TRPS1 As an Immunohistochemical Biomarker in Breast Carcinoma: Clinicopathological Correlates and Molecular Subtype-Specific Expression

Abstract

Breast carcinoma is a biologically heterogeneous malignancy showing diverse histopathological and immunophenotypic features. Immunohistochemical biomarkers complement histopathological classification of tumour. In recent times, TRPS1 (a transcriptional repressor of mammary epithelial differentiation) has been highlighted as a candidate associated to the breast lineage marker. Yet, its expression across clinicopathological parameters and surrogate molecular subtypes in different populations is still incompletely characterised. The aim of this study is to evaluate TRPS1 immunohistochemical expression in cancerous and noncancerous tissues using invasive breast carcinoma samples, as well as correlating its expression with various clinicopathological parameters and surrogate molecular subtypes among an Iraqi population. The study was performed on 50 female patients diagnosed with primary invasive carcinoma of breast. Archival formalin-fixed paraffin-embedded formalin-fixed paraffin-embedded tissue blocks were retrieved from pathology collections and stained with a rabbit monoclonal anti-TRPS1 antibody. Nuclear staining intensity and proportion of the positive tumour cells was evaluated via semi-quantitative immunoreactivity scoring system. TRPS1 expression was identified in 39/50 (78.0%) of cases, with moderate to strong nuclear staining in most instances. Expression showed some consistency between histological subtypes and tumour grades. TRPS1 expression was statistically significantly associated with surrogate molecular subtype classification (p = 0.046) and tended to be up-regulated in tumours classified as luminal-like compared with HER2-enriched and triple-negative groups. Associations between TRPS1 expression and age, histological type, tumour grade, or TNM components were statistically not significant.TRPS1 is commonly expressed in invasive breast carcinoma and has a heterogeneous distribution among surrogate molecular subtypes, with the highest expression level seen in hormone receptor–positive tumours within this cohort. Nonetheless, its expression is not strongly related to grade, stage or any other major clinicopathological parameters. These results reinforce the concept that TRPS1 should be regarded as a breast-lineage–specific immunohistochemical marker rather than a prognostic determinant. It is best viewed as an adjunct to immunohistochemical panels in diagnostic settings rather than a stand-alone diagnostic test.

Keywords:

Breast carcinoma, Immunohistochemistry, TRPS1, immunoreactivity

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