open access

Vol 51, No 4 (2013)
Review paper
Submitted: 2014-02-05
Accepted: 2014-02-05
Published online: 2014-02-05
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Crosstalk between autophagy and proteasome protein degradation systems: possible implications for cancer therapy

Slawomir Wojcik
DOI: 10.5603/FHC.2013.0036
·
Folia Histochem Cytobiol 2013;51(4):249-264.

open access

Vol 51, No 4 (2013)
REVIEW
Submitted: 2014-02-05
Accepted: 2014-02-05
Published online: 2014-02-05

Abstract

Abstract: The Ubiquitin-Proteasomes System (UPS) and autophagy, two main intracellular protein degradation pathways within the eukaryotic cells which were originally regarded as rather independent, seem to be very closely related. Proteasome inhibitors, including the multipathway inhibitor bortezomib, are drawing increased attention for their therapeutic potential in the treatment of chronic inflammation and cancer, especially tumours with a high degree of malignancy. The over-activation of autophagy induces cell death and may act as a powerful tumour-suppressing mechanism. However, autophagy, serving as an important mechanism to generate nutrients in time of cellular stresses, may directly contribute to the survival of cells treated with proteasome inhibitors, and in consequence, may decrease the effectiveness of therapy. Results of studies performed on several cancer cell lines demonstrated synergy between proteasome inhibitors and autophagy inhibitors. Those results became the base for ongoing clinical trials investigating autophagy inhibition in combination with anti-cancer therapies, including bortezomib. This review provides summary of the latest data on the functioning of the UPS and the mechanisms of autophagy. The new insights describing the main pathways of autophagy activation in response to UPS inhibition related to: (i) Unfolded Protein Response, (ii) PI3K/Akt/mTOR pathway, and (iii) formation of aggresomes, are discussed. It is concluded that concomitant inhibition of the two main cellular protein degradation systems may provide new therapeutic modalities for cancer treatment.

Abstract

Abstract: The Ubiquitin-Proteasomes System (UPS) and autophagy, two main intracellular protein degradation pathways within the eukaryotic cells which were originally regarded as rather independent, seem to be very closely related. Proteasome inhibitors, including the multipathway inhibitor bortezomib, are drawing increased attention for their therapeutic potential in the treatment of chronic inflammation and cancer, especially tumours with a high degree of malignancy. The over-activation of autophagy induces cell death and may act as a powerful tumour-suppressing mechanism. However, autophagy, serving as an important mechanism to generate nutrients in time of cellular stresses, may directly contribute to the survival of cells treated with proteasome inhibitors, and in consequence, may decrease the effectiveness of therapy. Results of studies performed on several cancer cell lines demonstrated synergy between proteasome inhibitors and autophagy inhibitors. Those results became the base for ongoing clinical trials investigating autophagy inhibition in combination with anti-cancer therapies, including bortezomib. This review provides summary of the latest data on the functioning of the UPS and the mechanisms of autophagy. The new insights describing the main pathways of autophagy activation in response to UPS inhibition related to: (i) Unfolded Protein Response, (ii) PI3K/Akt/mTOR pathway, and (iii) formation of aggresomes, are discussed. It is concluded that concomitant inhibition of the two main cellular protein degradation systems may provide new therapeutic modalities for cancer treatment.
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Keywords

autophagy; Ubiquitin-Proteasomes System; proteasome inhibitors; cancer; Unfolded Protein Response; mTOR; LC3; ATF4; aggresomes

About this article
Title

Crosstalk between autophagy and proteasome protein degradation systems: possible implications for cancer therapy

Journal

Folia Histochemica et Cytobiologica

Issue

Vol 51, No 4 (2013)

Article type

Review paper

Pages

249-264

Published online

2014-02-05

DOI

10.5603/FHC.2013.0036

Bibliographic record

Folia Histochem Cytobiol 2013;51(4):249-264.

Keywords

autophagy
Ubiquitin-Proteasomes System
proteasome inhibitors
cancer
Unfolded Protein Response
mTOR
LC3
ATF4
aggresomes

Authors

Slawomir Wojcik

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