Validation of expression of HORMAD1 protein, a cancer/testis antigen, in triple-negative breast cancers with high genomic instability

Research output: Chapter in Book/Report/Conference proceedingMeeting abstract


Background Triple negative breast cancer (TNBC) is a heterogeneous disease with limited targeted therapy with some lesions characterized by high levels of genomic instability (GI). Previously we have shown that the expression of HORMAD1, a gene hardly expressed in somatic tissue, was increased at the mRNA level in TNBC with high levels of GI. HORMAD1 is normally expressed in the gonads. However, little is known about its expression at the protein level outside this context, partly due to the limited characterisation of available antibodies. Given its association to a TNBC subgroup, we aimed to characterize the expression of HORMAD1 protein. Method To optimise and validate antibody, western blot analysis and immunohistochemistry with or without shRNA knockdown or overexpression of HORMAD1 were carried out across a panel of breast cancer cell lines (BCCLs) selected for their HORMAD1 expression-levels at the mRNA level. Subcellular fractionation was also performed to assess the cellular localisation of HORMAD1. Tissue microarray analyses (TMA) encompassing 222 primary breast carcinomas were used to determine immunohistochemically HORMAD1 prevalence in malignant breast tissues. Results High HORMAD1 expressing BCCLs (HCC1143, HCC70 and HCC38) showed predominant nuclear staining that was absent in low HORMAD1 expressing BCCLs (BT20, SUM159), Overall, a good concordance between HORMAD1 protein and transcriptional levels were observed. TMA analysis showed 12% of cores were positive for HORMAD1 nuclear staining (28/222) increasing to 19% (22/111) when TNBC tumours only were considered. Interestingly, HORMAD1 positivity was enriched in bigger tumours T2 & T3; p-value <0.03. Furthermore, of the HORMAD1 positive TNBC tumours 81% (18/22) also had a high GI score. Conclusion Antibody validation and TMA analysis confirmed the presence of HORMAD1 protein at high levels in a subset of TNBC tumours where its expression is associated with high levels of GI and may represent a potential novel biomarker that characterizes this group.
Original languageEnglish
Title of host publicationNCRI conference 2012
Publication statusPublished - 2012


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