Abstract:

Objective To investigate the role of CD4⁺CD25^highCD127^low regulatory T cells（Treg） in the metastasis of epithelial ovarian cancer（EOC）,and to analyze the signaling mechanism of the related cytokines. Methods Flow cytometry was used to determine the percentages of CD4⁺CD25^highCD127^low Treg in peripheral blood of 34 patients with EOC,26 patients with benign ovarian tumors and 34 healthy subjects（healthy control group）. The clinical data of all patients,including age,pathological type,the International Federation of Gynecology and Obstetrics（FIGO） stage,histological differentiation and lymph node metastasis,were collected. A coculture system between EOC cell line OVCAR3 and healthy subjects' CD4⁺ T cells was established. The levels of interleukin 10（IL-10） and transforming growth factor-beta 1（TGF-β1） were determined by enzyme-linked immunosorbent assay（ELISA）. The expression levels of matrix metalloproteinase（MMP）-2 mRNA and tissue inhibitor of metalloproteinase（TIMP）-2 mRNA in OVCAR3 were determined by real-time fluorescence quantitation polymerase chain reaction（PCR）. The levels of MMP-2 mRNA and TIMP-2 mRNA were also analyzed after blocking IL-10 receptor and TGF-β1 receptor in OVCAR3 after the coculture experiment. Results The level of CD4⁺CD25^highCD127^low Treg in EOC group was higher than those in benign ovarian tumor and healthy control groups（P<0.05）,and there was no statistical significance between benign ovarian tumor and healthy control groups（P>0.05）. The percentage of CD4⁺CD25^highCD127^low Treg was higher in lymphatic invasion group than that in non-lymphatic invasion group（P<0.05）. There was no statistical significance for CD4⁺CD25^highCD127^low Treg percentage in EOC group with different ages,pathological types,FIGO stages and histological differentiation（P>0.05）. The levels of IL-10 and TGF-β1 from CD4⁺ T cells were up-regulated after coculturing with CD4⁺ T cells（P<0.05）. The level of MMP-2 mRNA was up-regulated（P<0.05）,and the level of TIMP-2 mRNA in OVCAR3 was down-regulated in the coculture experiment with CD4⁺ T cells（P<0.05）. The level of MMP-2 mRNA was down-regulated,and the level of TIMP-2 mRNA in OVCAR3 was up-regulated after blocking（P<0.05）. Conclusions CD4⁺CD25^highCD127^low Treg can enhance the expression of IL-10 and TGF-β1 and stimulate the related receptors on EOC cells. It plays a role in the invasion and metastasis of EOC.

Key words: Regulatory T cell, Matrix metalloproteinase 2, Tissue inhibitor of metalloproteinase 2, Epithelial ovarian cancer