Satoru Nagase

Mutational loss of PTEN induces resistance to NOTCH1 inhibition in T-cell leukemia

Gain-of-function mutations in NOTCH1 are common in T-cell lymphoblastic leukemias and lymphomas (T-ALL), making this receptor a promising target for drugs such as γ-secretase inhibitors, which block a proteolytic cleavage required for NOTCH1 activation. However, the enthusiasm for these therapies has been tempered by tumor resistance and the paucity of information on the oncogenic programs regulated by oncogenic NOTCH1. Here we show that NOTCH1 regulates the expression of PTEN (encoding phosphatase and tensin homolog) and the activity of the phosphoinositol-3 kinase (PI3K)-AKT signaling pathway in normal and leukemic T cells. Notch signaling and the PI3K-AKT pathway synergize in vivo in a Drosophila melanogaster model of Notch-induced tumorigenesis, and mutational loss of PTEN is associated with human T-ALL resistance to pharmacological inhibition of NOTCH1. Overall, these findings identify transcriptional control of PTEN and regulation of the PI3K-AKT pathway as key elements of the leukemogenic program activated by NOTCH1 and provide the basis for the design of new therapeutic strategies for T-ALL.

Changes in microRNA expression levels correlate with clinicopathological features and prognoses in endometrial serous adenocarcinomas

This study aimed to determine the expression profiles of microRNAs (miRNAs) in endometrial serous adenocarcinoma and to examine the association between miRNA expression and clinical outcomes. Twenty‐one patients diagnosed with endometrial serous adenocarcinoma between January 2001 and December 2006 were enrolled. miRNA expression profiles were examined using miRNA microarray and qRT‐PCR. miRNA expression levels were correlated with clinicopathological variables and survival rates. A total of 120 miRNAs were differentially expressed in endometrial serous adenocarcinoma compared to normal endometria. Of these, 54 miRNAs were down‐regulated (>2‐fold), including miR‐101, miR‐10b*, miR‐152, and miR‐29b, and the remainder were up‐regulated (>2‐fold), including miR‐200a, miR‐200b, and miR‐205. Decreased expression of miR‐10b*, miR‐29b, and miR‐455‐5p was correlated with vascular invasion (P = 0.048, P = 0.013, and P = 0.032, respectively). Univariate analysis revealed that lower expression of miR‐101, miR‐10b*, miR‐139‐5p, miR‐152, miR‐29b, and miR‐455‐5p was significantly correlated with poor overall survival (P < 0.05), and reduced expression of miR‐152, miR‐29b, and miR‐455‐5p was significantly correlated with poor disease‐free survival (P < 0.05). Multivariate analysis demonstrated that decreased expression of miR‐152 (P = 0.021) was a statistically independent risk factor for overall survival, and decreased expression levels of miR‐101 (P = 0.016) and miR‐152 (P = 0.010) were statistically independent risk factors for disease‐free survival. In addition, transfection of miR‐101 or miR‐152 precursors into an endometrial serous carcinoma cell line inhibited cell growth (P < 0.0001 and P = 0.01, respectively). Moreover, strong positive immunoreactivity of cyclooxygenase‐2 (COX‐2) was significantly correlated with down‐regulation of miR‐101 (P = 0.035). These findings suggest that the dysregulation of miRNAs is associated with the poor prognosis in endometrial serous adenocarcinoma patients. (Cancer Sci 2009)

BAF180 Is a Critical Regulator of p21 Induction and a Tumor Suppressor Mutated in Breast Cancer

Screening for tumor suppressor genes in breast cancer revealed multiple truncating mutations of PB1, which encodes the BAF180 subunit of the PBAF chromatin remodeling complex. Mutation was associated with loss of heterozygosity of the wild-type allele. BAF180 complementation of BAF180-mutant tumor cells caused G(1) arrest that was dependent on increased expression of the cyclin/cyclin-dependent kinase inhibitor p21/WAF1/CIP1. Endogenous wild-type BAF180 bound to the p21 promoter and was required for proper p21 expression and G(1) arrest after transforming growth factor-beta and gamma-radiation treatment. BAF180 thus functions on two tumor suppressor signaling pathways as a physiologic mediator of p21 expression. We conclude that BAF180 suppresses tumorigenesis, at least in part, through its ability to regulate p21.

PCDH8, the human homolog of PAPC, is a candidate tumor suppressor of breast cancer

Carcinoma is an altered state of tissue differentiation in which epithelial cells no longer respond to cues that keep them in their proper position. A break down in these cues has disastrous consequences not only in cancer but also in embryonic development when cells of various lineages must organize into discrete entities to form a body plan. Paraxial protocadherin (PAPC) is an adhesion protein with six cadherin repeats that organizes the formation and polarity of developing cellular structures in frog, fish and mouse embryos. Here we show that protocadherin-8 (PCDH8), the human ortholog of PAPC, is inactivated through either mutation or epigenetic silencing in a high fraction of breast carcinomas. Loss of PCDH8 expression is associated with loss of heterozygosity, partial promoter methylation, and increased proliferation. Complementation of mutant tumor cell line HCC2218 with wild-type PCDH8 inhibited its growth. Two tumor mutants, E146K and R343H, were defective for inhibition of cell growth and migration. Surprisingly, the E146K mutant transformed the human mammary epithelial cell line MCF10A and sustained the expression of cyclin D1 and MYC without epidermal growth factor. We propose that loss of PCDH8 promotes oncogenesis in epithelial human cancers by disrupting cell–cell communication dedicated to tissue organization and repression of mitogenic signaling.

Expression of vasohibin as a novel endothelium-derived angiogenesis inhibitor in endometrial cancer

We have previously reported on vasohibin as a novel endothelium‐derived vascular endothelial growth factor (VEGF)–inducible inhibitor of angiogenesis. The aim of our present study was to define the role of vasohibin in endometrioid endometrial adenocarcinoma. We collected 78 sections of endometrial carcinoma for assessment using immunohistochemistry. Twenty‐seven were well differentiated (G1), 25 were moderately differentiated (G2), and 26 were poorly differentiated endometrioid adenocarcinomas (G3). We also included 12 sections of normal cyclic endometria, six of which were in the proliferative phase and six were in the secretory phase. We investigated the expression of vasohibin, and compared it to VEGF receptor‐2 (VEGFR‐2: KDR/flk‐1), CD34, Ki‐67, VEGF‐A, and D2‐40 (as a lymphatic vessel marker). We assessed the ratio of vasohibin‐ and VEGFR‐2‐positive vessels in the stroma of endometrial carcinoma. Immunohistochemical assessment was classified as negative or positive based on staining intensity. Vasohibin was selectively expressed on vascular endothelial cells in both cyclic endometria and endometrial carcinomas. Vasohibin was highly expressed in the normal functional endmetrium of the secretory phase, especially in the spiral artery, and was highly expressed in all grades of endometrioid adenocarcinomas. The stromal endothelial cells in G3 expressed vasohibin and VEGFR‐2 more frequently than these in G1. In endometrioid adenocarcinomas, there was a significant correlation between the expression percentage of vasohibin and that of VEGFR‐2 (P < 0.0001, r2 = 0.591). This is the first study to elucidate the correlation between expression of vasohibin in the stromal endothelial cells and that of VEGFR‐2 in human carcinomas. (Cancer Sci 2008; 99: 914–919)

Deletion mapping on chromosome 10q25-q26 in human endometrial cancer.

To understand genetic events which play a role in the development and/or progression of human endometrial cancer, we studied allelotypes on all autosomal chromosomes, as well as chromosome X, with 42 microsatellite markers and 56 endometrial cancers. The most frequent loss of heterozygosity (LOH) was observed on the long arm of chromosome 10 (14 of 30, 47%), which was commonly detected in grade 1 cancer. We constructed a detailed deletion map and defined two commonly deleted regions in 10q25-q26; one was the 8 cM region between D10S209 and D10S216, the other was the 12 cM region between D10S217 and D10S590. Replication errors at two or more loci were observed in 24 of 56 tumours (43%), suggesting that disruption of the DNA mismatch repair system also plays an important role in the course of endometrial carcinogenesis.

Frequent gains on chromosome arms 1q and/or 8q in human endometrial cancer

Abstract Comparative genomic hybridization (CGH) was employed to survey genomic regions with increased and decreased copy number of the DNA sequence in 15 endometrial cancers [10 cases with microsatellite instability positive (MI+) and 5 cases with MI–]. Twelve of these 15 tumors (80%) showed abnormalities in copy number at one or more of the chromosomal regions. There were no regions with frequent chromosomal losses. Conversely, 11 of 15 cases (73%) showed gains on chromosome arms 1q (8/15; 53%) and/or 8q (6/15; 40%). Concordant gains of both chromosome arms 1q and 8q were observed in all three endometrial cancers of histological grade 3. These results suggest that these two chromosomal regions may contain genes whose increased expression contributes to development and/or progression of endometrial carcinogenesis. Two cases were further analyzed by fluorescence in situ hybridization (FISH) using three probes on chromosome 1 and two probes on chromosome 8 to more accurately determine increases in copy number. We found gains of chromosome 1q to 2.9–3.6 copies per cell and on 8q to 4.4 copies per cell.

MicroRNA-34b functions as a potential tumor suppressor in endometrial serous adenocarcinoma

Endometrial serous adenocarcinoma (ESC) is aggressive and carries a poor prognosis. p53 is frequently mutated in ESC. microRNAs (miRNAs) are a direct p53 target and have been implicated in cancer cell behavior. In this study, we compared miRNA expression levels in ESC with the levels in endometrial endometrioid adenocarcinoma (EEC) and normal endometria. Six miRNAs were identified as having aberrant down‐regulation specific to ESC with miR‐34b being most pronounced. miR‐34b was found to have promoter hypermethylation, which when reversed, restored miR‐34b expression in the cell lines treated with 5‐aza‐2′ deoxycytidine (DAC). Ectopic expression of miR‐34b in turn inhibited cell growth, migration and most notably invasion. Our findings suggest a relationship among p53 mutation, miR‐34b promoter methylation and tumor cell behavior. These effects are likely mediated by the downstream target of miR‐34b, the proto‐oncogene mesenchymal‐epithelial transition factor (MET), a known prognostic factor in endometrial carcinomas. The expression of MET was reduced following the restoration of miR‐34b in cell lines. In summary, our data suggest that miR‐34b plays a role in the molecular pathogenesis of endometrial cancer.

Evidence-based guidelines for treatment of cervical cancer in Japan: Japan Society of Gynecologic Oncology (JSGO) 2007 edition

Clinical practice guidelines for gynecologic cancers have been published by the National Comprehensive Cancer Network and the National Cancer Institute. Whereas these guidelines form the basis for the standard of care for gynecologic malignancies in the United States, it has proven difficult to institute them in Japan due to differences in patient characteristics, health-care delivery systems, and insurance programs. Therefore, evidence-based guidelines for treating cervical cancer specifically in Japan have been under development. The Guidelines Formulation Committee and Evaluation Committee were independently established within the Committee for Treatment Guidelines for Cervical Cancer. Opinions from within and outside the Japan Society of Gynecologic Oncology (JSGO) were incorporated into the final draft, and the guidelines were published after approval by the JSGO. These guidelines are composed of ten chapters and comprise three algorithms. Each chapter consists of a clinical question, recommendations, background, objectives, explanations, and references. The objective of these guidelines is to clearly delineate the standard of care for cervical cancer treatment in Japan in order to ensure equitable care for all Japanese women diagnosed with cervical cancer.

Progesterone receptor isoforms as a prognostic marker in human endometrial carcinoma

The possible role of specific progesterone receptor (PR) isoforms (PRA and PRB) as predictive factors in endometrial carcinoma is unclear. The present study was undertaken to evaluate the clinical significance of intratumoral PR isoform status in patients with endometrioid endometrial carcinoma. We studied 103 cases of endometrioid endometrial carcinoma using immunohistochemistry. We correlated the findings with various clinicopathological parameters of the patients. PRA and PRB immunoreactivity was detected in 51/103 (48.5%) and 79/103 (76.7%) of carcinoma cases, respectively. A significant positive correlation was detected between the status of PRB immunoreactivity and the amount of PRB mRNA by real‐time reverse transcription–polymerase chain reaction (P = 0.012). PR isoform expression was significantly lower in the cases with higher histological grade (P = 0.0001 and P = 0.002, for PRA and PRB, respectively). Cases that were negative for either one or both PR isoforms were significantly associated with shorter disease‐free and overall survival of the patients. The absence of either one or both of these two PR isoforms was detected in all nine patients who died (100.0%), whereas the absence of these immunoreactivities was detected only in 43 of 94 (45.7%) patients who had lived during the same period. In addition, multivariate analysis demonstrated that an absence of PRA immunoreactivity was an independent risk factor in disease‐free survival of the patients (P = 0.0258). The results of our study demonstrated that loss or absence of PR isoform expression determined by immunohistochemistry could become an important prognostic indicator in patients with endometrioid endometrial carcinoma. (Cancer Sci 2006; 97: 1308–1314)