Clonality analysis of neuroendocrine cells in gastric adenocarcinoma

To achieve a better understanding of the origination of neuroendocrine (NE) cells in gastric adenocarcinoma.

In this study, 120 cases of gastric adenocarcinoma were obtained. First, frozen section-immunohistochemistrical samples were selected from a large quantity of neuroendocrine cells. Second, laser capture microdissection was used to get target cells from gastric adenocarcinoma and whole genome amplification was applied to get a large quantity of DNA for further study. Third, genome-wide microsatellite abnormalities [microsatellite instability (MSI), loss of heterozygosity (LOH)] and p53 mutation were detected by polymerase chain reaction (PCR)-single-strand conformation polymer- phism-silver staining and PCR-sequencing in order to identify the clonality of NE cells.

The total incidence rate of MSI was 27.4%, while LOH was 17.9%. Ten cases had a highest concordance for the two types of cells. The other samples had similar microsatellite changes, except for cases 7 and 10. Concordant p53 mutations exhibited in sample 4, 14, 21 and 27, and there were different mutations between two kinds of cells in case 7. In case 17, mutation took place only in adenocarcinoma cells. p53 mutation was closely related with degree of differentiation, tumor-node-metastasis stage, vessel invasion and lymph node metastasis. In brief, NE and adenocarcinoma cells showed the same MSI, LOH or p53 mutation in most cases (27/30). In the other three cases, different MSI, LOH or p53 mutation occurred.

NE and the gastric adenocarcinoma cells may mainly derive from the same stem cells, but the remaining cases showing different origin needs further investigation.