Novel Antiproliferative Tripeptides Inhibit AP-1 Transcriptional Complex

Among pro-tumor transcriptional complexes, activating protein-1 (AP-1) controls the expression of key oncogenes in cancer. Therefore, avenues for chemical inhibition approach of the AP-1 transcriptional complex are warranted in cancer therapeutics. The biological role of novel tripeptides enriched goat urine DMSO fraction (GUDF) were evaluated by in vitro DNA damage and cell-based assays. Tripeptides enriched GUDF were treated upon HCT-116 cells to estimate the nature of intracellular tripeptides that are responsible for antiproliferative effects. Here, we report a novel vertical tube gel electrophoresis (VTGE) assisted intracellular metabolite purification assay. Identified tripeptides were subjected to molecular docking and simulation to evaluate inhibitory role upon AP-1 (c-Jun:c-Fos:DNA) complex. GUDF enriched with tripeptides showed appreciable DNA instability up to 90% and 70% proliferation arrest in HCT-116 cells. LC-HRMS analysis of intracellular metabolites of GUDF treated HCT-116 cells revealed the abundance of tripeptides such as Glu-Glu-Arg, Gly-Arg-Pro, Gln-Lys-Arg, Glu-Glu-Lys, Trp-Trp-Val. Among the identified intracellular tripeptides, Glu-Glu-Arg (− 9.1 kcal/mol) showed strong binding to AP-1 response element specifically heptamer 5′TGAGTCA3′. Tripeptide Glu-Glu-Arg displayed significant fluctuations with RMSF 13.6 A which is about 3 times more than the control within the AP-1 response element. This study reports on a novel tripeptide Glu-Glu-Arg in the intracellular compartment of HCT-116 cells treated by GUDF. Here, proliferation arrest in HCT-116 cells is well supported by the molecular docking and simulation data that strongly suggest the ability of Glu-Glu-Arg to inhibit AP-1 complex. In future, biological relevance of Glu-Glu-Arg may be explored as an anticancer candidate.