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Genetic determinants promoting resistance to BCR-loss in B-cell lymphomas

Project description

Genetic determinants of resistance in BCR-negative B cell lymphomas

B cell receptor (BCR) signalling is crucial for normal B cell development and supports the survival and growth of malignant B cells in patients with B cell leukemias or lymphomas. Loss of BCR in lymphoma B cells leads to attenuated PI3K/AKT signalling and altered Myc-dependent transcriptional regulation, resulting in a competitive disadvantage in BCR-deficient lymphoma cells. The EU-funded BCRlossToBWinner project proposes to investigate whether FOXO1 mutations are able to provide resistance to BCR-loss in transformed B cells by favouring the activation of PI3K/AKT, SAPK/JNK or other signalling pathways. The research will help to identify novel factors promoting independence from BCR signalling as the therapeutic targets for the treatment of B cell lymphomas resistant to BCR-specific inhibitors.

Objective

Loss of B-Cell Receptor (BCR) in lymphoma B cells leads to attenuated PI3K/AKT signaling and altered Myc-dependent transcriptional output, resulting in a competitive disadvantage in BCR-deficient lymphoma cells. The acquisition of genetic events restoring signaling competence is sufficient to improve cellular fitness in BCR-deficient lymphomas. A fraction of Non-Hodgkin-B-cell lymphomas carry missense mutations in FOXO1, a transcription factor essential during B cell development, and a main target of the PI3K/AKT pathway, which relays survival signals downstream of the BCR. In preliminary studies, we found that cells with FOXO1 mutations rewire their signaling status showing a) activation of stress-activated protein kinases (SAPKs) and PI3K/AKT, b) altered responses to key upstream receptors, such as CD40 and BCR, and c) improved fitness. In this context, I propose to investigate whether FOXO1 mutations are able to provide resistance to BCR-loss in transformed B cells, by favoring the activation of PI3K/AKT, SAPK/JNK (and potentially other) signaling pathways. This hypothesis will be tested using mouse and human models that allow conditional deletion of the BCR in FOXO1 mutant B cells, determining whether expression of FOXO1 mutations is: a) sufficient to release normal B cells from BCR-dependency, and b) able to restore competitive fitness to BCR-deficient lymphomas. Moreover, combining CRISPR/Cas9 and chemical screenings, I propose to identify novel factors sustaining the growth of lymphoma cells that lost BCR expression. Overall, this research proposal will address relevant, yet unanswered questions in the biology of B cell lymphomas, providing a better understanding into the complexity of signaling competence in normal and transformed B cells, and identifying novel factors promoting independence from BCR signaling, to be exploited as therapeutic targets for the treatment of B cell lymphomas resistant to BCR-specific inhibitors.

Fields of science (EuroSciVoc)

Keywords

Programme(s)

Topic(s)

Funding Scheme

MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)

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Call for proposal

(opens in new window) H2020-MSCA-IF-2019

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Coordinator

IFOM-ISTITUTO FONDAZIONE DI ONCOLOGIA MOLECOLARE ETS
Net EU contribution
€ 70 713,66
Address
VIA ADAMELLO 16
20139 Milano
Italy
Region
Nord-Ovest Lombardia Milano
Activity type
Research Organisations
Links
Total cost
€ 70 713,66

Participants (1)