(PA-302) Role and Mechanism of Pim-2 Kinase Inhibitors-induced Immunogenic Cell Death in Multiple Myeloma

Immune dysfunction is an important part of pathogenesis in multiple myeloma, and restoring anti-myeloma immunity has become a key research direction. The goal of this study was to determine whether and how Pim-2 kinases inhibitors induce immunogenic cell death in multiple myeloma.

Methods:

By using bioinformatics, reanalyze scRNA seq data from the Gene Expression Omnibus (GEO) database to explore the expression of Pim-2 gene, endoplasmic reticulum stress, and DAMP related genes in MM patients.In vitro, SMI-16a were applied to MM cell lines (RPMI-8226, OPM-2, U266) for 24 hours, followed by DCFH-DA staining. Flow cytometry (FCM) was used to detect intracellular reactive oxygen species (ROS) levels and the expression of Calreticulin (CALR) on the surface of MM cells. Western blot (WB) was used to detect the expression of DAMPs (HMGB1, HSP70) in the supernatant.Co-culture DCs, pan-T lymphocytes,NK cells and MM cell lines treated with PBS, SMI-16a, IL-15 superagonist fusion protein, and SMI-16a+ IL-15 superagonist fusion protein.

Results:

Pim-2 kinase inhibitors up-regulate IRE1 phosphorylation, promote XBP1 and CHOP transcription,thereby mediating endoplasmic reticulum stress in MM cells.ER-stress and increased ROS levels can promote the expression of damage related molecular patterns and promote immunogenic cell death in MM cells.Pim-2 kinase inhibitors-treated MM cell lines can up-regulate the expression of activation molecules on the surface of DCs from MM patients, promote T lymphocyte differentiation from Naïve T cells to effector memory T cells, and promote the expression of T lymphocyte functional molecules. In addition, combination of IL-15 superagonist fusion protein and SMI-16a can improve the expression of CD107a, NKG2D, Granzyme B and perforin in NK cells.

Conclusions:

Pim-2 kinases regulates anti-myeloma immunity and provide efficient therapy for applying Pim-2 kinases inhibitors in MM treatment.