An immunohistochemical study of p16, pRb, p21 and p53 proteins in human esophageal cancers.

Background. Cell cycle-associated proteins, p16, pRb p21 and p53 are important in regulating the G1-S checkpoint in the cell cycle, and their functional alterations play key roles in carcinogenesis and cell proliferation. Materials and Methods. We immunohistochemically examined the expression of p16, pRb, p21 and p53 proteins by using surgically resected tissues from 35 patients with primary esophageal cancers. Results. In 35 esophageal cancers, the expressions of p16, pRb, p21 and p53 proteins were detectable in 4(11.4%), 25(71.4%), 11(31.4%) and 20(57.1%) respectively. Interestingly, 24 of 25 pRb positive cancers (96.0%) had negative p16, whereas three of ten pRb-negative cancers (30.0%) had high levels of p16 (p<0.05). In 11 cases of p21 positive immunostaining, there was lymph node metastasis (pNI) in 9 (81.8%). Conclusions. These results suggest that abnormalities of p16 protein may be closely associated with the carcinogenesis or cell proliferation of esophageal cancers.