TY - JOUR
T1 - Complementary cell-based high-throughput screens identify novel modulators of the unfolded protein response
AU - Fribley, Andrew M.
AU - Cruz, Patricia G.
AU - Miller, Justin R.
AU - Callaghan, Michael U.
AU - Cai, Peter
AU - Narula, Neha
AU - Neubig, Richard R.
AU - Showalter, Hollis D.
AU - Larsen, Scott D.
AU - Kirchhoff, Paul D.
AU - Larsen, Martha J.
AU - Burr, Douglas A.
AU - Schultz, Pamela J.
AU - Jacobs, Renju R.
AU - Tamayo-Castillo, Giselle
AU - Ron, David
AU - Sherman, David H.
AU - Kaufman, Randal J.
N1 - Funding Information:
Portions of this work were supported by National Institutes of Health (NIH) grants DK042394, HL052173, and HL057346, as well as MH084182 and MH089782 (R.J.K.) and DE019678 (A.M.F.). P.G.C. gratefully acknowledges the Spanish Foundation of Science and Technology (FECYT) for a postdoctoral fellowship. Additional aspects of this work were supported by NIH grant U01 TW007404 as part of the International Cooperative Biodiversity Group initiative at the Fogarty International Center (D.H.S. and G.T.-C.) and the H. W. Vahlteich Professorship (D.H.S.).
PY - 2011/9
Y1 - 2011/9
N2 - Despite advances toward understanding the prevention and treatment of many cancers, patients who suffer from oral squamous cell carcinoma (OSCC) confront a survival rate that has remained unimproved for more than 2 decades, indicating our ability to treat them pharmacologically has reached a plateau. In an ongoing effort to improve the clinical outlook for this disease, we previously reported that an essential component of the mechanism by which the proteasome inhibitor bortezomib (PS-341, Velcade) induced apoptosis in OSCC required the activation of a terminal unfolded protein response (UPR). Predicated on these studies, the authors hypothesized that high-throughput screening (HTs) of large diverse chemical libraries might identify more potent or selective small-molecule activators of the apoptotic arm of the UPR to control or kill OSCC. They have developed complementary cell-based assays using stably transfected CHO-K1 cell lines that individually assess the PERK/eIF2α/CHOP (apoptotic) or the IRE1/XBP1 (adaptive) UPR subpathways. An ∼66 K compound collection was screened at the University of michigan Center for Chemical Genomics that included a unique library of prefractionated natural product extracts. The mycotoxin methoxycitrinin was isolated from a natural extract and found to selectively activate the CHOP-luciferase reporter at 80 μM. A series of citrinin derivatives was isolated from these extracts, including a unique congener that has not been previously described. In an effort to identify more potent compounds, the authors examined the ability of citrinin and the structurally related mycotoxins ochratoxin A and patulin to activate the UPR. strikingly, it was found that patulin at 2.5 to 10 μM induced a terminal UPR in a panel of OSCC cells that was characterized by an increase in CHOP, GADD34, and ATF3 gene expression and XBP1 splicing. A luminescent caspase assay and the induction of several BH3-only genes indicated that patulin could induce apoptosis in OSCC cells. These data support the use of this complementary HTS strategy to identify novel modulators of UPR signaling and tumor cell death.
AB - Despite advances toward understanding the prevention and treatment of many cancers, patients who suffer from oral squamous cell carcinoma (OSCC) confront a survival rate that has remained unimproved for more than 2 decades, indicating our ability to treat them pharmacologically has reached a plateau. In an ongoing effort to improve the clinical outlook for this disease, we previously reported that an essential component of the mechanism by which the proteasome inhibitor bortezomib (PS-341, Velcade) induced apoptosis in OSCC required the activation of a terminal unfolded protein response (UPR). Predicated on these studies, the authors hypothesized that high-throughput screening (HTs) of large diverse chemical libraries might identify more potent or selective small-molecule activators of the apoptotic arm of the UPR to control or kill OSCC. They have developed complementary cell-based assays using stably transfected CHO-K1 cell lines that individually assess the PERK/eIF2α/CHOP (apoptotic) or the IRE1/XBP1 (adaptive) UPR subpathways. An ∼66 K compound collection was screened at the University of michigan Center for Chemical Genomics that included a unique library of prefractionated natural product extracts. The mycotoxin methoxycitrinin was isolated from a natural extract and found to selectively activate the CHOP-luciferase reporter at 80 μM. A series of citrinin derivatives was isolated from these extracts, including a unique congener that has not been previously described. In an effort to identify more potent compounds, the authors examined the ability of citrinin and the structurally related mycotoxins ochratoxin A and patulin to activate the UPR. strikingly, it was found that patulin at 2.5 to 10 μM induced a terminal UPR in a panel of OSCC cells that was characterized by an increase in CHOP, GADD34, and ATF3 gene expression and XBP1 splicing. A luminescent caspase assay and the induction of several BH3-only genes indicated that patulin could induce apoptosis in OSCC cells. These data support the use of this complementary HTS strategy to identify novel modulators of UPR signaling and tumor cell death.
KW - Cell-based assay
KW - Endoplasmic reticulum stress
KW - Luciferase reporter
KW - Natural products
KW - Unfolded protein response
UR - http://www.scopus.com/inward/record.url?scp=80054758767&partnerID=8YFLogxK
U2 - 10.1177/1087057111414893
DO - 10.1177/1087057111414893
M3 - Article
C2 - 21844328
AN - SCOPUS:80054758767
VL - 16
SP - 825
EP - 835
JO - Journal of Biomolecular Screening
JF - Journal of Biomolecular Screening
SN - 1087-0571
IS - 8
ER -