Recombinant, refolded tetrameric p53 and gonadotropin-releasing hormone-p53 slow proliferation and induce apoptosis in p53-deficient cancer cells.

Abstract

The p53 tumor suppressor is mutated in over 50% of human cancers. Mutations resulting in amino acid changes within p53 result in a loss of activity and consequent changes in expression of genes that regulate DNA repair and cell cycle progression. Replacement of p53 using protein therapy would restore p53 function in p53-deficient tumor cells, with a consequence of tumor cell death and tumor regression. p53 functions in a tetrameric form in vivo. Here, we refolded a wild-type, full-length p53 from inclusion bodies expressed in Escherichia coli as a stable tetramer. The tetrameric p53 binds to p53-specific DNA and, when transformed into a p53-deficient cancer cell line, induced apoptosis of the transformed cells. Next, using the same expression and refolding technology, we produced a stable tetramer of recombinant gonadotropin-releasing hormone-p53 fusion protein (GnRH-p53), which traverses the plasma membrane, slows proliferation, and induces apoptosis in p53-deficient, GnRH-receptor-expressing cancer cell lines. In addition, we showed a time-dependent binding and internalization of GnRH-p53 to a receptor-expressing cell line. We conclude that the GnRH-p53 fusion strategy may provide a basis for constructing an effective cancer therapeutic for patients with tumors in GnRH-receptor-positive tissue types.

• Authors: Michelle Lafevre-Bernt, Shili Wu, Xinli Lin
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 7 Issue 6 Pg. 1420-9 (Jun 2008) ISSN: 1535-7163 [Print] United States
• PMID: 18566214 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Nucleosomes
• Recombinant Fusion Proteins
• Tumor Suppressor Protein p53
• Gonadotropin-Releasing Hormone

Topics

• Apoptosis
• Biological Assay
• Cell Line, Tumor
• Cell Proliferation
• Endocytosis
• Gonadotropin-Releasing Hormone (metabolism)
• Humans
• Immunohistochemistry
• In Situ Nick-End Labeling
• Neoplasms (pathology)
• Nucleosomes (metabolism)
• Protein Folding
• Protein Structure, Quaternary
• Protein Transport
• Recombinant Fusion Proteins (isolation & purification, metabolism)
• Thermodynamics
• Tumor Suppressor Protein p53 (chemistry, deficiency, isolation & purification, metabolism)