| 1. |
- Blockhuys, Stephanie, 1983, et al.
(författare)
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Single-cell tracking demonstrates copper chaperone Atox1 to be required for breast cancer cell migration
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:4, s. 2014-2019
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Tidskriftsartikel (refereegranskat)abstract
- Copper ions are needed for several hallmarks of cancer. However, the involved pathways, mechanisms, and copper-binding proteins are mostly unknown. We recently found that cytoplasmic Antioxidant 1 copper chaperone (Atox1), which is up-regulated in breast cancer, is localized at the lamellipodia edges of aggressive breast cancer cells. To reveal molecular insights into a putative role in cell migration, we here investigated breast cancer cell (MDA-MB-231) migration by video microscopy as a function of Atox1. Tracking of hundreds of individual cells (per condition) over a 9-h time series revealed that cell migration velocity and directionality are significantly reduced upon Atox1 silencing in the cells. Because silencing of the copper transporter ATP7A also reduced cell migration, these proteins appear to be on the same pathway, suggesting that their well-known copper transport activity is involved. In-cell proximity ligation assays demonstrated that Atox1, ATP7A, and the proenzyme of lysyl oxidase (LOX; copper-loaded via ATP7A) are all in close proximity and that LOX activity is reduced upon Atox1 silencing in the cells. Since LOX is an established player in cancer cell migration, our results imply that Atox1 mediates breast cancer cell migration via coordinated copper transport in the ATP7A-LOX axis. Because individual cell migration is an early step in breast cancer metastasis, Atox1 levels in tumor cells may be a predictive measure of metastasis potential and serve as a biomarker for copper depletion therapy.
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| 2. |
- Zhang, Xiaolu, 1983, et al.
(författare)
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Memo1 binds reduced copper ions, interacts with copper chaperone Atox1, and protects against copper-mediated redox activity invitro
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 119:37
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Tidskriftsartikel (refereegranskat)abstract
- The protein mediator of ERBB2-driven cell motility 1 (Memo1) is connected to many signaling pathways that play key roles in cancer. Memo1 was recently postulated to bind copper (Cu) ions and thereby promote the generation of reactive oxygen species (ROS) in cancer cells. Since the concentration of Cu as well as ROS are increased in cancer cells, both can be toxic if not well regulated. Here, we investigated the Cu-binding capacity of Memo1 using an array of biophysical methods at reducing as well as oxidizing conditions invitro. We find that Memo1 coordinates two reduced Cu (Cu(I)) ions per protein, and, by doing so, the metal ions are shielded from ROS generation. In support of biological relevance, we show that the cytoplasmic Cu chaperone Atox1, which delivers Cu(I) in the secretory pathway, can interact with and exchange Cu(I) with Memo1 invitro and that the two proteins exhibit spatial proximity in breast cancer cells. Thus, Memo1 appears to act as a Cu(I) chelator (perhaps shuttling the metal ion to Atox1 and the secretory path) that protects cells from Cu-mediated toxicity, such as uncontrolled formation of ROS. This Memo1 functionality may be a safety mechanism to cope with the increased demand of Cu ions in cancer cells.
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| 3. |
- Zhang, Xiaolu, 1983, et al.
(författare)
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The Caenorhabditis elegans homolog of human copper chaperone Atox1, CUC-1, aids in distal tip cell migration
- 2020
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Ingår i: Biometals. - : Springer Science and Business Media LLC. - 0966-0844 .- 1572-8773. ; :33, s. 147-157
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Tidskriftsartikel (refereegranskat)abstract
- Cell migration is a fundamental biological process involved in for example embryonic development, immune system and wound healing. Cell migration is also a key step in cancer metastasis and the human copper chaperone Atox1 was recently found to facilitate this process in breast cancer cells. To explore the role of the copper chaperone in other cell migration processes, we here investigated the putative involvement of an Atox1 homolog in Caenorhabditis elegans, CUC-1, in distal tip cell migration, which is a key process during the development of the C. elegans gonad. Using knock-out worms, in which the cuc-1 gene was removed by CRISPR-Cas9 technology, we probed life span, brood size, as well as distal tip cell migration in the absence or presence of supplemented copper. Upon scoring of gonads, we found that cuc-1 knock-out, but not wild-type, worms exhibited distal tip cell migration defects in approximately 10-15% of animals and, had a significantly reduced brood size. Importantly, the distal tip cell migration defect was rescued by a wild-type cuc-1 transgene provided to cuc-1 knock-out worms. The results obtained here for C. elegans CUC-1 imply that Atox1 homologs, in addition to their well-known cytoplasmic copper transport, may contribute to developmental cell migration processes.
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| 4. |
- Zhang, Xiaolu, 1983
(författare)
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COPPER BINDING PROTEINS IN BREAST CANCER : CELLULAR AND MOLECULAR MECHANISMS
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cancer is one of the leading causes of human death. However, the mechanisms governing cancer are still not fully understood. Elevated levels of copper (Cu) have been observed in both cancerous tissues and the serum of cancer patients. Cu ions play a crucial role in supporting cancer by activating Cu-dependent enzymes, which promote cancer cell proliferation, angiogenesis, and metastasis. Cu ions can undergo redox reactions, switching between the +1 and +2 oxidation states. Free Cu ions can therefore catalyze the production of reactive oxygen species (ROS), which may damage biomolecules. To avoid such reactions, Cu ions are controlled and transported by dedicated Cu transport proteins in cells. This thesis focuses on two Cu-binding proteins, antioxidant 1 Cu chaperone (Atox1) and mediator of cell motility 1 (Memo1). Previous studies have shown that Atox1 is upregulated in breast cancer cells and patients. The results of Paper I indicate that Atox1 knockdown significantly reduces the velocity and directionality of breast cancer cell migration. Data in Paper I also show close proximity between Atox1 and the Cu-dependent enzyme lysyl oxidase (LOX) in cells. These results imply that Cu transport in the Atox1-ATP7A-LOX axis is crucial for cancer cell migration. I also investigated the role of an Atox1 homolog, CUC-1, in Caenorhabditis elegans (C. elegans) cell migration during development (Paper II). CUC-1 knock-out worms have more developmental defects, implying that Atox1-like proteins contribute to cell migration during development. Memo1, connected to many oncogenic signaling pathways, was recently suggested to bind oxidized Cu ions and promote ROS generation. In contrast, my work shows that Memo1 binds the reduced form of Cu and protects against Cu-induced ROS generation in vitro and in breast cancer cells (Paper III and IV). Memo1 knockdown and external Cu addition significantly decrease cell viability and increase ROS levels in breast cancer cells. This Memo1 functionality may serve as a protective mechanism, allowing cancer cells to handle the increased demand of Cu ions in cancer-related processes. In conclusion, my research provides important new discoveries for the Cu-binding proteins Atox1 and Memo1 that may be relevant for future cancer treatments.
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| 5. |
- Zhang, Xiaolu, 1983, et al.
(författare)
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Correlation between Cellular Uptake and Cytotoxicity of Fragmented α-Synuclein Amyloid Fibrils Suggests Intracellular Basis for Toxicity
- 2020
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Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 11:3, s. 233-241
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation and intracellular deposition of the protein α-synuclein is an underlying characteristic of Parkinson's disease. α-Synuclein assemblies also undergo cell-cell spreading, facilitating propagation of their cellular pathology. Understanding how cellular interactions and uptake of extracellular α-synuclein assemblies depend on their physical attributes is therefore important. We prepared fragmented fluorescently labeled α-synuclein amyloid fibrils of different average lengths (∼80 nm to >1 μm) and compared their interactions with SH-SY5Y cells. We report that fibrils of all lengths, but not monomers, bind avidly to the cell surface. Their uptake is inversely dependent on their average size, occurs via a heparan sulfate dependent endocytic route, and appears to have a size cutoff of ∼400 nm. The uptake of α-synuclein fibrils, but not monomers, correlates with their cytotoxicity as measured by reduction in metabolic activity, strongly suggesting an intracellular basis for α-synuclein fibril toxicity, likely involving endolysosomes.
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| 6. |
- Zhang, Xiaolu, 1983, et al.
(författare)
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Memo1 reduces copper-mediated reactive oxygen species in breast cancer cells
- 2023
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Ingår i: Journal of Inorganic Biochemistry. - 1873-3344 .- 0162-0134. ; 247
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Tidskriftsartikel (refereegranskat)abstract
- The mediator of ERBB2-driven cell motility protein 1, Memo1, plays important roles in cancer signaling pathways. We recently reported Memo1 to coordinate reduced copper ions and protect them from reactive oxygen species (ROS) generation in vitro. We here assess if this Memo1 activity is at play in breast cancer cells. Copper additions to MDA-MB-231 cells promoted cell death, and this toxicity was exaggerated when Memo1 expression was reduced by silencing RNA. Using three different commercial ROS probes, we revealed that copper additions increased intracellular ROS levels, and these were further elevated when Memo1 expression was silenced. We propose that, in addition to other functions, Memo1 protects cancer cells from unwanted copper-mediated redox reactions. This may be a required safety mechanism in cancer cells as they have a high demand for copper.
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