Single cell analyses reveals a non-canonical EZH2 activity as main driver of RA resistance in PLZF/RARA leukemia [scRNA-seq]
Ontology highlight
ABSTRACT: Resistance to treatment is due to the heterogeneity of the tumor which contains a subset of cancer cells that escape treatment and are responsible for the relapse. We took advantage of the PLZF/RARA retinoic acid (RA) resistant acute promyelocytic leukemia (APL) model to catch relapse-initiating cell features and their vulnerabilities. By developing an integrative single-cell multi-omics analysis (scRNA-seq and scATAC-seq), we uncovered transcriptional and chromatin heterogeneity of the PLZF/RARA APL blasts. We highlighted a subset of cells insensitive to RA-induced differentiation with a strong DNA repair signature ("Rep" cluster) and exhibiting a fine tuned transcriptional network targeting the histone methyltransferase Ezh2. Combining epigenomic profiling with mouse-derived models for Ezh2 catalytic inhibition or total KO, we revealed an independent methyltransferase Ezh2 activity linked to RA resistance. These findings demonstrate the power of single-cell multi-omics integration to highlight paths to sensitize therapy-resistant leukemia cells
Project description:Resistance to treatment is due to the heterogeneity of the tumor which contains a subset of cancer cells that escape treatment and are responsible for the relapse. We took advantage of the PLZF/RARA retinoic acid (RA) resistant acute promyelocytic leukemia (APL) model to catch relapse-initiating cell features and their vulnerabilities. By developing an integrative single-cell multi-omics analysis (scRNA-seq and scATAC-seq), we uncovered transcriptional and chromatin heterogeneity of the PLZF/RARA APL blasts. We highlighted a subset of cells insensitive to RA-induced differentiation with a strong DNA repair signature ("Rep" cluster) and exhibiting a fine tuned transcriptional network targeting the histone methyltransferase Ezh2. Combining epigenomic profiling with mouse-derived models for Ezh2 catalytic inhibition or total KO, we revealed an independent methyltransferase Ezh2 activity linked to RA resistance. These findings demonstrate the power of single-cell multi-omics integration to highlight paths to sensitize therapy-resistant leukemia cells
Project description:Resistance to treatment is due to the heterogeneity of the tumor which contains a subset of cancer cells that escape treatment and are responsible for the relapse. We took advantage of the PLZF/RARA retinoic acid (RA) resistant acute promyelocytic leukemia (APL) model to catch relapse-initiating cell features and their vulnerabilities. By developing an integrative single-cell multi-omics analysis (scRNA-seq and scATAC-seq), we uncovered transcriptional and chromatin heterogeneity of the PLZF/RARA APL blasts. We highlighted a subset of cells insensitive to RA-induced differentiation with a strong DNA repair signature ("Rep" cluster) and exhibiting a fine tuned transcriptional network targeting the histone methyltransferase Ezh2. Combining epigenomic profiling with mouse-derived models for Ezh2 catalytic inhibition or total KO, we revealed an independent methyltransferase Ezh2 activity linked to RA resistance. These findings demonstrate the power of single-cell multi-omics integration to highlight paths to sensitize therapy-resistant leukemia cells
Project description:Resistance to treatment is due to the heterogeneity of the tumor which contains a subset of cancer cells that escape treatment and are responsible for the relapse. We took advantage of the PLZF/RARA retinoic acid (RA) resistant acute promyelocytic leukemia (APL) model to catch relapse-initiating cell features and their vulnerabilities. By developing an integrative single-cell multi-omics analysis (scRNA-seq and scATAC-seq), we uncovered transcriptional and chromatin heterogeneity of the PLZF/RARA APL blasts. We highlighted a subset of cells insensitive to RA-induced differentiation with a strong DNA repair signature ("Rep" cluster) and exhibiting a fine tuned transcriptional network targeting the histone methyltransferase Ezh2. Combining epigenomic profiling with mouse-derived models for Ezh2 catalytic inhibition or total KO, we revealed an independent methyltransferase Ezh2 activity linked to RA resistance. These findings demonstrate the power of single-cell multi-omics integration to highlight paths to sensitize therapy-resistant leukemia cells
Project description:Resistance to treatment is due to the heterogeneity of the tumor which contains a subset of cancer cells that escape treatment and are responsible for the relapse. We took advantage of the PLZF/RARA retinoic acid (RA) resistant acute promyelocytic leukemia (APL) model to catch relapse-initiating cell features and their vulnerabilities. By developing an integrative single-cell multi-omics analysis (scRNA-seq and scATAC-seq), we uncovered transcriptional and chromatin heterogeneity of the PLZF/RARA APL blasts. We highlighted a subset of cells insensitive to RA-induced differentiation with a strong DNA repair signature ("Rep" cluster) and exhibiting a fine tuned transcriptional network targeting the histone methyltransferase Ezh2. Combining epigenomic profiling with mouse-derived models for Ezh2 catalytic inhibition or total KO, we revealed an independent methyltransferase Ezh2 activity linked to RA resistance. These findings demonstrate the power of single-cell multi-omics integration to highlight paths to sensitize therapy-resistant leukemia cells
Project description:The therapy-induced PML/RARA catabolism elicits the loss of APL-initiating cell self-renewal through PML NB reformation and P53 activation. These results explain the curative activity of the RA/arsenic combination, the resistance to RA of PLZF/RARA-driven APLs and they raise the prospect that activation of this PML/P53 checkpoint might have therapeutic values in other malignancies. Gene expression profiles of 36 transgenic induced APL and 36 viral transduction APL were hybridized using Affymetrix Mouse Gene 1.0 ST Arrays
Project description:The therapy-induced PML/RARA catabolism elicits the loss of APL-initiating cell self-renewal through PML NB reformation and P53 activation. These results explain the curative activity of the RA/arsenic combination, the resistance to RA of PLZF/RARA-driven APLs and they raise the prospect that activation of this PML/P53 checkpoint might have therapeutic values in other malignancies.
Project description:Acute promyelocytic leukemia (APL) is a subtype of myeloid leukemia characterized by differentiation block at the promyelocyte stage. Besides the presence of chromosomal rearrangement t(15;17) leading to formation of PML-RARA fusion, other genetic alterations have also been implicated in APL. Here, we performed comprehensive mutational analysis of primary and relapse APL to identify somatic alterations which cooperate with PML-RARA in the pathogenesis of APL. We explored the mutational landscape using whole-exome (n=12) and subsequent targeted sequencing of 398 genes in 153 primary and 69 relapse APL. Both primary and relapse APL harbored an average of eight non-silent somatic mutations per exome. We observed recurrent alterations of FLT3, WT1, NRAS and KRAS in the newly diagnosed APL, while mutations in other genes commonly mutated in myeloid leukemia were rarely detected. The molecular signature of APL relapse was characterized by emergence of frequent mutations in PML and RARA genes. Our sequencing data also demonstrates incidence of loss-of-function mutations in previously unidentified genes, ARID1B and ARID1A, both of which encode for key components of the SWI/SNF complex. We show that knockdown of ARID1B in APL cell line, NB4, results in large scale activation of gene expression and reduced in vitro differentiation potential. Studying the effects of silensing ARID1B gene in NB4 cell lines
Project description:Acute promyelocytic leukemia (APL) is a subtype of myeloid leukemia characterized by differentiation block at the promyelocyte stage. Besides the presence of chromosomal rearrangement t(15;17) leading to formation of PML-RARA fusion, other genetic alterations have also been implicated in APL. Here, we performed comprehensive mutational analysis of primary and relapse APL to identify somatic alterations which cooperate with PML-RARA in the pathogenesis of APL. We explored the mutational landscape using whole-exome (n=12) and subsequent targeted sequencing of 398 genes in 153 primary and 69 relapse APL. Both primary and relapse APL harbored an average of eight non-silent somatic mutations per exome. We observed recurrent alterations of FLT3, WT1, NRAS and KRAS in the newly diagnosed APL, while mutations in other genes commonly mutated in myeloid leukemia were rarely detected. The molecular signature of APL relapse was characterized by emergence of frequent mutations in PML and RARA genes. Our sequencing data also demonstrates incidence of loss-of-function mutations in previously unidentified genes, ARID1B and ARID1A, both of which encode for key components of the SWI/SNF complex. We show that knockdown of ARID1B in APL cell line, NB4, results in large scale activation of gene expression and reduced in vitro differentiation potential.
Project description:The PML-RARA fusion protein is the hallmark driver of Acute Promyelocytic Leukemia (APL) and disrupts retinoic acid signaling, leading to wide-scale gene expression changes and uncontrolled proliferation of myeloid precursor cells. While known to be recruited to binding sites across the genome, its impact on gene regulation and expression is under-explored. Using integrated multi-omics datasets, we characterize the influence of PML-RARA binding on gene expression and regulation in an inducible cell line model and APL patient ex vivo samples. We find that genes whose regulatory elements recruit PML-RARA are not uniformly transcriptionally repressed, as commonly suggested, but also may be upregulated or remain unchanged. We develop a novel, computational machine learning application to deconvolute the complex, local transcription factor binding site environment at PML-RARA bound positions to reveal distinct signatures that modulate how PML-RARA directs the transcriptional response.
Project description:The PML-RARA fusion protein is the hallmark driver of Acute Promyelocytic Leukemia (APL) and disrupts retinoic acid signaling, leading to wide-scale gene expression changes and uncontrolled proliferation of myeloid precursor cells. While known to be recruited to binding sites across the genome, its impact on gene regulation and expression is under-explored. Using integrated multi-omics datasets, we characterize the influence of PML-RARA binding on gene expression and regulation in an inducible cell line model and APL patient ex vivo samples. We find that genes whose regulatory elements recruit PML-RARA are not uniformly transcriptionally repressed, as commonly suggested, but also may be upregulated or remain unchanged. We develop a novel, computational machine learning application to deconvolute the complex, local transcription factor binding site environment at PML-RARA bound positions to reveal distinct signatures that modulate how PML-RARA directs the transcriptional response.