Characterization of the cDNA encoding human nucleophosmin and studies of its role in normal and abnormal growth

Abstract

A cDNA encoding human nucleophosmin (protein B23) was obtained by screening a human placental cDNA library in lambda gtll first with monoclonal antibody to rat nucleophosmin and then with confirmed partial cDNA of human nucleophosmin as probes. The cDNA had 1311 bp with a coding sequence encoding a protein of 294 amino acids. The identity of the cDNA was confirmed by the presence of encoded amino acid sequences identical with those determined by sequencing pure rat nucleophosmin (a total of 138 amino acids). The most striking feature of the sequence is an acidic cluster located in the middle of the molecule. The cluster consists of 26 Asp/Glu and 1 Phe and Ala. Comparison of human nucleophosmin and Xenopus nucleolar protein NO38 shows 64.3% sequence identity. The N-terminal 130 amino acids of human nucleophosmin also bear 50% identity with that of Xenopus nucleoplasmin. Northern blot analysis of rat liver total RNA with a partial nucleophosmin cDNA as probe demonstrated a homogeneous mRNA band of about 1.6 kb. Similar observations were made in hypertrophic rat liver and Novikoff hepatoma. However, the quantity of nucleophosmin mRNA is 50- and 5-fold higher in Novikoff hepatoma and hypertrophic rat liver, respectively, when compared with normal rat liver. Dot blot analysis also showed a nucleophosmin mRNA ratio of 64:5:1 in the three types of rat liver. When the protein levels were compared with Western blot immunoassays, Novikoff hepatoma showed 20 times more nucleophosmin, while only about 5 times more nucleophosmin was observed in hypertrophic rat liver than in unstimulated normal liver.

NSC348884, a nucleophosmin inhibitor disrupts oligomer formation and induces apoptosis in human cancer cells

“…Nucleophosmin is found to be more abundant in tumor and growing cells than that in normal resting cells (Feuerstein et al, 1988;Chan et al, 1989). In fact, NPM has been proposed as a tumor marker for prostate (Subong et al, 1999), colon (Nozawa et al, 1996), ovarian (Shields et al, 1997), gastric (Tanaka et al, 1992) and bladder (Yeh et al, 2006) cancers because NPM expression is markedly higher in these tumor cells than that in the corresponding normal cells.…”

Deregulation of NPM and PLZF in a variant t(5;17) case of acute promyelocytic leukemia

“…Recently, our group characterized a novel t(11;17)(q13;q21) variant APL translocation (Wells et al, 1996(Wells et al, , 1997 which resulted in the fusion of RARa to the nuclear mitotic apparatus gene, NuMA (Lydersen and Pettijohn, 1980;Sparks et al, 1993). A variant t(5;17)(q35;q21) APL translocation, which fuses RARa to the nucleophosmin gene (NPM) (Kang et al, 1974;Chan et al, 1989) has also been recently identi®ed (Redner et al, 1996). Like PML-RARa and PLZF-RARa chimeric proteins, it appears that NPM-RARa shares the ability to act as a ligand-dependent transcriptional activator of retinoic acid responsive genes, in vitro (Redner et al, 1996).…”

Apoptosis induced by the myelodysplastic syndrome-associated NPM-MLF1 chimeric protein

“…During the last decade, however, analyses of the abnormal proteins derived from chromosomal translocations have provided crucial insights into the molecular mechanisms of tumorigenesis in a variety of leukemias and lymphomas (Rabbitts, 1994;Look, 1997). It has been reported that the t(3;5)(q25.1;q34) chromosomal translocation is restricted to MDS and AML except for acute promyelocytic leukemia (Raimondi et al, 1989), and this suggests that the resultant fusion protein (NPM-MLF1) consisting of nucleophosmin (NPM) (SchmidtZachmann and Franke, 1988;Chan et al, 1989) and a novel cytoplasmic protein, myelodysplasia/myeloid leukemia factor 1 (MLF1) (Yoneda-Kato et al, 1996), is involved in dysregulation of pluripotent progenitor cells and plays a role in ine ective hematopoiesis and/or multi-step transformation into overt leukemia.…”