Tatsuhiro Ohgami

Level of reactive oxygen species induced by p21WAF(1)/CIP(1) is critical for the determination of cell fate

p21WAF(1)/CIP(1) is a well‐known cell cycle regulatory protein which is overexpressed in several cancer cell lines, and known to determine cell fate. We generated three recombinant adenovirus vectors that expressed either the full‐length p21 (Ad‐p21F), a p21 mutant with a deletion of the C‐terminal proliferative cell nuclear antigen (PCNA) binding domain (Ad‐p21N), or a p21 mutant with a deletion of the N‐terminal cyclin‐dependent kinase binding domain (Ad‐p21C). We transfected these vectors into five cancer cell lines. Premature senescence was induced in all of the lines only following transfection with Ad‐p21N and Ad‐p21F. In addition, apoptosis was also induced in LoVo and HCT116 cells that harbored wild‐type p53 and the reactive oxygen species (ROS) level was higher than in senescent cells. Finally, the induction of apoptosis was inhibited by using siRNA to downregulate p53. This observation implies that there is a feedback signaling loop involving p21/ROS/p53 in apoptotic responses. It appears to be, at least in part, driven by high levels of p21 protein. Next, we investigated the cell death effect of endogenous p21 protein on cell fate using sodium butyrate (NaB). Treatment with 1 mM NaB or 2 to 5 mM NaB induced senescence or apoptosis, respectively. The level of intracellular ROS in 5 mM NaB treated cells was 2‐fold higher, compared with that in 1 mM NaB treated cells. We also demonstrated that DNA damage response signals including ataxia telangiectasia mutated, γH2AX, and p38 MAPK were involved in NaB‐induced cell death. The magnitude of intracellular ROS levels in response to p21 elicited either senescence or apoptosis in the cancer cell lines. (Cancer Sci 2009; 100: 1275–1283)

Sodium butyrate inhibits the self-renewal capacity of endometrial tumor side-population cells by inducing a DNA damage response

We previously isolated side-population (SP) cells from a human endometrial cancer cell line, Hec1, and determined that Hec1-SP cells have cancer stem–like cell features. In this study, we isolated SP cells and non-SP (NSP) cells derived from a rat endometrial cell line expressing human [12Val] KRAS (RK12V cells) and determined the SP phenotype. RK12V-SP cells showed self-renewal capacity, the potential to develop into stromal cells, reduced expression levels of differentiation markers, long-term proliferating capacity in cultures, and enhanced tumorigenicity, indicating that RK12V-SP cells have cancer stem–like cell features. RK12V-SP cells also display higher resistance to conventional chemotherapeutic drugs. In contrast, treatment with a histone deacetylases (HDAC) inhibitor, sodium butyrate (NaB), reduced self-renewal capacity and completely suppressed colony formation of RK12V-SP cells in a soft agar. The levels of intracellular reactive oxygen species (ROS) and the number of γH2AX foci were increased by NaB treatment of both RK12V-SP cells and RK12V-NSP cells. The expression levels of γH2AX, p21, p27, and phospho-p38 mitogen-activated protein kinase were enhanced in RK12V-SP cells compared with RK12V-NSP cells. These results imply that treatment with NaB induced production of intracellular ROS and DNA damage in both RK12V-SP and RK12V-NSP cells. Following NaB treatment, DNA damage response signals were enhanced more in RK12V-SP cells than in RK12V-NSP cells. This is the first article on an inhibitory effect of NaB on proliferation of endometrial cancer stem–like cells. HDAC inhibitors may represent an attractive antitumor therapy based upon their inhibitory effects on cancer stem–like cells. Mol Cancer Ther; 10(8); 1430–9. ©2011 AACR.

Association of MDM2 SNP309 and TP53 Arg72Pro polymorphisms with risk of endometrial cancer.

The incidence of endometrial cancer, a common gynecological malignancy, is increasing in Japan. We have previously shown that the ER/MDM2/p53/p21 pathway plays an important role in endometrial carcinogenesis. In the present study, we investigated the effects of germline single nucleotide polymorphisms in murine double minute 2 (MDM2) SNP309, TP53 Arg72Pro, ESR1 PvuII and XbaI, and p21 codon 31 on endometrial cancer risk. We evaluated these polymorphisms in DNA samples from 125 endometrial cancer cases and 200 controls using polymerase chain reaction-based restriction fragment length polymorphism. The association of each genetic polymorphism with endometrial cancer was examined by the odds ratio and 95% confidence interval, which were obtained using logistic regression analysis. The SNP309 GG genotype non-significantly increased the risk of endometrial cancer. The 95% confidence interval for the GG genotype vs. the TT genotype of MDM2 SNP309 was 1.76 (0.93–3.30). Endometrial cancer was not associated with tested SNP genotypes for TP53, ESR1 and p21. The combination of SNP309 GG + TG and TP53 codon 72 Arg/Arg significantly increased endometrial cancer risk. The adjusted OR was 2.53 (95% confidence interval, 1.03–6.21) and P for the interaction was 0.04. This result was supported by in vitro data showing that endometrial cancer cell lines with the SNP309 G allele failed to show growth inhibition by treatment with RITA, which reduces p53-MDM2 binding. The presence of the SNP309 G allele and TP53 codon 72 Arg/Arg genotype is associated with an increased risk of endometrial cancer in Japanese women.

Low-dose mithramycin exerts its anticancer effect via the p53 signaling pathway and synergizes with nutlin-3 in gynecologic cancers

MDM2 is a direct negative regulator of p53. The p53‐independent mdm2‐P1 and p53‐dependent mdm2‐P2 promoters have been recently shown to harbor Sp1 binding sites. Mithramycin, an inhibitor of Sp1 DNA binding, has been used clinically to treat hypercalcemia and some types of neoplastic disorders. In this study, we investigated the mechanisms behind the anticancer effect of mithramycin. In gynecologic cancer cells expressing wild‐type p53, mithramycin stabilized p53 and increased the expression of the p53 downstream target genes PUMA and p21, arrested the cell cycle, and induced apoptosis. This activation of the p53 signaling pathway was a specific effect of MTH at concentrations <50 nm. Mithramycin temporally decreased transcription of both the mdm2‐P1 and ‐P2 promoters. This was followed by a subsequent increase of mdm2‐P2 promoter activity by activated p53. Up‐regulated MDM2 was in its active form, and consequently attenuated p53 activity. Although mithramycin activated p53 and suppressed the growth of human gynecologic cancer cell xenografts in mice, this was accompanied with a secondary up‐regulation of MDM2. Combined treatment with mithramycin and nutlin‐3, a drug that inhibits MDM2–p53 interaction, overcame a secondary up‐regulation of MDM2 and synergistically inhibited cancer cell growth by inducing apoptosis through activation of the p53 signaling pathway. These observations provide a better understanding of the mechanisms of mithramycin activity, and suggest a potential role for combining mithramycin and nutlin‐3 as a chemotherapeutic treatment for gynecologic cancers. (Cancer Sci 2010; 101: 1387–1395)

GEP oncogene promotes cell proliferation through YAP activation in ovarian cancer.

G-protein-coupled receptors (GPCRs) and their ligands function in the progression of human malignancies. Gα12 and Gα13, encoded by GNA12 and GNA13, respectively, are referred to as the GEP oncogene and are implicated in tumor progression. However, the molecular mechanisms by which Gα12/13 activation promotes cancer progression are not fully elucidated. Here, we demonstrate elevated expression of Gα12/13 in human ovarian cancer tissues. Gα12/13 activation did not promote cellular migration in the ovarian cancer cell lines examined. Rather, Gα12/13 activation promoted cell growth. We used a synthetic biology approach using chimeric G proteins and GPCRs activated solely by artificial ligands to selectively trigger signaling pathways downstream of specific G proteins. We found that Gα12/13 promotes proliferation of ovarian cancer cells by activating the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway. Furthermore, we reveal that inhibition of YAP by short hairpin RNA or a specific inhibitor prevented the growth of ovarian cancer cells. Therefore, YAP may be a suitable therapeutic target in ovarian cancer.

Regulation of the Mechanism of TWIST1 Transcription by BHLHE40 and BHLHE41 in Cancer Cells

ABSTRACT BHLHE40 and BHLHE41 (BHLHE40/41) are basic helix-loop-helix type transcription factors that play key roles in multiple cell behaviors. BHLHE40/41 were recently shown to be involved in an epithelial-to-mesenchymal transition (EMT). However, the precise mechanism of EMT control by BHLHE40/41 remains unclear. In the present study, we demonstrated that BHLHE40/41 expression was controlled in a pathological stage-dependent manner in human endometrial cancer (HEC). Our in vitro assays showed that BHLHE40/41 suppressed tumor cell invasion. BHLHE40/41 also suppressed the transcription of the EMT effectors SNAI1, SNAI2, and TWIST1. We identified the critical promoter regions of TWIST1 for its basal transcriptional activity. We elucidated that the transcription factor SP1 was involved in the basal transcriptional activity of TWIST1 and that BHLHE40/41 competed with SP1 for DNA binding to regulate gene transcription. This study is the first to report the detailed functions of BHLHE40 and BHLHE41 in the suppression of EMT effectors in vitro. Our results suggest that BHLHE40/41 suppress tumor cell invasion by inhibiting EMT in tumor cells. We propose that BHLHE40/41 are promising markers to predict the aggressiveness of each HEC case and that molecular targeting strategies involving BHLHE40/41 and SP1 may effectively regulate HEC progression.

1481PDAPREPITANT FOR THE PREVENTION OF CHEMOTHERAPY-INDUCED NAUSEA AND VOMITING WITH A MODERATELY EMETOGENIC CHEMOTHERAPY: A MULTICENTER, PLACEBO-CONTROLLED, DOUBLE-BLIND, RANDOMIZED STUDY IN JAPANESE GYNECOLOGIC PATIENTS RECEIVING PACLITAXEL AND CARBOPLATIN

ABSTRACT Aim: Aprepitant is a new neurokinin-1 receptor antagonist developed as a treatment for chemotherapy-induced nausea and vomiting (CINV). Several reports have shown that aprepitant is very effective for the prevention of CINV with highly emetogenic chemotherapy (HEC) in cisplatin-based regimens. However the efficacy of aprepitant for moderately emetogenic chemotherapy (MEC), such as paclitaxel plus carboplatin (TC), is still unclear. We conducted a multicenter, placebo-controlled, double-blind, randomized study in Japanese gynecologic patients who received a TC regimen. Methods: This phase III, randomized, double-blind study enrolled patients from nine institutions with a diagnosis of ovarian, endometrial, or cervical cancer who were scheduled to receive paclitaxel (175-180mg/m2) and carboplatin (AUC=5-6) for the first time. Patients received aprepitant or placebo with a 5-HT3 antagonist (except palonosetron) and dexamethasone before chemotherapy. Patients recorded nausea and vomiting episodes in a diary. Endpoints were proportions of patients with no vomiting, no significant nausea and complete response ( no vomiting and no rescue medication) for five days after chemotherapy. Results: Of 324 randomized patients, 297 patients (151 in the aprepitant group; 146 in the placebo group) were evaluable for efficacy and toxicity. The percentages of patients with no vomiting (84.8% vs 61.6%, p Conclusions: The combination of aprepitant, a 5-HT3 antagonist, and dexamethasone demonstrated efficacy for CINV prevention with MEC in patients with gynecologic cancer receiving a TC regimen. Disclosure: All authors have declared no conflicts of interest.

Value of Intraoperative Cytological and Pathological Sentinel Lymph Node Diagnosis in Fertility-Sparing Trachelectomy for Early-Stage Cervical Cancer

Background and Objectives: Trachelectomy, a fertility-sparing surgery for early-stage cervical cancer, can be performed only when there is no extrauterine extension present. Therefore, identifying the sentinel lymph nodes (SLNs) and using them to obtain an intraoperative pathologic diagnosis can provide information on the feasibility and safety of trachelectomy. Our aim was to assess the value of an intraoperative SLN diagnosis. Methods: We retrospectively analyzed the accuracy of intraoperative imprint cytology and frozen-section examination in 201 patients at our institution in whom trachelectomy was planned. Results: All patients could be evaluated for SLNs; a total of 610 SLNs were analyzed. Although the specificity of both imprint cytology and frozen-section examination was 100.0%, the sensitivity was only 58.6 and 65.5%, respectively. The diagnostic sensitivity was higher in 2-mm slices along the short axis than on bisection along the longitudinal axis. Imprint cytology correctly diagnosed 2 patients who had false-negative results on frozen section. The nature of the metastatic foci that caused an intraoperative false-negative diagnosis was either micrometastasis or isolated tumor cells. Conclusions: The accuracy of intraoperative SLN diagnosis requires improvement, especially when small metastatic foci are present.

Uterine Myxoid Leiomyosarcoma with Tumor Embolism Extending into the Right Atrium

Uterine myxoid leiomyosarcoma (MLMS) is an extremely rare variant of uterine leiomyosarcoma; only 56 cases were reported from 1982 to 2013. Uterine MLMS is characterized by a myxoid appearance and highly malignant behavior. We herein report a case involving a 65-year-old woman with uterine MLMS with a large tumor embolism that reached the right atrium. A total abdominal hysterectomy, bilateral salpingooophorectomy, and tumor embolism resection with the use of a heart-lung machine were performed. Epirubicin-ifosfamide chemotherapy in the adjuvant setting led to reductions in both the tumor emboli and peritoneal dissemination. The patient retained a good quality of life for 10 months after the initial surgery. She then developed progressive disease despite treatment with pazopanib. She died of her disease 14 months after the initial surgery. Although complete surgical resection of the tumor is desirable, tumor reduction surgery followed by adjuvant chemotherapy might help to retain a good quality of life. This is the first reported case of a primary uterine MLMS with tumor emboli.

Pelvic abscess: A late complication of abdominal trachelectomy for cervical cancer: Pelvic abscess after trachelectomy

Only a few reports of pelvic abscess as a late complication of trachelectomy have been published to date. To evaluate the cases of pelvic abscess as a late complication of abdominal trachelectomy for cervical cancer.