Estrogen Receptor and Signal Transducer and Activator of Transcription 3 Expression in Equine Mammary Tumors.
Authors: Hughes K, Scase T J, Foote A K
Journal: Veterinary pathology
Summary
# Editorial Summary: Estrogen Receptor and STAT3 Expression in Equine Mammary Tumors Equine mammary tumours represent a poorly characterised malignancy with limited molecular data to guide clinical management; Hughes and colleagues addressed this gap by conducting immunohistochemical analysis of seven cases to determine expression patterns of oestrogen receptor α (ER-α) and signal transducer and activator of transcription 3 (STAT3). The tumours demonstrated consistently aggressive features including infiltrative growth, intermediate to high mitotic rates, and extensive necrosis, alongside variable expression of vimentin and cytokeratin 14 and strong E-cadherin staining—a profile consistent with malignant epithelial origin. Notably, a subset exhibited robust nuclear ER-α staining, whilst STAT3 nuclear expression was identified in three of seven cases, with an inverse relationship observed between STAT3 activation and high cytokeratin 14 expression. These findings suggest that some equine mammary tumours share molecular characteristics with their feline and canine counterparts, potentially opening pathways for hormone-responsive therapeutic strategies and prognostic stratification based on ER-α and STAT3 status, though larger sample sizes are needed to establish clinical relevance and inform evidence-based treatment protocols in affected animals.
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Practical Takeaways
- •Equine mammary tumors are malignant lesions with aggressive histologic features; any identified mammary mass warrants prompt surgical removal and histopathologic evaluation
- •A subset of equine mammary tumors may be hormone-responsive based on estrogen receptor expression; future targeted endocrine therapies used in dogs and cats may have potential applications in equine cases
- •Molecular profiling (ER-α and STAT3 status) may help stratify prognosis and guide treatment selection in equine mammary tumors, though larger studies are needed
Key Findings
- •7 equine mammary tumors exhibited infiltrative growth, intermediate to high mitotic rates, and focally extensive necrosis consistent with malignant phenotype
- •Subgroup of tumors showed strong nuclear estrogen receptor α expression, suggesting molecular similarity to feline and canine mammary tumors
- •3 of 7 tumors exhibited nuclear STAT3 expression indicating transcriptional activity, while carcinomas with moderate to intense cytokeratin 14 staining showed rare to absent STAT3 expression