Characterisation of the signalling pathways involved in cell invasion downstream of extra centrosomes

Despite the progress, cancer is still a serious challenge in medicine. Identifying the differences between tumour and normal cells is imperative to understand the disease and to develop novel selective therapeutic strategies. The presence of extra copies of a cellular organelle called centrosome is a unique feature of tumours. Indeed, the presence of extra centrosomes in tumour cells has been recognized since the late 1800s and was then proposed to be cause of malignancy. Yet, to date how centrosome amplification contributes to tumour progression is still unclear. Our recent work demonstrates that the presence of extra centrosomes can induce cell invasion in cells similarly to overexpression of known oncogenes. This finding highlights the importance that these organelles play in tumour progression. In addition, since cell invasion is one of the first steps required for metastatic dissemination of tumour cells, responsible for 90% of human cancer deaths, understanding this process is crucial.

In this research proposal we aim to determine how centrosome amplification induces cell invasion. We will use a combination of approaches to identify the signalling alterations that occur as a result of centrosome amplification. Next, we will investigate the signalling alterations that are important for invasion using sophisticated 3-D cell culture models that closely mimic the real tissues. Our results will be also validated in human breast cancer samples from patients. This is essential to establish the relevance of our findings to cancer. Importantly, this strategy has the potential for the development of novel biomarkers to identify tumours containing extra centrosomes in the clinic. This is important because we previously showed that cells with extra centrosomes have unique survival requirements and can be selectively killed. Based on our previous observations, new drugs that kill cells with extra centrosomes have been recently developed. Thus, our work will not only contribute to understand the role of centrosomes amplification in tumour progression and invasion but could also have a major impact in the clinic.

Centrosome abnormalities, and in particular centrosome amplification, are common features of human tumours. However, to date the contribution of extra centrosomes to tumour progression is still unclear. We recently found that centrosome amplification can induce invasion in non-transformed human cells, similarly to the overexpression of known oncogenes, such as ERBB2. This is in part due to RAC1 activation as a result of increased microtubule nucleation downstream of extra centrosomes. However, our preliminary data suggests that RAC1 activation alone is not sufficient to induce a robust invasive phenotype and that other signalling pathways play a role in this process. In this study, we aim to characterise the signalling alterations that are induced by centrosome amplification. To do so we will preform phosphoproteomics to identify altered phospho-sites in cells with extra centrosomes. Next, using 3D cell culture models, we will determine the signalling alterations that are important for the invasive phenotype, which will further clarify the mechanisms behind these striking morphological changes. Finally, we will test whether our findings can be recapitulated in human breast tumours using breast cancer tissue samples. This strategy has the potential for the development of biomarkers to identify tumours with extra centrosomes that would be sensitive to drugs that specifically target these cells (e.g. HSET inhibitors). We anticipate that the experiments proposed here will contribute to our understanding of how centrosome amplification impacts tumour progression. Importantly, these studies will open new areas of investigation in my laboratory regarding not only the role of centrosome amplification in cancer but also how the centrosome regulate intracellular signalling in normal cells.

Centrosome amplification is a common feature of human tumours. However, the contribution of extra centrosomes to tumour progression is still unclear. Our recent work uncovered a novel role for centrosome amplification in promoting cell invasion and the proposed project aims to identify the signalling pathways that promote invasion downstream of extra centrosomes.

- We predict that this project will generate major interest in the field of centrosomes and cancer. By dissecting the signalling alterations that occurs in cells with extra centrosomes we will contribute to the understanding of how centrosome amplification impacts tumour progression.
- This project also has the potential to uncover novel signalling pathways that are regulated by the centrosome, an aspect poorly studied. thus it will benefit the scientific community
- In addition to the scientific community, our project will also impact the wider community through the public engagement program at Barts Cancer Institute. Our press office to the local and international media will advertise the work generated in this study.
- Our laboratory participates in lab tours for the public that provides another opportunity to engage with the general public.

We previously found that cells with extra centrosomes have unique requirements for survival, including the kinesin HSET/KIFC1. Because centrosome amplification is a common feature of human tumours, these findings open a new venue for the development of selective cancer therapies. Supporting this, two independent inhibitors against HSET were recently developed. However, the use these drugs in the clinic requires an efficient method to identify tumours with extra centrosomes.

- The work described in this proposal has the potential to develop biomarkers to identify tumours with extra centrosomes. We will investigate the signalling pathways that are altered in cells with supernumerary centrosomes in human breast cancer tissue samples to test if these alterations can predict which tumours have higher percentage of centrosome amplification.
- If we succeed, our work can have a major impact in the clinic. We will develop early clinical trials with the help of the Experimental Cancer Medicine Centre at the Barts Cancer Institute. in this case, our work will have the potential to benefit cancer patients by providing an alternative therapeutic strategy to specifically kill cells with supernumerary centrosomes