Simultaneous inhibition of key growth pathways in melanoma cells and tumor regression by a designed bidentate constrained helical peptide.
Protein-protein interactions are part of a large number of signaling networks and potential targets for drug development. However, discovering molecules that can specifically inhibit such interactions is a major challenge. S100B, a calcium-regulated protein, plays a crucial role in the proliferation of melanoma cells through protein-protein interactions. In this article, we report the design and development of a bidentate conformationally constrained peptide against dimeric S100B based on a natural tight-binding peptide, TRTK-12. The helical conformation of the peptide was constrained by the substitution of α-amino isobutyric acid--an amino acid having high helical propensity--in positions which do not interact with S100B. A branched bidentate version of the peptide was bound to S100B tightly with a dissociation constant of 8 nM. When conjugated to a cell-penetrating peptide, it caused growth inhibition and rapid apoptosis in melanoma cells. The molecule exerts antiproliferative action through simultaneous inhibition of key growth pathways, including reactivation of wild-type p53 and inhibition of Akt and STAT3 phosphorylation. The apoptosis induced by the bidentate constrained helix is caused by direct migration of p53 to mitochondria. At moderate intravenous dose, the peptide completely inhibits melanoma growth in a mouse model without any significant observable toxicity. The specificity was shown by lack of ability of a double mutant peptide to cause tumor regression at the same dose level. The methodology described here for direct protein-protein interaction inhibition may be effective for rapid development of inhibitors against relatively weak protein-protein interactions for de novo drug development.
Division of Structural Biology and Bioinformatics, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S.C. Mullick Road, Kolkata, 700032, West Bengal, India.
Amlanjyoti
A
Dhar
Shampa
S
Mallick
Piya
P
Ghosh
Atanu
A
Maiti
Israr
I
Ahmed
Seemana
S
Bhattacharya
Tapashi
T
Mandal
Asit
A
Manna
Koushik
K
Roy
Sandeep
S
Singh
Dipak Kumar
DK
Nayak
Paul T
PT
Wilder
Joseph
J
Markowitz
David
D
Weber
Mrinal K
MK
Ghosh
Samit
S
Chattopadhyay
Rajdeep
R
Guha
Aditya
A
Konar
Santu
S
Bandyopadhyay
Siddhartha
S
Roy
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D051347:CapZ Actin Capping Protein / Q000737:chemistry* / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival; D004195:Disease Models, Animal; D006801:Humans; D008545:Melanoma / Q000473:pathology*; D051379:Mice; D008858:Microscopy, Phase-Contrast; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012074:Remission Induction; D015398:Signal Transduction / Q000187:drug effects; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D051347:CapZ Actin Capping Protein; D010446:Peptide Fragments; C475482:TRTK-12 peptide; D016159:Tumor Suppressor Protein p53
antitumor; helix; inhibitor; peptides; protein-protein interaction