Zinc transporter LIV1: A promising cell surface target for triple negative breast cancer.

Breast cancer is one of the leading causes contributing to the global cancer burden. The triple negative breast cancer (TNBC) molecular subtype accounts for the most aggressive type. Despite progression in therapeutic options and prognosis in breast cancer treatment options, there remains a high rate of distant relapse. With advancements in understanding the role of zinc and zinc carriers in the prognosis and treatment of the disease, the scope of precision treatment/targeted therapy has been expanded. Zinc levels and zinc transporters play a vital role in maintaining cellular homeostasis, tumor surveillance, apoptosis, and immune function. This review focuses on the zinc transporter, LIV1, as an essential target for breast cancer prognosis and emerging treatment options. Previous studies give an insight into the role of LIV1 in fulfilling the most important hallmarks of cancer such as apoptosis, metastasis, invasion, and evading the immune system. Normal tissue expression of LIV1 is limited. Higher expression of LIV1 has been linked to Epithelial-Mesenchymal Transition, histological grade of cancer, and early node metastasis. LIV1 was found to be one of the attractive targets in the therapeutic hunt for TNBCs. TNBCs are an immunogenic breast cancer subtype. As zinc transporters are known to serve as the metabolic gatekeepers of immune cells, this review bridges tumor infiltrating lymphocytes, TNBC and LIV1. In addition, the suitability of LIV1 as an antibody-drug conjugate (Seattle genetics [SGN]-LIV1A) target in TNBC, represents a promising strategy for patients. Early clinical trial results reveal that this novel agent reduces tumor burden by inducing mitotic arrest, immunomodulation, and immunogenic cell death, warranting further investigation of SGN-LIV1A in combination with immuno-oncology agents. Priming the patient's immune response in combination with SGN-LIV1A could eventually change the landscape for the TNBC patient population.

ZIP9 Is a Druggable Determinant of Sex Differences in Melanoma.

Melanoma and most other cancers occur more frequently and have worse prognosis in males compared with females. Although sex steroids are thought to be involved, classical androgen and estrogen receptors are not detectable in most melanomas. Here we show that testosterone promotes melanoma proliferation by activating ZIP9 (SLC39A9), a zinc transporter that is widely expressed in human melanoma but not intentionally targeted by available therapeutics. This testosterone activity required an influx of zinc, activation of MAPK, and nuclear translocation of YAP. FDA-approved inhibitors of the classical androgen receptor also inhibited ZIP9, thereby antagonizing the protumorigenic effects of testosterone in melanoma. In male mice, androgen receptor inhibitors suppressed growth of ZIP9-expressing melanomas but had no effect on isogenic melanomas lacking ZIP9 or on melanomas in females. These data suggest that ZIP9 might be effectively targeted in melanoma and other cancers by repurposing androgen receptor inhibitors that are currently approved only for prostate cancer. SIGNIFICANCE: Testosterone signaling through ZIP9 mediates some of the sex differences in melanoma, and drugs that target AR can be repurposed to block ZIP9 and inhibit melanoma in males.

Gene interfered-ferroptosis therapy for cancers.

Although some effective therapies have been available for cancer, it still poses a great threat to human health and life due to its drug resistance and low response in patients. Here, we develop a ferroptosis-based therapy by combining iron nanoparticles and cancer-specific gene interference. The expression of two iron metabolic genes (FPN and LCN2) was selectively knocked down in cancer cells by Cas13a or microRNA controlled by a NF-κB-specific promoter. Cells were simultaneously treated by iron nanoparticles. As a result, a significant ferroptosis was induced in a wide variety of cancer cells. However, the same treatment had little effect on normal cells. By transferring genes with adeno-associated virus and iron nanoparticles, the significant tumor growth inhibition and durable cure were obtained in mice with the therapy. In this work, we thus show a cancer therapy based on gene interference-enhanced ferroptosis.

MicroRNA-302a-3p induces ferroptosis of non-small cell lung cancer cells via targeting ferroportin.

Ferroptosis is a newly described regulated form of cell death that contributes to the progression of non-small cell lung cancers (NSCLCs). MicroRNA-302a-3p (miR-302a-3p) plays critical roles in the tumorigenicity of different cancers; however, its function and underlying mechanism in ferroptosis and NSCLCs remain unclear. Human NSCLCs cells were incubated with miR-302a-3pmimic or inhibitor in the presence or absence of erastin or RSL3. Cell viability, colony numbers, lactate dehydrogenase (LDH) releases, lipid peroxidation and intracellular iron level were measured. Besides, the synergistic effects of cisplatin and paclitaxel with miR-302a-3p were determined. miR-302a-3p level was reduced in human NSCLCs cells and tissues. ThemiR-302a-3p mimic induced lipid peroxidation, iron overload and ferroptosis, thereby inhibiting cell growth and colony formation of NSCLCs cells. Conversely, the miR-302a-3p inhibitor block ederastin- or RSL3-related ferroptosis and tumor suppression. Additionally, we found that miR-302a-3p directly bound to the 3'-untranslational region of ferroportin to decrease its protein expression, and that ferroportin overexpression significantly prevented miR-302a-3p mimic-induced ferroptosis and tumor inhibition. Moreover, the miR-302a-3p mimic sensitized NSCLCs cells to cisplatin and paclitaxel chemotherapy. miR-302a-3p functions as a tumor inhibitor, at least partly, via targeting ferroportin to induce ferroptosis of NSCLCs.

Zinc transporter ZIP7 is a novel determinant of ferroptosis.

Ferroptosis is a newly described form of regulated cell death triggered by oxidative stresses and characterized by extensive lipid peroxidation and membrane damages. The name of ferroptosis indicates that the ferroptotic death process depends on iron, but not other metals, as one of its canonical features. Here, we reported that zinc is also essential for ferroptosis in breast and renal cancer cells. Zinc chelator suppressed ferroptosis, and zinc addition promoted ferroptosis, even during iron chelation. By interrogating zinc-related genes in a genome-wide RNAi screen of ferroptosis, we identified SLC39A7, encoding ZIP7 that controls zinc transport from endoplasmic reticulum (ER) to cytosol, as a novel genetic determinant of ferroptosis. Genetic and chemical inhibition of the ZIP7 protected cells against ferroptosis, and the ferroptosis protection upon ZIP7 knockdown can be abolished by zinc supplementation. We found that the genetic and chemical inhibition of ZIP7 triggered ER stresses, including the induction of the expression of HERPUD1 and ATF3. Importantly, the knockdown of HERPUD1 abolished the ferroptosis protection phenotypes of ZIP7 inhibition. Together, we have uncovered an unexpected role of ZIP7 in ferroptosis by maintaining ER homeostasis. These findings may have therapeutic implications for human diseases involving ferroptosis and zinc dysregulations.

Tumor heterogeneity in autophagy-dependent ferroptosis.

Macroautophagy (hereafter referred to as "autophagy") is a lysosome-mediated degradation process that plays a complex role in cellular stress, either promoting survival or triggering death. Early studies suggest that ferroptosis, an iron-dependent form of regulated cell death, is not related to autophagy. Conversely, recent evidence indicates that the molecular machinery of autophagy facilitates ferroptosis through the selective degradation of anti-ferroptosis regulators. However, the mechanism of autophagy-dependent ferroptosis remains incompletely understood. Here, we examine the early dynamic change in protein expression of autophagic (e.g., MAP1LC3B and SQSTM1) or ferroptotic (e.g., SLC7A11 and GPX4) regulators in 60 human cancer cell lines in response to two classical ferroptosis activators (erastin and RSL3) in the absence or presence of the lysosomal inhibitor chloroquine. Compared to erastin, RSL3 exhibits wider and stronger activity in the upregulation of MAP1LC3B-II or downregulation of SQSTM1 in 80% (48/60) or 63% (38/60) of cell lines, respectively. Both RSL3 and erastin failed to affect SLC7A11 expression, but they led to GPX4 downregulation in 12% (7/60) and 3% (2/60) of cell lines, respectively. Additionally, the intracellular iron exporter SLC40A1/ferroportin-1 was identified as a new substrate for autophagic elimination, and its degradation by SQSTM1 promoted ferroptosis in vitro and in xenograft tumor mouse models. Together, these findings show tumor heterogeneity in autophagy-dependent ferroptosis, which might have different biological behaviors with regard to the dynamic characteristics of cell death.Abbreviations: ATG: Autophagy-related; CQ: Chloroquine; GPX4: Glutathione peroxidase 4; MAP1LC3B/LC3: Microtubule-associated protein 1 light chain 3 beta: NCOA4: Nuclear Receptor Coactivator 4; ROS: Reactive Oxygen Species; SLC40A1/ferroportin-1: Solute Carrier family 40 Member 1; SLC7A11: Solute Carrier Family 7 Member 11; SQSTM1/p62: Sequestosome 1.

The Oral Ferroportin Inhibitor VIT-2763 Improves Erythropoiesis without Interfering with Iron Chelation Therapy in a Mouse Model of ß-Thalassemia.

In ß-thalassemia, ineffective erythropoiesis leads to anemia and systemic iron overload. The management of iron overload by chelation therapy is a standard of care. However, iron chelation does not improve the ineffective erythropoiesis. We recently showed that the oral ferroportin inhibitor VIT-2763 ameliorates anemia and erythropoiesis in the Hbbth3/+ mouse model of ß-thalassemia. In this study, we investigated whether concurrent use of the iron chelator deferasirox (DFX) and the ferroportin inhibitor VIT-2763 causes any pharmacodynamic interactions in the Hbbth3/+ mouse model of ß-thalassemia. Mice were treated with VIT-2763 or DFX alone or with the combination of both drugs once daily for three weeks. VIT-2763 alone or in combination with DFX improved anemia and erythropoiesis. VIT-2763 alone decreased serum iron and transferrin saturation (TSAT) but was not able to reduce the liver iron concentration. While DFX alone had no effect on TSAT and erythropoiesis, it significantly reduced the liver iron concentration alone and in the presence of VIT-2763. Our results clearly show that VIT-2763 does not interfere with the iron chelation efficacy of DFX. Furthermore, VIT-2763 retains its beneficial effects on improving ineffective erythropoiesis when combined with DFX in the Hbbth3/+ mouse model. In conclusion, co-administration of the oral ferroportin inhibitor VIT-2763 and the iron chelator DFX is feasible and might offer an opportunity to improve both ineffective erythropoiesis and iron overload in ß-thalassemia.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era.

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

Inhibition of ferroptosis attenuates busulfan-induced oligospermia in mice.

Busulfan is commonly used for cancer chemotherapy, nevertheless it cause male infertility via damaging the germ cells. Therefore, the underlying mechanism should be explored. In the present study, we demonstrated for the first time that ferroptosis was involved in busulfan-induced oligospermia in mice. Mice were given testicular injection of busulfan on both sides at the dose of 4 mg/kg body weight to establish the model of oligospermia. Four weeks later, the results showed that busulfan-treated mice exhibited decreased sperm concentration and motility, along with features of typical ferroptosis in testis, such as increased malondialdehyde (MDA) content and prostaglandin-endoperoxide synthase (PTGS2) mRNA expression, and decreased NADPH content. Inhibition of ferroptosis by ferrostatin-1 (Fer-1) or deferoxamine (DFO) partially alleviated busulfan-induced oligospermia in mice. Additionally, we also revealed that busulfan treatment induced spermatogenic cells ferroptosis by down-regulating nuclear factor-E2-related factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4) expressions, and decreasing iron efflux through reduction of ferroportin 1 (FPN1) expression. Fer-1 or DFO obviously reversed busulfan-induced ferroptosis by increasing Nrf2, GPX4 and FPN1 expressions. Furthermore, after activation of Nrf2 by sulforaphane, sperm concentration and motility in busulfan-treated mice increased, accompanied by enhanced expressions of GPX4 and FPN1. These findings imply that busulfan-induced ferroptosis might be mediated via inhibition of Nrf2-GPX4 (FPN1) signaling pathway, and highlight that targeting ferroptosis serves as a potential strategy for prevention of busulfan-induced damage and male infertility.

Ferroportin inhibition attenuates plasma iron, oxidant stress, and renal injury following red blood cell transfusion in guinea pigs.

BACKGROUND: Red blood cell (RBC) transfusions result in the sequestration and metabolism of storage-damaged RBCs within the spleen and liver. These events are followed by increased plasma iron concentrations that can contribute to oxidant stress and cellular injury. We hypothesized that administration of a ferroportin inhibitor (FPN-INH) immediately after acute RBC exchange transfusion could attenuate posttransfusion circulatory compartment iron exposure, by retaining iron in spleen and hepatic macrophages. STUDY DESIGN AND METHODS: Donor guinea pig blood was leukoreduced, and RBCs were preserved at 4°C. Recipient guinea pigs (n = 5/group) were exchange transfused with donor RBCs after refrigerator preservation and dosed intravenously with a small-molecule FPN-INH. Groups included transfusion with vehicle (saline), 5 mg/kg or 25 mg/kg FPN-INH. A time course of RBC morphology, plasma non-transferrin-bound iron (NTBI) and plasma hemoglobin (Hb) were evaluated. End-study spleen, liver, and kidney organ iron levels, as well as renal tissue oxidation and injury, were measured acutely (24-hr after transfusion). RESULTS: RBC transfusion increased plasma NTBI, with maximal concentrations occurring 8 hours after transfusion. Posttransfusion iron accumulation resulted in tubule oxidation and acute kidney injury. FPN inhibition increased spleen and liver parenchymal/macrophage iron accumulation, but attenuated plasma NTBI, and subsequent renal tissue oxidation/injury. CONCLUSION: In situations of acute RBC transfusion, minimizing circulatory NTBI exposure by FPN inhibition may attenuate organ-specific adverse consequences of iron exposure.

High RhCG expression predicts poor survival and promotes migration and proliferation of gastric cancer via keeping intracellular alkaline.

Advanced gastric cancer (GC) is aggressive with a high mortality rate. Rhesus family, C glycoprotein (RhCG) participates in tumor progression in many cancers, however its function in GC is still unknown. Here, we showed that RhCG was overexpressed in GC tissues at mRNA (P = 0.036) and protein levels (P < 0.05) compared with normal tissues. High RhCG level was correlated with poor differentiation (P = 0.037), TNM stage (P < 0.001), high HER-2 level (P = 0.018) and worse prognosis (P < 0.001). Cox proportional hazard model indicated that RhCG level was an independent prognostic biomarker. RhCG knockdown significantly decreased pHi and impeded tumor cellular proliferation, migration and invasion and repressed ß-catenin and c-myc expression in GC cells. Moreover, GC cells with high RhCG level had reduced oxaliplatin efficacy suggesting a role for RhCG as a therapeutic target for GC. Our findings revealed a function of RhCG in cancer pathogenesis, invasion and metastasis in human GC. We suggest that RhCG act may as a novel prognostic indicator and a therapeutic target for gastric adenocarcinoma.

Salmonella effector SpvB interferes with intracellular iron homeostasis via regulation of transcription factor NRF2.

Iron is a necessary nutrient for humans and nearly all bacterial species. During Salmonella infection, macrophages limit the availability of iron to intracellular pathogens in one of the central components of nutritional immunity. However, Salmonella also have mechanisms to interfere with the antimicrobial effect of host iron withdrawal and meet their own nutrient requirements by scavenging iron from the host. Here, we provide what is, to our knowledge, the first report that SpvB, a pSLT-encoded cytotoxic protein whose function is associated with the intracellular stage of salmonellosis, perturbs macrophage iron metabolism, thereby facilitating Salmonella survival and intracellular replication. In investigating the underlying mechanism, we observed that the Salmonella effector SpvB down-regulated nuclear factor erythroid-derived 2-related factor 2 (NRF2), and its C-terminal domain was necessary and sufficient for NRF2 degradation via the proteasome pathway. Decreased NRF2 expression in the nucleus resulted in a decrease in its transcriptional target ferroportin, encoding the sole macrophage iron exporter, thus ultimately decreasing iron efflux and increasing the intracellular iron content. Additionally, SpvB contributes to the pathogenesis of Salmonella including severe serum hypoferremia, increased splenic and hepatic bacterial burden, and inflammatory injury in vivo. Together, our observations uncovered a novel contribution of SpvB to Salmonella pathology via interference with host intracellular iron metabolism.-Yang, S., Deng, Q., Sun, L., Dong, K., Li, Y., Wu, S., Huang, R. Salmonella effector SpvB interferes with intracellular iron homeostasis via regulation of transcription factor NRF2.

Inhibition of ZIP4 reverses epithelial-to-mesenchymal transition and enhances the radiosensitivity in human nasopharyngeal carcinoma cells.

ZIP4 is a zinc transporter involved in epithelial cell morphology and migration in various cancers. In the epithelial-to-mesenchymal transition (EMT), epithelial cells transition into mesenchymal cells. The EMT plays a crucial role in invasiveness and metastasis during tumorigenesis. The aim of this study was to investigate the role of ZIP4 in the invasiveness and radiosensitivity of human nasopharyngeal carcinoma (NPC). In this study, results from 99 human patients with NPC showed that ZIP4 expression levels significantly correlated with a higher TN (tumor, lymph node) classification, as well as shorter overall survival (OS), recurrence-free survival (RFS), and distant metastasis-free survival (DMFS). Forced overexpression of ZIP4 promoted the migration and invasion of C666-1 cells through regulation of the EMT process. In contrast, ZIP4 silencing by lentivirus-mediated shRNA inhibited the EMT and metastasis of C666-1 cells in vitro and in vivo. Importantly, protein microarray analyses showed that downregulation of ZIP4 in C666-1 cells resulted in the decreased abundance of phosphoinositide 3-kinase (PI3K) p85 (Tyr607), phosphorylated (p)-Akt (Ser473), phosphorylated (p)-Akt (Thr308), and phosphorylated glycogen synthase kinase 3ß (pGSK3ß; Ser9). These data suggest that ZIP4 induces the EMT and promotes migration and invasion via the PI3K/Akt signaling pathway in NPC. Moreover, ZIP4 silencing significantly enhanced radiation-induced apoptosis and growth inhibition of human C666-1 cells in vitro and enhanced the antitumor activity of ionizing radiation (IR), leading to tumor growth inhibition in vivo. These results demonstrate that ZIP4 is a novel prognostic factor for malignant NPC progression. More importantly, targeting ZIP4, along with radiotherapy, may be an effective new treatment for NPC.

microRNA-199a-5p suppresses glioma progression by inhibiting MAGT1.

microRNAs (miRNAs) can function as a tumor suppressor or oncogenic genes in human cancers. Alternation expression of miR-199a-5p has been revealed in several human cancers. However, its expression pattern and biological roles in glioma remain unclear. Expression levels of miR-199a-5p in glioma were evaluated at first. The effects of miR-199a-5p expression on cell proliferation, migration, and invasion were investigated using the MTT assay, wound-healing assay, and transwell invasion assay. The expression of miR-199a-5p was found to be reduced in glioma cell lines. Overexpression of miR-199a-5p inhibits glioma cell proliferation, migration, and invasion in vitro. Furthermore, the target of miR-199a-5p was predicted by TargetScan and validated by luciferase activity reporter assay. We found magnesium transporter 1 (MAGT1) was a direct target of miR-199a-5p. Overexpression of MAGT1 reversed the effects of miR-199a-5p on glioma cell behaviors. Taken together, our study revealed that miR-199a-5p and MAGT1 have the potential to be used as a biomarker for glioma.

Activity of a Synthetic Peptide Targeting MgtC on Pseudomonas aeruginosa Intramacrophage Survival and Biofilm Formation.

Antivirulence strategies aim to target pathogenicity factors while bypassing the pressure on the bacterium to develop resistance. The MgtC membrane protein has been proposed as an attractive target that is involved in the ability of several major bacterial pathogens, including Pseudomonas aeruginosa, to survive inside macrophages. In liquid culture, P. aeruginosa MgtC acts negatively on biofilm formation. However, a putative link between these two functions of MgtC in P. aeruginosa has not been experimentally addressed. In the present study, we first investigated the contribution of exopolysaccharides (EPS) in the intramacrophage survival defect and biofilm increase of mgtC mutant. Within infected macrophages, expression of EPS genes psl and alg was increased in a P. aeruginosa mgtC mutant strain comparatively to wild-type strain. However, the intramacrophage survival defect of mgtC mutant was not rescued upon introduction of psl or alg mutation, suggesting that MgtC intramacrophage role is unrelated to EPS production, whereas the increased biofilm formation of mgtC mutant was partially suppressed by introduction of psl mutation. We aimed to develop an antivirulence strategy targeting MgtC, by taking advantage of a natural antagonistic peptide, MgtR. Heterologous expression of mgtR in P. aeruginosa PAO1 was shown to reduce its ability to survive within macrophages. We investigated for the first time the biological effect of a synthetic MgtR peptide on P. aeruginosa. Exogenously added synthetic MgtR peptide lowered the intramacrophage survival of wild-type P. aeruginosa PAO1, thus mimicking the phenotype of an mgtC mutant as well as the effect of endogenously produced MgtR peptide. In correlation with this finding, addition of MgtR peptide to bacterial culture strongly reduced MgtC protein level, without reducing bacterial growth or viability, thus differing from classical antimicrobial peptides. On the other hand, the addition of exogenous MgtR peptide did not affect significantly biofilm formation, indicating an action toward EPS-independent phenotype rather than EPS-related phenotype. Cumulatively, our results show an antivirulence action of synthetic MgtR peptide, which may be more potent against acute infection, and provide a proof of concept for further exploitation of anti-Pseudomonas strategies.

Blockage of SLC31A1-dependent copper absorption increases pancreatic cancer cell autophagy to resist cell death.

OBJECTIVES: Clinical observations have demonstrated that copper levels elevate in several cancer types, and copper deprivation is shown to inhibit tumour angiogenesis and growth in both animal models and preclinical trials. However, the content of copper in pancreatic duct adenocarcinoma (PDAC) and whether it is a potential therapy target is still unknown. MATERIALS AND METHODS: The levels of copper in PDAC specimens were detected by ICP-MS assays. Copper depletion in Panc-1 or MiaPaCa-2 cells was conducted via copper transporter 1 (SLC31A1) interference and copper chelator tetrathiomolybdate (TM) treatment. The effects of copper deprivation on cancer cells were evaluated by cell proliferation, migration, invasion, colony formation and cell apoptosis. The mechanism of copper deprivation-caused cancer cell quiescence was resolved through mitochondrial dysfunction tests and autophagy studies. The tumour-suppression experiments under the condition of copper block and/or autophagy inhibition were performed both in vitro and in xenografted mice. RESULTS: SLC31A1-dependent copper levels are correlated with the malignant degree of pancreatic cancer. Blocking copper absorption could inhibit pancreatic cancer progression but did not increase cell death. We found that copper deprivation increased mitochondrial ROS level and decreased ATP level, which rendered cancer cells in a dormant state. Strikingly, copper deprivation caused an increase in autophagy to resist death of pancreatic cancer cells. Simultaneous treatment with TM and autophagy inhibitor CQ increased cell death of cancer cells in vitro and retarded cancer growth in vivo. CONCLUSIONS: These findings reveal that copper deprivation-caused cell dormancy and the increase in autophagy is a reason for the poor clinical outcome obtained from copper depletion therapies for cancers. Therefore, the combination of autophagy inhibition and copper depletion is potentially a novel strategy for the treatment of pancreatic cancer and other copper-dependent malignant tumours.

Molecular signatures and functional analysis of beige adipocytes induced from in vivo intra-abdominal adipocytes.

Beige adipocytes can be induced from white adipocytes and precursors upon stimulation by cold temperatures and act like brown adipocytes to increase energy expenditure. Most in vivo studies examining the mechanisms for the induction of beige adipocytes have focused on subcutaneous white adipose tissue (sWAT; benign fat) in the mouse. How intra-abdominal WAT (aWAT; malignant fat) develops into beige adipocytes remains obscure, largely because there is a lack of a good animal model for the induction of beige adipocytes from aWAT. To better understand the development of beige adipocytes from mammalian WATs, especially aWAT, we induced beige adipocytes from bat aWAT and mouse sWAT by exposure to cold temperatures and analyzed their molecular signatures. RNA sequencing followed by whole genome-wide expression analysis shows that beige adipocytes induced from bat aWAT, rather than sWAT, have molecular signatures resembling those of mouse sWAT-induced beige adipocytes and exhibit dynamic profiles similar to those of classical brown adipocytes. In addition, we identified molecular markers that were highly enriched in beige adipocytes and conserved between bat aWAT and mouse sWAT, a set that included the genes Uqcrc1 and Letm1. Furthermore, knockdown of Uqcrc1 and Letm1 expression shows that they are required not only for beige adipocyte differentiation but also for preadipocyte maturation. This study presents a new model for research into the induction of beige adipocytes from aWAT in vivo, which, when combined with models where beige adipocytes are induced from sWAT, provides insight into therapeutic approaches for combating obesity-related diseases in humans.

Biochemical characterization and chemical inhibition of PfATP4-associated Na+-ATPase activity in Plasmodium falciparum membranes.

The antimalarial activity of chemically diverse compounds, including the clinical candidate cipargamin, has been linked to the ATPase PfATP4 in the malaria-causing parasite Plasmodium falciparum The characterization of PfATP4 has been hampered by the inability thus far to achieve its functional expression in a heterologous system. Here, we optimized a membrane ATPase assay to probe the function of PfATP4 and its chemical sensitivity. We found that cipargamin inhibited the Na+-dependent ATPase activity present in P. falciparum membranes from WT parasites and that its potency was reduced in cipargamin-resistant PfATP4-mutant parasites. The cipargamin-sensitive fraction of membrane ATPase activity was inhibited by all 28 of the compounds in the "Malaria Box" shown previously to disrupt ion regulation in P. falciparum in a cipargamin-like manner. This is consistent with PfATP4 being the direct target of these compounds. Characterization of the cipargamin-sensitive ATPase activity yielded data consistent with PfATP4 being a Na+ transporter that is sensitive to physiologically relevant perturbations of pH, but not of [K+] or [Ca2+]. With an apparent Km for ATP of 0.2 mm and an apparent Km for Na+ of 16-17 mm, the protein is predicted to operate at below its half-maximal rate under normal physiological conditions, allowing the rate of Na+ efflux to increase in response to an increase in cytosolic [Na+]. In membranes from a cipargamin-resistant PfATP4-mutant line, the apparent Km for Na+ is slightly elevated. Our study provides new insights into the biochemical properties and chemical sensitivity of an important new antimalarial drug target.

Suppression of ferroportin expression by cadmium stimulates proliferation, EMT, and migration in triple-negative breast cancer cells.

Cadmium (Cd) has been linked to a variety of cancers, including breast cancer; however, the molecular mechanism of its carcinogenic activity is not fully understood. To this end, the present study investigated the roles of ferroportin (FPN), a prognostic marker of breast cancer, in Cd-induced stimulation of cell proliferation and cell migration. Triple-negative MDA-MB-231 cells were treated with 1-3 µM Cd. The cells exhibited significant reduction in FPN expression and concomitant increase in iron concentration. Cells treated with Cd for 8 weeks displayed elevated proliferative and migratory activities which were inversely related with FPN expression. Reduced FPN expression also resulted in EMT as indicated by an increase in the expression of E-cadherin, and a decrease in the expression of N-cadherin, Twist and Slug. Further investigation revealed that Cd suppressed FPN expression at least partially by activating TGF-ß, a known regulator of FPN expression. Taken together, these results indicate that Cd-induced stimulation of MDA-MB-231 cell proliferation, EMT, and migration is brought about by suppression of FPN expression and associated disruption of iron homeostasis.

Knockdown of ferroportin accelerates erastin-induced ferroptosis in neuroblastoma cells.

OBJECTIVE: Ferroptosis is a new-found iron-dependent form of non-apoptotic regulated cell death (RCD), which is activated on therapy with several antitumor agents, but the potential mechanism remains unclear. Erastin, exhibiting selectivity for RAS-mutated cancer cells, induces ferroptosis by increasing iron and lipid reactive oxygen species (ROS) levels in cell. Ferroportin (Fpn), the sole iron export protein, participates in the regulation of intracellular iron concentration. In this study, we investigated the role of Fpn on ferroptosis induced by erastin in SH-SY5Y cells. MATERIALS AND METHODS: The cell viability was determined by CellTiter 96® AQueous Non-Radioactive Cell Proliferation Assay kit. The activity of caspase-3 was measured by ELISA kit. qRT-PCR was performed to examine the mRNA expression of Fpn. Western blot assay was conducted to examine the expression level of marker proteins. Specific commercial kits were used to examine the levels of MDA, ROS and iron in cells, respectively. RESULTS: Ferroptosis was evaluated by intracellular lipid ROS level and iron concentration. Hepcidin could prevent erastin-induced ferroptosis by degrading Fpn. Erastin (5 µg/mL) was observed to induce ferroptosis in neuroblastoma cells at 6 hours, which was promoted by knockdown of Fpn. The expression of Fpn gene and protein was decreased in SH-SY5Y cells treated with erastin. After treatment with erastin, Fpn siRNA transfection in SH-SY5Y cells was able to accelerate ferroptosis-associated phenotypic changes. Fpn acted as a negative regulator of ferroptosis by reducing intracellular iron concentration. Knockdown of Fpn enhanced anticancer activity of erastin. CONCLUSIONS: These results suggested that knockdown of Fpn accelerated erastin-induced ferroptosis by increasing iron-dependent lipid ROS accumulation, highlighting Fpn as a potential therapeutic target site for neuroblastoma. Thus, Fpn inhibitors may provide new access for chemosensitization of neuroblastoma.