TY - JOUR
T1 - The fungal natural product azaphilone-9 binds to HuR and inhibits HuR-RNA interaction in vitro
AU - Kaur, Kawaljit
AU - Wu, Xiaoqing
AU - Fields, James K.
AU - Johnson, David K.
AU - Lan, Lan
AU - Pratt, Miranda
AU - Somoza, Amber D.
AU - Wang, Clay C.C.
AU - Karanicolas, John
AU - Oakley, Berl R.
AU - Xu, Liang
AU - De Guzman, Roberto N.
N1 - Publisher Copyright:
© 2017 Kaur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2017/4
Y1 - 2017/4
N2 - The RNA-binding protein Hu antigen R (HuR) binds to AU-rich elements (ARE) in the 3′-untranslated region (UTR) of target mRNAs. The HuR-ARE interactions stabilize many oncogenic mRNAs that play important roles in tumorigenesis. Thus, small molecules that interfere with the HuR-ARE interaction could potentially inhibit cancer cell growth and progression. Using a fluorescence polarization (FP) competition assay, we identified the compound azaphilone-9 (AZA-9) derived from the fungal natural product asperbenzaldehyde, binds to HuR and inhibits HuR-ARE interaction (IC 50 ∼1.2 μM). Results from surface plasmon resonance (SPR) verified the direct binding of AZA-9 to HuR. NMR methods mapped the RNA-binding interface of HuR and identified the involvement of critical RNA-binding residues in binding of AZA-9. Computational docking was then used to propose a likely binding site for AZA-9 in the RNA-binding cleft of HuR. Our results show that AZA-9 blocks key RNA-binding residues of HuR and disrupts HuR-RNA interactions in vitro. This knowledge is needed in developing more potent AZA-9 derivatives that could lead to new cancer therapy.
AB - The RNA-binding protein Hu antigen R (HuR) binds to AU-rich elements (ARE) in the 3′-untranslated region (UTR) of target mRNAs. The HuR-ARE interactions stabilize many oncogenic mRNAs that play important roles in tumorigenesis. Thus, small molecules that interfere with the HuR-ARE interaction could potentially inhibit cancer cell growth and progression. Using a fluorescence polarization (FP) competition assay, we identified the compound azaphilone-9 (AZA-9) derived from the fungal natural product asperbenzaldehyde, binds to HuR and inhibits HuR-ARE interaction (IC 50 ∼1.2 μM). Results from surface plasmon resonance (SPR) verified the direct binding of AZA-9 to HuR. NMR methods mapped the RNA-binding interface of HuR and identified the involvement of critical RNA-binding residues in binding of AZA-9. Computational docking was then used to propose a likely binding site for AZA-9 in the RNA-binding cleft of HuR. Our results show that AZA-9 blocks key RNA-binding residues of HuR and disrupts HuR-RNA interactions in vitro. This knowledge is needed in developing more potent AZA-9 derivatives that could lead to new cancer therapy.
KW - 3' Untranslated Regions/drug effects
KW - AU Rich Elements/drug effects
KW - Antigens, Surface/metabolism
KW - Benzopyrans/pharmacology
KW - Binding Sites/drug effects
KW - Biological Products/pharmacology
KW - ELAV-Like Protein 1/antagonists & inhibitors
KW - Fluorescence Polarization/methods
KW - Fungi/chemistry
KW - Humans
KW - Pigments, Biological/pharmacology
KW - Protein Binding/drug effects
KW - RNA, Messenger/metabolism
KW - RNA-Binding Proteins/metabolism
KW - RNA/metabolism
KW - Small Molecule Libraries/pharmacology
UR - http://www.scopus.com/inward/record.url?scp=85017526935&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0175471
DO - 10.1371/journal.pone.0175471
M3 - Article
C2 - 28414767
SN - 1932-6203
VL - 12
SP - e0175471
JO - PLoS ONE
JF - PLoS ONE
IS - 4
M1 - e0175471
ER -