title: Design, synthesis, and mechanistic investigations of bile acid-tamoxifen conjugates for breast cancer therapy.
abstract: We have synthesized two series of bile acid tamoxifen conjugates using three bile acids lithocholic acid (LCA), deoxycholic acid (DCA), and cholic acid (CA). These bile acid-tamoxifen conjugates possess 1, 2, and 3 tamoxifen molecules attached to hydroxyl groups of bile acids having free acid and amine functionalities at the tail region of bile acids. The in vitro anticancer activities of these bile acid-tamoxifen conjugates show that the free amine headgroup based cholic acid-tamoxifen conjugate (CA-Tam3-Am) is the most potent anticancer conjugate as compared to the parent drug tamoxifen and other acid and amine headgroup based bile acid-tamoxifen conjugates. The cholic acid-tamoxifen conjugate (CA-Tam3-Am) bearing three tamoxifen molecules shows enhanced anticancer activities in both estrogen receptor +ve and estrogen receptor -ve breast cancer cell lines. The enhanced anticancer activity of CA-Tam3-Am is due to more favorable irreversible electrostatic interactions followed by intercalation of these conjugates in hydrophobic core of membrane lipids causing increase in membrane fluidity. Annexin-FITC based FACS analysis showed that cells undergo apoptosis, and cell cycle analysis showed the arrest of cells in sub G0 phase. ROS assays showed a high amount of generation of ROS independent of ER status of the cell line indicating changes in mitochondrial membrane fluidity upon the uptake of the conjugate that further leads to the release of cytochrome c, a direct and indirect regulator of ROS. The mechanistic studies for apoptosis using PCR and western analysis showed apoptotsis by intrinsic and extrinsic pathways in ER +ve MCF-7 cells and by only an intrinsic pathway in ER -ve cells. In vivo studies in the 4T1 tumor model showed that CA-Tam3-Am is more potent than tamoxifen. These studies showed that bile acids provide a new scaffold for high drug loading and that their anticancer activities strongly depend on charge and hydrophobicity of lipid-drug conjugates.
authors.affiliation: The Laboratory of Nanotechnology and Chemical Biology, Regional Centre for Biotechnology , 180 Udyog Vihar, Phase 1, Gurgaon-122016, Haryana, India.
authors.forename: Vedagopuram
authors.initials: V
authors.lastname: Sreekanth
authors.forename: Sandhya
authors.initials: S
authors.lastname: Bansal
authors.forename: Rajender K
authors.initials: RK
authors.lastname: Motiani
authors.forename: Somanath
authors.initials: S
authors.lastname: Kundu
authors.forename: Sravan Kumar
authors.initials: SK
authors.lastname: Muppu
authors.forename: Tapodhara Datta
authors.initials: TD
authors.lastname: Majumdar
authors.forename: Kuppusamy
authors.initials: K
authors.lastname: Panjamurthy
authors.forename: Sagar
authors.initials: S
authors.lastname: Sengupta
authors.forename: Avinash
authors.initials: A
authors.lastname: Bajaj
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology / Q000627:therapeutic use*; D001647:Bile Acids and Salts / Q000737:chemistry* / Q000494:pharmacology / Q000627:therapeutic use*; D001940:Breast / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D015195:Drug Design; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D017382:Reactive Oxygen Species / Q000378:metabolism; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D001647:Bile Acids and Salts; D017382:Reactive Oxygen Species; D013629:Tamoxifen; C067536:tamoxifen acid