The neutralization of the inhibitory effect of EGCG on cancer cell growth by peptides deduced from the extracellular domain of 67LR.

<p>After pre-incubation of EGCG (1 µM) with each peptide (1 µM): (A) 20-amino acid segment peptides, (B) 10-amino acid segment peptides, or (C) 9-amino acid segment peptides (single amino acid deletion form of the N- or C-terminus of the peptide LR 161-170), the 67LR-overexpressed HepG2 cells were treated with these mixtures for 5 days and the cell number was assessed. The results, EGCG plus peptide (closed bar), are shown as the relative cell number to the EGCG-nontreated control (open bar), and the data presented are the means ± S.D. (n = 3) (Student’s <i>t</i>-test, *, <i>p</i><0.05, **, <i>p</i><0.01, ***, <i>p</i><0.001). D) SDS-PAGE of recombinant LR (r-hLR_102-295 and the mutant r-hLR_102-295Δ161-171 expressed in <i>E. coli</i>). The lanes of Wild and Δ161-171 are the wild-type r-hLR_102-295 and the mutant r-hLR_102-295Δ161-171, respectively. Molecular mass markers (in kDa) are indicated at the left. E) Western blot analysis of the recombinant LR was performed by using the anti-LR antibody F18. F) The effect of r-hLR_102-295 and the mutant r-hLR_102-295Δ161-170 on the cancer cell growth inhibition by EGCG. After incubation of each r-hLR protein or LR161-170 peptide with or without EGCG, HepG2 cells were treated with these mixtures for 5 days and the cell number was assessed. The results are shown as the relative cell number of EGCG-, EGCG plus LR peptide-, or EGCG plus LR protein-treated cells (closed bar) to the EGCG-nontreated control cells (open bar) under each mixture condition (none, LR peptide, or LR protein), and the data presented are the means ± S.D. (n = 3) (Student’s <i>t</i>-test, ***, <i>p</i><0.001).