DNA modifications by a novel bifunctional trinuclear platinum Phase I anticancer agent
DNA modifications by a novel bifunctional trinuclear platinum Phase I anticancer agent
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DOI：
10.1021/bi990124s
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发表时间：
1999-05-25
期刊：
影响因子：
2.9
通讯作者：
Farrell, N
中科院分区：
文献类型：
--
作者：
Brabec, V;Kaspárková, J;Farrell, N
一种新的，三核铂I期临床药物（BBR 3464）的DNA结合概况进行了总结。BBR 3464的结构最好描述为通过四胺[trans-Pt（NH3）（2）{H2N（CH2）（6）NH2}（2）]（2+）单元连接的两个反式-[PtCl（NH3）（2）]单元。BBR 3464的+4电荷、至少两个能够与DNA结合的Pt配位单元的存在以及这种DNA结合的后果是与顺铂结构范例的显著偏离。化学和生物学特征表明，该药物应被认为是一种全新结构的DNA修饰抗癌剂的第一个临床代表。BBR 3464上的高电荷促进与DNA的快速结合，t（1/2）类似于40分钟，显著快于中性顺铂。BBR 3464加合DNA的解链温度在低离子强度下升高，而在高盐浓度下降低。这种不寻常的行为与顺铂相反。BBR 3464在负超螺旋pSP73质粒DNA中产生14度的解旋角，表明双功能DNA结合。用EcoRI线性化的质粒pSP73 DNA中链间DNA-DNA交联的定量表明约20%的DNA是链间交联的。虽然这显著高于顺铂的值，但有趣的是，它低于双核铂化合物如[{trans-PtCl（NH3）（2）}（2）H2N（CH2）（6）NH2]（2+）（BBR 3005）的值，其中链间交联效率可高达70 - 90%。接头骨架中电荷的存在或铂化部分之间距离的增加可能导致BBR 3464诱导DNA链间交联的能力相对降低。溴化乙锭的荧光实验与BBR 3464产生的DNA上的长程离域损伤的形成一致。通过用Vent（R）（exo（+））DNA聚合酶测定多核苷酸的延伸，确定质粒DNA上BBR 3464的序列偏好为精确的碱基对。强烈的序列偏好的单一dG或d（GG）的网站建议。与顺铂或BBR 3005相比，DNA上存在相对较少的阻断，表明序列选择性高。选择以下发生终止位点的适当顺序：2019 - 05 - 25 00：00：00 00：00 00：00 00：00 00：00 00：00 00 033）T'（34）C'（35）G'（36）G'（37）T'（38）A'（39）3'-A（23）C-24 T-25 T-26 A（27）A（28）G（29）C-33 0 T-31 C-32 G（33）A（34）G（35）C-36 C-37 A（38）T-39 1，4链间分子建模（G ′（30）至G（33））和1，5链内（G（33）至G（29））交联进一步证实了两种交联形式之间能量的相似性。最后，免疫化学分析证实了BBR 3464形成的DNA加合物的独特性质。该分析表明，针对顺铂加合DNA产生的抗体不识别BBR 3464修饰的DNA。相反，BBR 3464修饰的DNA抑制了抗体与transplatin-adducted DNA的结合。因此，BBR 3464的双功能结合与顺铂几乎没有相似之处，但可能具有被认为与transplatinum物质相似的加合物子集。总之，结果指出BBR 3464的DNA结合的独特特征，加强了最初的假设，即以不同于顺铂的方式修饰DNA结合也将导致独特的抗肿瘤活性特征。
The DNA-binding profile of a novel, trinuclear platinum Phase I clinical agent (BBR3464) is summarized. The structure of BBR3464 is best described as two trans-[PtCl(NH3)(2)] units linked by a tetra-amine [trans-Pt(NH3)(2){H2N(CH2)(6)NH2}(2)](2+) unit. The +4 charge of BBR3464, the presence of at least two Pt coordination units capable of binding to DNA, and the consequences of such DNA binding are remarkable departures from the cisplatin structural paradigm. The chemical and biological features argue that the drug should be considered the first clinical representative of an entirely new structural class of DNA-modifying anticancer agents. The high charge on BBR3464 facilitates rapid binding to DNA with a t(1/2) of similar to 40 min, significantly faster than the neutral cisplatin. The melting temperature of DNA adducted by BBR3464 increased at low ionic strength but decreased in high salt for the same rb. This unusual behavior is in contrast to that of cisplatin. BBR3464 produces an unwinding angle of 14 degrees in negatively supercoiled pSP73 plasmid DNA, indicative of bifunctional DNA binding. Quantitation of interstrand DNA-DNA cross-linking in plasmid pSP73 DNA linearized by EcoRI indicated approximately 20% of the DNA to be interstrand cross-linked. While this is significantly higher than the value for cisplatin, it is, interestingly, lower than that for dinuclear platinum compounds such as [{trans-PtCl(NH3)(2)}(2)H2N(CH2)(6)NH2](2+) (BBR3005) where interstrand cross-linking efficiency may be as high as 70-90%. Either the presence of charge in the linker backbone or the increased distance between platinating moieties may contribute to this relatively decreased ability of BBR3464 to induce DNA interstrand cross-linking. Fluorescence experiments with ethidium bromide were consistent with the formation of long-range delocalized lesions on DNA produced by BBR3464. The sequence preference for BBR3464 on plasmid DNA was determined to the exact base pair by assaying extension of the polynucleotide by Vent(R)(exo(+)) DNA polymerase. Strong sequence preference for single dG or d(GG) sites was suggested. The presence of relatively few blocks on DNA in comparison to either cisplatin or BBR3005 was indicative of high sequence selectivity. The following appropriate sequence where stop sites occur was chosen:5'-T'(23) G'(24) A'(25) A'(26) T'(27) T'(28) C'(29) G'(30) A'(31) G'(32) C'(33) T'(34) C'(35) G'(36) G'(37) T'(38) A'(39) 3'- A(23) C-24 T-25 T-26 A(27) A(28) G(29) C-30 T-31 C-32 G(33) A(34) G(35) C-36 C-37 A(38) T-39molecular modeling on 1,4 interstrand (G'(30) to G(33)) and 1,5 intrastrand (G(33) to G(29)) cross-links further confirmed the similarity in energy between the two forms of cross-link. Finally, immunochemical analysis confirmed the unique nature of the DNA adducts formed by BBR3464. This analysis showed that antibodies raised to cisplatin-adducted DNA did not recognize DNA modified by BBR3464. In contrast, DNA modified by BBR3464 inhibited the binding of antibodies raised to transplatin-adducted DNA. Thus, the bifunctional binding of BBR3464 contains few similarities to that of cisplatin but may have a subset of adducts recognized as being similar to the transplatinum species. In summary, the results point to a unique profile of DNA binding for BBR3464, strengthening the originial hypothesis that modification of DNA binding in manners distinct from that of cisplatin will also lead to a distinct and unique profile of antitumor activity.