SIGNIFICANCE OF THE EXPRESSION OF PROLIFERATION-ASSOCIATED NUCLEOLAR ANTIGEN P120 IN HUMAN COLORECTAL TUMORS

Nucleolar protein p120 is considered to be associated with cell prolif eration and has also been detected in a broad range of human malignant cells and tissues, but not in either normal resting tissue or most be nign tumors. To clarify the significance of the expression of p120 in colorectal tumors or to evaluate the contribution of p120 in the devel opment of colorectal carcinoma, the authors developed a monoclonal ant ibody against p120 and then examined its expression in adenoma, carcin oma, and normal mucosa. In adenomas, p120 expression was shown in none of 13 cases of mild dysplasia (0%), 2 of 15 of moderate dysplasia (13 .3%), and in 2 cases of severe dysplasia (100%). p120-positive adenoma s of moderate dysplasia tended to be larger and had higher Ki-67 index es than the negative ones (adenomas of moderate dysplasia). All 27 car cinomas were positive for p120. p120 immunostaining was found in the n uclei and corresponded closely to the prominent nucleoli of tumor cell s. In contrast, either weak or the occasional expression of p120 nas t raced in only one of the nine normal mucosae (11.1%). Three of the tra nsitional mucosae of the carcinoma were also positive for p120. The pe rcentage of p120-positive tumor cells (p120 index) ranged from 3.2% to 86.6%, and the mean p120 indexes of the four adenomas and all carcino mas were 21.3% and 41.5%, respectively. The p120 index was significant ly related to the Ki-67 index (P < .001) in the p120-positive tumors, whereas the p120 index of the carcinoma did not significantly correlat e to the known prognostic markers, such as tumor size, stage, or the d egree of differentiation. These results thus suggest that the expressi on of p120 serves as a marker for cells with a high proliferative pote ntial and is linked to the late events of colorectal tumor progression . Copyright (C) 1997 by W.B. Saunders Company.