Emiel Janssen
Stavanger University Hospital,Norway
Title: The Role of MicroRNAs as Predictors of Response to Tamoxifen Treatment in Breast Cancer Patients
Biography
Biography: Emiel Janssen
Abstract
Endocrine therapy, via tamoxifen or aromatase inhibitor, is a key treatment strategy to control and eradicate breast cancer. However, resistance to endocrine therapy leads to breast cancer relapse. The recent extension of adjuvant tamoxifen treatment up to 10 years actualizes the need for monitoring breast cancer development during treatment. MicroRNAs are promising biomarkers that may fill the gap between preclinical knowledge and clinical observations regarding endocrine resistance. MicroRNAs regulate gene expression by posttranscriptional repression or degradation of mRNA, most often leading to gene silencing. MicroRNAs have been identified directly in the primary tumour, but also in the circulation of breast cancer patients. The few available studies investigating microRNA in patients suggest that seven microRNAs (miR-10a, miR-26, miR-30c, miR-126a, miR-210, miR-342 and miR-519a) play a role in tamoxifen resistance. Ingenuity Pathway Analysis (IPA) reveals that these seven microRNAs interact more readily with oestrogen receptor (ER) independent pathways than ER-related signalling pathways. Some of these pathways are targetable (e.g. PIK3A) suggesting that microRNAs as biomarkers of endocrine resistance may have clinical value. Validation of the role of these candidate microRNAs in large prospective studies is warranted. Currently a microRNA profiling study has been performed in ER-pos breast cancer patients with and without recurrences under tamoxifen treatment. Results from the literature and the profiling studies will be compared with each other.