Endogenous tetrapeptide from neuroblastoma and new-born pig brain inhibits neuroblastoma cell growth in vitro

Neuroblastoma, the most frequent malignant tumour in neonates and young children, has an unusual clinical behaviour, age being the most important single factor. This could indicate that some growth-regulating mechanism in lost, or changed, during the first years of life. In search for possible growth-modifying factors, we identified a tetrapeptide, acetyl-Asp-Gln-Tyr-GlyNH2, in extracts of neuroblastoma tissue, in neuroblastoma cell cultures and in new-born pig brain tissue. The purified native peptide as well as a synthetic peptide with the same structure decreases in vitro growth of neuroblastoma cells at a restricted, low (picomolar) range. The structure of the peptide as well as its dose-response characteristics, indicates that it belongs to a group of endogenous growth-modifying oligopeptides that previously have been isolated from other organs and tissues. A possible role for the new peptide in clinical medicine is discussed.