Clinicopathological features and programmed death-ligand 1 immunohistochemical expression in a multicenter cohort of uterine and ovarian melanomas: a retrospective study in Japan (KCOG-G1701s)

The objective of this study was to propose prognostic factors and optimal treatment strategies by analyzing the clinicopathological features and programmed death-ligand 1 (PD-L1) expression. We analyzed 31 patients diagnosed with uterine or ovarian melanoma between 1997 and 2017 in the Kansai Clinical Oncology Group/Intergroup. Twenty-four and seven patients with cervical and ovarian melanomas were included, respectively. Immune checkpoint inhibitors were used in seven patients, and the objective response rate was 40%. Notably, two patients with objective responses had a high PD-L1 expression. Ten and four patients with cervical and ovarian melanomas, respectively, had high PD-L1 immunohistochemical expressions. Multivariate analysis revealed that tumor stage was an independent prognostic factor for progression-free survival in patients with cervical melanomas. In patients with ovarian melanomas, the 1-year cumulative progression-free and overall survival rates were 0 and 29%, respectively. Kaplan-Meier analyses revealed that age <60 years was associated with poorer progression-free and overall survivals in patients with ovarian melanomas. In patients with cervical melanomas, the 1-, 3-, and 5-year cumulative overall survival rates were 53, 32, and 16%, respectively. Histological atypia was associated with a poorer progression-free survival, but there was no difference in survival between patients who underwent radical hysterectomy and those who did not. The present study is a large cohort study of uterine and ovarian melanomas, which are aggressive tumors with a significantly poor prognosis, even after standard surgery and adjuvant therapy. The use of immune checkpoint inhibitors is a promising and effective treatment option.

Anti-tumor activity of dual inhibition of phosphatidylinositol 3-kinase and MDM2 against clear cell ovarian carcinoma

INTRODUCTION

PI3K pathway signaling has received attention as a molecular target in clear cell ovarian carcinoma (CCOC). MDM2 is one of the AKT effectors in the PI3K pathway, which binds to and degrades p53. In this study, we aimed to clarify the prognostic significance of PIK3CA and MDM2 expression, and potential therapeutic effect of a dual inhibition of the PI3K pathway and MDM2.

MATERIALS AND METHODS

cDNA expression was evaluated by using microarray data using 75 samples of CCOC. DS-7423 (dual inhibitor of pan-PI3K and mTOR) and RG7112 (MDM2 inhibitor) were used on CCOC cell lines to evaluate cell proliferation, expression level of MDM2 related proteins, and apoptosis by MTT assay, western blotting, and flow cytometry. DS-7423 (3 mg/kg) and/or RG7112 (50 mg/kg) were orally administrated every day for three weeks, and the anti-tumor effect was evaluated using tumor xenografts, along with immunohistochemistry.

RESULTS

Tumors with high expression of both PIK3CA and MDM2 showed significantly worse prognosis in expression array of 71 CCOCs (P = 0.013). Dual inhibition of the PI3K pathway by DS-7423 and MDM2 by RG7112 showed synergistic anti-proliferative effect in 4 CCOC cell lines without TP53 mutations. The combination therapy more robustly induced pro-apoptotic proteins (PUMA and cleaved PARP) with increase of sub G1 population and apoptotic cells, compared with either single agent alone. The combination therapy significantly reduced tumor volume in mice (P < 0.001 in OVISE, and P = 0.038 in RMG-I) without severe body weight loss. Immunohistochemistry from the xenograft tumors showed that the combination treatment significantly reduced vascularity and cell proliferation, with an increase of apoptotic cell death.

CONCLUSION

A combination therapy targeting the PI3K pathway and MDM2 might be a promising therapeutic strategy in CCOC.

Histone methyltransferase SMYD2 selective inhibitor LLY-507 in combination with poly ADP ribose polymerase inhibitor has therapeutic potential against high-grade serous ovarian carcinomas

Dysfunction of histone methylation is known to be related to cancer progression. The histone methyltransferase SMYD2 methylates histone protein H3 and non-histone proteins, including poly ADP ribose polymerase 1 (PARP1). There have been reports of SMYD2 overexpression in several types of cancers. However, there are no reports regarding its role in high-grade serous ovarian carcinomas (HGSOCs). Therefore, we investigated the expression profile and conducted functional analysis on SMYD2 in HGSOC cells. In addition, we verified whether SMYD2 inhibition increases the susceptibility of HGSOC cells to PARP inhibitors. We analyzed the expression of histone methyltransferase SMYD2 by quantitative real-time polymerase chain reaction and immunohistochemistry using HGSOC clinical tissues (n = 35). We performed functional analyses, including cell proliferation assay, cell cycle analysis, and immunoblotting, after treatment with SMYD2 siRNAs and SMYD2 selective inhibitor LLY-507 in HGSOC cells. We also performed colony-formation assay after combination treatment with LLY-507 and PARP inhibitor olaparib in HGSOC cells. The expression profiles of SMYD2 showed significant overexpression of SMYD2 in HGSOC clinical tissues. The knockdown or inhibition of SMYD2 by siRNAs or LLY-507, respectively, suppressed cell growth by increasing the proportion of apoptotic cells. LLY-507 showed additive effect with olaparib in the colony-formation assay. These findings suggest that LLY-507 can be used alone or in combination with a PARP inhibitor for the treatment of patients with HGSOC.

Kaempferol, a natural dietary flavonoid, suppresses 17β-estradiol-induced survivin expression and causes apoptotic cell death in endometrial cancer

Endometrioid endometrial carcinoma, commonly known as type 1 endometrial cancer, accounts for >80% of endometrial carcinomas and is dependent on estrogen. We recently reported on the prognostic significance of the BIRC5 survivin gene in endometrial cancer. Estradiol induces survivin expression in estrogen receptor-positive, but not in estrogen receptor-negative, cancer cells. Kaempferol, a bioflavonoid, reportedly inhibits estrogen receptor-α (ERα) in hormone receptor-positive breast cancer cells. However, whether kaempferol-mediated inhibition of ERα suppresses survivin and induces cell death in endometrial cancer remains unclarified. The present study evaluated the antitumor effects of kaempferol on endometrial cancer cells. Cell viability assays, flow cytometry analysis, western blotting and annexin V analyses were used to analyze the antitumor effects of kaempferol. The results demonstrated that kaempferol successfully suppressed the viability of two ER-positive endometrial cancer cell lines, with IC₅₀ values of 83 and 65 µM. In addition, kaempferol induced sub-G1 cell accumulation and apoptotic cell death (P<0.01) in a dose-dependent manner. Treatment of cells with estradiol significantly induced co-expression of nuclear ERα and survivin proteins (P<0.001). Further evaluation revealed that kaempferol causes apoptotic cell death largely by suppressing ERα, survivin and Bcl-2 protein. Therefore, the results of the present study suggested that targeting ERα and survivin with kaempferol may be a novel therapeutic option against endometrial carcinoma.

Oncogenic histone methyltransferase EZH2: A novel prognostic marker with therapeutic potential in endometrial cancer

The histone methyltransferase EZH2, a key epigenetic modifier, is known to be associated with human tumorigenesis. However, the physiological importance of EZH2 and its clinical relevance in endometrial cancer remain unclear. Hence, in the present study, we investigated the expression and function of EZH2 in endometrial cancer. In a quantitative real-time PCR analysis of 11 endometrial cancer cell lines and 52 clinical endometrial cancer specimens, EZH2 was significantly overexpressed in cancer cells and tissues compared to that in corresponding normal control cells and tissues. Kaplan-Meier survival analysis using data of the TCGA RNA-seq database and tissue microarrays (TMAs) indicated that EZH2 overexpression is associated with endometrial cancer prognosis. In addition, knockdown of EZH2 using specific siRNAs resulted in growth suppression and apoptosis induction of endometrial cancer cells, accompanied by attenuation of H3K27 trimethylation. Consistent with these results, treatment with GSK126, a specific EZH2 inhibitor, suppressed endometrial cancer cell growth and decreased the number of cancer cell colonies. Furthermore, GSK126 showed additive effects with doxorubicin or cisplatin, which are conventional drugs for treatment of endometrial cancer. Further studies should explore the therapeutic potential of inhibiting EZH2 in patients with endometrial cancer.

Phase 1 dose-escalation study of single-agent veliparib in Japanese patients with advanced solid tumors

Veliparib (ABT‐888) is a potent, orally bioavailable poly(ADP‐ribose) polymerase‐1 and ‐2 inhibitor. This phase 1 study evaluated the tolerability, pharmacokinetic profile, safety, and preliminary antitumor activity of single‐agent veliparib in Japanese patients with advanced solid tumors. Eligible patients were assigned to treatment with veliparib at 200 or 400 mg dose; veliparib was self‐administered orally twice daily on days 1–28 of 28‐day cycles. Dose escalation, following a 3 + 3 design, defined dose‐limiting toxicities, the maximum tolerated dose, and the recommended phase 2 dose. Sixteen patients were enrolled (median age, 59 years). Fourteen patients had high‐grade serous ovarian cancer, one had primary peritoneal cancer, and one had BRCA‐mutated breast cancer. The most frequent treatment‐emergent adverse events were nausea and vomiting (93.8% each), decreased appetite (62.5%), abdominal pain, diarrhea, and malaise (31.3% each). A grade ≥3 toxicity was observed in 50% of patients; one patient each in the 200 mg (n = 4) and 400 mg (n = 12) cohorts experienced serious adverse events. Dose‐limiting toxicities were observed for one patient at the 400 mg dose. No toxicities leading to death were reported. The recommended phase 2 dose was defined as 400 mg twice daily. The veliparib pharmacokinetic profile was consistent with that reported for the Western population. Two patients, both with ovarian cancer, had a RECIST partial response. Veliparib monotherapy showed manageable tolerability and safety profiles and a predictable pharmacokinetic profile at a 400 mg twice‐daily dose, and supports the inclusion of Japanese patients in the multinational phase 3 study (NCT02470585).

Autophagy inhibition augments resveratrol-induced apoptosis in Ishikawa endometrial cancer cells

Resveratrol (RSV), a polyphenolic compound derived from red wine, inhibits the proliferation of various types of cancer. RSV induces apoptosis in cancer cells, while enhancing autophagy. Autophagy promotes cancer cell growth by driving cellular metabolism, which may counteract the effect of RSV. The present study aimed to elucidate the correlation between RSV and autophagy and to examine whether autophagy inhibition may enhance the antitumor effect of RSV in endometrial cancer cells. Cell proliferation, cell cycle progression and apoptosis were examined, following RSV exposure, by performing MTT assays, flow cytometry and annexin V staining, respectively, in an Ishikawa endometrial cancer cell line. Autophagy was evaluated by measuring the expression levels of light chain 3, II (LC3-II; an autophagy marker) by western blotting and immunofluorescence. Chloroquine (CQ) and small interfering RNAs targeting autophagy related (ATG) gene 5 (ATG5) or 7 (ATG7) were used to inhibit autophagy, and the effects in combination with RSV were assessed using MTT assays. RSV treatment suppressed cell proliferation in a dose-dependent manner in Ishikawa cells. In addition, RSV exposure increased the abundance of the sub-G1 population and induced apoptosis. LC3-II accumulation was observed following RSV treatment, indicating that RSV induced autophagy. Combination treatment with CQ and RSV more robustly suppressed growth inhibition and apoptosis, compared with RSV treatment alone. Knocking down ATG5 or ATG7 expression significantly augmented RSV-induced apoptosis. The results of the present study indicated that RSV-induced autophagy may counteract the antitumor effect of RSV in Ishikawa cells. Combination treatment with RSV and an autophagy inhibitor, such as CQ, may be an attractive therapeutic option for treating certain endometrial cancer cells.

Advanced Mucinous Adenocarcinoma Arising from a Mature Cystic Teratoma: A Case Report and Literature Review

Purpose

To describe the postoperative progressive course of advanced-stage adenocarcinoma arising from a mature cystic teratoma (MCT) and review the literature regarding this disease.

Methods

A 59-year-old woman visited our hospital with an abdominal mass. Laparotomy showed enlargement of the left ovary and dissemination throughout the abdominal and pelvic cavities. The diagnosis was FIGO stage IIIB adenocarcinoma arising from a MCT. We report this case in detail with a review of the literature.

Results

A literature search yielded 9 cases of stage III adenocarcinoma with malignant transformation. Six of these 9 patients died within 12 months after diagnosis. Of the 8 patients who underwent postoperative chemotherapy, 3 survived for over 39 months. The review indicates that prognosis of adenocarcinoma is as poor as that for squamous cell carcinoma arising from a MCT.

Conclusions

In general, as with this case, prognosis of advanced adenocarcinoma associated with a MCT is poor. However, we should be aware that not all patients are resistant to chemotherapy.

Significance of survivin as a prognostic factor and a therapeutic target in endometrial cancer

INTRODUCTION

Survivin is an anti-apoptotic protein encoded by the baculoviral inhibitor of apoptosis repeat-containing (BIRC5) gene and is upregulated in 83% of endometrial cancers. We aimed to elucidate the prognostic importance of BIRC5 expression, and evaluate survivin as a therapeutic target for endometrial cancer, by knock-down of BIRC5 and using the survivin inhibitor-YM155.

METHODS

RNA sequencing data in 234 patients with endometrial carcinoma was obtained from The Cancer Genome Atlas database, and analyzed using Kaplan-Meier method, log-rank test and Cox proportional hazard model. Expressions of survivin in 16 endometrial cancer cell lines were analyzed by western blotting. Knocking down effect on survivin expression was evaluated using a small interfering RNA (siRNA). The anti-proliferative and pro-apoptotic effects of YM155 were assessed with cell viability, flow cytometry, and annexin V/propidium iodide assays.

RESULTS

High expression of BIRC5 was associated with poor progression free survival (P=0.006), and shown to be an independent prognostic factor (HR=1.97, 95% CI=1.29-4.5, P=0.045). Survivin was upregulated in 14 of 16 (87.5%) endometrial cancer cell lines, compared with endometrial immortalized cells. Apoptosis was induced by knockdown of BIRC5 in all 3 cell lines examined. YM155 showed increased population of sub-G1 cells (P<0.001) in all 16 cell lines, and IC50 values to YM155 were <50nm in 15 cell lines. YM155 dose-dependently and significantly increased the apoptotic cell population in all 16 cell lines (P<0.001).

CONCLUSIONS

Present study indicated that survivin expression is a significant prognostic factor and that survivin is a promising therapeutic target for endometrial cancer.

Abstract 3614: The anti-tumor effect of antimalarial chloroquine on endometrial cancer cells is dependent on autophagy inhibition

Introduction: Autophagy, which literally means ‘self-eating’, is a major lysosomal degradation system of cytoplasmic materials. Autophagy plays roles in promoting tumor growth by fueling energy and inducing resistance to chemotherapy and/or irradiation in various types of human cancer. However, the roles of autophagy have not been well investigated in endometrial cancer. Chloroquine (CQ) was originally developed as an anti-malarial agent, discovered in 1934. It has also been known as an autophagy inhibitor. In this study, we investigated the anti-tumor effect and inhibition of autophagy by CQ in endometrial cancer cells.

Methods: Cell proliferation and cell cycle in response to CQ were assessed in Ishikawa, AN3CA and KLE endometrial cancer cell lines by MTT assay and flow cytometry, respectively. The autophagic activity and autophagosome formation were monitored by LC3 expression in Western blotting and immunofluorescence. The effect of knockdown of either ATG5 or ATG7, both of which are indispensable for induction of autophagy, was also assessed by MTT assay. The sensitivity to CQ was compared between parental and cisplatin-resistant (CP-r) Ishikawa cells.

Results: CQ attenuated proliferation of all the three endometrial cancer cell lines in a dose dependent manner. The IC50 values were from 1.5 to 12 uM, which were estimated to be lower than clinical dose of 250 mg daily. CQ induced apoptosis in these cells. Inhibition of autophagy by knocking down either ATG5 or ATG7 decreased the sensitivity to CQ in Ishikawa cells, suggesting that the anti-tumor effect of CQ is dependent on inhibition of autophagy. Exposure to cisplatin increased the level of basal autophagy, and the sensitivity to cisplatin was improved by knocking down ATG5 or ATG7. In addition, CP-r Ishikawa cells acquired higher level of autophagic activity, and the CP-r cells retained the sensitivity to cisplatin by autophagy inhibition by CQ.

Conclusions: Our data suggest that autophagy is involved in endometrial tumor growth, and that CQ might be a promising therapeutic agent as an autophagy inhibitor in endometrial cancer. In addition, CQ might retain the sensitivity to cisplatin in cisplatin-resistant endometrial cells, through the suppression of the increased level of autophagy.

Citation Format: Tomohiko Fukuda, Katsutoshi Oda, Osamu Wada-Hiraike, Kenbun Sone, Kanako Inaba, Yuji Ikeda, Tomoko Kashiyama, Aki Miyasaka, Chinami Makii, Reiko Kurikawa, Takahide Arimoto, Tetsu Yano, Kei Kawana, Noboru Mizushima, Yutaka Osuga, Tomoyuki Fujii. The anti-tumor effect of antimalarial chloroquine on endometrial cancer cells is dependent on autophagy inhibition. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3614. doi:10.1158/1538-7445.AM2015-3614

Putative tumor suppression function of SIRT6 in endometrial cancer

SIRT6, a member of the sirtuin family, has been identified as a candidate tumor suppressor. To pursue the role of SIRT6 in endometrial cancer, we investigated the anti-tumorigenic function of SIRT6. The expression of SIRT6 negatively affected the proliferation of AN3CA and KLE endometrial cancer cells. Increased expression of SIRT6 resulted in the induction of apoptosis by repressing the expression of the anti-apoptotic protein survivin. Consistent with this result, a survivin inhibitor YM155 efficiently inhibited cellular proliferation and induced apoptosis. These results revealed that SIRT6 might function as a tumor suppressor of endometrial cancer cells.

PI3K/mTOR pathway inhibition overcomes radioresistance via suppression of the HIF1-α/VEGF pathway in endometrial cancer

Radiation therapy is a key therapeutic strategy for endometrial carcinomas. However, biomarkers that predict radiosensitivity and drugs to enhance this sensitivity have not yet been established. We aimed to investigate the roles of TP53 and MAPK/PI3K pathways in endometrial carcinomas and to identify appropriate radiosensitizing therapeutics. D10 values (the irradiating dose required to reduce a cell population by 90%) were determined in eight endometrial cancer cell lines with known mutational statuses for TP53, PIK3CA, and KRAS. Cells were exposed to ionizing radiation (2-6Gy) and either a dual PI3K/mTOR inhibitor (NVP-BEZ235) or a MEK inhibitor (UO126), and their radiosensitizing effects were evaluated using clonogenic assays. The effects of silencing hypoxia-inducible factor-1 α (HIF-1α) expression with small interfering RNAs (siRNAs) were evaluated following exposure to ionizing radiation (2-3Gy). D10 values ranged from 2.0 to 3.1Gy in three cell lines expressing wild-type TP53 or from 3.3 to more than 6.0Gy in five cell lines expressing mutant TP53. NVP-BEZ235, but not UO126, significantly improved radiosensitivity through the suppression of HIF-1α/vascular endothelial growth factor-A expression. HIF-1α silencing significantly increased the induction of the sub-G1 population by ionizing radiation. Our study data suggest that TP53 mutation and PI3K pathway activation enhances radioresistance in endometrial carcinomas and that targeting the PI3K/mTOR or HIF-1α pathways could improve radiosensitivity.

Abstract 1314: Aberrant expression of beta-catenin and cyclin D1 in endometrial cancer

Introduction:

Wnt/beta-catenin/cyclin D1 pathway has been suggested to be involved in cell proliferation in endometrioid endometrial carcinomas (EEC), in addition to the activation of the PI3K pathway via PIK3CA and/or PTEN mutations. We previously reported that the mutations of cyclin D1 (CCND1 gene) promotes cell proliferation in EEC. However, the role of beta-catenin and its relationship with cyclin D1 is not yet well known. In this study, we focused on alterations of beta-catenin and cyclin D1 and their clinical impact in EEC.

Methods:

This study was conducted under approval of ethics committee of the institute and informed consent from each patient. Expressions of cyclin D1 and beta-catenin were examined by tissue microarray in formalin fixed 120 samples of EEC. The expression levels were evaluated by two pathologists, and the staining was classified as overexpressed when &gt;50% of tumor cells showed strong staining in cytoplasm (for beta-catenin) and nucleus (for cyclin D1). Genomic DNA was isolated in 91 primary surgical specimens. Mutations of beta-catenin (exon 3 of CTNNB1 gene) and Cyclin D1 (exon 5 of CCND1 gene) were examined by PCR-direct sequencing. We constructed expression plasmid of various types of mutant beta-catenin and performed colony formation assay using these plasmids.

Result:

In 120 samples, beta catenin and cyclin D1 were overexpressed in 5 (4%) and 7 (6%) cases, respectively. Median follow-up period of these patients is 85 months. Interestingly, over-expression of these two proteins was not overlapped each other. In these 12 samples, 7 of 12 cases (58%) were stage III or IV. However, recurrence was only observed in one patient (5-year progression free survival rate is 92%). Mutations of CCND1 and CTNNB1 were detected in 2 (2%) and 9 (10%) cases, respectively. We confirmed that all these mutations are somatic. Mutations of CCND1 and CTNNB1 were also mutually exclusive. Although the two cases with CCND1 mutations died of disease, none of the nine cases with CTNNB1 mutations got recurrent (p=0.018 by Fisher's exact test). In colony formation assay, mutant beta-catenin at codon 32 and codon 37 did not increase the colony number, compared with wild-type beta-catenin (control), although mutants at codon 34 significantly augmented the colony formation.

Conclusion:

Aberrant expression of both beta-catenin and cyclin D1 are present in EEC, through mutations and/or overexpression, and alterations of beta-catenin might be associated with favorable prognosis. Our data suggest that function of mutant beta-catenin might be distinct among each mutation type. Further study is warranted to clarify the role of wnt/beta-catenin/cyclin D1 pathway in EEC.

Citation Format: Yuji Ikeda, Katsutoshi Oda, Takahiro Koso, Daichi Maeda, Osamu Wada Hiraike, Tomoko Kashiyama, Aki Miyasaka, Kei Kawana, Tetsu Yano, Yoshihiro Kikuchi, Masashi Fukayama, Yutaka Osuga, Tomoyuki Fujii. Aberrant expression of beta-catenin and cyclin D1 in endometrial cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1314. doi:10.1158/1538-7445.AM2014-1314

Abstract 2402: Antitumor effect of a poly (ADP-ribose) polymerase (PARP) inhibitor in endometrial carcinoma cell lines

The loss of PTEN is the most frequent genetic aberration in endometrial cancer. One of the phosphatase-independent roles of PTEN is associated with homologous recombination (HR) in the nucleus. Poly (ADP-ribose) polymerase (PARP) plays a key role in the repair of DNA single-strand breaks, and a PARP inhibitor induces synthetic lethality in cancer cells with HR deficiency. We examined the anti-tumor activity of olaparib, a PARP inhibitor, and its correlation between the sensitivity and status of PTEN in a panel of endometrial cancer cell lines.

Methods

The response to olaparib was evaluated using a clonogenic assay with SF50 values (concentration to inhibit cell survival to 50%) in 16 endometrial cancer cell lines. The effects of PTEN introduction on the sensitivity of cells to olaparib and ionizing radiation (IR) exposure were compared between parental HEC-6 (PTEN-null) and HEC-6 PTEN+ (stably expressing wild-type PTEN) cells by clonogenic assay, foci formation of RAD51 and γH2AX, and induction of cleaved PARP.

Results

The SF50 values were 100 nM or less in six of the 16 (38%: sensitive) cell lines; whereas, SF50 values were 1,000 nM or more in five of the 16 (31%: resistant) cell lines. PTEN mutations were not associated with sensitivity to olaparib (Mutant [n = 12]: 995 ± 1,096 nM; Wild-type [n = 4]: 144 ± 91 nM, p = 0.17 by Student'st test). RAD51 expression was observed broadly and was not associated with PTEN status in the 16 cell lines. The number of colonies in the clonogenic assay, the foci formation of RAD51 and γH2AX, and the induction of apoptosis were not affected by PTEN introduction in the HEC-6 PTEN+ cells. The expression level of nuclear PTEN was not elevated within 24 h following IR in the HEC-6-PTEN+ cells.

Conclusions

Our results suggest that olaparib, a PARP inhibitor, is effective on certain endometrial cancer cell lines. The inactivation of PTEN might not affect the DNA repair function. Predictive biomarkers are warranted to utilize olaparib in endometrial cancer.

Citation Format: Aki Miyasaka, Katsutoshi Oda, Yuji Ikeda, Tomoko Kashiyama, Takahiro Koso, Kanako Inaba, Tomohiko Fukuda, Chinami Makii, Kayo Asada, Reiko Kurikawa, Osamu Wada Hiraike, Kenbun Sone, Yuriko Uehara, Yoko Matsumoto, Takahide Arimoto, Hiroyuki Kuramoto, Tetsu Yano, Kei Kawana, Yutaka Osuga, Tomoyuki Fujii. Antitumor effect of a poly (ADP-ribose) polymerase (PARP) inhibitor in endometrial carcinoma cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2402. doi:10.1158/1538-7445.AM2014-2402

Anti-tumor activity of olaparib, a poly (ADP-ribose) polymerase (PARP) inhibitor, in cultured endometrial carcinoma cells

Background

PTEN inactivation is the most frequent genetic aberration in endometrial cancer. One of the phosphatase-independent roles of PTEN is associated with homologous recombination (HR) in nucleus. Poly (ADP-ribose) polymerase (PARP) plays key roles in the repair of DNA single-strand breaks, and a PARP inhibitor induces synthetic lethality in cancer cells with HR deficiency. We examined the anti-tumor activity of olaparib, a PARP inhibitor, and its correlation between the sensitivity and status of PTEN in endometrial cancer cell lines.

Methods

The response to olaparib was evaluated using a clonogenic assay with SF50 values (concentration to inhibit cell survival to 50%) in 16 endometrial cancer cell lines. The effects of PTEN on the sensitivity to olaparib and ionizing radiation (IR) exposure were compared between parental HEC-6 (PTEN-null) and HEC-6 PTEN + (stably expressing wild-type PTEN) cells by clonogenic assay, foci formation of RAD51 and γH2AX, and induction of cleaved PARP. The effects of siRNA to PTEN were analyzed in cells with wild-type PTEN.

Results

The SF50 values were 100 nM or less in four (25%: sensitive) cell lines; whereas, SF50 values were 1,000 nM or more in four (25%: resistant) cell lines. PTEN mutations were not associated with sensitivity to olaparib (Mutant [n = 12]: 746 ± 838 nM; Wild-type [n = 4]: 215 ± 85 nM, p = 0.26 by Student’s t test). RAD51 expression was observed broadly and was not associated with PTEN status in the 16 cell lines. The number of colonies in the clonogenic assay, the foci formation of RAD51 and γH2AX, and the induction of apoptosis were not affected by PTEN introduction in the HEC-6 PTEN + cells. The expression level of nuclear PTEN was not elevated within 24 h following IR in the HEC-6-PTEN + cells. In addition, knocking down PTEN by siRNA did not alter the sensitivity to olaparib in 2 cell lines with wild-type PTEN.

Conclusions

Our results suggest that olaparib, a PARP inhibitor, is effective on certain endometrial cancer cell lines. Inactivation of PTEN might not affect the DNA repair function. Predictive biomarkers are warranted to utilize olaparib in endometrial cancer.

Antitumor activity and induction of TP53-dependent apoptosis toward ovarian clear cell adenocarcinoma by the dual PI3K/mTOR inhibitor DS-7423

DS-7423, a novel, small-molecule dual inhibitor of phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR), is currently in phase I clinical trials for solid tumors. Although DS-7423 potently inhibits PI3Kα (IC50 = 15.6 nM) and mTOR (IC50 = 34.9 nM), it also inhibits other isoforms of class I PI3K (IC50 values: PI3Kβ = 1,143 nM; PI3Kγ = 249 nM; PI3Kδ = 262 nM). The PI3K/mTOR pathway is frequently activated in ovarian clear cell adenocarcinomas (OCCA) through various mutations that activate PI3K-AKT signaling. Here, we describe the anti-tumor effect of DS-7423 on a panel of nine OCCA cell lines. IC50 values for DS-7423 were <75 nM in all the lines, regardless of the mutational status of PIK3CA. In mouse xenograft models, DS-7423 suppressed the tumor growth of OCCA in a dose-dependent manner. Flow cytometry analysis revealed a decrease in S-phase cell populations in all the cell lines and an increase in sub-G1 cell populations following treatment with DS-7423 in six of the nine OCCA cell lines tested. DS-7423-mediated apoptosis was induced more effectively in the six cell lines without TP53 mutations than in the three cell lines with TP53 mutations. Concomitantly with the decreased phosphorylation level of MDM2 (mouse double minute 2 homolog), the level of phosphorylation of TP53 at Ser46 was increased by DS-7423 in the six cell lines with wild-type TP53, with induction of genes that mediate TP53-dependent apoptosis, including p53AIP1 and PUMA at 39 nM or higher doses. Our data suggest that the dual PI3K/mTOR inhibitor DS-7423 may constitute a promising molecular targeted therapy for OCCA, and that its antitumor effect might be partly obtained by induction of TP53-dependent apoptosis in TP53 wild-type OCCAs.

Abstract 525: Induction of apoptosis in ovarian clear cell carcinomas with wild-type TP53 by inhibiting PI3K/mTOR signaling pathway

Background:Epithelial ovarian cancer is a leading cause of death from gynecological malignancies.Ovarian clear cell adenocarcinoma (OCCA) is the second most common cause of death from ovarian cancer with a higher incidence in Asia, especially Japan (&gt;25%). Due to low response rates to conventional platinum-based chemotherapy, the clinical outcome is generally poor. PIK3CA mutations are frequent (&gt;40%) in OCCA compared with other histology types and overexpression of receptor tyrosine kinases (RTKs), including HER2 and cMET, is also frequently observed in OCCA.

Thus, the RTK-PI3K (phosphatidylinositol 3-kinase)/mTOR (mammalian target of rapamycin) signaling axis is broadly activated in OCCA. This study evaluated the anti-tumor efficacy of DS-7423, a novel PI3K/mTOR dual inhibitor, in a panel of OCCA cell lines. Material and methods: We evaluated the phosphorylation status of RTK-PI3K/mTOR signaling pathway in 9 OCCA cell lines. Four of those cell lines possessed PIK3CA mutations; 3 of the 5 remaining cell lines overexpressed HER2, HER3 and/or cMET. We determined the effect of DS-7423 by MTT assay, FACS analysis, and Western blotting. Apoptosis induction was detected by annexin-V and propidium iodide (PI) staining. Induction of p53 target genes, including p53AIP1, was evaluated by RT-PCR. Results: IC50 values for DS-7423 were &lt;100 nM for all 9 OCCA cell lines. Efficacy did not significantly differ between PIK3CA mutant and wild type OCCA cells. AKT and its downstream targets (GSK3β, FOXO1/3a, MDM2, 4EBP1, and S6) were phosphorylated in OCCA cell lines regardless of PIK3CA mutational status. DS-7423 suppressed the phosphorylation levels of AKT and its target proteins in all these OCCA cell lines. FACS analysis revealed an increase in sub-G1 cell populations by treatment at ≥156 nM DS-7423 in 6 out of 9 OCCA cell lines. In these 6 cell lines, the number of apoptotic cells, as determined by annexin-V and PI staining, increased in a dose-dependent manner and DS-7423 induced apoptosis more effectively in TP53 wild type OCCA cell lines than in TP53 mutant OCCA cell lines. In accordance with decreased phospho-MDM2 levels, phosphorylation levels of p53 (Ser46) were increased and expression of p53AIP1 and PUMA, genes regulating p53-dependent apoptosis, were induced by DS-7423 in these p53 wild type cells. We also evaluated the expression status of bcl-2 family proteins in the OCCA cell line OVISE, and observed that DS-7423 treatment induced up-regulation of proapoptotic Bim and down-regulation of anti-apoptotic Mcl-1. Conclusions: Dual PI3K/mTOR inhibitors such as DS-7423 may constitute a promising molecular targeted therapy for OCCA, regardless of PIK3CA status. DS-7423 may induce apoptosis via activation of p53 and bcl-2 family members. As p53 mutations ar generally rare in OCCA, DS-7423 might induce p53-dependent apoptosis in this cancer type.

Citation Format: Tomoko Kashiyama, Katsutoshi Oda, Yuji Ikeda, Yoshinobu Shiose, Yasuhide Hirora, Aki Miyasaka, Takahiro Koso, Kanako Inaba, Tomohiko Fukuda, Keiko Shoji, Michihiro Tanikawa, Kazunori Nagasaka, Osamu Hiraike-Wada, Kei Kawana, Hiroyuki Aburatani, Shunsuke Nakagawa, Tomoyuki Fujii, Tetsu Yano, Shiro Kozuma. Induction of apoptosis in ovarian clear cell carcinomas with wild-type TP53 by inhibiting PI3K/mTOR signaling pathway. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 525. doi:10.1158/1538-7445.AM2013-525

Abstract 1748: Cyclin D1 harboring T286I mutation promotes oncogenic activation in endometrial cancer

Introduction. Cyclin D1 is an important regulator of cell cycle progression. Phosphorylation of cyclin D1 at Thr-286 by GSK3beta triggers nuclear export and its cytoplasmic proteolysis via the 26S proteasome. Cyclin D1 overexpression is a common event in various types of human cancers; however,mutations of CCND1 (encoding cyclin D1) have been only reported in endometrial cancer and esophageal cancer. We previously reported T286I mutations of CCND1 in 2 endometrial carcinomas (2.3%). The objective of this study was to identify the functions of T286I mutant of cyclin D1 in endometrial cancer. Materials and methods. T286I mutant cyclin D1 (CD1-T286I) plasmid was generated using wild-type cyclin D1 (CD1-WT) plasmid via site-directed mutagenesis technique. pcDNA3 empty plasmid was used as a control (CD1-Ct). Using these plasmids, the functions of mutant CD1-T286I were analyzed by luciferase assays, immunofluorescence, western blotting and colony formation assays in HEK293T (kidney) and HEC-50B (endometrial cancer) cells, both of which do not possess CCND1 mutations. Statistical analysis was performed by student-T test and p&lt;0.05 was considered statistically significant. Result. Immunofluorescence and western blotting showed predominant accumulation of exogenous CD1-T286I in nucleus, whereas expression of exogenous CD1-WT and endogenous cyclin D1 were observed diffusely in cytoplasm and nucleus. Luciferase assay revealed that pRB1 expression was partially decreased by introduction of CD1-WT and that the pRB1 expression was further decreased by introduction of CD1-T286I (p=0.002). In colony formation assays, introduction of CD1-T286I significantly increased the colony number, compared with CD1-WT (p=0.007) and CD1-Ct. Conclusion. Stabilization and accumulation of mutant cyclin D1 (T286I) in the nucleus might overcome regulation by pRb and induce cell proliferation in certain endometrial cancers. Phosphorylation-dependent nuclear export of cyclin D1 at Thr286 might be critical for prevention of aberrant cell proliferation in human cells.

Citation Format: Yuji Ikeda, Katsutoshi Oda, Takahiro Koso, Aki Miyasaka, Tomoko Kashiyama, Osamu Hiraike-Wada, Daichi Maeda, Kei Kawana, Shunsuke Nakagawa, Osamu Tetsu, Yoshihiro Kikuchi, Tomoyuki Fujii, Tetsu Yano, Shiro Kozuma. Cyclin D1 harboring T286I mutation promotes oncogenic activation in endometrial cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1748. doi:10.1158/1538-7445.AM2013-1748

Genotype-dependent efficacy of a dual PI3K/mTOR inhibitor, NVP-BEZ235, and an mTOR inhibitor, RAD001, in endometrial carcinomas

The PI3K (phosphatidylinositol-3-kinase)/mTOR (mammalian target of rapamycin) pathway is frequently activated in endometrial cancer through various PI3K/AKT-activating genetic alterations. We examined the antitumor effect of NVP-BEZ235—a dual PI3K/mTOR inhibitor—and RAD001—an mTOR inhibitor—in 13 endometrial cancer cell lines, all of which possess one or more alterations in PTEN, PIK3CA, and K-Ras. We also combined these compounds with a MAPK pathway inhibitor (PD98059 or UO126) in cell lines with K-Ras alterations (mutations or amplification). PTEN mutant cell lines without K-Ras alterations (n = 9) were more sensitive to both RAD001 and NVP-BEZ235 than were cell lines with K-Ras alterations (n = 4). Dose-dependent growth suppression was more drastically induced by NVP-BEZ235 than by RAD001 in the sensitive cell lines. G1 arrest was induced by NVP-BEZ235 in a dose-dependent manner. We observed in vivo antitumor activity of both RAD001 and NVP-BEZ235 in nude mice. The presence of a MEK inhibitor, PD98059 or UO126, sensitized the K-Ras mutant cells to NVP-BEZ235. Robust growth suppression by NVP-BEZ235 suggests that a dual PI3K/mTOR inhibitor is a promising therapeutic for endometrial carcinomas. Our data suggest that mutational statuses of PTEN and K-Ras might be useful predictors of sensitivity to NVP-BEZ235 in certain endometrial carcinomas.

Abstract 1702: A novel diagnostic approach using genome-wide single nucleotide polymorphism arrays for ovarian metastases in endometrial cancers

[Introduction] Synchronous cancers involving ovaries as well as uterine corpus are well-known events in gynecologic malignancies. These tumors may be independently derived, non-metastatic tumors (Dual Primary tumors; DP) or a tumor from one organ with metastasis to the other (Single Primary tumor with Metastasis; SPM). In the majority of these synchronous endometrial and ovarian cancers, both tumors are histologically endometrioid adenocarcinomas, which may cause a diagnostic difficulty to distinguish DP and SPM. By genome-wide genotyping, single nucleotide polymorphism (SNP) arrays, we can obtain chromosomal copy number alterations (CNA) throughout the genome in a single assay. We hypothesized that the copy number profiles by SNP arrays might be highly informative for genetic diagnosis in the synchronous endometrioid adenocarcinomas. [Material and Methods] We genetically diagnosed ten tumors from five patients with synchronous endometrial and ovarian carcinomas, using 250K SNP typing arrays and mutational analysis of PIK3CA, PTEN, K-Ras and CTNNB1 (beta-catenin). We evaluated whether conventional pathological diagnosis is compatible with the genetic diagnosis. [Results] Three of the five patients show identical copy number alterations (CNA), including type, loci and degree of each alteration, between the endometrial and the ovarian carcinomas. The other two show CNA only in either endometrial or ovarian carcinoma. All the five tumors possess one or more genetic mutations in the genes examined. One patient showed mutations both in PIK3CA and PTEN at discordant sites between endometrial and ovarian carcinomas, whereas the other four showed concordant mutations. Together, four of the five were genetically diagnosed as SPM and the remaining one was as DP. The pathological diagnosis was not in agreement with the molecular diagnosis in four of the five cases. [Conclusion] Our data suggest that most of the copy number alterations might occur before metastases and that genome-wide genotyping may represent a useful approach to distinguish between SPM and DP in synchronous endometrial and ovarian carcinomas. As chromosomal instability is commonly observed in various types of tumors, SNP array genotyping might be applicable to synchronous tumors in other organs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1702. doi:1538-7445.AM2012-1702

Successful management of a ruptured endometrial cyst in acute leukemia

OBJECTIVE

To report a case of acute abdomen due to rupture of ovarian endometrial cysts, manifested as a first symptom of acute leukemia.

DESIGN

Case report.

SETTING

University hospital.

PATIENT(S)

A 28-year-old Japanese woman with acute abdomen.

INTERVENTION(S)

A diagnosis of rupture of endometrial cysts was made by ultrasonography and magnetic resonance imaging. A diagnosis of acute myeloid leukemia (FAB M5a subtype) was made by bone marrow aspiration.

MAIN OUTCOME MEASURE(S)

Remission-induction chemotherapy for leukemia was initiated. Meanwhile, endometrial cysts were managed expectantly. Once complete remission was achieved, laparoscopic surgery was attempted to remove ovarian cysts and abdominal fluid.

RESULT(S)

Patients tolerated laparoscopy with favorable postoperative course. Consolidation chemotherapy commenced without substantial delay.

CONCLUSION(S)

Accurate diagnosis, optimal timing of surgery, and minimally invasive surgery with laparoscopy enabled us to manage this high-risk case to a favorable outcome.

Molecular characterization of the Fusarium graminearum species complex in Japan

Members of the Fusarium graminearum species complex are important cereal pathogens worldwide and belong to one of at least nine phylogenetically distinct species. We examined 298 strains of the F. graminearum species complex collected from wheat or barley in Japan to determine the species and trichothecene chemotype. Phylogenetic analyses and species-diagnostic polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLPs) revealed the presence and differential distribution of F. graminearum sensu stricto (s. str.) and F. asiaticum in Japan. F. graminearum s. str. is predominant in the north, especially in the Hokkaido area, while F. asiaticum is predominant in southern regions. In the Tohoku area, these species co-occurred. Trichothecene chemotyping of all strains by multiplex PCR revealed significantly different chemotype compositions of these species. All 50 strains of F. graminearum s. str. were of a 15- or 3-acetyl deoxynivalenol type, while 173 (70%) out of 246 strains of F. asiaticum were of a nivalenol type. The possibility of gene flow between the two species was investigated by use of 15 PCR-RFLP markers developed in this study. However, no obvious hybrids were detected from 98 strains examined, including strains collected from regions where both species co-occur.

Pi35(t), a new gene conferring partial resistance to leaf blast in the rice cultivar Hokkai 188

The japonica rice cultivar Hokkai 188 shows a high level of partial resistance to leaf blast. For mapping genes conferring the resistance, a set of 190 F2 progeny/F3 families was developed from the cross between the indica rice cultivar Danghang-Shali, with a low level of partial resistance, and Hokkai 188. Partial resistance to leaf blast in the F3 families was assessed in upland nurseries. From a primary microsatellite (SSR) linkage map and QTL analysis using a subset of 126 F2 progeny/F3 families randomly selected from the above set, one major QTL located on chromosome 1 was detected in the vicinity of SSR marker RM1216. This QTL was responsible for 69.4% of the phenotypic variation, and Hokkai 188 contributed the resistance allele. Segregation analysis in the F3 families for partial resistance to leaf blast was in agreement with the existence of a major gene, and the gene was designated as Pi35(t). Another QTL detected on chromosome 8 was minor, explained 13.4% of the phenotypic variation, and an allele of Danghang-Shali increased the level of resistance in this QTL. Additional SSR markers of the targeted Pi35(t) region were further surveyed in the 190 F2 plants, and Pi35(t) was placed in a 3.5-cM interval flanked by markers RM1216 and RM1003.

[Clinical characteristics of acute non A to G hepatitis caring TTV-DNA]

We measured TTV-DNA using polymerase chain reaction method in twenty seven patients with acute non A to G hepatitis and 139 patients with known types of acute hepatitis. TTV-DNA was detected in 40.7% in the former and in 36.7% in the latter, which was not significantly different. In acute non A to G hepatitis, TTV-DNA was more common in the male and in patient with more advanced age, however, no remarkable difference was noted concerning clinical characteristics according to the existence of TTV. Therefore TTV does not seem to play a causative role in pathogenesis of acute non A to G hepatitis.

[High prevalence of TT virus(TTV) in patients with non A to non G fulminant hepatitis: differences of clinical features and prognosis between TTV positive and negative patients]

We detected TTV-DNA in sera from 36 patients with fulminant hepatitis(FH) and evaluated differences in clinical features and prognosis between TTV-DNA positive and negative patients with nonA-nonG FH. TTV-DNA in sera was measured by nested PCR. Twenty of 36 patients with FH were diagnosed nonA-nonG FH. The TTV-DNA in sera was detected in 14 patients(38.9%) with FH, 9(64%) showed nonA-nonG FH and 3 were HBV FH and 2 were drug-induced FH. Although we compared clinical features(gender, age, distribution history of blood transfusion, initial symptoms of hepatitis, and liver function tests) and prognosis between TTV positive and negative patients with nonA-nonG FH, there were no significant differences between the two groups. These data suggest that although TTV may be a infectious agent related to nonA-nonG FH, further study is needed to clarify the role of TTV in the pathogenesis of FH.

Electrophysiological characterization of the inhibitory effect of a novel peptide gurmarin on the sweet taste response in rats

The effect of an anti-sweet peptide, gurmarin purified from the leaves of Gymnema sylvestre, was studied electrophysiologically on taste responses of the rat chorda tympani. The action of gurmarin was highly specific to sweet taste so that responses to various sweeteners including sugars, sweet amino acids and an artificial sweetener, saccharin were all suppressed. The most effective pH at which the rat tongue was treated with gurmarin was found to be 4.5, which corresponds to the isoelectric point of the peptide. At this condition about 5 microM of gurmarin was sufficient to reveal maximal effect and this was still significant at 0.5 microM (2 micrograms/ml). Although the suppressed responses required several hours to attain complete recovery, anti-gurmarin serum shortened the recovery time considerably. On the other hand, intravenous injection of gurmarin did not cause any significant effects on taste responses at all. These results suggest that gurmarin acts on the apical side of the taste cell, possibly by binding to the sweet taste receptor protein.

Three-dimensional structure of gurmarin, a sweet taste-suppressing polypeptide

The solution structure of gurmarin was studied by two-dimensional proton NMR spectroscopy at 600 MHz. Gurmarin, a 35-amino acid residue polypeptide recently discovered in an Indian-originated tree Gymnema sylvestre, selectively suppresses the neural responses of rat to sweet taste stimuli. Sequence-specific resonance assignments were obtained for all backbone protons and for most of the side-chain protons. The three-dimensional solution structure was determined by simulated-annealing calculations on the basis of 135 interproton distance constraints derived from NOEs, six distance constraints for three hydrogen bonds and 16 dihedral angle constraints derived from coupling constants. A total of 10 structures folded into a well-defined structure with a triple-stranded antiparallel beta-sheet. The average rmsd values between any two structures were 1.65 +/- 0.39 A for the backbone atoms (N, C alpha, C) and 2.95 +/- 0.27 A for all heavy atoms. The positions of the three disulfide bridges, which could not be determined chemically, were estimated to be Cys3-Cys18, Cys10-Cys23 and Cys17-Cys33 on the basis of the NMR distance constraints. This disulfide bridge pattern in gurmarin turned out to be analogous to that in omega-conotoxin and Momordica charantia trypsin inhibitor-II, and the topology of folding was the same as that in omega-conotoxin.

Histological localization of the sweet taste receptor in rat taste buds by the use of gurmarin, a sweet taste-suppressing peptide

The binding site of gurmarin, a peptide inhibiting the sweet-taste sensation, was studied in taste buds in rat circumvallate papillae by means of a histochemical technique. Frozen sections of tongues were incubated with gurmarin conjugated with biotin and thereafter examined with a light microscope. Positive reactivity for the peptide was localized to the taste hairs, the apical projections of taste bud cells. The reaction appeared in about 10% of the circumvallate taste buds examined. As electrophysiological studies indicate that gurmarin suppresses the sweet-taste sensation at the level of reception, the present study suggests that the receptor for sweet taste is located on the taste hairs, and, furthermore, is present only in a certain, limited number of the taste buds.

Expression of the linear DNA plasmid pRS64 in the plant pathogenic fungus Rhizoctonia solani

The plant pathogenic isolate RI-64 of anastomosis group 4 of Rhizoctonia solani possesses three linear DNA plasmids (pRS64-1, -2, and -3). Unique poly(A)- RNA, 0.5 kb in length and hybridizable with the pRS64 DNAs was found in mycelial cells of the isolate RI-64. The overall homology at the nucleotide level between pRS64-1, -2, and -3, and the cDNA prepared from the poly(A)- RNA was 100%, 73%, and 84%, respectively. The open reading frames found in pRS64-1, -2, and -3 (ORF1-1, ORF2-1, and ORF3-1) are 68 amino acids long. The amino acids sequence showed no significant homology with known proteins. Extracts from Escherichia coli cells expressing ORF1-1 contain a specific protein of 7 kDa. Antisera raised against the ORF1-1 product obtained from E. coli cells cross-reacted with the specific proteins found in the mycelia. The results indicate that the DNA plasmids found in R. solani contain a sequence that encodes a specific protein which may be involved in determination of plant pathogenicity.

Amino acid sequence of sweet-taste-suppressing peptide (gurmarin) from the leaves of Gymnema sylvestre

The complete amino acid sequence of a sweet-taste-suppressing peptide, gurmarin, from the leaves of Gymnema sylvestre was determined by the Edman analysis of peptides derived from digests obtained with Staphylococcus aureus V8 protease, pyroglutamyl aminopeptidase, and lysyl endopeptidase. Gurmarin consists of 35 amino acid residues with an amino-terminal pyroglutamyl residue and has the molecular weight of 4,209. Gurmarin has no significant homology with other known proteins.

Electrophysiological and behavioral studies on the taste of umami substances in the rat

Electrophysiological and behavioral experiments were performed to reveal taste properties of "umami" substances such as monosodium glutamate (MSG) and disodium inosine monophosphate (IMP) in rats. To eliminate the taste effects of Na ions contained in these umami substances, we dissolved them in 0.01 mM amiloride, which is known to block sodium responses. In the electrophysiological study, taste responses of the whole chorda tympani nerve were recorded. The magnitude of responses to MSG (or IMP) at concentrations below 0.1 M (or 0.01 M) was less than 10% of that to 0.1 M NaCl. On the other hand, the mixtures of MSG and IMP showed responses 2-7 times larger than the arithmetric sum of the responses to each component of the mixtures. A new sweet taste inhibitor (Gymnema sylvestre extract) strongly suppressed neural responses to mixtures of MSG and IMP as well as sucrose, but only weakly or negligibly to individual solutions of these umami substances. In the behavioral study, the brief exposure two-bottle preference test and conditioned taste aversion paradigm were used. MSG was most preferred at 0.3 M (preference ratio = 57%), IMP, at 0.01 M (61%), and both were less preferred or rejected at higher concentrations. In contrast, mixtures of MSG and IMP were more preferred at a broad concentration range (e.g., 82% for 0.1 M MSG + 0.01 M IMP). Aversive conditioning to umami substances was generalized to sucrose, and vice versa, but not to 0.1 M NaCl, 0.01 M HCl, and 0.1 mM quinine hydrochloride.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel peptide isolated from the leaves of Gymnema sylvestre--I. Characterization and its suppressive effect on the neural responses to sweet taste stimuli in the rat

1. A new substance that suppressed selectively the neural responses of the rat to sweet taste stimuli was isolated from the leaves of Gymnema sylvestre. 2. The substance was proved to be a peptide consisting of 35 amino acids and having a molecular weight of about 4,000. 3. The inhibitory effect on the sweet responses appeared after treating the tongue surface with the peptide at a concentration of more than 1 x 10(-6) M.