Phenotypic and Functional Characteristics of Blood Natural Killer Cells from Melanoma Patients at Different Clinical Stages

Abstract

Melanomas are aggressive skin tumors characterized by high metastatic potential. Immunotherapy is a valuable alternative for metastatic melanoma patients resistant to chemotherapy. Natural Killer (NK) cells are efficient anti-tumor cytotoxic effectors. We previously showed that blood NK cells from stage IV metastatic melanoma patients display decreased NK receptors and that chemotherapy modifies the functional status of blood NK cells. To investigate the role of NK cells along melanoma progression, we have here studied NK cells from patients at different stages of the disease. First, we showed that ex vivo NK cells from certain stage III–IV patients displayed low degranulation potential. Using a dynamic label-free assay, we found that immunoselected IL-2 activated blood NK cells from patients efficiently lysed melanoma cells through NKp46 and NKG2D receptors, independently to the clinical stage. Moreover, the ex vivo phenotype of circulating NK cells from 33 patients (stage I to IV) was extensively analyzed. NK cells from patients displayed higher variability in the percentages of Natural Cytotoxicity Receptors (NCR) and Natural Killer Group 2D (NKG2D) receptor expression compared to donor NK cells. The main defect was the decreased expression of NCR1 (NKp46) by NK cells from metastatic patients. Interestingly, we found a positive correlation between the NK cell percentages of NKp46 and the duration of stage IV in melanoma patients. Finally, we showed that NK cells infiltrated primary melanomas and displayed a predominant peritumoral distribution. These results are new arguments for the development of NK-based therapies in melanoma patients.

NKp30 isoforms and NKp46 transcripts in metastatic melanoma patients: Unique NKp30 pattern in rare melanoma patients with favorable evolution

“…4C right panel). These data are in accordance with our previous work describing a correlation between NKp46 expression and duration of stage IV in metastatic patients 15 indicating the importance of NKp46 in melanoma evolution.…”

“…These results confirmed and further strengthened our previous data showing an impact of NKp46 expression at the surface of blood NK cells on the duration of stage IV in melanoma patients. 15 Interestingly, our data show that NKp30A expression level isoform (NK cell fitness) was elevated in rare LS patients that have controlled a metastatic disease. These LS are characterized by unique polymorphisms and isoforms proportions of NKp30.…”

“…23 In blood NK cells, we observed a progressive decrease of NKp46 expression level in patients with advanced melanoma and this alteration correlated with shorter duration of stage IV. 15 In addition, chemotherapy treated patients displayed distinct phenotypic modulations, 24 indicating that tumor progression and conventional chemotherapy may interfere with NK cell status in melanoma patients. 25 In a recent study, comparing tumor positive and tumor-free Sentinel lymph nodes (SLN), we found that more numerous cytotoxic cells (CD8 C cells, Granzyme C cells, NK cells) infiltrated tumor-free SLN.…”

NKp30 isoforms and NKp30 ligands are predictive biomarkers of response to imatinib mesylate in metastatic GIST patients

“…In nearly all the reports, NK cells were underrepresented in the inflammatory infiltrates, 24 except in colorectal carcinoma 25 and in GIST 11 where they mostly resided in the peri-tumoral areas. 11,26,27 NK cell functions were also seen to be repressed in tumor beds in breast and lung malignancies, due to a downregulation of their natural cytotoxic receptors. 26,28,29 Hence, in most malignancies, NK cell abundance in TILs fails to correlate with clinical outcome.…”

Intratumoral natural killer cells show reduced effector and cytolytic properties and control the differentiation of effector Th1 cells

“…Previous studies have shown no differences in NKG2D expression between peripheral blood mononuclear cells (PBMCs) and LN NK cells in melanoma patients and healthy individuals. [33][34][35][36] However, these studies did not examine the NKG2D expression in tumor infiltrating NK cells. We observed significantly lower NKG2D expression in the intratumoral NK cells, but no difference in the splenic population, between naive and tumorbearing mice.…”