Sawako Minami

Binding of ovarian cancer antigen CA125/MUC16 to mesothelin mediates cell adhesion

Mesothelin is a glycosylphosphatidylinositol-linked cell surface molecule expressed in the mesothelial lining of the body cavities and in many tumor cells. Based on the finding that a soluble form of mesothelin specifically binds to ovarian carcinoma cell line OVCAR-3, we isolated cDNAs encoding a mesothelin-binding protein by expression cloning. The polypeptides encoded by the two cloned cDNA fragments matched to portions of CA125, an ovarian cancer antigen and a giant mucin-like glycoprotein present at the surface of tumor cells. By flow cytometric analysis and immunoprecipitation, we demonstrate that CA125 binds to mesothelin in a specific manner. Binding of CA125 to membrane-bound mesothelin mediates heterotypic cell adhesion as anti-mesothelin antibody blocks binding of OVCAR-3 cells expressing CA125 to an endothelial-like cell line expressing mesothelin. Finally, we show that CA125 and mesothelin are co-expressed in advanced grade ovarian adenocarcinoma. Taken together, our data indicate that mesothelin is a novel CA125-binding protein and that CA125 might contribute to the metastasis of ovarian cancer to the peritoneum by initiating cell attachment to the mesothelial epithelium via binding to mesothelin.

Immunohistochemical localization of Activin A in Human endometrial tissues during the menstrual cycle and in early pregnancy

Objective To investigate the possible localization of activin A in human endometrial tissue. Methods Human endometrial tissue was collected from 33 patients who were undergoing abdominal hysterectomy. Human decidual tissue was collected from 11 patients, who were having a therapeutic abortion. Tissue was fixed in Bouins solution and made into paraffin sections. Tissue sections were stained with monoclonal antibodies against the inhibin/activin α- and βA-subunits and activin A using an avidin-biotin-peroxidase complex technique. Results No immunostaining with antibody against the α-subunit was observed in the human endometrium during the menstrual cycle or in the decidua during early pregnancy. By contrast, immunostaining for the βA-subunit and activin. A was observed in the cytoplasm of endometrial glands at all phases of the menstrual cycle and in the decidua during early pregnancy. The intensity of immuno-staining for the βA-subunit was strong during the menstrual phase, became weaker during the early proliferative phase, and was intense again at the late proliferative phase. The immunostaining for the βA-subunit was weak during the early secretory phase and became very intense toward the midsecretory and late secretory phases. The intensity of immunostaining for activin A changed during the menstrual cycle and showed a tendency similar to that for βA-subunit. The stromal cells were weakly immunoreactive with antibodies against the βA-subunit and activin A from the menstrual to the midsecretory phase and became strong in the late secretory phase. Intense staining for the βA-subunit and activin A was observed in the cytoplasm of decidual cells during early pregnancy. Conclusion Activin A, but not inhibins, is localized in the endometrial tissue. The endometrium may be a major source of activin A during the normal menstrual cycle, and the decidua may be one of the sources of activin A during early pregnancy.

Immunohistochemical localization of inhibin/activin subunits in human placenta

Objective To examine the cellular localization of each inhibin subunit in human placenta throughout pregnancy. Method Placental tissues were collected and fixed in Bouins solution, and studied with the immunohistochemical technique avidin-biotin-peroxidase complex. Results There was immunohistochemical staining with antisera against each inhibin subunit in the syncytiotrophoblast, but not in the cytotrophoblast. In the first-trimester placenta, positive immunostaining for α-and βA-subunits was clearly observed in the syncytial layer of villi, whereas staining for βB-subunit was faint. In the second-trimester placenta, the relative intensities of staining for α-and βA-subunits were similar to those in the first-trimester placenta, and enhanced positive immunostaining with βB-subunit antiserum was observed. The relative amount of immunostainable α-subunit declined within the syncytiotrophoblast of the third-trimester placenta, whereas levels of immunostainable β-subunits were unchanged. Conclusions Inhibin subunits may be produced in the syncytiotrophoblast throughout pregnancy, and activin as well as inhibin may be synthesized in the syncytiotrophoblast of the term placenta.

Diagnostic value of preoperative SUVmax on FDG-PET/CT for the detection of ovarian cancer.

Objective The objective of this study was to investigate the preoperative diagnostic value of 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography and computed tomography (PET/CT) in patients with ovarian cancer. Methods One hundred sixty patients suspected of having malignant ovarian tumors were included in this study. All patients underwent FDG-PET/CT scans before operation, and the maximum standardized uptake value (SUVmax) of the primary tumor was measured. We evaluated the diagnostic accuracy of SUVmax for detecting malignancy and its relationship with histological findings. Results Postoperative pathological diagnoses showed that 67 were malignant, 14 were borderline malignant, and 79 were benign tumors. With the use of a cutoff SUVmax of 2.9 obtained from the receiver operating characteristic curve analysis, the sensitivity, specificity, positive predictive value, and negative predictive value for detecting malignancy were 80.6%, 94.6%, 91.5%, and 87.1%, respectively. Positive FDG accumulation (SUVmax ≥ 2.9) was shown in 89.5% of serous adenocarcinoma and in 92.3% of endometrioid adenocarcinoma. In contrast, lower frequencies of positive FDG accumulation were shown in clear cell adenocarcinoma (54.5%), mucinous adenocarcinoma (66.7%), and metastatic carcinoma (66.7%), and the median SUVmax of these 3 histological types were significantly lower than those of serous and endometrioid types. In addition, a positive FDG accumulation was shown in all patients with malignant transformation of mature cystic teratoma. Finally, of the 14 borderline malignant tumors, only 2 (14.3%) showed positive FDG accumulation. Conclusions The SUVmax on FDG-PET/CT is useful for differentiating ovarian cancer from borderline or benign tumor with a high specificity and positive predictive value. However, our data also demonstrated a lower FDG uptake value in clear cell or mucinous histological finding, suggesting that SUVmax may vary depending on the tumor histological subtype.Objective The objective of this study was to investigate the preoperative diagnostic value of 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography and computed tomography (PET/CT) in patients with ovarian cancer. Methods One hundred sixty patients suspected of having malignant ovarian tumors were included in this study. All patients underwent FDG-PET/CT scans before operation, and the maximum standardized uptake value (SUVmax) of the primary tumor was measured. We evaluated the diagnostic accuracy of SUVmax for detecting malignancy and its relationship with histological findings. Results Postoperative pathological diagnoses showed that 67 were malignant, 14 were borderline malignant, and 79 were benign tumors. With the use of a cutoff SUVmax of 2.9 obtained from the receiver operating characteristic curve analysis, the sensitivity, specificity, positive predictive value, and negative predictive value for detecting malignancy were 80.6%, 94.6%, 91.5%, and 87.1%, respectively. Positive FDG accumulation (SUVmax ≥ 2.9) was shown in 89.5% of serous adenocarcinoma and in 92.3% of endometrioid adenocarcinoma. In contrast, lower frequencies of positive FDG accumulation were shown in clear cell adenocarcinoma (54.5%), mucinous adenocarcinoma (66.7%), and metastatic carcinoma (66.7%), and the median SUVmax of these 3 histological types were significantly lower than those of serous and endometrioid types. In addition, a positive FDG accumulation was shown in all patients with malignant transformation of mature cystic teratoma. Finally, of the 14 borderline malignant tumors, only 2 (14.3%) showed positive FDG accumulation. Conclusions The SUVmax on FDG-PET/CT is useful for differentiating ovarian cancer from borderline or benign tumor with a high specificity and positive predictive value. However, our data also demonstrated a lower FDG uptake value in clear cell or mucinous histological finding, suggesting that SUVmax may vary depending on the tumor histological subtype.

Production of inhibin A and inhibin B in human ovarian sex cord stromal tumors

OBJECTIVE Our purpose was to examine the cellular localization of inhibin subunits and messenger ribonucleic acid expressions for the inhibin subunits and the serum levels of inhibin A and inhibin B in human ovarian sex cord stromal tumors. STUDY DESIGN We examined the immunohistochemical localization of the inhibin subunits and the expression of the corresponding messenger ribonucleic acids by Northern blot analysis in a granulosa cell tumor and a Sertoli-Leydig cell tumor. We also measured serum concentrations of dimeric inhibin A and inhibin B by two-site enzyme-linked immunosorbent assay. RESULTS Immunostaining specific for the inhibin alpha, betaA, and betaB subunits was observed in the granulosa cell tumor. In the Sertoli-Leydig cell tumor we observed immunostaining specific for the alpha subunit in Leydig tumor cells and that specific for the betaA subunit in Sertoli tumor cells and that specific for the betaB subunit in both tumor cells. Northern blot analysis revealed the presence of messenger ribonucleic acids for the alpha, betaA, and betaB subunits in the granulosa cell tumor and the Sertoli-Leydig cell tumor. The serum levels of dimeric inhibin A and inhibin B in patients were elevated preoperatively and decreased progressively after surgery. CONCLUSION Our results suggest that inhibin A and inhibin B are produced by the human sex cord stromal tumors and that inhibins might be the useful markers of the tumors.

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.

Immunohistochemical localization of inhibin and activin subunits in human epithelial ovarian tumors

OBJECTIVE Our purpose was to examine the cellular localization of inhibin and activin subunits in human epithelial ovarian tumors. STUDY DESIGN We examined the immunohistochemical localization of the alpha, betaA, and betaB subunits of inhibin in human mucinous and serous ovarian tumors including adenoma, cystic tumor with borderline malignancy, and adenocarcinoma. RESULTS Immunostaining specific for the alpha, betaA, and betaB subunits of inhibin was observed in the tumor cells of the mucinous adenoma and the cystic tumor with borderline malignancy. We observed negative immunostaining specific for the alpha subunit and positive staining specific for the betaA and betaB subunits in the tumor cells of the mucinous adenocarcinoma. We did not observe any staining for the alpha subunit of inhibin in the serous tumors including benign adenoma, cystic tumor with borderline malignancy, and adenocarcinoma. However, positive staining results for the betaA and betaB subunits were observed in the serous tumor cells. CONCLUSION Our results suggest that inhibins and activins might be secreted by the mucinous adenoma and the cystic tumor with borderline malignancy and that activins might be secreted by the mucinous adenocarcinoma and the serous tumors including benign adenoma, cystic tumor with borderline malignancy, and adenocarcinoma.

Role of the renin-angiotensin system in gynecologic cancers.

Recent studies have shown an activation of the local renin-angiotensin system (RAS) in various tumor tissues, including the abundant generation of angiotensin II (Ang II) by angiotensin-converting enzyme (ACE) and the upregulation of angiotensin II type 1 receptor (AT1R) expression. Thus, considerable attention has been paid not only to the role of the RAS in cancer progression, but also to the blockade of RAS as a new approach to the treatment of human cancer. There is increasing evidence that the Ang II-AT1R pathway is involved in tumor growth, angiogenesis and metastasis in various experimental animal models, suggesting the therapeutic potential of an ACE inhibitor and AT1R blocker. In addition, specific Ang II-degrading enzymes are also expressed in tumors and play a regulatory role in tumor cell proliferation and invasion. This review focuses on the role of the RAS in the progression of gynecologic cancers, such as cervical cancer, endometrial cancer, ovarian cancer, and gestational choriocarcinoma. We present here the clinical potential of blocking the RAS as a novel and promising strategy for the treatment of gynecologic cancers.

Downregulation of indoleamine 2, 3-dioxygenase expression in the villous stromal endothelial cells of placentas with preeclampsia

INTRODUCTION Previous studies have shown that indoleamine 2, 3-dioxygenase (IDO), an immunosuppressive enzyme that converts tryptophan to kynurenine, is expressed in the placenta and might play a role in the maintenance of pregnancy, although its associations with the pathogeneses of preeclampsia (PE) and fetal growth restriction (FGR) remain unclear. The objective of this study was to investigate the differences in IDO expression among normal, PE, and FGR placentas, and the associations between IDO expression and clinical symptoms, or the expression of fms-like tyrosine kinase receptor-1 (Flt-1). METHODS Immunohistochemical studies of IDO and Flt-1 expression were performed in human placentas that were complicated with FGR alone (n=19), PE alone (n=20), or both PE and FGR (n=39), and gestational age-matched controls (n=23). RESULTS It was found that IDO was expressed on endothelial cells in the villous stroma, while Flt-1 was located on trophoblast cells. The IDO expression level of the PE alone group was significantly lower than those of the FGR alone and control groups. The IDO expression of the PE+FGR group was significantly lower than that of the FGR alone group. Lower IDO expression was significantly correlated with more severe maternal hypertension or proteinuria in PE patients, who exhibited higher Flt-1 expression. The late onset PE patients exhibited significantly lower IDO expression than the early onset PE patients. CONCLUSION This study demonstrated that the downregulation of IDO expression on the endothelial cells of the villous stroma was associated with PE, but not FGR, suggesting that IDO might be involved in the pathophysiology of PE.

AG490, a Jak2 inhibitor, suppressed the progression of murine ovarian cancer.

Ovarian cancer is the major cause of cancer death among female genital malignancies, and requires developing novel therapeutic measures. Immune escape and acquisition of tolerance by tumor cells are essential for cancer growth and progression. An immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) overexpression in tumors is essential for host immune tolerance. Janus-activated kinase-signal transducer and activator of transcription (JAK-STAT) pathway is involved in various kinds of tumor biology. Thus, we examined the effects of STAT1 inhibition by AG490 (a JAK2 inhibitor) on ovarian cancer progression in mice. In vitro study, IFN-γ treatment up-regulated Ido mRNA expression with STAT1 activation in OV2944-HM-1 cells, whereas AG490 treatment significantly inhibited this effect with the suppression of STAT1 phosphorylation. In vivo model, OV2944-HM-1 cells were intraperitoneally/subcutaneously transplanted into syngeneic immunocompetent female mice. AG490 treatment significantly suppressed subcutaneous tumor growth, compared with control. Consistently, in mice intraperitoneally inoculated HM-1 cells, the same treatment significantly improved survival rate with the reduced number of intraperitoneal tumors. Actually, intratumoral IDO expression was significantly suppressed with the reduction of STAT1 activation in AG490-treated mice. Moreover, in tumor microenvironment of mice treated with AG490, the accumulation of anti-tumor leukocytes such as CD8(+) T-cells, M1 macrophages, and NK cells was apparently exaggerated with the reciprocal reduction of regulatory T cells. Furthermore, intratumoral expression of anti-tumor cytokines such as IL-1α, IL-1β and IL-12 expression was significantly enhanced in mice treated with AG490. Collectively, JAK/STAT signal pathways may be good molecular target for immunotherapy of ovarian cancer.