A Novel p53 Mutant Found in Iatrogenic Urothelial Cancers Is Dysfunctional and Can Be Rescued by a Second-site Global Suppressor Mutation

• Published in: The Journal of biological chemistry Vol. 288; no. 23; pp. 16704 - 16714
• Main Authors: Odell, Adam F., Odell, Luke R., Askham, Jon M., Alogheli, Hiba, Ponnambalam, Sreenivasan, Hollstein, Monica
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.06.2013; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Substitution; Animals; Aristolochic Acids - adverse effects; Aristolochic Acids - pharmacology; Biologi med inriktning mot molekylär cellbiologi; Biology with specialization in Molecular Cell Biology; Biomarkers; Biomarkers, Tumor; Cancer Biology; Cell Line, Transformed; Cellular Senescence; Humans; Iatrogenic Disease; Mice; Molecular Bases of Disease; Molecular Cell Biology; Mouse Genetics; Mutagenesis Mechanisms; Mutagens - adverse effects; Mutagens - pharmacology; Mutation, Missense; Plant Preparations - adverse effects; Plant Preparations - pharmacology; Site-specific Recombination; Suppressor Mutations; Tumor Suppressor Gene; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism; Urethral Neoplasms - chemically induced; Urethral Neoplasms - genetics; Urethral Neoplasms - metabolism; Urethral Neoplasms - pathology; Urothelium - metabolism; Urothelium - pathology; Mutagenesis Mechanisms; Suppressor Mutations; Cellular Senescence; Molecular Cell Biology; Mouse Genetics; Biomarkers; Cancer Biology; Tumor Suppressor Gene; Site-specific Recombination
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M112.443168

Exposure to herbal remedies containing the carcinogen aristolochic acid (AA) has been widespread in some regions of the world. Rare A→T TP53 mutations were recently discovered in AA-associated urothelial cancers. The near absence of these mutations among all other sequenced human tumors suggests that they could be biologically silent. There are no cell banks with established lines derived from human tumors with which to explore the influence of the novel mutants on p53 function and cellular behavior. To investigate their impact, we generated isogenic mutant clones by integrase-mediated cassette exchange at the p53 locus of platform (null) murine embryonic fibroblasts and kidney epithelial cells. Common tumor mutants (R248W, R273C) were compared with the AA-associated mutants N131Y, R249W, and Q104L. Assays of cell proliferation, migration, growth in soft agar, apoptosis, senescence, and gene expression revealed contrasting outcomes on cellular behavior following introduction of N131Y or Q104L. The N131Y mutant demonstrated a phenotype akin to common tumor mutants, whereas Q104L clone behavior resembled that of cells with wild-type p53. Wild-type p53 responses were restored in double-mutant cells harboring N131Y and N239Y, a second-site rescue mutation, suggesting that pharmaceutical reactivation of p53 function in tumors expressing N131Y could have therapeutic benefit. N131Y is likely to contribute directly to tumor phenotype and is a promising candidate biomarker of AA exposure and disease. Rare mutations thus do not necessarily point to sites where amino acid exchanges are phenotypically neutral. Encounter with mutagenic insults targeting cryptic sites can reveal specific signature hotspots. Background: Biological consequences of novel signature mutations in the p53 gene of tumors from patients exposed to Aristolochia medicines are not yet known. Results: N131Y, a prominent Aristolochia-linked mutation, confers cancer-associated behavior to cells. Conclusion: Rare mutations in cancer genes can have profound consequences to protein function. Significance: N131Y is a candidate biomarker of Aristolochia-related disease and target for pharmacological rescue of p53 function.