CONSTRUCTION OF AN ECOTROPIC RETROVIRAL VECTOR EXPRESSING HUMAN INSULIN-LIKE GROWTH FACTOR-I

There is increasing evidence that IGF-I plays an autocrine role in a w ide range of human tumours, including, in particular, adenomas of the thyroid epithelium. To investigate this further, we set out to generat e a retrovirus vector which would permit experimental manipulation of the expression of IGF-I in normal and neoplastic epithelial cells. We describe here the construction and validation of a high-titre ecotropi c vector which transduces stable expression and secretion of human IGF -IA, as shown by analysis of mRNA and conditioned medium from rodent e pithelial target cells. This vector should be a useful tool for assess ing the contribution of abnormal IGF-I expression to the neoplastic ph enotype.