IFN-γ Induced Up-regulation Of RFXAP In Pancreatic Cancer Cell: A Novel Mechanism For IFN-γ Response

Objective:Interferon(IFN)-γ can induce the expression of MHC class Ⅱ in various cells. However, as an important transcription factor for MHC class Ⅱ, the expression of regulatory factor X-associated protein (RFXAP) was remain unclear by the stimulation of IFN-γ. We propose the hypotheses that in tumor cell lines RFXAP may play an important role in IFN-γ induced MHC Ⅱ expression.Methods:After stimulation of IFN-γ, expression of miR-212-3p was determined by PCR, expression of RFXAP and MHC class Ⅱ was determined by Western Blot. Luciferase assays and transfection assays were used to confirm the association between RFXAP and miR-212-3p. Besides, after Panc-1 cells transfected with miR-212-3p mimic, expression of RFXAP and MHC class Ⅱ was detected by Western Blot.ResultsmiR-212-3p expression was inhibited by IFN-γ in a dose and time-dependent manner, meanwhile, RFXAP and MHC class Ⅱ expression were both increased after IFN-γ stimulation. Luciferase assay was performed to validate RFXAP as miR-212-3p target. miR-212-3p mimic, inhibitor or negative control were transfected into pancreatic cancer cells and the up-regulation and down-regulation of RFXAP and MHC class Ⅱ were observed, respectively. However IFN-γ stimulation could not increase the expression of RFXAP and MHC class Ⅱ after Panc-1 cells transfected with miR-212-3p mimic.Conclusion:We concluded that the inhibition of miR-212-3p by IFN-γ induced the MHC class Ⅱ expression, and RFXAP was a direct downstream target of miR-212-3p. In addition, RFXAP was firstly found up-regulated in IFN-γ system. As a novel transcription factor, RFXAP may also bind some other genes. This may be a novel mechanism for IFN-γ in pancreatic ductal adenocarcinoma (PDAC) immunotherapy.