A Ph.D. studentship (36 months) is available from 1st October 2021, under the supervision of Prof George Giamas, Biochemistry, School of Life Sciences.
PhD PROJECT
LMTK3 is an oncogenic kinase whose expression levels has been implicated in cancer cell invasion, endocrine/chemotherapy resistance, poor prognosis and overall tumour progression in different types of malignancies. We initially described LMTK3 as a regulator of Estrogen Receptor alpha (ERα) able to protect it from ubiquitin-mediated proteasomal degradation. In a cohort of BC patients (n>600), LMTK3 protein levels and intronic polymorphisms were significantly associated with disease-free and overall survival and predicted response to endocrine therapy, data we validated in an Asian cohort where we also showed that LMTK3 is associated with more aggressive tumours and chemo-resistance in BC. Moreover, we have demonstrated the contribution of LMTK3 in BC invasion and migration via cross-talk between RTKs and integrins. Additionally, we have shown an involvement of LMTK3 in miRNA biogenesis and we described a new scaffolding function of LMTK3 that results in cancer progression through chromatin remodelling. Recently, we solved the crystal structure of the LMTK3 kinase domain (LMTK3-KD) to 2.1Å resolution, determined its consensus motif and revealed that LMTK3 is a heat shock protein 90 (HSP90) client protein, requiring HSP90 for folding and stability. Moreover, using a high-throughput homogenous time-resolved fluorescence (HTRF) assay, we identified a novel, potent LMTK3 small-molecule inhibitor (C28) with a good selectivity profile. Using a range of in vitro and cell-based assays, we demonstrated that C28 binds directly to LMTK3 in an ATP-competitive, dose-dependent manner resulting in LMTK3 degradation in BC cell lines, through a mechanism of chaperone deprivation. Other groups have also published mechanistic/translational data in other tumour types/settings, validating these findings.
Since LMTK3 has been proposed as a potential new therapeutic target in breast cancer and considering its involvement in additional tumours, there is urgent need to:
A) Investigate the upstream signalling pathways implicated in LMTK3 regulation.
B) Further decipher the signalling pathways that LMTK3 is involved in and
C) Develop/optimise selective chemical tools/LMTK3 inhibitors and examine their effects in BC (in vitro/cell-based studies).
Amongst the primary objectives of this project will be to identify novel upstream pathways that are responsible for the activity of LMTK3. The identification of such genes/proteins will help us map LMTK3 in the tumour signal transduction pathways and will further lead to the development and optimisation of drugs targeting LMTK3.
A variety of biochemical, biophysical and structural biology techniques including crystallography and electron microscopy (Mancini lab) will be used for this work, in order to generate various LMTK3 truncated domains, that will be used as substrates for identifying upstream interacting proteins (e.g., kinases that are able to phosphorylate certain key residues on LMTK3 that are important for its function) and elucidate their 3D structure/properties. In parallel, combination of different cellular/molecular biology techniques as well as specific in vitro and in vivo tools/models (Giamas lab) will allow to test the significance of our findings (e.g., 2D and 3D cell-based assays as well as cancer mouse models).
In addition, considering that the Giamas lab has already developed a novel small molecule LMTK3 inhibitor (as well as other derivatives), a major issue that needs to be addressed is related to the mechanism of action of these drugs and their further optimisation. The Mancini lab will provide extensive help for this objective via their expertise in structural biology (eg. setting up different co-crystallisation studies).