Hiroaki Kajiyama

Selective killing of ovarian cancer cells through induction of apoptosis by nonequilibrium atmospheric pressure plasma

Two independent ovarian cancer cell lines and fibroblast controls were treated with nonequilibrium atmospheric pressure plasma (NEAPP). Most ovarian cancer cells were detached from the culture dish by continuous plasma treatment to a single spot on the dish. Next, the plasma source was applied over the whole dish using a robot arm. In vitro cell proliferation assays showed that plasma treatments significantly decreased proliferation rates of ovarian cancer cells compared to fibroblast cells. Flow cytometry and western blot analysis showed that plasma treatment of ovarian cancer cells induced apoptosis. NEAPP could be a promising tool for therapy for ovarian cancers.

Functional Expression of the Angiotensin II type 1 receptor in human ovarian carcinoma cells and its blockade therapy resulting in suppression of tumor invasion, angiogenesis, and peritoneal dissemination

Purpose: Angiotensin II is a bioactive peptide of the renin-angiotensin system, acting not only as a vasoconstrictor but also as a growth promoter via angiotensin II type 1 receptors (AT1R). The present study examined AT1R expression in human ovarian carcinoma and attempted to determine whether AT1R blocker could suppress the tumor progression. Experimental Design: Expression of AT1R, vascular endothelial growth factor (VEGF), and CD34 was immunohistochemically analyzed in ovarian tumor tissues (n = 99). Effects of AT1R blocker on invasive potential and VEGF secretion in ovarian cancer cells were examined in vitro. Effects of AT1R blocker in vivo were evaluated in a mouse model of peritoneal carcinomatosis. Results: AT1R was expressed in 57 of 67 (85%) invasive ovarian adenocarcinomas and 12 of 18 (66%) borderline malignant tumors but in only 2 of 14 (14%) benign cystadenomas. In invasive carcinomas, VEGF expression intensity and intratumor microvessel density were significantly higher in cases that were strongly positive for AT1R (n = 37) compared with those in cases weakly positive (n = 20) or negative (n = 10) for AT1R. Angiotensin II significantly enhanced the invasive potential and VEGF secretion in AT1R-positive SKOV-3 ovarian cancer cells, both of which were completely inhibited by the AT1R blocker candesartan. Administration of candesartan into SKOV-3-transplanted athymic mice resulted in the reduction of peritoneal dissemination, decreased ascitic VEGF concentration, and suppression of tumor angiogenesis. Conclusions: AT1R is functionally expressed in ovarian carcinoma and involved in tumor progression and angiogenesis. AT1R blockade therapy may become a novel and promising strategy for ovarian cancer treatment.

Involvement of SDF‐1α/CXCR4 axis in the enhanced peritoneal metastasis of epithelial ovarian carcinoma

Epithelial ovarian carcinoma (EOC) spreads by implantation of tumor cells onto the human peritoneal mesothelial cells (HPMCs) lining the peritoneal cavity. The aim of this study was to determine whether the stromal cell‐derived factor‐1α (SDF‐1α)/CXCR4 axis is involved in the interaction of EOC cells with HPMCs in peritoneal metastasis. Clinically, we first evaluated CXCR4 expression in sections from 36 primary EOCs using immunohistochemistry. We next examined whether SDF‐1α played roles in EOC progression, including in proliferation, cell motility, attachment to HPMCs, and the in vivo development of peritoneal metastasis through CXCR4. Of the 36 carcinomas, 16 cases (44.4%) were positive for CXCR4 immunoexpression. Positive CXCR4 expression significantly predicted poorer overall survival compared with negative expression (p = 0.0069). We found CXCR4 expression in both EOC cells and HPMCs. In contrast, the level of production of SDF‐1α by HPMCs was higher than that by various EOC cells. Functionally, SDF‐1α induced enhanced attachment between ES‐2 cells and HPMCs or extracellular matrix components. The enhancement of adhesion potential by SDF‐1α was inhibited by AMD3100, a CXCR4 antagonist, and by phosphatidylinositol 3 kinase and p44/42 inhibitors. Furthermore, intraperitoneal treatment with AMD3100 resulted in reduced dissemination in nude mice inoculated with ES‐2 cells. The present results suggest that there may be a link between the SDF‐1α/CXCR4 axis and enhanced intraperitoneal dissemination of EOC and that CXCR4 may be a novel target for the treatment of EOC.

Indoleamine 2,3-dioxygenase is a novel prognostic indicator for endometrial cancer

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-catabolising enzyme inducing immune tolerance. The present study aimed to investigate IDO expression and its prognostic significance in endometrial cancer. Indoleamine 2,3-dioxygenase expression in endometrial cancer tissues (n=80) was immunohistochemically scored as four groups (IDO−, 1+, 2+, and 3+). The high IDO expression (IDO2+ or 3+) in tumour cells was found in 37 (46.3%) of the 80 cases, and was positively correlated with surgical stage, myometrial invasion, lymph-vascular space involvement, and lymph node metastasis, but not with the histological grade. Patients with high IDO expression had significantly impaired overall survival and progression-free survival (PFS) (P=0.002 and P=0.001, respectively) compared to patients with no or weak expression of IDO (IDO− or 1+). The 5-year PFS for IDO−/1+, 2+, and 3+ were 97.7, 72.9, and 36.4%, respectively. Even in patients with early-stage disease (International Federation of Gynecology and Obstetrics I/II, n=64), the PFS for IDO2+/3+ was significantly poor (P=0.001) compared to that for IDO−/1+. On multivariate analysis, IDO expression was an independent prognostic factor for PFS (P=0.020). These results indicated that the high IDO expression was involved in the progression of endometrial cancer and correlated with the impaired clinical outcome, suggesting that IDO is a novel and reliable prognostic indicator for endometrial cancer.

Effect of Indirect Nonequilibrium Atmospheric Pressure Plasma on Anti-Proliferative Activity against Chronic Chemo-Resistant Ovarian Cancer Cells In Vitro and In Vivo

Purpose Nonequilibrium atmospheric pressure plasma (NEAPP) therapy has recently been focused on as a novel medical practice. Using cells with acquired paclitaxel/cisplatin resistance, we elucidated effects of indirect NEAPP-activated medium (NEAPP-AM) exposure on cell viability and tumor growth in vitro and in vivo. Methods Using chronic paclitaxel/cisplatin-resistant ovarian cancer cells, we applied indirect NEAPP-exposed medium to cells and xenografted tumors in a mouse model. Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in the above-mentioned EOC cells. Results We assessed the viability of NOS2 and NOS3 cells exposed to NEAPP-AM, which was prepared beforehand by irradiation with NEAPP for the indicated time. In NOS2 cells, viability decreased by approximately 30% after NEAPP-AM 120-sec treatment (P<0.01). The growth-inhibitory effects of NEAPP-AM were completely inhibited by N-acetyl cysteine treatment, while L-buthionine-[S, R]-sulfoximine, an inhibitor of the ROS scavenger used with NEAPP-AM, decreased cell viability by 85% after NEAPP-AM 60-sec treatment(P<0.05) and by 52% after 120 sec, compared to the control (P<0.01). In the murine subcutaneous tumor-formation model, NEAPP-AM injection resulted in an average inhibition of the NOS2 cell-inoculated tumor by 66% (P<0.05) and NOS2TR cell-inoculated tumor by 52% (P<0.05), as compared with the control. Conclusion We demonstrated that plasma-activated medium also had an anti-tumor effect on chemo-resistant cells in vitro and in vivo. Indirect plasma therapy is a promising treatment option for EOC and may contribute to a better patient prognosis in the future.

Role of the immunosuppressive enzyme indoleamine 2,3-dioxygenase in the progression of ovarian carcinoma

OBJECTIVE Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-catabolizing enzyme that induces immune tolerance. The purpose of the present study is to investigate IDO expression and its functional role in ovarian cancer cells in vitro and in vivo. METHODS IDO expression was immunohistochemically scored in surgically-resected ovarian cancer tissues (n=60), and its association with tumor-infiltrating lymphocyte (TIL) count or patient survival was analyzed. Next, IDO cDNA was transfected into the human ovarian carcinoma cell line SKOV3, establishing stable clones of IDO-overexpressing cells (SK-IDO). SK-IDO cells were characterized in vitro as well as in vivo using a nude mouse xenograft model. RESULTS High IDO expression in tumor cells was found in 34 (56.7%) cases and was correlated with a reduced number of CD8+ TIL. Patients with high IDO expression had significantly impaired overall and progression-free survival compared to patients with no or low IDO expression. There were no significant differences in in vitro cell proliferation, migration, invasion, or chemosensitivity to paclitaxel between the SK-IDO and control vector-transfected (SK-pcDNA) cells. However, tumor peritoneal dissemination was significantly increased in SK-IDO-xenografted mice compared to SK-pcDNA-xenografted mice. This tumor-progressive effect in SK-IDO-xenografted mice was abrogated by oral administration of the IDO inhibitor 1-methyl-tryptophan (1-MT). Finally, treatment with weekly i.p. paclitaxel combined with daily administration of 1-MT significantly prolonged the survival of the SK-IDO-xenografted mice compared to treatment with paclitaxel alone. CONCLUSIONS These results suggest that IDO is involved in ovarian cancer progression in vivo and may be a promising therapeutic target for advanced ovarian cancer.

Inverse Correlation between Tumoral Indoleamine 2,3-Dioxygenase Expression and Tumor-Infiltrating Lymphocytes in Endometrial Cancer: Its Association with Disease Progression and Survival

Purpose: Tumor escape from host immune systems is a crucial mechanism for disease progression. We recently showed that the immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO) is a prognostic indicator for endometrial cancer. The purpose of the present study was to investigate the relationship between IDO expression and tumor-infiltrating lymphocytes (TIL) or natural killer (NK) cells and to clarify their prognostic effect in endometrial cancer. Experimental Design: Immunohistochemical staining for IDO expression in endometrial cancer tissues (n = 65) was done. Tumor-infiltrating CD3+ and CD8+ lymphocytes, as well as CD57+ NK cells, were counted in serial tissue sections. Results: High IDO expression in tumor cells was found in 32 of 65 cases and was positively correlated with myometrial invasion, nodal metastasis, and lymph-vascular space involvement. We also found a significant correlation between high IDO expression and reduced numbers of CD3+, CD8+, and CD57+ cells infiltrating into both the tumor epithelium and stroma. Patients with high IDO expression, a low number of stromal CD3 (<60), low intraepithelial CD8 (<25), or low stromal CD8 (<40) had significantly impaired progression-free survival. On multivariate analysis, IDO expression and the number of stromal CD3+ TILs were independent prognostic factors for impaired progression-free survival. Conclusions: Tumoral IDO expression correlated with a reduced number of TILs and NK cells in endometrial cancer, possibly contributing to disease progression and impaired clinical outcome. These findings suggest that targeting IDO to restore host antitumor immunity may be a therapeutic strategy for endometrial cancer.

Expression of Twist increases the risk for recurrence and for poor survival in epithelial ovarian carcinoma patients

Twist is a transcription factor that regulates the expression of tumour suppressors such as E-cadherin. We examined the distribution and expression of Twist in human epithelial ovarian carcinoma (EOC) to examine its clinical significance. Paraffin sections from EOC tissues (n=82) were immunostained with Twist antibody, and the staining intensity was evaluated. The clinicopathological factors examined were age, International Federation of Gynecology and Obstetrics staging, histological type, tumour grade, preoperative value of CA125, peritoneal cytology, volume of ascites and residual tumour after cytoreductive surgery. Overall survival (OS) and progression-free survival (PFS) were evaluated using the Kaplan–Meier method, and multivariate analysis was performed using the Cox proportional hazard analysis. Of the 82 carcinomas, 49 (59.8%) cases were negative for Twist immunoexpression, and 33 (40.2%) were positive immunoexpression. When categorized into negative vs positive expression, Twist was not associated with any of the clinicopathological parameters examined. However, positive Twist expression significantly predicted poorer OS and PFS when compared with negative expression (P<0.0001). In the multivariate analyses, positive Twist expression was the only independent prognostic factor for survival in this study (P<0.0001). Positive Twist expression seems to be a useful marker in patients with EOC likely to have an unfavourable clinical outcome.

Angiotensin II type 1 receptor expression in ovarian cancer and its correlation with tumour angiogenesis and patient survival

Angiotensin II, a main effector peptide in the renin–angiotensin system, acts as a growth-promoting and angiogenic factor via type 1 angiotensin II receptors (AT1R). We have recently demonstrated that angiotensin II enhanced tumour cell invasion and vascular endothelial growth factor (VEGF) secretion via AT1R in ovarian cancer cell lines in vitro. The aim of the present study was to determine whether AT1R expression in ovarian cancer is correlated with clinicopathological parameters, angiogenic factors and patient survival. Immunohistochemical staining for AT1R, VEGF, CD34 and proliferating cell nuclear antigen (PCNA) were analysed in ovarian cancer tissues (n=67). Intratumour microvessel density (MVD) was analysed by counting the CD34-positive endothelial cells. Type 1 angiotensin II receptors were expressed in 85% of the cases examined, of which 55% were strongly positive. Type 1 angiotensin II receptors expression was positively correlated with VEGF expression intensity and MVD, but not with histological subtype, grade, FIGO stage or PCNA labelling index. In patients who had positive staining for AT1R, the overall survival and progression-free survival were significantly poor (P=0.041 and 0.017, respectively) as compared to those in patients who had negative staining for AT1R, although VEGF, but not AT1R, was an independent prognostic factor on multivariate analysis. These results demonstrated that AT1R correlated with tumour angiogenesis and poor patient outcome in ovarian cancer, suggesting its clinical potential for a novel molecular target in strategies for ovarian cancer treatment.

Inhibition of APN/CD13 leads to suppressed progressive potential in ovarian carcinoma cells.

BackgroundAminopeptidase N (APN/CD13), a 150-kDa metalloprotease, is a multifunctional cell surface aminopeptidase with ubiquitous expression. Recent studies have suggested that APN/CD13 plays an important role in tumor progression of several human malignancies. In the current study, we investigated the role of APN/CD13 in ovarian carcinoma (OVCA) progression.MethodsWe first examined the expression of APN/CD13 at the protein level in a variety of OVCA cell lines and tissues. We subsequently investigated whether there was a correlation between APN/CD13 expression and invasive potential of various OVCA cell lines. Moreover, we investigated the function of APN/CD13 in OVCA cells using bestatin, an APN/CD13 inhibitor, or transfection of siRNA for APN/CD13.ResultsWe confirmed that APN/CD13 was expressed in OVCA tissues and cell lines to various extents. There was a positive correlation between APN/CD13 expression and migratory potential in various OVCA cell lines with accordingly enhanced secretion of endogenous MMP-2. Subsequently, we found a significant decrease in the proliferative and migratory abilities of OVCA cells after the addition of bestatin or the inhibition of APN/CD13 expression by siRNA. Furthermore, in an animal model, daily intraperitoneal administration of bestatin after inoculation of OVCA cells resulted in a decrease of peritoneal dissemination and in prolonged survival of nude mice.ConclusionThe current data indicate the possible involvement of APN/CD13 in the development of OVCA, and suggest that clinical use of bestatin may contribute to better prognosis for ovarian carcinoma patients.