Prevalence of p53 dysregulations in feline oral squamous cell carcinoma and non-neoplastic oral mucosa

Abstract

Squamous cell carcinoma is the most common malignant oral tumor in cats. The late presentation is one of the factors contributing to the detrimental prognosis of this disease. The immunohistochemical expression of the p53 tumor suppressor protein has been reported in 24% to 65% of feline oral squamous cell carcinomas, but no study has systematically evaluated in this tumor the presence of p53 encoding gene ( TP53 ) mutations. The aim of this retrospective study was to determine whether p53 immunohistochemistry accurately reflects the mutational status of the TP53 gene in feline oral squamous cell carcinoma. Additionally, the prevalence of p53 dysregulation in feline oral squamous cell carcinoma was compared with that of feline non-neoplastic oral mucosa, in order to investigate the relevance of these dysregulations in cancer development. The association between p53 dysregulations and exposure to environmental tobacco smoke and tumor characteristics was further assessed. Twenty-six incisional biopsies of oral squamous cell carcinomas and 10 cases each of lingual eosinophilic granuloma, chronic gingivostomatitis and normal oral mucosa were included in the study. Eighteen squamous cell carcinomas (69%) expressed p53 and 18 had mutations in exons 5–8 of TP53 . The agreement between immunohistochemistry and mutation analysis was 77%. None of non-neoplastic oral mucosa samples had a positive immunohistochemical staining, while one case each of eosinophilic granuloma and chronic gingivostomatitis harbored TP53 mutations. Unlike previously hypothesized, p53 dysregulations were not associated with exposure to environmental tobacco smoke. These results suggest an important role of p53 in feline oral tumorigenesis. Additionally, the immunohistochemical detection of p53 expression appears to reflect the presence of TP53 mutations in the majority of cases. It remains to be determined if the screening for p53 dysregulations, alone or in association with other markers, can eventually contribute to the early detection of this devastating disease.

Analysis of DNA methylation and TP53 mutational status for differentiating feline oral squamous cell carcinoma from non‐neoplastic mucosa: A preliminary study

“…As in a previous study, 6 *Is used in the standard mutation nomenclature to indicate a translation stop codon; it is part of the nomenclature of the mutation so it does not need to be explained in this specific case.…”

“…TP53 mutations analysis of exons 5‐8 was performed as previously described 6 . Cases were classified as mutated when presenting one or more alterations in the nucleotide sequence of the amplified exons of feline TP53 , resulting in amino acid changes with negative impact on the protein function according to PolyPhen‐2 42 and showing a variant allele frequency >10%.…”

“…Recently, a significantly higher prevalence of TP53 gene mutations was observed in FOSCC compared with normal oral mucosa and inflammatory lesions; this provides another similarity between feline and human disease, and suggests the diagnostic utility of p53 for the detection of oral cancer in cats 6 …”

“…4,5 Recently, a significantly higher prevalence of TP53 gene mutations was observed in FOSCC compared with normal oral mucosa and inflammatory lesions; this provides another similarity between feline and human disease, and suggests the diagnostic utility of p53 for the detection of oral cancer in cats. 6 Over the last two decades, epigenetic alterations have been receiving increasing attention as promoters of tumour initiation and progression, in addition to and even more frequently than structural inactivation of genes by mutations and deletions. [7][8][9] DNA methylation is an epigenetic mechanism that regulates protein functions, gene expression and RNA processing without affecting DNA sequences.…”

An Evolutionary Cancer Epigenetic Approach Revealed DNA Hypermethylation of Ultra-Conserved Non-Coding Elements in Squamous Cell Carcinoma of Different Mammalian Species

“…Quantitative DNA methylation analysis was performed by next-generation sequencing for the following genes: uc.160, uc.283, uc.283 promoter, uc.416, uc.339, uc.270, uc.299, and uc.328. Locus-specific amplicon libraries were generated with tagged primers in two steps: a first PCR amplification for target enrichment, and a second shorter amplification session (eight cycles) to allow the barcoding of the template-specific amplicons obtained from the first amplification step using the Nextera™ Index Kit (Illumina, San Diego, CA, USA) [ 22 , 23 , 24 , 25 , 26 ]. Sequencing was conducted on MiSeq sequencer (Illumina, San Diego, CA, USA), according to the manufacturer’s protocol.…”