Defining the role of FOSL2 in molecular adaptation to hypoxia in colorectal cancer

Colorectal cancer is the third most common cancer in both men and women and leads to 500,000 deaths a year worldwide. As tumours grow they need blood vessels to transport oxygen and nutrients into the tumour. However tumours often outgrow their blood supply and contain regions that do not have enough oxygen or nutrients. These regions are frequently found in colorectal cancer. The colorectal tumour cells in these areas change at a molecular level so that they can survive in these "starving" conditions. The changes that occur make the cells resistant to chemotherapy and radiotherapy and make it more likely the tumour will spread. Patients with tumours that contain these regions of low oxygen are less likely to survive than patients without these regions. Thus it is important to find new alternative ways of killing cells in these regions with not enough oxygen or nutrients that can be used in combination with current approaches that are effective at killing the other regions. We think that we have found a new way of stopping the cells from adapting to the lack of oxygen and nutrients. In my previous work I tested the effect of interfering with 6000 genes and examined the effect of each of these on how cells survived and grew in an environment lacking oxygen. I also investigated whether patients with higher expression of any of these 6000 genes were less likely to survive. I found that 52 genes fit into both these categories inhibiting survival and growth in regions of low oxygen and also where high expression in a patients tumour meant the patient was less likely to survive. Interfering with one of these genes had the greatest effect on stopping tumour cells adapting to regions of low oxygen, preventing them from surviving and growing in these conditions in all of the tests. We think that by interfering with this gene we are inhibiting the changes that occur at a molecular level in response to the lack of oxygen and nutrients. We want to investigate the link between high expression of the protein this gene makes and the regions of low oxygen and colorectal cancer patient survival. This will let us see if high expression of this protein could be used to help understand which patients may need more aggressive treatments. We want to investigate how this gene helps tumour cells grow and survive in hypoxia. We will also examine the extent of the effect at the molecular level and at a cellular level to investigate the exact consequence of targeting this protein on colorectal cancer regions which lack of oxygen and nutrients. This will provide evidence for developing new inhibitors to target this therapy-resistant region of colorectal tumours.

Colorectal cancer is the third most common cancer in both men and women and leads to 500,000 deaths a year worldwide. 1 in 3 colorectal tumours contains regions of low oxygen (hypoxia) that are found in most solid tumour types. Hypoxia is caused by high tumour metabolic and proliferative rates and aberrant vascularization. Clinically hypoxia is associated with worse patient survival and chemotherapy and radiotherapy resistance. Hypoxia also induces metastasis, a major cause of cancer death. Identifying novel ways to target hypoxic tumours is a key objective to improve therapeutic response for these patients. We carried out an unbiased induced-essentiality functional shRNA screen to identify novel regulators of hypoxic tumour cell survival in 2D and 3D cell-culture. FOSL2 was the top hit in these analyses where FOSL2 knockdown reduced cell viability in hypoxia. Using published colorectal cancer expression array data we identified that high FOSL2 expression is associated with worse patient survival. We have shown that FOSL2 expression is increased in hypoxia and that knockdown reduces the expression of the key hypoxia regulated gene CA9. FOSL2 binds with Jun proteins to form variants of the transcription factor complex activator protein-1 (AP-1). We hypothesise that FOSL2 promotes hypoxic cell growth and survival via transcriptional regulation of target genes and we will investigate this using 2D, 3D and in vivo xenograft models. We will identify the HIF1a and HIF2a -dependent and -independent gene expression roles of FOSL2. Furthermore a key FOSL2 regulated-transcript will be investigated for its mechanistic role in hypoxic tumour growth and survival. We will examine the associations between FOSL2 and patient survival, and hypoxia using colon cancer TMA. We will investigate FOSL2 as a key regulator of molecular adaptation to the hypoxic tumour microenvironment and as a target for development of inhibitors against the therapy resistant hypoxic tumour microenvironment.

Direct beneficiaries will include, the academic community as proposed in the academic beneficiaries section, the scientists employed and funded by the research grant, the biotech and pharmaceutical industry, the University of Nottingham and long term colorectal cancer patients and patients with additional types of solid tumour which contain regions of hypoxia.
The scientists employed and funded by the grant to perform the research will directly benefit from training that they receive to do the work. The plan for the research is to hire 2 experienced researchers to fill the post-doc and bioinformatician-post-doc positions, however the breadth of research techniques and the variety of scientific challenges involved in the work necessitate that both individuals will require additional training and support. The skills developed in both positions are in demand in both industry and also academia and will provide a strong skill set base for their future careers.
The plan for the research is to identify and functionally validate 2 targets that are required for tumour cell growth and survival in hypoxia. Hypoxia is associated with poor patient outcome and chemotherapy and radiotherapy resistance in colorectal cancer and most other solid tumour types. The resistance of hypoxic regions of solid tumours to therapeutic regimes is a current stumbling block in cancer therapy. Therefore identifying novel ways to target hypoxic regions of tumours that induce apoptosis is key to overcoming therapy resistance and improving patient survival in combination with current treatment strategies. Further work will investigate the effect of combining such targeting with other chemotherapy and radiotherapy strategies in preclinical investigations. Furthermore this work will assess the utility of FOSL2 as a biomarker for poor patient outcome. These investigations will also be developed further examining FOSL2 not only as a prognostic indicator but also as a possible companion biomarker for any FOSL2 targeting small molecular inhibitor.
These are key long-term aim for the project. This will directly benefit the University of Nottingham, which will receive financial benefits from any patents filed upon the work based on its future commercialisation. Towards the mid-point/end of the project we will establish collaborations to identify novel inhibitors to target FOSL2 and FOSL2 regulated genes and pathways as a method of targeting the hypoxic tumour microenvironment (as described in the academic beneficiaries section). This would lead to investing in drug development projects with pharmaceutical companies or through establishing a spin-out company as discussed in the pathways to impact document. This will in the medium-term directly financially benefit the pharmaceuticals and biotech industry.
Long-term the work will have significant impact on the colorectal cancer patients and patients of other solid tumour types which contain regions of tumour hypoxia, by providing molecular targeted therapies to increase survival in these patients which currently have a worse outcome.
The main indirect Beneficiary is the UK economy. As recognised by organisations such as Campaign for Science and Engineering (CaSE), the UK has a strong record in science research despite low investment compared to other leading scientific nations. Maintaining high levels of high quality research is key in attracting inward financial investment into the UK. As stated by CaSE "Research and Innovation underpins a strong economy". It is therefore key for retaining the presence of the UK pharmaceuticals industry to have cutting edge high impact science in the UK with long-term clinical impact goals. Furthermore the training received by the 2 post doc scientists will also add to the UK economy as the skill sets developed during the term of the positions will increase the expertise available to academic and/or pharmaceutical institution