Effect of cannabidiol on cytokine-induced killer cells in multiple myeloma and pancreatic cancer

Abstract

<em>Background/Aim:</em> Cytokine-induced killer cells (CIKs) are a heterogeneous population of polyclonal T lymphocytes showing a potent anti-tumor activity. Cannabinoids have been recently used for the treatment of cancer. In this study, CIK cells were tested for cannabinoid receptor CB2 expression and downstream signaling. They were also analyzed for neuropiilin (NRP) proteins expression which have been proven to play an important role in cancer. Moreover, we investigated whether inducing CIK cells with cannabidiol (CBD) can enhance their cytotoxicity primarily in pancreatic cancer and myeloma cells.<br /> <em>Materials and Methods:</em> CIK cells were analyzed by using flow cytometry and quantitative real-time polymerase chain reaction for CB2 and Neuropilins expression in distinct cell populations. Using multiple methods (flow cytometry, immunohistochemistry, laser cell microscopy, cytotoxicity based in vitro assays), we addressed the CBD modulation along with CIK cells. <br /> <em>Results:</em> Flow cytometry analysis revealed remarkable high levels of CB2 expression in distinct cell populations of CIK cells on days 7 and 14 of ex vivo expansion compared to peripheral blood mononuclear PBMC cells. IL-2 modulates primarily the expression of the CB2 receptor on CIK cells. CBD can have a protective role for CIK cells, but when used during ex vivo expansion of CIK cells inhibits the growth of the NKT population. Downstream signaling phosphop38 protein of CB2 was not detected in CIK cells, neither pancreatic cancer via flow cytometry. P-CREB was instead detected in CIK cells stimulated with pure cannabidiol, showing a difference within the different donors. Confocal microscopy experiments showed co-localization of p62 autophagosomal protein and CB2 receptors in CIK cells as well as pancreatic cancer cells. CIK cells were analyzed at different time points and the presence at low levels of NRP2, but not NRP1, was shown for CIK cells. CBD exerts an inhibition of CIK cytotoxic function against multiple myeloma (MM) and pancreatic cancer (PC) cells at high concentrations. <br /> <em>Conclusions:</em> A low dose of non-psychoactive CBD is sufficient to stimulate the cytotoxic function of CIK cells primarily in pancreatic and myeloma cells and may help to increase the therapeutic response. Recognizing NRP2 in CIK cells might help to improve CIK cell cytotoxicity.