Abstract:

Objective To explore the role of chemokine CX3CL1/CX3CR1 in intraperitoneal metastasis of ovarian cancer in nude mice. Methods Fifty SPF SD female nude mice were selected and randomly divided into normal group （n=10）， ovarian cancer model group （n=20） and CX3CL1 group （n=20） by random number table method. Ovarian cancer model was not established in normal group， and ovarian cancer model was established in both ovarian cancer model group and CX3CL1 group. CX3CL1 group was given intraperitoneal injection of 20 μl CX3CL1 with a concentration of 10 ng/μl to observe the survival status of nude mice. Tumor mass， tumor volume， tumor inhibition rate， ascites rate and peritoneal metastasis rate were recorded. The pathological morphology of ovarian tissue was examined by HE staining， the expression of CX3CL1/CX3CR1 in ovarian tissue was detected by Western blotting， and the correlation between the expression of CX3CL1/CX3CR1 and peritoneal metastasis rate was analyzed by point two-column correlation. Results During the administration， the mental state， activity， food and water intake of nude mice in the normal group were good with sensitive responses. The nude mice in the ovarian cancer model group showed signs of mental fatigue， reduced activity， less food and water intake， delayed response， as well as and a hard and gradually enlarged abdomen. The mental state， activity， food and water intake of nude mice in CX3CL1 group were better than those in ovarian cancer model group， and the abdominal hardness volume was smaller compared with that in ovarian cancer model group. The survival time of normal group， ovarian cancer model group and CX3CL1 group were （14.00±0.00）， （9.24±0.67） and （12.05±0.82） d， respectively， with a statistically significant difference （F=22.27， P<0.001）. Further pair-to-pair comparisons showed that the normal group had the longest survival time， followed by the CX3CL1 group and the ovarian cancer model group （all P<0.05）. The tumor mass of ovarian cancer model group and CX3CL1 group was （1.31±0.21） and （0.62±0.13） g， respectively， with a statistically significant difference （t=12.49， P<0.001）. The tumor volumes were （130.47±13.45） and （70.02±7.52） mm³， respectively， with a statistically significant difference （t=17.54， P<0.001）. The tumor suppression rates were （0.00±0.00）% and （48.96±4.74）%， respectively， with a statistically significant difference （t=46.19， P<0.001）， the ascites rates were 60.00% （12/20） and 25.00% （5/20）， respectively， with a statistically significant difference （χ²=5.01， P=0.025）. The abdominal metastasis rates were 80.00% （16/20） and 50.00% （10/20）， respectively， with a statistically significant difference （χ²=3.96， P=0.047）. The results of HE staining showed that in the normal group， the ovarian tissue structure was complete， the follicles and oocytes developed normally with good shape， and no cancerous cells were found. The ovarian structure of the ovarian cancer model group was obviously destroyed， and a large number of cancerous cells could be seen. The nucleolus were deeply stained and the number increased. Compared with the ovarian cancer model group， the pathological structure was significantly improved， and the number of cancer cells was significantly decreased in the CX3CL1 group. The CX3CL1 protein relative expression levels in normal group， ovarian cancer model group and CX3CL1 group were 2.05±0.22， 1.33±0.11 and 2.41±0.24， respectively， with a statistically significant difference （F=9.26， P<0.001）. The CX3CR1 protein relative expression levels were 1.99±0.21， 1.34±0.14， 2.73±0.31， respectively， with a statistically significant difference （F=8.14， P<0.001）. Further pair-to-pair comparisons showed that compared with the normal group， the relative expression levels of CX3CL1 and CX3CR1 protein in ovarian cancer model group were significantly decreased， and the relative expression levels of CX3CL1 and CX3CR1 protein were higher in CX3CL1 group （all P<0.05）. Compared with ovarian cancer model group， the relative expression levels of CX3CL1 and CX3CR1 protein in ovarian tissue of CX3CL1 group were significantly increased （both P<0.05）. Correlation analysis showed that CX3CL1 and CX3CR1 expressions were negatively correlated with peritoneal metastasis rate （r=-0.50， P=0.024； r=-0.58， P=0.012）. Conclusions The expression of chemokine CX3CL1/CX3CR1 is down-regulated in ovarian cancer， and CX3CL1/CX3CR1 expression is negatively correlated with peritoneal metastasis of ovarian cancer. Activation of CX3CL1/CX3CR1 can significantly inhibit peritoneal metastasis of ovarian cancer.

Key words: Chemokine CX3CL1, CX3C chemokine receptor 1, Ovarian neoplasms, Neoplasm metastasis