[Expression and significance of NKG2D ligands in 13 tumor cell lines]
Yi-Ping Wang1, Cai Zhang, Jia-Feng Niu
1Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, Shandong, 250062, P. R. China.
Background & Objective:
The interaction between NKG2D and its ligands plays a major role in immune surveillance against tumor. This study was to observe the expression and analyze the significance of NKG2D ligands in 13 tumor cell lines.
Methods:
The mRNA expression of NKG2D ligands in K562, Raji, PG, Hep2, HepG2, HeLa, HT29, M21, MDA231, SGC7901, Caski, HL-60 and Jurkat cells was measured by reverse transcription-polymerase chain reaction (RT-PCR). The cytotoxicity of natural killer (NK) cells to the tumor cells at different effector-to-target cell (E:T) ratios were detected by MTT assay. The expression of MICA protein was measured by SABC immunohistochemistry and Western blot.
Results:
The 13 tumor cell lines expressed different levels of NKG2D ligands. MICA was highly expressed in Hep2 cells, but not expressed in Caski, PG, HL-60 and Raji cells. The expression of MICA and MICB were positively correlated to the cytotoxicity of NK cells (r=0.851, P<0.001; r=0.652, P<0.05). Except for ULBP3, the expression of ULBP1, 2, 4 had no correlations to the cytotoxicity of NK cells.
Conclusion:
Among the 6 human NKG2D ligands, the expression of MICA is most intimate to the cytotoxicity of NK cells to tumor cells, and its expression level may determine the degree of immune response of NK cells to tumor.
