Breast cancer (BC) is the most frequently diagnosed cancer and the first cause of cancer death in women worldwide. BC comprises more than 20 subtypes which present diverse genetical, morphological and clinical features. However, despite BC being a very complex and heterogeneous disease, therapeutic approaches are mainly based on pathological and clinical characteristics and the expression status of hormone receptors.
Besides, in many tumours, including BC, there is a population of undifferentiated cells which has the aptitude to self-renew maintaining their numbers, and differentiate into the many heterogeneous cells that comprise the tumor. These cells, known as “cancer stem cells (CSC)” or “tumour initiating cells”, are also characterized by being resistant to conventional cancer therapies, such as chemotherapy and radiotherapy, resulting in treatment failure which eventually leads to tumour relapses and metastases. For the reasons stated above, the current standard therapies are poorly tailored to individual patients and have been proved to be inefficient in eliminating CSCs.
Breast cancer stem cells (BCSCs) show high cellular plasticity and are capable of shifting between a proliferative epithelial-like state and a quiescent mesenchymal-like state, in a process tightly controlled by the tumour microenvironment and recently proposed to be redox-regulated.
However, redox-regulation of BCSCs plasticity is still poorly understood and the published evidence has some limitations. The results that have been obtained so far were conducted in cancer cell lines, which do not reflect the high heterogeneity present in patient tumours. Secondly, the effect of oxidant molecules has been evaluated only as an external source, and the endogenous production of these molecules by the tumor cells, which is a consequence of common radiotherapy and chemotherapy, has not been considered. Lastly, the dynamics of oxidant production by single cell types within the tumour have not yet been studied.
We hypothesize that the redox-regulated BCSC plasticity could be exploited as a vulnerability thereby potentially representing a novel BC therapy. Thus, BCSC redox state could be modulated in order to efficiently target and eliminate these cells, ultimately increasing conventional therapy effectiveness and decreasing the probability for tumour relapse and metastases.
Objectives:
The general aim of this project is to decipher redox regulation in CSC and to exploit it as a potential therapeutic target for BC. With this aim, the following specific objectives are considered:
1. To evaluate the generation of specific free radicals in BC cell lines and organoids
2. To study free radical production in BCSCs in patient-derived organoids (PDOs)
3. To understand redox dynamics and therapy response in BC PDOs
4. To modulate redox signalling in BCSCs as a potential and innovative therapeutic approach
We propose to exploit the model of BC PDOs to investigate redox signalling at single cell level. PDOs have been shown to well recapitulate the phenotypic diversity of the tissue of origin, maintaining tissue cellular heterogeneity, including stem cells. Furthermore, we plan to use for the first time genetically-encoded redox sensors, to accurately measure the production of specific free radicals by individual cells in BC PDOs, and to study the dynamics of free radical production in response to therapy. Additionally, we plan to take advantage of a newly developed chemo-genetic tool to modulate redox signalling in BCSCs and use it as an innovative therapeutic approach for the targeting and elimination of these cells.
