Aim
Natural-killer group 2, member D (NKG2D) is an activating receptor on natural killer cells and activated T-cells, designated cytokine-activated killer (CAK) cells here. The MHC class I chain-related A and B (MICA and MICB, respectively) are ligands of NKG2D and are expressed on various human tumor cells, including hepatocellular carcinoma (HCC) cells. Here, we investigate whether gemcitabine, a chemotherapeutic agent, affects MICA/B expression in HCC. Materials and
Conclusion
Gemcitabine induced MICA/B expression in HepG2 cells, resulting in synergistic enhancement of the cytotoxic effects of NKG2D-high CAK cells. The combination of gemcitabine and CAK cells may have clinical therapeutic significance for HCC.
Methods
We used ELISA, RT-PCR and adherent target detachment assays to determine expression of MICA/B in HepG2 HCC cells and the level of cellular cytotoxicity generated by treatment with gemcitabine and/or CAK cells.
Results
Surface expression of MICA/B was evident after gemcitabine treatment, and MICB-specific mRNA was up-regulated. Pre-treatment with gemcitabine and subsequent exposure to CAK cells induced greater cytotoxicity than either treatment alone. Inclusion of soluble MICB significantly reduced cytotoxicity.