RFP Reporter Cell Line - PC3

Dark cumin, or Nigella sativa, is a widely recognized and highly popular medicinal herb frequently used to treat gastrointestinal disorders, diabetes, bronchitis, hypertension, and cancer. The anticancer efficacy of Nigella sativa may be attributed to its immunomodulatory effects, specifically its ability to activate the body's natural killer (NK) cells. As a subset of lymphocytes, NK cells constitute a vital component of the innate immune system, serving as the body's first line of defense against infections. To explore potential avenues for optimizing immunotherapy using natural products, researchers investigated the regulatory effects of thymoquinone (TQ)-a key active constituent of Nigella sativa-on NK cell activity by assessing its impact on NK cell cytotoxicity and the release of associated biochemicals. The results demonstrated that, following the addition of TQ, the cytotoxic activity of NK cells against PC3-RFP cells was significantly enhanced, with the killing rate increasing from 55.1% to 85.35%. Furthermore, in the presence of 50 µM TQ, the secretion levels of both perforin and granzyme B by NK cells were significantly higher than those observed in the control group. Moreover, at TQ concentrations of both 25 µM and 50 µM, the levels of interferon-α (IFN-α) produced by NK cells were also significantly elevated compared to the control group. In summary, TQ enhances the cytotoxicity of NK cells against PC3-RFP cells, thereby suggesting its potential utility in the development of cell-based immunotherapies.

The cytotoxicity of NK cells was evaluated through co-culture with red fluorescent protein-expressing PC3 cells (PC3-RFP cells). Specifically, the effector-to-target cell ratio (NK cells to PC3-RFP cells) was set at 1:2, and varying concentrations of TQ (25 µM and 50 µM) were added to the culture medium. The results demonstrated that the cytotoxicity of NK cells was significantly enhanced in the presence of TQ: both concentrations of TQ significantly upregulated NK cell-mediated cytotoxicity against PC3-RFP cells, reaching a cytotoxicity level of 85.35%, whereas the cytotoxicity of the control group-NK cells co-cultured solely with tumor cells-was only 55.1%. Furthermore, in the presence of NK cells, the cytotoxicity observed in tumor cells treated with 25 µM and 50 µM TQ was significantly higher than that observed in tumor cells treated with equivalent concentrations of TQ in the absence of NK cells (Figure 1).

Figure 1. NK cell cytotoxicity against PC3-RFP cells in the presence or absence of TQ. (Aldarmahi N A, et al., 2025)