The changes in DNA methylation status in cancer cells are characterized by hypermethylation of promoter CpG islands and diffuse genomic hypomethylation. Alu and long interspersed nucleotide element-1 (LINE-1) are non-coding genomic repetitive sequences and methylation of these elements can be used as a surrogate marker for genome-wide methylation status. This study was designed to evaluate the changes of Alu and LINE-1 hypomethylation during breast cancer progression from normal to pre-invasive lesions and invasive breast cancer (IBC), and their relationship with characteristics of IBC. We analyzed the methylation status of Alu and LINE-1 in 145 cases of breast samples including normal breast tissue, atypical ductal hyperplasia/flat epithelial atypia (ADH/FEA), ductal carcinoma in situ (DCIS) and IBC, and another set of 129 cases of IBC by pyrosequencing. Alu methylation showed no significant changes during multistep progression of breast cancer, although it tended to decrease during the transition from DCIS to IBC. In contrast, LINE-1 methylation significantly decreased from normal to ADH/FEA, while it was similar in ADH/FEA, DCIS and IBC. In IBC, Alu hypomethylation correlated with negative estrogen receptor (ER) status, and LINE-1 hypomethylation was associated with negative ER status, ERBB2 (HER2) amplification and p53 overexpression. Alu and LINE-1 methylation status was significantly different between breast cancer subtypes, and the HER2 enriched subtype had lowest methylation levels. In survival analyses, low Alu methylation status tended to be associated with poor disease-free survival of the patients. Our findings suggest that LINE-1 hypomethylation is an early event and Alu hypomethylation is probably a late event during breast cancer progression, and prominent hypomethylation of Alu and LINE-1 in HER2 enriched subtype may be related to chromosomal instability of this specific subtype.

The epithelial-to-mesenchymal transition (EMT) process allows carcinoma cells to dissociate from the primary tumor thereby facilitating tumor cell invasion and metastasis. Ras-dependent hyperactive signaling is commonly associated with tumorigenesis, invasion, EMT, and metastasis. However, the downstream effectors by which Ras regulates EMT remain ill defined. In this study, we show that the H-Ras pathway leads to mesenchymal-like phenotypic changes in human breast epithelial cells by controlling the ZEB1/microRNA–200c axis. Moreover, H-Ras suppresses the expression of the discoidin domain receptor 1 (DDR1), a collagen receptor tyrosine kinase, via ZEB1, thus identifying ZEB1 as a novel transcriptional repressor of DDR1. Mutation studies on the putative promoter of the DDR1 gene revealed that bipartite Z- and E-box elements play a key role in transcriptional repression of DDR1 in Hs578T and MDA-MB-231 breast carcinoma cell lines by ZEB1. Furthermore, we found an inverse correlation between ZEB1 and DDR1 expression in various cancer cell lines and in human breast carcinoma tissues. Consistently, overexpression of DDR1 reduced the invasive phenotype of mesenchymal-like triple-negative breast cancer cells in 3D cultures and in vivo. Thus, ZEB1’s role in maintenance of EMT in breast carcinoma cells is mediated in part by its ability to suppress DDR1 expression and consequently contribute to the activation of the invasive phenotype. Taken together, our results unveil a novel H-Ras/ZEB1/DDR1 network that contributes to breast cancer progression in triple-negative breast cancers.

PurposeSomatic mutations of the chromatin remodeling AT-rich interactive domain 1A (SWI-like) gene (ARID1A) have been identified in many human cancers, including breast cancer. The purpose of this study was to evaluate the nuclear expression of ARID1A in breast cancers by immunohistochemistry (IHC) and to correlate the findings to clinicopathologic variables including prognostic significance.MethodsIHC was performed on tissue microarrays of 476 cases of breast cancer. Associations between ARID1A expression and clinicopathologic characteristics and molecular subtype were retrospectively analyzed.ResultsLow expression of ARID1A was found in 339 of 476 (71.2%) cases. Low expression of ARID1A significantly correlated with positive lymph node metastasis (p=0.027), advanced pathologic stage (p=0.001), low Ki-67 labeling index (p=0.003), and negative p53 expression (p=0.017). The ARID1A low expression group had significantly shorter disease-free and overall survival than the ARID1A high expression group (p<0.001 and p<0.001, respectively). Multivariate analysis demonstrated that low expression of ARID1A was a significant independent predictive factor for poor disease-free and overall survival in patients with breast cancer (disease-free survival: hazard ratio, 0.38, 95% confidence interval [CI], 0.20-0.73, p=0.004; overall survival: hazard ratio, 0.11, 95% CI, 0.03-0.46, p=0.003). In patients with luminal A type disease, patients with low ARID1A expression had significantly shorter disease-free and overall survival rates than patients with high ARID1A expression (p=0.022 and p=0.018, respectively).ConclusionLow expression of ARID1A is an independent prognostic factor for disease-free and overall survival in breast cancer patients and may be associated with luminal A type disease. Although the biologic function of ARID1A in breast cancer remains unknown, low expression of ARID1A can provide valuable prognostic information.

PurposeThe AT-rich interactive domain 1A (ARID1A) gene encodes BRG1-associated factor 250a, a component of the SWItch/Sucrose NonFermentable chromatin remodeling complex, which is considered a tumor suppressor in many tumors. We aimed to investigate the prognostic significance of ARID1A expression in gastric cancers and explore its relationship with clinicopathologic parameters such as mismatch repair protein expression.Materials and MethodsFour tissue microarrays were constructed from 191 resected specimens obtained at Soonchunhyang University Cheonan Hospital from 2006 to 2008. Nuclear expression of ARID1A was semiquantitatively assessed and binarized into retained and lost expression.ResultsLoss of ARID1A expression was observed in 62 cases (32.5%). This was associated with more frequent vascular invasion (P=0.019) and location in the upper third of the stomach (P=0.001), and trended toward more poorly differentiated subtypes (P=0.054). ARID1A loss was significantly associated with the mismatch repair-deficient phenotype (P=0.003). ARID1A loss showed a statistically significant correlation with loss of MLH1 (P=0.001) but not MSH2 expression (P=1.000). Kaplan-Meier survival analysis showed no statistically significant difference in overall survival; however, patients with retained ARID1A expression tended to have better overall survival than those with loss of ARID1A expression (P=0.053). In both mismatch repair-deficient and mismatch repair-proficient groups, survival analysis showed no differences related to ARID1A expression status.ConclusionsOur results demonstrated that loss of ARID1A expression is closely associated with the mismatch repair-deficient phenotype, especially in sporadic microsatellite instability-high gastric cancers.

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A glomus tumor in the mediastinum is very uncommon, and only five cases have been reported in the English literature. We recently encountered a 21-year-old woman with an asymptomatic mediastinal mass that measured 5.3 × 4.0 cm. Surgical excision was performed, and the tumor was finally diagnosed as mediastinal glomus tumor with an uncertain malignant potential. After reviewing this case and previous reports, we analyzed the clinicopathologic features associated with progression of such a tumor.

BackgroundThe Hippo pathway plays a vital role in liver regeneration and development by determining cellular lineage and regulating cell proliferation and apoptosis. In this study, we aimed to assess the role of the Hippo pathway in hepatic carcinogenesis and morphogenesis by examining Yes-associated protein 1 (YAP1) expression in the spectrum of hepatic carcinomas based on cellular lineage.MethodsWe examined 913 primary hepatic carcinomas, including hepatocellular carcinomas (HCCs), combined hepatocellular and cholangiocarcinomas (cHC-CCAs), intrahepatic cholangiocarcinomas (IHCCAs) and perihilar extrahepatic bile duct carcinomas (EHBCAs). Our study group was categorized into 8 disease groups, based on histological diagnosis and cytokeratin 19 (CK19) expression, and immunohistochemistry was used to detect and compare YAP1 expression levels between the groups. The eight disease groups we identified were: 1) CK19(−) HCC, 2) CK19(−) scirrhous HCC, 3) CK19(+) HCC, 4) stem cell feature of cHC-CCA, 5) classical cHC-CCA, 6) cholangiolocellular IHCCA, 7) non-cholangiolocellular IHCCA, and 8) EHBCA.ResultsPositive rates of YAP1 were the highest in the EHBCA group (21%). CK19(+) HCC and non-cholangiolocellular IHCCA groups also showed high expression levels (10% -11%), while the CK19 (−) HCC, CK19 (−) scirrhous HCC, cHC-CCA, and cholangiolocellular IHCCA groups showed low expression levels, ranging between 0% and 5%. Survival analysis, restricted to pT1 stage HCCs and IHCCAs, showed poor overall survival for YAP1(+) IHCCA patients (39 ± 17 vs. 109 ± 10 months, mean ± SD, log rank p-value 0.005). For HCCs, a trend of poor progression-free survival for YAP1(+) HCCs was observed (39 ± 18 vs. 81 ± 5 months, mean ± SD, log rank p-value 0.205)ConclusionsYAP1 activation was more commonly found in CCAs than in pure HCCs. However, a differing pattern of YAP1 expression between cHC-CCAs and CK19(+) HCCs and the poor prognosis of YAP1 positive hepatic carcinomas suggests that YAP1 may have a preferential role in aggressive tumor behavior, rather than in the determination of cellular lineage in hepatic carcinomas.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-017-3431-1) contains supplementary material, which is available to authorized users.

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