Oike Takahiro, Komachi Mayumi, Ogiwara Hideaki, Amornwichet Napapat, Saitoh Yuka, Torikai Kohta, Kubo Nobuteru, Nakano Takashi, Kohno Takashi
Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan; Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Japan.
Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan.
Radiother Oncol. 2014 May;111(2):222-7. doi: 10.1016/j.radonc.2014.03.015. Epub 2014 Apr 17.
Chromatin remodeling through histone modifications, including acetylation, plays an important role in the appropriate response to DNA damage induced by ionizing radiation (IR). Here we investigated the radiosensitizing effect of C646, a selective small molecule inhibitor of p300 histone acetyltransferase, and explored the underlying mechanisms.
A549, H157 and H460 human non-small cell lung carcinoma (NSCLC) cells, and HFL-III human lung fibroblasts were assessed by clonogenic survival assay. Apoptosis and necrosis were assessed by annexin V staining. Senescence was assessed by Senescence-associated β-galactosidase staining. Mitotic catastrophe was assessed by evaluating nuclear morphology with DAPI staining. Cell cycle profiles were analyzed by flow cytometry. Protein expression was analyzed by immunoblotting.
C646 sensitized A549, H460 and H157 cells to IR with a dose enhancement ratio at 10% surviving fraction of 1.4, 1.2 and 1.2, respectively. C646 did not radiosensitize HFL-III cells. In A549 cells, but not in HFL-III cells, C646 (i) enhanced mitotic catastrophe but not apoptosis, necrosis, or senescence after IR; (ii) increased the hyperploid cell population after IR; and (iii) suppressed the phosphorylation of CHK1 after IR.
C646 radiosensitizes NSCLC cells by enhancing mitotic catastrophe through the abrogation of G2 checkpoint maintenance.
通过包括乙酰化在内的组蛋白修饰进行染色质重塑，在对电离辐射（IR）诱导的DNA损伤的适当反应中起重要作用。在此，我们研究了p300组蛋白乙酰转移酶的选择性小分子抑制剂C646的放射增敏作用，并探讨了其潜在机制。
通过克隆形成存活试验评估A549、H157和H460人非小细胞肺癌（NSCLC）细胞以及HFL-III人肺成纤维细胞。通过膜联蛋白V染色评估细胞凋亡和坏死。通过衰老相关β-半乳糖苷酶染色评估衰老。通过用DAPI染色评估核形态来评估有丝分裂灾难。通过流式细胞术分析细胞周期分布。通过免疫印迹分析蛋白质表达。
C646使A549、H460和H157细胞对IR敏感，在10%存活分数下的剂量增强比分别为1.4、1.2和1.2。C646未使HFL-III细胞放射增敏。在A549细胞中，但不在HFL-III细胞中，C646（i）增强IR后的有丝分裂灾难，但不增强细胞凋亡、坏死或衰老；（ii）增加IR后的超倍体细胞群体；（iii）抑制IR后CHK1的磷酸化。
C646通过消除G2期检查点维持来增强有丝分裂灾难，从而使NSCLC细胞放射增敏。
