CYCLIN-E, A POTENTIAL PROGNOSTIC MARKER FOR BREAST-CANCER

A fundamental cause of cancer is changed properties of genetic materia l, which may deregulate normal development of the tissue or provide se lective growth advantage to the tumor cell. This deregulation of cell proliferation results from altered production of a handful of proteins that play key roles in progression through the eukaryotic cell cycle. Some of these proteins include tumor suppressor genes or oncogenes. H owever, no one general change or alteration of a critical gene has yet been found in all cancers. Using surgical material obtained from pati ents with various malignancies, we show that breast cancers and other solid tumors, as well as malignant lymphocytes from patients with lymp hatic leukemia, show severe quantitative and qualitative alterations i n cyclin E protein production independent of the S-phase fraction of t he samples. Hence, these alterations represent a true difference betwe en normal versus tumor tissue. In addition, in breast cancer, the alte rations in cyclin E expression become progressively worse with increas ing stage and grade of the tumor, suggesting its potential use as a ne w prognostic marker.