The LEF1/CYLD axis and cIAPs regulate RIP1 deubiquitination and trigger apoptosis in selenite-treated colorectal cancer cells

P Wu; K J Shi; J J An; Y L Ci; F Li; K Y Hui; Y Yang; C M Xu

doi:10.1038/cddis.2014.13

The LEF1/CYLD axis and cIAPs regulate RIP1 deubiquitination and trigger apoptosis in selenite-treated colorectal cancer cells

Cell Death Dis. 2014 Feb 27;5(2):e1085. doi: 10.1038/cddis.2014.13.

Authors

P Wu¹, K J Shi¹, J J An¹, Y L Ci¹, F Li¹, K Y Hui¹, Y Yang¹, C M Xu¹

Affiliation

¹ State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medicine Sciences and School of Basic Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.

Abstract

Inhibitor-of-apoptosis protein (IAP) inhibitors have been reported to synergistically reduce cell viability in combination with a variety of chemotherapeutic drugs via targeted cellular IAP (cIAP) depletion. Here, we found that cIAP silencing sensitised colorectal cancer (CRC) cells to selenite-induced apoptosis. Upon selenite treatment, the K63-linked ubiquitin chains on receptor-interacting protein 1 (RIP1) were removed, leading to the formation of the death-inducing complex and subsequent caspase-8 activation. Although the ubiquitinases cIAP1 and cIAP2 were significantly downregulated after a 24-h selenite treatment, cylindromatosis (CYLD) deubiquitinase protein levels were marginally upregulated. Chromatin immunoprecipitation assays revealed that lymphoid enhancer factor-1 (LEF1) dissociated from the CYLD promoter upon selenite treatment, thus abolishing suppression of CYLD gene expression. We corroborated these findings in a CRC xenograft animal model using immunohistochemistry. Collectively, our findings demonstrate that selenite caused CYLD upregulation via LEF1 and cIAP downregulation, both of which contribute to the degradation of ubiquitin chains on RIP1 and subsequent caspase-8 activation and apoptosis. Importantly, our results identify a LEF1-binding site in the CYLD promoter as a potential target for combinational therapy as an alternative to cIAPs.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antineoplastic Agents / pharmacology*
Apoptosis / drug effects*
Baculoviral IAP Repeat-Containing 3 Protein
Binding Sites
Caspase 8 / genetics
Caspase 8 / metabolism
Colorectal Neoplasms / drug therapy*
Colorectal Neoplasms / genetics
Colorectal Neoplasms / metabolism
Colorectal Neoplasms / pathology
Deubiquitinating Enzyme CYLD
Enzyme Activation
Gene Expression Regulation, Neoplastic
HCT116 Cells
Humans
Inhibitor of Apoptosis Proteins / genetics
Inhibitor of Apoptosis Proteins / metabolism*
Lymphoid Enhancer-Binding Factor 1 / genetics
Lymphoid Enhancer-Binding Factor 1 / metabolism*
Mice
Mice, Nude
Nuclear Pore Complex Proteins / metabolism*
Promoter Regions, Genetic
RNA Interference
RNA-Binding Proteins / metabolism*
Selenious Acid / pharmacology*
Signal Transduction
Time Factors
Transfection
Tumor Burden / drug effects
Tumor Suppressor Proteins / genetics
Tumor Suppressor Proteins / metabolism*
Ubiquitin-Protein Ligases
Ubiquitination
Xenograft Model Antitumor Assays

Substances

AGFG1 protein, human
Antineoplastic Agents
Inhibitor of Apoptosis Proteins
LEF1 protein, human
Lymphoid Enhancer-Binding Factor 1
Nuclear Pore Complex Proteins
RNA-Binding Proteins
Tumor Suppressor Proteins
BIRC2 protein, human
BIRC3 protein, human
Baculoviral IAP Repeat-Containing 3 Protein
Ubiquitin-Protein Ligases
CYLD protein, human
Deubiquitinating Enzyme CYLD
CASP8 protein, human
Caspase 8
Selenious Acid