Novel antiproliferative tripeptides block AP-1 transcriptional complex by in silico approach

BACKGROUNDThe complexity and heterogeneity at genetic, epigenetic and microenvironment levels are key attributes of tumors. Genetic heterogeneity encompasses one of key factors at transcriptional gene regulation that promote abnormal proliferation, invasiveness and metastasis. Among various key pro-tumor transcriptional complexes, activating protein-1 (AP-1) transcriptional complex controls the transcriptional expression of key oncogenes in cancer cells. Therefore, an avenue to search for a chemical inhibition approach of the AP-1 transcriptional complex is warranted in cancer therapeutics. METHODSTo achieve chemical inhibition of AP-1 transcriptional complex, we report novel tripeptides identified from the goat urine DMSO fraction as potential agents that bind to AP-1 responsive TPA element and heterodimer c-Jun:c-Fos. Novel tripeptides enriched GUDF were tested against DNA substrates to assess DNA metabolizing activity. Further, Novel tripeptides enriched GUDF were treated upon HCT-116 cells to estimate the nature of tripeptides entered into the intracellular compartment of HCT-116 cells. Here, we report on a novel methodology that employ VTGE assisted intracellular metabolite purification and is analyzed with the help of LC-HRMS technique. Post purification of intracellular metabolites that included tripeptides of GUDF, these tripeptides from DMSO and GUDF treated HCT-116 cells were subjected to molecular docking and ligand-DNA:AP-1 (PDB ID: 1FOS) interaction study by using bioinformatics tools AutoDock Vina and PyMol. RESULTSGUDF enriched with tripeptides and other metabolites show appreciable instability of DNA substrates plasmid and genomic DNA to an extent of 90%. Interestingly, LC-HRMS analysis of intracellular metabolite profiling of GUDF treated HCT-116 cells reveal the appreciable abundance of tripeptides Glu-Glu-Arg, Gly-Arg-Pro, Gln-Lys-Arg, Glu-Glu-Lys, Trp-Trp-Val. On the other hand, DMSO treated HCT-116 cells show the presence of Ser-Trp-Lys, Glu-Glu-Gln, Glu-Glu-Lys, Ser-Leu-Ser. Interestingly, GUDF treated HCT-116 cells show inhibition of proliferation by more than 70%. Among the identified intracellular tripeptides, Glu-Glu-Arg (9.1 Kcal/Mol), Gly-Arg-Pro (8.8 Kcal/Mol), and Gln-Lys-Arg (6.8) show a precise and strong binding to heptameric TPA response element 5 TGAGTCA 3 and key amino acid residue within the AP-1 transcriptional complex. CONCLUSIONIn summary, this study suggests the potential of novel tripeptides, those are reported from GUDF intracellularly in HCT-116 cells to destabilize the AP-1 transcriptional complex. Data indicate that cellular arrest in HCT-116 cells treated by GUDF is well supported by the molecular docking observations that destabilization of AP-1 complex is linked to reduced growth and proliferation.