Expression of p53 and flow cytometric DNA analysis of isolated neoplastic glands of the stomach: an application of the gland isolation method

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.

DNA ploidy and its clinical implications in gastric cancer

BACKGROUND

Biological characteristics of gastric cancer depend mostly on genetic alterations in the cancer cells of individuals. To precisely predict the biological behavior and clinical outcome of individual cancer, it may be important to clarify the DNA profiles of cancer cells in each case.

METHODS

We have reviewed the most important results of studies on DNA ploidy of gastric cancer published in the English literature during the last 2 decades.

RESULTS

Gastric carcinoma with aneuploidy has been shown to have a high proliferative activity and a high metastatic or invasive potential, thus leading to a poor prognosis as compared to diploid tumors.

CONCLUSION

Analyses of DNA ploidy in gastric cancer may provide clinically useful information on diagnostic, therapeutic, and prognostic aspects. Further investigations may be needed to clarify the relationship between chromosome instability and DNA ploidy.

Infrequent overexpression of p53 protein in Epstein-Barr virus-associated gastric carcinomas

Epstein-Barr virus (EBV) infection was studied in a total of 412 patients with poorly differentiated gastric adenocarcinoma by in situ hybridization for EBV-encoded small RNA. EBV-specific RNA was detected in tumor cell nuclei of 83 (20.1%) of 412 gastric carcinomas, of which 60 were histologically subclassified as gastric carcinoma with lymphoid stroma (GCLS). All EBV-positive gastric carcinomas as well as 90 randomly selected EBV-negative gastric carcinomas were further studied for p53 protein expression by immunohistochemistry. The overexpression of p53 protein was demonstrated in only 7 (8.4%) of 83 EBV-positive gastric carcinomas. This was in marked contrast to the frequency of 34.4% in EBV-negative gastric carcinomas. In addition, a few p53-positive nuclei were characteristically scattered in the tumors of many EBV-positive GCLS, but this was not regarded as p53 overexpression arising from mutation of the gene. Our findings suggested that EBV-associated gastric carcinomas may arise through a different mechanism from other types of gastric carcinomas without EBV infection.