ADCC against MICA/B Is Mediated against Differentiated Oral and Pancreatic and Not Stem-Like/Poorly Differentiated Tumors by the NK Cells; Loss in Cancer Patients due to Down-Modulation of CD16 Receptor

Abstract

Tumor cells are known to upregulate major histocompatibility complex-class I chain related proteins A and B (MICA/B) expression under stress conditions or due to radiation exposure. However, it is not clear whether there are specific stages of cellular maturation in which these ligands are upregulated or whether the natural killer (NK) cells differentially target these tumors in direct cytotoxicity or antibody-dependent cell cytotoxicity (ADCC). We used freshly isolated primary and osteoclast (OCs)-expanded NK cells to determine the degree of direct cytotoxicity or of ADCC using anti-MICA/B monoclonal antibodies (mAbs) against oral stem-like/poorly-differentiated oral squamous cancer stem cells (OSCSCs) and Mia PaCa-2 (MP2) pancreatic tumors as well as their well-differentiated counterparts: namely, oral squamous carcinoma cells (OSCCs) and pancreatic PL12 tumors. By using phenotypic and functional analysis, we demonstrated that OSCSCs and MP2 tumors were primary targets of direct cytotoxicity by freshly isolated NK cells and not by ADCC mediated by anti-MICA/B mAbs, which was likely due to the lower surface expression of MICA/B. However, the inverse was seen when their MICA/B-expressing differentiated counterparts, OSCCs and PL12 tumors, were used in direct cytotoxicity and ADCC, in which there was lower direct cytotoxicity but higher ADCC mediated by the NK cells. Differentiation of the OSCSCs and MP2 tumors by NK cell-supernatants abolished the direct killing of these tumors by the NK cells while enhancing NK cell-mediated ADCC due to the increased expression of MICA/B on the surface of these tumors. We further report that both direct killing and ADCC against MICA/B expressing tumors were significantly diminished by cancer patients’ NK cells. Surprisingly, OC-expanded NK cells, unlike primary interleukin-2 (IL-2) activated NK cells, were found to kill OSCCs and PL12 tumors, and under these conditions, we did not observe significant ADCC using anti-MICA/B mAbs, even though the tumors expressed a higher surface expression of MICA/B. In addition, differentiated tumor cells also expressed higher levels of surface epidermal growth factor receptor (EGFR) and programmed death-ligand 1(PDL1) and were more susceptible to NK cell-mediated ADCC in the presence of anti-EGFR and anti-PDL1 mAbs compared to their stem-like/poorly differentiated counterparts. Overall, these results suggested the possibility of CD16 receptors mediating both direct cytotoxicity and ADCC, resulting in the competitive use of these receptors in either direct killing or ADCC, depending on the differentiation status of tumor cells and the stage of maturation and activation of NK cells.

Defective Patient NK Function Is Reversed by AJ2 Probiotic Bacteria or Addition of Allogeneic Healthy Monocytes

“…As previously described, NK cells play important roles in differentiating CSCs, leading to slower tumor growth, and decreased tumor metastasis [ 26 , 46 ]. Therefore, we cocultured autologous and allogeneic NK and monocytes and used their supernatants to differentiate OSCSCs.…”

“…Although the defect can be seen in most in-vitro treatments tested including those triggered by IL-2 or the combinations of IL-2 with anti-CD16 mAbs, or IL-2 with anti-CD3/28 mAbs or IL-2 with sAJ2 in PBMCs, the most significant defect was seen in those treated with IL-2 and anti-CD16 mAbs, and the least in those treated with IL-2 and sAJ2. Since we previously observed decreased expression of CD16 on patient NK cells [ 46 ] and significant differences in the function of PBMCs when they were activated with IL-2 and anti-CD16 mAbs, we undertook studies to understand the underlying mechanisms of the insufficient NK cell activation by anti-CD16 mAbs. We purified peripheral blood NK cells and studied their functions following cocultures with autologous and allogeneic monocytes obtained from cancer patient and those of the healthy individuals in the presence of IL-2 and anti-CD16 mAbs activation and compared the effect to those activated with IL-2 and sAJ2.…”

Defucosylation of Tumor-Specific Humanized Anti-MUC1 Monoclonal Antibody Enhances NK Cell-Mediated Anti-Tumor Cell Cytotoxicity

“…In addition, it has been suggested that CD16 down-regulation prevents NK cells from overactivation and exhaustion [ 57 ]. Still, lower baseline levels of CD16 correlate with decreased ADCC responses in NK cells: compared with NK cells obtained from healthy donors, it was demonstrated that NK cells from cancer patients showed a significant reduction of both direct killing and ADCC against tumors, which was due to CD16 down-regulation [ 58 ]. In cancer patients, the expression levels of CD16, DNAM-1, and NKG2D have also been reported down-regulation on NK cells [ 59 , 60 ].…”

Application of natural killer cells in pancreatic cancer (Review)

“…The clinical infusion of NK cells or its predecessors, lymphokine-activated killer cells, to treat metastatic tumors is a popular therapeutic direction (50,58,59). In a previous study, the NK-92 cell line was modified with a chimeric antigen receptor specific for PD-L1, ER-retained IL-2 and CD16 (60); in the study, preclinical data showed that these NK-92 cells could kill 15 tumor cell lines in vitro.…”