Comparative study between DNA copy number aberrations determined by quantitative microsatellite analysis and clinical outcome in patients with stomach cancer

The dark side of ZNF217, a key regulator of tumorigenesis with powerful biomarker value

The recently described oncogene ZNF217 belongs to a chromosomal region that is frequently amplified in human cancers. Recent findings have revealed that alternative mechanisms such as epigenetic regulation also govern the expression of the encoded ZNF217 protein. Newly discovered molecular functions of ZNF217 indicate that it orchestrates complex intracellular circuits as a new key regulator of tumorigenesis. In this review, we focus on recent research on ZNF217-driven molecular functions in human cancers, revisiting major hallmarks of cancer and highlighting the downstream molecular targets and signaling pathways of ZNF217. We also discuss the exciting translational medicine investigating ZNF217 expression levels as a new powerful biomarker, and ZNF217 as a candidate target for future anti-cancer therapies.

Genomic amplification upregulates estrogen-related receptor alpha and its depletion inhibits oral squamous cell carcinoma tumors in vivo

The ESRRA gene encodes a transcription factor and regulates several genes, such as WNT11 and OPN, involved in tumorigenesis. It is upregulated in several cancers, including OSCC. We have previously shown that the tumor suppressor miR-125a targets ESRRA, and its downregulation causes upregulation of ESRRA in OSCC. Upregulation of ESRRA in the absence of downregulation of miR-125a in a subset of OSCC samples suggests the involvement of an alternative mechanism. Using TaqMan(®) copy number assay, here we report for the first time that the genomic amplification of ESRRA causes its upregulation in a subset of OSCC samples. Ectopic overexpression of ESRRA led to accelerated cell proliferation, anchorage-independent cell growth and invasion, and inhibited apoptosis. Whereas, knockdown of ESRRA expression by siRNA led to reduced cell proliferation, anchorage-independent cell growth and invasion, and accelerated apoptosis. Furthermore, the delivery of a synthetic biostable ESRRA siRNA to OSCC cells resulted in regression of xenografts in nude mice. Thus, the genomic amplification of ESRRA is another novel mechanism for its upregulation in OSCC. Based on our in vitro and in vivo experiments, we suggest that targeting ESRRA by siRNA could be a novel therapeutic strategy for OSCC and other cancers.

Is microsatellite instability a prognostic marker in gastric cancer? A systematic review with meta-analysis

BACKGROUND AND OBJECTIVE

The relationship between survival in gastric cancer patients and the status of microsatellite instability (MSI) has not yet been established. The purpose of this meta-analysis was to obtain integrated and more precise data for the value of MSI as a prognostic marker in gastric cancer.

METHODS

A comprehensive systematic review and meta-analysis were conducted using major electronic databases (PubMed, EMBASE, and the Cochrane Central) with keywords related to "microsatellite instability," "gastric cancer," and "prognosis."

RESULTS

Twenty-four studies with 5,438 participants (712 cases were MSI gastric cancer) were included for pooling risk estimates of MSI in gastric cancer. Seventeen studies reported overall survival. The pooled hazard ratio (HR) for overall survival of MSI vs. non-MSI was 0.72 (95%CI: 0.59-0.88, P = .001) in a random-effects model. In the sensitivity analysis, the result from the most recent study showed the most heterogeneity.

CONCLUSION

MSI gastric cancer was associated with good prognosis but there was heterogeneity in the recent studies. Changed epidemiology and effects of chemotherapy are potential causes of heterogeneity. Establishing a consensus for defining MSI in gastric cancer should be preferred for future studies.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

Clinical aspect and molecular mechanism of DNA aneuploidy in gastric cancers

The biological characteristics of cancers depend mostly on genetic alterations in the cancer cells of individuals. Gastric cancers show a high frequency of DNA aneuploidy, a phenotype of chromosomal instability. Compared to diploid tumors, gastric carcinomas with aneuploidy have been shown to have high proliferative activity and high metastatic or invasive potential; these characteristics lead to a poor prognosis. It has been suggested that an abnormal spindle assembly checkpoint is involved in DNA aneuploidy, but the underlying mechanism is still unclear. This review, in order to determine whether gastric carcinomas that display aneuploidy are associated with a poorer prognosis than diploid tumors, and to discuss the biological mechanisms that induce aneuploidy, summarizes the results of studies on DNA ploidy in gastric cancer published in the English literature. Analysis of DNA ploidy in gastric cancer may provide clinically useful information from diagnostic, therapeutic, and prognostic standpoints. Further investigations may be needed to clarify the relationship between chromosome instability and DNA ploidy.

Down-regulation of tyrosine aminotransferase at a frequently deleted region 16q22 contributes to the pathogenesis of hepatocellular carcinoma

Loss of 16q is one of the most frequent alterations in many malignancies including hepatocellular carcinomas (HCC), suggesting the existence of a tumor suppressor gene (TSG) within the frequently deleted region. In this report we describe the identification and characterization of one candidate TSG, tyrosine aminotransferase gene (TAT), at 16q22.1. Loss of one TAT allele was detected in 27/50 (54%) of primary HCCs by quantitative real-time polymerase chain reaction. In addition, homo-deletion of TAT alleles was detected in two cases. Down-regulation of TAT was detected in 28/50 (56%) of HCCs, which was significantly associated with the loss of TAT allele and hypermethylation of TAT 5' CpG island (CGI) region (P < 0.001). Functional studies found that TAT has a strong tumor suppressive ability. Introduction of the TAT gene into HCC cell lines could effectively inhibit colony formation in soft agar, foci formation, and tumor formation in nude mice. Further study found that the tumor suppressive mechanism of TAT was associated with its proapoptotic role in a mitochondrial-dependent manner by promoting cytochrome-c release and activating caspase-9 and PARP.

CONCLUSION

Taken together, our findings suggest that TAT plays an important suppressive role in the development and progression of HCC.

DNA copy numbers profiles in affinity-purified ovarian clear cell carcinoma

PURPOSE

Advanced ovarian clear cell carcinoma (CCC) is one of the most aggressive ovarian malignancies, in part because it tends to be resistant to platinum-based chemotherapy. At present, little is known about the molecular genetic alterations in CCCs except that there are frequent activating mutations in PIK3CA. The purpose of this study is to comprehensively define the genomic changes in CCC based on DNA copy number alterations.

EXPERIMENTAL DESIGN

We performed 250K high-density single nucleotide polymorphism array analysis in 12 affinity-purified CCCs and 10 CCC cell lines. Discrete regions of amplification and deletion were also analyzed in additional 21 affinity-purified CCCs using quantitative real-time PCR.

RESULTS

The level of chromosomal instability in CCC as defined by the extent of DNA copy number changes is similar to those previously reported in low-grade ovarian serous carcinoma but much less than those in high-grade serous carcinoma. The most remarkable region with DNA copy number gain is at chr20, which harbors a potential oncogene, ZNF217. This discrete amplicon is observed in 36% of CCCs but rarely detected in serous carcinomas regardless of grade. In addition, homozygous deletions are detected at the CDKN2A/2B and LZTS1 loci. Interestingly, the DNA copy number changes observed in fresh CCC tissues are rarely detected in the established CCC cell lines.

CONCLUSIONS

This study provides the first high resolution, genome-wide view of DNA copy number alterations in ovarian CCC. The findings provide a genomic landscape for future studies aimed at elucidating the pathogenesis and developing new target-based therapies for CCCs.

Genome analysis identifies the p15ink4b tumor suppressor as a direct target of the ZNF217/CoREST complex

The ZNF217 oncoprotein is a constituent of a core transcriptional complex that includes CoREST, histone deacetylase 1/2, lysine demethylase 1, and the C-terminal binding protein 1/2. We have combined genome-wide expression profiling and chromatin immunoprecipitation with directed selection and ligation (ChIP-DSL) to identify a subset of genes directly regulated by ZNF217. Our results establish p15(ink4b) as a direct target of the ZNF217 complex. Downregulation of ZNF217 in MCF-7 breast cancer cells resulted in a dramatic increase in p15(ink4b) expression and coincided with increases in dimethylation of H3-K4 and, surprisingly, a decrease in K9/K14-H3 acetylation. Stimulation of HaCaT cells with transforming growth factor beta (TGF-beta) resulted in a release of ZNF217 and a concomitant binding of SMAD2 to the proximal promoter, which preceded increases in ink4b protein expression. Furthermore, the changes in chromatin marks at the p15(ink4b) promoter following TGF-beta stimulation were similar to those observed following ZNF217 downregulation. Collectively, these results establish the ZNF217 complex as a novel negative regulator of the p15(ink4b) gene and may constitute an important link between amplification of ZNF217 and the loss of TGF-beta responsiveness in breast cancer.

Cytogenetic and molecular aspects of gastric cancer: clinical implications

Gastric cancer is of major importance world-wide being the second most common cause of cancer-related death in the world. According to Lauren's histological classification gastric cancer is divided in two groups, the better differentiated intestinal carcinomas and the poorly differentiated diffuse-type cancers. The genetic changes underlying the initiation and progression of gastric cancer are not well defined. Gastric carcinogenesis is a multistep process involving a number of genetic and epigenetic factors. Although it has been proposed that different genetic pathways exist for differentiated and undifferentiated carcinomas, the two histological subtypes of gastric cancer share some common genetic alterations. Currently, tumor histology and pathologic stage are the major prognostic variables used in the clinical practice for gastric cancer patients. However, it is known that tumors with similar morphology may differ in biological aggressiveness, prognosis and response to treatment. Molecular genetic analysis of gastric cancer revealed a number of associations of certain genetic changes with pathological features, tumor biological behavior and prognosis of gastric cancer patients, suggesting that these genetic abnormalities might play an important role in gastric tumorigenesis. Increasing evidence suggests that the molecular genetic changes could be helpful in the clinical setting, contributing to prognosis and management of patients. Regarding epigenetic events in gastric tumorigenesis, a number of methylating markers have been proposed for risk assessment, prognostic evaluation and as therapeutic targets. However, further research is required in order to systematically investigate the genetic changes in gastric cancer estimating also their usefulness in the clinical practice. A good understanding of the genetic changes underlying gastric carcinogenesis may provide new perspectives for prognosis and screening of high risk individuals. Some of the genetic alterations could definitely improve tumor classification and management of gastric cancer patients. Also, based on molecular data identified in gastric cancer novel therapeutics might help to improve the treatment of this disease.

Amplification of D22S283 as a favorable prognostic indicator in liver fluke related cholangiocarcinoma

AIM: To analyze the DNA copy number of target genes NF2, TIMP3, ST13, TOB2, BIK, and TP and the reference microsatellite markers D22S283, D22S423, and D22S274 mapped on 22q12-qter in liver fluke related cholangiocarcinoma (CCA) and define its correlation with clinical parameters.

METHODS: Quantitative real time PCR (qPCR) was used for determining allelic imbalances in 65 liver fluke related CCA tissues. Statistical correlations between allelic imbalances and clinicopathological parameters, i.e. age, sex, tumor stage, histological type, blood vessel invasion, nerve invasion and lymphatic invasion were evaluated by means of the χ² test. Cox regression analysis was used for determining patient’s survival.

RESULTS: Amplifications of the TP (22q13.33), TOB2 (22q13.2-13.31), D22S283 (22q12.3), TIMP3 (22q12.3) and NF2 (22q12.2) were found in 35 (53.8%), 28 (43.1%), 27 (41.5%), 24 (36.9%), and 24 (36.9%), respectively. Losses at the D22S423 (22q13.1-13.2) and BIK (22q13.31) were detected in 26 (40%) and 23 (35.4%), respectively. Significant correlations were observed between lymphatic invasion and allelic losses of BIK (P = 0.025) and D22S283 (P = 0.041). Univariate and multivariate Cox regression analysis revealed D22S283 amplification as an independent predictor of good prognosis (P = 0.006, death hazard ratio = 0.411, 95% CI = 0.217-0.779) and blood vessel invasion as an independent poor prognostic factor (P = 0.042, death hazard ratio = 1.911, 95% CI = 1.022-3.571) in CCA patients.

CONCLUSION: This study provides evidence for the involvement of gene amplification and deletion on chromosome 22q in liver fluke related CCA. This is the first report of D22S283 amplification as an independent indicator of favorable prognosis in liver fluke related CCA.

Plasminogen activator inhibitor-1 as a potential marker for the malignancy of gastric cancer

To test the hypothesis that plasminogen activator inhibitor-1 (PAI-1) may serve as a candidate marker for the malignancy of gastric cancer, we carried out quantitative reverse transcription-polymerase chain reaction for the PAI-1 gene and evaluated the possible relationship between PAI-1 gene expression levels and clinicopathological findings in gastric cancer. A significant increase in PAI-1 expression scores was observed in lymph node metastasis-positive gastric cancers (2.11 +/- 0.35) compared to metastasis-negative cancers (0.33 +/- 0.49) (P = 0.0048), as well as in distant metastasis-positive gastric cancers (3.68 +/- 0.58) compared to metastasis-negative cancers (1.20 +/- 0.32). The PAI-1 expression score markedly increased with tumor stage (P < 0.0001; ANOVA test). Moreover, multivariate analysis revealed the PAI-1 expression score to be a strong and independent prognostic factor for gastric cancer (P = 0.0450). These results suggested that PAI-1 might serve as a new and promising parameter for the prediction of prognosis in gastric cancer.