Federici Luca, Lo Sterzo Carlo, Pezzola Silvia, Di Matteo Adele, Scaloni Flavio, Federici Giorgio, Caccuri Anna Maria
Department of Biomedical Sciences, University of Chieti, CeSI Center of Excellence on Aging, G D'Annunzio University Foundation, Chieti, Italy.
Cancer Res. 2009 Oct 15;69(20):8025-34. doi: 10.1158/0008-5472.CAN-09-1314. Epub 2009 Oct 6.
Glutathione S-transferases (GST) constitute a superfamily of enzymes with diversified functions including detoxification from xenobiotics. In many human cancers, Pi class GST (GSTP1-1) is overexpressed and contributes to multidrug resistance by conjugating chemotherapeutics. In addition, GSTP1-1 displays antiapoptotic activity by interacting with c-Jun NH(2)-terminal kinase, a key regulator of apoptosis. Therefore, GSTP1-1 is considered a promising target for pharmaceutical treatment. Recently, a potent inhibitor of GSTs, 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX), was identified and tested on several tumor cell lines demonstrating high antiproliferative activity. To establish the structural basis of NBDHEX activity, we determined the crystal structure of NBDHEX bound to either GSTP1-1 or GSTM2-2 (mu class). NBDHEX in both cases binds to the H-site but occupies different positions. Furthermore, the compound is covalently attached to the GSH sulfur in the GSTM2-2 crystal, forming a sigma-complex, although it is bound but not conjugated in the GSTP1-1 crystal. Several differences in the H-sites of the two isozymes determine the higher affinity of NBDHEX for GSTM2-2 with respect to GSTP1-1. One such difference is the presence of Ile(104) in GSTP1-1 close to the bound NBDHEX, whereas the corresponding position is occupied by an alanine in GSTM2-2. Mutation of Ile(104) into valine is a frequent GSTP1-1 polymorphism and we show here that the Ile(104)Val and Ile(104)Ala variants display a 4-fold higher affinity for the compound. Remarkably, the GSTP1-1/Ile(104)Ala structure in complex with NBDHEX shows a considerable shift of the compound inside the H-site. These data might be useful for the development of new anticancer compounds.
谷胱甘肽S-转移酶（GST）构成了一个具有多种功能的酶超家族，包括对外源生物的解毒作用。在许多人类癌症中，Pi类GST（GSTP1-1）过度表达，并通过结合化疗药物导致多药耐药。此外，GSTP1-1通过与凋亡的关键调节因子c-Jun NH(2)-末端激酶相互作用而表现出抗凋亡活性。因此，GSTP1-1被认为是药物治疗的一个有前景的靶点。最近，一种有效的GST抑制剂6-(7-硝基-2,1,3-苯并恶二唑-4-基硫代)己醇（NBDHEX）被鉴定出来，并在几种肿瘤细胞系上进行了测试，显示出高抗增殖活性。为了确定NBDHEX活性的结构基础，我们测定了与GSTP1-1或GSTM2-2（μ类）结合的NBDHEX的晶体结构。在这两种情况下，NBDHEX都与H位点结合，但占据不同的位置。此外，该化合物在GSTM2-2晶体中与谷胱甘肽硫共价结合，形成一个σ-复合物，尽管它在GSTP1-1晶体中是结合但未共轭的。两种同工酶的H位点的几个差异决定了NBDHEX对GSTM2-2相对于GSTP1-1具有更高的亲和力。其中一个差异是GSTP1-1中靠近结合的NBDHEX处存在Ile(104)，而在GSTM2-2中相应位置被丙氨酸占据。Ile(104)突变为缬氨酸是一种常见的GSTP1-1多态性，我们在此表明Ile(104)Val和Ile(104)Ala变体对该化合物的亲和力高4倍。值得注意的是，与NBDHEX复合的GSTP1-1/Ile(104)Ala结构显示该化合物在H位点内有相当大的位移。这些数据可能有助于开发新的抗癌化合物。
