Abstract 2845: The effective activation of highly purified NK cells expanded ex vivo on identified epithelial ovarian cancer cells.
Authors: Jin Young Mo , Lee Shin-Wha , Kim Yong-Man 
Published: August 2014

Objectives : Ovarian cancer is the 7th most common malignancy and the 5th most common cause of death from cancers in women. While many patients initially respond to surgery and chemotherapy, the long-term prognosis is generally unfavorable, with recurrence and development of drug-resistant disease. Therefore, new strategies of treatment, for examples, immunotherapy or targeted therapy, are necessary. This study evaluated the efficacy and safety of activated human natural killer (NK) cells against ovarian cancer.

Methods:Four Korean patients were selected from the Asan Medical Center. These patients were diagnosed with endometrioid adenocarcinoma (n = 2), papillary serous adenocarcinoma (n = 2). And two established human ovarian epithelial carcinoma cell lines (SKOV3 and OVCAR3) were used for all experiments. First of all, for the morphological analysis to detect ovarian cancer, cytokeratin (CK-7) was used on primary cells by fluorescence microscopy and nuclei were stained with DAPI. MTT assay to evaluate cell viability, the modified lactate dehydrogenase (LDH) release assay to determine the cytotoxic activity, and ELISA to detect the secretion levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and IL-12p70 were measured for the capacity of activated NK cells on the ovarian cancer cells.

Results: Primary cells were confirmed using CK-7 as a tool of distinction of ovarian cancers by fluorescence microscopy. Secondly, an MTT assay was performed to determine the effect of NK cells on the proliferation of cancer cells after 4, 12, 24, and 48 h of induction in cell ratios of 0.3:1, 1:1, and 3:1. NK cells caused the loss of cancer cell viability and proliferation, although the time courses and cell ratios differed by cancer cell type. Thirdly, to investigate whether NK cells could have a cytotoxic effect on cancer cells, an LDH assay was performed in NK cells and target cells. SKOV3 showed higher cytotoxicity than OVCAR3 in cancer cell lines and cytotoxicity of papillary serous adenocarcinoma cells was much more pronounced that all other cell types. Finally, IFN-γ and TNF-α were significantly released at all ratios in SKOV3 and OVCAR3 cell lines and patient-derived cells, but IL-12 secretion was not detected in all ovarian cancer cells. Although NK cells were activated independently from IL-12, these results suggest that various cytokines play a pivotal role in NK-cell-induced immune responses and could be evidence for activated NK cells.

Conclusion: Taken together, NK cells affect ovarian cancer cells upon treatment of direct killing malignant cells and producing cytokines that enhances both the innate and the antigen-specific anti-tumor response. Therefore, the results suggest that NK cell-based treatment could be an alternative immunotherapy for ovarian cancer patients.

Citation Format: Mo Jin Young, Shin-Wha Lee, Yong-Man Kim. The effective activation of highly purified NK cells expanded ex vivo on identified epithelial ovarian cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2845. doi:10.1158/1538-7445.AM2013-2845