Metastasis suppressor function of NM23-H1 requires its 3'-5' exonuclease activity.

Abstract

The metastasis suppressor NM23-H1 possesses 3 enzymatic activities in vitro, a nucleoside diphosphate kinase (NDPK), a protein histidine kinase and a more recently characterized 3'-5' exonuclease. Although the histidine kinase has been implicated in suppression of motility in breast carcinoma cell lines, potential relevance of the NDPK and 3'-5' exonuclease to metastasis suppressor function has not been addressed in detail. To this end, site-directed mutagenesis and biochemical analyses of bacterially expressed mutant NM23-H1 proteins have identified mutations that disrupt the 3'-5' exonuclease alone (Glu(5) to Ala, or E(5) A), the NDPK and histidine kinase activities tandemly (Y(52) A, H(118) F) or all 3 activities simultaneously (K(12) Q). Although forced expression of NM23-H1 potently suppressed spontaneous lung metastasis of subcutaneous tumor explants derived from the human melanoma cell line 1205LU, no significant metastasis suppressor activity was obtained with the exonuclease-deficient variants E(5) A and K(12) Q. The H(118) F mutant, which lacked both the NDPK and histidine kinase while retaining the 3'-5' exonuclease, also exhibited compromised suppressor activity. In contrast, each mutant retained the ability to suppress motility and invasive characteristics of 1205LU cells in culture, indicating that the NM23-H1 molecule possesses an additional activity(s) mediating these suppressor functions. These studies provide the first demonstration that the 3'-5' exonuclease activity of NM23-H1 is necessary for metastasis suppressor function and further indicate cooperativity of the 3 enzymatic activities of the molecule on suppression of the metastatic process.

• Authors: Qingbei Zhang, Joseph R McCorkle, Marian Novak, Mengmeng Yang, David M Kaetzel
• Journal: International journal of cancer (Int J Cancer) Vol. 128 Issue 1 Pg. 40-50 (Jan 01 2011) ISSN: 1097-0215 [Electronic] United States
• PMID: 20209495 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2010 UICC.

Chemical References

• NM23 Nucleoside Diphosphate Kinases
• Glutamic Acid
• Histidine
• Protein Kinases
• Histidine Kinase
• Exonucleases
• Lysine

Topics

• Amino Acid Sequence
• Animals
• Blotting, Western
• Cell Line, Tumor
• Cell Movement
• Cell Proliferation
• Exonucleases (chemistry, genetics, metabolism)
• Female
• Glutamic Acid (genetics, metabolism)
• Histidine (genetics, metabolism)
• Histidine Kinase
• Humans
• Lung Neoplasms (enzymology, genetics, secondary)
• Lysine (genetics, metabolism)
• Melanoma, Experimental (enzymology, genetics, pathology)
• Mice
• Mice, Nude
• Models, Molecular
• Molecular Sequence Data
• Mutagenesis, Site-Directed
• Mutation, Missense
• NM23 Nucleoside Diphosphate Kinases (chemistry, genetics, metabolism)
• Protein Conformation
• Protein Kinases (chemistry, genetics, metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Transplantation, Heterologous