Abstract：
OBJECTIVE: Due to the high intrinsic radioresistance of pancreatic ductal adenocarcinoma (PDAC), radiotherapy (RT) is only beneficial in 30% of patients. Therefore, this study aimed to identify targets to improve the efficacy of RT in PDAC.
METHODS: Alamar Blue proliferation and colony formation assay (CFA) were used to determine the radioresponse of a cohort of 38 murine PDAC cell lines. A gene set enrichment analysis was performed to reveal differentially expressed pathways. CFA, cell cycle distribution, γH2AX FACS analysis, and Caspase 3/7 SYTOX assay were used to examine the effect of a combination treatment using KIRA8 as an IRE1α-inhibitor and Ceapin-A7 as an inhibitor against ATF6.
RESULTS: The unfolded protein response (UPR) was identified as a pathway highly expressed in radioresistant cell lines. Using the IRE1α-inhibitor KIRA8 or the ATF6-inhibitor Ceapin-A7 in combination with radiation, a radiosensitizing effect was observed in radioresistant cell lines, but no substantial alteration of the radioresponse in radiosensitive cell lines. Mechanistically, increased apoptosis by KIRA8 in combination with radiation and a cell cycle arrest in the G1 phase after ATF6 inhibition and radiation have been observed in radioresistant cell lines.
CONCLUSIONS: So, our data show evidence that the UPR is involved in radioresistance of PDAC. Increased apoptosis and a G1 cell cycle arrest seem to be responsible for the radiosensitizing effect of UPR inhibition. These findings are supportive for developing novel combination treatment concepts in PDAC to overcome radioresistance.
METHODS: Alamar Blue proliferation and colony formation assay (CFA) were used to determine the radioresponse of a cohort of 38 murine PDAC cell lines. A gene set enrichment analysis was performed to reveal differentially expressed pathways. CFA, cell cycle distribution, γH2AX FACS analysis, and Caspase 3/7 SYTOX assay were used to examine the effect of a combination treatment using KIRA8 as an IRE1α-inhibitor and Ceapin-A7 as an inhibitor against ATF6.
RESULTS: The unfolded protein response (UPR) was identified as a pathway highly expressed in radioresistant cell lines. Using the IRE1α-inhibitor KIRA8 or the ATF6-inhibitor Ceapin-A7 in combination with radiation, a radiosensitizing effect was observed in radioresistant cell lines, but no substantial alteration of the radioresponse in radiosensitive cell lines. Mechanistically, increased apoptosis by KIRA8 in combination with radiation and a cell cycle arrest in the G1 phase after ATF6 inhibition and radiation have been observed in radioresistant cell lines.
CONCLUSIONS: So, our data show evidence that the UPR is involved in radioresistance of PDAC. Increased apoptosis and a G1 cell cycle arrest seem to be responsible for the radiosensitizing effect of UPR inhibition. These findings are supportive for developing novel combination treatment concepts in PDAC to overcome radioresistance.
摘要：
目的：由于胰腺导管腺癌（PDAC）的高固有辐射抗性，放疗（RT）仅对30％的患者有益。因此,本研究旨在确定改善RT在PDAC中疗效的靶点.
方法:AlamarBlue增殖和集落形成试验(CFA)用于测定一组38只鼠PDAC细胞系的放射反应。进行基因集富集分析以揭示差异表达的途径。CFA,细胞周期分布，γH2AXFACS分析，和半胱天冬酶3/7SYTOX测定用于检查使用KIRA8作为IRE1α抑制剂和Ceapin-A7作为ATF6抑制剂的组合治疗的效果。
结果：未折叠蛋白反应（UPR）被鉴定为在耐放射细胞系中高度表达的途径。使用IRE1α抑制剂KIRA8或ATF6抑制剂Ceapin-A7与辐射联合使用，在抗放射性细胞系中观察到放射增敏作用，但放射敏感细胞系的放射反应没有实质性改变。机械上,在抗辐射细胞系中观察到ATF6抑制和辐射后，KIRA8增加的细胞凋亡和G1期的细胞周期停滞。
结论：所以，我们的数据显示有证据表明UPR与PDAC的耐辐射性有关.凋亡增加和G1细胞周期停滞似乎是UPR抑制的放射增敏作用的原因。这些发现支持在PDAC中开发新的组合治疗概念以克服辐射抗性。
方法:AlamarBlue增殖和集落形成试验(CFA)用于测定一组38只鼠PDAC细胞系的放射反应。进行基因集富集分析以揭示差异表达的途径。CFA,细胞周期分布，γH2AXFACS分析，和半胱天冬酶3/7SYTOX测定用于检查使用KIRA8作为IRE1α抑制剂和Ceapin-A7作为ATF6抑制剂的组合治疗的效果。
结果：未折叠蛋白反应（UPR）被鉴定为在耐放射细胞系中高度表达的途径。使用IRE1α抑制剂KIRA8或ATF6抑制剂Ceapin-A7与辐射联合使用，在抗放射性细胞系中观察到放射增敏作用，但放射敏感细胞系的放射反应没有实质性改变。机械上,在抗辐射细胞系中观察到ATF6抑制和辐射后，KIRA8增加的细胞凋亡和G1期的细胞周期停滞。
结论：所以，我们的数据显示有证据表明UPR与PDAC的耐辐射性有关.凋亡增加和G1细胞周期停滞似乎是UPR抑制的放射增敏作用的原因。这些发现支持在PDAC中开发新的组合治疗概念以克服辐射抗性。
