Expression of proliferating cell nuclear antigen in polyps from large intestine

Colon cancer has a high incidence in the world, especially in Western countries, and the incidence is also increasing in China in recent years. To reduce the incidence, it is essential to identify individuals at high risk and to eradicate risk factors. Although colorectal neoplasia is a multi-stage process, hyperproliferation is the main factor leading to the initiation of carcinogenesis. In animal models of colonic cancer, an increased colonic proliferative rate resulted from inherited differences, pharmacological or surgical intervention, which increase the susceptibility of the colonic mucosa to carcinogens. On the other hand, interventions that decrease colonic proliferation are associated with decreased susceptibility to carcinogens. PCNA (proliferating cell nuclear antigen) is an accessory protein of DNA polymerase and is thought to play an important role in the elongation or replication of the DNA chain. Its accumulation in the nucleus during the G-1 and S stages of the cell cycle has been reported, and the labeling index, which is the percentage of PCNApositive cells, has been reported to be correlated with the proliferative activity and the prognosis of various ma lignant tumors. Thus it is valuable to assess what ro le PCNA plays dur ing the transformation of the colonic polyps to colonic cancer.