Differential B-Cell Receptor Signaling Requirement for Adhesion of Mantle Cell Lymphoma Cells to Stromal Cells

Interactions between lymphoma cells and stromal cells play a key role in promoting tumor survival and development of drug resistance. We identified differences in key signaling pathways between the JeKo-1 and REC-1 mantle cell lymphoma (MCL) cell lines, displaying different patterns of stromal cell adhesion and chemotaxis towards stroma-conditioned medium. The identified adhesion-regulated genes reciprocated important aspects of microenvironment-mediated gene modulation in MCL patients. Five-hundred and ninety genes were differently regulated between the cell lines upon adhesion to stromal cells, while 32 genes were similarly regulated in both cell lines. Regulation of B-cell Receptor (BCR) signature genes in adherent cells was specific for JeKo-1. Inhibition of BCR using siRNA or clinically approved inhibitors, Ibrutinib and Acalabrutinib, decreased adhesion of JeKo-1, but not REC-1 cells. Cell surface levels of chemokine receptor CXCR4 were higher in JeKo-1, facilitating migration and adhesion of JeKo-1 but not REC-1 cells. Surface levels of ICAM1 adhesion protein differ for REC-1 and JeKo-1. While ICAM1 played a positive role in adherence of both cell lines to stromal cells, S1PR1 had an inhibitory effect. Our results provide a model framework for further investigation of mechanistic differences in patient-response to new pathway-specific drugs.

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Differential B-cell receptor signaling requirement for adhesion of mantle cell lymphoma cells to stromal cells

10.1101/2020.03.06.980235 ◽

2020 ◽

Author(s):

Laia Sadeghi ◽

Gustav Arvidsson ◽

Magali Merrien ◽

Agata M. Wasik ◽

André Görgens ◽

...

Keyword(s):

B Cell ◽

Mantle Cell Lymphoma ◽

Cell Lines ◽

Stromal Cells ◽

Cell Lymphoma ◽

Cell Receptor ◽

B Cell Receptor ◽

Model Framework ◽

Lymphoma Cells ◽

Mantle Cell

AbstractInteractions between lymphoma cells and stromal cells play a key role in promoting tumor survival and development of drug resistance. We identified differences in key signaling pathways between the JeKo-1 and REC-1 mantle cell lymphoma (MCL) cell lines, which exhibited different patterns of stromal cell adhesion and chemotactic migration towards stroma-conditioned medium. The identified adhesion-regulated genes reciprocated important aspects of microenvironment-mediated gene modulation in MCL patients. 590 genes were differently regulated between the cell lines upon adhesion to stromal cells, while 32 genes were similarly regulated in both cell lines. Regulation of B-cell Receptor (BCR) signature genes in adherent cells was specific for JeKo-1. Inhibition of BCR signaling by siRNA or clinically approved inhibitors, Ibrutinib and Acalabrutinib, decreased adhesion of JeKo-1 but not REC-1 cells to stromal cells. Cell surface levels of CXCR4 were higher in JeKo-1 cells and CXCR4 was important for migration and adhesion of JeKo-1 but not REC-1 cells. Surface levels of ICAM1 adhesion protein differ for REC-1 and JeKo-1. While ICAM1 plays a positive role in adherence of both cell lines to stromal cells, S1PR1 had an inhibitory effect. The results presented here provide a model framework for further investigation of mechanistic differences in patient-response to new pathway-specific drugs.

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Inhibition of B-cell receptor signaling disrupts cell adhesion in mantle cell lymphoma via RAC2

Blood Advances ◽

10.1182/bloodadvances.2020001665 ◽

2021 ◽

Vol 5 (1) ◽

pp. 185-197

Author(s):

Wenjun Wu ◽

Weige Wang ◽

Carrie A. Franzen ◽

Hui Guo ◽

Jimmy Lee ◽

...

Keyword(s):

Cell Adhesion ◽

B Cell ◽

Mantle Cell Lymphoma ◽

Cell Lines ◽

Cell Lymphoma ◽

Xenograft Model ◽

Cell Receptor ◽

B Cell Receptor ◽

Mantle Cell ◽

Bcr Signaling

Abstract Inhibition of the B-cell receptor (BCR) signaling pathway is highly effective in B-cell neoplasia through Bruton tyrosine kinase inhibition by ibrutinib. Ibrutinib also disrupts cell adhesion between a tumor and its microenvironment. However, it is largely unknown how BCR signaling is linked to cell adhesion. We observed that intrinsic sensitivities of mantle cell lymphoma (MCL) cell lines to ibrutinib correlated well with their cell adhesion phenotype. RNA-sequencing revealed that BCR and cell adhesion signatures were simultaneously downregulated by ibrutinib in the ibrutinib-sensitive, but not ibrutinib-resistant, cells. Among the differentially expressed genes, RAC2, part of the BCR signature and a known regulator of cell adhesion, was downregulated at both the RNA and protein levels by ibrutinib only in sensitive cells. RAC2 physically associated with B-cell linker protein (BLNK), a BCR adaptor molecule, uniquely in sensitive cells. RAC2 reduction using RNA interference and CRISPR impaired cell adhesion, whereas RAC2 overexpression reversed ibrutinib-induced cell adhesion impairment. In a xenograft mouse model, mice treated with ibrutinib exhibited slower tumor growth, with reduced RAC2 expression in tissue. Finally, RAC2 was expressed in ∼65% of human primary MCL tumors, and RAC2 suppression by ibrutinib resulted in cell adhesion impairment. These findings, made with cell lines, a xenograft model, and human primary lymphoma tumors, uncover a novel link between BCR signaling and cell adhesion. This study highlights the importance of RAC2 and cell adhesion in MCL pathogenesis and drug development.

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