Proliferative involvement of ENX-1, a putative human polycomb group gene, in haematopoietic cells.

Homeobox genes have important roles in haematopoiesis and are regulated in an activated state by the trithorax group (trxG) of genes. In a repressed state, they are regulated by the Polycomb group (PcG) of genes. ENX-1, a putative human PcG gene product, interacts with the proto-oncogene product Vav. We report an investigation of the role of ENX-1 in human haematopoiesis. CD34+ cells mobilized to peripheral blood strongly expressed ENX-1. When stimulated to proliferate, both T and B lymphocytes rapidly up-regulated ENX-1. ENX-1 was expressed in all cell lines of the various lineages examined. When HL-60 cells were differentiated to mature granulocytes with all-trans retinoic acid, ENX-1 was down-regulated. Moreover, ENX-1 antisense oligodeoxynucleotide suppressed DNA synthesis in HL-60 cells. Our data indicate that ENX-1 is involved in the proliferation of both normal and malignant haematopoietic cells.