Hspb1 and Tp53 Mutation and Expression Analysis in Cat Mammary Tumors.

BACKGROUND: Molecular marker based cancer diagnosis gaining more attention in the current genomics era. So, Hspb1 and Tp53 gene characterization and their mRNA expression might be helpful in diagnosis and prognosis of cat mammary adenocarcinoma. It will also add information in comparative cancer genetics and genomics.

OBJECTIVES: Eight tumors of Siamese cats were analyzed to ascertain germ-line and tissue-specific somatic DNA variations of Hspb1 and Tp53 genes along with the ectopic differential expression in tumorous and normal tissues were also analyzed.

MATERIALS AND METHODS: Tumorous tissues and peripheral blood from mammary adenocarcinoma affected Siamese cats were collected from the Pet center-UVAS. DNA and RNA were extracted from these tissues to analyze the Hspb1 and Tp53 DNA variants and ectopic expression of their mRNA within cancerous and normal tissues.

RESULTS: Exon 1 and 3 revealed as hotspots in Hspb1 gene. The 5´UTR region of the exon1 bear six mutation including 3 transitions, 2 transversion and one heterozygous synonymous transversion in two samples at locus c.34C>C/A. Exon 3 has 1 transversion at c.773A>A/T, 3´UTR of this exon harbor two point mutations at 1868A>T and 2193C>T loci. Intron 2 has two alterations at 1490C>C/T and GTCT4del at 1514. Overall up-regulation of Hspb1 gene was observed. While exons 3, 4 and 7 of Tp53 harbor a single variationat c.105A>A/G, c.465T>T/C and c.859G>T respectively. The locus c.1050G>G/A in exon 9 is a heterozygous (G/A) in 3 samples and homozygous (G) in 2 other tumours. Introns 3, 5, 7 and 9 harbor 3, 4, 2 and 7 altered loci respectively. Sixty percent of cancers showed up-regulated trend of Tp53 gene.

CONCLUSIONS: Tumor specific mutations and ectopic expression of Hspb1 and Tp53 genes might be helpful in the diagnosis of the mammary lesions and endorse their involvement in cat mammary neoplasm.