title: Tamoxifen synergizes with 4-(E)-{(4-hydroxyphenylimino)-methylbenzene, 1,2-diol} and 4-(E)-{(p-tolylimino)-methylbenzene-1,2-diol}, novel azaresveratrol analogs, in inhibiting the proliferation of breast cancer cells.
abstract: We have recently shown that 4-(E)-{(4-hydroxyphenylimino)-methylbenzene, 1,2-diol} (HPIMBD) and 4-(E)-{(p-tolylimino)-methylbenzene-1,2-diol} (TIMBD), novel analogs of resveratrol (Res), selectively inhibited the proliferation of breast cancer cells. In the current study, we tested HPIMBD and TIMBD individually in combination with tamoxifen (Tam) for inhibition of growth of breast cancer cells. Tamoxifen was first tested on non-neoplastic breast epithelial cell lines and its dose that does not inhibit their growth was determined. A combination of this low dose of Tam with either of the Res analogs HPIMBD or TIMBD, resulted in synergistic inhibition of proliferation of breast cancer cells. Both estrogen receptor (ER)-positive and negative breast cancer cell lines responded to the combination. The combination resulted in a substantial decrease in IC50 values of Res analogs in all breast cancer cell lines tested. Mechanistic studies showed a synergistic increase in apoptosis and autophagy genes (beclin-1 and LC3BII/I) with the combination in ER-negative MDA-MB-231 cells. In ER-positive MCF-7 and T47D cells, the mechanism of synergy was found to be inhibition of expression of ERα and oncogene c-Myc. The combination treatment had a synergistic effect in inhibiting the colony forming and spheroid forming ability of cancer cells. Taken together, our findings indicate that a combination of Tam and Res analogs HPIMBD or TIMBD represents a novel approach to enhancing the use of Tam in therapy for breast cancers. Considering the urgent need for novel therapeutic strategies to treat ER-negative breast cancers and overcoming resistance in ER-positive cancers, this combinatorial approach is worthy of continued investigation.
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors.forename: Amruta
authors.initials: A
authors.lastname: Ronghe
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors.forename: Anwesha
authors.initials: A
authors.lastname: Chatterjee
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors.forename: Nimee K
authors.initials: NK
authors.lastname: Bhat
authors.affiliation: Interdisciplinary Science and Technology Research Academy, Abeda Inamdar Senior College, Department of Chemistry, University of Pune, Pune, India.
authors.forename: Subhash
authors.initials: S
authors.lastname: Padhye
authors.affiliation: Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors.forename: Hari K
authors.initials: HK
authors.lastname: Bhat
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000473:pathology*; D002396:Catechols / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004357:Drug Synergism; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D000077185:Resveratrol; D012545:Schiff Bases / Q000494:pharmacology*; D013267:Stilbenes / Q000737:chemistry / Q000494:pharmacology*; D013629:Tamoxifen / Q000494:pharmacology*
chemical_list: C580935:4-((4-hydroxyphenylimino)methyl)benzene-1,2-diol; C000619336:4-(E)-((p-tolylimino)-methylbenzene-1,2-diol); D018931:Antineoplastic Agents, Hormonal; D002396:Catechols; D012545:Schiff Bases; D013267:Stilbenes; D013629:Tamoxifen; D000077185:Resveratrol
keywords: breast cancer; combination therapy; resveratrol analogs; synergistic inhibition; tamoxifen