Koichi Ida

Overexpression of Sirt1 is Associated With Poor Outcomes in Patients With Ovarian Carcinoma.

Sirtuin 1 (SIRT1), originally identified as a longevity gene, regulates DNA repair and metabolism by deacetylating target proteins such as p53. SIRT1 plays a key role in the pathophysiology of metabolic diseases and neurodegenerative disorders, and is considered to protect against age-related diseases including cancer. In contrast, SIRT1 may be oncogenic because its overexpression has been detected in many cancers. The aim of the present study was to clarify the expression and the role of SIRT1 in ovarian carcinoma (OvCa). The expression of SIRT1 was evaluated immunohistochemically in 16 cases of normal ovaries, 35 cases of endometriosis with/without carcinoma, and 68 cases of OvCa (endometrioid, 16; clear cell, 20; mucinous, 16; serous, 16). Staining results were evaluated semiquantitatively by the Immunoreactive Scoring System, and the relationships with clinicopathologic features and outcomes of patients were analyzed. The expression of SIRT1 was higher in endometrioid, mucinous, and clear-cell carcinomas than in the inclusion cysts of normal ovaries, but not in serous carcinoma (P=0.038). The expression of SIRT1 on OvCa did not correlate with age, stage, location of metastasis, or capsular penetration. However, elevated SIRT1 expression was a significant predictor of shorter survival in univariate (P=0.038) and multivariate (P=0.037) survival analyses, regardless of the tumor stage. Results of the present study suggest a positive role for SIRT1 in the development of OvCa and its potential as a novel therapeutic target.

Lipocalin 2 Enhances Migration and Resistance against Cisplatin in Endometrial Carcinoma Cells

Purpose Lipocalin 2 (LCN2) is a secretory protein that is involved in various physiological processes including iron transport. We previously identified LCN2 as an up-regulated gene in endometrial carcinoma, and found that the overexpression of LCN2 and its receptor, SLC22A17, was associated with a poor prognosis. However, the functions and mechanism of action of LCN2 currently remain unclear. Methods The LCN2-overexpressing endometrial carcinoma cell lines, HHUA and RL95-2, and LCN2-low-expressing one, HEC1B, were used. The effects of LCN2 on cell migration, cell viability, and apoptosis under various stresses, including ultraviolet (UV) irradiation and cisplatin treatment, were examined using the scratch wound healing assay, WST-1 assay, and Apostrand assay, respectively. Results LCN2-silencing using shRNA method significantly reduced the migration ability of cells (p<0.05). Cytotoxic stresses significantly decreased the viability of LCN2-silenced cells more than that of control cells. In contrast, LCN2 overexpression was significantly increased cisplatin resistance. These effects were canceled by the addition of the iron chelator, deferoxamine. After UV irradiation, the expression of phosphorylated Akt (pAkt) was decreased in LCN2-silenced cells, and the PI3K inhibitor canceled the difference induced in UV sensitivity by LCN2. The cisplatin-induced expression of pAkt was not affected by LCN2; however, the expression of p53 and p21 was increased by LCN2-silencing. Conclusions These results indicated that LCN2 was involved in the migration and survival of endometrial carcinoma cells under various stresses in an iron-dependent manner. The survival function of LCN2 may be exerted through the PI3K pathway and suppression of the p53-p21 pathway. These functions of LCN2 may increase the malignant potential of endometrial carcinoma cells.

SIRT1 Regulates the Chemoresistance and Invasiveness of Ovarian Carcinoma Cells

BACKGROUND: SIRT1 is a longevity gene that forestalls aging and age-related diseases including cancer, and has recently attracted widespread attention due to its overexpression in some cancers. We previously identified the overexpression of SIRT1 in ovarian carcinoma (OvCa) as a poor prognostic factor. However, mechanistic insights into the function of SIRT1 in OvCa have yet to be elucidated. METHODS: Quantitative real-time reverse PCR (qRT-PCR) and Western blotting were employed to examine the expression of SIRT1 in a panel of human OvCa cell lines. si-RNA or sh-RNA and cDNA technologies were utilized to knockdown or overexpress SIRT1, respectively. The effects of SIRT1 on proliferation and chemoresistance were examined using a WST-1 assay, and the underlying mechanisms were confirmed using an apoptotic assay, and the quantification of glutathione (GSH), and reactive oxygen species (ROS). The aggressiveness of SIRT1 was analyzed using in vitro invasion and migration assays. RESULTS: SIRT1 was more strongly expressed in OvCa cell lines than in the immortalized ovarian epithelium at the gene and protein levels. Stress up-regulated the expression of SIRT1 in dose- and time-dependent manners. SIRT1 significantly enhanced the proliferation (P < .05), chemoresistance (P < .05), and aggressiveness of OvCa cells by up-regulating multiple antioxidant pathways to inhibit oxidative stress. Further study into the overexpression of SIRT1 demonstrated the up-regulation of several stemness-associated genes and enrichment of CD44v9 via an as-yet-unidentified pathway. CONCLUSIONS: Our results suggest that SIRT1 plays a role in the acquisition of aggressiveness and chemoresistance by OvCa, and has potential as a therapeutic target for OvCa.

Lipocalin 2 attenuates iron-related oxidative stress and prolongs the survival of ovarian clear cell carcinoma cells by up-regulating the CD44 variant

ABSTRACT Ovarian clear cell carcinoma (CCC) arises from ovarian endometriosis. Intra-cystic fluid contains abundant amounts of free iron, which causes persistent oxidative stress, a factor that has been suggested to induce malignant transformation. However, the mechanisms linking oxidative stress and carcinogenesis in CCC currently remain unclear. Lipocalin 2 (LCN2), a multifunctional secretory protein, functions as an iron transporter as well as an antioxidant. Therefore, we herein examined the roles of LCN2 in the regulation of intracellular iron concentrations, oxidative stress, DNA damage, and antioxidative functions using LCN2-overexpressing (ES2), and LCN2-silenced (RMG-1) CCC cell lines. The results of calcein staining indicated that the up-regulated expression of LCN2 correlated with increases in intracellular iron concentrations. However, a DCFH-DA assay and 8OHdG staining revealed that LCN2 reduced intracellular levels of reactive oxygen species and DNA damage. Furthermore, the expression of LCN2 suppressed hydrogen peroxide-induced apoptosis and prolonged cell survival, suggesting an antioxidative role for LCN2. The expression of mRNAs and proteins for various oxidative stress-catalyzing enzymes, such as heme oxygenase (HO), superoxide dismutase (SOD), and glutathione peroxidase, was not affected by LCN2, whereas the intracellular concentration of the potent antioxidant, glutathione (GSH), was increased by LCN2. Furthermore, the expression of xCT, a cystine transporter protein, and CD44 variant 8-10 (CD44v), a stem cell marker, was up-regulated by LCN2. Although LCN2 increased intracellular iron concentrations, LCN2-induced GSH may catalyze and override oxidative stress via CD44v and xCT, and subsequently enhance the survival of CCC cells in oxidative stress-rich endometriosis.

Panobinostat Enhances Growth Suppressive Effects of Progestin on Endometrial Carcinoma by Increasing Progesterone Receptor and Mitogen-Inducible Gene-6

Although progestin has been used to treat endometrial hyperplasia and endometrial carcinoma (EC), its therapeutic efficacy is limited. In order to improve this, the underlining mechanisms of the effects of progestin need to be elucidated in more detail. In the present study, we examined the involvement of mitogen-inducible gene-6 (MIG6), a negative regulator of the EGF receptor, in the progestin-mediated growth suppression of endometrial epithelia. The immunohistochemical expression of MIG6 was elevated in the early to mid-secretory phases of normal endometrium and also with endometrial hyperplasia after medroxyprogesterone acetate (MPA) therapy. The addition of progesterone (P4) to progesterone receptor (PR)-positive EC cells reduced the viability and induced MIG6 messenger RNA (mRNA) and protein expression. The silencing of MIG6 using siRNA eliminated the P4-mediated reduction of EC cell viability, indicating that MIG6 is an essential downstream component of PR-mediated growth suppression. In order to enhance PR-driven signals, we examined the effects of histone deacetylase (HDAC) inhibitors because histone acetylation has been shown to increase the expression of PR. The addition of three HDAC inhibitors (panobinostat, LBH589; trichostatin A, TSA; suberoylanilide hydroxamic acid, SAHA) decreased the viability of EC cells and up-regulated the expression of PR and MIG6, and these effects were the strongest with LBH589. The addition of LBH589 and MPA synergistically decreased the viability and increased apoptosis in EC cells. These results indicate that LBH589 has potential as an enhancer of progestin therapy via the up-regulation of PR and MIG6.

The somatic mutations in Interferon-γ signal molecules in human uterine leiomyosarcoma

Human uterine leiomyosarcoma (Ut-LMS) is neoplastic malignancy that typically arises in tissues of mesenchymal origin. The identification of novel molecular mechanism leading to human UtLMS formation and the establishment of new therapies has been hampered by several critical points. We earlier reported that mice with a homozygous deficiency for proteasome subunit beta type (PSMB) 9, an interferon (IFN)-g inducible factor, spontaneously develop Ut-LMS. The use of research findings of the experiment with mouse model has been successful in increasing our knowledge and understanding of how alterations, in relevant oncogenic, tumor suppressive, and signaling pathways directly impact sarcomagenesis. The IFN-g signaling pathway is important for control of tumor growth and invasion and has been implicated in several malignant tumors. In this study, experiments with human tissues revealed a defective expression of PSMB9 in human Ut-LMS that was traced to the IFN-g signal cascade and the significant effect of somatic mutations of Janus kinase (JAK) 1 molecule or PSMB9 gene promoter region on the PSMB9 gene transcriptional activation. Understanding the molecular mechanisms of human Ut-LMS may lead to identification of new diagnostic candidates or therapeutic targets in human Ut-LMS.