The natural product avrainvillamide binds to the oncoprotein nucleophosmin.

Abstract

Here we present evidence that (+)-avrainvillamide, a naturally occurring alkaloid with antiproliferative effects, binds to the nuclear chaperone nucleophosmin, a proposed oncogenic protein that is overexpressed in many different human tumors. Among other effects, nucleophosmin is known to regulate the tumor suppressor protein p53. A synthetic biotin-avrainvillamide conjugate, nearly equipotent to the natural product in inhibiting the growth of cultured T-47D cells, was used for affinity-isolation of a protein identified as nucleophosmin by MS sequencing and Western-blotting. Affinity-isolation of nucleophosmin was inhibited in the presence of iodoacetamide (10 mM), free (+)-avrainvillamide (100 microM), and a series of closely related structural analogues of (+)-avrainvillamide, the latter with inhibitory effects that appear to correlate with measured growth-inhibitory potencies. Using fluorescence microscopy, a synthetic dansyl-avrainvillamide conjugate was observed to localize within the nucleoli and the cytosol of treated cancer cells. Site-directed mutagenesis of each of the three cysteine residues of a truncated nucleophosmin coexpressed with native nucleophosmin in COS-7 cells revealed that the mutation cys275 --> ala275 effectively and uniquely reduced affinity-isolation of the truncated protein, suggesting that avrainvillamide targets cys275 of nucleophosmin. Finally, we show that treatment of adhered LNCaP or T-47D cells with (+)-avrainvillamide leads to an increase in cellular p53 concentrations, and that siRNA-promoted depletion of nucleophosmin in a population of HeLa S3 cells leads to increased sensitivity of that population toward apoptotic death upon treatment with (+)-avrainvillamide. Although potentially desirable as lead compounds for the development of novel anticancer therapies, nonpeptidic, synthetic small molecules that bind to nucleophosmin have not been described, prior to this report.

• Authors: Jeremy E Wulff, Romain Siegrist, Andrew G Myers
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 129 Issue 46 Pg. 14444-51 (Nov 21 2007) ISSN: 0002-7863 [Print] United States
• PMID: 17958425 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• Biological Products
• Indoles
• NPM1 protein, human
• Nuclear Proteins
• Oncogene Proteins
• avrainvillamide
• Nucleophosmin
• Biotin
• Cysteine
• Alanine

Topics

• Alanine (chemistry, metabolism)
• Animals
• Antineoplastic Agents (pharmacology)
• Binding Sites
• Biological Products (pharmacology)
• Biotin (chemistry, metabolism)
• Blotting, Western
• COS Cells
• Chlorocebus aethiops
• Cysteine (chemistry, metabolism)
• HeLa Cells
• Humans
• Indoles (chemistry, metabolism, pharmacology)
• Microscopy, Fluorescence
• Nuclear Proteins (chemistry, metabolism)
• Nucleophosmin
• Oncogene Proteins (chemistry, metabolism)
• Tumor Cells, Cultured (drug effects)