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The vulnerability of some cancer cells to oxidative signals is a therapeutic target for the rational design of new anticancer agents. In addition to their well characterized effects on cell division, many cytotoxic anticancer agents can induce oxidative stress by modulating levels of reactive oxygen species (ROS) such as the superoxide anion radical, hydrogen peroxide and hydroxyl radicals. Tumour cells are particularly sensitive to oxidative stress as they typically have persistently higher levels of ROS than normal cells due to the dysregulation of redox balance that develops in cancer cells in response to increased intracellular production of ROS or depletion of antioxidant proteins. In addition, excess ROS levels potentially contribute to oncogenesis by the mediation of oxidative DNA damage. There are several anticancer agents in development that target cellular redox regulation. The overall cellular redox state is regulated by three systems that modulate cellular redox status by counteracting free radicals and ROS, or by reversing the formation of disulfides; two of these are dependent on glutathione and the third on thioredoxin. Drugs targeting S -glutathionylation have direct anticancer effects via cell signalling pathways and inhibition of DNA repair, and have an impact on a wide range of signalling pathways. Of these agents, NOV-002 and canfosfamide have been assessed in phase III trials, while a number of others are undergoing evaluation in early phase clinical trials. Alternatively, agents including PX-12, dimesna and motexafin gadolinium are being developed to target thioredoxin, which is overexpressed in many human tumours, and this overexpression is associated with aggressive tumour growth and poorer clinical outcomes. Finally, arsenic derivatives have demonstrated antitumour activity including antiproliferative and apoptogenic effects on cancer cells by pro-oxidant mechanisms, and the induction of high levels of oxidative stress and apoptosis by an as yet undefined mechanism. In this article we review anticancer drugs currently in development that target cellular redox activity to treat cancer.

Fifty percent of male subfertility diagnosis is idiopathic and is usually associated with genetic abnormalities or protein dysfunction, which are not detectable through the conventional spermiogram. Glutathione S -transferases (GSTs) are antioxidant enzymes essential for preserving sperm function and maintaining fertilizing ability. However, while the role of GSTP1 in cell signaling regulation via the inhibition of c-Jun N-terminal kinases (JNK) has been enlightened in somatic cells, it has never been investigated in mammalian spermatozoa. In this regard, a comprehensive approach through immunoblotting, immunofluorescence, computer-assisted sperm assessment (CASA), and flow cytometry analysis was used to characterize the molecular role of the GSTP1–JNK heterocomplex in sperm physiology, using the pig as a model. Immunological assessments confirmed the presence and localization of GSTP1 in sperm cells. The pharmacological dissociation of the GSTP1–JNK heterocomplex resulted in the activation of JNK, which led to a significant decrease in sperm viability, motility, mitochondrial activity, and plasma membrane stability, as well as to an increase of intracellular superoxides. No effects in intracellular calcium levels and acrosome membrane integrity were observed. In conclusion, the present work has demonstrated, for the first time, the essential role of GSTP1 in deactivating JNK, which is crucial to maintain sperm function and has also set the grounds to understand the relevance of the GSTP1–JNK heterocomplex for the regulation of mammalian sperm physiology.

Background TFE3-translocation renal cell carcinoma (TFE3-tRCC), a distinct subtype of kidney cancer characterized by Xp11.2 translocations, involving TFE3 fusion with various partner genes, lacks effective treatments and prognostic biomarkers for advanced stages. This study aimed to unravel the pathogenic mechanisms and uncover novel therapeutic targets. Methods The transcriptional characterization of TFE3-tRCC was conducted by RNA sequencing on 14 untreated primary TFE3-tRCC patients. The relative mRNA and protein levels were detected using qRT-PCR and Western blot, respectively. The location of ASPL-TFE3 fusion protein was analyzed by immunofluorescence. MTT and colony formation assays were used to detect cell proliferation. Annexin V/PI staining was used to evaluate cell apoptosis. Transwell assays were used to evaluate in vitro cell migration and invasion. Results In TFE3-tRCC patients, GSTP1 expression was upregulated. ASPL-TFE3 cell models revealed that the ASPL-TFE3 fusion protein translocates to the nucleus, contributing to tumorigenesis. Notably, GSTP1 was transcriptionally activated by chimeric TFE3. Treatment with GSTP1-targeting siRNA or the GSTP1 inhibitor Ezatiostat effectively inhibited tumor growth and induced apoptosis in TFE3-tRCC cells. Furthermore, GSTP1 was found to drive TFE3-tRCC progression via modulation of the JNK signaling pathway. Conclusion Upregulation of GSTP1 mediated by chimeric TFE3 promotes TFE3-tRCC progression by targeting JNK signaling pathway, which underscore the potential of GSTP1 as a promising therapeutic target for TFE3-tRCC.

Idiopathic chronic neutropenia (ICN) describes a heterogeneous group of hematologic diseases characterized by low circulating neutrophil levels often associated with recurrent fevers, chronic mucosal inflammation, and severe systemic infections. The severity and risk of complications, including serious infections, are inversely proportional to the absolute neutrophil count (ANC), with the greatest problems occurring in patients with an ANC of less than 0.5 × 10 9 /L. This case report describes a 64-year-old female with longstanding rheumatoid arthritis who subsequently developed ICN with frequent episodes of sepsis requiring hospitalization and prolonged courses of antibiotics over a 4-year period. She was treated with granulocyte colony stimulating factors (G-CSF) but had a delayed, highly variable, and volatile response. She was enrolled in a clinical trial evaluating the oral investigational agent ezatiostat. Ezatiostat, a glutathione S-transferase P1-1 inhibitor, activates Jun kinase, promoting the growth and maturation of hematopoietic progenitor stem cells. She responded by the end of the first month of treatment with stabilization of her ANC (despite tapering and then stopping G-CSF), clearing of fever, and healing of areas of infection. This ANC response to ezatiostat treatment has now been sustained for over 8 months and continues. These results suggest potential roles for ezatiostat in the treatment of patients with ICN who are not responsive to G-CSF, as an oral therapy alternative, or as an adjunct to G-CSF, and further studies are warranted.

Background Ezatiostat, a glutathione S-transferase P1-1 inhibitor, promotes the maturation of hematopoietic progenitors and induces apoptosis in cancer cells. Results Ezatiostat was administered to 19 patients with non-deletion(5q) myelodysplastic syndrome (MDS) at one of two doses (2000 mg or 2500 mg/day) in combination with 10 mg of lenalidomide on days 1–21 of a 28-day cycle. No unexpected toxicities occurred and the incidence and severity of adverse events (AEs) were consistent with that expected for each drug alone. The most common non-hematologic AEs related to ezatiostat in combination with lenalidomide were mostly grade 1 and 2 fatigue, anorexia, nausea, diarrhea, and vomiting; hematologic AEs due to lenalidomide were thrombocytopenia, neutropenia, and anemia. One of 4 evaluable patients (25%) in the 2500/10 mg dose group experienced an erythroid hematologic improvement (HI-E) response by 2006 MDS International Working Group (IWG) criteria. Four of 10 evaluable patients (40%) in the 2000 mg/10 mg dose group experienced an HI-E response. Three of 7 (43%) red blood cell (RBC) transfusion-dependent patients became RBC transfusion independent, including one patient for whom prior lenalidomide monotherapy was ineffective. Three of 5 (60%) thrombocytopenic patients had an HI-platelet (HI-P) response. Bilineage HI-E and HI-P responses occurred in 3 of 5 (60%), 1 of 3 with HI-E and HI-N (33%), and 1 of 3 with HI-N and HI-P (33%). One of 3 patients (33%) with pancytopenia experienced a complete trilineage response. All multilineage responses were observed in the 2000/10 mg doses recommended for future studies. Conclusions The tolerability and activity profile of ezatiostat co-administered with lenalidomide supports the further development of ezatiostat in combination with lenalidomide in MDS and also encourages studies of this combination in other hematologic malignancies where lenalidomide is active. Trial registration Clinicaltrials.gov: NCT01062152

Opinion statement The myelodysplastic syndromes (MDS) are a group of clonal hematopoietic disorders characterized by bone marrow failure and a risk of progression to acute myelogenous leukemia (AML). A precise diagnosis is critical, because there is overlap between the clinical and laboratory findings of MDS and other malignant and nonmalignant hematologic disorders. Several prognostic scoring systems (IPSS, WPSS, LR-PSS, and IPSS-R) assess a patient’s risk of progression to AML and overall survival. Many patients are elderly, so age and comorbidities are an important consideration. Patients with lower-risk disease are treated with growth factors (erythropoietin stimulating agents and/or G-CSF) and immunomodulatory agents (antithymocyte globulin and/or lenalidomide). Patients with higher-risk disease have a higher risk of progression to AML and are treated with hypomethylating agents (azacitidine or decitabine) and allogeneic stem cell transplantation if appropriate. Recent laboratory studies have increased our understanding of the pathophysiology of this disease. Mutations in genes effecting ribosomes, splicing of RNA and epigenetics have been discovered. It is likely that these breakthroughs will lead to newer classes of targeted therapies against this disease.