Tumor progression (Figure 6a, left). However, the Reolysin and BZ combination led to a dramatic decrease in tumor burden (Figure 6a, left) that was markedly greater than what was achieved with either monotherapy. Moreover, the combination treatment was well tolerated as no significant animal weight loss was observed at the completion of the study (day 38) (Figure 6a, right). We next evaluated whether we could detect the presence of reovirus inside Panc-1 tumors treated with the combination. Consistent with our in vitro data, reovirus was readily detected in Reolysin-treated tumors by electron microscopy (Figure 6b). Notably, reovirus was present to an equivalent extent in tumors treated with Reolysin alone and Reolysin plus BZ, suggesting that BZ does not alter reovirus replication. In agreement with our related in vitro assays, immunohistochemical analysis of tumor sections revealed a significant increase in BiP expression (Figure 6c) and apoptosis (Figure 6d) in mice treated with Reolysin and BZ. Collectively, these data provide evidence that Reolysin induces ER stress and possesses significant activity in models of Ras-activated pancreatic cancer that can be augmented via further induction of ER stress with BZ.Discussion Reovirus is an oncolytic virus that has been reported to selectively replicate in cells with an activated Ras pathway.12,13 Given the very high prevalence of Ras mutations in pancreatic cancer, patients with KRas-positive pancreatic tumors may be intrinsically sensitive to reovirus treatment. The results of our current investigation are consistent with previous findings in different cancer types that also demonstrated that reovirus preferentially replicates in Ras-transformed cells.Narsoplimab 12,17,24,25 Our data show that reovirus selectively replicated in KRas-transfected normal pancreatic epithelial cells versus KRas-negative HPNE cells, indicating that Ras activity is a key determinant regulating Reolysin sensitivity.Taurine Although it is clear that Reolysin possesses significant activityFigure 3 Reolysin promotes caspase-4 processing and apoptosis and sensitizes cells to ER stress-mediated apoptosis.PMID:35126464 (a) Reolysin decreases cell viability in a panel of pancreatic cancer cell lines. Cells were treated with the indicated concentrations of Reolysin for 72 h. Cell viability was measured by MTT assay. Mean .D., n 3. (b) Reolysin promotes cleavage of caspase-4 and caspase-3. Panc-1 cells were treated with the indicated concentrations of Reolysin for 48 h, and caspase cleavage was measured by immunoblotting. Arrows denote cleaved caspase-4 fragments. (c) Reolysin induces apoptosis. Panc-1 and CFPAC1 cells were treated with Reolysin for 48 h. Apoptosis was measured by PI-FACS analysis. Mean .D., n 3. *Indicates a significant difference compared with controls. (d) Reolysin augments ER stress-mediated apoptosis. Panc-1 cells were treated for 48 h with 300 PFU/cell Reolysin, 5 mg/ml tunicamycin, 5 mM brefeldin A, and combinations. Mean .D., n 3. *Indicates a significant difference compared with controls; **indicates a significant difference compared with either single-agent treatment Po0.Cell Death and DiseaseReovirus induces ER stress JS Carew et alFigure 4 Reolysin augments the anticancer activity of BZ. (a and b) Reolysin and BZ stimulate reoviral and ubiquitinated protein accumulation. Cells were treated with 100 PFU/cell Reolysin and 10 nM BZ for 48 h. Protein accumulation was visualized by (a) immunocytochemistry and (b) electron micr.
