IL1beta and soluble crosstalk modulate NF-κB activity in living Multiple Myeloma and stromal cells

ABSTRACT: Multiple myeloma (MM) progression is linked to chronic NF-κB activation in myeloma cells. However, the identity and source of autocrine/paracrine signals driving NF-κB activation and the role of the 3D microenvironment have been scarcely investigated both in vivo and in vitro. To investigate them, we knocked-in the Venus (YFP) ORF in the NF-κB p65 gene in both MM and stromal cells. Surprisingly, a large fraction of p65-YFP MM cells engrafted in mouse bone marrow showed overall low levels of NF-κB activation whereas a small fraction was highly activated. To understand these in vivo data, we investigated NF-κB dynamics in MM and stromal cells, both alone and in co-culture. In vitro experiments exploiting microfluidics, bioreactor and microchip cell cultures highlighted crosstalk between the myeloma and stromal components that leads to mild basal activation. In contrast, we found that high-density cultures within 3D scaffolds dampen NF-κB activation in MM and stromal cells, both in basal and inflammatory conditions. It has been recently hypothesized that IL1β, and the inflammatory ME, shape the overall activity of ME components and promote the transition of Mesenchimal Stromal Cells (MSCs) toward an inflammatory NF-κB driven transcriptional phenotype (iMSCs). We tested this hypothesis in our system and found that IL1β strongly activates NF-κB in stromal but not in myeloma cells. In addition, secreted molecules from IL1β-stimulated MSCs strongly activate NF-κB only in a small fraction of MM cells. We propose that the balance between activating stimuli from iMSCs and dampening feedbacks from the 3D ME, maintains a mild NF-κB activation in myeloma cells in the patients’ BM to avoid exceedingly harmful responses.

ORGANISM(S): Homo sapiens

PROVIDER: GSE197936 | GEO | 2024/11/05

REPOSITORIES: GEO