118846 to EMS and PCR Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 799. doi:10.1158/1538-7445.AM2011-799

Abstract 1544: Identification of microRNA which regulates peritoneal dissemination of ovarian cancer

Abstract Ovarian cancer is highly metastatic and characterized by widespred peritoneal dissemination and massive ascites, and is the leading cause of death from gynecological malignancies. We have previously identified integrin α5 as a promising target for ovarian cancer treatment by inhibiting peritoneal dissemination. Our aim is to newly identify microRNAs which regulate integrin α5 expression and analyze the therapeutic potential of targeting those microRNAs. Based on the microRNA algorism search, we identified hsa-mira-92a as one of the candidates. Hsa-mir-92a is little expressed in ovarian cancer cells which express high level of integrin α5, whereas hsa-mir-92a is highly expressed in RMUG-S cells which hardly express integrin α5. Forced expression of mir-92a in ovarian cancer cell lines reduced integrin α5 expression in mRNA and protein level, accompanied by the inhibition of cell adhesion and invasion. On the contrary, the antagonist of mir-92a enhanced integrin α5 expression in RMUG-S cells. Luciferase assay revealed that mir-92a reduces the transcriptional activity of integrin α5 by directly binding ITGA5 3′-UTR. In vivo ovarian cancer xenografts, transducing hsa-mir-92a expressing plasmid into ovarian cancer cell lines significantly reduced peritoneal dissemination and ascites formation. Those results suggested targeting hsa-mir-92a could be a promising therapy for a subset of ovarian cancer patients by inhibiting integirn α5 expression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1544. doi:10.1158/1538-7445.AM2011-1544

Indoleamine 2,3-dioxygenase promotes peritoneal dissemination of ovarian cancer through inhibition of natural killercell function and angiogenesis promotion

The purpose of this study was to clarify the relationship between ovarian cancer peritoneal dissemination and indoleamine 2,3-dioxygenase (IDO) expression, and to explore the possibility of IDO-targeting molecular therapy for ovarian cancer. We transfected an IDO expression vector into the IDO-non-expressing human ovarian cancer cell line OMC-1, and established an IDO-expressing cell line (OMC-1/IDO) to examine the relationship between IDO expression and cancer cell growth in vitro and in vivo. IDO expression did not influence cancer cell growth and invasion in vitro, but promoted tumor growth and peritoneal dissemination in vivo. Immunostaining showed that IDO expression inhibited natural killer (NK) cell accumulation in tumors and promoted tumor angiogenesis. In addition, the oral administration of the IDO inhibitor 1-methly-tryptophan inhibited the growth of OMC-1/IDO-derived subcutaneous tumors in mice. These findings indicate that IDO promotes the peritoneal dissemination of ovarian cancer by inhibiting NK cell accumulation in tumors and promoting angiogenesis, supporting the applicability of IDO-targeting molecular therapy in ovarian cancer.

Targeting locoregional peritoneal dissemination in ovarian cancer

Ovarian carcinoma is the most lethal of the gynecological malignancies. This cancer is characterized by a high frequency of peritoneal dissemination resulting in significant morbidity and mortality, a situation unlike many other cancers. Together with resistance to chemotherapy, this locoregional peritoneal dissemination appears to be the major challenge and obstacle to improving outcomes in ovarian cancer. Relatively little scientific effort has been invested in making significant progress in the latter; therefore, developing a sound understanding of the molecular events underlying that process would be helpful. The focus of this review is to discuss the research that has been undertaken preclinically and clinically to conceptually develop the principles of, understand and target locoregional peritoneal dissemination in ovarian cancer.

Heparin-binding epidermal growth factor–like growth factor promotes transcoelomic metastasis in ovarian cancer through epithelial-mesenchymal transition

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is involved in several biological processes including cell adhesion, invasion, and angiogenesis. HB-EGF also plays a pivotal role in the progression of ovarian cancer. To investigate the significance of HB-EGF in peritoneal dissemination, we examined the roles of HB-EGF in cell adhesion, invasion, and angiogenesis in ovarian cancer. Through the suppression of focal adhesion kinase and EGF receptor activation, cell adhesive properties mediated by integrin beta(1) were diminished by the inhibition of HB-EGF expression. The reduction of HB-EGF expression attenuated the chemotactic invasive ability and the expression of matrix metalloprotease (MMP)-2 and vascular endothelial growth factor (VEGF), leading to the inhibition of cell invasion and angiogenesis. Suppression of the Snail family, which regulates the epithelial-mesenchymal transition, blocked the cell adhesion properties on extracellular matrices, the chemotactic invasive ability, and the expression of MMP9 and VEGF through the reduction of HB-EGF expression. The volume of tumor burden in the peritoneal cavity was dependent on the expression of HB-EGF. According to these results, HB-EGF contributes to cell adhesion, invasion, and angiogenesis, which are integral to transcoelomic metastasis in ovarian cancer. CRM197, an inhibitor of HB-EGF, resulted in a significant decrease of tumor burden in peritoneal dissemination, accompanied with a reduction in both cellular spreading, when assayed on an extracellular matrix, and invasive ability, when assayed in a chemotaxis chamber, as well as decreased expression of MMP9 and VEGF. Thus, HB-EGF is a mutual validating target in the peritoneal dissemination of ovarian cancer, and CRM197 may be useful as a anticancer agent for advanced ovarian cancer.

Suppression of ovarian cancer by muscle‐mediated expression of soluble VEGFR‐1/Flt‐1 using adeno‐associated virus serotype 1‐derived vector

Vascular endothelial growth factor (VEGF) is known to play a major role in angiogenesis in a variety of tumors. A soluble form of Flt-1 (sFlt-1), a VEGF receptor, is potentially useful as an antagonist of VEGF, and accumulating evidences suggest the applicability of sFlt-1 in tumor suppression by means of anti-angiogenesis. We previously demonstrated the efficacy of sflt-1 gene expression in situ to suppress tumor growth and ascites in ovarian cancer. Here, we demonstrate the therapeutic applicability of muscle-mediated expression of sFlt-1 in tumor-bearing mice. Initially, tumor suppressive action was confirmed by inoculating sFlt-1-expressing ovarian cancer (SHIN-3) cells into mice, both subcutaneously and intraperitoneally. To validate the therapeutic efficacy in a more clinically relevant model, adeno-associated virus vectors encoding sflt-1 were introduced into mouse skeletal muscles and were subsequently inoculated with tumor cells. As a result, high serum sFlt-1 levels were constantly observed, and the growth of both subcutaneously- and intraperitoneally-inoculated tumors was significantly suppressed. No delay in wound healing or adverse events of neuromuscular damage were noted, body weight did not change, and laboratory data, such as those representing liver and renal functions, were not affected. These results indicate that sFlt-1 suppresses growth and peritoneal dissemination of ovarian cancer by the inhibition of angiogenesis, and thus suggest the usefulness of gene therapy for ovarian cancer.