THE C-ERBB TRANSMEMBRANE GROWTH-FACTOR RECEPTORS AS SERUM BIOMARKERS IN HUMAN CANCER STUDIES

Over-expression of the transmembrane growth factor receptors encoded b y the c-erbB oncogenes contributes to cellular transformation in model systems and is found to be a frequent occurrence in human tumors. Ove r-expression of these receptors results in accumulation of the extra-c ellular domain in the extra-cellular supernatant in vitro and in eleva ted levels of the extra-cellular domain in serum in vivo in animal mod els. Similarly, elevated levels of the extra-cellular domain of these receptors have been detected in the serum of individuals with various cancers, including of the breast, ovary, prostate, stomach, pancreas, colon, liver, and lung. In some cases, elevated serum levels have been detectable prior to the time of clinical diagnosis of disease. Thus, the serum levels of the extra-cellular domains of the c-erbB transmemb rane growth factor receptors may be useful biomarkers of carcinogenesi s in human studies.