Overexpression of CDC25B phosphatase as a novel marker of poor prognosis of human colorectal carcinoma

There is evidence to suggest that CDC25B phosphatase is an oncogenic protei n. To elucidate the role of CDC25B in colorectal carcinoma, we examined the expression of CDC25B at the mRNA and protein levels. Reverse transcription -PCR assay indicated that CDC25B was overexpressed in tumor tissues relativ e to normal mucosa in 6 of 10 cases. Using immunohistochemistry, we identif ied high expression of CDC25B in 77 of 181 colorectal cases (43%). Univaria te analysis showed that high expression was a significant predictor for poo r prognosis compared with low expression (5-year survival rate; 59% versus 82%, respectively; P < 0.0001). Multivariate analysis indicated that CDC25B was an independent prognostic marker (risk ratio for death, 3.7; P < 0.000 1) even after controlling for various factors such as lymph node metastasis , tumor size, degree of differentiation, and depth of invasion. Furthermore , the level of CDC25B expression clearly predicted the outcome of patients with Dukes' B and Dukes' C tumors. On the other hand, CDC25A mRNA was overe xpressed in 9 of 10 colorectal cancer cases, and immunohistochemistry for C DC25A showed high expression in 52 of 111 cases (47%), but no significant c orrelation with prognosis. Our findings suggest that CDC25B is a novel inde pendent prognostic marker of colorectal carcinoma and that it may be clinic ally useful for selecting patients who could benefit from adjuvant therapy.