17 / 05 / 2022
Human relevant research for breast cancer
October is Breast Cancer Awareness Month, an annual campaign to raise awareness of the impact of breast cancer, show support for people all over the world affected by the disease, and raise money for breast cancer research and care for patients and their families.
In this article, we look at how human relevant research can be used to help us learn more about the disease, and in particular how the availability of ethically donated patient tissue allowed recent research in the FRAME Alternatives Laboratory to explore potential markers to predict patient responses to chemotherapy treatments.
Breast cancer is the most common cancer in women the UK, with one woman diagnosed every 10 minutes. Men can also be affected with around 370 men diagnosed with breast cancer every year in the UK.1 This disease is so prevalent that it is estimated one in seven women will develop breast cancer in their lifetime and that every year, around 11,500 women and 85 men will die from breast cancer in the UK.1
Treatment for breast cancer includes surgery to remove the cancerous cells, generally followed up with radiotherapy and/or chemotherapy. There are also drug therapy treatments that may be given alongside depending on the type and cause of the cancer, some of which may be taken for the rest of the patient’s life. Hormone therapies may be given to reduce the effect of oestrogen on breast tissue, and targeted drugs may be given to shrink tumours before surgery, or to reduce the chance of the cancer coming back or spreading to other parts of the body. When the cancer is not detected early it can spread to other parts of the body, causing secondary (or metastatic) cancer, and become incurable. Breast cancer most commonly spreads to the bones, brain, lungs, or liver. Whilst it cannot be cured, there are many treatments that increase survival time and relieve symptoms.
Cancer Research UK states that 76% of those diagnosed with breast cancer will survive for 10 or more years.2 Early detection of the disease is critical to survival and a core theme during Breast Cancer Awareness Month is encouraging women to check their breasts and share information on the symptoms. The treatment regime for breast cancer and the side effects of the drugs and therapies can be gruelling. Some of these treatments are precautionary in the hope they will have a preventative effect, but with no guarantee they will work.
Adjuvant chemotherapy refers to the chemotherapy that is given following surgery to remove the tumour, with the intention of preventing a relapse and the reappearance of cancerous cells.
Neoadjuvant chemotherapy (chemotherapy delivered prior to surgery) is used to downstage the tumour and reduce its size to allow surgical treatment and increase the likelihood of breast tissue preservation after the surgery. Only 20-30% of patients, however, show a full response to this particular treatment resulting in the disappearance of all invasive cancer. The remaining patients receive little benefit from undergoing the treatment and may experience significant complications because of the chemotherapy.
Animal research has historically, and in many cases still is, contributing knowledge and information to our understanding of cancer and potential treatments. Last year, over 104,000 procedures were carried out on animals for basic cancer research, and nearly 50,000 into specific human cancer projects.3 Over 99% of these procedures were carried out on mice, many of them ‘humanised’ or genetically altered to incorporate human genes into their genome (DNA). According to a 2020 paper published in Zoological Research, animal models for breast cancer should reflect tumour development from similar causes, show similar behaviour and pathology and a similar response to therapies.4 Mice do not naturally develop breast cancer in the same way, or from the same risk factors as humans. Instead, mice have been genetically modified to develop breast cancer or transplanted with breast cancer cells from human sources. Tumours can also be induced through viral infection, or the introduction of a carcinogenic chemical.5 However, human tumours are complex. Cells within an individual tumour can vary in form, metabolism, movement, and their ability to divide or spread. They also vary between patients with the same condition. It is well acknowledged in current literature that whilst each animal model has advantages and disadvantages, none can truly replicate all the aspects of human breast cancer.4, 5 This also highlights why the ability to study cancer in patients and using donated human tissue is so valuable.
It is heartening to know that alternative, non-animal research methods are also being developed and used in the study of breast cancer. Modern methods are advancing and producing more biologically-relevant tumour models. Scientists can culture human tissue to produce organoids and use bioengineering to create 3D models that can replicate the microenvironment tumour cells experience inside the body including the flow of available nutrients.6 As these models improve, they have one advantage over the use of animals: they allow the study of human tissue in a controlled environment. Whilst we may not be able to study complex biological system interactions without using animals yet, we must surely be getting closer.
FAL research project
Current research that demonstrates how cell culture techniques can shed light on possible breast cancer treatments include projects from our very own FRAME Alternatives Laboratory (FAL) at the University of Nottingham. PhD student Wichitra Asanprakit successfully completed her PhD under the supervision of Dr Andrew Bennett earlier this year, and her project was published in the British Journal of Surgery in July 2021.
The aim of Wichitra’s research was to establish whether a patient’s gene expression pattern could be used to predict whether chemotherapy prior to surgery would be successful or not. A patient is said to have a pathological complete response (pCR) when the chemotherapy removes all traces of the cancer.
A pilot study was performed using fresh frozen breast cancer biopsy specimens from 10 patients with large and locally advanced breast cancer, who all underwent chemotherapy prior to surgery. In some of these patients, the chemotherapy was completely successful, resulting in the complete disappearance of cancerous tissue (pCR). In other patients in the sample, it was not. The RNA (a copy of DNA which is then used to make proteins in the body) of the 10 patients was then analysed in a process known as genome sequencing, to see whether there was any correlation between the level of expression of specific genes and the successful outcome of the treatment. This initial study revealed that expression of the polymeric immunoglobulin receptor (PIGR) gene, was significantly increased in women where the chemotherapy was successful. The PIGR gene codes for the production of a protein found in cell membranes. This protein forms a receptor called the polymeric immunoglobulin receptor (pigR). Gene expression is a measure of how much product is being made by the gene in a cell. This can vary between cell types and people. The results of this study therefore suggested that higher levels of the pigR receptor protein in the breast cancer cells of patients may be a biomarker that indicates whether chemotherapy treatment prior to surgery would be effective.
After these initial findings, Wichitra increased the scale of her research to include tissue from a larger cohort of breast cancer patients to further investigate whether increased PIGR expression in cells could be used to predict whether neoadjuvant chemotherapy would successfully work or not.
The ultimate goal of this research is to translate the findings into clinical practice. If a predictive factor for prognosis after chemotherapy can be found, it will undoubtedly impact breast cancer patient care through more personalised targeted treatment. The potential benefits of receiving the treatment could be predicted and weighed against the potential harm caused by the serious side effects of chemotherapy. This would help improve patient outcomes, safety and quality of life, as well as reduce healthcare costs in the NHS.
Wichitra’s hard work during her time in the FAL has resulted in the publication of three articles in the British Journal of Surgery earlier this summer. All her research was underpinned by the use of human tissue and patient-based research, which FRAME believes has far greater potential to be relevant to human health than most animal-based research.
In the first paper, the effect of the microenvironment around the tumour on the expression of PIGR was investigated. A protein causing an inflammatory response (interleukin-1β), that is secreted by a particular type of white blood cell (M1 Macrophage), was found to enhance PIGR expression in breast cancer cells.
- O9 M1 macrophages evoke an increase in PIGR expression in MDA-MB468 breast cancer cells through interlukin-1β | British Journal of Surgery | Oxford Academic (oup.com)
In the next paper, existing breast cancer cell lines were studied. A viral vector was used to increase PIGR expression in these cells to see how it affected the cell behaviour and sensitivity.
- O25 Expression of polymeric immunoglobulin receptor (PIGR) and the effect of PIGR overexpression on breast cancer cells | British Journal of Surgery | Oxford Academic (oup.com)
The final paper looks at whether the increased expression of PIGR in some breast cancer patients contributed to the success of the neoadjuvant chemotherapy and survival rates, and ultimately whether there is potential for PIGR gene expression to be used as a measure to predict the success of the treatment.
- O24 Predictive and prognostic roles of polymeric immunoglobuilin receptor in breast cancer | British Journal of Surgery | Oxford Academic (oup.com)
This research would not have been possible without the availability of tissue from breast cancer patients. These individuals agreed to allow their tissue to be used in research despite facing the challenging circumstances of a breast cancer diagnosis and possibility of the intensive treatment regimes. Human tissue can be ethically donated through hospitals and is vital for allowing studies like this that could help lead to future scientific breakthroughs.