The identification of selenium induced changes in normal and lymphoma cells.
Lead Research Organisation:
Queen Mary University of London
Department Name: Barts Cancer Institute
Abstract
Selenium is a trace element vital to human health. In cancer, its effects are concentration dependent. Low concentrations play a role in cancer prevention, high concentrations induce cell death, while intermediate concentrations enhance the effect of chemotherapy while protecting normal tissue from toxicity. This study aims to determine mechanisms underlying these differential effects of intermediate selenium concentrations between tumour cells and normal cells.
The effects of selenium in lymphomas will be investigated in established cell lines and in tumour samples collected from lymphoma patients entered into a clinical trial of methylselenocysteine given with chemotherapy. Normal cells will be isolated from blood and skin collected from healthy individuals. Changes in stress response and signalling pathways important in cancer, and implicated in selenium activity, will be studied. In addition to understanding how selenium induces these effects we also aim to identify proteins that can be measured in blood cells that could be used to indicate the effectiveness of selenium in patients.
The potential implications of this research are that adding selenium to chemotherapy may provide a simple way of improving treatment outcome in lymphoma patients. This research will be conducted by a Clinical Research Fellow in the Centre for Medical Oncology.
The effects of selenium in lymphomas will be investigated in established cell lines and in tumour samples collected from lymphoma patients entered into a clinical trial of methylselenocysteine given with chemotherapy. Normal cells will be isolated from blood and skin collected from healthy individuals. Changes in stress response and signalling pathways important in cancer, and implicated in selenium activity, will be studied. In addition to understanding how selenium induces these effects we also aim to identify proteins that can be measured in blood cells that could be used to indicate the effectiveness of selenium in patients.
The potential implications of this research are that adding selenium to chemotherapy may provide a simple way of improving treatment outcome in lymphoma patients. This research will be conducted by a Clinical Research Fellow in the Centre for Medical Oncology.
Technical Summary
Selenium is an essential trace element that is fundamentally important to human health. Specifically in cancer cells the effects of selenium are concentration-dependent. At low concentration selenium can prevent cancer development, at intermediate concentration it can modulate the therapeutic efficacy of chemotherapeutic agents and reduce toxicity, while at higher concentration it is cytotoxic. Possible mechanisms mediating the chemo-modulatory effects of selenium include altered cellular stress responses and changes in key cell signalling pathways involving PI3K/AKT and NF-?B. This study will focus on these chemo-modulatory mechanisms and will run in conjunction with a phase I/II clinical trial of methylselenocysteine in patients with Diffuse Large B-Cell Lymphoma.
The aims of the project are to; 1) identify key mechanisms by which selenium sensitises lymphoma cells to chemotherapy, 2) study selenium effects in normal cells and investigate how selenium protects against chemotherapy induced toxicity, 3) identify potential biomarkers that might be used for the clinical evaluation of selenium.
These studies will involve the use of lymphoma cell lines, primary lymphoma samples and normal tissue, including peripheral blood mononuclear cells (PBMCs), primary human keratinocytes and a normal lymphoid cell line (NC-NC). The effects of methylseleninic acid (MSA), alone and with cytotoxic drugs, will be studied using cell proliferation/viability assays, flow cytometry to investigate cell cycle and apoptotic effects and western blot analyses to determine effects on stress response proteins and signalling pathways. MSA induced changes in NF-?B activity will be measured in normal cells, in stored PBMCs from lymphoma patients, and possibly in pre-treatment primary tumour samples from patients entered into the clinical trial. Selenium uptake and speciation studies will identify the species mediating the effects observed. Based on the results of the above experiments, proteins that show altered expression with selenium treatment will be studied in PBMCs collected from patients in the trial. We also intend to utilise a limited proteomics approach to identify other key protein changes using stable isotope labelling with amino acids in cell culture followed by mass spectrometry. These changes will be confirmed by western blotting and/or rtPCR analysis.
The potential application of this research is to determine the role of selenium as a chemo-sensitiser and chemo-modulator. The addition of selenium to conventional chemotherapy may provide a simple way of improving efficacy and reducing toxicity. This study aims to provide insights into the mechanisms by which this may occur, and although focusing on lymphoma, will have relevance to other cancers.
The aims of the project are to; 1) identify key mechanisms by which selenium sensitises lymphoma cells to chemotherapy, 2) study selenium effects in normal cells and investigate how selenium protects against chemotherapy induced toxicity, 3) identify potential biomarkers that might be used for the clinical evaluation of selenium.
These studies will involve the use of lymphoma cell lines, primary lymphoma samples and normal tissue, including peripheral blood mononuclear cells (PBMCs), primary human keratinocytes and a normal lymphoid cell line (NC-NC). The effects of methylseleninic acid (MSA), alone and with cytotoxic drugs, will be studied using cell proliferation/viability assays, flow cytometry to investigate cell cycle and apoptotic effects and western blot analyses to determine effects on stress response proteins and signalling pathways. MSA induced changes in NF-?B activity will be measured in normal cells, in stored PBMCs from lymphoma patients, and possibly in pre-treatment primary tumour samples from patients entered into the clinical trial. Selenium uptake and speciation studies will identify the species mediating the effects observed. Based on the results of the above experiments, proteins that show altered expression with selenium treatment will be studied in PBMCs collected from patients in the trial. We also intend to utilise a limited proteomics approach to identify other key protein changes using stable isotope labelling with amino acids in cell culture followed by mass spectrometry. These changes will be confirmed by western blotting and/or rtPCR analysis.
The potential application of this research is to determine the role of selenium as a chemo-sensitiser and chemo-modulator. The addition of selenium to conventional chemotherapy may provide a simple way of improving efficacy and reducing toxicity. This study aims to provide insights into the mechanisms by which this may occur, and although focusing on lymphoma, will have relevance to other cancers.