title: Anticancer activities of pterostilbene-isothiocyanate conjugate in breast cancer cells: involvement of PPARγ.
abstract: Trans-3,5-dimethoxy-4'-hydroxystilbene (PTER), a natural dimethylated analog of resveratrol, preferentially induces certain cancer cells to undergo apoptosis and could thus have a role in cancer chemoprevention. Peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily, is a ligand-dependent transcription factor whose activation results in growth arrest and/or apoptosis in a variety of cancer cells. Here we investigated the potential of PTER-isothiocyanate (ITC) conjugate, a novel class of hybrid compound (PTER-ITC) synthesized by appending an ITC moiety to the PTER backbone, to induce apoptotic cell death in hormone-dependent (MCF-7) and -independent (MDA-MB-231) breast cancer cell lines and to elucidate PPARγ involvement in PTER-ITC action. Our results showed that when pre-treated with PPARγ antagonists or PPARγ siRNA, both breast cancer cell lines suppressed PTER-ITC-induced apoptosis, as determined by annexin V/propidium iodide staining and cleaved caspase-9 expression. Furthermore, PTER-ITC significantly increased PPARγ mRNA and protein levels in a dose-dependent manner and modulated expression of PPARγ-related genes in both breast cancer cell lines. This increase in PPARγ activity was prevented by a PPARγ-specific inhibitor, in support of our hypothesis that PTER-ITC can act as a PPARγ activator. PTER-ITC-mediated upregulation of PPARγ was counteracted by co-incubation with p38 MAPK or JNK inhibitors, suggesting involvement of these pathways in PTER-ITC action. Molecular docking analysis further suggested that PTER-ITC interacted with 5 polar and 8 non-polar residues within the PPARγ ligand-binding pocket, which are reported to be critical for its activity. Collectively, our observations suggest potential applications for PTER-ITC in breast cancer prevention and treatment through modulation of the PPARγ activation pathway.
authors.affiliation: Molecular Endocrinology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
authors.forename: Kumar
authors.initials: K
authors.lastname: Nikhil
authors.affiliation: Molecular Endocrinology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
authors.forename: Shruti
authors.initials: S
authors.lastname: Sharan
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnologia (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain.
authors.forename: Abhimanyu K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Molecular Endocrinology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
authors.forename: Ajanta
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Molecular Endocrinology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
authors.forename: Partha
authors.initials: P
authors.lastname: Roy
mesh_terms: D000704:Analysis of Variance; D017304:Annexin A5; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001391:Azo Compounds; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy*; D053453:Caspase 9 / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D017879:Isothiocyanates / Q000737:chemistry / Q000494:pharmacology; D008156:Luciferases; D061986:MCF-7 Cells; D015394:Molecular Structure; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011419:Propidium; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013267:Stilbenes / Q000737:chemistry / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D000970:Antineoplastic Agents; D001391:Azo Compounds; D017931:DNA Primers; D017879:Isothiocyanates; D047495:PPAR gamma; D013267:Stilbenes; C107773:pterostilbene; C037152:isothiocyanic acid; D011419:Propidium; D008156:Luciferases; D053453:Caspase 9; C011049:oil red O