Panat Niranjan A, Singh Beena G, Maurya Dharmendra K, Sandur Santosh K, Ghaskadbi Saroj S
Department of Zoology, Savitribai Phule Pune University (SPPU), Pune, 411007, India; Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India.
Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India.
Chem Biol Interact. 2016 May 5;251:34-44. doi: 10.1016/j.cbi.2016.03.024. Epub 2016 Mar 22.
Troxerutin, a flavonoid best known for its radioprotective and antioxidant properties is of considerable interest of study due to its broad pharmacological activities. The present study on troxerutin highlights its abilities to bind DNA and enhance cancer cell killing in response to radiation. Troxerutin showed strong binding with calf thymus DNA in vitro. Troxerutin-DNA interaction was confirmed by CD spectropolarimetry. The mode of binding of troxerutin to DNA was assessed by competing troxerutin with EtBr or DAPI, known DNA intercalator and a minor groove binder, respectively. DAPI fluorescence was drastically reduced with linear increase in troxerutin concentration suggesting possible binding of troxerutin to DNA minor groove. Further, computational studies of docking of troxerutin molecule on mammalian DNA also indicated possible troxerutin-DNA interaction at minor groove of DNA. Troxerutin was found to mainly localize in the nucleus of prostate cancer cells. It induced cytotoxicity in radioresistant (DU145) and sensitive (PC3) prostate cancer cells. When troxerutin pre-treated DU145 and PC3 cells were exposed to γ-radiation, cytotoxicity as estimated by MTT assay, was found to be further enhanced. In addition, the % subG1 population detected by propidium iodide staining also showed similar response when combined with radiation. A similar trend was observed in terms of ROS generation and DNA damage in DU145 cells when troxerutin and radiation were combined. DNA binding at minor groove by troxerutin may have contributed to strand breaks leading to increased radiation induced cell death.
曲克芦丁是一种黄酮类化合物，以其辐射防护和抗氧化特性而闻名，由于其广泛的药理活性，具有相当大的研究价值。目前关于曲克芦丁的研究突出了其与DNA结合的能力以及增强辐射诱导癌细胞杀伤的能力。曲克芦丁在体外与小牛胸腺DNA表现出强烈的结合。通过圆二色光谱偏振法证实了曲克芦丁与DNA的相互作用。分别用已知的DNA嵌入剂溴化乙锭（EtBr）和小沟结合剂4',6-二脒基-2-苯基吲哚（DAPI）与曲克芦丁竞争，评估曲克芦丁与DNA的结合模式。随着曲克芦丁浓度线性增加，DAPI荧光急剧降低，表明曲克芦丁可能与DNA小沟结合。此外，曲克芦丁分子与哺乳动物DNA对接的计算研究也表明，在DNA小沟处可能存在曲克芦丁与DNA的相互作用。发现曲克芦丁主要定位于前列腺癌细胞的细胞核中。它在抗辐射（DU145）和敏感（PC3）前列腺癌细胞中诱导细胞毒性。当用曲克芦丁预处理的DU145和PC3细胞暴露于γ辐射时，通过MTT法估计的细胞毒性进一步增强。此外，用碘化丙啶染色检测到的亚G1期细胞百分比在与辐射联合时也表现出类似的反应。当曲克芦丁与辐射联合时，在DU145细胞中观察到活性氧生成和DNA损伤方面有类似趋势。曲克芦丁在小沟处与DNA的结合可能导致链断裂，从而导致辐射诱导的细胞死亡增加。
