Aya Shinozaki-Ushiku

Update on Epstein-Barr virus and gastric cancer (review).

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) is a distinct subtype that accounts for nearly 10% of gastric carcinomas. EBVaGC is defined by monoclonal proliferation of carcinoma cells with latent EBV infection, as demonstrated by EBV-encoded small RNA (EBER) in situ hybridization. EBVaGC has characteristic clinicopathological features, including predominance among males, a proximal location in the stomach, lymphoepithelioma-like histology and a favorable prognosis. EBVaGC belongs to latency type I or II, in which EBERs, EBNA-1, BARTs, LMP-2A and BART miRNAs are expressed. Previous studies have shown that some EBV latent genes have oncogenic properties. Recent advances in genome-wide and comprehensive molecular analyses have demonstrated that both genetic and epigenetic changes contribute to EBVaGC carcinogenesis. Genetic changes that are characteristic of EBVaGC include frequent mutations in PIK3CA and ARID1A and amplification of JAK2 and PD-L1/L2. Global CpG island hypermethylation, which induces epigenetic silencing of tumor suppressor genes, is also a unique feature of EBVaGC and is considered to be crucial for its carcinogenesis. Furthermore, post-transcriptional gene expression regulation by cellular and/or EBV-derived microRNAs has attracted considerable attention. These abnormalities result in significant alterations in gene expression related to cell proliferation, apoptosis, migration and immune signaling pathways. In the present review we highlight the latest findings on EBVaGC from clinicopathological and molecular perspectives to provide a better understanding of EBV involvement in gastric carcinogenesis.

Epigenetic silencing of miR-210 increases the proliferation of gastric epithelium during chronic Helicobacter pylori infection

Persistent colonization of the gastric mucosa by Helicobacter pylori (Hp) elicits chronic inflammation and aberrant epithelial cell proliferation, which increases the risk of gastric cancer. Here we examine the ability of microRNAs to modulate gastric cell proliferation in response to persistent Hp infection and find that epigenetic silencing of miR-210 plays a key role in gastric disease progression. Importantly, DNA methylation of the miR-210 gene is increased in Hp-positive human gastric biopsies as compared with Hp-negative controls. Moreover, silencing of miR-210 in gastric epithelial cells promotes proliferation. We identify STMN1 and DIMT1 as miR-210 target genes and demonstrate that inhibition of miR-210 expression augments cell proliferation by activating STMN1 and DIMT1 . Together, our results highlight inflammation-induced epigenetic silencing of miR-210 as a mechanism of induction of chronic gastric diseases, including cancer, during Hp infection.

Profiling of Virus-encoded MicroRNAs in Epstein-Barr Virus-associated Gastric Carcinoma and their Roles in Gastric Carcinogenesis

ABSTRACT Epstein-Barr virus (EBV) is one of the major oncogenic viruses and is found in nearly 10% of gastric carcinomas. EBV is known to encode its own microRNAs (miRNAs); however, their roles have not been fully investigated. The present report is the largest series to comprehensively profile the expression of 44 known EBV miRNAs in tissue samples from patients with EBV-associated gastric carcinoma. Several miRNAs were highly expressed in EBV-associated gastric carcinoma, and in silico analysis revealed that the target genes of these EBV miRNAs had functions associated with cancer-related pathways, especially the regulation of apoptosis. Apoptosis was reduced in EBV-associated gastric carcinoma tissue samples, and gastric carcinoma cell lines infected with EBV exhibited downregulation of the proapoptotic protein Bid (the BH3-interacting domain death agonist), a member of the Bcl-2 family. The luciferase activity of the reporter vector containing the 3′ untranslated region of BID was inhibited by an ebv-miR-BART4-5p mimic in gastric cancer cell lines. Transfection of an ebv-miR-BART4-5p mimic reduced Bid expression in EBV-negative cell lines, leading to reduced apoptosis under serum deprivation. The inhibition of ebv-miR-BART4-5p expression was associated with partial recovery of Bid levels in EBV-positive cell lines. The results demonstrated the antiapoptotic role of EBV miRNA via regulation of Bid expression in EBV-associated gastric carcinoma. These findings provide novel insights in the roles of EBV miRNAs in gastric carcinogenesis, which would be a potential therapeutic target. IMPORTANCE This report is the largest series to comprehensively profile the expression of 44 known EBV miRNAs in clinical samples from EBV-associated gastric carcinoma patients. Of the EBV miRNAs, ebv-miR-BART4-5p plays an important role in gastric carcinogenesis via regulation of apoptosis.

EZH2 promotes progression of small cell lung cancer by suppressing the TGF-β-Smad-ASCL1 pathway

Transforming growth factor-β (TGF-β) induces apoptosis in many types of cancer cells and acts as a tumor suppressor. We performed a functional analysis of TGF-β signaling to identify a molecular mechanism that regulated survival in small cell lung cancer cells. Here, we found low expression of TGF-β type II receptor (TβRII) in most small cell lung cancer cells and tissues compared to normal lung epithelial cells and normal lung tissues, respectively. When wild-type TβRII was overexpressed in small cell lung cancer cells, TGF-β suppressed cell growth in vitro and tumor formation in vivo through induction of apoptosis. Components of polycomb repressive complex 2, including enhancer of zeste 2 (EZH2), were highly expressed in small cell lung cancer cells; this led to epigenetic silencing of TβRII expression and suppression of TGF-β-mediated apoptosis. Achaete-scute family bHLH transcription factor 1 (ASCL1; also known as ASH1), a Smad-dependent target of TGF-β, was found to induce survival in small cell lung cancer cells. Thus, EZH2 promoted small cell lung cancer progression by suppressing the TGF-β-Smad-ASCL1 pathway.

Distinct expression pattern of claudin‐6, a primitive phenotypic tight junction molecule, in germ cell tumours and visceral carcinomas

Ushiku T, Shinozaki‐Ushiku A, Maeda D, Morita S & Fukayama M 
(2012) Histopathology
Distinct expression pattern of claudin‐6, a primitive phenotypic tight junction molecule, in germ cell tumours and visceral carcinomas

Diagnostic utility of BAP1 and EZH2 expression in malignant mesothelioma.

Malignant mesothelioma is a highly aggressive cancer that is usually diagnosed at advanced stages; thus, highly sensitive and specific markers are necessary for its early definitive diagnosis. The aim of this study was to evaluate the diagnostic utility and prognostic significance of BAP1 and EZH2 in malignant mesothelioma.

Lipase member H is a novel secreted protein selectively upregulated in human lung adenocarcinomas and bronchioloalveolar carcinomas

Lung cancer is one of the most frequent causes of cancer-related death worldwide. However, molecular markers for lung cancer have not been well established. To identify novel genes related to lung cancer development, we surveyed publicly available DNA microarray data on lung cancer tissues. We identified lipase member H (LIPH, also known as mPA-PLA1) as one of the significantly upregulated genes in lung adenocarcinoma. LIPH was expressed in several adenocarcinoma cell lines when they were analyzed by quantitative real-time polymerase chain reaction (qPCR), western blotting, and sandwich enzyme-linked immunosorbent assay (ELISA). Immunohistochemical analysis detected LIPH expression in most of the adenocarcinomas and bronchioloalveolar carcinomas tissue sections obtained from lung cancer patients. LIPH expression was also observed less frequently in the squamous lung cancer tissue samples. Furthermore, LIPH protein was upregulated in the serum of early- and late-phase lung cancer patients when they were analyzed by ELISA. Interestingly, high serum level of LIPH was correlated with better survival in early phase lung cancer patients after surgery. Thus, LIPH may be a novel molecular biomarker for lung cancer, especially for adenocarcinoma and bronchioloalveolar carcinoma.

Nerve Growth Factor Signals as Possible Pathogenic Biomarkers for Perineural Invasion in Adenoid Cystic Carcinoma

Objective The molecular mechanisms underlying perineural invasion (PNI)—a characteristic pathological feature of adenoid cystic carcinoma (ACC)—remain largely unclear. Recently, nerve growth factor (NGF) has been implicated in perineural invasion in certain malignancies. Overexpression of Myb related to the MYB-NFIB fusion gene in ACC has also been correlated with perineural invasion and survival. However, this concept is controversial. The aim of this study was to examine the expression of NGF together with its receptors, tropomyosin receptor kinase A (TrkA) and p75NRT, and Myb in ACC and assess their relationship with perineural invasion and survival. Study Design Case series with chart review. Setting The University of Tokyo Hospital. Subjects and Methods We retrospectively analyzed 37 patients with ACC surgically treated from 1991 to 2011. We examined expression levels of NGF, TrkA, p75NRT, and Myb in the ACC specimens and their correlations with PNI and prognosis. Results NGF, TrkA, p75NRT, and Myb overexpression rates were 65%, 65%, 30%, and 62%, respectively. Pearson product-moment correlation coefficient revealed a strong correlation between NGF/TrkA immunostaining and PNI (NGF: r = 0.68, P < .0001; TrkA: r = 0.53, P = .0007). Moreover, NGF overexpression was significantly associated with worse 8-year local control rate (27% vs 80%, P = .005). However, p75NRT and Myb expression was related to neither perineural invasion nor survival. Conclusion Our findings demonstrated that NGF and TrkA overexpression, but not Myb and p75NRT overexpression, may contribute to PNI and thus cause local recurrence in patients with ACC.

Quantitative computed tomography texture analysis for estimating histological subtypes of thymic epithelial tumors

OBJECTIVES To investigate whether high-risk thymic epithelial tumor (TET) (HTET) can be differentiated from low-risk TET (LTET) using computed tomography (CT) quantitative texture analysis. MATERIALS AND METHODS The data of 39 patients (mean age, 58.6±14.1 years) (39 unenhanced CT (UECT) and 33 contrast-enhanced CT (CECT)) who underwent thymectomy for TET were retrospectively analyzed. A region of interest was placed to include the entire TET within the slice at its maximum diameter. Texture analysis was performed for images with or without a Laplacian of Gaussian filter (with various spatial scaling factors [SSFs]). Two radiologists evaluated the visual heterogeneity of TET using a 3-point scale. RESULTS The mean in the unfiltered image (mean0u) and entropy in the filtered image (SSF: 6mm) (entropy6u) for UECT, and the mean in the unfiltered image (mean0c) for CECT were significant parameters for differentiating between HTET and LTET as determined by logistic regression analysis. The area under the receiver operating characteristics curve (AUC) for differentiating HTET from LTET using mean0u, entropy6u, and mean0c was 0.75, 0.76, and 0.89, respectively. And the combination of mean0u and entropy6u allowed AUC of 0.87. Entropy6u provided a higher diagnostic performance compared with visual heterogeneity analysis (p≤0.018). CONCLUSION Using CT quantitative texture analysis, HTET can be differentiated from LTET with a high diagnostic performance.

Loss of YAP1 defines neuroendocrine differentiation of lung tumors

YAP1, the main Hippo pathway effector, is a potent oncogene and is overexpressed in non‐small‐cell lung cancer (NSCLC); however, the YAP1 expression pattern in small‐cell lung cancer (SCLC) has not yet been elucidated in detail. We report that the loss of YAP1 is a special feature of high‐grade neuroendocrine lung tumors. A hierarchical cluster analysis of 15 high‐grade neuroendocrine tumor cell lines containing 14 SCLC cell lines that depended on the genes of Hippo pathway molecules and neuroendocrine markers clearly classified these lines into two groups: the YAP1‐negative and neuroendocrine marker‐positive group (n = 11), and the YAP1‐positive and neuroendocrine marker‐negative group (n = 4). Among the 41 NSCLC cell lines examined, the loss of YAP1 was only observed in one cell line showing the strong expression of neuroendocrine markers. Immunostaining for YAP1, using the sections of 189 NSCLC, 41 SCLC, and 30 large cell neuroendocrine carcinoma (LCNEC) cases, revealed that the loss of YAP1 was common in SCLC (40/41, 98%) and LCNEC (18/30, 60%), but was rare in NSCLC (6/189, 3%). Among the SCLC and LCNEC cases tested, the loss of YAP1 correlated with the expression of neuroendocrine markers, and a survival analysis revealed that YAP1‐negative cases were more chemosensitive than YAP1‐positive cases. Chemosensitivity test for cisplatin using YAP1‐positive/YAP1‐negative SCLC cell lines also showed compatible results. YAP1‐sh‐mediated knockdown induced the neuroendocrine marker RAB3a, which suggested the possible involvement of YAP1 in the regulation of neuroendocrine differentiation. Thus, we showed that the loss of YAP1 has potential as a clinical marker for predicting neuroendocrine features and chemosensitivity.