Bryostatin 1 induces ubiquitin COOH-terminal hydrolase in acute lymphoblastic leukemia cells.
It has been previously reported that Bryostatin 1 (Bryo1) induces differentiation of the human acute lymphoblastic leukemia (ALL) cell line, Reh, to a monocytoid B-cell stage. In this study we demonstrate that a novel protein, ubiquitin COOH-terminal hydrolase (UCH-L1), is associated with this differentiation. Reh cells were treated with 200 nmol/l of Bryo1 for 72 h and analyzed for changes in morphology, surface immunophenotype, acid phosphatase and terminal deoxynucleotidyl transferase. Protein patterns of the parent and differentiated cells, by two-dimensional polyacrylamide gel electrophoresis (2D PAGE), were studied. Bryo1-treated cells expressed morphologic, phenotypic and enzymatic features of the monocytoid B-cell stage. The UCH-L1 enzyme (MW-pl 34-5.3) was detected by 2 D PAGE in the differentiated, but not in parent cells. The presence of UCH-L1 in the Bryo1-treated cells was further confirmed by immunoblotting of 2 D PAGE using UCH-L1 polyclonal antibody. Ubiquitin expression was studied in parent and Bryo1-treated cells and was compared with 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated cells. Both agents, TPA and Bryo1, increased the level of ubiquitin expression as detected by flow cytometry. Sodium borohydride, an inhibitor of UCH-L1, inhibited the Bryo1-induced differentiating effect on Reh cells. To date, the mechanism by which Bryo1, exerts its B-cell differentiating effect is not fully understood. This study shows that UCH-L1 expression may play a major role in Bryo1-induced differentiation in pre-B-ALL.
Mohammad
R M
RM
Division of Hematology and Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, Mich, USA.
Maki
A
A
Pettit
G R
GR
al-Katib
A M
AM
D000293:Adolescent; D000818:Animals; D054713:Bryostatins; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D015180:Electrophoresis, Gel, Two-Dimensional; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D015151:Immunoblotting; D007783:Lactones / Q000494:pharmacology*; D007945:Leukemia, Lymphoid / Q000201:enzymology* / Q000473:pathology; D018942:Macrolides; D008934:Mitogens / Q000494:pharmacology*; D011817:Rabbits; D013869:Thiolester Hydrolases / Q000096:biosynthesis* / Q000187:drug effects / Q000276:immunology; D014407:Tumor Cells, Cultured; D043222:Ubiquitin Thiolesterase
D054713:Bryostatins; D007106:Immune Sera; D007783:Lactones; D018942:Macrolides; D008934:Mitogens; C046785:bryostatin 1; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase