Expression of translation initiation factor eIF-2α is increased in benign and malignant melanocytic and colonic epithelial neoplasms

BACKGROUND. Stimulation of resting cells by growth factors leads to an increase in the rate of protein synthesis, which is necessary for cell growth and division. Translation initiation factor eIF-2α is one of the key translation factors mediating the effects of growth factors on protein synthesis. In normal cells, expression of eIF-2α is increased transiently, but its levels are elevated constitutively in oncogene-transformed cells. Overexpression of constitutively active eIF-2α in rodent cells makes them tumorigenic. In this article, the authors report their findings on the increased expression of eIF-2α in human benign and malignant neoplasms originating from melanocytes and colonic epithelium. METHODS. Immunohistochemistry was used to analyze the expression of eIF-2α, eIF-4E, and cyclin D1 in melanocytic nevi and melanomas and the expression of eIF-2α in colonic adenomas and carcinomas. RESULTS. The authors found that the expression of eIF-2α was increased markedly in both benign and malignant neoplasms of melanocytes and colonic epithelium. CONCLUSIONS. Increased expression of eIF-2α took place in both benign and malignant neoplasms of melanocytes and colonic epithelium. These findings suggest that elevated expression of this translation initiation factor may contribute to tumor initiation and progression but that it is not sufficient for establishing a malignant phenotype in the tumors analyzed in this study.