Relationship between CCL20/CCR6/Th17 axis and vascular invasion and metastasis in patients with primary hepatocellular carcinoma

Abstract

To investigate the role of CCL20/CCR6/Th17 axis in vascular invasion and metastasis of primary hepatocellular carcinoma (HCC). Expression levels of CCL20 mRNA in the normal human liver cell line L-02, and human hepatocellular carcinoma cell lines Hep3B, Huh7 and HepG2 were quantified by using SYBR green real time PCR. CCL20 secretions from these cell lines were quantified by using ELISA. The chemotactic effect of HCC cell line Hep3B on human peripheral blood mononuclear cells was determined by using transwell chemotaxis assay. Pre-therapy serum levels of IL-1α, IL-1β, IL-6, IL-8, IL-10, IL-17, IL-23, IFN-γ, TNF-α and CCL20 in 93 patients with HCC were measured by using 9-plex array and ELISA. All the patients were chronic hepatitis B virus associated HCC, and 51 cases were those with vascular invasion and metastasis (metastasis group) and 42 cases were not (non-metastasis group). CCL20 and CCR6 mRNA expressions in the HCC and tumor-adjacent tissues were determined by using SYBR Green real time PCR in 41 patients, among them, 20 cases were from the group of patients with metastasis and 21 cases were from the group of patients without metastasis. The CCL20 expression was further determined by immunohistochemistry. The HCC cell lines expressed and secreted higher amount of CCL20, which effectively recruited CCR6(+) T cells. Pre-therapy serum levels of CCL20 in 93 HCC patients were (38.2 ± 28.4)pg/ml, significantly increased than those with benign hepatic hemangiomas [(7.8 ± 17.8)pg/ml, P < 0.01]. In addition, the serum levels of CCL20 were positively correlated with the tumor diameters in HCC patients (r = 0.32, P = 0.0018). CCL20 was dominantly expressed in the cytoplasm in HCC cells, and it was also expressed by some infiltrating immune cells. The mRNA expression levels of CCL20 of the tumor tissues were significantly higher than that in the tumor-adjacent tissues (P < 0.05). Multivariate logistic regression analysis showed that serum levels of IL-17 and CCL20 were independent risk factors of metastasis in HCC patients (P < 0.05 for both). CCL20 mRNA showed no statistically significant differences between patients with metastasis and without metastasis in both tumor tissues and tumor-adjacent tissues (P > 0.05 for both). But the patients with metastasis showed significantly higher expressions of CCR6 both in their tumor [5.75 (1.79, 19.13)]and tumor-adjacent tissues [7.99 (4.49, 19.54)] than those with non-metastasis [1.69 (0.76, 2.87) and 3.58 (1.84, 4.32), P < 0.05 for both]. CCL20/CCR6/Th17 axis may promote vascular invasion and metastasis hepatocellular carcinoma.