Granulin-epithelin precursor interacts with heparan sulfate on liver cancer cells.
Bottom Line: Suppression of the HS polymerase exostosin-1 reduced the rGEP binding and rGEP-mediated signaling transduction.Suppression of a specific HS proteoglycan, glypican-3, also showed a partial reduction of rGEP binding and an inhibition on rGEP-mediated activation of AKT.Furthermore, glypican-3 was shown to correlate with the expressions of GEP in clinical samples (Spearman's ρ = 0.363, P = 0.001).
Affiliation: Department of Surgery, Centre for Cancer Research and.Show MeSH
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Mentions: After demonstrating the exogenous rGEP could trigger intracellular signaling pathways in liver cancer cell lines, we reasoned that rGEP might interact with specific binding partner(s) on the cell surface. Therefore, purified rGEP was added to Hep3B and HepG2 and cell surface binding was detected by GEP antibody (Santa Cruz). The confocal images of the cells showed rGEP (green) localized on plasma membrane (red) (Figure 2A). Besides, detached HCC cells were incubated with purified rGEP at 4°C to quantify the rGEP binding by flow cytometry. In Figure 2B, rGEP was demonstrated to bind to both Hep3B and HepG2 from 0.4 to 3.2 µg without achieving plateau. Similar binding effects were demonstrated in Hep3B-sh1 and Huh-7 cells (data not shown). The binding of rGEP could be neutralized by preincubating the protein with GEP mAb, confirming the binding is specific (Figure 2C).
Affiliation: Department of Surgery, Centre for Cancer Research and.