Loratadine dysregulates cell cycle progression and enhances the effect of radiation in human tumor cell lines.
Loratadine dysregulates cell cycle progression and enhances the effect of radiation in human tumor cell lines.
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DOI：
10.1186/1748-717x-5-8
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发表时间：
2010-02-03
期刊：
影响因子：
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通讯作者：
Mitchell JB
中科院分区：
文献类型：
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作者：
Soule BP;Simone NL;DeGraff WG;Choudhuri R;Cook JA;Mitchell JB
组胺受体-1（H1）拮抗剂氯雷他定已被证明可抑制人结肠癌异种移植物的生长，部分原因是细胞周期停滞在G2/M期。由于这是细胞周期的辐射敏感期，我们试图确定氯雷他定是否改变了几种人类肿瘤细胞系的辐射敏感性，重点是人类结肠癌（HT 29）。在暴露于辐射之前和之后的几个时间点用几个剂量的氯雷他定处理细胞。使用全辐射剂量反应存活曲线测定辐射剂量修正因子（DMF）。流式细胞仪检测细胞周期，Western blot检测细胞周期相关蛋白Chk 1、pChk 1 ser 345和Cyclin B的表达。氯雷他定预处理指数生长的细胞（75 μM，24小时）增加了辐射诱导的细胞毒性，产生的辐射DMF为1.95。然而，平台期细胞的治疗也产生了DMF为1.3，表明细胞周期阻滞以外的机制也有助于氯雷他定介导的辐射修饰。与辐射一样，氯雷他定最初诱导G2/M期阻滞和细胞周期相关蛋白Chk 1活化为pChk 1 ser 345，然而随后总Chk 1和细胞周期蛋白B表达的降低与G2/M期检查点的取消相关。DNA修复酶表达和DNA片段化的分析显示，除了增强辐射诱导的损伤外，氯雷他定处理的细胞中还存在不同的DNA损伤模式。综上所述，这些数据表明，所观察到的氯雷他定的作用是多因素的，因为氯雷他定1）直接损伤DNA，2）激活Chk 1，从而促进G2/M期阻滞，使细胞对辐射诱导的DNA损伤更敏感，3）下调总Chk 1和细胞周期蛋白B，消除辐射诱导的G2/M检查点，使细胞重新进入细胞周期，尽管受损的DNA持续存在。鉴于这种独特的可能作用机制，氯雷他定有潜力作为化疗药物和癌症治疗中的放射反应调节剂，因此，可能需要进一步的临床评价。
The histamine receptor-1 (H1)-antagonist, loratadine has been shown to inhibit growth of human colon cancer xenografts in part due to cell cycle arrest in G2/M. Since this is a radiation sensitive phase of the cell cycle, we sought to determine if loratadine modifies radiosensitivity in several human tumor cell lines with emphasis on human colon carcinoma (HT29). Cells were treated with several doses of loratadine at several time points before and after exposure to radiation. Radiation dose modifying factors (DMF) were determined using full radiation dose response survival curves. Cell cycle phase was determined by flow cytometry and the expression of the cell cycle-associated proteins Chk1, pChk1ser345, and Cyclin B was analyzed by western blot. Loratadine pre-treatment of exponentially growing cells (75 μM, 24 hours) increased radiation-induced cytotoxicity yielding a radiation DMF of 1.95. However, treatment of plateau phase cells also yielded a DMF of 1.3 suggesting that mechanisms other than cell cycle arrest also contribute to loratadine-mediated radiation modification. Like irradiation, loratadine initially induced G2/M arrest and activation of the cell-cycle associated protein Chk1 to pChk1ser345, however a subsequent decrease in expression of total Chk1 and Cyclin B correlated with abrogation of the G2/M checkpoint. Analysis of DNA repair enzyme expression and DNA fragmentation revealed a distinct pattern of DNA damage in loratadine-treated cells in addition to enhanced radiation-induced damage. Taken together, these data suggest that the observed effects of loratadine are multifactorial in that loratadine 1) directly damages DNA, 2) activates Chk1 thereby promoting G2/M arrest making cells more susceptible to radiation-induced DNA damage and, 3) downregulates total Chk1 and Cyclin B abrogating the radiation-induced G2/M checkpoint and allowing cells to re-enter the cell cycle despite the persistence of damaged DNA. Given this unique possible mechanism of action, loratadine has potential as a chemotherapeutic agent and as a modifier of radiation responsiveness in the treatment of cancer and, as such, may warrant further clinical evaluation.