The Relation Between HLA-G And Human Ovarian Carcinoma

Objective: human leukocyte antigen-G (HLA-G) is a nonclassical human leukocyte classⅠb antigen (HLA-Ⅰ), which was first observed to be expressed by the placenta on the extravillous cytotrophoblast . And its effect on the fetal-maternal immune tolerance has been confirmed. During the last few years, the HLA-G field has evolved from being a topic restricted to reproduction to a very broad topic that spans from transplantation to autoimmunity and oncology. The HLA-G and immune escape of tumor has become focal point in the oncology field.Human ovarian carcinoma is frequent in gynecological malignant tumor. At present, exterminating tumor cells of ovarian carcinoma and union chemotherapy are the main therapy methods for human ovarian carcinoma. It is difficult to search out at early stage and to cure thoroughly by the operation. And it is easy to recur after operation. The patient who can live for five yeas is rare. So explore the utility drug for human ovarian carcinoma is the key to elevate the life span of the patient. The aim of this study was to investigate the correlation of HLA-G to immune escape of human ovarian carcinoma and to explore drug which can down regulate the expression of HLA-G.Methods:1 RT-PCR method and flow cytometry was performed to examine the expression of HLA-G mRNA and protein in 50 human ovarian carcinoma and 30 benign tumor of the ovary and 10 normal ovarian tissues.2 Human ovarian carcinoma OVCAR3 cells were cultured in vitro. The models of xenografted tumor were established by the transplantation of human ovarian carcinoma OVCAR3 cell on the nude mice.3 The 28 nude mice were randomly divided in to four groups when the xenografted tumor grows two weeks and then the circumscription of tumor was distinct. They were control group, DDP group, mifepristone(MIF)group and DDP+ MIF group.4 Pay attention to food and drink,activity and response of the nude mice in the lab process. The tumor volumes of the mice were measured respectively during the therapy time. The curves of tumor growth were draw. Moreover, the tumor growth inhibiting rates of each group were calculated.5 RT-PCR method and flow cytometry was performed to examine the expression of HLA-G mRNA and protein in the xenografted tumor of nude mice in different groups.Results:1 The expression of HLA-G mRNA in 50 human ovarian carcinoma and 30 benign tumor of the ovary and 10 normal ovarian tissues detected by RT-PCR:the positive expression rate of HLA-G mRNA was 92.00%, 66.67% and 60.00% in ovarian carcinoma group, benign tumor group and normal ovarian tissues group respectively. It was higher in ovarian carcinoma group than in benign tumor and normal ovarian tissues group(sp<0.05, p<0.05 respectively).The positive expression rate of HLA-G mRNA in different types of ovarian carcinoma has no significant difference (p>0.05). It was 76.92% and 97.30% in earlier period and advanced period respectively. It has no significant difference between them(p>0.05).The positive expression rate of HLA-G mRNA in well differentiated group,moderately differentiated group and poorly differentiated group was 62.50%, 96.30% and 100.00% respectively. It was lower in well differentiated group than in moderately differentiated and poorly differentiated groups(p<0.05, p<0.05 respectively).2 The expression of HLA-G protein in 50 human ovarian carcinoma , 30 benign tumor of the ovary and 10 normal ovarian tissues detected by flow cytometry: the positive expression rate of HLA-G protein was 64.00%, 16.67% and 10.00% in ovarian carcinoma group, benign tumor group and normal ovarian tissues group respectively. It was significantly higher in ovarian carcinoma than in benign tumor and normal ovarian tissues group(sp<0.01, p<0.01 respectively). The positive expression rate of HLA-G protein in different types of ovarian carcinoma has no significant difference (p>0.05). It was 30.77% and 75.68% in earlier period and advanced period ovarian carcinoma respectively. The difference was statistically significant(p<0.05). The positive expression rate of HLA-G protein in well differentiated group,moderately differentiated group and poorly differentiated group was 37.50%, 55.56% and 93.71% respectively. It was higher in poorly differentiated group than in well differentiated and moderately differentiated groups(p<0.05, p<0.05 respectively).3 Comparison the tumor volumes of nude mice between different groups: the tumor volumes were 6100.83±600.69 mm3, 3491.40±320.13 mm3, 3689.30±417.66 mm3, 2532.55±252.56 mm3 in control group, DDP group, MIF group and DDP+ MIF group respectively. The inhibition rates of the tumors were 0.00%, 42.77%, 39.53%, 58.49%. The tumor volumes of control group were significantly larger than other three groups(p<0.01 all). DDP group and MIF group were significantly different compared with DDP+ MIF group ( p < 0.01, p < 0.01 respectively).4 The expression of HLA-G mRNA in the xenograft of nude mice of human ovarian carcinoma OVCAR3 cell detected by RT-PCR: it was 1.01±0.17, 0.89±0.11, 0.62±0.10, 0.49±0.10 in control group, DDP group, MIF group and DDP+ MIF group respectively. There was no significant difference between DDP group and the control group(p>0.05); It was lower in MIF group than in control group(p<0.01). There was no significant difference between MIF group and DDP+ MIF group(p>0.05).5 The expression of HLA-G protein in the xenograft of nude mice of human ovarian carcinoma OVCAR3 cell detected by flow cytometry : it was 2.38±0.43, 2.29±0.35, 1.26±0.31, 1.08±0.25 in control group, DDP group, MIF group and DDP+ MIF group respectively. There was no significant difference between DDP group and control group(p>0.05). It was lower in MIF group than in control group(p<0.01). There was no significant difference between MIF group and DDP+ MIF group(p>0.05).Conclusions:1 The positive expression rate of HLA-G antigen in malignant tumor group was higher than in benign tumor and normal ovarian tissues groups. The positive expression rate of HLA-G antigen was associated with the clinical stage and differentiated extent. It suggested that HLA-G was related with the development of human ovarian carcinoma and might contributed to the immune escape of tumor cells. HLA-G could be treated as a reference index for judging prognosis and provide grounds for the immunotherapy of human ovarian carcinoma.2 MIF could inhibit the growing of the xenograft of nude mice of human ovarian carcinoma OVCAR3 cell. The result suggested that MIF has the antineoplasmic activity. The effect became more powerful when MIF added with DDP.3 MIF could down regulate the expression of HLA-G of the xenograft tissues of nude mice. It suggested that MIF could relive the inhibiting of activated immune cells by down regulating the expression of HLA-G. Then recovered the killing effect to tumor cells and inhibited the growing of tumor. This might be the one of the mechanisms that MIF educe the effect of anti-cancer. The effect and mechanism of MIF would provide the grounds for the therapy of human ovarian carcinoma especially the patient who expressed HLA-G highly.