FOXO1-GAB1 axis regulates homing capacity and tonic AKT activity in chronic lymphocytic leukemia: novel therapeutic target

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F65269705%3A_____%2F21%3A00075118" target="_blank" >RIV/65269705:_____/21:00075118 - isvavai.cz</a>

Result on the web

<a href="https://journals.lww.com/hemasphere/Citation/2021/06002/EHA2021_Virtual_Congress_Abstract_Book.1.aspx" target="_blank" >https://journals.lww.com/hemasphere/Citation/2021/06002/EHA2021_Virtual_Congress_Abstract_Book.1.aspx</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1097/HS9.0000000000000566" target="_blank" >10.1097/HS9.0000000000000566</a>

Result language

angličtina

Original language name

FOXO1-GAB1 axis regulates homing capacity and tonic AKT activity in chronic lymphocytic leukemia: novel therapeutic target

Original language description

Background: CLL cell recirculation between peripheral blood and immune niches plays an important role in CLL biology. However, it remains largely unknown how precisely CLL cells regulate their homing or how they balance survival in peripheral blood and the decision to return to immune niches. Aims: We aim to identify and functionally characterize novel regulators of CLL cell migration. Methods: We performed transcriptome profiling (RNAseq, Illumina) of CXCR4/CD5 intraclonal CLL cell subpopulations (n=20). GAB1 function was investigated by in vitro migration assays and in vivo migration in NSG mice (GAB1-knockout MEC1 cells or siRNA transfected CLL cells). The adaptation to BCR inhibitors was analyzed in CLL samples obtained before and during ibrutinib therapy (pre vs. week 5-12, n=22). Results: CXCR4/CD5 subpopulations have been suggested as a model distinguishing CLL cells ready to re-enter immune niches (CXCR4brightCD5dim) versus recent emigrants from lymph nodes (CXCR4dimCD5bright) (Calissano et al. 2011). Indeed, intravenous injection of sorted CXCR4/CD5 subpopulations into NSG mice revealed increased migration capacity of CXCR4brightCD5dim cells into the spleen (n=6, P=0,02). Analysis of CXCR4/CD5 subpopulations by RNAseq (n=20) identified 147 migration-related differentially expressed genes, among which we noted upregulation of GAB1 (2-fold) in CXCR4brightCD5dim cells. GAB1 has been previously suggested as a cell migration regulator in non-immune cells (Vasyutina et al. 2005). GAB1-knockout in MEC1 B cells largely inhibited their migration capacity towards chemokines SDF1, CXCL13, or conditioned media produced by bone marrow stromal cells (CMhMSC). Similar results were obtained with siRNA against GAB1 in CLL cells (all P&lt;0.01). Importantly, GAB1 knockout or silencing led to clearly impaired migration of malignant B cells to the spleen of NSG mice (P&lt;0.05, n=14; Fig.A,B). Treating cells with SDF1, CXCL13, or CMhMSC led to rapid (within minutes) GAB1 phosphorylation at activating tyrosines, suggesting that GAB1 is involved in response to multiple soluble factors. We have also identified another GAB1 function in the maintenance of &quot;tonic&quot; AKT phosphorylation via PI3K. Next, we demonstrated that transcription factor FoxO1 induces GAB1 by direct binding to its promotor. Altogether, increased FoxO1/GAB1 levels in CXCR4brightCD5dim CLL cells are contributing to balancing CLL cell survival and their decision to migrate into the immune niches. Notably, administration of ibrutinib therapy in CLL patients induces FoxO1-GAB1, which leads to recovery of phospho-AKT within several days-weeks on ibrutinib (Fig.C, n=11). This &quot;compensatory&quot; AKT activation allows CLL survival but can be therapeutically targeted by novel GAB1 inhibitors tested herein. GAB1 inhibitors can be used to induce apoptosis, inhibit CLL migration, basal AKT activity, and adaptive AKT activation during ibrutinib therapy. Conclusion: We described a novel FoxO1/GAB1-dependent regulatory mechanism of CLL homing and maintenance mechanism for &quot;tonic&quot; AKT signaling activity in an intraclonal CXCR4brightCD5dim CLL subpopulation (Fig.D). We showed for the first time that during ibrutinib therapy, CLL cells sustain AKT activity via the FoxO1-GAB1 axis and that this could be targeted by novel GAB1 inhibitors.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

—

OECD FORD branch

30205 - Hematology

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů