Immunohistochemistry predicts nucleophosmin (NPM) mutations in acute myeloid leukemia.
Nucleophosmin (NPM) exon-12 mutations occur in 50% to 60% of adult acute myeloid leukemia (AML) with normal karyotype and are predictors of favorable prognosis. We evaluated bone marrow or peripheral blood samples from 450 adult patients with AML of the GIMEMA (Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto)/AML12 EORTC (European Organization for Research and Treatment of Cancer) trial to (1) search for new exon-12 NPM mutations; (2) determine whether NPM immunostaining on paraffin-embedded biopsies predicts NPM mutations; and (3) investigate altered nucleocytoplasmic NPM traffic in primary AML cells. Fourteen NPM mutations, including 8 new variants, were identified. All 200 AML cases expressing cytoplasmic NPM (NPMc(+) AML) carried NPM mutations. None of the 250 cases with nucleus-restricted NPM (NPMc(-) AML) was mutated. At the C-terminus, NPM leukemic mutants carried mutations of only tryptophan 290 or of both tryptophans 288 and 290 and a new nuclear export signal (NES) motif, which appear to underlie their nuclear export. The specific Crm1/exportin-1 inhibitor leptomycin-B relocated NPM mutants from cytoplasm to nucleus of primary NPMc(+) AML cells, demonstrating that nuclear export is NES dependent. NPM mutants bound and recruited wild-type NPM into leukemic cell cytoplasm. Because alterations at C-terminus of leukemic NPM mutants are similar, immunohistochemistry detects all exon-12 NPM mutations and is a valuable, inexpensive tool in the diagnostic-prognostic work-up of patients with AML with normal karyotype.
Falini
Brunangelo
B
Institute of Hematology, Policlinico Monteluce, 06122 Perugia, Italy. faliniem@unipg.it
Martelli
Maria Paola
MP
Bolli
Niccolò
N
Bonasso
Rossella
R
Ghia
Emanuela
E
Pallotta
Maria Teresa
MT
Diverio
Daniela
D
Nicoletti
Ildo
I
Pacini
Roberta
R
Tabarrini
Alessia
A
Galletti
Barbara Verducci
BV
Mannucci
Roberta
R
Roti
Giovanni
G
Rosati
Roberto
R
Specchia
Giorgina
G
Liso
Arcangelo
A
Tiacci
Enrico
E
Alcalay
Myriam
M
Luzi
Lucilla
L
Volorio
Sara
S
Bernard
Loris
L
Guarini
Anna
A
Amadori
Sergio
S
Mandelli
Franco
F
Pane
Fabrizio
F
Lo-Coco
Francesco
F
Saglio
Giuseppe
G
Pelicci
Pier-Giuseppe
PG
Martelli
Massimo F
MF
Mecucci
Cristina
C
D021581:Active Transport, Cell Nucleus; D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D003593:Cytoplasm / Q000378:metabolism; D004273:DNA, Neoplasm / Q000235:genetics; D005091:Exons; D006801:Humans; D007150:Immunohistochemistry; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D009154:Mutation; D049790:Nuclear Export Signals / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000090243:Nucleophosmin; D014364:Tryptophan / Q000235:genetics
D004273:DNA, Neoplasm; C000716967:NPM1 protein, human; D049790:Nuclear Export Signals; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D014364:Tryptophan