Application of the chemokine-chemokine receptor axis increases the tumor-targeted migration ability of cytokine-induced killer cells in patients with colorectal cancer

Cytokine-induced killer (CIK) cells are a group of heterogeneous immune cells which can be isolated from human peripheral blood mononuclear cells and have demonstrated therapeutic benefit both in hematologic malignancies and solid tumors, including colorectal cancer. However, poor tumor-targeted migration has limited the clinical efficacy of CIK cell treatment. The chemokine-chemokine receptor (CK-CKR) axis serves a role in the tumor-directed trafficking capacity of immune cells. Investigating the relationship between CKR profiles on the surface of CIK cells and chemokine expression levels in the tumor microenvironment may improve CIK cell therapy. In the present study, the spectrum of chemokine expression levels in tumor tissues from patients with colorectal cancer (CRC) and CKR expression profiles in CIK cells obtained from the same individuals with CRC were investigated. The results showed that chemokine expression levels in tumor tissues exhibited variability and cell line heterogeneity. However, the expression levels of a number of chemokines were similar in different CRC donors and cell lines. Expression levels of CXCLL10, CXCL11 and CCL3 were significantly higher in most tumor tissues compared with adjacent normal tissues and highly expressed in most CRC cell lines. In accordance with chemokine expression levels, CKR profiles on the surface of CIK cells also showed donor-to-donor variability. However, concordant expression profiles of CKRs were identified in different patients with CRC. CXCR3 and CXCR4 were highly expressed on the surface of CIK cells through the culture process. Importantly, the expression levels of all CKRs, especially CCR4, CXCR4 and CXCR3, were notably decreased during the course of CIK cell expansion. The changing trend of CKR profiles were not correlated with the chemokine expression profiles in CRC tissues (CCL3, CXCL12 and CXCL10/CXCL11 were highly expressed in CRC tissue). Re-stimulating CIK cells using chemokines (CCL21 and CXCL11) at the proper time point increased corresponding CKR expression levels on the surface of CIK cells and enhance tumor-targeted trafficking in vitro. These results demonstrated that modification of the CK-CKR axis using exogenous recombinant chemokines at the proper time point enhanced CIK cell trafficking ability and improved CIK antitumor effects.