Breaking resistance of pancreatic cancer cells to an attenuated vesicular stomatitis virus through a novel activity of IKK inhibitor TPCA-1

Abstract

Vesicular stomatitis virus (VSV) is an effective oncolytic virus against most human pancreatic ductal adenocarcinoma (PDAC) cell lines. However, some PDAC cell lines are highly resistant to oncolytic VSV-ΔM51 infection. To better understand the mechanism of resistance, we tested a panel of 16 small molecule inhibitors of different cellular signaling pathways, and identified TPCA-1 (IKK-β inhibitor) and ruxolitinib (JAK1/2 inhibitor), as strong enhancers of VSV-ΔM51 replication and virus-mediated oncolysis in all VSV-resistant PDAC cell lines. Both TPCA-1 and ruxolitinib similarly inhibited STAT1 and STAT2 phosphorylation and decreased expression of antiviral genes MxA and OAS. Moreover, an in situ kinase assay provided biochemical evidence that TPCA-1 directly inhibits JAK1 kinase activity. Together, our data demonstrate that TPCA-1 is a unique dual inhibitor of IKK-β and JAK1 kinase, and provide a new evidence that upregulated type I interferon signaling plays a major role in resistance of pancreatic cancer cells to oncolytic viruses.

Ruxolitinib and Polycation Combination Treatment Overcomes Multiple Mechanisms of Resistance of Pancreatic Cancer Cells to Oncolytic Vesicular Stomatitis Virus

“…cell lines (27)(28)(29). In agreement with this observation, pretreatment of cells with ruxolitinib (compared to posttreatment only) did not change the kinetics of VSV replication, with a significant increase in VSV replication that could be seen only at 48 h postinfection (p.i.…”

“…previous studies demonstrating that VSV-resistant PDAC cell lines (such as HPAF-II and Hs766T) have upregulated type I IFN signaling and constitutive expression of a subset of ISGs, whereas VSV-permissive PDAC cell lines (such as MIA PaCa-2 and Suit2) do not (26)(27)(28)(29). Interestingly, even though Hs766T cells had a level of VSV attachment similar to that in MIA PaCa-2 cells and even higher than that in Suit2 cells (about 3.5-fold higher based on serial dilution of the virus) (Fig.…”

“…The human PDAC cell line HPAF-II, which showed the highest level of resistance to VSV in our previous studies, was the main focus of this study (26)(27)(28)(29)(30). In addition, many experiments included Hs766T, another VSV-resistant human PDAC cell line, as well as two VSV-permissive human PDAC cell lines, MIA PaCa-2 and Suit2.…”

“…Our previous studies demonstrated that upregulated type I IFN signaling plays an important role in the resistance of PDAC cell lines to VSV (26)(27)(28)(29) and that treatment of resistant PDAC cell lines with ruxolitinib (a specific JAK1/2 inhibitor) dramatically inhibits antiviral signaling and improves VSV replication in all resistant PDAC cell lines (28,29). To examine whether the observed inefficient binding of VSV to HPAF-II cells is a result of type I IFN pathway upregulation, HPAF-II and Suit2 (as a negative control) cells were pretreated with ruxolitinib for 24 h before VSV attachment to cell monolayers was assayed.…”

“…In agreement with this observation, pretreatment of cells with ruxolitinib (compared to posttreatment only) did not change the kinetics of VSV replication, with a significant increase in VSV replication that could be seen only at 48 h postinfection (p.i. ), even in cells pretreated with ruxolitinib for up to 48 h, suggesting that ruxolitinib did not improve the rate of initial infection but rather facilitated secondary infection via the inhibition of antiviral signaling in PDAC cells (28,29).…”