ENHANCED EXPRESSION OF ALPHA(V) INTEGRIN SUBUNIT AND OSTEOPONTIN DURING DIFFERENTIATION OF HL-60 CELLS ALONG THE MONOCYTIC PATHWAY

HL-60 cells, a promyelocytic leukemic cell line, provide a good model for studying the role of adhesion molecules and associated receptors i nvolved in cell differentiation. When exposed to factors such as phorb ol esters, these cells grown in suspension differentiate into monocyte s and adhere to tissue culture dishes. In this study we showed that HL -60 cells exposed to phorbol esters express osteopontin (OPN), a cell adhesion molecule linked with osteoclast function. Moreover, the timed expression of OPN, in phorbol ester treated cells, was linked to incr eased cell adhesion. Subsequent to the expression of OPN, an increase in mRNA levels for alpha(V) integrin subunit was observed. The alpha(V ) beta(3) integrin, a cell surface receptor found in high concentratio ns in osteoclasts, is considered to be a receptor for OPN. Furthermore , during differentiation we detected an increase in two cell surface m arkers specific for osteoclasts, 75B and 121F. This is the first repor t to demonstrate expression of OPN during differentiation of HL-60 cel ls, indicating that HL-60 cells can be used as a tool to enhance our u nderstanding as to the role of OPN in cell differentiation. (C) 1995 A cademic Press, Inc.