Sequence characterization of baculoviral inhibitor of apoptosis repeat containing 5 (BIRC 5) gene from a case of canine mammary tumour

Abstract

The BIRC 5 (also called survivin), member of the inhibitor of apoptosis protein family is highly over-expressed in human and animal cancers leading to poor prognosis. Still there is limited information about the gene sequence in dogs suffering with canine mammary tumour. Therefore, the present study was undertaken to find out any correlation of BIRC 5 gene over-expression with mutation status of the gene. The CMT tissues were confirmed by histopathological examination and included cases of mixed myoepithelioma, complex adenocarcinoma, mixed mammary capillary cystic adenocarcinoma and invasive solid carcinoma etc. Quantitative Real Time PCR (qRT-PCR) revealed 5.6±0.462-60.0±1.476 fold higher BIRC 5 gene expression levels in CMT tissues as compared to dog normal mammary gland tissues. The coding region of the gene was amplified, cloned and sequenced from a case of complex mammary carcinoma showing approximately 60.0±1.476 fold amplification of BIRC 5 gene. The sequence showed 100% similarity with the mRNA sequences of normal dog BIRC 5 present in NCBI. This indicates that BIRC 5 gene sequence in healthy dogs is similar to dogs suffering from CMT and showing over-expression of the gene. The multiple sequence alignment of the survivin gene with other species like cat, cow, buffalo, sheep, goat and human etc. revealed more than 90% similarity. The phylogenetic analysis demonstrates that gene is highly conserved across species to maintain its functional integrity. The findings revealed that there is no sequence alteration in BIRC 5 gene sequence in the CMT tissue showing more than 60 fold over-expression of the gene.