Periodic Reporting for period 3 - BRCA-ERC (Understanding cancer development in BRCA 1/2 mutation carriers for improved Early detection and Risk Control)
Période du rapport: 2020-11-01 au 2022-04-30
The BRCA-ERC programme aims to better understand the factors contributing to increased risk for breast and ovarian cancer in BRCA1/2 germline mutation carriers. Tissue specific disease penetrance of the BRCA1/2 mutation remains partly understood and we aim to learn more through the study of multiple body systems, specifically examining the contribution of factors which have an indirect impact (cell-non autonomous) on cancer development in women with BRCA1/2 mutations with a specific focus on epigenetic processes. Our ultimate aim is to uncover novel insights as to the systemic contributors of heightened risk in BRCA1/2 mutation carriers that can then be targeted to advance preventive measures.
Our research to date has uncovered numerous important findings that can be categorised into 4 main areas: 1) Understanding the impact of BRCA mutations on systems biology, 2) Development of tests and tools to risk predict, early detect cancer and monitor preventive measures, 3) Increasing our understanding of the contribution of epigenetics in the promotion of carcinogenesis, and 4) Assess the opportunity to interfere with cancer-driving factors in BRCA mutation carriers to non-surgically prevent cancer formation.
We have shown that multiple cell-non autonomous factors are significantly associated with increased cancer risk in BRCA1/2 carriers, including increased systemic hormone levels as a function of the menstrual cycle, decreased immune cell cytotoxic activity, heightened hypoxic conditions in high risk tissues, and an altered microbiome community in the cervix and vagina (the latter is detailed in our recently published work: Lancet Oncol. 2019 Aug;20(8):1171-1182).
We have also developed a series of novel epigenetic tests with which to risk predict breast and ovarian cancer and monitor associated cell non-autonomous risk factors. Close examination of the epigenetic features comprising these tests has revealed the hugely significant finding that epigenetic reprogramming in normal high risk tissue cells towards a cell type identity facilitates invasion into surrounding and supporting tissues.
In conjunction with our novel research findings, we continue to collaborate with key international consortia specialising in personalised early detection and prevention of breast cancer. To this end, in June 2019 we held The European Collaborative on Personalised Early Detection and Prevention of Breast Cancer (ENVISION) Network Conference in Hall in Tirol, Austria. In this consensus conference, experts in stratified risk prediction and health screening discussed and identified key strategies to realise the implementation of evidence-based personalised interventions in order to improve the benefits and reduce the harms of existing screening programmes. Priority areas identified were: (i) breast cancer subtype-specific risk assessment tools applicable to women of all ancestries; (ii) intermediate surrogate markers of response to preventive measures; (iii) novel non-surgical preventive measures to reduce the incidence of breast cancer of poor prognosis, and, (iv) to combine hybrid effectiveness-implementation research with modelling studies to evaluate the long-term population outcomes of risk-based early detection strategies. The implementation of such programmes would require healthcare systems to be open to learning and adapting, the engagement of stakeholders, and tailoring to societal norms and values, while addressing ethical, legal and social aspects.
Our research to date has uncovered numerous important findings that can be categorised into 4 main areas: 1) Understanding the impact of BRCA mutations on systems biology, 2) Development of tests and tools to risk predict, early detect cancer and monitor preventive measures, 3) Increasing our understanding of the contribution of epigenetics in the promotion of carcinogenesis, and 4) Assess the opportunity to interfere with cancer-driving factors in BRCA mutation carriers to non-surgically prevent cancer formation.
We have shown that multiple cell-non autonomous factors are significantly associated with increased cancer risk in BRCA1/2 carriers, including increased systemic hormone levels as a function of the menstrual cycle, decreased immune cell cytotoxic activity, heightened hypoxic conditions in high risk tissues, and an altered microbiome community in the cervix and vagina (the latter is detailed in our recently published work: Lancet Oncol. 2019 Aug;20(8):1171-1182).
We have also developed a series of novel epigenetic tests with which to risk predict breast and ovarian cancer and monitor associated cell non-autonomous risk factors. Close examination of the epigenetic features comprising these tests has revealed the hugely significant finding that epigenetic reprogramming in normal high risk tissue cells towards a cell type identity facilitates invasion into surrounding and supporting tissues.
In conjunction with our novel research findings, we continue to collaborate with key international consortia specialising in personalised early detection and prevention of breast cancer. To this end, in June 2019 we held The European Collaborative on Personalised Early Detection and Prevention of Breast Cancer (ENVISION) Network Conference in Hall in Tirol, Austria. In this consensus conference, experts in stratified risk prediction and health screening discussed and identified key strategies to realise the implementation of evidence-based personalised interventions in order to improve the benefits and reduce the harms of existing screening programmes. Priority areas identified were: (i) breast cancer subtype-specific risk assessment tools applicable to women of all ancestries; (ii) intermediate surrogate markers of response to preventive measures; (iii) novel non-surgical preventive measures to reduce the incidence of breast cancer of poor prognosis, and, (iv) to combine hybrid effectiveness-implementation research with modelling studies to evaluate the long-term population outcomes of risk-based early detection strategies. The implementation of such programmes would require healthcare systems to be open to learning and adapting, the engagement of stakeholders, and tailoring to societal norms and values, while addressing ethical, legal and social aspects.
Our research can be classified under 4 main areas: 1) Understanding the impact of BRCA mutation on systems biology, 2) Development of tests and tools to risk predict and early detect cancer, 3) Increasing our understanding of the contribution of epigenetics in the promotion of carcinogenesis, and 4) Assess the opportunity to interfere with cancer-driving factors in BRCA mutation carriers to non-surgically prevent cancer formation.
1. Understanding the impact of BRCA mutation on systems biology
We performed several studies that in combination allow us to understand how germline mutations, such as BRCA1/2, can alter numerous body systems that in turn modulate risk. We observed that BRCA carriers have higher levels of progesterone and oestrogen exposure over the course of the menstrual cycle compared to women without the mutation. High estradiol levels in the first phase of the menstrual cycle (early follicular or ‘EF’ phase) increase expression of progesterone receptors in hormone-sensitive cells, which are consequently exposed to high progesterone levels in the second phase (early luteal or ‘EL’ phase). This suggests that the system is highly progesterone-dominated in BRCA carriers. Progesterone is known to trigger expansion of the ER-ve/PR-ve luminal progenitor cells - considered the cell of origin of triple negative breast cancer (TNBC).
We are currently studying the natural killer (NK) cytotoxic activity in BRCA carriers when comparing levels across the entire menstrual cycle and assess the dynamic fluctuation of NK activity between the different phases of the menstrual cycle and under hypoxic conditions. Given NK cells are recognised as key immune moderators of tumour surveillance, these data will allow us to understand whether BRCA1 mutation carriers are potentially immuno-compromised in this regard.
Using various tissue samples and cell culture experiments, we are studying the role of hypoxia in the development of ovarian cancer, particularly in women with a BRCA mutation and how this affects the cells’ software, the epigenome.
Finally, we have provided evidence of an association of microbial diversity in the cervix-vagina that is associated with increased cancer risk. We have found that in women with an ovarian cancer and in women with a BRCA1 mutation who have not yet developed an ovarian cancer, the vaginal microbiome is far more frequently dominated by the microbiome community Type ‘O’ – a microbiomial community type that is not dominated by beneficial lactobacilli species.
These important data demonstrate the effect of germline mutations on multiple body systems and therefore the combined contribution of multiple cell non-autonomous factors to cancer risk in women with BRCA mutations.
2) Development of tests and tools to risk predict and early detect cancer
We are in the process of producing separate DNAme tests and tools that can be further validated with the goal being to implement them into clinical practice:
i) Breast cancer risk: we are developing an epigenetic test in cervical smear samples which is able to identify (and likely predict the future risk for) breast cancer. This test is also likely to identify women with a germline mutation in the BRCA1 and BRCA2 genes.
ii) Ovarian cancer risk: we are in the final stages of developing a test, based on a DNA methylation signature, which is able to identify women with (and likely predict future risk for) ovarian cancer. We are currently assessing whether the signature is reflective of a systemic epigenetic differentiation defect.
iii) Epigenetic test reflective of the vaginal microbiome: due to our finding that the cervico-vaginal microbiome is an ovarian cancer risk factor and highly prevalent particularly in young women with a BRCA1 mutation, we are currently developing a test which purely uses a DNA methylation signature from a cervical smear sample to enable identification of women with a non-lactobacilli dominated microbiome.
3) Increasing our understanding of the contribution of epigenetics in the promotion of carcinogenesis.
Through the development and assessment of various epigenetic indices, we learned more concerning the development of cancer on an epigenetic level. In particular, the aforementioned cancer risk tests appear to suggest that the human cells’ epigenome is susceptible to a large number of factors that reprogram the epigenome and thereby changes the identity of the cells at least at the level of the epigenome, which will then lead to cancer predisposition. These findings are hugely insightful in revealing how the epigenome contributes to cancer development in the early stages, i.e. we posit that epigenetic re-programming allows cells to adopt a new cellular identity reflective of the surrounding tissues into which they subsequently invade.
4) Assess the opportunity to interfere with cancer-driving factors in BRCA mutation carriers to non-surgically prevent cancer formation.
We have developed epigenetic tests in the breast tissue that allow the proportion of “older stem cells” to be assessed which have a higher tendency for cancer formation. In addition, we have developed a signature that can assess the proportion of various epithelial and non-epithelial cells in a breast biopsy. These two signatures allow us to monitor changes in the breast as a function of exposure to potential cancer preventive drugs such as Mifepristone (a progesterone antagonist), which, at least in mice, have shown great potential in reducing the incidence of poor prognostic BRCA-mutation driven breast cancers.
1. Understanding the impact of BRCA mutation on systems biology
We performed several studies that in combination allow us to understand how germline mutations, such as BRCA1/2, can alter numerous body systems that in turn modulate risk. We observed that BRCA carriers have higher levels of progesterone and oestrogen exposure over the course of the menstrual cycle compared to women without the mutation. High estradiol levels in the first phase of the menstrual cycle (early follicular or ‘EF’ phase) increase expression of progesterone receptors in hormone-sensitive cells, which are consequently exposed to high progesterone levels in the second phase (early luteal or ‘EL’ phase). This suggests that the system is highly progesterone-dominated in BRCA carriers. Progesterone is known to trigger expansion of the ER-ve/PR-ve luminal progenitor cells - considered the cell of origin of triple negative breast cancer (TNBC).
We are currently studying the natural killer (NK) cytotoxic activity in BRCA carriers when comparing levels across the entire menstrual cycle and assess the dynamic fluctuation of NK activity between the different phases of the menstrual cycle and under hypoxic conditions. Given NK cells are recognised as key immune moderators of tumour surveillance, these data will allow us to understand whether BRCA1 mutation carriers are potentially immuno-compromised in this regard.
Using various tissue samples and cell culture experiments, we are studying the role of hypoxia in the development of ovarian cancer, particularly in women with a BRCA mutation and how this affects the cells’ software, the epigenome.
Finally, we have provided evidence of an association of microbial diversity in the cervix-vagina that is associated with increased cancer risk. We have found that in women with an ovarian cancer and in women with a BRCA1 mutation who have not yet developed an ovarian cancer, the vaginal microbiome is far more frequently dominated by the microbiome community Type ‘O’ – a microbiomial community type that is not dominated by beneficial lactobacilli species.
These important data demonstrate the effect of germline mutations on multiple body systems and therefore the combined contribution of multiple cell non-autonomous factors to cancer risk in women with BRCA mutations.
2) Development of tests and tools to risk predict and early detect cancer
We are in the process of producing separate DNAme tests and tools that can be further validated with the goal being to implement them into clinical practice:
i) Breast cancer risk: we are developing an epigenetic test in cervical smear samples which is able to identify (and likely predict the future risk for) breast cancer. This test is also likely to identify women with a germline mutation in the BRCA1 and BRCA2 genes.
ii) Ovarian cancer risk: we are in the final stages of developing a test, based on a DNA methylation signature, which is able to identify women with (and likely predict future risk for) ovarian cancer. We are currently assessing whether the signature is reflective of a systemic epigenetic differentiation defect.
iii) Epigenetic test reflective of the vaginal microbiome: due to our finding that the cervico-vaginal microbiome is an ovarian cancer risk factor and highly prevalent particularly in young women with a BRCA1 mutation, we are currently developing a test which purely uses a DNA methylation signature from a cervical smear sample to enable identification of women with a non-lactobacilli dominated microbiome.
3) Increasing our understanding of the contribution of epigenetics in the promotion of carcinogenesis.
Through the development and assessment of various epigenetic indices, we learned more concerning the development of cancer on an epigenetic level. In particular, the aforementioned cancer risk tests appear to suggest that the human cells’ epigenome is susceptible to a large number of factors that reprogram the epigenome and thereby changes the identity of the cells at least at the level of the epigenome, which will then lead to cancer predisposition. These findings are hugely insightful in revealing how the epigenome contributes to cancer development in the early stages, i.e. we posit that epigenetic re-programming allows cells to adopt a new cellular identity reflective of the surrounding tissues into which they subsequently invade.
4) Assess the opportunity to interfere with cancer-driving factors in BRCA mutation carriers to non-surgically prevent cancer formation.
We have developed epigenetic tests in the breast tissue that allow the proportion of “older stem cells” to be assessed which have a higher tendency for cancer formation. In addition, we have developed a signature that can assess the proportion of various epithelial and non-epithelial cells in a breast biopsy. These two signatures allow us to monitor changes in the breast as a function of exposure to potential cancer preventive drugs such as Mifepristone (a progesterone antagonist), which, at least in mice, have shown great potential in reducing the incidence of poor prognostic BRCA-mutation driven breast cancers.
To date, we have gained significant new insight into why and how women with a BRCA mutation develop breast and ovarian cancer. We have learned that a large number of factors are altered by a germline BRCA mutation (i.e. hormonal balance, immune cells, microbiomial composition, etc.) and that these factors most likely affect the actual cells in the breast and Fallopian Tube, which eventually form breast and ovarian cancers, respectively. By the project’s culmination, we hope to have gained a thorough understanding as to how these factors (i) contribute to cancer formation, (ii) can be modulated, and whether these insights also apply to women who develop these cancers in the absence of a BRCA mutation.