The Proteasome-associated deubiquitinase UCHL5/UBH-4 in proteasome modulation and as a prognostic marker in gastrointestinal cancers

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

The ubiquitin-proteasome system (UPS) is the major cellular pathway for controlled protein degradation, and, together with the autophagy-lysosome pathway, it is a central player in maintaining protein homeostasis. The catalytic core of the UPS is the proteasome, a complex holoenzyme composed of multiple different subunits with varying functions. Disruptions in the UPS are associated with many pathological conditions, including aging-related neurological diseases (such as Alzheimer's, Parkinson's, or Huntington's disease), as well as different cancers. Proteasome inhibitors (e.g. Bortezomib) are in use as cancer therapeutics (e.g. in refractory multiple myeloma and mantle cell lymphoma), but dose-limiting toxicities, drug-resistance and other adverse side-effects have created an acute need for identifying alternative targets that modulate the UPS. Yet, despite its wide-ranging importance, it remains to be defined how UPS is regulated, especially in vivo. The purpose of this thesis was to provide new information on UPS modulation in a living, multicellular organism, with the help of the model organism Caenorhabditis elegans. Further, the aim was to investigate the potential role of an identified proteasome regulator UCHL5/UBH-4 as a biomarker in three gastrointestinal cancers: colorectal cancer (CRC), gastric cancer (GC) and pancreatic ductal adenocarcinoma (PDAC). In the first part of the study, it was established that UCHL5/UBH-4, a proteasome-associated deubiquitinating enzyme (DUB), modulates proteasome activity in C. elegans, and additionally increases the degradation of proteotoxic proteins in human cancer cells. In C. elegans, UBH-4 expression was demonstrated to be regulated by the ageing-regulating Insulin/IGF-1 signaling (IIS) pathway through the transcription factor DAF-16 in a tissue-specific manner. Further, minor knockdown of ubh-4 resulted in a short lifespan extension without affecting progeny amounts. In the second part of the study, the role of UCHL5 was investigated in various gastrointestinal cancers. UCHL5 tumorexpression was scored with immunohistochemistry from representative patient tumor samples in CRC, GC and PDAC. UCHL5-immunoexpression correlated with increased survival in the subgroup of patients with lymph node-positive (Dukes C/stage III) rectal cancer. In addition, both positive nuclear and high cytoplasmic UCHL5-immunoexpression associated with better prognosis in PDAC. Positive UCHL5-immunoexpression was also linked to enhanced survival in the subgroups of gastric cancer patients with small tumors (
Original languageEnglish
Award date2 Mar 2018
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-51-4016-6
Electronic ISBNs978-951-51-4017-3
Publication statusPublished - 2018
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 3111 Biomedicine
  • 3122 Cancers

Cite this

@phdthesis{6ef8b10bf2c04d9bbd4aeb68cad675d7,
title = "The Proteasome-associated deubiquitinase UCHL5/UBH-4 in proteasome modulation and as a prognostic marker in gastrointestinal cancers",
abstract = "The ubiquitin-proteasome system (UPS) is the major cellular pathway for controlled protein degradation, and, together with the autophagy-lysosome pathway, it is a central player in maintaining protein homeostasis. The catalytic core of the UPS is the proteasome, a complex holoenzyme composed of multiple different subunits with varying functions. Disruptions in the UPS are associated with many pathological conditions, including aging-related neurological diseases (such as Alzheimer's, Parkinson's, or Huntington's disease), as well as different cancers. Proteasome inhibitors (e.g. Bortezomib) are in use as cancer therapeutics (e.g. in refractory multiple myeloma and mantle cell lymphoma), but dose-limiting toxicities, drug-resistance and other adverse side-effects have created an acute need for identifying alternative targets that modulate the UPS. Yet, despite its wide-ranging importance, it remains to be defined how UPS is regulated, especially in vivo. The purpose of this thesis was to provide new information on UPS modulation in a living, multicellular organism, with the help of the model organism Caenorhabditis elegans. Further, the aim was to investigate the potential role of an identified proteasome regulator UCHL5/UBH-4 as a biomarker in three gastrointestinal cancers: colorectal cancer (CRC), gastric cancer (GC) and pancreatic ductal adenocarcinoma (PDAC). In the first part of the study, it was established that UCHL5/UBH-4, a proteasome-associated deubiquitinating enzyme (DUB), modulates proteasome activity in C. elegans, and additionally increases the degradation of proteotoxic proteins in human cancer cells. In C. elegans, UBH-4 expression was demonstrated to be regulated by the ageing-regulating Insulin/IGF-1 signaling (IIS) pathway through the transcription factor DAF-16 in a tissue-specific manner. Further, minor knockdown of ubh-4 resulted in a short lifespan extension without affecting progeny amounts. In the second part of the study, the role of UCHL5 was investigated in various gastrointestinal cancers. UCHL5 tumorexpression was scored with immunohistochemistry from representative patient tumor samples in CRC, GC and PDAC. UCHL5-immunoexpression correlated with increased survival in the subgroup of patients with lymph node-positive (Dukes C/stage III) rectal cancer. In addition, both positive nuclear and high cytoplasmic UCHL5-immunoexpression associated with better prognosis in PDAC. Positive UCHL5-immunoexpression was also linked to enhanced survival in the subgroups of gastric cancer patients with small tumors (",
keywords = "Adenocarcinoma, Biomarkers, Tumor, Caenorhabditis elegans, Carcinoma, Pancreatic Ductal, Colorectal Neoplasms, Deubiquitinating Enzymes, Disease-Free Survival, Gene Expression Regulation, Neoplastic, Insulin, Insulin-Like Growth Factor I, Lymphatic Metastasis, Neoplasm Staging, Prognosis, Proteasome Endopeptidase Complex, +metabolism, Signal Transduction, Stomach Neoplasms, Transcription Factors, +genetics, Ubiquitin Thiolesterase, +biosynthesis, 3111 Biomedicine, 3122 Cancers",
author = "Leena Arpalahti",
note = "M1 - 120 s.",
year = "2018",
language = "English",
isbn = "978-951-51-4016-6",
series = "Dissertationes Scholae Doctoralis Ad Sanitatem Investigandam Universitatis Helsinkiensis",
publisher = "Helsingin yliopisto",
number = "11/2018",
address = "Finland",

}

The Proteasome-associated deubiquitinase UCHL5/UBH-4 in proteasome modulation and as a prognostic marker in gastrointestinal cancers. / Arpalahti, Leena.

Helsinki : Helsingin yliopisto, 2018. 120 p.

Research output: ThesisDoctoral ThesisCollection of Articles

TY - THES

T1 - The Proteasome-associated deubiquitinase UCHL5/UBH-4 in proteasome modulation and as a prognostic marker in gastrointestinal cancers

AU - Arpalahti, Leena

N1 - M1 - 120 s.

PY - 2018

Y1 - 2018

N2 - The ubiquitin-proteasome system (UPS) is the major cellular pathway for controlled protein degradation, and, together with the autophagy-lysosome pathway, it is a central player in maintaining protein homeostasis. The catalytic core of the UPS is the proteasome, a complex holoenzyme composed of multiple different subunits with varying functions. Disruptions in the UPS are associated with many pathological conditions, including aging-related neurological diseases (such as Alzheimer's, Parkinson's, or Huntington's disease), as well as different cancers. Proteasome inhibitors (e.g. Bortezomib) are in use as cancer therapeutics (e.g. in refractory multiple myeloma and mantle cell lymphoma), but dose-limiting toxicities, drug-resistance and other adverse side-effects have created an acute need for identifying alternative targets that modulate the UPS. Yet, despite its wide-ranging importance, it remains to be defined how UPS is regulated, especially in vivo. The purpose of this thesis was to provide new information on UPS modulation in a living, multicellular organism, with the help of the model organism Caenorhabditis elegans. Further, the aim was to investigate the potential role of an identified proteasome regulator UCHL5/UBH-4 as a biomarker in three gastrointestinal cancers: colorectal cancer (CRC), gastric cancer (GC) and pancreatic ductal adenocarcinoma (PDAC). In the first part of the study, it was established that UCHL5/UBH-4, a proteasome-associated deubiquitinating enzyme (DUB), modulates proteasome activity in C. elegans, and additionally increases the degradation of proteotoxic proteins in human cancer cells. In C. elegans, UBH-4 expression was demonstrated to be regulated by the ageing-regulating Insulin/IGF-1 signaling (IIS) pathway through the transcription factor DAF-16 in a tissue-specific manner. Further, minor knockdown of ubh-4 resulted in a short lifespan extension without affecting progeny amounts. In the second part of the study, the role of UCHL5 was investigated in various gastrointestinal cancers. UCHL5 tumorexpression was scored with immunohistochemistry from representative patient tumor samples in CRC, GC and PDAC. UCHL5-immunoexpression correlated with increased survival in the subgroup of patients with lymph node-positive (Dukes C/stage III) rectal cancer. In addition, both positive nuclear and high cytoplasmic UCHL5-immunoexpression associated with better prognosis in PDAC. Positive UCHL5-immunoexpression was also linked to enhanced survival in the subgroups of gastric cancer patients with small tumors (

AB - The ubiquitin-proteasome system (UPS) is the major cellular pathway for controlled protein degradation, and, together with the autophagy-lysosome pathway, it is a central player in maintaining protein homeostasis. The catalytic core of the UPS is the proteasome, a complex holoenzyme composed of multiple different subunits with varying functions. Disruptions in the UPS are associated with many pathological conditions, including aging-related neurological diseases (such as Alzheimer's, Parkinson's, or Huntington's disease), as well as different cancers. Proteasome inhibitors (e.g. Bortezomib) are in use as cancer therapeutics (e.g. in refractory multiple myeloma and mantle cell lymphoma), but dose-limiting toxicities, drug-resistance and other adverse side-effects have created an acute need for identifying alternative targets that modulate the UPS. Yet, despite its wide-ranging importance, it remains to be defined how UPS is regulated, especially in vivo. The purpose of this thesis was to provide new information on UPS modulation in a living, multicellular organism, with the help of the model organism Caenorhabditis elegans. Further, the aim was to investigate the potential role of an identified proteasome regulator UCHL5/UBH-4 as a biomarker in three gastrointestinal cancers: colorectal cancer (CRC), gastric cancer (GC) and pancreatic ductal adenocarcinoma (PDAC). In the first part of the study, it was established that UCHL5/UBH-4, a proteasome-associated deubiquitinating enzyme (DUB), modulates proteasome activity in C. elegans, and additionally increases the degradation of proteotoxic proteins in human cancer cells. In C. elegans, UBH-4 expression was demonstrated to be regulated by the ageing-regulating Insulin/IGF-1 signaling (IIS) pathway through the transcription factor DAF-16 in a tissue-specific manner. Further, minor knockdown of ubh-4 resulted in a short lifespan extension without affecting progeny amounts. In the second part of the study, the role of UCHL5 was investigated in various gastrointestinal cancers. UCHL5 tumorexpression was scored with immunohistochemistry from representative patient tumor samples in CRC, GC and PDAC. UCHL5-immunoexpression correlated with increased survival in the subgroup of patients with lymph node-positive (Dukes C/stage III) rectal cancer. In addition, both positive nuclear and high cytoplasmic UCHL5-immunoexpression associated with better prognosis in PDAC. Positive UCHL5-immunoexpression was also linked to enhanced survival in the subgroups of gastric cancer patients with small tumors (

KW - Adenocarcinoma

KW - Biomarkers, Tumor

KW - Caenorhabditis elegans

KW - Carcinoma, Pancreatic Ductal

KW - Colorectal Neoplasms

KW - Deubiquitinating Enzymes

KW - Disease-Free Survival

KW - Gene Expression Regulation, Neoplastic

KW - Insulin

KW - Insulin-Like Growth Factor I

KW - Lymphatic Metastasis

KW - Neoplasm Staging

KW - Prognosis

KW - Proteasome Endopeptidase Complex

KW - +metabolism

KW - Signal Transduction

KW - Stomach Neoplasms

KW - Transcription Factors

KW - +genetics

KW - Ubiquitin Thiolesterase

KW - +biosynthesis

KW - 3111 Biomedicine

KW - 3122 Cancers

M3 - Doctoral Thesis

SN - 978-951-51-4016-6

T3 - Dissertationes Scholae Doctoralis Ad Sanitatem Investigandam Universitatis Helsinkiensis

PB - Helsingin yliopisto

CY - Helsinki

ER -

Arpalahti L. The Proteasome-associated deubiquitinase UCHL5/UBH-4 in proteasome modulation and as a prognostic marker in gastrointestinal cancers. Helsinki: Helsingin yliopisto, 2018. 120 p. (Dissertationes Scholae Doctoralis Ad Sanitatem Investigandam Universitatis Helsinkiensis; 11/2018).