Supercharged NK cells, unlike primary activated NK cells, effectively target ovarian cancer cells irrespective of MHC-class I expression.

Abstract

Objective: To demonstrate the significance of supercharged natural killer (sNK) cells to target aggressive gynecological tumours.

Methods and analysis: We used cell cultures of peripheral blood-derived mononuclear cells (PBMCs) and purified NK cells alone and in the presence of tumours. MHC-class gene expression assessments of ovarian tumours were performed using gene set enrichment analysis (GSEA). Secretion and expression levels of cytokines in PBMCs and NK cells were determined using ELISA and scRNA seq analysis, respectively. A flow cytometer was used for surface marker analysis. ⁵¹Cr and eSight were used to determine the killing activity of NK cells.

Results: We have observed a significant decrease in the numbers and functions of NK cells in patients with ovarian cancer. GSEA revealed differently expressed genes, decreased differentiation- and immune-related genes, and increased genes for cell cycle analysis in recurrent tumours compared with chemo-naive ovarian tumours. Increased gene expression as well as secretion of interferon-γ and tumour necrosis factor-α and increased avidity in binding to tumour cells by sNK cells was observed. Unlike primary interleukin (IL)-2-activated NK cells, sNK cells effectively lysed OVCAR8 ovarian poorly differentiated cancer stem-like cells (PDCSCs) and well-differentiated OVCAR4 tumours. Primary ovarian tumours with lower MHC-class I expression were highly susceptible to both primary IL-2-activated NK and sNK cells, whereas the well-differentiated tumours with high expression of MHC-class I were only susceptible to sNK cells.

Conclusion: The use of sNK cells in immunotherapy emerges as a potentially effective strategy to target and eliminate the majority of ovarian tumour clones, thereby providing a potential therapeutic opportunity in preventing the recurrence of the disease.