Mutations of p53 Gene in Canine Sweat Gland Carcinomas Probably Associated with UV Radiation

Abstract

Introduction: Apocrine sweat gland carcinomas (ASGCs) are rare malignant skin tumours in dogs and humans. The literature published so far focuses mostly on the clinico-epidemiological aspect of these tumours, but little is known about their pathogenesis. In this study we aimed to determine whether the p53 gene is involved in the carcinogenesis of the apocrine sweat gland in dogs and whether ultraviolet radiation (UV) is related to it.

Material and methods: Forty canine ASGCs were submitted to laser capture microdissection to isolate neoplastic cells, from which DNA was subsequently extracted. PCR amplification and sequencing of p53 exons 2-8 was then performed, followed by computer analysis of the obtained sequences.

Results: Sixteen mutations within the p53 gene were found in 13 tumours. The mutations involved C → T, T → C, G → A, and CC → TT transitions, C → G transversion and adenine deletion, which are gene alteration types known to be related to UV radiation in the process of skin carcinogenesis in humans. Six of the thirteen tumour cases displayed the C → T transitions in the same location in exon 4 and three of the thirteen cases displayed T → C in the same location in exon 5.

Conclusion: The results of the present study indicate both the participation of the p53 gene and the influence of UV radiation in the formation of ASGCs in dogs.

Keywords: UVR; apocrine sweat gland carcinoma; dog; p53 gene, mutations.

Fig. 1

Example images of the laser capture microdissection of tumour cells acquired using Arcturus XT operating software (10× objective). A – Haematoxylin and eosin stained section, covered with xylene for visualisation, showing cystic/papillary type apocrine sweat gland carcinoma before microdissection, with the area containing tumour cells marked with a red line. B – The same section with marked tumour cells and laser infrared spots (IR spots). C – The same section after xylene evaporation and the microdissection of the marked cells. D – Tumour cells transferred to the macro cap after laser capture microdissection

Fig. 2

Alignment of the amino acid sequence of exon 4 of the p53 protein of the canine control (K1) sample and tested samples of apocrine sweat gland carcinomas with canine (U62133, AB020761) and human (K03199) amino acid reference sequences of the p53 protein

Fig. 3

Alignment of the amino acid sequence of exon 5 of the p53 protein of the canine control (K1) sample and tested samples of apocrine sweat gland carcinomas with canine (U62133, AB020761) and human (K03199) amino acid references sequence of the p53 protein

Fig. 4

Alignment of the amino acid sequence of exon 6 of the p53 protein of the canine control (K1) sample and tested samples of apocrine sweat gland carcinoma with canine (U62133, AB020761) and human (K03199) amino acid reference sequences of the p53 protein

Fig. 5

Alignment of the amino acid sequence of exon 8 of p53 of the canine control (K1) sample and tested samples of apocrine sweat gland carcinomas with canine (U62133, AB020761) and human (K03199) amino acid reference sequences of the p53 protein