Kaoru Niimi

Akt–Girdin Signaling in Cancer-Associated Fibroblasts Contributes to Tumor Progression

PI3K-Akt signaling is critical for the development, progression, and metastasis of malignant tumors, but its role in the tumor microenvironment has been relatively little studied. Here, we report that the Akt substrate Girdin, an actin-binding protein that regulates cell migration, is expressed and activated by Akt phosphorylation in cancer-associated fibroblasts (CAF) and blood vessels within the tumor microenvironment. Lewis lung tumors grafted into mice defective in Akt-mediated Girdin phosphorylation (SA transgenic mice) exhibited a decrease in both CAF infiltration and tumor growth, compared with wild-type (WT) host control animals. Contrasting with the findings of other studies, we found that Akt-dependent phosphorylation of Girdin was not a rate-limiting step in the growth of endothelial cells. In addition, Lewis lung tumors displayed limited outgrowth when cotransplanted with CAF derived from tumor-bearing SA transgenic mice, compared with CAF derived from tumor-bearing WT mice. Collectively, our results revealed a role for Akt-mediated Girdin phosphorylation in CAF during tumor progression, highlighting the need to inhibit Akt function in both tumor cells and cells that comprise the tumor microenvironment.

Expression of chromobox homolog 7 (CBX7) is associated with poor prognosis in ovarian clear cell adenocarcinoma via TRAIL-induced apoptotic pathway regulation

Ovarian cancer is the most lethal gynecologic malignancy, and clear cell adenocarcinoma of the ovary (OCCA), in particular, has a relatively poor prognosis among the ovarian cancer subtypes because of its high chemoresistance. Chromobox (CBX) 7 is a polycomb repressive complex 1 component that prolongs the lifespan of normal human cells by downregulating the INK4a/ARF expression which promotes cell‐cycle progression. However, recent reports studying the relationship between CBX7 expression and patient survival have differed regarding the tumor cell origins, and the precise role of CBX7 in human carcinomas remains obscure. In this study, we analyzed CBX7 expression by immunohistochemistry in 81 OCCA patients and evaluated its association with their clinical outcomes. Both the overall and progression‐free survival rates of the CBX7‐positive patients were significantly shorter than those of the CBX7‐negative patients (p < 0.05). CBX7 knockdown experiments using two OCCA cell lines, TOV21G and KOC‐7C, revealed that cell viability was significantly reduced compared to the control cells (p < 0.001). Expression microarray analysis revealed that apoptosis‐related genes, particularly tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL), were significantly upregulated in CBX7 knockdown cells (p < 0.01). We further confirmed that CBX7 knockdown resulted in TRAIL‐induced apoptosis in the OCCA cells. Thus, in this study, we showed for the first time that CBX7 was associated with a decreased OCCA prognosis. We also successfully demonstrated that the TRAIL pathway is a novel target for CBX7 expression modulation in these cells, and therapeutic agents utilizing the TRAIL pathway may be particularly effective for targeted OCCA therapy.

The REV7 Subunit of DNA Polymerase ζ Is Essential for Primordial Germ Cell Maintenance in the Mouse

Background: Biological significance of REV7 in mouse development has not been elucidated. Results: REV7-deficient mice show germ cell aplasia at birth in both sexes, and primordial germ cells (PGCs) were lost because of apoptosis during migration at an early embryonic stage. Conclusion: REV7 is essential for PGC maintenance in the mouse. Significance: REV7 is a novel regulator of PGC survival. REV7 (also known as MAD2L2 and MAD2B) is involved in DNA repair, cell cycle regulation, gene expression, and carcinogenesis. In vitro studies show that REV7 interacts with several proteins and regulates their function. It has been reported that human REV7 is highly expressed in the adult testis by Northern blot analysis. However, the significance of REV7 in mammalian development has not been elucidated. Here, we present analyses of REV7-deficient (Rev7−/−) mice to clarify the significance of Rev7 in mouse development. In WT mice (Rev7+/+), Rev7 expression was ubiquitously observed in the embryo and confined to germ cells in the testes after birth. Rev7−/− mice exhibited growth retardation and a partial embryonic lethal phenotype. Mice that survived to adulthood were infertile in both sexes and showed germ cell aplasia in the testes and ovaries. Analyses of Rev7−/− embryos revealed that primordial germ cells (PGCs) were present at embryonic day 8.5 (E8.5). However, progressive loss of PGCs was observed during migration, and PGCs were absent in the genital ridges at E13.5. An increase of apoptotic cells was detected not only among PGCs but also in the forebrain of the Rev7−/− embryo, whereas cell proliferation was unaffected. Moreover, DNA damage accumulation and increased levels of histone methylation were detected in Rev7−/− embryos, and expression of Oct4 and Nanog was deregulated by REV7 deficiency at E8.5. These findings indicate that Rev7 is essential for PGC maintenance by prevention of apoptotic cell death in the mouse.

Suppression of REV7 enhances cisplatin sensitivity in ovarian clear cell carcinoma cells

Human REV7 (also known as MAD2L2 and MAD2B) is involved in DNA repair, cell cycle regulation, gene transcription, and carcinogenesis. In this study, we evaluated the expression of REV7 in epithelial ovarian cancer (EOC) and analyzed the association between its expression and chemosensitivity in ovarian clear cell carcinoma (CCC) cells. Expression of REV7 in human EOC tissues was assessed by immunohistochemical staining. Expression was detected in the majority of EOCs (92.0%) with especially high levels of expression frequently observed in CCCs (73.5%) compared with that of non‐CCCs (53.4%). Enhanced immunoreactivity to REV7 was associated with poor prognosis represented by reduced progression‐free survival in advanced stage (stage II–IV) EOC as assessed using Kaplan–Meier curves and log–rank tests. The effects of REV7 knockdown on cell proliferation and chemosensitivity in CCC cells were also analyzed in vitro and in vivo. Knockdown of REV7 in CCC cells decreased cell proliferation without affecting cell cycle distribution. Additionally, the number of apoptotic cells and DNA damaged cells were increased after cisplatin treatment. In a nude mouse tumor xenograft model, inoculated REV7‐knockdown tumors showed significantly reduced tumor volumes after cisplatin treatment compared with those of the control group. These findings indicate that depletion of REV7 enhances sensitivity to cisplatin treatment in CCC, suggesting that REV7 is a candidate molecular target in CCC management.

Identification of causative pregnancy of gestational trophoblastic neoplasia diagnosed during pregnancy by short tandem repeat analysis.

Highlights • Gestational trophoblastic neoplasia can arise during the first trimester originating from trophoblasts of concurrent pregnancy.• Intraplacental choriocarcinoma can be developed from trophoblasts of a previous pregnancy.

A combination of circulating miRNAs for the early detection of ovarian cancer

Ovarian cancer is the leading cause of gynecologic cancer mortality, due to the difficulty of early detection. Current screening methods lack sufficient accuracy, and it is still challenging to propose a new early detection method that improves patient outcomes with less-invasiveness. Although many studies have suggested the utility of circulating microRNAs in cancer detection, their potential for early detection remains elusive. Here, we develop novel predictive models using a combination of 8 circulating serum miRNAs. This method was able to successfully distinguish ovarian cancer patients from healthy controls (area under the curve, 0.97; sensitivity, 0.92; and specificity, 0.91) and early-stage ovarian cancer from patients with benign tumors (0.91, 0.86 and 0.83, respectively). This method also enables subtype classification in 4 types of epithelial ovarian cancer. Furthermore, it is found that most of the 8 miRNAs were packaged in extracellular vesicles, including exosomes, derived from ovarian cancer cells, and they were circulating in murine blood stream. The circulating miRNAs described in this study may serve as biomarkers for ovarian cancer patients. Early detection and subtype determination prior to surgery are crucial for clinicians to design an effective treatment strategy for each patient, as is the goal of precision medicine.

Survival benefit of taxane plus platinum in recurrent ovarian cancer with non-clear cell, non-mucinous histology

Objective This study was conducted to examine the effects of front-line chemotherapy on overall survival (OS) and postrecurrence survival (PRS) of patients with recurrent ovarian cancer, when stratifying the histologic type. Methods Five hundred and seventy-four patients with recurrent ovarian cancer with sufficient clinical information, including front-line chemotherapy, were analyzed. The pathologic slides were evaluated by central pathologic review. The patients were divided into two groups: group A (n=261), who underwent taxane plus platinum, and group B (n=313), who underwent conventional platinum-based chemotherapy without taxanes. Results The median age was 54 years (range, 14 to 89 years). Group A had significantly better median OS (45.0 months vs. 30.3 months, p<0.001) and PRS (23.0 months vs. 13.0 months, p<0.001) compared to group B. The OS and PRS were similar between the groups in patients with clear cell or mucinous histology. In contrast, among patients with non-clear cell, non-mucinous histologies, the OS and PRS of group A were significantly better than those of group B (OS, p<0.001; PRS, p<0.001). Multivariable analyses revealed that, among patients with non-clear cell, non-mucinous histologies, chemotherapy including taxane and platinum was an independent predictor of favorable survival outcomes. Conversely, in patients with clear cell or mucinous histology, taxane-including platinum-based combination chemotherapy did not improve the OS and PRS compared to a conventional platinum-based regimen which did not include taxanes. Conclusion Since the emergence of taxane plus platinum, the prognosis of patients with recurrent ovarian cancer has improved. However, we here demonstrate that this improvement is limited to patients with non-clear cell, non-mucinous histologies.

Feasibility and benefit of concurrent chemoradiotherapy for elderly patients with uterine cervical cancer.

Background Elderly patients with uterine cervical cancer reportedly have a poorer prognosis than younger patients. Until now, the benefit of concurrent chemoradiotherapy (CCRT) for elderly patients has been considered limited. Methods We retrospectively analyzed 49 women with cervical cancer aged >70 years primarily treated with radiotherapy (RT) or CCRT in our institute between 2003 and 2014. Treatment compliance, toxicity, and survival benefit were analyzed. Results A total of 49 patients were identified in this retrospective analysis. Twenty patients with a median age of 75.4 years (range 70–77) were treated with CCRT and 29 patients with a median age of 77.9 years (range 70–89) underwent RT. In the CCRT group, 14 patients (70%) completed CCRT consisting of radiotherapy and 5 courses of cisplatin plus 5-fluorouracil including patients requiring a dose reduction of chemotherapy. The median overall survival (OS) in the CCRT and RT groups was 66.9 and 60.1 months, respectively (p = 0.156). The most common grade 3/4 acute toxicity was hyponatremia (35.0%), followed by neutropenia (15.0%) and diarrhea (10.0%) in the CCRT group, while this was anemia (17.2%) followed by radiation enteritis (10.3%) in the RT group. Conclusions CCRT was well tolerated in elderly patients with cervical cancer. Careful attention should be paid to the different characteristics of treatment-related toxicities in this group compared with younger patients.

PRIMA-1MET induces apoptosis through accumulation of intracellular reactive oxygen species irrespective of p53 status and chemo-sensitivity in epithelial ovarian cancer cells

There is an intensive need for the development of novel drugs for the treatment of epithelial ovarian cancer (EOC), the most lethal gynecologic malignancy due to the high recurrence rate. TP53 mutation is a common event in EOC, particularly in high-grade serous ovarian cancer, where it occurs in more than 90% of cases. Recently, PRIMA-1 and PRIMA-1MET (p53 reactivation and induction of massive apoptosis and its methylated form) were shown to have an antitumor effect on several types of cancer. Despite that PRIMA-1MET is the first compound evaluated in clinical trials, the antitumor effects of PRIMA-1MET on EOC remain unclear. In this study, we investigated the therapeutic potential of PRIMA-1MET for the treatment of EOC cells. PRIMA-1MET treatment of EOC cell lines (n=13) resulted in rapid apoptosis at various concentrations (24 h IC50 2.6–20.1 µM). The apoptotic response was independent of the p53 status and chemo-sensitivity. PRIMA-1MET treatment increased intracellular reactive oxygen species (ROS), and PRIMA-1MET-induced apoptosis was rescued by an ROS scavenger. Furthermore, RNA expression analysis revealed that the mechanism of action of PRIMA-1MET may be due to inhibition of antioxidant enzymes, such as Prx3 and GPx-1. In conclusion, our results suggest that PRIMA-1MET represents a novel therapeutic strategy for the treatment of ovarian cancer irrespective of p53 status and chemo-sensitivity.

Oncologic outcome after recurrence in patients with stage I epithelial ovarian cancer: are clear-cell and mucinous histological types a different entities?

OBJECTIVES This study was conducted to estimate the oncologic outcome of stage I epithelial ovarian carcinoma (EOC) patients after recurrence. STUDY DESIGN After central pathological review and searching of the medical records of multi-institutions, a total of 103 relapsed patients with stage I EOC were analyzed. The major endpoint was postrecurrence survival (PRS). RESULTS The median follow-up for surviving patients was 57.5 (5.7-242.0) months. The median age was 52 (14-89). Among the patients, 19 (18.4%) had FIGO IA disease, and 4 (3.9%) and 80 (77.7%) had IB and IC disease, respectively. Regarding the histological type, the clear-cell type was the most frequently observed (N=42: 40.8%). The 3/5-year overall and PRS rates of all patients were 63.7/47.9 and 38.2/24.0%, respectively. The 5-year PRS rates of patients with serous, endometrioid, clear-cell, and mucinous tumors were 44.9, 35.0, 19.8, and 0%, respectively. On stratifying by the histological type, the overall and postrecurrence survival rates of patients with the mucinous/clear-cell types were significantly poorer than in those with the non-mucinous/clear-cell types (OS: P=0.0253, PRS: P=0.0016). In multivariate analyses, the FIGO stage (IA/IB vs. IC) and histological type (clear-cell/mucinous vs. non- clear-cell/mucinous) retained their significance as prognostic factors of a poorer PRS {stage IC (vs. IA/B) HR 2.176 (95% CI: 1.059-4.470), P=0.0343: clear-cell/mucinous (vs. non- clear-cell/mucinous): HR: 2.486(95% CI: 1.416-4.364), P=0.0015). CONCLUSIONS Even if at stage I, once patients with a mucinous/clear-cell histology experience recurrence, subsequent survival is extremely poor.