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

Abstract

Vesicular stomatitis virus (VSV) is a promising oncolytic virus (OV). Although VSV is effective against a majority of pancreatic ductal adenocarcinoma cell (PDAC) cell lines, some PDAC cell lines are highly resistant to VSV, and the mechanisms of resistance are still unclear. JAK1/2 inhibitors (such as ruxolitinib and JAK inhibitor I) strongly stimulate VSV replication and oncolysis in all resistant cell lines but only partially improve the susceptibility of resistant PDACs to VSV. VSV tumor tropism is generally dependent on the permissiveness of malignant cells to viral replication rather than on receptor specificity, with several ubiquitously expressed cell surface molecules playing a role in VSV attachment to host cells. However, as VSV attachment to PDAC cells has never been tested before, here we examined if it was possibly inhibited in resistant PDAC cells. Our data show a dramatically weaker attachment of VSV to HPAF-II cells, the most resistant human PDAC cell line. Although sequence analysis of low-density lipoprotein (LDL) receptor (LDLR) mRNA did not reveal any amino acid substitutions in this cell line, HPAF-II cells displayed the lowest level of LDLR expression and dramatically lower LDL uptake. Treatment of cells with various statins strongly increased LDLR expression levels but did not improve VSV attachment or LDL uptake in HPAF-II cells. However, LDLR-independent attachment of VSV to HPAF-II cells was dramatically improved by treating cells with Polybrene or DEAE-dextran. Moreover, combining VSV with ruxolitinib and Polybrene or DEAE-dextran successfully broke the resistance of HPAF-II cells to VSV by simultaneously improving VSV attachment and replication.IMPORTANCE Oncolytic virus (OV) therapy is an anticancer approach that uses viruses that selectively infect and kill cancer cells. This study focuses on oncolytic vesicular stomatitis virus (VSV) against pancreatic ductal adenocarcinoma (PDAC) cells. Although VSV is effective against most PDAC cells, some are highly resistant to VSV, and the mechanisms are still unclear. Here we examined if VSV attachment to cells was inhibited in resistant PDAC cells. Our data show very inefficient attachment of VSV to the most resistant human PDAC cell line, HPAF-II. However, VSV attachment to HPAF-II cells was dramatically improved by treating cells with polycations. Moreover, combining VSV with polycations and ruxolitinib (which inhibits antiviral signaling) successfully broke the resistance of HPAF-II cells to VSV by simultaneously improving VSV attachment and replication. We envision that this novel triple-combination approach could be used in the future to treat PDAC tumors that are highly resistant to OV therapy.KEYWORDS DEAE-dextran, combination treatment, oncolytic virus, pancreatic cancer, Polybrene, polycation, resistance, vesicular stomatitis virus, virus attachment, type I interferon, ruxolitinib

Recent advances in vesicular stomatitis virus-based oncolytic virotherapy: a 5-year update

“…Recently, we demonstrated that the most resistant human PDAC cell line in our study, HPAF-II, showed dramatically weaker attachment of VSV independently of type I IFN signalling [85]. Polycation (polybrene or DEAE-dextran) treatment considerably improved attachment of VSV to HPAF-II.…”

“…Polycation (polybrene or DEAE-dextran) treatment considerably improved attachment of VSV to HPAF-II. Moreover, combining VSV with polycations and ruxolitinib (JAK1/JAK2 inhibitor) successfully broke the resistance of HPAF-II to VSV by concurrently improving VSV attachment and replication [85].…”

Experimental Evolution Generates Novel Oncolytic Vesicular Stomatitis Viruses with Improved Replication in Virus-Resistant Pancreatic Cancer Cells

“…SUIT-2 cells are more resistant to VSV infection in part because of residual type I IFN responses, yet permissive enough to support sufficient viral replication to produce enough viral progeny for continued viral passaging, while MIA PaCa-2 cells are very permissive to VSV infection in part due to their inactive type I IFN signaling (37,41,66). Also, we showed that SUIT-2 cells showed lower levels of VSV attachment, compared to MIA PaCa-2 cells (44). Each virus has a large transgene (about 17% of the WT VSV genome) encoding a different version of p53 fused to RFP.…”

“…First, SUIT-2 cells are able to induce a functional type I IFN response to VSV (37,41,66). Second, we observed that, compared to MIA PaCa-2 and some other tested PDAC cell lines, VSV attaches less efficiently to SUIT-2 cells (44). Therefore, we hypothesized that extensive passaging of VSV on SUIT-2 cells selected for spontaneous VSV mutants via the following mechanisms: (i) an improved ability to evade type I IFN signaling and/or (ii) improved attachment to SUIT-2 cells.…”

“…Our previous studies showed that pancreatic ductal adenocarcinoma (PDAC) cell lines show great diversity in susceptibility and permissibility to VSV-based OVs, such as VSV-ΔM51. We previously identified several mechanisms behind resistance of PDACs to VSV-based therapy, such as abnormal or residual type I IFN antiviral activities (40)(41)(42)(43), inefficient attachment of VSV to some PDACs (44), and resistance of VSV-infected PDAC cells to virus-mediated apoptosis (45).…”