Green tea polyphenol EGCG sensing motif on the 67-kDa laminin receptor.
BACKGROUND
We previously identified the 67-kDa laminin receptor (67LR) as the cell-surface receptor conferring the major green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) responsiveness to cancer cells. However, the underlying mechanism for interaction between EGCG and 67LR remains unclear. In this study, we investigated the possible role of EGCG-67LR interaction responsible for its bioactivities.


RESULTS
We synthesized various peptides deduced from the extracellular domain corresponding to the 102-295 region of human 67LR encoding a 295-amino acid. The neutralizing activity of these peptides toward EGCG cell-surface binding and inhibition of cancer cell growth were assayed. Both activities were inhibited by a peptide containing the 10-amino acid residues, IPCNNKGAHS, corresponding to residues 161-170. Furthermore, mass spectrometric analysis revealed the formation of a EGCG-LR161-170 peptide complex. A study of the amino acid deletion/replacement of the peptide LR161-170 indicated that the 10-amino acid length and two basic amino acids, K(166) and H(169), have a critical role in neutralizing EGCG's activities. Moreover, neutralizing activity against the anti-proliferation action of EGCG was observed in a recombinant protein of the extracellular domain of 67LR, and this effect was abrogated by a deletion of residues 161-170. These findings support that the 10 amino-acid sequence, IPCNNKGAHS, might be the functional domain responsible for the anti-cancer activity of EGCG.


CONCLUSIONS
Overall, our results highlight the nature of the EGCG-67LR interaction and provide novel structural insights into the understanding of 67LR-mediated functions of EGCG, and could aid in the development of potential anti-cancer compounds for chemopreventive or therapeutic uses that can mimic EGCG-67LR interactions.
Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan.
Yoshinori
Y
Fujimura
Mami
M
Sumida
Kaori
K
Sugihara
Shuntaro
S
Tsukamoto
Koji
K
Yamada
Hirofumi
H
Tachibana
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D005110:Extracellular Space / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008969:Molecular Sequence Data; D059808:Polyphenols / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017474:Receptors, Laminin / Q000737:chemistry* / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism*; D013662:Tea / Q000737:chemistry*
D059808:Polyphenols; C510624:RPSA protein, human; D017474:Receptors, Laminin; D012269:Ribosomal Proteins; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate