Breast cancer is the most common malignancy diagnosed in women worldwide with the highest incidence rate for cancer-related death. There are many different subtypes of breast cancer and because of this heterogeneity, finding the most suitable treatment is crucial. This study focuses on the subtype with the worst prognosis, termed Triple Negative Breast Cancer (TNBC). The major characteristics of this subtype are the absence of hormone receptors for estrogen, progesterone and the human epidermal growth factor 2 (HER2). TNBC is known to be more aggressive than other breast cancer subtypes, with more frequent and rapid metastatic spread after initial diagnosis. Metastases are the major issue in cancer progress, and are associated with a significant decrease in survival. For TNBC patients, there is currently no targeted therapy available and little information to develop new approaches to treatment.
Multiple studies provide evidence that microRNAs (miRNAs) are involved in tumour initiation as well as metastasis. In previous studies, we have found 27 differentially expressed miRNAs in TNBC patients with metastases compared to those without metastases.
To understand the functional role of these microRNAs it is important to identify their target genes. This study has analysed gene expression profiles of 31 primary TNBC tumours, 13 matched lymph node metastases, and 23 matched normal breast tissues, by using Affymetrix Gene Chip® Human Gene 2.0 ST Arrays, to identify the microRNA target genes. Results were analysed using GeneSpring GX software. This study has potential to identify important pathways that are regulated by microRNAs and that are involved in cancer progression.