Reciprocal Cdc25A and p27 expression in B-cell non-Hodgkin lymphomas.

Cell cycle regulation is often altered in cancer and deregulation of the cell cycle checkpoints is common in human neoplasia. The dual-specificity phosphatase Cdc25A and the cell cycle inhibitor p27 both play an important role in the regulation of the G1-S transition. We evaluated Cdc25A mRNA expression by in situ hybridization and p27 protein expression by immunohistochemistry in 42 histologically indolent B-cell non-Hodgkin lymphoma (NHL and 51 histologically aggressive B-cell NHL. Overexpression of Cdc25A (>50% tumor cells positive) was detected in 5 of 42 cases (12%) of histologically indolent B-cell NHL and in 29 of 51 (57%) of histologically aggressive B-cell NHL (P < 0.001). In contrast, high p27 protein expression (>50% tumor cells positive) was observed in 29 (69%) cases of indolent but in only one case (2%) of aggressive B-cell NHL (P < 0.0001). Thus, overexpression of Cdc25A and concomitant loss of p27 expression are associated with high grade B-cell NHL and may contribute to their aggressive biologic behavior.