Leeds University (Dr Thorne)
Breast Cancer UK has awarded a grant to Dr James Thorne, at Leeds University, to support his research which aims to develop a new method (using mass spectrometry) to measure accumulation of oxysterols in human breast tissue.
Preventing breast cancer recurrence through reducing dietary intake of oxidized cholesterol: An analytical tool.
James L Thorne (PI), Hanne Røberg-Larsen, Lisa Marshall and Thomas A Hughes
Some oxysterols can interfere with endocrine signalling and may be formed enzymatically, at sites of hypoxia (low oxygen in tissues), or when dietary cholesterol is exposed to high temperatures during frying or food processing. Emerging evidence indicates that tumours that develop in a high oxysterol environment may be more resistant to chemotherapy and more likely to spread (metastasize).
Oxysterols can promote oestrogen positive breast tumour growth through activation of the oestrogen receptor, and increase metastasis of triple negative breast tumours through other routes. Oxysterols can be readily removed from the diet and the activity of oxysterols produced in the body may be repressed by a diet rich in plant-sterols (e.g. vegetable oils, nuts, grains, peas and beans).
The project will aim to develop a method that can detect the accumulation of several different oxysterols in breast tissue samples. This will complement on going work that is investigating whether high oxysterol content of tumours increases the likelihood of unsuccessful cancer treatment. The work also aims to demonstrate if oxysterol concentrations in breast tumours can be reduced by dietary changes.
The research will begin in July 2016, and is expected to continue for around a year. Dr Thomas Hughes and Dr Lisa Marshall will also be involved in the project.
Description of results by Dr Thorne
Oxysterols are a group of signaling molecules that are derived from cholesterol through auto-oxidation during cooking (e.g. 25-OHC, 7-KC) or by enzymatic synthesis (22R-OHC, 24S-OHC, 25-OHC, 27-OHC, 24,25-EC). Some of these cholesterol oxidation products accumulate in breast cancer tissue and are elevated in the circulation of individuals with metastatic breast cancer and other conditions that risk factors for breast and other cancers (obesity, metabolic syndrome, hypercholesterolemia). Importantly, oxysterols are emerging as functional drivers and circulating biomarkers of breast cancer and in vitro experiments reveal they enhance metastasis and chemoresistance. Oxysterols may therefore be therapeutic targets in ER+ and TNBC disease and simple dietary or pharmacological interventions could improve disease free survival.
In this pilot grant, we set out to develop and apply a Liquid Chromatography Mass-Spectrometry (LC-MS/MS) method to detect a panel of oxysterols in human breast tumours. An important objective was that the sample requirements (size/volume of tissue, storage, processing conditions) should be compatible with existing surgical, diagnostic and analytical procedures. Secondary aims were to measure the concentrations of oxysterols in different breast tumour subtypes and assess oxysterol content in a panel of cell lines. Our method was able to detect 5 out of the 6 proposed oxysterols in primary tumour samples obtained from the Leeds Breast Tissue Bank and in a panel of breast cancer and fibroblast cell lines. Importantly, the tumour volume requirements were optimised so that analysis of 10 different sterols could be performed on tissue equivalent to less than 20% of a single needle core biopsy (circa 10mg of tissue).
We now intend to apply the LC-MS/MS method to a fully powered cohort of tumour samples with matched blood samples. In subsequent work we will ask the following questions: i) Is the oxysterol mixture quantitatively or qualitatively different between ER-positive and ER-negative breast tumours, ii) Are oxysterols predictive biomarkers of relapse/response to therapy, iii) Are oxysterols from non-cancer “host cells” driving cancer initiation/progression, and iv) Can dietary repression of eswaoxysterol signaling reduce primary or secondary breast cancer incidence?
Summary of results
Dr Thorne and colleagues developed a novel way of measuring 5 different oxysterols in breast tissue samples and cell culture. Crucially, it only requires a very small amount of tissue; less than that from a typical biopsy.
See here for a review that focuses on phytosterols and breast cancer prevention by Dr Thorne and colleagues. Faikh, O. et al. (2018). Exploring the biophysical properties of phytosterols in the plasma membrane for novel cancer prevention strategies. Biochimie Available online 3 May 2018.