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Modulation of the unfolded protein response impedes tumor cell adaptation to proteotoxic stress: a PERK for hepatocellular carcinoma therapy.

Vandewynckel YP, Laukens D, Bogaerts E, Paridaens A, Van den Bussche A, Verhelst X, Van Steenkiste C, Descamps B, Vanhove C, Libbrecht L, De Rycke R, Lambrecht BN, Geerts A, Janssens S, Van Vlierberghe H - Hepatol Int (2014)

Bottom Line: Consistent with the UPR activation, electron microscopy demonstrated ER expansion and reorganization in HCC cells in vivo.Strikingly, under ER stress or hypoxia, the Perk inhibitor and not the Ire1 inhibitor reduced cell viability and proliferation via escalating proteotoxic stress in vitro.We provide the first evaluation of the UPR dynamics in a long-term cancer model and identified a small molecule inhibitor of Perk as a promising strategy for HCC therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Hepatology and Gastroenterology, Ghent University, De Pintelaan 185, 1K12 IE, 9000 Ghent, Belgium.

ABSTRACT

Background: Functional disturbances of the endoplasmic reticulum (ER) lead to activation of the unfolded protein response (UPR), which is involved in the consecutive steps of carcinogenesis. In human hepatocellular carcinoma (HCC), the UPR is shown to be activated; however, little is known about the UPR kinetics and effects of UPR modulation in HCC.

Methods: We sequentially monitored the UPR over time in an orthotopic mouse model for HCC and explored the effects of UPR modulation on cell viability and proliferation in vitro and in the mouse model.

Results: The expression of ER-resident chaperones peaked during tumor initiation and increased further during tumor progression, predominantly within the nodules. A peak in Ire1 signaling was observed during tumor initiation. The Perk pathway was activated during tumor progression, and the proapoptotic target Chop was upregulated from week 5 and continued to rise, especially in the tumors. The Atf6 pathway was modestly activated only after tumor initiation. Consistent with the UPR activation, electron microscopy demonstrated ER expansion and reorganization in HCC cells in vivo. Strikingly, under ER stress or hypoxia, the Perk inhibitor and not the Ire1 inhibitor reduced cell viability and proliferation via escalating proteotoxic stress in vitro. Notably, the Perk inhibitor significantly decreased tumor burden in the mouse model.

Conclusion: We provide the first evaluation of the UPR dynamics in a long-term cancer model and identified a small molecule inhibitor of Perk as a promising strategy for HCC therapy.

No MeSH data available.


Related in: MedlinePlus

A PERK inhibitor reduces HCC burden in the orthotopic mouse model. a Immunoblotting for phospho-Perk, Atf4 and phospho-eIf2α in the lysates of isolated tumors after 25 weeks of DEN followed by treatment with a PERK inhibitor or vehicle. Experiments were repeated twice with similar results. b Reticulin staining to quantify the tumor burden as shown by mean total tumor surface. Arrows indicate tumors. c18F-Choline positron emission tomography visualizes cell membrane synthesis after the indicated treatments. Arrows indicate the left kidney for reference density. Standardized uptake values of the mouse livers are presented as the mean ± SD. One-way ANOVA was applied for statistical analysis. *p < 0.05, **p < 0.01
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Fig5: A PERK inhibitor reduces HCC burden in the orthotopic mouse model. a Immunoblotting for phospho-Perk, Atf4 and phospho-eIf2α in the lysates of isolated tumors after 25 weeks of DEN followed by treatment with a PERK inhibitor or vehicle. Experiments were repeated twice with similar results. b Reticulin staining to quantify the tumor burden as shown by mean total tumor surface. Arrows indicate tumors. c18F-Choline positron emission tomography visualizes cell membrane synthesis after the indicated treatments. Arrows indicate the left kidney for reference density. Standardized uptake values of the mouse livers are presented as the mean ± SD. One-way ANOVA was applied for statistical analysis. *p < 0.05, **p < 0.01

Mentions: PERKi reduced PERK autophosphorylation in DEN-induced HCC, validating the in vivo activity of the small molecule used. Atf4 expression and eIf2α phosphorylation were only slightly reduced (Fig. 5a).Fig. 5


Modulation of the unfolded protein response impedes tumor cell adaptation to proteotoxic stress: a PERK for hepatocellular carcinoma therapy.

Vandewynckel YP, Laukens D, Bogaerts E, Paridaens A, Van den Bussche A, Verhelst X, Van Steenkiste C, Descamps B, Vanhove C, Libbrecht L, De Rycke R, Lambrecht BN, Geerts A, Janssens S, Van Vlierberghe H - Hepatol Int (2014)

A PERK inhibitor reduces HCC burden in the orthotopic mouse model. a Immunoblotting for phospho-Perk, Atf4 and phospho-eIf2α in the lysates of isolated tumors after 25 weeks of DEN followed by treatment with a PERK inhibitor or vehicle. Experiments were repeated twice with similar results. b Reticulin staining to quantify the tumor burden as shown by mean total tumor surface. Arrows indicate tumors. c18F-Choline positron emission tomography visualizes cell membrane synthesis after the indicated treatments. Arrows indicate the left kidney for reference density. Standardized uptake values of the mouse livers are presented as the mean ± SD. One-way ANOVA was applied for statistical analysis. *p < 0.05, **p < 0.01
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Related In: Results  -  Collection

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Fig5: A PERK inhibitor reduces HCC burden in the orthotopic mouse model. a Immunoblotting for phospho-Perk, Atf4 and phospho-eIf2α in the lysates of isolated tumors after 25 weeks of DEN followed by treatment with a PERK inhibitor or vehicle. Experiments were repeated twice with similar results. b Reticulin staining to quantify the tumor burden as shown by mean total tumor surface. Arrows indicate tumors. c18F-Choline positron emission tomography visualizes cell membrane synthesis after the indicated treatments. Arrows indicate the left kidney for reference density. Standardized uptake values of the mouse livers are presented as the mean ± SD. One-way ANOVA was applied for statistical analysis. *p < 0.05, **p < 0.01
Mentions: PERKi reduced PERK autophosphorylation in DEN-induced HCC, validating the in vivo activity of the small molecule used. Atf4 expression and eIf2α phosphorylation were only slightly reduced (Fig. 5a).Fig. 5

Bottom Line: Consistent with the UPR activation, electron microscopy demonstrated ER expansion and reorganization in HCC cells in vivo.Strikingly, under ER stress or hypoxia, the Perk inhibitor and not the Ire1 inhibitor reduced cell viability and proliferation via escalating proteotoxic stress in vitro.We provide the first evaluation of the UPR dynamics in a long-term cancer model and identified a small molecule inhibitor of Perk as a promising strategy for HCC therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Hepatology and Gastroenterology, Ghent University, De Pintelaan 185, 1K12 IE, 9000 Ghent, Belgium.

ABSTRACT

Background: Functional disturbances of the endoplasmic reticulum (ER) lead to activation of the unfolded protein response (UPR), which is involved in the consecutive steps of carcinogenesis. In human hepatocellular carcinoma (HCC), the UPR is shown to be activated; however, little is known about the UPR kinetics and effects of UPR modulation in HCC.

Methods: We sequentially monitored the UPR over time in an orthotopic mouse model for HCC and explored the effects of UPR modulation on cell viability and proliferation in vitro and in the mouse model.

Results: The expression of ER-resident chaperones peaked during tumor initiation and increased further during tumor progression, predominantly within the nodules. A peak in Ire1 signaling was observed during tumor initiation. The Perk pathway was activated during tumor progression, and the proapoptotic target Chop was upregulated from week 5 and continued to rise, especially in the tumors. The Atf6 pathway was modestly activated only after tumor initiation. Consistent with the UPR activation, electron microscopy demonstrated ER expansion and reorganization in HCC cells in vivo. Strikingly, under ER stress or hypoxia, the Perk inhibitor and not the Ire1 inhibitor reduced cell viability and proliferation via escalating proteotoxic stress in vitro. Notably, the Perk inhibitor significantly decreased tumor burden in the mouse model.

Conclusion: We provide the first evaluation of the UPR dynamics in a long-term cancer model and identified a small molecule inhibitor of Perk as a promising strategy for HCC therapy.

No MeSH data available.


Related in: MedlinePlus