The unfolded protein response: a novel therapeutic target for poor prognostic BRAF mutant colorectal cancer

Nicholas Forsythe, Alaa Refaat, Arman Javadi, Hajrah Khawaja, Jessica-Anne Weir, Heba Emam, Wendy L. Allen, Frank Burkamp, Vlad Popovici, Puthen V Jithesh, Claudio Isella, Melissa J. Labonte , Ian G.. Mills, Patrick G. Johnston, Sandra Van Schaeybroeck

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Abstract

BRAFV600E mutations occur in 10% of colorectal cancer (CRC) cases, are associated with poor survival and have limited responses to BRAF/MEK inhibition with or without EGFR inhibition. There is an unmet need to understand the biology of poor prognostic BRAFMT CRC. We have used differential gene expression and pathway analyses of untreated stage II and stage III BRAFMT (discovery set: n=31; validation set: n=26) CRC and an siRNA screen to characterize the biology underpinning the BRAFMT subgroup with poorest outcome. These analyses identified the unfolded protein response (UPR) as a novel and druggable pathway associated with the BRAFMT CRC subgroup with poorest outcome. We also found that oncogenic BRAF drives endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathway activation through MEK/ERK. Furthermore, inhibition of GRP78, the master regulator of the UPR, using siRNA or small molecule inhibition, resulted in acute ER stress and apoptosis, in particular in BRAFMT CRC cells. In addition, dual targeting of protein degradation using combined Carfilzomib (proteasome inhibitor) and ACY-1215 (HDAC6-selective inhibitor) treatment resulted in marked accumulation of protein aggregates, acute ER stress, apoptosis and therapeutic efficacy in BRAFMT in vitro and xenograft models. Mechanistically, we found that the apoptosis following combined Carfilzomib/ACY-1215 treatment is mediated through increased CHOP expression. Taken together, our findings indicate that oncogenic BRAF induces chronic ER stress and that inducers of acute ER stress could be a novel treatment strategy for poor prognostic BRAFMT CRC.
Original languageEnglish
JournalMolecular Cancer Therapeutics
Early online date26 Feb 2018
DOIs
Publication statusEarly online date - 26 Feb 2018

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Unfolded Protein Response
Endoplasmic Reticulum Stress
Colorectal Neoplasms
Mitogen-Activated Protein Kinase Kinases
Apoptosis
Small Interfering RNA
Therapeutics
Proteasome Inhibitors
Heat-Shock Proteins
Heterografts
Proteolysis
Gene Expression
Mutation

Keywords

  • Oncogenic BRAF, UPR, ER stress, apoptosis, colorectal cancer

Cite this

Forsythe, Nicholas ; Refaat, Alaa ; Javadi, Arman ; Khawaja, Hajrah ; Weir, Jessica-Anne ; Emam, Heba ; Allen, Wendy L. ; Burkamp, Frank ; Popovici, Vlad ; Jithesh, Puthen V ; Isella, Claudio ; Labonte , Melissa J. ; Mills, Ian G.. ; Johnston, Patrick G. ; Van Schaeybroeck, Sandra. / The unfolded protein response: a novel therapeutic target for poor prognostic BRAF mutant colorectal cancer. In: Molecular Cancer Therapeutics. 2018.
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abstract = "BRAFV600E mutations occur in 10{\%} of colorectal cancer (CRC) cases, are associated with poor survival and have limited responses to BRAF/MEK inhibition with or without EGFR inhibition. There is an unmet need to understand the biology of poor prognostic BRAFMT CRC. We have used differential gene expression and pathway analyses of untreated stage II and stage III BRAFMT (discovery set: n=31; validation set: n=26) CRC and an siRNA screen to characterize the biology underpinning the BRAFMT subgroup with poorest outcome. These analyses identified the unfolded protein response (UPR) as a novel and druggable pathway associated with the BRAFMT CRC subgroup with poorest outcome. We also found that oncogenic BRAF drives endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathway activation through MEK/ERK. Furthermore, inhibition of GRP78, the master regulator of the UPR, using siRNA or small molecule inhibition, resulted in acute ER stress and apoptosis, in particular in BRAFMT CRC cells. In addition, dual targeting of protein degradation using combined Carfilzomib (proteasome inhibitor) and ACY-1215 (HDAC6-selective inhibitor) treatment resulted in marked accumulation of protein aggregates, acute ER stress, apoptosis and therapeutic efficacy in BRAFMT in vitro and xenograft models. Mechanistically, we found that the apoptosis following combined Carfilzomib/ACY-1215 treatment is mediated through increased CHOP expression. Taken together, our findings indicate that oncogenic BRAF induces chronic ER stress and that inducers of acute ER stress could be a novel treatment strategy for poor prognostic BRAFMT CRC.",
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author = "Nicholas Forsythe and Alaa Refaat and Arman Javadi and Hajrah Khawaja and Jessica-Anne Weir and Heba Emam and Allen, {Wendy L.} and Frank Burkamp and Vlad Popovici and Jithesh, {Puthen V} and Claudio Isella and Labonte, {Melissa J.} and Mills, {Ian G..} and Johnston, {Patrick G.} and {Van Schaeybroeck}, Sandra",
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The unfolded protein response: a novel therapeutic target for poor prognostic BRAF mutant colorectal cancer. / Forsythe, Nicholas; Refaat, Alaa; Javadi, Arman; Khawaja, Hajrah; Weir, Jessica-Anne; Emam, Heba; Allen, Wendy L.; Burkamp, Frank; Popovici, Vlad; Jithesh, Puthen V; Isella, Claudio; Labonte , Melissa J.; Mills, Ian G..; Johnston, Patrick G.; Van Schaeybroeck, Sandra.

In: Molecular Cancer Therapeutics, 26.02.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The unfolded protein response: a novel therapeutic target for poor prognostic BRAF mutant colorectal cancer

AU - Forsythe, Nicholas

AU - Refaat, Alaa

AU - Javadi, Arman

AU - Khawaja, Hajrah

AU - Weir, Jessica-Anne

AU - Emam, Heba

AU - Allen, Wendy L.

AU - Burkamp, Frank

AU - Popovici, Vlad

AU - Jithesh, Puthen V

AU - Isella, Claudio

AU - Labonte , Melissa J.

AU - Mills, Ian G..

AU - Johnston, Patrick G.

AU - Van Schaeybroeck, Sandra

N1 - Copyright ©2018, American Association for Cancer Research.

PY - 2018/2/26

Y1 - 2018/2/26

N2 - BRAFV600E mutations occur in 10% of colorectal cancer (CRC) cases, are associated with poor survival and have limited responses to BRAF/MEK inhibition with or without EGFR inhibition. There is an unmet need to understand the biology of poor prognostic BRAFMT CRC. We have used differential gene expression and pathway analyses of untreated stage II and stage III BRAFMT (discovery set: n=31; validation set: n=26) CRC and an siRNA screen to characterize the biology underpinning the BRAFMT subgroup with poorest outcome. These analyses identified the unfolded protein response (UPR) as a novel and druggable pathway associated with the BRAFMT CRC subgroup with poorest outcome. We also found that oncogenic BRAF drives endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathway activation through MEK/ERK. Furthermore, inhibition of GRP78, the master regulator of the UPR, using siRNA or small molecule inhibition, resulted in acute ER stress and apoptosis, in particular in BRAFMT CRC cells. In addition, dual targeting of protein degradation using combined Carfilzomib (proteasome inhibitor) and ACY-1215 (HDAC6-selective inhibitor) treatment resulted in marked accumulation of protein aggregates, acute ER stress, apoptosis and therapeutic efficacy in BRAFMT in vitro and xenograft models. Mechanistically, we found that the apoptosis following combined Carfilzomib/ACY-1215 treatment is mediated through increased CHOP expression. Taken together, our findings indicate that oncogenic BRAF induces chronic ER stress and that inducers of acute ER stress could be a novel treatment strategy for poor prognostic BRAFMT CRC.

AB - BRAFV600E mutations occur in 10% of colorectal cancer (CRC) cases, are associated with poor survival and have limited responses to BRAF/MEK inhibition with or without EGFR inhibition. There is an unmet need to understand the biology of poor prognostic BRAFMT CRC. We have used differential gene expression and pathway analyses of untreated stage II and stage III BRAFMT (discovery set: n=31; validation set: n=26) CRC and an siRNA screen to characterize the biology underpinning the BRAFMT subgroup with poorest outcome. These analyses identified the unfolded protein response (UPR) as a novel and druggable pathway associated with the BRAFMT CRC subgroup with poorest outcome. We also found that oncogenic BRAF drives endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathway activation through MEK/ERK. Furthermore, inhibition of GRP78, the master regulator of the UPR, using siRNA or small molecule inhibition, resulted in acute ER stress and apoptosis, in particular in BRAFMT CRC cells. In addition, dual targeting of protein degradation using combined Carfilzomib (proteasome inhibitor) and ACY-1215 (HDAC6-selective inhibitor) treatment resulted in marked accumulation of protein aggregates, acute ER stress, apoptosis and therapeutic efficacy in BRAFMT in vitro and xenograft models. Mechanistically, we found that the apoptosis following combined Carfilzomib/ACY-1215 treatment is mediated through increased CHOP expression. Taken together, our findings indicate that oncogenic BRAF induces chronic ER stress and that inducers of acute ER stress could be a novel treatment strategy for poor prognostic BRAFMT CRC.

KW - Oncogenic BRAF, UPR, ER stress, apoptosis, colorectal cancer

U2 - 10.1158/1535-7163.MCT-17-0603

DO - 10.1158/1535-7163.MCT-17-0603

M3 - Article

C2 - 29483217

JO - Molecular Cancer Therapeutics

JF - Molecular Cancer Therapeutics

SN - 1535-7163

ER -