Phillips Jeffrey C, Lembcke Luis M, Noltenius Christina E, Newman Shelley J, Blackford James T, Grosenbaugh Deborah A, Leard A Timothy
Veterinary Teaching Hospital, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, 37996, USA.
Am J Vet Res. 2012 Feb;73(2):272-8. doi: 10.2460/ajvr.73.2.272.
To determine the tissue-restricted expression pattern of tyrosinase mRNA in canine and equine melanocytic tumors and relative tyrosinase and major histocompatibility complex (MHC) I mRNA expression in variants of melanocytic tumors.
39 canine and 8 equine tumor samples and 10 canine and 6 equine normal tissue samples.
RNA was isolated from formalin-fixed, paraffin-embedded tissues. Real-time PCR assays were designed to amplify canine and equine tyrosinase, S18 ribosomal RNA, and major histocompatibility complex I transcripts. Relative expression was determined by use of S18 as a reference and comparison with pigmented and nonpigmented normal tissues.
High tyrosinase expression was found in all melanocytic tumors, compared with normal tissues, and expression had no correlation with presence or absence of tumor pigmentation. No significant difference in tyrosinase expression was found among histologic variants of melanocytic tumors. No correlation was found between MHC I and tyrosinase expression or tissue histologic classification.
In the present study, the methods used were highly sensitive and specific for detection of tyrosinase expression in equine and canine tumors, and overexpression of this transcript in melanomas was detected. This suggested that a DNA vaccine developed for use in dogs with melanoma that targets tyrosinase may be considered for use in other affected species, such as horses.
