Interleukin 37 Expression Inhibits STAT3 to Suppress the Proliferation and Invasion of Human Cervical Cancer Cells

The most recently discovered cytokine interleukin 37 (IL-37) received growing attention. Its function on tumor is largely unknown. Here, we investigated the biological function of IL-37 on cervical cancer (CC). Materials and methods : HPV(+) Hela cells and HPV(-) C33A cells were used. RT-qPCR was performed to detect the transcription of IL-37, STAT3, TNF-αand IL-1β. Western blotting was used for protein detection. CCK-8 assay and transwell assay were employed for cell proliferation and invasion detection, respectively. Results : Successful gene transfection of IL-37 suppressed the proliferation and invasion of CC. Interestingly, IL-37 showed higher anticancer ability in HPV(+) Hela cells than that in HPV(-) C33A cells. Then, the molecular mechanism of IL-37 anticancer was explored. Firstly, we found that IL-37 inhibited STAT3 expression at both mRNA and protein levels. IL-37 also down regulated the phosphorylation of STAT3. Secondly, blockage of STAT3 using siRNAs reduced significantly the ability of IL-37 to suppress cell proliferation and invasion. Thirdly, STAT3 knockdown reduced markedly the inhibition of IL-37 on the transcription of tumor-derived TNF-α and IL-1β, indicating the contribution of STAT3 for the cancer associated antiinflammation of IL-37. Finally, STAT3 up regulation restored the ability of cell proliferation, cell invasion and the expression of inflammatory cytokines, TNF-α and IL-1β. Conclusions : IL-37 suppressed cell proliferation and invasion of CC and STAT3 is involved in this process. Thus, IL-37 emerges as a new anticancer cytokine for CC. This study demonstrated a new biological function of IL-37 and offered a potential molecule for CC treatment.