Objective:To investigate the expression pattern,clinical significance,and the regulatory role of 2',5'-oligoadenylate synthetase 1(OAS1)in the proliferation of pancreatic ductal adenocarcinoma(PDAC)cells.Methods:Public databases such as Gene Expression Omnibus(GEO)and The Cancer Genome Atlas(TCGA)were used to analyze the expression of OAS1 in pancreatic cancer tissues.Immunohistochemical staining was applied to validate the expression level of OAS1 in PDAC tissue microarrays,and the association between OAS1 expression level and the prognosis of patients was analyzed.Real-time fluorescence quantitative PCR was performed to examine the expression level of OAS1 mRNA in different PDAC cell lines.CCK-8 assay and colony formation assay was used to assess the effect of OAS1 on the proliferation of PDAC cells after OAS1 silencing in Patu-8988 and PDC0034 cells by siRNA treatment.Further,Gene Set enrichment analysis(GSEA)was performed to screen for possible molecular mechanism of the regulatory role of OAS1 in PDAC.Cell viability and cholesterol level was analyzed after treatment with mTOR signaling activator MHY1485 in OAS1-silenced Patu-8988 and PDC0034 cells in order to verify the underlying mechanism of the regulatory role of OAS1 in PDAC cell proliferation.Results:Database analysis showed significant upregulation of OAS1 expression in pancreatic cancer tissues(P<0.05).Immunohistochemical staining results from PDAC tissue microarray showed that OAS1 expression was significantly upregulated in PDAC tissues compared with the paired paracancerous tissues,and high OAS1 expression was associated with poor prognosis(P<0.05).Real-time fluorescence quantitative PCR and Western blotting analysis show that OAS1 expression was higher in PDAC cells lines compared with normal ductal cells of the pancreas.The proliferative activity of PDAC cells decreased significantly after OAS1 silencing in Patu-8988 and PDC0034 cells(P<0.001).GSEA results indicated that OAS1 may affect PDAC cell proliferation through mTOR signaling pathway and cholesterol metabolism associated pathway.The mTOR signaling pathway may be inhibited and the total cellular cholesterol decreased after OAS1 silencing.Treatment with mammalian target of rapamycin(mTOR)activator MHY1485 partially reversed the inhibitory effect of OAS1 silencing on the proliferation and cholesterol metabolism of PDAC cells.Conclusion:OAS1 expression is upregulated in PDAC tumor tissues and cells and is associated with poor prognosis.OAS1 may promote the proliferation of pancreatic cancer cells by enhancing cholesterol metabolism through activation of the mTOR signaling pathway.

Objective:To investigate the expression pattern,clinical significance,and the regulatory role of 2',5'-oligoadenylate synthetase 1(OAS1)in the proliferation of pancreatic ductal adenocarcinoma(PDAC)cells.Methods:Public databases such as Gene Expression Omnibus(GEO)and The Cancer Genome Atlas(TCGA)were used to analyze the expression of OAS1 in pancreatic cancer tissues.Immunohistochemical staining was applied to validate the expression level of OAS1 in PDAC tissue microarrays,and the association between OAS1 expression level and the prognosis of patients was analyzed.Real-time fluorescence quantitative PCR was performed to examine the expression level of OAS1 mRNA in different PDAC cell lines.CCK-8 assay and colony formation assay was used to assess the effect of OAS1 on the proliferation of PDAC cells after OAS1 silencing in Patu-8988 and PDC0034 cells by siRNA treatment.Further,Gene Set enrichment analysis(GSEA)was performed to screen for possible molecular mechanism of the regulatory role of OAS1 in PDAC.Cell viability and cholesterol level was analyzed after treatment with mTOR signaling activator MHY1485 in OAS1-silenced Patu-8988 and PDC0034 cells in order to verify the underlying mechanism of the regulatory role of OAS1 in PDAC cell proliferation.Results:Database analysis showed significant upregulation of OAS1 expression in pancreatic cancer tissues(P<0.05).Immunohistochemical staining results from PDAC tissue microarray showed that OAS1 expression was significantly upregulated in PDAC tissues compared with the paired paracancerous tissues,and high OAS1 expression was associated with poor prognosis(P<0.05).Real-time fluorescence quantitative PCR and Western blotting analysis show that OAS1 expression was higher in PDAC cells lines compared with normal ductal cells of the pancreas.The proliferative activity of PDAC cells decreased significantly after OAS1 silencing in Patu-8988 and PDC0034 cells(P<0.001).GSEA results indicated that OAS1 may affect PDAC cell proliferation through mTOR signaling pathway and cholesterol metabolism associated pathway.The mTOR signaling pathway may be inhibited and the total cellular cholesterol decreased after OAS1 silencing.Treatment with mammalian target of rapamycin(mTOR)activator MHY1485 partially reversed the inhibitory effect of OAS1 silencing on the proliferation and cholesterol metabolism of PDAC cells.Conclusion:OAS1 expression is upregulated in PDAC tumor tissues and cells and is associated with poor prognosis.OAS1 may promote the proliferation of pancreatic cancer cells by enhancing cholesterol metabolism through activation of the mTOR signaling pathway.