Serum gastrin levels in patients with intestinal and diffuse type of gastric cancer

Gastrin-17 Combined with CEA, CA12-5 and CA19-9 Improves the Sensitivity for the Diagnosis of Gastric Cancer

Background

Previous studies reported the utility of serum tumor markers (such as CEA, CA12-5 and CA19-9) and gastrin-17 in the diagnosis of gastric cancer (GC). However, the value of these serum markers for diagnosing GC is still under debate. In this study, we aimed to evaluate the effect of gastrin-17, CEA, CA12-5 and CA19-9 in the diagnosis of GC.

Methods

The level of CEA, CA12-5, CA19-9 and gastrin-17 was tested in 230 GC patients and 99 healthy people. The value of the four markers for diagnosing GC was analyzed.

Results

The positive rate of Gastrin-17, CEA, CA19-9 and CA12-5 was much higher in GC group (22.61%, 22.61%, 20.00% and 8.26%, respectively) than that of healthy control group (5.05%, 2.02%, 1.01% and 2.02%, respectively). The sensitivity of Gastrin-17, CEA, CA12-5 and CA19-9 in the diagnosis of GC was 22.61%, 22.61%, 6.96% and 20.00%, respectively, and the corresponding specificity was 94.95%, 97.98%, 98.99% and 98.99%, respectively. By using the optimal cut-off value derived from the area under curve (AUC) of receiver operating characteristic curve, the AUC of gastrin-17, CEA, CA12-5, CA19-9 increased to 0.72, 0.64, 0.61 and 0.65, respectively. After combining the four markers, the AUC increased to 0.79 (95% CI: 0.75-0.84), and the corresponding sensitivity and specificity were 65.22% (95% CI: 58.70-71.40%) and 84.85% (95% CI: 76.20-91.30%), respectively, which were significantly higher than those of separate markers (P < 0.05).

Conclusion

CEA, CA12-5, CA19-9 and gastrin-17 were all valuable in the diagnosis of GC, and gastrin-17 had the best diagnostic value among the four markers. Gastrin-17 combined with CEA, CA12-5 and CA19-9 could improve the diagnostic value of GC significantly. Prospective, multi-center studies are needed to validate our findings.

Not only stem cells, but also mature cells, particularly neuroendocrine cells, may develop into tumours: time for a paradigm shift

Stem cells are considered the origin of neoplasms in general, and malignant tumours in particular, and the stage at which the stem cells stop their differentiation determines the degree of malignancy. However, there is increasing evidence supporting an alternative paradigm. Tumours may develop by dedifferentiation from mature cells able to proliferate. Studies of gastric carcinogenesis demonstrate that mature neuroendocrine (NE) cells upon long-term overstimulation may develop through stages of hyperplasia, dysplasia, and rather benign tumours, into highly malignant carcinomas. Dedifferentiation of cells may change the histological appearance and impede the identification of the cellular origin, as seen with gastric carcinomas, which in many cases are dedifferentiated neuroendocrine tumours. Finding the cell of origin is important to identify risk factors for cancer, prevent tumour development, and tailor treatment. In the present review, we focus not only on gastric tumours, but also evaluate the role of neuroendocrine cells in tumourigenesis in two other foregut-derived organs, the lungs and the pancreas, as well as in the midgut-derived small intestine.

Expression of the Cholecystokinin-B Receptor in Neoplastic Gastric Cells

Gastric cancer is an important disease due to its high mortality. Despite the decline in frequency, most cases are discovered late in its course, and most of the cancer patients die within a few years of diagnosis. In addition to Helicobacter pylori gastritis, gastrin is considered an important factor in the development of this disease, and thus, cholecystokinin-B receptor (CCKBR) becomes of interest. The aim of our study was to explore whether CCKBR is expressed in stomach cancers. Thirty-seven tumors from 19 men and 18 women diagnosed with either adenocarcinoma or neuroendocrine neoplasm (NENs) were included in this study. The tumors were classified into 29 adenocarcinomas and eight NENs. Immunohistochemistry with antibodies against chromogranin A (CgA), synaptophysin and CCKBR, and in situ hybridization with probes against CgA, CCKBR and histidine decarboxylase were used to further explore these tumors. Thirty-three (89%) of the tumors expressed CCKBR protein, whereas only 20 (54%) of all tumors expressed CCKBR mRNA. Of the 20 tumors expressing CCKBR mRNA, eight were NENs and 12 were adenocarcinoma. The highest amount of CCKBR was expressed in NEN. Interestingly, a high degree of co-expression of CCKBR and CgA was observed when the two markers were examined together with in situ hybridization. In conclusion, we found that all eight NENs expressed CCKBR and neuroendocrine markers in a majority of tumor cells. The same markers were also expressed in a proportion of adenocarcinomas supporting the view that gastrin is important in the development of gastric cancer.

Gastrin and Gastric Cancer

Gastric cancer although occurring in reduced frequency is still an important disease, partly because of the bad prognosis when occurring in western countries. This decline in occurrence may mainly be due to the reduced prevalence of Helicobacter pylori (Hp) infection, which is the most important cause of gastric cancer. There exist many different pathological classifications of gastric carcinomas, but the most useful seems to be the one by Lauren into intestinal and diffuse types since these types seldom transform into the other and also have different epidemiology. During the nearly 30 years that have passed since the groundbreaking description of Hp as the cause of gastritis and gastric cancer, a continuous search for the mechanism by which Hp infection causes gastric cancer has been done. Interestingly, it is mainly atrophic gastritis of the oxyntic mucosa that predisposes to gastric cancer possibly by inducing hypoacidity and hypergastrinemia. There are many arguments in favor of an important role of gastrin and its target cell, the enterochromaffin-like cell, in gastric carcinogenesis. The role of gastrin in gastric carcinogenesis implies caution in the long-term treatment with inhibitors of gastric acid secretion inducing secondary hypergastrinemia, in a common disease like gastroesophageal reflux disease.

Importance of gastrin in the pathogenesis and treatment of gastric tumors

In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue remodelling and angiogenesis. Elevated serum concentrations of this hormone are caused by many conditions, particularly hypochlorhydria (as a result of autoimmune or Helicobacter pylori (H pylori)-induced chronic atrophic gastritis or acid suppressing drugs) and gastrin producing tumors (gastrinomas). There is now accumulating evidence that altered local and plasma concentrations of gastrin may play a role during the development of various gastric tumors. In the absence of H pylori infection, marked hypergastrinemia frequently results in the development of gastric enterochromaffin cell-like neuroendocrine tumors and surgery to remove the cause of hypergastrinemia may lead to tumor resolution in this condition. In animal models such as transgenic INS-GAS mice, hypergastrinemia has also been shown to act as a cofactor with Helicobacter infection during gastric adenocarcinoma development. However, it is currently unclear as to what extent gastrin also modulates human gastric adenocarcinoma development. Therapeutic approaches targeting hypergastrinemia, such as immunization with G17DT, have been evaluated for the treatment of gastric adenocarcinoma, with some promising results. Although the mild hypergastrinemia associated with proton pump inhibitor drug use has been shown to cause ECL-cell hyperplasia and to increase H pylori-induced gastric atrophy, there is currently no convincing evidence that this class of agents contributes towards the development of gastric neuroendocrine tumors or gastric adenocarcinomas in human subjects.

Concomitant gastrin and ERBB2 gene amplifications at 17q12-q21 in the intestinal type of gastric cancer

Our recent studies using comparative genomic hybridization showed that gain or amplification at the 17q12-q21 region is very common in the intestinal type of gastric cancer. Here, we describe a fluorescence in situ hybridization study with gastrin (GAS)-specific and ERBB2-specific probes on ten specimens of gastric carcinoma that, by using comparative genomic hybridization, showed 1) DNA copy number gain or amplification at 17q12-q21, a region known to harbor the GAS and ERBB2 genes (four cases); 2) gain of the entire chromosome 17 (three cases); or 3) normal copy number of chromosome 17 (three cases). GAS and ERBB2 protein expression was studied by Western immunoblotting from gastric cancer cell lines with or without gain at 17q12-q21 as well as a breast cancer cell line with ERBB2 amplification. Our results showed that simultaneous amplification of both GAS and ERBB2 was four- to ninefold in the tumors with the 17q12-q21 amplification. Both genes were amplified in the same nuclei, and the hybridization signals were localized to the same region of the nucleus. Overexpression of GAS and ERBB2 was observed by Western immunoblotting only in the gastric cancer cell line with gain at 17q12-q21. The ERBB2 amplification is also a recurrent change in breast cancer. To investigate whether the GAS amplification is unique in gastric cancer, fluorescence in situ hybridization analysis was performed on 40 breast cancer cell lines. The ERBB2 amplification was observed in 11 cell lines, but none of the lines showed the GAS amplification. This indicates that the formation of an amplicon, in which both the GAS and the ERBB2 genes are amplified, might be unique in gastric cancer, especially in its intestinal type, and that simultaneous amplification of both genes is important to the tumorigenesis of intestinal gastric cancer. We demonstrate here for the first time that a gene of a physiological hormone is amplified in tumors that originate from cells that normally secrete the hormone.

Comparative genomic hybridization reveals differences in DNA copy number changes between sporadic gastric carcinomas and gastric carcinomas from patients with hereditary nonpolyposis colorectal cancer

Comparative genomic hybridization was used to search for DNA copy number changes in samples of gastric cancer from 12 hereditary nonpolyposis colon cancer (HNPCC) patients and in samples of sporadic gastric carcinoma from 13 patients. The gastric cancer samples from HNPCC patients showed gains affecting 19q, Xp, and whole chromosome 22, each in a single patient. Neither high-level amplifications nor losses of DNA copy number were detected. On the other hand, 10 of the 13 (77%) sporadic gastric carcinoma samples had multiple DNA copy number changes. The most frequent gains occurred with minimal common overlapping regions at 1q22-q31, 8q23-qter, 17p11.2-q22, and 20q, all at a frequency of 31%. High-level amplifications were also seen at 17q21 in three cases (23%). Losses were rare, and the most frequent loss was with a minimal common overlapping region at 4q32 (23%). This suggests that multiple DNA copy number changes are needed for the development of sporadic gastric carcinoma but not for gastric carcinoma in HNPCC patients.

Relationship of ECL cells and gastric neoplasia

The enterochromaffin-like (ECL) cell in the oxyntic mucosa has a key role in the regulation of gastric secretion since it synthesizes and releases the histamine regulating the acid secretion from the parietal cell. Gastrin is the main regulator of the ECL cell function and growth. Long-term hypergastrinemia induces ECL cell hyperplasia, and if continued, neoplasia. ECL cell carcinoids occur in man after long-term hypergastrinemia in conditions like pernicious anemia and gastrinoma. There is also accumulating evidence that a proportion of gastric carcinomas of the diffuse type is derived from the ECL cell. Furthermore, the ECL cell may, by producing substances with angiogenic effects (histamine and basic fibroblast growth factor), be particularly prone to develop malignant tumors. Although the general opinion is that gastrin itself has a direct effect on the oxyntic mucosal stem cell, it cannot be excluded that the general trophic effect of gastrin on the oxyntic mucosa is mediated by histamine or other substances from the ECL cell, and that the ECL cell, therefore, could play a role also in the tumorigenesis/carcinogenesis of gastric carcinomas of intestinal type.

17q12-21 amplicon, a novel recurrent genetic change in intestinal type of gastric carcinoma: a comparative genomic hybridization study

We studied DNA copy number changes in gastric cancer (GC) using comparative genomic hybridization (CGH) analysis on 35 resected gastric carcinomas (22 of the intestinal type and 13 of the diffuse type). Eighty-three percent of the cases showed DNA copy number changes. Gains were more common than losses (median of 3 and 1 in primary tumors of the intestinal and diffuse type, respectively). The most common gains were detected on 20q [46%; 12 intestinal type (55%) and four diffuse type (31%)], 8q [37%; 10 intestinal type (45%) and three diffuse type (23%)], and 17q12-21 [29%; all but one intestinal type (41%)]. The most frequent losses were detected on 18q [26%; all intestinal type (41%)] and on 4q [23%; all intestinal type (32%)]. High-level amplifications were observed in the intestinal type of tumors at 17q12-21 (three tumors), 20q (three tumors). 2q (one tumor), and 18q (one tumor). In the diffuse type, high-level amplification was detected once at 13q.