Increased expression of CX3CL1 and CX3CR1 in papillary thyroid carcinoma

CX3CL1 and its receptor CX3CR1 axis are involved in the development, progression and metastasis of many types of cancers. It has been reported that CX3CL1 and CX3CR1 expression was upregulated in some solid tumors. However, their roles in thyroid cancer remain unknown. In the present study, we investigated the expression of CX3CL1 and CX3CR1 in human papillary thyroid carcinoma (PTC) and their clinical significance. In this study, using immunohistochemistry, we examined the expression of CX3CL1 and CX3CR1 in the tissues of 26 human PTC (including 17 classical or conventional (CPTC) and 9 follicular (FVPTC) variants of PTC; 15 cases without and 11 cases with lymph node metastasis) and 10 cases of nodular goiter (NG). Compared to NG, a significant increase in the expression of CX3CL1 and CX3CR1 was found in PTC overall, as well as in CPTC and FVPTC separately. Higher CX3CL1 expression was found in CPTC than in FVPTC, but there was no significant difference in CX3CR1 expression between these subtypes of PTC. When analyzing their expressions in PTC without and with lymph node metastasis, an increased expression of CX3CL1 and CX3CR1 was observed when compared to NG respectively. There was however no significant difference in CX3CL1 and CX3CR1 expressions in PTC without lymph node metastasis when compared to PTC with lymph node metastasis. Furthermore, when compared to NG, an increased expression of CX3CL1 was correlated with an increased expression of CX3CR1 in PTC. Our data indicate that CX3CL1 and CX3CR1 can be used as tumor markers for PTC and may be potential novel targets for cancer prevention and treatment.