Expression of the imprinted tumour-suppressor gene H19 is tightly regulated during normal haematopoiesis and is reduced in haematopoietic precursors of patients with the myeloproliferative disease polycythaemia vera

cDNA subtraction was employed to uncover differences in gene expression bet ween myeloproliferative polycythaemia vera (PV) and normal haematopoietic p recursors, Following cDNA subtraction using mRNAs isolated from PV and norm al CD34+/CD33- bone-marrow cells, expression of the tumour suppressor H19 w as found to be lowe or absent in the PV sample, Low levels of H19 expressio n in PV patients were confirmed by in situ hybridization, Using semiquantit ative reverse transcriptase-polymerase chain reaction (RT-PCR) to examine e xpression in the pluripotent haematopoietic cell Line FDCP-mix and single b one-marrow precursors, unambiguous IGF2 and H19 expression was demonstrated in normal haematopoietic precursors. Examination of individual bone-marrow precursors revealed that all IGF2-expressing haematopoietic precursors als o co-expressed H19, indicating that H19 and IGF2 may be co-ordinately regul ated during haematopoiesis. Analysis of FDCP-mix undergoing differentiation and single pluripotent and committed bone-marrow precursors revealed that the pattern of H19 expression coincided with the commitment to a single lin eage. Taken together, these observations demonstrate that H19 and IGF2 are specifically expressed during haematopoiesis and that low levels of H19 exp ression are associated with PV and may contribute to the pathology of the d isease. Copyright (C) 2000 John Wiley & Sons, Ltd.