Pathological features and molecular phenotype of mmtv like‐positive feline mammary carcinomas

In the last few years MMTV‐like nucleotide sequences were detected in some feline and canine mammary tumours. Due to the confirmed role of cats in the epidemiology of the MMTV‐like virus, the aim of this study was to investigate the main pathological features of positive feline mammary carcinomas (FMCs). Twenty‐four FMCs were collected at the University of Bologna, submitted to laser microdissection and analysed by nested fluorescence‐PCR using primer sets specific for MMTV env sequence. For immunohistochemistry, an antibody against MMTV protein 14 (p14) was used. MMTV‐like sequences were detected in three out of 24 FMCs (12.5%), one tubular carcinoma, one tubulopapillary carcinoma and one ductal carcinoma. All PCR‐positive tumours were also positive for p14. Multiple nucleotide alignment has shown similarity to MMTV ranging from 98% to 100%. All the 102 examined FMCs were submitted to immunohistochemistry for molecular pheno-typing. Of the nine MMTV‐like positive FMCs, six were basal‐like and three luminal‐like. Our results demonstrate MMTV‐like sequences and protein in FMCs of different geographic areas. Molecular phenotyping could contribute to understand the possible role of MMTV‐like virus in FMC tumor biology.