Clinical Significance Of CTCs In Gastric Cancer And The Influence Of EMT To Immune Escape In CTCs

Objective:To discuss relationship and clinical significance between positive tumor cells and clinical data on patients with gastric cancer;To further investigate the influence of EMT to immune escape in gastric circulating tumor cells.Methods:Peripheral blood samples from 41 patients with gastric cancer were collected and CTCs was used to identify by im-FISH method;The relationship between CTCs and clinical pathological data was analyzed by chi square test;RNA-ISH method was used to detect EMT markers and ULBP1 expression level in circulating tumor cells;The induction of gastric cancer cell line SGC-7901 induced by exogenous TGF-?1 was detected to EMT markers and NKG2DL expression levels using western blotting and immunofluorescence in the vitro experiment.Results:(1)Using the im-FISH method,CTCs was identified as:CEP8+(aneuploid)/CD45-/DAPI+ or/and CEP17+(aneuploid)/CD45-/DAPI+.(2)CTCs positive were found in 29 of the 41 patients with gastric cancer and the remaining 12 patients were found CTCs negative.The positive of CTCs was significantly correlated with tumor emboli existed in blood vessels of tumor(?2=5.448,P=0.034)and gastric cancer tumor marker CEA(?2=7.02,P=0.008),CA19-9(?2=5.11),P=0.038),CA72-4(?2=7.862,P=0.013),but CTCs were not significantly correlated with sex(?2=1.903,P=0.247),tumor staging(?2=0.029,P=0.595),differentiation(?2=0.620,P=0.505)and lymph node metastasis(?2=0.277,P=0.702).(3)The expression of ULBP1 in CTCs was negatively correlated with EMT.(4)Gastric cancer cell line SGC-7901 was induced EMT by TGF-?1,and the expression levels of NKG2DL(ULBP1/2 and MICA)were down-regulated in EMT gastric cancer cell lines..Conclusion:(1)CTCs are closely related to gastric cancer metastasis and clinical monitoring CTCs could help predict metastasis of gastric cancer;(2)It is obviously demonstrated that gastric CTCs in peripheral blood exhibited EMT characteristics,and presented down-regulation of NKG2D ligands;Induced-EMT by TGF-?1 accompanied by down-regulation of NKG2D ligands in vitro concluded that EMT of gastric CTCs might be involved in immune evasion of CTCs via shed or restrict expression of NKG2D ligands during process of metastasis.