Coffee Diterpenes Potentiate the Cytolytic Activity of KHYG-1 NK Leukemia Cells

Natural killer (NK) cells play a critical role in early host defense against tumor and virus-infected cells. Here, we report that two coffee diterpenes, cafestol and kahweol, potentiate the cytotoxic activity of KHYG-1, an NK leukemia cell line, against the NK-sensitive cell line K562. Western blot analysis and quantitative real-time PCR indicated that cafestol and kahweol markedly enhanced the expression of granzyme B. While both diterpenes had no or little effect on the expression of other cytotoxic effector molecules, kahweol elevated the phosphorylated forms of ATF-2, c-Jun and CREB transcription factors, which might participate in granzyme B gene expression. These results suggested that cafestol and kahweol upregulate granzyme B expression by activating transcription factors, leading to enhanced cytolytic activity of NK cells.