Expression of survivin, p53, and caspase 3 in Barrett's esophagus carcinogenesis

The regulation of apoptosis, as a distinctive form of programmed cell death, in multistep Barrett's esophagus (BE) carcinogenesis is poorly understood. The aim of this study was to investigate, in the intestinal metaplasia-dysplasia-carcinoma sequence, the role of survivin, an inhibitor of apoptosis; the p53 protein, a tumor suppressor gene involved in cell cycle control; and caspase 3, a protease-inducing apoptosis and inhibited by survivin. Immunohistochemical expression was tested in 40 cases of BE, including 11 low-grade and 19 high-grade dysplasias (HGD), and samples were obtained from 40 surgical specimens of esophagectomy performed for HGD or Barrett's adenocarcinoma. To define the deregulation time of the proteins, overexpression was evaluated in relation to the proliferative and/or maturative compartment. In BE, cytoplasmic expression of survivin and caspase 3 (100% of cases) was significantly higher than expression of p53 (25%). The latter increased with increasing grade of dysplasia. In BE, the expression of survivin, p53, and caspase 3 mainly involved the proliferative compartment, whereas in LGD and HGD, the 3 proteins were coexpressed in both proliferative and maturative compartments. These results indicate that survivin overexpression is an early event in the proliferative compartment of BE, preceding both p53 accumulation and dysplastic changes. Cytoplasmic survivin location may indicate an initial antiapoptotic, more than proliferative, role in the early phases of Barrett carcinogenesis. Expression of caspase 3 in BE and dysplasia may be ascribed to accumulation of the nonactivated form, as the antibody used detects both cleaved and uncleaved caspase 3.