Effect of vasoactive intestinal peptide (VIP) on NKG2D signal pathway and its contribution to immune escape of MKN45 cells.
OBJECTIVE
To investigate VIP effect on the cytotoxicity of NK cell to gastric cancer cells in vitro and the relation between the effect with the NKG2D signal molecules in NK cells.


METHODS
NK cells were purified from peripheral blood mononuclear cells (PBMC). Before and after NK cells were incubated with VIP or its antagonist (D-p-Cl-Phe6,Leu17)-VIP, we detected the cytotoxicity of NK cells to MKN45 gastric cancer cells by MTT and detected the expressions of NKG2D, DAP10, and NF- κ B proteins and mRNAs in NK cells by immunocytochemistry and RT-PCR in those conditions. Then we analyzed the effect of VIP and its antagonist on the cytotocicity of NK cell to gastric cancer cells and on expressions of NKG2D, DAP10, and NF- κ B signal molecules in NK cells.


RESULTS
VIP could inhibit the cytotoxicity of NK cells to MKN45 cells and could inhibit the expressions of NKG2D, DAP10, and NF- κ B in NK cells. However, (D-p-Cl-Phe6, Leu17)-VIP could reverse those effects.


CONCLUSIONS
The VIP inhibited the cytotoxicity of NK cell to MKN45 cells which might get through inhibiting the expressions of NKG2D signal molecules in NK cells. This may be one mechanism of gastric cancer cells escaping organism immune clearance.
Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China.
Chong
C
Wang
Xi-Jin
XJ
Zhou
Yuan-Yuan
YY
Li
Juan
J
Wan
Le-Ying
LY
Yang
Guo-Hua
GH
Li
D000704:Analysis of Variance; D045744:Cell Line, Tumor; D003601:Cytotoxicity Tests, Immunologic; D017931:DNA Primers; D006801:Humans; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000276:immunology*; D016328:NF-kappa B / Q000378:metabolism; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D018709:Statistics, Nonparametric; D013778:Tetrazolium Salts; D013844:Thiazoles; D019139:Tumor Escape / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D017931:DNA Primers; C120528:HCST protein, human; C527085:KLRK1 protein, human; D016328:NF-kappa B; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic; D013778:Tetrazolium Salts; D013844:Thiazoles; D014660:Vasoactive Intestinal Peptide; C022616:thiazolyl blue