Introduction We investigated clinical and pathologic features of breast cancers (BC) in an unselected series of patients diagnosed in a tertiary care hospital serving a diverse population. We focused on triple-negative (Tneg) tumours (oestrogen receptor (ER), progesterone receptor (PR) and HER2 negative), which are associated with poor prognosis.

Invasive lobular carcinoma (ILC) of the breast, characterized by loss of E-cadherin expression, accounts for 5-15% of invasive breast cancers and it is believed to arise via a linear histological progression. Genomic studies have identified a clonal relationship between ILC and concurrent lobular carcinoma in situ (LCIS) lesions, suggesting that LCIS may be a precursor lesion. It has been shown that an LCIS diagnosis confers a 15-20% risk of progression to ILC over a lifetime. Currently no molecular test or markers can identify LCIS lesions likely to progress to ILC. Since microRNA (miRNA) expression changes have been detected in a number of other cancer types, we explored whether their dysregulation might be detected during progression from LCIS to ILC. Using the Illumina miRNA profiling platform, designed for simultaneous analysis of 470 mature miRNAs, we analysed the profiles of archived normal breast epithelium, LCIS lesions found alone, LCIS lesions concurrent with ILC, and the concurrent ILCs as a model of linear histological progression towards ILC. We identified two sets of differentially expressed miRNAs, the first set highly expressed in normal epithelium, including hsa-miR-224, -139, -10b, -450, 140, and -365, and the second set up-regulated during lobular neoplasia progression, including hsa-miR-375, -203, -425-5p, -183, -565, and -182. Using quantitative RT-PCR, we validated a trend of increasing expression for hsa-miR-375, hsa-miR-182, and hsa-miR-183 correlating with ILC progression. As we detected increased expression of hsa-miR-375 in LCIS lesions synchronous with ILC, we sought to determine whether hsa-miR-375 might induce phenotypes reminiscent of lobular neoplasia by expressing it in the MCF-10A 3D culture model of mammary acinar morphogenesis. Increased expression of hsa-miR-375 resulted in loss of cellular organization and acquisition of a hyperplastic phenotype. These data suggest that dysregulated miRNA expression contributes to lobular neoplastic progression.

Class III β-tubulin (βIII-tubulin) has been associated with tumor response to taxane-based therapies in breast cancer. However its role in the neoadjuvant setting has not been explored. We evaluated βIII-tubulin expression by immunohistochemistry in 44 patients, and found high expression associated with good pathologic response in estrogen receptor–negative (ER−) breast cancers. Our results give strong reason to consider βIII-tubulin as a predictive biomarker for neoadjuvant chemotherapy response. Background Expression of class III β–tubulin (βIII-tubulin) correlates with tumor progression and resistance to taxane-based therapies for several human malignancies including breast cancer. However its predictive value in a neoadjuvant setting in breast cancer remains unexplored. The objective of this explorative study was to determine whether βIII-tubulin expression in breast cancer correlated with pathologic characteristics and whether its expression was predictive of response to neoadjuvant chemotherapy. Patients and Methods We determined βIII-tubulin expression in 85 breast cancers, including 41 localized breast cancers treated with primary surgery and 44 treated with neoadjuvant chemotherapy before surgery. βIII-tubulin expression was evaluated by immunohistochemical methods and was correlated with pathologic characteristics and response to neoadjuvant chemotherapy using residual cancer burden (RCB) score. Results High βIII-tubulin expression was significantly associated with poorly differentiated high-grade breast cancers (P = .003) but not with tumor size, estrogen receptor (ER) status, or human epidermal growth factor receptor 2 (HER2)/neu overexpression. In ER− tumors treated with neoadjuvant chemotherapy, high βIII-tubulin expression was associated with a significantly greater likelihood of achieving a good pathologic response to chemotherapy as reflected by lower RCB scores (P = .021). Conclusion This study reveals differential βIII-tubulin expression in breast cancers of different histologic grades, hormone receptors, and HER2/neu status. It also suggests a potential role for βIII-tubulin as a predictive biomarker for response in neoadjuvant chemotherapy for ER− breast cancer, which has not been previously reported. These data provide a strong rationale for considering βIII-tubulin status and further validation of this marker in a large study.