Aims: Cell cycle regulatory proteins were analysed by immunohistochemistry in order to clarify how their expression changes with the degree of atypia as oesophageal surface squamous epithelium progresses from normal mucosa, through reactive change, low-grade dysplasia, and high-grade dysplasia to mucosal invasive carcinoma.
Methods and results: Immunostaining for cyclin D1, cyclin E, p21, p27, p53 and Ki67 proteins was performed using 22 normal mucosa, 17 reactive change, 22 low-grade dysplasia, 15 high-grade dysplasia and 22 mucosal invasive carcinoma specimens. Normal mucosa, low-grade dysplasia and high-grade dysplasia samples were taken from patients without any oesophageal invasive carcinoma by endoscopic biopsy or endoscopic mucosal resection, and reactive change and mucosal invasive carcinoma were obtained from oesophagectomy material. Stepwise over-expression of cyclin E (P < 0.0001) and p53 (P < 0.0001), reduction of p21 (P=0.0189) and dysregulation of cyclin D1 and p27 were observed in the multistep process of oesophageal carcinogenesis. Significant differences in expression of p27 (P < 0.0001), p53 (P=0.0299) and Ki67 (P=0.0101) were observed between reactive change and low-grade dysplasia. Furthermore, expression of cyclin D1, cyclin E, p27 and p53 in mucosal invasive carcinoma were significantly different from those in high-grade dysplasia (P=0.0079, P=0.0237, P=0.0042 and P= 0.0299, respectively).
Conclusions: Cell cycle regulatory proteins, cyclin E, p53 and p21 show stepwise over-expression or reduction with progression of oesophageal carcinogenesis, correlating with the increased cell proliferation observed with Ki67 labelling. We conclude that immunohistochemical analysis for p27, p53 and Ki67 is practically useful for the discrimination between low-grade dysplasia and reactive change. Cyclin D1, cyclin E, p27 and p53 help to distinguish high-grade dysplasia from mucosal invasive carcinoma.