Overexpression of the epidermal growth factor receptor family in gastric cancer suggests a role in tumor pathogenesis

Although the incidence of gastric cancer is decreasing, it is still the fifth leading cause of cancer death in Western countries. The reasons for the poor prognosis and the unresponsiveness to chemotherapy and radiotherapy are not known. Recently, growth factor receptors have been shown to play a role in the carcinogenesis and progression of various types of human cancer. In the present study, we have analyzed expression and colocalization of three closely related growth factor receptors - epidermalgrowth factor (EGF) receptor, c-erbB-2, and c-erbB-3 - in human gastric cancers. Using Northern blot analysis we found a threefold overexpression of EGF receptor, a twofold overexpression of c-erbB-2, and a 1.25-fold overexpression of c-erbB-3 mRNA in gastric cancer in comparison with normal controls. Immunohistochemical analysis revealed the concomitant presence of EGF receptor, c-erbB-2, and c-erbB-3 in gastric cancer cells, indicating that these receptors may combine to contribute to the malignant transformation of cells and give gastric cancer cells a growth advantage.