Potential prognostic value of mitogen-activated protein kinase activity for disease-free survival of primary breast cancer patients

Signaling through pathways involving mitogen-activated protein kinases (MAP kinases) has been implicated in the pathogenesis of cancer. Thus, the acti vity of MAP kinase is essential in the malignant potential of human breast tumors. p42/44(MAPK) was significantly higher expressed in tumor samples th an in matching normal tissues adjacent to the tumor. p42/44(MAPK) protein e xpression correlated with enhanced MAP kinase activity only in a subset of tumors, indicating that over-expression of MAP kinases does not reflect the activation status of these enzymes. MAP kinase activity was significantly elevated in 131 tissue samples from primary breast tumors when compared to 18 normal tissues adjacent to tumors. A trend for higher MAP kinase activit y in primary tumors of node-positive patients was observed when compared wi th tumors from node-negative patients. Similarly, higher MAP kinase activit ies were observed in specimens from patients who had a relapse within the f ollow-up time of 40 months when compared with patients with no relapse. A s urvival analysis demonstrated that the MAP kinase activity in primary breas t tumors is potentially prognostic for relapse-free survival of patients. ( C) 2000 Wiley-Liss, Inc.