Histopathological analysis of apoptosis, and expression of p53, bcl-2, bax, and Ki-67 in laryngeal squamous cell carcinomas and dysplasia

The growth of neoplasia is determined by the proliferation and loss of cells. The purpose of this study is to determine the frequency of apoptosis in laryngeal carcinomas and to examine its relationship to the pathological parameters, including ki-67 expression, and to expression of p53, bcl-2, and bax protein. The materials are 67 cases of laryngeal squamous cell carcinomas (SCCs) and 22 cases of squamous dysplasia using biopsy and surgery specimens. Apoptotic cells were determined by the modified TUNEL method. Expressions of p53, bcl-2, and bax, i.e. apoptosis-related genes, and ki-67, a proliferation marker, were immunohistochemically examined. The relationships between apoptosis and the clinicopathological findings were studied. The stage of the carcinoma was not related to the apoptotic index. The expression of p53 was frequently detectable in the advanced carcinomas with T3, T4 and N-positive. The apoptotic index was not significantly related to recurrence, metastasis or histological differentiation. Apoptosis occurred frequently in the cornified areas of well differentiated SCCs. The expressions of ki-67 observed in the poorly differentiated SCCs was significantly higher than that observed in the well differentiated SCCs (P<0.01). The apoptotic index increased after irradiation in the carcinoma. No relationship was found between apoptotic index, ki-67 index, and expression of p53, bcl-2 and bax. The apoptotic index obtained form the SCCs was significantly higher than that obtained form squamous dysplasias (P<0.05). Various apoptosis-related findings including p53 expression were observed in the advanced type of laryngeal SCCs, and apoptosis of the carcinoma was suggested to be controlled by complicated factors including bcl-2.