p53 overexpression in human esophageal carcinoma: A correlation with tumor DNA ploidy and two parameter flow cytometric study

Abnormalities of p53, a known tumor suppressor gene, has been detected in various human malignant neoplasms. In this study, we analyzed immunohistochemically the localization of p53 using three different antibodies, PAb1801, DO-7, and CM-1 in 49 patients with esophageal squamous cell carcinoma. We compared the expression of p53 with the clinicopathological features, proliferating cell nuclear antigen (PCNA), and DNA ploidy. In addition, we performed flow cytometric analysis of p53 using DO-7 in 33 cases in order to evaluate the correlation between p53 overexpression and DNA ploidy simultaneously. By immunohistochemistry, immunoreactive p53 was observed in the nuclei of carcinoma cells in 29 cases (59%). Relatively larger diameter tumors (more than 5 cm), poorly differentiated tumors, tumors with distant lymph node metastasis, and DNA aneuploidy tumors were positive for p53 more frequently. p53-positive cases had a higher PCNA labeling index and a poorer prognosis than p53-negative cases. By two parameter flow cytometric analysis, p53 was detected in 16 cases (49%) and DNA aneuploidy was detected in 27 cases (82%). A higher p53-positive rate (15/27,56%) was observed in DNA aneuploidy cases than in DNA diploidy cases (1/6,17%). However, this difference was not statistically significant. The p53 results by immunohistochemistry and flow cytometry were the same in 25 out of 33 cases (76%). These results suggest the possible correlation between p53 abnormalities and DNA aneuploidy and that analysis of p53 protein is useful for prediction of clinical course in esophageal squamous cell carcinoma.