Occurrence of particular isoenzymes in fresh and cultured leukemia-lymphoma cells: II. Hexosaminidase I isoenzyme

Abstract

The isoenzyme profiles of hexosaminidase (N-acetyl-beta-D-glucosaminidase) were analyzed by isoelectric focusing on horizontal polyacrylamide thin-layer gel with special emphasis on the intermediate isoenzyme (Hex I). The expression of Hex I was examined in 87 leukemia-lymphoma cell lines, in 14 B-lymphoblastoid cell lines, in 441 cases of leukemia-lymphoma (specimens containing 80% or more tumor cells), in 22 leukemia cell lines and in 14 cases of leukemia that had been treated with phorbolesters (TPA) for induction of differentiation, and in the mononuclear cell preparations separated from peripheral blood, lymph node, thymus, bone marrow, tonsil, liver, and spleen specimens from normal donors. Hex I was detected in the leukemia cell lines arrested at early, immature or at late, mature stages of B- and T-cell differentiation, but not in cell lines blocked at intermediate stages of maturation. Most myelomonocytic leukemia cell lines and the erythroleukemia cell lines showed Hex I, whereas the B-lymphoblastoid cell lines were negative for this marker. During induction of differentiation, the expression of Hex I was lost in 13 of 15 leukemia cell lines that were originally Hex I-positive. Among the panel of the "fresh" leukemia-lymphoma cells, Hex I was found predominantly in cases of acute lymphoblastic leukemia and acute myeloblastic/monoblastic leukemia, but rarely or not at all in the mature T-, B- or myeloid malignancies. However, two out of two cases of multiple myeloma were Hex I-positive, and the Hex I expression could be induced by TPA in three of six B-cell chronic lymphocytic leukemia cases. Chronic myelocytic leukemia cells remained Hex I-negative during induction of differentiation. Hex I-positivity was not detected in the cell preparations from normal tissues, and peripheral blood indicating that the normal cellular counterpart of the Hex I-positive tumor cells are present at only low percentages within the respective cell populations. It is suggested that Hex I is a marker of early lymphoid and myeloid hematopoiesis that is no longer expressed in intermediate stages of lymphoid differentiation and in later or terminal stages of myeloid differentiation, but that is again detectable in terminally differentiated B-cells. Further studies will focus on identification and isolation of normal Hex I-positive cells.

An enzyme with properties similar to those of β-N-acetylhexosaminidase S is expressed in the promyelocytic cell line HL-60

“…The promyelocytic cell line HL-60 expresses a stable pattern of fl-N-acetylhexosaminidase isoenzymes when analysed by isoelectric focusing Drexler et al, 1986) or chromatofocusing (Orlacchio et al 1986b). We have previously described the presence of a particular type of fl-Nacetylhexosaminidase in leukaemic cells of lymphoid and myeloid origins, distinguished by its behaviour on PBA chromatography, that is absent from normal lymphocytes and myelocytes and is distinct from fl-N-acetylhexosaminidases A and B (Orlacchio et al, 1984).…”

“…One possibility is that the enzyme is unrelated to the A and B forms, but this seems unlikely because anti-(fl-Nacetylhexosaminidase a-subunit) serum was able to precipitate 90 % of the 'extra' form. Altered behaviour of f-Nacetylhexosaminidase isoenzymes in leukaemic cells has been ascribed to post-translational modifications involving glycosylation (Swallow et al, 1977;Dewji et al, 1981;Drexler et al, 1986). At first sight this would appear to be the case for the fl-N-acetylhexosaminidase of HL-60 cells because of their behaviour on Matrex gel chromatography.…”

Intermediate forms of human β-N-acetylhexosaminidase lack activity towards 4-methylumbelliferyl β-N-acetylglucosaminide 6-sulphate

“…Although the intermediate forms account for only a small proportion of the total activity in normal tissues and body fluids, they are increased very greatly in maternal serum during pregnancy, when fl-N-acetylhexosaminidase P becomes the major form (Stirling, 1971), and in lymphocytes from patients with common acute lymphoblastic leukaemia, which is characterized by an increase in ,-N-acetylhexosaminidase 12 (Ellis et al, 1978). The presence of 8l-N-acetylhexosaminidase I2 in leukaemic cells has been used as a marker to define the cALL (common acute lymphoblastic leukaemia) phenotype (Greaves, 1979), and the intermediate forms detected by isoelectric focusing in polyacrylamide gels have been regarded as markers of early haemopoiesis in the lymphoid and myeloid systems and of terminal lymphoid development (Drexler et al, 1986).…”

Defective plateletβ-N-acetyl hexosaminidase content and release in chronic myeloproliferative disorders

“…Lysosomal Hex has previously been found to be altered in leukemic cells at various stages of differentiation along the myeloid and lymphoid pathway [37][38][39]. In normal human blood cells, including platelets, Hex is present as two major isoenzymes, Hex A and Hex B, consisting ofand -dimers, respectively, both involved in the degradation of terminal -glycosidically bound N-acetylhexosamine residues from several glycoconjugates [40].…”