Nuclear Myosin VI - a Therapeutic Target in Breast Cancer

Overview

Gene expression, the transfer of the genetic code into cellular proteins is one of the most fundamental processes in living cells. This process is orchestrated by protein-based molecular machines, called RNA polymerases that read the DNA sequence to generate messenger RNA (mRNA), which is translated by the cellular machinery to make proteins. Our cells have evolved elaborate regulation mechanisms to control these molecular machines and a breakdown in this regulation leads to diseases such as cancer. Recently, molecules called myosins have been discovered in the genetic storage compartment of the cell (the nucleus) where they interact with RNA polymerases to regulate protein production. This is interesting because myosins are usually found outside the nucleus transporting cellular cargo or generating muscle contraction. In breast cancer cells, myosin is abundant and interacts with the oestrogen receptor. The majority of breast cancer in the UK is oestrogen receptor positive and activation of this receptor is an important factor controlling the growth of cancer cells. Oestrogen receptor activation appears to be dependent upon myosin and this research project will investigate how myosins are targeted to specific genes and how they are themselves regulated. This will greatly enhance our understanding of the role of nuclear myosins in oestrogen receptor positive breast cancer and may identify a novel therapeutic target for future drug development.

Purpose and Design The primary aim of this project is to understand the significance of the newly discovered interaction between myosin VI (MVI) and the oestrogen receptor in breast cancer cells. The study will investigate the types of genes that MVI regulates and whether the sites of MVI - oestrogen receptor interactions (nucleus or cytoplasm) are important for the expression of oestrogen receptor targets. In breast cancer cells, oestrogen receptors can mutate to become permanently activated, leading to unrestrained tumour growth. Investigating the role of MVI in this metabolic scenario may reveal a potential therapeutic window for hormone refractory oestrogen receptor positive breast cancer. In order to answer these questions, the methodology will use combination of experiments on established cell lines and patient samples. The research proposal is a collaborative effort between Dr Chris Toseland (whose group has identified the link between MVI and the oestrogen receptor) at the University of Kent and the Breast Surgery, Pathology and Research and Development departments at Maidstone and Tunbridge Wells NHS Trust. Recruitment Potential patients for recruitment will be identified at the weekly multi-disciplinary meeting following a diagnosis of primary breast cancer and a decision to proceed with surgery as the first treatment. The actual explanation of the study will take place during the first treatment planning consultation with the treating breast surgeon. The patient will be given written information about the study as well as a contact number of a research nurse/ breast care nurse specialist for them to call if they wish to be included in the study. A second clinic appointment will be made with the co-investigator Miss Karina Cox to re-discuss the trial and obtain written consent. The consultant surgeon is familiar with the process of consent and will determine whether the patient has capacity to give consent for the study. We will exclude all patients with a metabolic disorder, significant co-morbidities and locally advanced or metastatic disease as well as those with a previous history of cancer treatment as the results of the study may be affected by their underlying disorder, previous treatment or current medication. Confidentiality The study will be conducted within the "Caldicott Principles'. Patients enrolled in the study will be given a unique identification number which will used on samples sent to The University of Kent for experiments. The clinical co-investigator will maintain a secure database of patient identifiable information including demographic and clinico-pathological tumour data. Conflict of Interest There are no conflicts of interest with this study. Any publications relating to this research will be summarised and distributed to participating patients. Tissue samples will not be stored indefinitely. All the tissue from the fresh frozen specimens will be used for the experiments. The paraffin slides, once analysed, will be returned from the University of Kent to Maidstone and Tunbridge Wells Pathology Department.