Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China.
Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China; Department of Radiotherapy, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China; Department of Oncology, Yancheng Third People's Hospital, Yancheng, 224006, China.
Pancreatology. 2018 Oct;18(7):822-832. doi: 10.1016/j.pan.2018.08.007. Epub 2018 Aug 24.
Cantharidin is an inhibitor of protein phosphatase 2 A (PP2A), and has been frequently used in clinical practice. In our previous study, we proved that cantharidin could arrest cell cycle in G2/M phase. Since cells at G2/M phase are sensitive to radiotherapy, in the present study, we investigated the radiotherapy-sesitization effect of cantharidin and the potential mechanisms involved.
Cell growth was determined by MTT assay. Cell cycle was evaluated by flow cytometry. DNA damage was visualized by phospho-Histone H2A.X staining. Expression of mRNA was tested by microarray assay and real-time PCR. Clinical information and RNA-Seq expression data were derived from The Cancer Genome Atlas (TCGA) pancreatic cancer cohort. Survival analysis was obtained by Kaplan-Meier estimates.
Cantharidin strengthened the growth inhibition effect of irradiation. Cantharidin drove pancreatic cancer cells out of quiescent G0/G1 phase and arrested cell cycle in G2/M phase. As a result, cantharidin strengthened DNA damage which was induced by irradiation. Moreover, cantharidin repressed expressions of several genes participating in DNA damage repair, including UBE2T, RPA1, GTF2HH5, LIG1, POLD3, RMI2, XRCC1, PRKDC, FANC1, FAAP100, RAD50, RAD51D, RAD51B and DMC1, through JNK, ERK, PKC, p38 and/or NF-κB pathway dependent manners. Among these genes, worse overall survival for pancreatic cancer patients were associated with high mRNA expressions of POLD3, RMI2, PRKDC, FANC1, RAD50 and RAD51B, all of which could be down-regulated by cantharidin.
Cantharidin can sensitize pancreatic cancer cells to radiotherapy. Multiple mechanisms, including cell cycle regulation, enhanced DNA damage, and inhibited DNA damage repair, may be involved.
斑蝥素是蛋白磷酸酶 2A（PP2A）的抑制剂，在临床实践中被广泛应用。在我们之前的研究中，我们证明了斑蝥素可以将细胞周期阻滞在 G2/M 期。由于 G2/M 期的细胞对放疗敏感，因此在本研究中，我们研究了斑蝥素的放疗增敏作用及其潜在机制。
通过 MTT 法测定细胞生长情况。通过流式细胞术评估细胞周期。通过磷酸化组蛋白 H2A.X 染色观察 DNA 损伤。通过微阵列分析和实时 PCR 检测 mRNA 表达。临床信息和 RNA-Seq 表达数据来自癌症基因组图谱（TCGA）胰腺癌症队列。通过 Kaplan-Meier 估计进行生存分析。
斑蝥素增强了照射的生长抑制作用。斑蝥素将胰腺癌细胞从静止的 G0/G1 期驱出，并将细胞周期阻滞在 G2/M 期。结果，斑蝥素增强了照射诱导的 DNA 损伤。此外，斑蝥素通过 JNK、ERK、PKC、p38 和/或 NF-κB 通路依赖性方式抑制了参与 DNA 损伤修复的几个基因的表达，包括 UBE2T、RPA1、GTF2HH5、LIG1、POLD3、RMI2、XRCC1、PRKDC、FANC1、FAAP100、RAD50、RAD51D、RAD51B 和 DMC1。在这些基因中，POLD3、RMI2、PRKDC、FANC1、RAD50 和 RAD51B 的高 mRNA 表达与胰腺癌症患者的总体生存率较差相关，而这些基因均可被斑蝥素下调。
斑蝥素可以使胰腺癌细胞对放疗敏感。多种机制，包括细胞周期调控、增强 DNA 损伤和抑制 DNA 损伤修复，可能参与其中。
