Search results for: CHO K1 OX1 Stable Cell Line
#35612280 
2022/05/25
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Critical roles for EGFR and EGFR-HER2 clusters in EGF binding of SW620 human carcinoma cells.
Epidermal growth factor (EGF) signalling regulates normal epithelial and other cell growth, with EGF receptor (EGFR) overexpression reported in many cancers. However, the role of EGFR clusters in cancer and their dependence on EGF binding is unclear. We present novel single-molecule total internal reflection fluorescence microscopy of (i) EGF and EGFR in living cancer cells, (ii) the action of anti-cancer drugs that separately target EGFR and human EGFR2 (HER2) on these cells and (iii) EGFR-HER2 interactions. We selected human epithelial SW620 carcinoma cells for their low level of native EGFR expression, for stable transfection with fluorescent protein labelled EGFR, and imaged these using single-molecule localization microscopy to quantify receptor architectures and dynamics upon EGF binding. Prior to EGF binding, we observe pre-formed EGFR clusters. Unexpectedly, clusters likely contain both EGFR and HER2, consistent with co-diffusion of EGFR and HER2 observed in a different model CHO-K1 cell line, whose stoichiometry increases following EGF binding. We observe a mean EGFR : EGF stoichiometry of approximately 4 : 1 for plasma membrane-colocalized EGFR-EGF that we can explain using novel time-dependent kinetics modelling, indicating preferential ligand binding to monomers. Our results may inform future cancer drug developments.Adam J M Wollman, Charlotte Fournier, Isabel Llorente-Garcia, Oliver Harriman, Alex L Payne-Dwyer, Sviatlana Shashkova, Peng Zhou, Ta-Chun Liu, Djamila Ouaret, Jenny Wilding, Akihiro Kusumi, Walter Bodmer, Mark C Leake
2102 related Products with: Critical roles for EGFR and EGFR-HER2 clusters in EGF binding of SW620 human carcinoma cells.
10mg2 Sample KitOne 96-Well Strip Micropl1 SetTwo 96-Well Microplate KiOne 96-Well Strip Micropl0.5 mg1001 Set100 ulOne 96-Well Strip Micropl1 Set
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#21362456 2011/03/06
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Agonist ligand discrimination by the two orexin receptors depends on the expression system.
Despite the recent successes in producing orexin receptor subtype-selective antagonists, these are not commonly available, and therefore, agonist ligands are regularly used to ascribe cell and tissue responses to OX(1) or OX(2) receptors. In the current study, we have compared the native "subtype-selective" agonist, orexin-B, and its reputedly enhanced synthetic variant, Ala(11), d-Leu(15)-orexin-B, in two different recombinant cell lines. Ca2+ elevation was used as readout, and the two "selective" ligands were compared to the subtype-non-selective orexin-A, as is customary with these ligands. In transiently transfected HEK-293 cells, orexin-B showed 9-fold selectivity for the OX(2) receptor and Ala(11), d-Leu(15)-orexin-B 23-fold selectivity, when the potency ratios of ligands were compared between OX(1) and OX(2). In stable CHO-K1 cells, the corresponding values were only 2.6- and 14-fold, respectively. In addition to being low, the selectivity of the ligands was also variable, as indicated by the comparison of the two cell lines. For instance, the relative potency of Ala(11), d-Leu(15)-orexin-B at OX(2) in CHO cells was only 2.3-fold higher than its relative potency at OX(1) in HEK-293 cells; this indicates that Ala(11), d-Leu(15)-orexin-B does not show high enough selectivity for OX(2) to be useful for determination of receptor subtype expression. Comparison of the potencies of orexin-A and -B with respect to a number of published responses in OX(1)-expressing CHO cells, demonstrates that these show great variation: i.e., orexin-A is 1.6-18-fold more potent than orexin-B, depending on the response assessed. These data together suggest that orexin receptor ligands show signal trafficking, which makes agonist-based pharmacology unreliable.Jaana Putula, Pauli M Turunen, Maria H Jäntti, Marie E Ekholm, Jyrki P Kukkonen