Non-Coding RNAs Regulate Novel Signaling Pathways in AL Amyloidosis that are Targetable by BCL2/PI3K and MEK Inhibitors

Tal Zvida ^1,2 Eli Muchtar ³ Mali Salmon-Divon ^2,4 Angela Dispenzieri ³ Hila Fishov ^1,2 Claudio Schneider ⁵ Benjamin Bender ⁵ Adrian Duek ⁶ Merav Leiba ⁶ Ofer Shpilber ^2,4,7 Oshrat Hershkovitz-Rokah ^1,2

¹Department of Molecular Biology, Faculty of Natural Sciences, Ariel University, Israel
²Translational Research Lab, Assuta Medical Centers, Israel
³Department of Internal Medicine, Mayo Clinic, Division of Hematology, USA
⁴Adelson School of Medicine, Ariel University, Israel
⁵Orthopedic Department, Assuta Medical Centers, Israel
⁶Institute of Hematology, , Faculty of Health Science Ben-Gurion University of the Negev, Assuta Ashdod University Hospital, Israel
⁷Institute of Hematology, Assuta Medical Centers, Israel

AL-amyloidosis, clonal plasma cell disorder, is characterized by deposition of misfolded immunoglobulin light chain in vital organs, causing their dysfunction. Identifying novel therapeutic targets for AL-amyloidosis is essential since current treatments are limited and adapted from multiple myeloma (MM). We hypothesized that since AL and MM share similar molecular mechanism, we can identify novel therapeutic options for AL-amyloidosis, mediated by miRNA-mRNA interactions.

This study found miRNAs and mRNA differential expression in pre-treated bone marrow (BM) and plasma samples of AL compared with MM patients or healthy controls (HCs). Anti-apoptotic genes related to mitochondrial activity (BCL2, MCL1, BCL2L1) were upregulated in AL patients (n=50). Venetoclax, a BCL2 inhibitor, directly inhibits BCL2 and indirectly affect miRNAs that regulate these anti-apoptotic proteins. Furthermore, we identified a subset of miRNAs in AL patients that regulate PI3K and MAPK signaling pathways. Treatment with PI3K inhibitor (Idelalisib) and MEK inhibitor (Cobimetinib) resulted in downregulation of pAKT and pERK in ALMC-1 cells and inhibited cell proliferation. We also found that in 50 BM samples of newly diagnosed AL patients, AKT and ERK target genes were highly expressed. Treatment of ALMC-1 cells with PI3K /MAPK inhibitors led to their downregulation.

We revealed novel mechanisms, not related to DNA mutations, mediated by miRNAs in AL-amyloidosis. As BCL2 inhibitors are becoming an important therapy for AL-amyloidosis, this work lays the molecular foundation for this type of treatment. Other molecular mechanism such as PI3K and MAPK, may assist in tailoring more specific treatments.