Vimentin and laminin expression is associated with basal-like phenotype in both sporadic and BRCA1-associated breast carcinomas

Abstract

Purpose: Vimentin is expressed by mammary myoepithelial cells while laminin is produced by them. Given that myoepithelial markers are frequently expressed in breast carcinomas with basal-like-phenotype, the aim of this study was to determine whether basal-like-phenotype and vimentin and/or laminin were related in both sporadic and familial (BRCA1 or BRCA2-mutated) tumors.

Material and Methods: 230 nonfamilial and 28 hereditary node-negative invasive breast carcinomas were immunohistochemically analyzed for estrogen receptor (ER), progesterone receptor (PR), Cytokeratin 5/6 (CK5/6), Epidermal Growth Factor Receptor (EGFR), ki67, p53, vimentin and laminin, using tissue microarrays. Tumours were considered to have basal-like-phenotype if they were ER negative, HER2 negative, but positive for CK5/6 and/or EGFR.

Results: In sporadic tumors, vimentin expression was found in 77.8% cases with basal-like-phenotype, whereas in only 15.5% of non-basal cases (p<0.001). Likewise, in familial cases, vimentin was expressed in 83.3% basal-like cancers but in 16.7% of non-basal tumors (p<0.001). Moreover, vimentin expression was more frequent in BRCA1 than BRCA2 mutation carriers. Additionally, vimentin expressing tumors were associated with poor prognosis (p=0.012) among patients not receiving adjuvant chemotherapy and showed a trend for local recurrence or visceral but not bone metastasis (p=0.035). Laminin expression was also related to a basal-like phenotype in both sporadic and familial cases (p<0.001 and p=0.007, respectively), but neither with prognosis nor recurrence pattern in sporadic cancers.

Conclusions: Vimentin and laminin expression is associated with a basal-like- phenotype in breast cancer. In addition, this study reports for the first time that in the hereditary setting, expression of vimentin and laminin is characteristic of BRCA1-associated tumors. Since vimentin and laminin staining is widely used by pathologist for diagnostic purposes, thus demonstrating the robustness of their specific antibodies, we propose to apply the inmunohistochemical evaluation of these two molecules also for the identification of basal-like breast tumors in both sporadic and familial cases.