Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history

Sung Hoon Kim, Zeynep Madak-Erdogan, Sung Chul Bae, Kathryn E. Carlson, Christopher G. Mayne, Steve Granick, Benita S Katzenellenbogen, John A. Katzenellenbogen

Research output: Contribution to journalArticle

Abstract

Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells. In response to pH changes, however, these estrogen-dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR-PAMAM revealed high ligand shielding above pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand-PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol- and diphenolic acid-PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen-dendrimer conjugates appears to be metastable. This pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.

Original languageEnglish (US)
Pages (from-to)10326-10335
Number of pages10
JournalJournal of the American Chemical Society
Volume137
Issue number32
DOIs
StatePublished - Aug 19 2015

Fingerprint

Dendrimers
bioactivity
Hormones
Bioactivity
accessibility
ligand
hormone
Estrogens
History
Ligands
history
Shielding
Bearings (structural)
acid
nuclear magnetic resonance
Fluorescence Polarization
Acids
Fluorophores
Drug Design
Endosomes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Kim, S. H., Madak-Erdogan, Z., Bae, S. C., Carlson, K. E., Mayne, C. G., Granick, S., ... Katzenellenbogen, J. A. (2015). Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history. Journal of the American Chemical Society, 137(32), 10326-10335. https://doi.org/10.1021/jacs.5b05952

Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history. / Kim, Sung Hoon; Madak-Erdogan, Zeynep; Bae, Sung Chul; Carlson, Kathryn E.; Mayne, Christopher G.; Granick, Steve; Katzenellenbogen, Benita S; Katzenellenbogen, John A.

In: Journal of the American Chemical Society, Vol. 137, No. 32, 19.08.2015, p. 10326-10335.

Research output: Contribution to journalArticle

Kim, Sung Hoon ; Madak-Erdogan, Zeynep ; Bae, Sung Chul ; Carlson, Kathryn E. ; Mayne, Christopher G. ; Granick, Steve ; Katzenellenbogen, Benita S ; Katzenellenbogen, John A. / Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history. In: Journal of the American Chemical Society. 2015 ; Vol. 137, No. 32. pp. 10326-10335.
@article{73802d5bc40e4123aa4cd3020d9f66f3,
title = "Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history",
abstract = "Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells. In response to pH changes, however, these estrogen-dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR-PAMAM revealed high ligand shielding above pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand-PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol- and diphenolic acid-PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen-dendrimer conjugates appears to be metastable. This pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.",
author = "Kim, {Sung Hoon} and Zeynep Madak-Erdogan and Bae, {Sung Chul} and Carlson, {Kathryn E.} and Mayne, {Christopher G.} and Steve Granick and Katzenellenbogen, {Benita S} and Katzenellenbogen, {John A.}",
year = "2015",
month = "8",
day = "19",
doi = "10.1021/jacs.5b05952",
language = "English (US)",
volume = "137",
pages = "10326--10335",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "32",

}

TY - JOUR

T1 - Ligand accessibility and bioactivity of a hormone-dendrimer conjugate depend on pH and pH history

AU - Kim, Sung Hoon

AU - Madak-Erdogan, Zeynep

AU - Bae, Sung Chul

AU - Carlson, Kathryn E.

AU - Mayne, Christopher G.

AU - Granick, Steve

AU - Katzenellenbogen, Benita S

AU - Katzenellenbogen, John A.

PY - 2015/8/19

Y1 - 2015/8/19

N2 - Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells. In response to pH changes, however, these estrogen-dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR-PAMAM revealed high ligand shielding above pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand-PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol- and diphenolic acid-PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen-dendrimer conjugates appears to be metastable. This pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.

AB - Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells. In response to pH changes, however, these estrogen-dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR-PAMAM revealed high ligand shielding above pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand-PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol- and diphenolic acid-PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen-dendrimer conjugates appears to be metastable. This pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.

UR - http://www.scopus.com/inward/record.url?scp=84939865433&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84939865433&partnerID=8YFLogxK

U2 - 10.1021/jacs.5b05952

DO - 10.1021/jacs.5b05952

M3 - Article

C2 - 26186415

AN - SCOPUS:84939865433

VL - 137

SP - 10326

EP - 10335

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 32

ER -