Aberrant Expression of IL-22 Receptor 1 and IL-22 Stimulation Increase the Activation of STAT3 and ERK1/2 in ABC-DLBCL Cells

BACKGROUND: Interleukin-22 (IL-22) was recently discovered as a T-cell derived cytokine that belongs to the IL-10 gene family. It has been shown that IL-22 can promote cell proliferation and activate several oncogenic pathways including STAT3, MAPK and AKT signaling. IL-22 exerts its function by binding to its heterodimeric receptor complex which is composed of IL-22 receptor (R) 1 and IL-10R2. IL-22R1 is restricted and barely detected in normal immune cells including B and T cells. In the current study, we sought to determine whether IL-22 plays a part in the development of diffuse large B-cell lymphoma (DLBCL).

METHODS: Plasma IL-22 level was measured in newly diagnosed patients with DLBCL and normal individuals by ELISA assay. We also assessed the expression of IL-22R1 in FFPE sample and DLBCL cell lines (TMD8, OCI-LY3, SUDHL16, OCI-LY1) by immunohistochemistry and immunofluorescence staining respectively. Immunoblotting was performed to determine changes of signaling pathways in cell lines upon the treatment with IL-22 recombinant protein.

RESULTS: The plasma IL-22 concentration was significantly increased in newly diagnosed DLBCL patients (n=12) compared with normal individuals (n=26, P= 0.0177). IL-22R1 protein was expressed in all of the four DLBCL cell lines, while not all but some of the primary tumor samples expressed it on membranes of tumor cells. Using immunoblotting, we demonstrated a substantial increase of pSTAT3 level with the treatment of IL-22 in ABC-DLBCL cell lines TMD8 and OCI-LY3, while no pSTAT3 was detectable in GCB-DLBCL cell lines SUDHL16 and OCI-LY1. Interestingly, upon IL-22 stimulation, the p-ERK1/2 level was increased shortly and quickly returned to the normal level in TMD8 cells, and steadily increased in LY3 cells during 30 min of treatment. However, there was no change about p-ERK1/2 in SUDHL16 and OCI-LY1 cells after IL-22 treatment.

CONCLUSIONS: Our current study has shown the aberrant expression of IL-22R1 in DLBCL. And recombinant IL-22 protein increased the activation of STAT3 and ERK1/2 in ABC rather than GCB-DLBCL cell lines. For the first time, we suggested the importance of IL-22 and its receptor IL-22R1 pathway in ABC-DLBCL, which warrants further studies.

Figure 1. The expression of IL-22R1 in DLBCL cell lines was detected by using immunofluorescence staining.