An intronless homolog of human proto-oncogene hPTTG is expressed in pituitary tumors: Evidence for hPTTG family

A novel proto oncogene, PTTG (Pituitary Tumor Transforming Gene), was isola ted in our laboratory by virtue of its increased expression in rat pituitar y tumor cell lines. Cells which overexpress human or rat PTTG form tumors i n athymic mice, hPTTG is highly expressed in cancer cell Lines, pituitary a denomas and in normal testis, suggesting that hPTTG protein has different t issue-specific interactions in normal cells and in cancer. Alternatively, d ifferent hPTTG gene family members may be functional in normal development and in tumorigenesis. While mapping the chromosomal location of hPTTG to 5q 33, we discovered a second gene, hPTTG2, which is intronless and maps to ch romosome 4p12. Using gene-specific oligonucleotide hybridization in a PCR-E LISA assay, we determined that hPTTG2 is expressed in both normal and tumor ous pituitary. However, high levels of hPTTG mRNA in cancer cell lines are due to increased expression of hPTTG1. Thus, this family of proto-oncogenes appears to differentially participate in tumor-specific pathogenesis.