Elucidation of the anticancer potential and tubulin isotype-specific interactions of β-sitosterol. Issue 1 (2nd January 2018)

• Record Type: Journal Article
• Authors: Pradhan, Madhura; Suri, Charu; Choudhary, Sinjan; Naik, Pradeep Kumar; Lopus, Manu
• Is Part Of: Journal of biomolecular structure & dynamics. Volume 36:Issue 1(2018)
• Page Start: 195
• Page End: 208
• Publication Date: 2018-01-02
• Subjects: β-sitosterol -- molecular dynamic simulations -- breast cancer -- microtubule -- β-tubulin isotypes; Biomolecules -- Periodicals; Molecular structure -- Periodicals; Molecular Biology -- Periodicals; Biomechanics -- Periodicals; 572
• DOI: 10.1080/07391102.2016.1271749
• Languages: English
• ISSNs: 0739-1102

Abstract

Abstract : Beta-sitosterol (β-SITO), a phytosterol present in many edible vegetables, has been reported to possess antineoplastic properties and cancer treatment potential. We have shown previously that it binds at a unique site (the 'SITO-site') compared to the colchicine binding site at the interface of α- and β-tubulin. In this study, we investigated the anticancer efficacy of β-SITO against invasive breast carcinoma using MCF-7 cells. Since 'isotypes' of β-tubulin show tissue-specific expression and many are associated with cancer drug resistance, using computer-assisted docking and atomistic molecular dynamic simulations, we also examined its binding interactions to all known isotypes of β-tubulin in αβ-tubulin dimer. β-SITO inhibited MCF-7 cell viability by up to 50%, compared to vehicle-treated control cells. Indicating its antimetastatic potential, the phytosterol strongly inhibited cell migration. Immunofluorescence imaging of β-SITO-treated MCF-7 cells exhibited disruption of the microtubules and chromosome organization. Far-UV circular dichroism spectra indicated loss of helical stability in tubulin when bound to β-SITO. Docking and MD simulation studies, combined with MM-PBSA and MM-GBSA calculations revealed that β-SITO preferentially binds with specific β-tubulin isotypes (βII and βIII ) in the αβ-tubulin dimer. Both these β-tubulin isotypes have been implicated in drug resistance against tubulin-targeted chemotherapeutics. Our data show the tubulin-targeted anticancer potential of β-SITO, and its potential clinical utility against βII and βIII isotype-overexpressing neoplasms.