1.
Manganese Oxide Nanoparticles As MRI Contrast Agents In Tumor Multimodal Imaging And Therapy.
Cai, X, Zhu, Q, Zeng, Y, Zeng, Q, Chen, X, Zhan, Y
International journal of nanomedicine. 2019;:8321-8344
Abstract
Contrast agents (CAs) play a crucial role in high-quality magnetic resonance imaging (MRI) applications. At present, as a result of the Gd-based CAs which are associated with renal fibrosis as well as the inherent dark imaging characteristics of superparamagnetic iron oxide nanoparticles, Mn-based CAs which have a good biocompatibility and bright images are considered ideal for MRI. In addition, manganese oxide nanoparticles (MONs, such as MnO, MnO2, Mn3O4, and MnOx) have attracted attention as T1-weighted magnetic resonance CAs due to the short circulation time of Mn(II) ion chelate and the size-controlled circulation time of colloidal nanoparticles. In this review, recent advances in the use of MONs as MRI contrast agents for tumor detection and diagnosis are reported, as are the advances in in vivo toxicity, distribution and tumor microenvironment-responsive enhanced tumor chemotherapy and radiotherapy as well as photothermal and photodynamic therapies.
2.
Downregulation of the c-MYC target gene, peroxiredoxin III, contributes to arsenic trioxide-induced apoptosis in acute promyelocytic leukemia.
Vivas-Mejía, PE, Ozpolat, B, Chen, X, Lopez-Berestein, G
International journal of cancer. 2009;(2):264-75
Abstract
Arsenic trioxide (ATO) induces differentiation and apoptosis in acute promyelocytic leukemia (APL). Several reports indicate that in APL cells apoptosis occurs mainly by a mechanism that involves the inhibition of glutathione peroxidase, one of the enzymes that regulates mitochondrial levels of H(2)O(2). Peroxiredoxin (Prx) III, a c-MYC target gene, is also a mitochondria-specific H(2)O(2)-scavenger enzyme. We studied here the role of Prx III during ATO-induced apoptosis in APL-derived NB4 cells, since these cells express high levels of Prx III. The protein and mRNA levels of Prx III decreased during ATO-induced apoptosis of NB4 cells. The downregulation of Prx III occurred before reactive oxygen species accumulation, reduction in the mitochondrial membrane potential and apoptosis. Depletion of Prx III enhanced mitochondrial-dependent apoptosis events. In contrast, overexpression of Prx III led to reduced levels of ATO-induced apoptosis. c-MYC was also downregulated in ATO-treated NB4 cells. Furthermore, depletion of c-MYC also reduced the Prx-III expression levels. Finally chromatin immunoprecipitation and luciferase reporter assays confirmed that downregulation of Prx-III was caused by the reduction of c-MYC levels during ATO-induced apoptosis of NB4 cells. These findings demonstrate a novel apoptotic-response pathway whereby downregulation of Prx-III potentiates ATO-induced apoptosis in APL cells.