Repeat to gene expression ratios in leukemic blast cells can stratify risk prediction in acute myeloid leukemia

Background Repeat elements constitute a large proportion of the human genome and recent evidence indicates that repeat element expression has functional roles in both physiological and pathological states. Specifically for cancer, transcription of endogenous retrotransposons is often suppressed to attenuate an anti-tumor immune response, whereas aberrant expression of heterochromatin-derived satellite RNA has been identified as a tumor driver. These insights demonstrate separate functions for the dysregulation of distinct repeat subclasses in either the attenuation or progression of human solid tumors. For hematopoietic malignancies, such as Acute Myeloid Leukemia (AML), only very few studies on the expression/dysregulation of repeat elements were done. Methods To study the expression of repeat elements in AML, we performed total-RNA sequencing of healthy CD34 + cells and of leukemic blast cells from primary AML patient material. We also developed an integrative bioinformatic approach that can quantify the expression of repeat transcripts from all repeat subclasses (SINE/ALU, LINE, ERV and satellites) in relation to the expression of gene and other non-repeat transcripts (i.e. R/G ratio). This novel approach can be used as an instructive signature for repeat element expression and has been extended to the analysis of poly(A)-RNA sequencing datasets from Blueprint and TCGA consortia that together comprise 120 AML patient samples. Results We identified that repeat element expression is generally down-regulated during hematopoietic differentiation and that relative changes in repeat to gene expression can stratify risk prediction of AML patients and correlate with overall survival probabilities. A high R/G ratio identifies AML patient subgroups with a favorable prognosis, whereas a low R/G ratio is prevalent in AML patient subgroups with a poor prognosis. Conclusions We developed an integrative bioinformatic approach that defines a general model for the analysis of repeat element dysregulation in physiological and pathological development. We find that changes in repeat to gene expression (i.e. R/G ratios) correlate with hematopoietic differentiation and can sub-stratify AML patients into low-risk and high-risk subgroups. Thus, the definition of a R/G ratio can serve as a valuable biomarker for AML and could also provide insights into differential patient response to epigenetic drug treatment.

Repeat to gene expression ratios in leukemic blast cells can stratify risk prediction in acute myeloid leukemia

BackgroundRepeat elements constitute a large proportion of the human genome and recent evidence indicates that repeat element expression has functional roles in both physiological and pathological states. Specifically for cancer, transcription of endogenous retrotransposons is often suppressed in order to attenuate an anti-tumor immune response, whereas aberrant expression of heterochromatin-derived satellite RNA has been identified as a tumor driver. These insights demonstrate separate functions for the dysregulation of distinct repeat subclasses in either the attenuation or progression of human solid tumors. For hematopoietic malignancies, such as Acute Myeloid Leukemia (AML), only very few studies on the expression/dysregulation of repeat elements were done. MethodsTo study the expression of repeat elements in AML, we performed total-RNA sequencing of healthy CD34+ cells and of leukemic blast cells from primary AML patient material. We also developed an integrative bioinformatic approach that can quantify the expression of repeat transcripts from all repeat subclasses (SINE/ALU, LINE and ERV elements and satellite repeats) in relation to the expression of gene and other non-repeat transcripts. This novel approach can be used as an instructive signature (R/G ratio) for repeat element expression and has been extended to the analysis of poly(A)-RNA sequencing datasets from Blueprint and TCGA consortia that together comprise 120 AML patient samples. ResultsWe identified that repeat element expression is generally down-regulated during hematopoietic differentiation and that relative changes in repeat to gene expression (i.e. R/G ratios) can stratify risk prediction of AML patients and correlate with overall survival probabilities. A high repeat to gene expression ratio identifies AML patient subgroups with a favorable prognosis, whereas a low repeat to gene expression is prevalent in AML patient subgroups with a poor prognosis. ConclusionsWe developed an integrative bioinformatic approach that defines a general model for the analysis of repeat element dysregulation in physiological and pathological development. We find that changes in repeat to gene expression (R/G ratios) correlate with hematopoietic differentiation and can sub-stratify AML patients into low-risk and high-risk subgroups. Thus, the definition of a R/G ratio can serve as a valuable biomarker for AML and could also provide insights into differential patient response to epigenetic drug treatment.

PGK1, a promising biomarker and therapeutic target for patients with acute myeloid leukemia who are susceptible to disease relapse

Background: Glycolysis, a multi-step enzymatic reaction, is considered to be the root of cancer development and progression. The aim of this study is to figure out the glycolytic enzyme, phosphoglycerate kinase 1 (PGK1) whether participate in the progression of acute myeloid leukemia (AML) and its possible mechanisms. Methods: Four datasets (GSE106096, GSE75086, GSE107968 and GSE106748) containing 30 leukemic blast cell samples of AML at diagnosis, 17 leukemic blast cell samples of AML relapse and 3 bone marrow CD34+ cell samples of healthy donors were downloaded from Gene Expression Omnibus (GEO) database and PGK1 was screened out as a potential survival biomarker in AML. Then we did a series of clinical sample verifications and gene set enrichment analysis (GSEA) focusing on PGK1. We further knocked down expression of PGK1 in myelogenous leukemia cell lines and explored its potential effects. Results: PGK1 expression was up-regulated among AML at diagnosis versus healthy control, AML relapse versus AML at diagnosis and AML relapse versus healthy control datasets. Through a serial of bioinformatic analyses (differentially expressed genes [DEGs] selection, function and pathway enrichments and protein-protein interaction [PPI] network establishment), PGK1 was identified as the most meaningful gene in AML progression. Furthermore, the generally high expression of PGK1 was confirmed in AML samples comparing with healthy controls in our single center and the high-expression PGK1 was associated with a comparatively low complete remission (CR) rate, a significantly high 5-year cumulative incidence of relapse (CIR), a poor 5-year event-free survival (EFS) rate, and a poor 5-year overall survival (OS) rate. The GSEA revealed that high-expression PGK1 in AML was associated with many pathways including cytosolic DNA sensing, pentose phosphate, base excision repair and DNA replication. In vitro, the transfected U937 and K562 cells with PGK1 knock-down showed decreased cell viability and increased apoptotic rate. PGK1 inhibition could greatly decrease the half maximal inhibitory concentrations (IC50) of cytarabine (Ara-C) and daunorubicin (DNR) in U937 and K562 cell lines.Conclusions: High-expression PGK1 was associated with poor prognosis in AML. PGK1 may serve to predict the AML progression and provide a novel therapeutic target for AML.

Repeat to Gene Expression Ratios in Leukemic Blast Cells Can Stratify Risk Prediction in Acute Myeloid Leukemia

BackgroundRepeat elements constitute a large proportion of the human genome and recent evidence indicates that repeat element expression has functional roles in both physiological and pathological states. Specifically for cancer, transcription of endogenous retrotransposons is often suppressed in order to attenuate an anti-tumor immune response, whereas aberrant expression of heterochromatin-derived satellite RNA has been identified as a tumor driver. These insights demonstrate separate functions for the dysregulation of distinct repeat subclasses in either the attenuation or progression of human solid tumors. For hematopoietic malignancies, such as AML, only very few studies on the expression/dysregulation of repeat elements were done. MethodsTo study the expression of repeat elements in acute myeloid leukemia (AML), we performed total-RNA sequencing of healthy CD34+ cells and of leukemic blast cells from primary AML patient material. We also developed an integrative bioinformatic approach that can quantify the expression of repeat transcripts from all repeat subclasses (SINE/ALU, LINE and ERV elements and satellite repeats) in relation to the expression of gene and other non-repeat transcripts. This novel approach can be used as an instructive signature (‘rep/gene’ ratio) for repeat element expression and has been extended to the analysis of poly(A)-RNA sequencing datasets from Blueprint and TCGA consortia that together comprise 120 AML patient samples. ResultsWe identified that repeat element expression is generally down-regulated during hematopoietic differentiation and that relative changes in repeat to gene expression (i.e. ‘rep/gene’ ratios) can stratify risk prediction of AML patients and correlate with overall survival probabilities. A high repeat to gene expression ratio identifies AML patient subgroups with a favorable prognosis, whereas a low repeat to gene expression is prevalent in AML patient subgroups with a poor prognosis. ConclusionsWe developed an integrative bioinformatic approach that defines a general model for the analysis of repeat element dysregulation in physiological and pathological development. We find that changes in repeat to gene expression (‘rep/gene’ ratios) correlate with hematopoietic differentiation and can sub-stratify AML patients into low-risk and high-risk subgroups. Thus, the definition of a ‘rep/gene’ expression ratio can serve as a valuable biomarker for AML and could also provide insights into differential patient response to epigenetic drug treatment.

Clinical Impact of CD25/CD123 Coexpression in Adult B-Cell Acute Lymphoblastic Leukemia Patients

This study aimed to determine the clinical impact of CD25+/CD123+ coexpression in adult B-cell acute lymphoblastic leukemia (B-ALL) cases. One hundred and twenty newly diagnosed B-ALL patients (≤60 years old) were included in this study. CD123 and CD25 expression on leukemic blast cells were assessed using flow cytometry. CD25+/CD123+ coexpression was detected in 40/120 B-ALL patients (33.3%). All B-ALL patients showed CD25+/CD123+ coexpression had lower induction of remission response and shorter overall survival as compared to B-ALL cases lacking coexpression. In conclusion, CD25+/CD123+ positive coexpression is a reliable flow cytometry marker for prediction of the outcome of adult B-ALL patients and could be used as a novel parameter for risk stratification of adult B-ALL cases.