The Reagent Roundup is made of brief summaries of publications in which researchers used Azure Biosystems reagents for Western blotting and Western blot quantitation in their studies. It is published every quarter. This quarter’s Reagent Roundup features publications from Duke University School of Medicine, University of Minho School of Medicine, the National Institutes of Health, and Boys Town National Research Hospital.
The role of the epithelial to mesenchymal transition in cancer drug resistance and recurrence
In recent work, Ingruber et al1 hypothesized that head and neck squamous cell carcinoma (HNSCC) cells are in a partial EMT state, able to switch towards epithelial or mesenchymal phenotypes depending on environmental stimuli, and that this switch contributes to their proliferation and resistance to Cisplatin therapy.
As part of this work, the authors carried out chemiluminescent and near-infrared (NIR) fluorescent Western blots to assess levels of EMT protein markers. The authors used Radiance Plus substrate for chemiluminescent Western blots, and fluorescent secondary antibodies for the near-infrared blots. Western blots were then imaged using an Azure c500 imager. The work found that a partial EMT-like pathway appears to contribute to Cisplatin resistance in the cell line used, and that overexpression of an epithelial marker sensitized cells to Cisplatin while reducing a pro-EMT transcription factor. The results suggest future avenues to research and treat drug-resistant cancers.
The epithelial to mesenchymal transition (EMT) is a reversible process in which epithelial cells undergo biochemical changes to adopt a mesenchymal cell phenotype with increased ability to migrate and increased resistance to apoptosis. The EMT can play a role in normal processes such as embryogenesis and wound healing, but also contributes to cancer metastasis and tumor cell migration.
Lipid peroxidation in sporadic Alzheimer's disease
In a recent publication, Ramsden et al2 propose a new hypothesis for the mechanism behind sporadic Alzheimer’s disease (AD) in which the initiating factor of AD is lipid peroxidation of the apolipoprotein E protein (ApoE) and of the ApoE receptor. AzureRed total protein stain was used to detect total protein before immunoblotting. The blots were blocked with Fluorescent Blot Blocking Buffer and imaged with the Azure Sapphire Biomolecular Imager (Figure 3C and Figure 3D).
The peroxidation is hypothesized to disrupt important processes required for memory formation and maintenance of structural integrity, initiating a cascade that leads to AD. The proposed mechanism differs from the amyloid cascade hypothesis and would have important implications for AD prevention and therapeutics if confirmed. Lipid peroxidation is proposed to occur at the ligand-receptor interface of ApoE and the ApoE receptor where there are amino acid residues predicted to be susceptible to peroxidation.
Because polyunsaturated lipids are transported by ApoE, the ApoE-ApoE receptor interface may create a microenvironment favorable to lipid peroxidation. The hypothesis accounts for several observations about AD including the anatomic areas of the brain known to be affected, the fact that ApoE variants are associated with sporadic AD, that ApoE is enriched in neurite plaque cores, the significance of amyloid plaques and neurofibrillary tangles, and evidence that lipid peroxidation occurs very early in sporadic AD. To test their hypothesis, the authors conducted fluorescence immunoblotting to detect lipid aldehyde-induced crosslinking of ApoE and the ApoE receptor ApoER2.
Based on these in vitro experiments and additional experiments including immunohistochemistry of human brain samples, the authors conclude that their hypothesis is consistent with experimental observations and deserves additional study.
DISCOVER: Azure Sapphire Biomolecular Imager
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A study of the anti-inflammatory effects of LRP1 ligands
Mantuano et al4 used 3 ECL substrates (Radiance, Radiance Q, and Radiance Plus) from Azure Biosystems in their investigation of the anti-inflammatory action of three ligands of LDL receptor protein-1 (LRP1). Chemiluminescent Western blots imaged on the Azure c300 or on film were key to the study as the authors assessed the components required for enzymatically-inactive tissue-type plasminogen activator (El-tPA), activated α2-macroglobulin (a2M), and a soluble derivative of nonpathogenic cellular prion protein (S-PrP) to activate signal transduction in macrophages.
The results found indicate that lipid rafts and the N-methyl-D-aspartic acid (NMDA) receptor are required by all three ligands studied, while LRP1 was not required by two of the ligands when the ligands were present at high concentrations. In addition to the effects on cell signaling, the ligands studied were also shown to prevent lipopolysaccharide (LPS)-induced shedding of LRP1. Since the soluble LRP1 product is pro-inflammatory, blocking this process is another way LRP1 ligands could convey an anti-inflammatory effect. The differences uncovered between the three ligands’ requirements for signal transduction activation might help clarify their effects on macrophages in various states of differentiation.
DISCOVER: Azure 300 Imager
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- Ingruber J, et al. Interplay between partial EMT and Cisplatin resistance as the drivers for recurrence in HNSCC. Biomedicines. 2022;10(10):2482.
- Ramsden CE, et al. Lipid peroxidation induced ApoE receptor-ligand disruption as a unifying hypothesis underlying sporadic Alzheimer’s disease in humans. J Alzheimers Dis. 2022;87(3):1251-1290.
- Mantuano E et al. The LRP1/CD91 ligands, tissue-type plasminogen activator, a2-macroglobulin, and soluble cellular prion protein have distinct co-receptor requirements for activation of cell-signaling. Sci Rep. 2022;12(1):17594.
- Jäntti MA, et al. Palmitate and thapsigargin have contrasting effects on ER membrane lipid composition and ER proteostasis in neuronal cells. Biochim Biophys Acta Mol Cell Biol Lipids. 2022;1867(11):159219.