Breast cancer is the leading cause of cancer related death in women, with metastasis the principle cause of mortality. New non-invasive prognostic markers are needed for the early detection of metastasis, facilitating treatment decision optimisation. MicroRNA (miRNA) are small, non-coding RNAs regulating gene expression and involved in many cellular processes, including metastasis. As biomarkers, circulating miRNAs (in blood) hold great promise for informing diagnosis or monitoring treatment responses. Plasma extracted RNA from age matched local Luminal A (n = 4) or metastatic disease (n = 4) were profiled using Next Generation Sequencing. Selected differentially expressed miRNA were validated on a whole blood extracted miRNA cohort [distant metastatic disease (n = 22), local disease (n = 31), healthy controls (n = 21)]. Area Under the Curve (AUC) in Receiver Operating Characteristic (ROC) analyses was performed. Of 4 miRNA targets tested (miR-181a, miR-329, miR-331, miR-195), mir-331 was significantly over-expressed in patients with metastatic disease, compared to patients with local disease (p < 0.001) or healthy controls (p < 0.001). miR-195 was significantly under-expressed in patients with metastatic disease, compared to patients with local disease (p < 0.001) or healthy controls (p = 0.043). In combination, miR-331 and miR-195 produced an AUC of 0.902, distinguishing metastatic from local breast cancer. We identified and validated two circulating miRNAs differentiating local Luminal A breast cancers from metastatic breast cancers. Further investigation will reveal the molecular role of these miRNAs in metastasis, and determine if they are subtype specific. This work demonstrates the ability of circulating miRNA to identify metastatic disease, and potentially inform diagnosis or treatment effectiveness.

Background: The debate continues as to whether younger women who present with breast cancer have a more aggressive form of disease and a worse prognosis. The objectives of this study were to determine the incidence of breast cancer in women under 40 years old and to analyse the clinicopathological characteristics and outcome compared to an older patient cohort. Methods: Data was acquired from a review of charts and the prospectively reviewed GUH Department of Surgery database. Included in the study were 276 women diagnosed with breast cancer under the age of forty and 2869 women over forty. For survival analysis each women less than 40 was matched with two women over forty for both disease stage and grade. Results: The proportion of women diagnosed with breast cancer under the age of forty in our cohort was 8.8%. In comparison to their older counterparts, those under forty had a higher tumour grade (p = 0.044) and stage (p = 0.046), a lower incidence of lobular tumours (p < 0.001), higher estrogen receptor negativity (p < 0.001) and higher HER2 over-expression (p = 0.002); there was no statistical difference as regards tumour size (p = 0.477). There was no significant difference in overall survival (OS) for both groups; and factors like tumour size (p = 0.026), invasion (p = 0.026) and histological type (p = 0.027), PR (p = 0.031) and HER2 (p = 0.002) status and treatment received were independent predictors of OS Conclusion: Breast cancer in younger women has distinct histopathological characteristics; however, this does not result in a reduced survival in this population.

MicroRNAs (miRNAs) are short non-coding RNA molecules that play a critical role in mRNA cleavage and translational repression, and are known to be altered in many diseases including breast cancer. MicroRNA-10a (miR-10a) has been shown to be deregulated in various cancer types. The aim of this study was to investigate miR-10a expression in breast cancer and to further delineate the role of retinoids and thyroxine in regulation of miR-10a. Following informed patient consent and ethical approval, tissue samples were obtained during surgery. miR-10a was quantified in malignant (n = 103), normal (n = 30) and fibroadenoma (n = 35) tissues by RQ-PCR. Gene expression of Retinoic Acid Receptor beta (RARβ) and Thyroid Hormone receptor alpha (THRα) was also quantified in the same patient samples (n = 168). The in vitro effects of all-trans Retinoic acid (ATRA) and L-Thyroxine (T4) both individually and in combination, on miR-10a expression was investigated in breast cancer cell lines, T47D and SK-BR-3. The level of miR-10a expression was significantly decreased in tissues harvested from breast cancer patients (Mean (SEM) 2.1(0.07)) Log10 Relative Quantity (RQ)) compared to both normal (3.0(0.16) Log10 RQ, p < 0.001) and benign tissues (2.6(0.17) Log10 RQ, p < 0.05). The levels of both RARβ and THRα gene expression were also found to be decreased in breast cancer patients compared to controls (p < 0.001). A significant positive correlation was determined between miR-10a and RARβ (r = 0.31, p < 0.001) and also with THRα (r = 0.32, p < 0.001). In vitro stimulation assays revealed miR-10a expression was increased in both T47D and SK-BR-3 cells following addition of ATRA (2 fold (0.7)). While T4 alone did not stimulate miR-10a expression, the combination of T4 and ATRA was found to have a positive synergistic effect. The data presented supports a potential tumour suppressor role for miR-10a in breast cancer, and highlights retinoic acid as a positive regulator of the microRNA.

Recent studies have shown that breast cancer subtype can change from the primary tumour to the recurrence. Discordance between primary and recurrent breast cancer has implications for further treatment and ultimately prognosis. The aim of the study was to determine the rate of change between primary and recurrence of breast cancer and to assess the impact of these changes on survival and potential treatment options. Patient demographics were collected on those who underwent surgery for breast cancer between 2001 and 2014 and had a recurrence with biopsy results and pathology scoring of both the primary and recurrence. One hundred thirty two consecutive patients were included. There were 31 (23.5%) changes in subtype. Discordance occurred most frequently in luminal A breast cancer (n = 20), followed by triple negative (n = 4), luminal B (n = 3) and HER2 (n = 3). Patients who changed from luminal A to triple negative (n = 18) had a significantly worse post-recurrence survival (p < 0.05) with overall survival approaching significance (p = 0.064) compared to concordant luminal A cases (n = 46). Overall receptor discordance rates were: estrogen receptor 20.4% (n = 27), progesterone receptor 37.7% (n = 50) and HER2 3% (n = 4). Loss of estrogen receptor and progesterone receptor was more common than gain (21 vs. 6 (p = 0.04) and 44 vs. 6 (p = 0.01) respectively). Nine patients (6.8%) gained receptor status potentially impacting treatment options. Discordance in subtype and receptor status occurs between primary and recurrent breast cancer, ultimately affecting survival and potentially impacting treatment options.

Argonaute-2 (Ago2) is an essential component of microRNA biogenesis implicated in tumourigenesis. However Ago2 expression and localisation in breast cancer remains undetermined. The aim was to define Ago2 expression (mRNA and protein) and localisation in breast cancer, and investigate associations with clinicopathological details. Ago2 protein was stained in breast cancer cell lines and tissue microarrays (TMAs), with intensity and localization assessed. Staining intensity was correlated with clinicopathological details. Using independent databases, Ago2 mRNA expression and gene alterations in breast cancer were investigated. In the breast cancer TMAs, 4 distinct staining intensities were observed (Negative, Weak, Moderate, Strong), with 64.2% of samples stained weak or negatively for Ago2 protein. An association was found between strong Ago2 staining and, the Her2 positive or basal subtypes, and between Ago2 intensity and receptor status (Estrogen or Progesterone). In tumours Ago2 mRNA expression correlated with reduced relapse free survival. Conversely, Ago2 mRNA was expressed significantly lower in SK-BR-3 (HER2 positive) and BT-20 (Basal/Triple negative) cell lines. Interestingly, high levels of Ago2 gene amplification (10–27%) were observed in breast cancer across multiple patient datasets. Importantly, knowledge of Ago2 expression improves predictions of breast cancer subtype by 20%, ER status by 15.7% and PR status by 17.5%. Quantification of Ago2 improves the stratification of breast cancer and suggests a differential role for Ago2 in breast cancer subtypes, based on levels and cellular localisation. Further investigation of the mechanisms affecting Ago2 dysregulation will reveal insights into the molecular differences underpinning breast cancer subtypes.