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Cyclin E, a Potential Prognostic Marker in Breast Cancer.

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Aunnal rept. 1 Oct 96-39 Sep 97,

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We have examined tumor specimens from 400 breast cancer patients, comparing the changes of cyclin E expression with seven other established tumor markers as well as patient outcome. Altered expression of cyclin E was observed in 90 of all breast cancers with poor prognosis where patients either died of breast cancer or were still with cancer at the last contact date. Similarly in 85 of all breast cancer patients where cyclin E was either not altered, or its alteration was minimal, patients had a favorable prognosis. We also examined the expression of cyclin D and PCNA in the same group of patients and found while cyclin D was overexpressed in 4O of all cases examined, such overexpression was not linked to poor prognosis or to cyclin E overexpression. Lastly, overexpression of PCNA, indicative of highly proliferative cancer, was not sufficient to account for such high association of cyclin E expression to poor prognosis. These analysis revealed that cyclin E protein is the most consistent marker for determining the prognosis of early-stage node-negative ductal carcinoma, providing very strong evidence for the use of cyclin E as a novel prognostic marker for breast cancer. The alteration of cyclin E in breast cancer has been further characterized and reveals that while cyclin E is cell cycle regulated in normal cells, it is present constitutively and in an active complex in synchronized populations of breast cancer cells. Since cyclin E is active throughout the cell cycle in tumor and not normal cells, it functions redundantly and activates substrates in only tumor cells.

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  • Medicine and Medical Research

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