ABSTRACT
Poor prognosis and metastasis have been recognized as the major cause of breast cancer related deaths worldwide. Recent experimental evidence has shown that Hsp90, the prime chaperone, is overexpressed in many cancers and is responsible if reducing the 5-year survival rate of cancer patients. Therefore, targeted inhibition of Hsp90 may be a new and effective way to target cancer as well as enhancing therapeutic outcomes. In the present study, screening and simulation of potential natural compounds result in the identification of theaflavin-3-gallate as a promising inhibitory compound of Hsp90. Further in-vitro validation of the cytotoxic effect of theaflavin-3-gallate in human breast carcinoma cell line MCF7 and normal cell line MCF10A revealed that theaflavin-3-gallate significantly inhibited the cell proliferation of MCF7 cells whereas no cytotoxic effect was observed on MCF10A cells. We also found that theaflavin-3-gallate significantly induced programmed cell death by arresting cells in the G2/M phase of the cell cycle. A significant decrease in cell migration and colony formation by theaflavin-3-gallate treatment was also observed in MCF7 cells. Furthermore, theaflavin-3-gallate significantly downregulated the mRNA expression patterns of the HSP90, MMP9, VEGFA, and SPP1 genes. Collectively, our results demonstrated theaflavin-3-gallate as a potential natural Hsp90 inhibitor that can be used to enhance the therapeutic efficacy of existing breast cancer therapies and improve overall survival of breast cancer patients.
Subject(s)
Biflavonoids/pharmacology , Catechin/pharmacology , Cell Proliferation/drug effects , Gallic Acid/analogs & derivatives , HSP90 Heat-Shock Proteins/antagonists & inhibitors , Apoptosis/drug effects , Biflavonoids/chemistry , Biflavonoids/metabolism , Binding Sites , Catechin/chemistry , Catechin/metabolism , Cell Line, Tumor , DNA Damage/drug effects , Down-Regulation/drug effects , G2 Phase Cell Cycle Checkpoints/drug effects , Gallic Acid/chemistry , Gallic Acid/metabolism , Gallic Acid/pharmacology , HSP90 Heat-Shock Proteins/genetics , HSP90 Heat-Shock Proteins/metabolism , Humans , Matrix Metalloproteinase 9/genetics , Matrix Metalloproteinase 9/metabolism , Molecular Docking Simulation , Transcriptome/drug effectsABSTRACT
Heat shock protein 90 (Hsp90) is the prime molecular chaperone found to be overexpressed in cancer cells and pose as an anti-cancer therapeutic drug target for cancer chemotherapy. Even drugs are available which inhibit Hsp90, the associated side effects along with multi-drug regimen necessitate the identification of natural molecules to block the activity of Hsp90. In this present investigation, we performed virtual screening of Hsp90 inhibitors from a curated collection of natural molecules with proven pharmacological effects. This process helped in the identification of the top two scoring ligands, ginkgetin and theaflavin with favorable as well as crucial interactions with the Hsp90 ligand-binding pocket. Molecular dynamics simulations of these two natural molecules exhibited minimal fluctuations in the binding pattern of ginkgetin and theaflavin to Hsp90 which retained crucial contacts throughout the simulation time. We anticipate that ginkgetin and theaflavin could act as potent Hsp90 inhibitors which are under current investigation in our laboratory.Communicated by Ramaswamy H. Sarma.
