CD34+ cells from AML with mutated NPM1 harbor cytoplasmic mutated nucleophosmin and generate leukemia in immunocompromised mice.

Abstract

Acute myeloid leukemia (AML) with mutated NPM1 shows distinctive biologic and clinical features, including absent/low CD34 expression, the significance of which remains unclear. Therefore, we analyzed CD34(+) cells from 41 NPM1-mutated AML. At flow cytometry, 31 of 41 samples contained less than 10% cells showing low intensity CD34 positivity and variable expression of CD38. Mutational analysis and/or Western blotting of purified CD34(+) cells from 17 patients revealed NPM1-mutated gene and/or protein in all. Immunohistochemistry of trephine bone marrow biopsies and/or flow cytometry proved CD34(+) leukemia cells from NPM1-mutated AML had aberrant nucleophosmin expression in cytoplasm. NPM1-mutated gene and/or protein was also confirmed in a CD34(+) subfraction exhibiting the phenotype (CD34(+)/CD38(-)/CD123(+)/CD33(+)/CD90(-)) of leukemic stem cells. When transplanted into immunocompromised mice, CD34(+) cells generated a leukemia recapitulating, both morphologically and immunohistochemically (aberrant cytoplasmic nucleophosmin, CD34 negativity), the original patient's disease. These results indicate that the CD34(+) fraction in NPM1-mutated AML belongs to the leukemic clone and contains NPM1-mutated cells exhibiting properties typical of leukemia-initiating cells. CD34(-) cells from few cases (2/15) also showed significant leukemia-initiating cell potential in immunocompromised mice. This study provides further evidence that NPM1 mutation is a founder genetic lesion and has potential implications for the cell-of-origin and targeted therapy of NPM1-mutated AML.

• Authors: Maria Paola Martelli, Valentina Pettirossi, Christian Thiede, Elisabetta Bonifacio, Federica Mezzasoma, Debora Cecchini, Roberta Pacini, Alessia Tabarrini, Raffaella Ciurnelli, Ilaria Gionfriddo, Nicla Manes, Roberta Rossi, Linda Giunchi, Uta Oelschlägel, Lorenzo Brunetti, Marica Gemei, Mario Delia, Giorgina Specchia, Arcangelo Liso, Mauro Di Ianni, Francesco Di Raimondo, Franca Falzetti, Luigi Del Vecchio, Massimo F Martelli, Brunangelo Falini
• Journal: Blood (Blood) Vol. 116 Issue 19 Pg. 3907-22 (Nov 11 2010) ISSN: 1528-0020 [Electronic] United States
• PMID: 20634376 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antigens, CD34
• Membrane Glycoproteins
• Mutant Proteins
• NPM1 protein, human
• Npm1 protein, mouse
• Nuclear Proteins
• Nucleophosmin
• CD38 protein, human
• ADP-ribosyl Cyclase 1

Topics

• ADP-ribosyl Cyclase 1 (metabolism)
• Animals
• Antigens, CD34 (metabolism)
• Cytoplasm (metabolism)
• Humans
• Immunophenotyping
• Leukemia, Myeloid, Acute (genetics, immunology, metabolism, pathology)
• Membrane Glycoproteins (metabolism)
• Mice
• Mice, Inbred NOD
• Mice, SCID
• Mutant Proteins (genetics, metabolism)
• Neoplasm Transplantation
• Nuclear Proteins (genetics, metabolism)
• Nucleophosmin
• Transplantation, Heterologous