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: rGEP fused with C-terminal HIS-tag was expressed from a stable clone of pSecTag2/Hygro-rGEP transfected COS-1. Secreted rGEP was collected from the medium and purified to ho mogeneity. Molecular weights of rGEP were estimated to ~90 and 70 kDa, respectively, before and after the cleavage of the N-glycan (Figure 1A; Supplementary Figure S1, available at Carcinogenesis Online). A range of 0.1–0.4 µg/ml rGEP was found to trigger ph osphorylation of AKT and ERK1/2 in HepG2 and Hep3B-sh1 cells dose dependently (Figure 1B; Supplementary Figure S2, available at Carcinogenesis Online). These activations could be counteracted by pretreating the cells with PI3K inhibitor wortmannin and MEK inhibitor U0126 (Figure 1B). The activation of intracellular signaling pathways implicated that the rGEP is biologically functional and these signaling pathways maybe regulated through cell surface-binding partner of GEP.
Affiliation: Department of Surgery, Centre for Cancer Research and.