DEREGULATION OF A-TO-I RNA EDITING IS FUNCTIONALLY AND CLINICALLY RELEVANT IN MULTIPLE MYELOMA
(Abstract release date: 05/19/16)
EHA Library. Teoh P. 06/09/16; 132784; E1235
Dr. Phaik Ju Teoh
Contributions
Contributions
Abstract
Abstract: E1235
Type: Eposter Presentation
Background
Multiple myeloma (MM) is a plasma cell neoplasm that remains high risk and incurable despite its therapeutic advancement. Adenosine-to-Inosine (A-to-I) RNA editing is a highly conserved post-transcriptional mechanism involving sequence alterations at the RNA but not the DNA level, mediated by ADAR family proteins (ADAR1, ADAR2 and ADAR3). RNA editing can result in recoding of the proteome, modification of mRNA stability and alteration in the miRNA biogenesis. In line with its physiological importance, an aberrant RNA editing activity has been implicated in various human cancers. However, the relationship between dysregulated RNA editing and the pathogenesis of MM remains elusive. Importantly, chromosome 1q21 which harbours the ADAR1 locus is amplified in more than 35% of MM, and this chromosomal abnormality is a poor prognostic marker. Considering the co-occupancy of other genes in 1q21, it is unknown if ADAR1 is an important driver gene.
Aims
We aim to define the RNA editome landscape of MM and to characterize the critical function of a disrupted editome in driving myelomagenesis. We would also like to delineate if ADAR1 is a critical gene in 1q21.
Methods
To establish the clinical significance of ADARs in MM, we analysed the publicly available myeloma datasets. Primary patient samples and human myeloma cell lines (HMCLs) were used as our study models. The level of ADARs was modulated through the highly-efficient lentivirus system. Systematic high-throughput RNA-sequencing is employed to investigate the genome-wide RNA editing status before and after ADAR1 knockdown and overexpression. The functional effects of differential ADARs expression were examined through cell viability (CTG), cell cycle (PI staining) and colony formation (Methocult semi-solid medium) assays.
Results
Comparing with normal plasma cells, MM samples showed a severely disrupted ADAR1:ADAR2 expression ratio, in which an overexpression of ADAR1 and downregulation of ADAR2 were observed. In correlation, we identified that there was a close association between 1q21 amplification and ADAR1 expression level, which consistently increases along the disease progression route, i.e. from normal plasma to MGUS, SMM and finally MM. Furthermore, analysis based on the disease subtypes revealed that the 4p16 and MAF subtypes (high-risk prognostic groups) displayed significantly higher ADAR1 expression than other groups, signifying its role in conferring an aggressive disease nature. More importantly, patients with high ADAR1 and low ADAR2 expression demonstrated a poorer overall survival. At the physiological level, knocking down and overexpressing ADAR1 in HMCLs affects the global editing events, as detected by RNA-sequencing. Gene specific validation demonstrated a differential degree of A-to-I conversion of bona fide ADAR targets, depending on the ADAR1 expression level. In vitro analysis implicated that both ADAR1 and ADAR2 can functionally affect MM growth and survival, whereby, ADAR1 behaves like an oncogene and ADAR2 displayed tumor suppressor properties. When the stable cell lines were treated with velcade, ADAR1-knockdown cells showed increased sensitivity while ADAR2-silenced cells were more resistant to the drug.
Conclusion
Considering that RNA editing is a widespread occurence in the human genome (85%), its biological significance in MM cannot be undermined. Our study unveils a potential novel role of ADAR-mediated-A-to-I-editing in conferring myelomagenesis. The functional relevance of ADAR1 and ADAR2 denotes that the RNA editing activity is clinically important and may represent an important therapeutic target for MM. Further characterization of the direct mechanisms of A-to-I editing will provide critical knowledge on whether this event would provide an extra layer of epigenetic deregulation to MM, leading to a worse disease prognosis.
Session topic: E-poster
Keyword(s): Bortezomib, Chromosomal abnormality, Epigenetic, Myeloma
Type: Eposter Presentation
Background
Multiple myeloma (MM) is a plasma cell neoplasm that remains high risk and incurable despite its therapeutic advancement. Adenosine-to-Inosine (A-to-I) RNA editing is a highly conserved post-transcriptional mechanism involving sequence alterations at the RNA but not the DNA level, mediated by ADAR family proteins (ADAR1, ADAR2 and ADAR3). RNA editing can result in recoding of the proteome, modification of mRNA stability and alteration in the miRNA biogenesis. In line with its physiological importance, an aberrant RNA editing activity has been implicated in various human cancers. However, the relationship between dysregulated RNA editing and the pathogenesis of MM remains elusive. Importantly, chromosome 1q21 which harbours the ADAR1 locus is amplified in more than 35% of MM, and this chromosomal abnormality is a poor prognostic marker. Considering the co-occupancy of other genes in 1q21, it is unknown if ADAR1 is an important driver gene.
Aims
We aim to define the RNA editome landscape of MM and to characterize the critical function of a disrupted editome in driving myelomagenesis. We would also like to delineate if ADAR1 is a critical gene in 1q21.
Methods
To establish the clinical significance of ADARs in MM, we analysed the publicly available myeloma datasets. Primary patient samples and human myeloma cell lines (HMCLs) were used as our study models. The level of ADARs was modulated through the highly-efficient lentivirus system. Systematic high-throughput RNA-sequencing is employed to investigate the genome-wide RNA editing status before and after ADAR1 knockdown and overexpression. The functional effects of differential ADARs expression were examined through cell viability (CTG), cell cycle (PI staining) and colony formation (Methocult semi-solid medium) assays.
Results
Comparing with normal plasma cells, MM samples showed a severely disrupted ADAR1:ADAR2 expression ratio, in which an overexpression of ADAR1 and downregulation of ADAR2 were observed. In correlation, we identified that there was a close association between 1q21 amplification and ADAR1 expression level, which consistently increases along the disease progression route, i.e. from normal plasma to MGUS, SMM and finally MM. Furthermore, analysis based on the disease subtypes revealed that the 4p16 and MAF subtypes (high-risk prognostic groups) displayed significantly higher ADAR1 expression than other groups, signifying its role in conferring an aggressive disease nature. More importantly, patients with high ADAR1 and low ADAR2 expression demonstrated a poorer overall survival. At the physiological level, knocking down and overexpressing ADAR1 in HMCLs affects the global editing events, as detected by RNA-sequencing. Gene specific validation demonstrated a differential degree of A-to-I conversion of bona fide ADAR targets, depending on the ADAR1 expression level. In vitro analysis implicated that both ADAR1 and ADAR2 can functionally affect MM growth and survival, whereby, ADAR1 behaves like an oncogene and ADAR2 displayed tumor suppressor properties. When the stable cell lines were treated with velcade, ADAR1-knockdown cells showed increased sensitivity while ADAR2-silenced cells were more resistant to the drug.
Conclusion
Considering that RNA editing is a widespread occurence in the human genome (85%), its biological significance in MM cannot be undermined. Our study unveils a potential novel role of ADAR-mediated-A-to-I-editing in conferring myelomagenesis. The functional relevance of ADAR1 and ADAR2 denotes that the RNA editing activity is clinically important and may represent an important therapeutic target for MM. Further characterization of the direct mechanisms of A-to-I editing will provide critical knowledge on whether this event would provide an extra layer of epigenetic deregulation to MM, leading to a worse disease prognosis.
Session topic: E-poster
Keyword(s): Bortezomib, Chromosomal abnormality, Epigenetic, Myeloma
Abstract: E1235
Type: Eposter Presentation
Background
Multiple myeloma (MM) is a plasma cell neoplasm that remains high risk and incurable despite its therapeutic advancement. Adenosine-to-Inosine (A-to-I) RNA editing is a highly conserved post-transcriptional mechanism involving sequence alterations at the RNA but not the DNA level, mediated by ADAR family proteins (ADAR1, ADAR2 and ADAR3). RNA editing can result in recoding of the proteome, modification of mRNA stability and alteration in the miRNA biogenesis. In line with its physiological importance, an aberrant RNA editing activity has been implicated in various human cancers. However, the relationship between dysregulated RNA editing and the pathogenesis of MM remains elusive. Importantly, chromosome 1q21 which harbours the ADAR1 locus is amplified in more than 35% of MM, and this chromosomal abnormality is a poor prognostic marker. Considering the co-occupancy of other genes in 1q21, it is unknown if ADAR1 is an important driver gene.
Aims
We aim to define the RNA editome landscape of MM and to characterize the critical function of a disrupted editome in driving myelomagenesis. We would also like to delineate if ADAR1 is a critical gene in 1q21.
Methods
To establish the clinical significance of ADARs in MM, we analysed the publicly available myeloma datasets. Primary patient samples and human myeloma cell lines (HMCLs) were used as our study models. The level of ADARs was modulated through the highly-efficient lentivirus system. Systematic high-throughput RNA-sequencing is employed to investigate the genome-wide RNA editing status before and after ADAR1 knockdown and overexpression. The functional effects of differential ADARs expression were examined through cell viability (CTG), cell cycle (PI staining) and colony formation (Methocult semi-solid medium) assays.
Results
Comparing with normal plasma cells, MM samples showed a severely disrupted ADAR1:ADAR2 expression ratio, in which an overexpression of ADAR1 and downregulation of ADAR2 were observed. In correlation, we identified that there was a close association between 1q21 amplification and ADAR1 expression level, which consistently increases along the disease progression route, i.e. from normal plasma to MGUS, SMM and finally MM. Furthermore, analysis based on the disease subtypes revealed that the 4p16 and MAF subtypes (high-risk prognostic groups) displayed significantly higher ADAR1 expression than other groups, signifying its role in conferring an aggressive disease nature. More importantly, patients with high ADAR1 and low ADAR2 expression demonstrated a poorer overall survival. At the physiological level, knocking down and overexpressing ADAR1 in HMCLs affects the global editing events, as detected by RNA-sequencing. Gene specific validation demonstrated a differential degree of A-to-I conversion of bona fide ADAR targets, depending on the ADAR1 expression level. In vitro analysis implicated that both ADAR1 and ADAR2 can functionally affect MM growth and survival, whereby, ADAR1 behaves like an oncogene and ADAR2 displayed tumor suppressor properties. When the stable cell lines were treated with velcade, ADAR1-knockdown cells showed increased sensitivity while ADAR2-silenced cells were more resistant to the drug.
Conclusion
Considering that RNA editing is a widespread occurence in the human genome (85%), its biological significance in MM cannot be undermined. Our study unveils a potential novel role of ADAR-mediated-A-to-I-editing in conferring myelomagenesis. The functional relevance of ADAR1 and ADAR2 denotes that the RNA editing activity is clinically important and may represent an important therapeutic target for MM. Further characterization of the direct mechanisms of A-to-I editing will provide critical knowledge on whether this event would provide an extra layer of epigenetic deregulation to MM, leading to a worse disease prognosis.
Session topic: E-poster
Keyword(s): Bortezomib, Chromosomal abnormality, Epigenetic, Myeloma
Type: Eposter Presentation
Background
Multiple myeloma (MM) is a plasma cell neoplasm that remains high risk and incurable despite its therapeutic advancement. Adenosine-to-Inosine (A-to-I) RNA editing is a highly conserved post-transcriptional mechanism involving sequence alterations at the RNA but not the DNA level, mediated by ADAR family proteins (ADAR1, ADAR2 and ADAR3). RNA editing can result in recoding of the proteome, modification of mRNA stability and alteration in the miRNA biogenesis. In line with its physiological importance, an aberrant RNA editing activity has been implicated in various human cancers. However, the relationship between dysregulated RNA editing and the pathogenesis of MM remains elusive. Importantly, chromosome 1q21 which harbours the ADAR1 locus is amplified in more than 35% of MM, and this chromosomal abnormality is a poor prognostic marker. Considering the co-occupancy of other genes in 1q21, it is unknown if ADAR1 is an important driver gene.
Aims
We aim to define the RNA editome landscape of MM and to characterize the critical function of a disrupted editome in driving myelomagenesis. We would also like to delineate if ADAR1 is a critical gene in 1q21.
Methods
To establish the clinical significance of ADARs in MM, we analysed the publicly available myeloma datasets. Primary patient samples and human myeloma cell lines (HMCLs) were used as our study models. The level of ADARs was modulated through the highly-efficient lentivirus system. Systematic high-throughput RNA-sequencing is employed to investigate the genome-wide RNA editing status before and after ADAR1 knockdown and overexpression. The functional effects of differential ADARs expression were examined through cell viability (CTG), cell cycle (PI staining) and colony formation (Methocult semi-solid medium) assays.
Results
Comparing with normal plasma cells, MM samples showed a severely disrupted ADAR1:ADAR2 expression ratio, in which an overexpression of ADAR1 and downregulation of ADAR2 were observed. In correlation, we identified that there was a close association between 1q21 amplification and ADAR1 expression level, which consistently increases along the disease progression route, i.e. from normal plasma to MGUS, SMM and finally MM. Furthermore, analysis based on the disease subtypes revealed that the 4p16 and MAF subtypes (high-risk prognostic groups) displayed significantly higher ADAR1 expression than other groups, signifying its role in conferring an aggressive disease nature. More importantly, patients with high ADAR1 and low ADAR2 expression demonstrated a poorer overall survival. At the physiological level, knocking down and overexpressing ADAR1 in HMCLs affects the global editing events, as detected by RNA-sequencing. Gene specific validation demonstrated a differential degree of A-to-I conversion of bona fide ADAR targets, depending on the ADAR1 expression level. In vitro analysis implicated that both ADAR1 and ADAR2 can functionally affect MM growth and survival, whereby, ADAR1 behaves like an oncogene and ADAR2 displayed tumor suppressor properties. When the stable cell lines were treated with velcade, ADAR1-knockdown cells showed increased sensitivity while ADAR2-silenced cells were more resistant to the drug.
Conclusion
Considering that RNA editing is a widespread occurence in the human genome (85%), its biological significance in MM cannot be undermined. Our study unveils a potential novel role of ADAR-mediated-A-to-I-editing in conferring myelomagenesis. The functional relevance of ADAR1 and ADAR2 denotes that the RNA editing activity is clinically important and may represent an important therapeutic target for MM. Further characterization of the direct mechanisms of A-to-I editing will provide critical knowledge on whether this event would provide an extra layer of epigenetic deregulation to MM, leading to a worse disease prognosis.
Session topic: E-poster
Keyword(s): Bortezomib, Chromosomal abnormality, Epigenetic, Myeloma
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