Loss of Heterozygosity and Immunohistochemistry of Adenocarcinomas of the Esophagus and Gastric Cardia

Hub genes in adenocarcinoma of the esophagogastric junction based on weighted gene co-expression network analysis and immunohistochemistry

BACKGROUND

Gastric cancer (GC) is the fifth most common malignant tumor, and it is usually fatal. Adenocarcinoma of the esophagogastric junction (AEG) accounts for about 50% of all GC cases. However, the systematic co-expression analysis of this tumor does not fully explain its pathogenesis. This study aimed to identify hub genes based on weighted gene co-expression networks and immunohistochemistry analyses.

METHODS

The RNA-seq data of 22 AEG patients were processed using weighted gene co-expression network analysis. We differentiated the modules with clinical tumor markers and performed Gene Ontology and pathway enrichment analysis. We identified the hub genes related to the biological processes of tumorigenesis based on weighted gene co-expression network analysis and immunohistochemistry analysis.

RESULTS

Twenty-five distinct co-expression gene modules were identified; the tumorigenic genes CD93, TRIM28, SLC3A2, CBX4, PATL1, and ZNF473 had high intramodular connectivity. Immunohistochemistry confirmed that these hub genes are upregulated in AEG. Statistical analysis indicated that the expression of CD93 was correlated with the T stage and maximum tumor diameter.

CONCLUSION

Weighted gene co-expression network analysis and immunohistochemistry identified CD93 as a hub gene that might be critical for AEG biology.

Kyoto international consensus report on anatomy, pathophysiology and clinical significance of the gastro-oesophageal junction

OBJECTIVE

An international meeting was organised to develop consensus on (1) the landmarks to define the gastro-oesophageal junction (GOJ), (2) the occurrence and pathophysiological significance of the cardiac gland, (3) the definition of the gastro-oesophageal junctional zone (GOJZ) and (4) the causes of inflammation, metaplasia and neoplasia occurring in the GOJZ.

DESIGN

Clinical questions relevant to the afore-mentioned major issues were drafted for which expert panels formulated relevant statements and textural explanations.A Delphi method using an anonymous system was employed to develop the consensus, the level of which was predefined as ≥80% of agreement. Two rounds of voting and amendments were completed before the meeting at which clinical questions and consensus were finalised.

RESULTS

Twenty eight clinical questions and statements were finalised after extensive amendments. Critical consensus was achieved: (1) definition for the GOJ, (2) definition of the GOJZ spanning 1 cm proximal and distal to the GOJ as defined by the end of palisade vessels was accepted based on the anatomical distribution of cardiac type gland, (3) chemical and bacterial (Helicobacter pylori) factors as the primary causes of inflammation, metaplasia and neoplasia occurring in the GOJZ, (4) a new definition of Barrett's oesophagus (BO).

CONCLUSIONS

This international consensus on the new definitions of BO, GOJ and the GOJZ will be instrumental in future studies aiming to resolve many issues on this important anatomic area and hopefully will lead to better classification and management of the diseases surrounding the GOJ.

Differences in the molecular biology of adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

Adenocarcinoma of the distal esophagus, gastric cardia, and upper gastric third are grouped in type I-III by the Siewert classification. This classification is based on the endoscopic localisation of the tumor center, and is the most important diagnostic tool to group these tumors. On a molecular level, there is currently no marker that would allow to differentiate the three different types. Furthermore, the Siewert classification was not uniformly used in the recent literature, making interpretation and generalization of these results difficult. However, several potential targets have been identified that may help to separate these tumors by molecular markers, and are summarized in this chapter.

Targeting the Wnt signaling pathway to treat Barrett’s esophagus

Barrett's esophagus (BE) is an acquired condition in which the normal squamous epithelium in the distal esophagus is replaced by a metaplastic columnar epithelium, as a complication of chronic gastroesophageal reflux. The clinical significance of this disease is its associated predisposition to esophageal adenocarcinoma (EAC). Recently, and similarly to other human malignancies, the Wnt signaling pathway and its key component beta-catenin have been implicated in the carcinogenesis of BE. Although mutations in adenomatous polyposis coli (APC) or beta-catenin are rare in EAC, alterations of upstream components, such as overexpression of Wnt2 ligand or downregulation of Wnt antagonists may play dominant roles in the activation of the Wnt pathway. Increasing evidence suggests that inhibiting the Wnt pathway may be a new targeted therapy for the treatment of cancers and could, therefore, be promising for the cure of EAC, which remains a highly lethal disease.

Adenocarcinoma of the Esophagogastric Junction in China according to Siewert's classification

BACKGROUND

There had never been a clear definition of the cancer of cardia before Siewert's classification, which was proposed in 1996 and approved in 1997 at the second International Gastric Cancer Congress in Munich. On the basis of the classification, this study aims to research into the clinicopathological characteristics and surgical modes of adenocarcinoma of the esophagogastric junction in China.

METHODS

The study reviewed the data of the distal esophageal cancer, the cancer of cardia and the proximal gastric cancer at the First Hospital of Xi'an Jiaotong University from January 1995 to December 1999. Surgical patients were defined and classified according to Siewert's classification, and 203 patients were up to the classification. Then the study compared and analyzed the clinicopathological characteristics and the survival rates of the three types of the tumor.

RESULTS

Among the 203 patients, there were 29 patients with adenocarcinoma of the distal esophagus (Type I); 80 patients with true carcinoma of cardia (Type II); and 94 patients with subcardial carcinoma (Type III). Obvious differences were found in the clinicopathological characteristics of the three types, but no significant difference of the 5-year survival rates was found among the three types of patients with curative resection.

CONCLUSION

On the data, the distribution of the three types of tumor was found to be different from that reported in Western countries and in Japan; and the three types of patients who had undergone curative resection were found to have similar 5-year survival rates.

Clinicopathological significance of loss of heterozygosity in intestinal- and solid-type gastric carcinomas: a comprehensive study using the crypt isolation technique

The clinicopathological significance of loss of heterozygosity (LOH) in gastric carcinoma remains poorly understood. We and other researchers have previously demonstrated that LOH is fairly common in intestinal- and solid-type gastric carcinomas, but rare in diffuse-type tumors. In this study, we investigated the relationship between clinicopathological variables and LOH status in intestinal- and solid-type gastric carcinomas. The crypt isolation technique was utilized to analyze LOH at 1p36, 3p14, 4p15, 5q21-22, 8p11-12, 9p21, 13q22, 17p13.1 18q21 and 22q13.31 in 113 intestinal- and solid-type gastric carcinomas using a polymerase chain reaction assay. Immunostaining with D2-40 and Elastica van Gieson staining were used to detect lymphatic invasion and vessel invasion, respectively. High LOH rates (49-71%) were observed in all chromosomal regions tested. 1p36 loss was significantly associated with advanced tumors and lymph node metastasis. 8p11-12 loss was significantly associated with lymph node metastasis, lymphatic invasion, and vessel invasion. 17p13.1 (TP53) loss was significantly associated with vessel invasion. 22q13.31 loss was significantly associated with advanced tumors, lymph node metastasis, lymphatic invasion, vessel invasion and late TNM stage. No significant associations were observed between LOH at other chromosomal regions and aggressive behaviors. In addition, significantly higher LOH rates at 1p36, 9p21, 18q21 and 22q13.31 were observed in cardiac tumors compared with noncardiac tumors. These results suggest that in intestinal- and solid-type gastric carcinomas, LOH on 3p14, 4p15, 5q21-22, 9p21, 13q22 and 18q21 is associated with carcinogenesis, while LOH on 1p36, 8p11-12, 17p31.1 and 22q13.31 is associated with tumor progression.

Early-onset gastric cancers have a different molecular expression profile than conventional gastric cancers

Many studies examine the molecular genetics of gastric cancer, but few look at young patients in particular and there is no comparison of molecular expression between early-onset gastric cancer (< or = 45 years old) and conventional gastric cancers. Expression of cycloxygenase-2 (COX-2) is elevated in gastric adenocarcinomas compared to non-neoplastic mucosa, and in light of studies showing reduced risk of gastric cancer in nonsteroidal anti-inflammatory drug users, we have chosen to investigate the expression of COX-2 and related molecules in 113 early-onset gastric cancers and compare it with 91 conventional gastric cancers, using tissue microarrays. These markers include molecules known to be important in conventional gastric carcinogenesis, such as E-Cadherin, p53, COX-2, Trefoil Factor-1 (TFF1), beta-catenin, p16 and c-myc; as well as molecules not yet described as being important in gastric cancer, such as the transcription factor c-jun, the COX-2 mRNA stabilizer HuR, and C/EBP-beta, a transcription factor for COX-2. All markers showed a statistically significant difference between early-onset gastric cancers and conventional gastric cancers, using a chi2 test. In particular, early-onset gastric cancers displayed a COX-2 Low, TFF1-expressing phenotype, whereas COX-2 overexpression and loss of TFF1 was found in conventional cancers, and this difference between early-onset gastric cancers and conventional cancers remained statistically significant when adjusted for location and histology (P<0.0001 and P = 0.002 respectively). We found that COX-2 overexpression correlates significantly with loss of TFF1 (P = 0.001), overexpression of C/EBP-beta (P<0.001) and cytoplasmic HuR (P = 0.016). COX-2 was significantly associated with p53 positivity (P = 0.003). Abnormalities in E-Cadherin correlated significantly with diffuse phenotype, whereas high expression of COX-2, loss of TFF1 and overexpression of C/EBP-beta correlated with the intestinal phenotype. Our results provide further evidence that early-onset gastric cancer exhibits a distinctive expression profile that may have practical implications.

Differences and similarities of adenocarcinomas of the esophagus and esophagogastric junction

During the last few decades there has been an alarming rise in the incidence of tumors originating at the esophagogastric junction (EGJ) [1]. The reason for this is unknown. Tumors of the EGJ can be categorized in two types of cancer divided according to their anatomical origin: distal esophageal adenocarcinoma and adenocarcinoma of the gastric cardia. However, due to their location, in the transitional zone of the esophagus and stomach, there is constant debate about the proper classification, staging, and management of these tumors. The etiology of distal esophageal adenocarcinoma is clearly related to gastroesophageal reflux disease (GERD) and the development of a Barrett's esophagus [2]. The etiology of adenocarcinoma of the gastric cardia is less well understood. In the present paper, we will discuss the clinical characteristics and clinical management of esophagogastric tumors. Special attention will be given to differences and similarities of adenocarcinomas of the gastric cardia and distal esophagus.