Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada.
PLoS One. 2013 Sep 30;8(9):e75446. doi: 10.1371/journal.pone.0075446. eCollection 2013.
Drug resistance, absence of an effective vaccine, and inadequate public health measures are major impediments to controlling Plasmodium falciparum malaria worldwide. The development of antimalarials to which resistance is less likely is paramount. To this end, we have exploited the chaperone function of P. falciparum Hsp90 (PfHsp90) that serves to facilitate the expression of resistance determinants.
The affinity and activity of a purine analogue Hsp90 inhibitor (PU-H71) on PfHsp90 was determined using surface plasmon resonance (SPR) studies and an ATPase activity assay, respectively. In vitro, antimalarial activity was quantified using flow cytometry. Interactors of PfHsp90 were determined by LC-MS/MS. In vivo studies were conducted using the Plasmodium berghei infection mouse model.
PU-H71 exhibited antimalarial activity in the nanomolar range, displayed synergistic activity with chloroquine in vitro. Affinity studies reveal that the PfHsp90 interacts either directly or indirectly with the P. falciparum chloroquine resistance transporter (PfCRT) responsible for chloroquine resistance. PU-H71 synergized with chloroquine in the P.berghei mouse model of malaria to reduce parasitemia and improve survival.
We propose that the interaction of PfHsp90 with PfCRT may account for the observed antimalarial synergy and that PU-H71 is an effective adjunct for combination therapy.
耐药性、缺乏有效疫苗以及公共卫生措施不足是全球控制恶性疟原虫疟疾的主要障碍。开发不太可能产生耐药性的抗疟药物至关重要。为此，我们利用了恶性疟原虫热休克蛋白 90（PfHsp90）的伴侣功能，该功能有助于表达耐药决定因素。
使用表面等离子体共振（SPR）研究和 ATP 酶活性测定分别确定嘌呤类似物 Hsp90 抑制剂（PU-H71）对 PfHsp90 的亲和力和活性。在体外，使用流式细胞术定量抗疟活性。通过 LC-MS/MS 确定 PfHsp90 的相互作用物。在体内研究中，使用伯氏疟原虫感染小鼠模型进行。
PU-H71 在纳摩尔范围内表现出抗疟活性，在体外与氯喹表现出协同活性。亲和研究表明，PfHsp90 直接或间接地与负责氯喹耐药的恶性疟原虫氯喹耐药转运蛋白（PfCRT）相互作用。在伯氏疟原虫感染小鼠模型中，PU-H71 与氯喹协同作用可降低寄生虫血症并提高存活率。
我们提出 PfHsp90 与 PfCRT 的相互作用可能解释了观察到的抗疟协同作用，并且 PU-H71 是联合治疗的有效辅助药物。
