NUCLEAR AND CYTOPLASMIC EXPRESSIONS OF THE CARBOHYDRATE-BINDING PROTEIN CBP70 IN TUMORAL OR HEALTHY CELLS OF THE MACROPHAGIC LINEAGE

The expression of the carbohydrate-binding protein CBP70 was analyzed in undifferentiated HL60 cells, HL60 cells differentiated into monocyt es/macrophages or granulocytes, healthy monocytes and in vitro monocyt e-derived macrophages (MDM) using an anti-CBP70 serum. This study was performed by immunoblotting analysis of nuclear and cytoplasmic extrac ts before and after N-acetylglucosamine affinity chromatography and by indirect immunofluorescence microscopy. The results of this study sho w, for the fr st time, that CBP70 is expressed in the nucleus and the cytoplasm of healthy or leukemic cells of the macrophagic lineage. How ever, striking differences were observed depending upon the leukemic o r normal state of cells and cell differentiation. Indeed, the level of expression and the intracellular distribution of CBP70 were found to be different in undifferentiated HL60 cells and monocytes/macrophages differentiated from these cells. Major differences were also observed according to whether macrophages differentiated from leukemic HL60 cel ls or healthy monocytes. Thus, the total cellular expression of CBP70 was markedly lower in MDM than in HL60-derived macrophages and the int racellular distribution of the protein was different. Nevertheless, in both cases, the total cellular expression of CBP70 was enhanced durin g cell differentiation. Another important result is the finding that C BP70 behaviour was totally different when HL60 cells were induced to d ifferentiate into macrophages or granulocytes. These data could theref ore suggest that CBP70 is involved in phagocytic cell differentiation. Moreover, we show that an additional 60 kDa polypeptide (p60), recogn ized by the anti-CBP70 serum, is expressed in HL60 cells differentiate d into macrophages or granulocytes as well as in healthy monocytes or MDM but not expressed in undifferentiated HL60 cells. Although CBP70 a nd p60 appeared to be closely related polypeptides, their relationship remains to be precised. These findings are discussed with regard to d ata available on galectin-3. (C) 1996 Wiley-Liss, Inc.