Ludwig Cancer Research DPhil Studentships - “Manipulating hypoxia signalling to influence (cancer) stem cell behaviour”

The importance of stem cells in normal development, regeneration after tissue damage and tumour growth, metastasis and treatment resistance is increasingly appreciated. The fundamental property of these cells is their ability to self-renew but also to divide asymmetrically with one daughter cell self-renewing whilst the other goes on to produce more differentiated progeny. The factors that control whether a stem cell maintains “stemness” or begins to differentiate are complex. This has led to the concept of a stem cell niche, a particular location providing a combination of environmental factors that maintains “stemness”. When cells are in this niche they stay as relatively slowly dividing, treatment resistant, stem cells but when they move elsewhere they proliferate more rapidly, perhaps returning to a stem phenotype if they re-enter a stem cell niche.

As tumour cells proliferate their metabolic demands outstrip the ability of local blood vessels to supply oxygen and nutrients and remove waste products. In turn, signalling pathways are activated which encourage the ingrowth of new blood vessels to generate the tumour microcirculation, but generally hypoxia remains as a common feature of tumours. Interestingly, hypoxia is seen to be one important component of the stem cell niche and whilst much tumour therapy to date has been directed against eliminating the bulk of the tumour, there is an increasing realisation that for cure the stem cells have to be eliminated too. There is clear evidence that the degree of hypoxia is inversely correlated with prognosis in a wide variety of tumour types, reflecting both increased resistance to chemotherapy and radiotherapy, but also innately more aggressive cancer cell behaviour, arguably driven by the cancer stem cells.

Over the last 25 years our group has worked extensively on hypoxia signalling pathways, identifying the widespread nature of these pathways and the underlying sensing and signalling components1. In outline, three related transcription factors, HIF-1, -2 and -3 are controlled by, but differentially sensitive to, four related oxygen-dependent HIF hydroxylases (prolyl hydroxylases 1-3 (PHD1-3) and the asparaginyl hydroxylase, FIH). Whilst tumour growth is enhanced overall by an intact HIF system, further dissection reveals contrasting isoform-specific effects of HIF-1 and HIF-2 both in experimental tumours and naturally arising cancers2.

Based on this knowledge, and using doxycycline-inducible shRNA expression3, we have produced both in vivo models and tumour cell lines in which we can inducibly and – importantly - reversibly, induce or repress key components of the hypoxia signalling pathway. This studentship will focus on using these, and newly generated, reagents to manipulate the hypoxia signalling pathway in the tumour cell, the host, or both, in a timed manner to unravel the complex network of interactions between host and tumour cells with regard to the hypoxia signalling pathway. The processes of tumour initiation, growth, invasion and metastasis will be considered separately and interventions on the hypoxia signalling pathways will be tested alone and in combination with existing chemotherapy and radiotherapy regimens. Parallel work is developing isoform specific inhibitors of the various HIF hydroxylases and testing their effects in vivo, including balancing their delivery to host or tumour cells. Once the shRNA-mediated genetic interventions have delineated the most promising treatment targets for different phases of cancer growth, the most promising small molecule inhibitors will be tested to see whether they confer similar advantageous effects in retarding tumour growth and ultimately leading to cure.

The research project will involve a wide range of basic and advanced molecular/cellular biology and in vivo techniques, including but not limited to:
- Generation of genetically-modified cell lines and animals (including by CRISPR/Cas9 genome engineering)
- DNA cloning, western blotting and focussed RNAi screens
- FACS
- Transgenic breeding, genotyping,
- In vivo tumour models
- Monitoring of tumour growth and behaviour by (functional) imaging
- Confocal imaging and immunohistochemistry
- Analysis of drug action in vivo

We are seeking an exceptional student with a fascination for molecular cancer biology, “systems level” thinking and a willingness to compete at the highest international level. The successful candidate is expected to have good communication skills, attention to detail and an ability to work both independently and as part of a team. A strong track record in a relevant subject is essential and experience in pharmacology, medicinal chemistry or image analysis would be considered advantageous.