Abstract
In renal cell carcinoma, transglutaminase 2 (TGase 2) crosslinks p53 in autophagosomes, resulting in p53 depletion and the tumor's evasion of apoptosis. Inhibition of TGase 2 stabilizes p53 and induces tumor cells to enter apoptosis. This study explored the mechanism of TGase 2-dependent p53 degradation. We found that TGase 2 competes with human double minute 2 homolog (HDM2) for binding to p53; promotes autophagy-dependent p53 degradation in renal cell carcinoma (RCC) cell lines under starvation; and binds to p53 and p62 simultaneously without ubiquitin-dependent recognition of p62. The bound complex does not have crosslinking activity. A binding assay using a series of deletion mutants of p62, p53 and TGase 2 revealed that the PB1 (Phox and Bem1p-1) domain of p62 (residues 85-110) directly interacts with the β-barrel domains of TGase 2 (residues 592-687), whereas the HDM2-binding domain (transactivation domain, residues 15-26) of p53 interacts with the N terminus of TGase 2 (residues 1-139). In addition to the increase in p53 stability due to TGase 2 inhibition, the administration of a DNA-damaging anti-cancer drug such as doxorubicin-induced apoptosis in RCC cell lines and synergistically reduced tumor volume in a xenograft model. Combination therapy with a TGase 2 inhibitor and a DNA-damaging agent may represent an effective therapeutic approach for treating RCC.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antibiotics, Antineoplastic / pharmacology
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Antibiotics, Antineoplastic / therapeutic use
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Apoptosis* / drug effects
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Autophagy / drug effects
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Carcinoma, Renal Cell / drug therapy
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Carcinoma, Renal Cell / metabolism
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Carcinoma, Renal Cell / pathology
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Cell Line, Tumor
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Chloroquine / pharmacology
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DNA Damage / drug effects
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Doxorubicin / pharmacology
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Doxorubicin / therapeutic use
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Female
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GTP-Binding Proteins / antagonists & inhibitors
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism*
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Humans
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Kidney Neoplasms / drug therapy
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Kidney Neoplasms / metabolism
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Kidney Neoplasms / pathology
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Mice
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Mice, Inbred BALB C
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Mice, Nude
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Phosphorylation / drug effects
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Protein Binding
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Protein Glutamine gamma Glutamyltransferase 2
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Proto-Oncogene Proteins c-mdm2 / antagonists & inhibitors
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Proto-Oncogene Proteins c-mdm2 / genetics
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Proto-Oncogene Proteins c-mdm2 / metabolism
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Pyrazines / pharmacology
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Pyrazines / therapeutic use
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RNA-Binding Proteins / chemistry
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RNA-Binding Proteins / metabolism
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Transglutaminases / antagonists & inhibitors
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Transglutaminases / genetics
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Transglutaminases / metabolism*
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Tumor Suppressor Protein p53 / chemistry
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Tumor Suppressor Protein p53 / genetics*
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Tumor Suppressor Protein p53 / metabolism
Substances
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3-(phenylethynyl)-2-(2-(pyridin-2-yl)ethoxy)pyrido(3,2-b)pyrazine
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Antibiotics, Antineoplastic
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P62 protein, human
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Pyrazines
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RNA-Binding Proteins
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Tumor Suppressor Protein p53
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Doxorubicin
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Chloroquine
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Protein Glutamine gamma Glutamyltransferase 2
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Transglutaminases
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MDM2 protein, human
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Proto-Oncogene Proteins c-mdm2
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GTP-Binding Proteins