C-REV Retains High Infectivity Regardless of the Expression Levels of cGAS and STING in Cultured Pancreatic Cancer Cells

Oncolytic virus (OV) therapy is widely considered as a major breakthrough in anti-cancer treatments. In our previous study, the efficacy and safety of using C-REV for anti-cancer therapy in patients during stage I clinical trial was reported. The stimulator of interferon genes (STING)–TBK1–IRF3–IFN pathway is known to act as the central cellular host defense against viral infection. Recent reports have linked low expression levels of cGAS and STING in cancer cells to poor prognosis among patients. Moreover, downregulation of cGAS and STING has been linked to higher susceptibility to OV infection among several cancer cell lines. In this paper, we show that there is little correlation between levels of cGAS/STING expression and susceptibility to C-REV among human pancreatic cancer cell lines. Despite having a responsive STING pathway, BxPC-3 cells are highly susceptible to C-REV infection. Upon pre-activation of the STING pathway, BxPc-3 cells exhibited resistance to C-REV infection. However, without pre-activation, C-REV completely suppressed the STING pathway in BxPC-3 cells. Additionally, despite harboring defects in the STING pathway, other high-grade cancer cell lines, such as Capan-2, PANC-1 and MiaPaCa-2, still exhibited low susceptibility to C-REV infection. Furthermore, overexpression of STING in MiaPaCa-2 cells altered susceptibility to a limited extent. Taken together, our data suggest that the cGAS–STING pathway plays a minor role in the susceptibility of pancreatic cancer cell lines to C-REV infection.