Abstract 3811: Micro-RNA induced inactivation of inflammatory cytokine signaling pathways in Waldenstrom macroglobulinemia compared to IgM-MGUS
Authors: Chohan Karan , Paludo Jonas , Dasari Surendra , Abeykoon Jithma P. , Kapoor Prashant , Braggio Esteban , Manske Michelle K. , Paulus Aneel , Reeder Craig B. , Ailawadhi Sikander , Chanan-Khan Asher A. , Kyle Robert A. , Gertz Morie A. , Novak Anne J. , Ansell Stephen M. 
Published: June 2023

Abstract
Introduction: Cytokines are protein factors that regulate diverse cellular processes. The malignant progression of immunoglobulin M monoclonal gammopathy of undetermined significance (IgM-MGUS) to Waldenstrom macroglobulinemia (WM) is in part cytokine mediated, and we have previously shown IL-6 mediates IgM secretion in WM via the JAK/STAT pathway. Cytokine signaling can be epigenetically modulated by micro-RNAs (miRs). We aimed to identify the role of miRs in the regulation of inflammatory cytokine pathways between these diseases.
Methods: Bone marrow samples of patients with IgM-MGUS (n=7) and WM (n=25) were prospectively collected and sorted for CD19+ and/or CD138+ malignant cells. Total RNA extraction and sequencing were performed, miR and mRNA profiling was conducted, and differential expression was calculated between WM and IgM-MGUS using a log2 fold change (FC)&gt;0.5 and ←0.5, false discovery rate&lt;0.05. Experimental differentially expressed miR-mRNA pairing was performed, and pairs were filtered for correlated expression (i.e., upregulated miR/downregulated mRNA, and vice-versa). Filtered pairs were analyzed using the Ingenuity Pathway Analysis to identify pathways between WM and IgM-MGUS with absolute activation Z-score ≥1.
Results: We identified 34 differentially expressed miRs experimentally targeting 1132 mRNAs. Pathway analysis showed overall miR-based inactivation of inflammatory cytokine signaling pathways in WM compared to IgM-MGUS, especially of the interleukin (IL) family: IL-2, IL-6, IL-8, IL-9, IL-15, and IL-17. Underlying multiple pathways was upregulation of miRs-146a, 150, 194, all targets of Signal Transducer and Activator of Transcription 1 (STAT1), observed to be downregulated. Of relevance, miR-146a has been previously shown to be an inhibitor of inflammatory cytokines, including IL-6. Next, we observed upregulation of miR-142 which targets phosphoinositide-3-kinase regulatory subunit 6 (PIK3R6), observed to be downregulated. Both the STAT and PIK3 families are important cytokine signal transducers, and we have previously shown the PI3k-AKT-IkB-p65 pathway induces expression of IL-6 via a GLI2-mediated mechanism. We additionally observed granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling to be inactivated in WM. Here, miR-19b and miR-30e were upregulated, both target CSF 2 receptor subunit beta (CSF2RB), found to be downregulated. CSF2RB is the common receptor subunit of GM-CSF, IL-3, and IL-5.
Conclusion: Our study identifies multiple cytokines pathways involved in inflammation and the tumor microenvironment to be potentially inactivated by differentially expressed miRs in WM compared to IgM-MGUS. Downregulation of these pathways and targeting of the STAT and PIK3 family indicates a possible miR-based negative feedback loop to down-modulate inflammatory cytokine signaling in WM.
Citation Format: Karan Chohan, Jonas Paludo, Surendra Dasari, Jithma P. Abeykoon, Prashant Kapoor, Esteban Braggio, Michelle K. Manske, Aneel Paulus, Craig B. Reeder, Sikander Ailawadhi, Asher A. Chanan-Khan, Robert A. Kyle, Morie A. Gertz, Anne J. Novak, Stephen M. Ansell. Micro-RNA induced inactivation of inflammatory cytokine signaling pathways in Waldenstrom macroglobulinemia compared to IgM-MGUS. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3811.