Abstract
Squamous cell carcinomas generally show close morphological similarities to each other, but different features vary in prominence according to the degree of differentiation. Ultrastructure of different oral SCC types has been reported by a number of authors. The results of ultrastructural studies of oral squamous cell carcinoma (SCC) have provided a clearer understanding of the differences between well-differentiated and poorly-differentiated SCCs.
Disturbances in growth, including the carcinogenesis, are often linked with an increased rate of cell proliferation. Over the past few decades, there has been considerable interest in markers of cell proliferation that can be used as indicators of the histopathological grade and the tumor behavior of human cancers. The number of mitoses per high-power field is one of the morphological features used to grade oral SCC. Many studies utilizing immunohistochemical markers of cell cycle antigens, including PCNA and Ki-67, to derive a labeling index in oral carcinomas have been reported. These immunohistochemical methods are now widely accepted. The significance of prolif erative activity depends on the number of cells undergoing apoptosis. Disordered balance between proliferation and apoptosis may contribute to carcinogenesis. Bcl-2 has been shown to antagonize the cell death pathway. Overexpression of bcl-2 has been reported in a number of oral SCCs. p53 is also a key gene involved in human malignancies. p53 is known to be a tumor suppressor gene and can induce apoptosis of unnecessary cells. The avoidance of apoptosis by the mutation of the p53 can contribute to the development of a malignant tumor. Many studies have examined the relationship of overexpression of p53 protein with the statee of cell proliferation in oral carcinomas.
This review focuses on the relationship between the histopathological grade and the characteristics of SCC, which include the ultrastructural features, cell proliferation, and apoptosis-related genes.
