Transactivation of the IGFBP-2 promoter in human tumor cell lines.

Many cancers produce high amounts of the insulin-like growth factor binding protein (IGFBP)-2, which can influence the tumorigenicity and growth of tumor cells. In order to study the possible cause of elevated expression of IGFBP-2 in tumors, we investigated the transcriptional regulation by IGF of a 633-bp fragment of the human IGFBP-2 promoter in a transiently transfected choriocarcinoma (JAR) and a leukemic T-cell line (Molt-4) that express IGFBP-2 highly, and in a leukemic B-cell line (Raji) that expresses little IGFBP-2. Strong basal promoter activity, i.