Detection of cyclin D1 overexpression by real-time reverse-transcriptase-mediated quantitative polymerase chain reaction for the diagnosis of mantle cell lymphoma

The diagnosis of mantle cell lymphoma (MCL) is particularly important for clinical management because of a remarkable prognostic difference between MCL and other types of B-cell lymphoma. In addition to immunohistochemical analysis, we have established a 5' exonuclease-based real-time reverse transcriptase-mediated quantitative polymerase chain reaction (RQ-PCR) method to detect cyclin DI overexpression for the diagnosis of MCL. The RQ-PCR could detect cyclin DI overexpression in all nine examined MCL cases, in contrast genomic PCR detected t(11;14) in only two of nine cases. By RQ-PCR the expression of G6PDH was significantly higher in myeloid leukemias than those in B-cell lymphomas (P = 0.018). As a result, cyclin D1/G6PDH ratio ranged from 0.78 to 12.4 (mean, 1.83) in MCL, exclusively higher than those in other B-cell lymphoma. (0.00009 similar to 0.16) and myeloid leukemia (0.00011 similar to 0.085). The high expression of cyclin DI in certain myeloid leukemias was identified to reflect their proliferative activity and not to represent the oncogenic overexpression. The 95% confidence interval of the cyclin D1/G6PDH ratio was 0.29 similar to 11.1 for MCL, 0.014 similar to 0.25 for other B-cell lymphomas and 0.000014 similar to 0.083 for myeloid leukemia, suggesting that a cutoff value can be set at 0.25. The RQ-PCR of cyclin D1 is convenient and especially useful for the diagnosis of MCL.