Increase of CIK cell efficacy by upregulating cell surface MICA and inhibition of NKG2D ligand shedding in multiple myeloma

Abstract

Multiple myeloma, which is a monoclonal plasma cell malignancy, still remains incurable despite recent progress in our understanding of this disorder. Adoptive immunotherapy of multiple myeloma using cytokine-induced killer cells is yielding promising results in clinical trials; however, some myeloma cells still evade immune surveillance by various unknown molecular mechanisms. This study aims at increasing the efficacy of cytokine-induced killer cells in targeting this tumor, using selective small-molecule inhibitors which increase and stabilize surface expression of the natural killer group 2, member D ligand, major histocompatibility complex class I polypeptide-related sequence A (MICA) on myeloma cells. We treated 2 multiple myeloma cell lines-U266 and KMS-12-PE-with 3 drugs. One of these drugs (sodium butyrate) is a histone deacetylase inhibitor. Another drug which was used (matrix metalloproteinase inhibitor III) blocks ligand shedding while the third drug (phenylarsine oxide) obstructs surface ligand internalization. The effect of these drugs on cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, surface ligand expression was examined using flow cytometry, and ligand shedding was assessed using enzyme-linked immunosorbent assay. We demonstrated that cytokine-induced killer cells have increased cytotoxicity against multiple myeloma cells after combined drug treatment than without drug pretreatment. We also established that this increased cytotoxicity was due to potent upregulation and stabilization of surface MICA on the surface of these tumor cell lines. Our study thus highlights further therapeutic options which could be used for the treatment of multiple myeloma patients.

CIK Cells and HDAC Inhibitors in Multiple Myeloma

“…For SB it has been established by flow cytometry that it leads to an up-regulation of MICA [21], whereas for the other two HDAC inhibitors such studies have yet to be conducted. In the recent past many NK cell activating substances relying on surface ligands have been approved for treatment of tumors.…”

Killers at the crossroads: The use of innate immune cells in adoptive cellular therapy of cancer

“…CIK cell lysis of tumors is mediated through NKG2D‐signaling and the engagement of MHC‐related ligands MICA/B and the ULBP family of ligands, the expression of which is frequently upregulated in hematologic or solid cancers (Figure 1B). 59‐61 Several protocols for the generation of CIK cells have been reported, and typically involve the sequential incubation of peripheral blood lymphocytes with interferon (IFN)‐γ, anti‐CD3 mAb, and IL‐2 62 . The use of IL‐15 in the presence or absence of IL‐2 has also been shown to induce faster expansion of CIK cells to exhibit enhanced cytotoxicity, with the additional advantage of inducing fewer numbers of suppressive Treg cells 63,64 .…”

Anticancer potential of naturally occurring immunoepigenetic modulators: A promising avenue?

“…47 MICA overexpression and stabilization on the surface of U266 and KMS-12-PE myeloma cells treated with butyrate, in combination with a matrix metalloproteinase inhibitor III and phenylarsine oxide (to block ligand shedding and obstruct surface ligand internalization, respectively), led to increased cytotoxicity of peripheral blood mononuclear cell-derived, cytokine-induced killer cells against myeloma cells. 48 It is noteworthy that butyrate-induced MICA overexpression could be used to overcome impaired NK cell recognition and tumor immune evasion provoked by the treatment of metastatic melanoma cells by the specific BRAFV600E (proto-oncogene B-Raf valineto-glutamate substitution at codon 600) mutant inhibitor vemurafenib, which strongly decreases the surface expression of MICA and CD155. 49 Additional studies suggest that butyrate could be used in the context of cancer immunotherapy by suppressing immunotolerance.…”