Expression of cell cycle inhibitor p27 and Ki-67 in human adrenocortical neoplasms

Recent immunohistochemical analysis of cell cycle-related proteins such as p27, a cell cycle inhibitory protein, and Ki-67, a proliferation marker, in dicated their possible values in predicting the biologic behavior of variou s human neoplasms. In this study, we performed an immunohistochemical analy sis of p27 and Ki-67 in 42 adrenocortical neoplasms (12 adrenocortical carc inomas, 24 adrenocortical adenomas) and 6 normal adrenal glands to evaluate their possible values in diagnosing adrenocortical malignancy and in predi cting the biologic behavior of carcinomas. We detected Ki-67 and p27 immuno reactivity in the nuclei of all of our cases, and we observed a significant negative correlation (r = -0.572, P <.001) between the p27 and Ki-67 label ing indexes (LIs). The LIs of p27 and Ki-67 were 61.7 +/- 2.6 and 0.28 +/- 0.08 in the normal adrenal cortex and 59.4 +/- 6.5 and 0.33 +/- 0.11 in the adenomas, respectively, with no significant differences between the LIs of the adenomas and normal adrenals. The LIs of p27 and Ki-67 in the carcinom as were 48.9 +/- 7.5 and 630 +/- 6.21, respectively. The LI of p27 in the c arcinomas was significantly lower than that in the adenomas, The LI of Ki-6 7 in the carcinomas was significantly higher than that in the adenomas (P < .01). Among carcinoma cases, the Ki-67 LI in living cases tended to be lowe r than that in deceased cases, and the p27 LI in living cases tended to be higher than that in deceased cases, but these differences did not reach sta tistical significance. These results indicated that decreased p27 protein e xpression might cause increased cell proliferation in adrenocortical carcin oma cells in combination with other positive and/or negative regulators of the cell cycle. These results also suggested that immunohistochemical analy sis of p27 and Ki-67 might be useful in distinguishing between adrenocortic al adenoma and carcinoma.