Autocrine and possible intracrine regulation of HL-60 cell proliferation by macrophage colony-stimulating factor.

The abnormal expression of macrophage colony stimulating factor (M-CSF) isoforms, i.e. membrane bound M-CSF (m-M-CSF) and intracellular M-CSF (c-M-CSF), and their receptor were reported in some leukemia and tumor cells. Furthermore, the nuclear localization of them may be related to poor prognosis and metastasis, while the mechanism is uncertain. We previously reported that m-M-CSF and its receptor played auto-juxtacrine and adhesion molecule role in human leukemia cell line J6-1. In this paper, we show that HL-60 cells highly express M-CSF and its receptor. The localization of positive reactions was mainly in cytoplasma and nuclear in HL-60 cells. In cytoplasma and nuclear, three isoforms of M-CSF were found with molecular weight (MW) of 20, 16 and 14 kDa, while one type of m-CSF receptor (M-CSFR) was discovered with MW of 120 kDa. Immunoprecipitation assay showed that these ligands could exist separately or binding with their receptor. Monoclonal antibody (McAb) against M-CSF and anti-sense oligodeoxynucleotides (ASON) blocking M-CSF expression inhibited the proliferation of HL-60 cells. McAb and ASON regulated the expression of cyclin D1/E, CDK2/4 and p16. Simultaneous administration of both McAb and ASON inhibited the proliferation of HL-60 cells and modulate the expression of cyclins at greater degrees. Our results suggested an autocrine and possible an intracrine loop of M-CSF/M-CSFR in HL-60 cells.