Kiyosumi Shibata

ALX1 induces Snail expression to promote epithelial to mesenchymal transition and invasion of ovarian cancer cells

Ovarian cancer is a highly invasive and metastatic disease with a poor prognosis if diagnosed at an advanced stage, which is often the case. Recent studies argue that ovarian cancer cells that have undergone epithelial-to-mesenchymal transition (EMT) acquire aggressive malignant properties, but the relevant molecular mechanisms in this setting are not well-understood. Here, we report findings from an siRNA screen that identified the homeobox transcription factor ALX1 as a novel regulator of EMT. RNA interference-mediated attenuation of ALX1 expression restored E-cadherin expression and cell-cell junction formation in ovarian cancer cells, suppressing cell invasion, anchorage-independent growth, and tumor formation. Conversely, enforced expression of ALX1 in ovarian cancer cells or nontumorigenic epithelial cells induced EMT. We found that ALX1 upregulated expression of the key EMT regulator Snail (SNAI1) and that it mediated EMT activation and cell invasion by ALX1. Our results define the ALX1/Snail axis as a novel EMT pathway that mediates cancer invasion.

Is there any association between retroperitoneal lymphadenectomy and survival benefit in ovarian clear cell carcinoma patients

BACKGROUNDnTo estimate the survival impact of systemic retroperitoneal lymphadenectomy in patients diagnosed with International Federation of Gynecology and Obstetrics pTI-IIb clear cell carcinoma of the ovary (CCC).nnnPATIENTS AND METHODSnDemographic and clinicopathologic data were obtained from the Tokai Ovarian Tumor Study Group between 1986 and 2006. Survival curves were calculated using the Kaplan-Meier method. Differences in survival rates were analyzed using the log-rank test.nnnRESULTSnA total of 205 patients had clinical pTI-IIb CCC (median age: 52 years, range: 30-75). One hundred and four (50.7%) patients underwent systemic retroperitoneal lymphadenectomy. Lymphadenectomy was not associated with improved disease-free and overall survival in all patients (P = 0.353 and P = 0.645, respectively). Moreover, lymphadenectomy did not improve the overall survival in those with pTIc CCC (P = 0.433). Similarly, on univariate analysis, age, volume of ascites, preoperative CA 125 values, and regimen of chemotherapy were not significant factors. In addition, there was no significant difference in the ratio of positive lymph node metastases regardless of the completion of lymphadenectomy (P = 0.955).nnnCONCLUSIONnOur data suggest that patients with pTI-IIb CCC who underwent lymphadenectomy did not show a significant improvement in survival. There was no significant difference in the overall and disease-free survival rates in pTI-IIb CCC patients regardless of the completion of surgical staging lymphadenectomy.

Significant clinical response of progressive recurrent ovarian clear cell carcinoma to glypican-3-derived peptide vaccine therapy: two case reports.

Carcinoembryonic antigen glypican-3 (GPC3) is expressed by >40% of ovarian clear cell carcinoma (CCC) and is a promising immunotherapeutic target. We previously reported the safety of and immunological and clinical responses to a GPC3-derived peptide vaccine in a phase I clinical trial of patients with advanced hepatocellular carcinoma (HCC). Although the efficacy of the GPC3-derived peptide vaccine against HCC patients was evaluated, other GPC3-positive cancer patients have not yet been investigated. Therefore, we conducted a phase II trial to evaluate the clinical outcome of ovarian CCC patients treated with a GPC3-derived peptide vaccine. The GPC3 peptide was administered at a dose of 3 mg per body. Patients received an intradermal injection of the GPC3 peptide emulsified with incomplete Freund’s adjuvant. Vaccinations were performed biweekly from the first until the 6th injection and were then repeated at 6-week intervals after the 7th injection. Treatment continued until disease progression. We herein present two patients with chemotherapy-refractory ovarian CCC who achieved a significant clinical response in an ongoing trial of a GPC3 peptide vaccine. Case 1, a 42-year-old patient with advanced recurrent ovarian CCC with liver and retroperitoneal lymph node metastases, received the HLA-A24-restricted GPC3 peptide vaccine. Contrast-enhanced CT at week 10 revealed a partial response (PR) using RECIST criteria. Case 2 was a 67-year-old female with multiple lymph node metastases. She was injected with the HLA-A2-restricted GPC3 peptide vaccine. According to RECIST, PR was achieved at week 37. The stabilization of their diseases over one year provided us with the first clinical evidence to demonstrate that GPC3 peptide-based immunotherapy may significantly prolong the overall survival of patients with refractory ovarian CCC.

Glypican‐3 could be an effective target for immunotherapy combined with chemotherapy against ovarian clear cell carcinoma

Glypican‐3 (GPC3) is useful not only as a novel tumor marker, but also as an oncofetal antigen for immunotherapy. We recently established HLA‐A2‐restricted GPC3144‐152 peptide‐specific CTL clones from hepatocellular carcinoma patients after GPC3144‐152 peptide vaccination. The present study was designed to evaluate the tumor reactivity of a HLA‐A2‐restricted GPC3144‐152 peptide‐specific CTL clone against ovarian clear cell carcinoma (CCC) cell lines. The GPC3144‐152 peptide‐specific CTL clone could recognize HLA‐A2‐positive and GPC3‐positive ovarian CCC cell lines on interferon (IFN)‐γ enzyme‐linked immunospot assay and showed cytotoxicity against KOC‐7c cells. The CTL clone recognized naturally processed GPC3‐derived peptide on ovarian CCC cells in a HLA class I‐restricted manner. Moreover, we confirmed that the level of GPC3 expression was responsible for CTL recognition and that subtoxic‐dose chemotherapy made tumor cells more susceptible to the cytotoxic effect of CTL. Thus, it might be possible to treat ovarian CCC patients by combining chemotherapy with immunotherapy. Our data suggest that GPC3 could be an effective target for immunotherapy against ovarian CCC. (Cancer Sci 2011; 102: 1622–1629)

Identification and characterization of cancer stem cells in ovarian yolk sac tumors.

Recent evidence supports the cancer stem cell theory, that is, that malignant tumors arise from cells termed cancer stem cells or tumor‐initiating cells that have the ability to self‐renew and are responsible for maintaining the tumor. Cells with marked tumor‐initiating capacity have recently been identified in a number of solid tumors. CD133 (PROM1, human prominin‐1) has been used as a marker to detect stem cells (progenitor cells) and cancer stem cells (tumor‐initiating cells) in various tissues. Ovarian yolk sac tumors (YSTs) are rare and highly malignant. The present study was designed to evaluate the tumor‐forming ability of CD133+ cells in ovarian YST cell lines and to examine the characteristics of CD133+ cells, such as cell growth and invasiveness. Our data suggest ovarian YST to be maintained by a rare fraction of cancer stem‐like cells that express the cell surface marker CD133. (Cancer Sci 2010)

Efficacy of glypican-3-derived peptide vaccine therapy on the survival of patients with refractory ovarian clear cell carcinoma

ABSTRACT Compared with other epithelial ovarian carcinoma subtypes, ovarian clear cell carcinoma (OCCC) has been recognized to show chemoresistance. Therefore, new treatment modalities are required for patients with OCCC that is refractory to chemotherapy. The carcinoembryonic antigen glypican-3 (GPC3) is expressed by approximately half of OCCC and is a promising immunotherapeutic target. The purpose of this study was to evaluate the effect of GPC3 peptide vaccine against refractory OCCC patients. We conducted a phase II trial with a GPC3-derived peptide vaccine in OCCC patients. Immunological responses were analyzed by ex vivo IFNγ ELISPOT assay. We also evaluated control subjects, who received best supportive care without vaccinations during the same period. Thirty-two patients with refractory OCCC were enrolled between July 2010 and September 2015, and underwent GPC3 peptide vaccination. Fifteen patients were vaccinated less than six times because their general condition progressively deteriorated, and 17 patients were vaccinated at least six times. Three patients showed a partial response as the best overall response. The GPC3 peptide vaccine induced a GPC3-specific CTL response in 15 out of 24 patients who had PBMCs collected three times or more. The prognosis of palliative care patients without GPC3 peptide vaccinations was significantly poorer than that of those with GPC3 peptide vaccinations (post cancer-treatment survival: p = 0.002). Although the disease control rate was not high, our results suggest that GPC3 peptide vaccinations may hold a significant impact to prolong survival of patients with refractory OCCC, allowing them to maintain quality of life with no serious toxicities.

Functional interaction between peritoneal mesothelial cells and stem cells of ovarian yolk sac tumor (SC-OYST) in peritoneal dissemination

OBJECTIVEnIn recent years it has been indicated that ecological niches play important roles in the maintenance of cancer stem cells (CSCs). We investigated interactions between peritoneal mesothelial cells and SC-OYST based on the hypothesis that peritoneal mesothelial cells have the potential to provide one of the niches for SC-OYST.nnnMETHODSnWe divided NOY1 cells into CD133-positive and -negative cells. Using the co-culture of NOY1 and peritoneal mesothelial cells, we compared the expression of CD133, colony formation, and the capacity for migration and invasion. In addition, we assessed the inhibitory effects of AMD3100, a neutralizing antibody against a chemokine receptor (CXCR4). Then, we examined whether AMD3100 affects the tumorigenicity of NOY1-CD133+ cells in vivo.nnnRESULTSnWhen NOY1 cells were co-cultured with peritoneal mesothelial cells, we observed the high-level expression of CD133. The number of colonies of NOY1-CD133+ cells was 2.4 times that of NOY1-CD133- cells. In contrast, on co-culture with peritoneal mesothelial cells, it was 4.3 times. When NOY1 cells were cultivated in the upper layer and peritoneal mesothelial cells were cultivated in the lower chamber, NOY1-CD133+ cells showed a greater capacity for migration and invasion than NOY1-CD133- cells. By adding AMD3100 to the co-culture systems, the colony formation, migration, and invasion of NOY1-CD133+ cells were inhibited. In addition, AMD3100 inhibited the tumorigenicity of NOY1-CD133+ cells in vivo.nnnCONCLUSIONSnOur data suggest that peritoneal mesothelial cells have the potential to provide one of the niches for NOY1 cells. Investigation of the niches of SC-OYST will help elucidate important targets for therapeutic approaches.

Clinicopathologic features of epithelial ovarian carcinoma in younger vs. older patients: analysis in Japanese women

Objective The purpose of this study was to clarify the clinical features of epithelial ovarian carcinoma (EOC) in younger vs. older patients in Japan. Methods We collected data on 1,562 patients with EOC treated at multiple institutions in the Tokai Ovarian Tumor Study Group, and analyzed them retrospectively. All patients were divided into 2 groups: group A (≤40 years old) and group B (>40 years old). The data were analyzed to evaluate prognostic factors and the distribution of features in each group. Patients were subjected to univariate and multivariate analyses to evaluate overall survival (OS). Results The median follow-up time was 45.1 months (range, 1 to 257 months). Patients in group A had a significantly higher rate of stage I disease (67.3% vs. 42.6%, respectively; p<0.001) and the mucinous type (36.7% vs. 13.5%, respectively; p<0.001) than those in group B. There was a significant difference of OS between the 2 groups (p=0.013). However, upon stratification according to the stage, there were no significant differences in the OS between the 2 groups (group A vs. B: stage I, p=0.533; stage II-IV, p=0.407). Multivariate analysis revealed that younger age was not an independent prognostic factor for OS. Conclusion On the basis of our data, younger patients had a different clinical profile than older patients, particularly regarding the stage of the disease and pathological distribution; however, they showed a similar long-term prognosis, even upon stratification according to the stage.

Possible association between stem-like hallmark and radioresistance in human cervical carcinoma cells

We aimed to investigate the possibility of an association between a stem‐like hallmark and radiotherapeutic sensitivity in human cervical carcinoma cells.

PLAGL2 regulates actin cytoskeletal architecture and cell migration.

Pleomorphic adenoma gene like-2 (PLAGL2), a member of the PLAG gene family, is a C2H2 zinc finger transcriptional factor that is involved in cellular transformation and apoptosis. In this report, we show that PLAGL2 is associated with the organization of stress fibers and with small guanosine triphosphatase (GTPase) activity. Depletion of PLAGL2 in two different ovarian cancer cell lines, ES-2 and HEY, induced activation of RhoA, whereas activity of Rac1 was suppressed. Organization of actin stress fibers and focal adhesions was significantly promoted by PLAGL2 knockdown in a RhoA-dependent manner. Conversely, exogenous expression of PLAGL2 in MDA-MB-231 cells, a breast cancer cell line, resulted in the activation of Rac1 and the inactivation of RhoA. In addition, PLAGL2 expression induced lamellipodia formation and disruption of stress fiber formation. Finally, we show that CHN1 expression is essential for Rac1 inactivation in PLAGL2-depleted cells. Our results demonstrate a crucial role of PLAGL2 in actin dynamics and give further insight into the role of PLAGL2 in cellular transformation and apoptosis.