HIGH EXPRESSION OF UDP-N-ACETYLGLUCOSAMINE - BETA-D MANNOSIDE BETA-1,4-N-ACETYLGLUCOSAMINYLTRANSFERASE-III (GNT-III) IN CHRONIC MYELOGENOUSLEUKEMIA IN BLAST CRISIS

The activity and mRNA expression of UDP-N-acetylglucosamine: beta-D ma nnoside beta-1,4-N-acetylglucosaminyl transferase III (GnT-III: EC 2.4 .1.144) were investigated in hematological malignancies. GnT-III activ ity was elevated in patients with chronic myelogenous leukemia(CML) in blast crisis and patients with multiple myeloma (MM), as compared to normal healthy subjects and patients with other hematological malignan cies including CML in chronic phase. The GnT-III transcript was the sa me sire in leukemic cells from various hematological diseases and cell lines, while expression of the transcript was not found to correlate significantly with enzyme activity, implying that post-translational m odification might regulate the activity of GnT-III. Southern-blot anal ysis showed no significant variation in the structure and position of the GnT-III genome, indicating that the gene is present as a single co py without isoforms. Furthermore, analyses by immunoprecipitation and Western blot revealed that high GnT-III activity in KU8 IZ cell, a CML cell line, resulted in an increase in E(4)-PHA binding to CD45, a maj or surface glycoprotein of the leukocyte, indicating that more bisecti ng GlcNAc was added to CD45 catalyzed by elevated GnT-III.(C) 1995 Wil ey-Liss, Inc.