Home Select a topic from the list below:
A microfluidic culture model of the human reproductive tract and 28-day menstrual cycle
Xiao et al., Nat Commun. 2017 Mar 28;8:14584. doi: 10.1038/ncomms14584
The technological advances have been shockingly rapid and what one would have not even imagined several years ago has become a fascinating reality. Such is the culture model of the human reproductive tract and 28-day menstrual cycle reported by Teresa Woodruff’s team. The female reproductive system comprises of multiple organs, tissues and hormones and is not an easy task to mimic in vitro and nearly incomprehensible to do so in vivo. The team constructed a microfluidic system, Evatar, which supports murine ovarian follicles to produce hormone profile of a human 28-day menstrual cycle. Evatar controls human reproductive tract and peripheral tissue dynamics in a single, dual and multiple unit microfluidic platforms. The system has a cultured tissue from a mouse ovary and human fallopian tubes, uterus, cervix and liver connected by microfluidic channels and pumps. Menstrual cycle was initiated by follicle-stimulating hormone. In response ovary module produced estrogen. On day 14, the authors added luteinizing hormone to trigger ovulation, which in turn stopped production of estrogen and initiated production of progesterone by ovary. The authors received funding to use Evatar to study diseases that affect women of reproductive age such as polycystic ovary syndrome, fibroids and endometriosis. Other tissues that may be affected by estrogen will be also investigated. What is even more fascinating is the result of the collaborative effort of Woodruff’s team with Ramille NB Shah from Northwestern University in making artificial ovaries (Laronda MM, Rutz AL, Xiao S, Whelan KA, Duncan FE, Roth EW, Woodruff TK, Shah RN, Nat Commun 2017, doi:10.1038/ncomms15261). Three-dimensionally printed gelatin scaffold with ovarian follicles, which house immature eggs, were implanted into mice whose ovaries were removed surgically. Mice were able to mate and bear young naturally. While prosthetic ovaries bearing human follicles seem to be more difficult to construct, the present reports rise hopes for future successes in tissue engineering. (Prepared by Ines Batinic-Haberle, Duke University School of Medicine)
Drug-tolerant persister cancer cells are vulnerable to GPX4 inhibition
Hangauer, M. J. et al., Nature 2017, 551: 247–250
Dependency of a therapy-resistant state of cancer cells on a lipid peroxidase pathway
Viswanathan, V. S. et al., Nature 2017, 547: 453–457
Non-mutationally drug-tolerant persister cells and therapy-resistant mesenchymal cancer cells have a potential role in acquired drug resistance and relapse. Two recent papers in Nature Letters reveal the vulnerability of these drug tolerant persister cells and therapy-resistant mesenchymal cancer cells to Gpx4 inhibition resulting in the initiation of ferroptosis, a newly described form of non-apoptotic programmed cell death characterized by iron-dependent lipid peroxidation.
Viswanathan et al. hypothesized that distinct cell states present in cultured cells could be targeted to uncover vulnerabilities of therapy-resistant cells. They began by selecting cellular and patient-derived signatures of high-mesenchymal states that had previously been proposed to correlate with therapy resistance. They then mined cancer cell-line sensitivity data for compounds whose activities correlate with bulk cell-line expression of the selected resistance markers. Relatedly, Hangauer et al. performed a small-molecule screen in drug-tolerant persister cells derived by exposing BT474 cells to 9 or more days of treatment with 2 μM lapatinib, and the parental cells to identify small molecules that were differentially toxic toward the two cell types. Interestingly, both groups found that ferroptosis inducers, especially Gpx4 inhibitors, were significantly more toxic to both the cell-lines exhibiting high expression of resistance markers as well as the generated persister cells.
Viswanathan et al. found that high baseline expression of the mesenchymal marker ZEB1 strongly correlated with sensitivity to a GPX4 inhibitor (ML210) across 610 cancer cell lines. Knockout of ZEB1 prevented cell death induced by GPX4 inhibition, providing strong evidence that ZEB1 is required for the dependency of high-mesenchymal state cells on GPX4. ZEB1 plays an essential role in cellular lipid uptake, accumulation, mobilization and metabolism and thus provided a link between mesenchymal gene expression, lipid peroxide vulnerability and dependency on GPX4, a selenocysteine-containing enzyme that detoxifies lipid peroxides and thereby prevents the iron-mediated reactions of peroxides that induce ferroptotic cell death.
Hangauer et al. found that persister cells have a disabled antioxidant program characterized by lower levels of reduced glutathione (GSH) and NADPH levels as well as increased basal DCF oxidation levels compared to parental cells. Similar to findings by Viswanathan et al. in therapy-resistant cell lines, persister cells, but not parental cells, were reliant on GPX4 for survival. Cell death induced by GPX4 inhibition was fully or partially prevented by treatment with lipophilic antioxidants ferrostatin-1 and liproxstatin-1, an iron chelator, lipoxygenase inhibitors, and lipid transporter SCP2 inhibitors, but not caspase inhibition, suggesting that these cells were dying a ferroptotic cell death. In vivo, both mesenchymal state and persistor cells were shown to be dependent on GPX4 as evidenced by the immediate regression of GPX4 KO persister or mesenchymal cells upon withdrawal of the ferroptosis inhibitor ferrostatin-1.
One of the most intriguing findings from both papers was that dependency on GPX4 was observed across diverse therapy-resistant states characterized by high expression of ZEB1, including in epithelial-derived carcinomas that had undergone EMT, TGFβ-mediated therapy resistance in melanoma, treatment-induced neuroendocrine transdifferentiation, sarcomas, and the persister state derived by chronic exposure to lapatinib. This broad applicability provides evidence that targeting of GPX4 may represent a therapeutic strategy to prevent acquired drug resistance. Overall, both studies present the exciting conclusion that GPX4 inhibition results in ferroptotic death in therapy resistant, persister cancer cells, presenting a novel strategy to prevent tumor relapse. (Prepared by Collin Heer, The University of Iowa, Iowa City, USA)
Catalán Ú et al., Journal of Functional Foods, Volume 40, January 2018, Pages 280-291
The Mediterranean diet has been widely studied for its cardio-protective and anti-atherosclerotic effects mostly owing to the incorporation of olive oil. Out of all the olive oil-based compounds, Hydroxytyrosol (HT) and its derivatives known as secoiridoids (SEC) are the most abundant and widely-studied category. Many of the beneficial effects of consuming olive oil have been attributed to the presence of HT. Its alleged anti-inflammatory, antioxidant, anticancer or endothelial and vascular functions have been studied in cells, animals, and humans and the evidence highlighting the beneficial effects of this particular compound continues to amass. In a previous study by Catalán et al, HT metabolites were incubated with human aortic endothelial cells (HAEC), and a dose-dependent inhibition of the endothelial dysfunction biomarkers E-selectin, P-selectin, vascular cell adhesion molecule-1 (VCAM-1) and the intracellular cell adhesion molecule-1 (ICAM-1) protein secretion was observed. In continuation of these effects, Catalán et al conducted a study in an ApoE−/− mouse model which was supplemented with olive phenolic extract rich in SEC at a nutritionally appropriate dose of 10 mg/kg/day, to assess the improvement of the endothelial function in the initial steps of atherosclerosis. In comparison with the study in HAECs, for deeper insights into the molecular mechanisms, the research team evaluated the modulation of the mitogen-activated protein kinase (MAPK) family pathway and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). The authors were able to demonstrate that supplementation with olive oil phenolic compounds at nutritionally relevant doses showed a mild attenuation of the initial steps of atherosclerosis through the reduction of endothelial dysfunction biomarkers, specifically E-selectin, VCAM-1, MCP-1, ICAM-1, and F4/80 in the tunica intima, media, and adventitia of the aorta of ApoE −/− mice fed without a pro-inflammatory diet. This was because feeding the ApoE−/− mice with 10 mg/kg/ day of HT derivatives for 12 weeks had statistically significantly (p < 0.05) reduced E-selectin, VCAM-1, MCP-1, ICAM-1, and F4/80 expression compared with the control group in the isolated aorta. The authors explained that this could be associated with the reduction of lymphocyte adhesion and the modulation of the MAPK pathway by HT-metabolites. (Prepared by Viduranga Waisundara, Department of Food Technology, Faculty of Technology, Rajarata University of Sri Lanka, Mihintale, Sri Lanka)
Boulet et al., J. Biol. Chem. 2018, 293(6):1887-1896; PMID: 29237729
Mitochondria are well known to store a variety of metalloproteins that are required for their normal physiology and functions. Metals (e.g., iron, copper, manganese, zinc) are cofactors of metalloenzymes that are required for their activity. Majority of the mitochondrial metalloproteins are synthesized in the cytoplasm and then transported into mitochondria. The mitochondrial localization signal peptide that resides in the N-terminal of the metalloproteins as well as chaperones transport metalloproteins to mitochondria followed by the addition of metal cofactors. Although the metal-transporters for cellular acquisition of iron, zinc, copper and manganese are known, transport of these metal ions (except iron) to mitochondria are not completely understood. Mitoferrin 1 and mitoferrin 2 are known to transport iron to mitochondria. Cytochrome c oxidase (COX) and superoxide dismutase-1 (SOD1) that reside in the mitochondrial intermembrane space (IMS) are two copper containing mitochondrial metalloenzymes that are transported to the IMS by metallochaperone proteins followed by incorporation of copper that is recruited from the mitochondrial matrix. It is currently unknown how copper from the matrix transit through the inner membrane (IM) to the IMS.
Using biochemical and molecular approaches, Boulet et al. recently identified the mammalian Solute Carrier Family 25 Member 3 (SLC25A3) as the transporter for copper in human and murine cell lines trafficking copper from the mitochondrial matrix to the IMS. In mammals, SLC25A3 has been previously shown to transport phosphate. Patients carrying mutant SLC25A3 exhibit multisystem disorders, e.g. lactic acidosis, muscle hypotonia, and cardiomyopathy. siRNA knockdown of SLC25A3 in both murine and human cell lines negatively affected COX biogenesis, which was rescued by the addition of copper-ionophore (CuATSM), suggesting that SLC25A3 is required for COX assembly. Furthermore, in mouse embryo fibroblasts, deletion of SLC25A3 significantly reduced the levels of SOD1 and its chaperone CCS, which was also associated with more than 60% decrease in SOD1 activity and approximately 65% decrease in the levels of mitochondrial matrix copper. These results suggest that SLC25A3 is required both to assemble COX and SOD1 as well as to maintain the mitochondrial pool of copper. Additional studies are needed to determine how SLC25A3 coordinate transport of mitochondrial pool of phosphate and copper. (Prepared by Prabhat Goswami, The University of Iowa, Iowa City, USA)
8365 Keystone Crossing
Suite 107
Indianapolis, IN 46240
(317) 205-9482 PHONE
(317) 205-9481 FAX
info@sfrbm.org
® Copyright 2024 Society for Redox Biology and Medicine
