THE PRODUCT OF THE IMPRINTED H19 GENE IS AN ONCOFETAL RNA

Aims/background-The H19 gene is an imprinted, maternally expressed gen e in humans. It is tightly linked and coregulated with the imprinted, paternally expressed gene of insulin-like growth factor 2. The H19 gen e product is not translated into protein and functions as an RNA molec ule. Although its role has been investigated for more than a decade, i ts biological function is still not understood fully. H19 is abundantl y expressed in many tissues from early stages of embryogenesis through fetal life, and is down regulated postnatally. It is also expressed i n certain childhood and adult tumours. This study was designed to scre en the expression of H19 in human cancer and its relation to the expre ssion of H19 in the fetus. Methods-Using in situ hybridisation with a [S-35] labelled probe, H19 mRNA was detected in paraffin wax sections of fetal tissues from the first and second trimesters of pregnancy and of a large array of human adult and childhood tumours arising from th ese tissues. Results-The H19 gene is expressed in tumours arising from tissues which express this gene in fetal life. Its expression in the fetus and in cancer is closely linked with tissue differentiation. Con clusions-Based on these and previous data, H19 is neither a tumour sup pressor gene nor an oncogene. Its product is an oncofetal RNA. The pot ential use of this RNA as a tumour marker should be evaluated.