USP7-mediated ERß stabilization mitigates ROS accumulation and promotes osimertinib resistance by suppressing PRDX3 SUMOylation in non-small cell lung carcinoma.

Osimertinib resistance is regarded as a major obstacle limiting survival benefits for patients undergoing treatment of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC). However, the underlying mechanisms of acquired resistance remain unclear. In this study, we report that estrogen receptor ß (ERß) is highly expressed in osimertinib-resistant NSCLC and plays a pivotal role in promoting osimertinib resistance. We further identified ubiquitin-specific protease 7 (USP7) as a critical binding partner that deubiquitinates and upregulates ERß in NSCLC. ERß promotes osimertinib resistance by mitigating reactive oxygen species (ROS) accumulation. We found that ERß mechanistically suppresses peroxiredoxin 3 (PRDX3) SUMOylation and thus confers osimertinib resistance onto NSCLC. Furthermore, we provide evidence showing that depletion of ERß induces ROS accumulation and reverses osimertinib resistance in NSCLC both in vitro and in vivo. Thus, our results demonstrate that USP7-mediated ERß stabilization suppresses PRDX3 SUMOylation to mitigate ROS accumulation and promote osimertinib resistance, suggesting that targeting ERß may be an effective therapeutic strategy to overcome osimertinib resistance in NSCLC.

Structural New Data for Mitochondrial Peroxiredoxin From Trypanosoma cruzi Show High Similarity With Human Peroxiredoxin 3: Repositioning Thiostrepton as Antichagasic Drug.

Trypanosoma cruzi, the causal agent of Chagas disease, has peroxiredoxins (PRXs) expressed in all stages of the parasite and whose function is to detoxify oxidizing agents, such as reactive oxygen species (ROS). These proteins are central for the survival and replication of the parasite and have been proposed as virulence factors. Because of their importance, they have also been considered as possible therapeutic targets, although there is no specific drug against them. One of them, the mitochondrial PRX (TcMPX), is important in the detoxification of ROS in this organelle and has a role in the infectivity of T. cruzi. However, their structural characteristics are unknown, and possible inhibitors have not been proposed. The aim was to describe in detail some structural characteristics of TcMPX and compare it with several PRXs to find possible similarities and repositioning the antibiotic Thiostrepton as a potential inhibitor molecule. It was found that, in addition to the characteristic active site of a 2-cys PRX, this protein has a possible transmembrane motif and motifs involved in resistance to hyper oxidation. The homology model suggests a high structural similarity with human PRX3. This similarity was corroborated by cross-recognition using an anti-human PRX antibody. In addition, molecular docking showed that Thiostrepton, a potent inhibitor of human PRX3, could bind to TcMPX and affect its function. Our results show that Thiostrepton reduces the proliferation of T. cruzi epimastigotes, cell-derived trypomastigotes, and blood trypomastigotes with low cytotoxicity on Vero cells. We also demonstrated a synergic effect of Thriostepton and Beznidazol. The convenience of seeking treatment alternatives against T. cruzi by repositioning compounds as Thiostrepton is discussed.

Peroxiredoxin III Protects Tumor Suppressor PTEN from Oxidation by 15-Hydroperoxy-eicosatetraenoic Acid.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid and protein phosphatase that coordinates various cellular processes. Its activity is regulated by the reversible oxidation of an active-site cysteine residue by H2O2 and thioredoxin. However, the potential role of lipid peroxides in the redox regulation of PTEN remains obscure. To evaluate this, 15-hydroperoxy-eicosatetraenoic acid (15s-HpETE), a lipid peroxide, was employed to investigate its effect on PTEN using molecular and cellular-based assays. Exposure to 15s-HpETE resulted in the oxidation of recombinant PTEN. Reversible oxidation of PTEN was also observed in mouse embryonic fibroblast (MEF) cells treated with a 15s-HpETE and Lipofectamine mixture. The oxidative dimerization of thioredoxin was found simultaneously. In addition, the absence of peroxiredoxin III aggravated 15s-HpETE-induced PTEN oxidation in MEF cells. Our study provides novel insight into the mechanism linking lipid peroxidation to the etiology of tumorigenesis.

Peroxiredoxin 3 promotes IL-12 production from macrophages and partially protects mice against infection with Toxoplasma gondii.

Toxoplasmosis remains a life-threatening infection of humans and various domestic and wild animals worldwide. It is caused by the obligatory intracellular protozoan parasite Toxoplasma gondii. Peroxiredoxins (Prxs) are a family of antioxidant enzymes that protect cells from oxidative stress from hydroperoxides. In the recent years, several studies have reported the potential use of T. gondii-derived enzymes in triggering protective immunity against T. gondii infection. Therefore, this study was conducted to investigate the immunogenicity and protective efficacy of TgPrx3. In vitro stimulation of peritoneal macrophages with recombinant TgPrx3 protein fused to glutathione-S transferase (TgPrx3-GST) enhanced IL-12p40 production, indicating the immune-stimulating potentials of TgPrx3. Next, protective efficacy was investigated by subcutaneous inoculation of mice with TgPrx3-GST (25pmol), and recombinant GST or PBS were used as the controls. Mice immunized with TgPrx3-GST exhibited a significant elevation of specific antibodies in terms of IgG1 and IgG2c isotypes. Moreover, interferon-gamma production and spleen cell proliferation dramatically increased in the TgPrx3-GST-sensitized cells from mice immunized with the same antigen. The severity of the T. gondii infections tended to be attenuated in the TgPrx3-GST-immunized mice, as evidenced by their higher survival rates and lower parasite burdens in the brain. Altogether, TgPrx3 immunization induced specific humoral and cellular immune responses and partially protected the mice against lethal toxoplasmosis. Our results suggest the possible use of TgPrx3 as a vaccine candidate against T. gondii infections.