title: Alkylation of phosphorothioated thrombin binding aptamers improves the selectivity of inhibition of tumor cell proliferation upon anticoagulation.
abstract: Recently, aptamers have been extensively researched for therapy and diagnostic applications. Thrombin-binding aptamer is a 15nt deoxyribonucleic acid screened by SELEX, it can specifically bind to thrombin and inhibit blood coagulation. Since it is also endowed with excellent antitumor activity, the intrinsic anticoagulation advantage converted to a main potential side effect for its further application in antiproliferative therapy.
  
  
  
  Site-specific alkylation was conducted through nucleophilic reaction of phosphorothioated TBAs using bromide reagents. Circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR) measurements were used to evaluate anticoagulation activity, and a CCK-8 assay was used to determine cell proliferation activity.
  
  
  
  The CD spectra of the modified TBAs were weakened, and their affinity for thrombin was dramatically reduced, as reflected by the KDvalues. On the other hand, their inhibition of A549 cells was retained.
  
  
  
  Incorporation of different alkyls apparently disrupted the binding of TBA to thrombin while maintaining the antitumor activity.
  
  
  
  A new modification strategy was established for the use of TBA as a more selective antitumor agent.
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
authors.forename: Xiantao
authors.initials: X
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
authors.forename: Yuejie
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Guan
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
authors.forename: Lihe
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China. Electronic address: yangzj@bjmu.edu.cn.
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000478:Alkylation; D000925:Anticoagulants / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D052157:Aptamers, Nucleotide / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism; D006801:Humans; D020349:Surface Plasmon Resonance; D013917:Thrombin / Q000378:metabolism*
chemical_list: D000925:Anticoagulants; D000970:Antineoplastic Agents; D052157:Aptamers, Nucleotide; C081676:thrombin aptamer; D013917:Thrombin
keywords: Alkylation; Antitumor; Selectivity; Thrombin binding aptamer