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THE T-CELL LEUKEMIA ASSOCIATED RIBOSOMAL RPL10 R98S MUTATION ENHANCES JAK-STAT SIGNALING
Author(s):
Tiziana Girardi
,
Tiziana Girardi
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Sergey O. Sulima
,
Sergey O. Sulima
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Stijn Vereecke
,
Stijn Vereecke
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Yousuf Khan
,
Yousuf Khan
Affiliations:
Department of Cell Biology and Molecular Genetics,University of Maryland,College Park,United States
Laura Fancello
,
Laura Fancello
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Zachary Flickinger
,
Zachary Flickinger
Affiliations:
Department of Cell Biology and Molecular Genetics,University of Maryland,College Park,United States
Claire Schwab
,
Claire Schwab
Affiliations:
Leukaemia Research Cytogenetics Group,Northern Institute for Cancer Research, Newcastle University,Newcastle-upon-Tyne,United Kingdom
Joyce Op de Beeck
,
Joyce Op de Beeck
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Jelle Verbeeck
,
Jelle Verbeeck
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Jonathan Royaert
,
Jonathan Royaert
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Ellen Geerdens
,
Ellen Geerdens
Affiliations:
Center for Human Genetics, LKI,KU Leuven,Leuven,Belgium;Center for Cancer Biology,VIB,Leuven,Belgium
Carmen Vicente
,
Carmen Vicente
Affiliations:
Center for Cancer Biology,VIB,Leuven,Belgium;Center for Human Genetics, LKI,KU Leuven,Leuven,Belgium
Simon Bornschein
,
Simon Bornschein
Affiliations:
Center for Cancer Biology,VIB,Leuven,Belgium;Center for Human Genetics, LKI,KU Leuven,Leuven,Belgium
Christine J. Harrison
,
Christine J. Harrison
Affiliations:
Leukaemia Research Cytogenetics Group,Northern Institute for Cancer Research, Newcastle University,Newcastle-upon-Tyne,United Kingdom
Jules P. Meijerink
,
Jules P. Meijerink
Affiliations:
Department of Pediatric Oncology/Hematology,Erasmus Medical Center,Rotterdam,Netherlands
Jan Cools
,
Jan Cools
Affiliations:
Center for Cancer Biology,VIB,Leuven,Belgium;Center for Human Genetics, LKI,KU Leuven,Leuven,Belgium
Jonathan D. Dinman
,
Jonathan D. Dinman
Affiliations:
Department of Cell Biology and Molecular Genetics,University of Maryland,College Park,United States
Kim R Kampen
,
Kim R Kampen
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
Kim De Keersmaecker
Kim De Keersmaecker
Affiliations:
Department of Oncology, LKI,KU Leuven,Leuven,Belgium
(Abstract release date: 05/18/17) EHA Library. Vereecke S. 06/24/17; 181726; S439
S Vereecke
S Vereecke
Contributions
PDF Abstract
Abstract

Abstract: S439

Type: Oral Presentation

Presentation during EHA22: On Saturday, June 24, 2017 from 12:15 - 12:30

Location: Room N105

Background

Several somatic ribosome defects have recently been discovered in cancer, yet their underlying oncogenic mechanisms remain poorly understood. Alterations in ribosomal protein genes RPL5, RPL10, and RPL22 have been described in ~20% of T-cell acute lymphoblastic leukemia (T-ALL) cases. Whereas RPL5 and RPL22 show heterozygous inactivating mutations and deletions, RPL10 contains a clear mutational hotspot at residue arginine 98 (R98), with 8% of pediatric T-ALL patients harboring this RPL10 R98S missense mutation.

Aims
Investigating the pathogenic role of the recurrent R98S mutation in ribosomal protein L10 (RPL10) in T-ALL.

Methods

A label-free quantitative proteomics experiment was performed to screen for differentially expressed proteins in engineered mouse lymphoid Ba/F3 cells expressing RPL10 WT or RPL10 R98S. Differences in protein expression were further validated in hematopoietic cells derived from a transgenic RPL10 R98S knock-in mouse model and in material derived from xenografted T-ALL patient samples.

Results
The differential proteome screen revealed overexpression of several Jak-Stat signaling components (Csf2rb/2, Jak1, Stat1, Stat3, Stat5a/b and Stat6) in engineered RPL10 R98S mouse lymphoid cells, which we confirmed in hematopoietic cells derived from a transgenic RPL10 R98S mouse model. The relevance of this overexpression was illustrated by enhanced Jak-Stat pathway activation upon cytokine stimulation in RPL10 R98S lymphoid cells, as well as increased sensitivity of these cells to clinically used JAK-STAT inhibitors ruxolitinib and pimozide. RPL10 R98S positive leukemia patients likewise showed overexpression of IL7RA, JAK1 and STAT5, increased sensitivity to pimozide, as well as a mutually exclusive mutation pattern between RPL10 R98S and JAK-STAT lesions, suggesting that RPL10-R98S also modulates the cascade in human T-ALL. Programmed -1 ribosomal frameshifting (-1 PRF) recently emerged as a post-transcriptional mechanism regulating expression of cytokine receptors. We identified -1 PRF signals in mouse and human Jak-Stat genes and observed RPL10 R98S associated frameshifting reduction in several of these, which may contribute to their overexpression. Altered levels of -1 PRF can however only partially explain observed JAK-STAT protein expression changes, and transcriptional changes and altered protein stability are also involved. Indeed, our data point to altered proteasome activity and composition in RPL10 R98S cells, with upregulation of immunoproteasome specific catalytic subunits, which may explain the increased stability of particular proteins such as Jak1. Of further medical interest, RPL10 R98S cells showed reduced proteasome activity and enhanced sensitivity to the clinically used proteasome inhibitors bortezomib and carfilzomib.

Conclusion

We explored the molecular mechanism by which the RPL10 R98S mutation contributes to the pathogenesis of T-ALL. We propose a model in which R98S associated decreases in -1 PRF levels, combined with changes in the degradation of particular proteins and potential other mechanisms such as transcriptional regulation, leads to selective upregulation of the oncogenic JAK-STAT cascade (Figure 1). Besides expanding the relevance of the JAK-STAT cascade in T-ALL and leukemia in general, our results have therapeutic potential since cells harboring the RPL10 R98S mutation are sensitized towards clinically used JAK-STAT and proteasome inhibitors.

Session topic: 1. Acute lymphoblastic leukemia - Biology

Abstract: S439

Type: Oral Presentation

Presentation during EHA22: On Saturday, June 24, 2017 from 12:15 - 12:30

Location: Room N105

Background

Several somatic ribosome defects have recently been discovered in cancer, yet their underlying oncogenic mechanisms remain poorly understood. Alterations in ribosomal protein genes RPL5, RPL10, and RPL22 have been described in ~20% of T-cell acute lymphoblastic leukemia (T-ALL) cases. Whereas RPL5 and RPL22 show heterozygous inactivating mutations and deletions, RPL10 contains a clear mutational hotspot at residue arginine 98 (R98), with 8% of pediatric T-ALL patients harboring this RPL10 R98S missense mutation.

Aims
Investigating the pathogenic role of the recurrent R98S mutation in ribosomal protein L10 (RPL10) in T-ALL.

Methods

A label-free quantitative proteomics experiment was performed to screen for differentially expressed proteins in engineered mouse lymphoid Ba/F3 cells expressing RPL10 WT or RPL10 R98S. Differences in protein expression were further validated in hematopoietic cells derived from a transgenic RPL10 R98S knock-in mouse model and in material derived from xenografted T-ALL patient samples.

Results
The differential proteome screen revealed overexpression of several Jak-Stat signaling components (Csf2rb/2, Jak1, Stat1, Stat3, Stat5a/b and Stat6) in engineered RPL10 R98S mouse lymphoid cells, which we confirmed in hematopoietic cells derived from a transgenic RPL10 R98S mouse model. The relevance of this overexpression was illustrated by enhanced Jak-Stat pathway activation upon cytokine stimulation in RPL10 R98S lymphoid cells, as well as increased sensitivity of these cells to clinically used JAK-STAT inhibitors ruxolitinib and pimozide. RPL10 R98S positive leukemia patients likewise showed overexpression of IL7RA, JAK1 and STAT5, increased sensitivity to pimozide, as well as a mutually exclusive mutation pattern between RPL10 R98S and JAK-STAT lesions, suggesting that RPL10-R98S also modulates the cascade in human T-ALL. Programmed -1 ribosomal frameshifting (-1 PRF) recently emerged as a post-transcriptional mechanism regulating expression of cytokine receptors. We identified -1 PRF signals in mouse and human Jak-Stat genes and observed RPL10 R98S associated frameshifting reduction in several of these, which may contribute to their overexpression. Altered levels of -1 PRF can however only partially explain observed JAK-STAT protein expression changes, and transcriptional changes and altered protein stability are also involved. Indeed, our data point to altered proteasome activity and composition in RPL10 R98S cells, with upregulation of immunoproteasome specific catalytic subunits, which may explain the increased stability of particular proteins such as Jak1. Of further medical interest, RPL10 R98S cells showed reduced proteasome activity and enhanced sensitivity to the clinically used proteasome inhibitors bortezomib and carfilzomib.

Conclusion

We explored the molecular mechanism by which the RPL10 R98S mutation contributes to the pathogenesis of T-ALL. We propose a model in which R98S associated decreases in -1 PRF levels, combined with changes in the degradation of particular proteins and potential other mechanisms such as transcriptional regulation, leads to selective upregulation of the oncogenic JAK-STAT cascade (Figure 1). Besides expanding the relevance of the JAK-STAT cascade in T-ALL and leukemia in general, our results have therapeutic potential since cells harboring the RPL10 R98S mutation are sensitized towards clinically used JAK-STAT and proteasome inhibitors.

Session topic: 1. Acute lymphoblastic leukemia - Biology

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