Long non-coding RNA SNHG12 promotes immune escape of ovarian cancer cells through their crosstalk with M2 macrophages

Accumulating evidence shows that the tumor microenvironment contributes to this phenomenon and that long non-coding RNAs (lncRNAs) are also involved in this process. In this study, we identified a new lncRNA small nucleolar RNA host gene 12 (SNHG12) and investigated its role in tumor immune escape. We analyzed the expression levels of interlukin (IL)-6R and programmed death-ligand 1 (PD-L1) in 51 ovarian cancer and 20 normal specimens by immunohistochemistry. The correlation between SNHG12 and IL-6R in clinical ovarian cancer samples was identified by RT-qPCR. We then performed SNHG12 gain- and loss-function experiments in order to investigate its role in the regulation of immune escape and the crosstalk between miR-21 and IL-6. T cell proliferation was assessed by flow cytometry. In vivo pro-immune escape activity of SNHG12 was assessed by tumor-xenograft mouse model. IL-6R and PD-L1 were found to be overexpressed in clinical ovarian cancer specimens. Meanwhile, SNHG12 and IL-6R expressions were positively correlated in clinical ovarian cancer samples. SNHG12 facilitated ovarian immune escape by promoting IL-6/miR-21 crosstalk between ovarian cancer cells and M2 macrophages. Notably, SNHG12 promoted IL-6R transcription by recruiting NF-κB1 to the IL-6R promoter. Our study reveals that SNHG12 facilitates ovarian cancer immune escape by upregulating IL-6R.