Comparison of promoter DNA methylation and expression levels of genes encoding CCAAT/enhancer binding proteins in AML patients

The function and regulation of CCAAT/enhancer binding protein ε

In recent years, studies on the structure, function, and regulation of the C/EBPε gene have become an essential topic in the field of many diseases. CCAAT/enhancer-binding protein ε (C/EBPε) is the fifth member of the transcription factor CCAAT/C/EBP family of transcription factors. It plays crucial roles in cell proliferation, differentiation, immunity, energy metabolism, and hematopoiesis. C/EBPε plays essential roles in regulating the hematopoietic system, including myeloid cell development and maturation, participation in the body’s immune responses, and prevention of infections. C/EBPε function is regulated by phosphorylation, acetylation, methylation, and other types of genes. This review related to C/EBPε structure, function and regulation provides a theoretical basis for subsequent research in this area. C/EBPε is an emerging therapeutic target and thus provides new strategies for disease prevention and control.

The Dual Role of C/EBPδ in Cancer

CCAAT/Enhancer-Binding Protein delta (C/EBPδ) is a transcription factor involved in differentiation and inflammation. While sparsely expressed in adult tissues, aberrant expression of C/EBPδ has been associated with different cancers. Initially, re-expression of C/EBPδ in cell cultures limited tumor cell proliferation, assigning it a tumor suppressor role. However, opposing observations were made in pre-clinical models and patients, suggesting that C/EBPδ not only mediates cell proliferation but dictates a broader spectrum of tumorigenesis-related effects. It is now widely accepted that C/EBPδ contributes to an inflammatory, tumor-promoting microenvironment, aids hypoxia adaption and contributes to the recruitment of blood vessels for improved nutrient supply to tumor cells and facilitated extravasation. This review summarizes the work published on this transcription factor in the field of cancer over the past decade. It points out areas in which a consensus on C/EBPδ's role appears to emerge and seek to explain seemingly contradictory results.

Novel insights of acute myeloid leukemia with CEBPA deregulation: Heterogeneity dissection and re-stratification

Acute myeloid leukemia with bi-allelic CEBPA mutation was categorized as an independent disease entity with favorable prognosis, however, recent researches have revealed huge heterogeneity within this disease group, and for some patients, relapse remained a major cause of treatment failure. Further risk stratification is essentially needed. Here by reviewing the latest literature, we summarized the characteristics of CEBPA mutation profiles and clinical features, with a special intention of dissecting the heterogeneity within the seemingly homogeneous AML with bi-allelic CEBPA mutations. Specifically, non-classical CEBPA mutation, miscellaneous companion genetic aberrations and the presence of germline CEBPA mutation are three major sources of heterogeneity. Identifying these factors can help us predict patients at a higher risk of relapse, for whom aggressive treatment may be recommended. Novel therapeutic approaches regarding manipulating potentially druggable targets as well as the debate over post remission consolidation regimens has also been discussed.

BGN and COL11A1 Regulatory Network Analysis in Colorectal Cancer (CRC) Reveals That BGN Influences CRC Cell Biological Functions and Interacts with miR-6828-5p

Purpose

We explored specific expression profiles of BGN and COL11A1 genes and studied their biological functions in CRC using bioinformatics tools.

Patients and Methods

A total of 68 pairs of cancer and non-cancerous tissues from CRC patients were enrolled in this study. Methods we used in this articles including: qRT-PCR, Western blot analysis, ELISA, GO and KEGG regulatory network analysis, tumor infiltration, luciferase reporter-based protein and etc.

Results

According to The Cancer Genome Atlas (TCGA) data, BGN and COL11A1 expression levels were significantly higher in CRC patient samples than in samples from healthy controls. Moreover, levels were much higher in late-stage CRC than in early-stage disease, warranting evaluation of these genes as CRC prognostic biomarkers. Subsequently, qRT-PCR, Western blot analysis, and ELISA results obtained from analyses of CRC cells, tissues, and patient sera aligned with TCGA results. GO and KEGG regulatory network analysis revealed BGN- and COL11A1-associated genes that were functionally related to extracellular matrix (ECM) receptor pathway activation, with transcription factor genes RELA and NFKB1 positively associated with BGN expression and CEBPZ and SIRT1 with COL11A1 expression. Meanwhile, BGN and COL11A1 expression were separately and significantly correlated to tumor infiltration by six immune cell types. Additionally, kinase genes PLK1 and LYN appeared to be downstream targets of differentially expressed BGN and COL11A1, respectively. In addition, the expression of PLK1 mRNA was down-regulated while BGN was down-regulated. Finally, BGN effects on CRC cell proliferation, cycle, apoptosis, invasion, and migration were studied using molecular biological methods, including luciferase reporter-based protein analysis, qRT-PCR, and Western blot results, which revealed that miR-6828-5p may regulate BGN expression.

Conclusion

We speculate that the use of BGN and COL11A1 as CRC biomarkers would improve CRC staging, while also providing several novel targets for use in the development of more effective CRC treatments.

Prognostic role of ACTL10 in Cytogenetic Normal Acute Myeloid Leukemia

ACTL10 is a member of the actin family; however, despite previous studies suggesting that certain proteins in this family may be related to the pathogenesis of leukemia, to the best of our knowledge, no studies to date have demonstrated any association between ACTAL10 and leukemia. Thus, the present study aimed to determine the association between ACTL10 expression levels, DNA methylation levels and the clinical prognosis in cytogenic normal acute myeloid leukemia (CN-AML). Data from seventy-five patients with CN-AML and patients with AML treated with chemotherapy or allogeneic hematopoietic stem cell transplantation were obtained from The Cancer Genome Atlas (TCGA) dataset and were used to analyze the clinical prognosis of ACTL10 RNA expression levels and DNA methylation levels. In addition, the study also investigated the combined clinical prognosis of ACTL10 RNA expression levels and ACTL10 DNA methylation levels in 74 patients with CN-AML from the TCGA dataset. ACTL10 RNA expression levels were observed to be highly expressed in patients with CD34⁺/CD38⁺ AML (P<0.01). Both ACTL10 RNA expression levels and DNA methylation were found to be independent prognostic factors for patients with CN-AML; patients with CN-AML in the ACTL10 RNA-high expression group had an increased EFS (P=0.0016) and OS (P=0.014) and patients in ACTL10 DNA methylation-low group also demonstrated a long EFS (P<0.0001) and OS (P=0.004). Notably, integrating ACTL10 RNA expression levels and ACTL10 DNA methylation levels could more accurately predict the prognosis of patients with CN-AML (EFS and OS, P<0.0001). In conclusion, the findings of the present study suggested that the high RNA expression levels and low DNA methylation levels of ACTL10 may predict a good prognosis in patients with CN-AML.

N6-Methyladenosine (m6A): A Promising New Molecular Target in Acute Myeloid Leukemia

Recent studies have uncovered an important role for RNA modifications in gene expression regulation, which led to the birth of the epitranscriptomics field. It is now acknowledged that RNA modifiers play a crucial role in the control of differentiation of stem and progenitor cells and that changes in their levels are a relevant feature of different types of cancer. To date, among more than 160 different RNA chemical modifications, the more relevant in cancer biology is the reversible and dynamic N⁶-methylation of adenosine, yielding N⁶-methyladenosine (m⁶A). m⁶A is the more abundant internal modification in mRNA, regulating the expression of the latter at different levels, from maturation to translation. Here, we will describe the emerging role of m⁶A modification in acute myeloid leukemia (AML), which, among first, has demonstrated how mis-regulation of the m6A modifying system can contribute to the development and progression of cancer. Moreover, we will discuss how AML is paving the way to the development of new therapeutic options based on the inhibition of m⁶A deposition.

High methylation of the 4-aminobutyrate aminotransferase gene predicts a poor prognosis in patients with myelodysplastic syndrome

In our previous study, the 4‑aminobutyrate aminotransferase (ABAT) gene was screened and selected as a target gene that may affect the prognosis of myelodysplastic syndrome (MDS). The present study aimed to determine the prognostic value of ABAT in 152 patients with MDS, 29 patients with acute myeloid leukemia (AML) and 40 controls, by detecting the expression and methylation levels of the ABAT gene. In patients with MDS, the expression levels of ABAT were significantly reduced compared with in the controls (P<0.0001), and the degree of DNA methylation was increased in MDS subjects (P<0.0001). Age, hemoglobin level, marrow blasts, International Prognostic Scoring System karyotype, and the expression and methylation levels of ABAT were associated with overall survival (OS), as determined by univariate analysis. Multivariate analysis revealed that older age, higher marrow blasts and higher methylation percentage were independent risk factors for OS. In addition, a functional study demonstrated that ABAT gene silencing increased cell apoptosis and blocked the G1/S phase in SKM‑1 and THP‑1 human leukemia cells. A γ‑aminobutyrate aminotransferase inhibitor also blocked the G1/S phase; however, it had no effect on cell apoptosis. In conclusion, the present study demonstrated that ABAT methylation served an essential role in the progression of MDS and therefore may be considered an indicator of poor prognosis for hematological malignancies.

N6-Methyladenosine Role in Acute Myeloid Leukaemia

We are currently assisting in the explosion of epitranscriptomics, which studies the functional role of chemical modifications into RNA molecules. Among more than 100 RNA modifications, the N6-methyladenosine (m⁶A), in particular, has attracted the interest of researchers all around the world. m⁶A is the most abundant internal chemical modification in mRNA, and it can control any aspect of mRNA post-transcriptional regulation. m⁶A is installed by “writers”, removed by “erasers”, and recognized by “readers”; thus, it can be compared to the reversible and dynamic epigenetic modifications in histones and DNA. Given its fundamental role in determining the way mRNAs are expressed, it comes as no surprise that alterations to m⁶A modifications have a deep impact in cell differentiation, normal development and human diseases. Here, we review the proteins involved in m⁶A modification in mammals, m⁶A role in gene expression and its contribution to cancer development. In particular, we will focus on acute myeloid leukaemia (AML), which provides an initial indication of how alteration in m⁶A modification can disrupt normal cellular differentiation and lead to cancer.

C/EBPα deregulation as a paradigm for leukemogenesis

Myeloid master regulator CCAAT enhancer-binding protein alpha (C/EBPα) is deregulated by multiple mechanisms in leukemia. Inhibition of C/EBPα function plays pivotal roles in leukemogenesis. While much is known about how C/EBPα orchestrates granulopoiesis, our understanding of molecular transformation events, the role(s) of cooperating mutations and clonal evolution during C/EBPα deregulation in leukemia remains elusive. In this review, we will summarize the latest research addressing these topics with special emphasis on CEBPA mutations. We conclude by describing emerging therapeutic strategies to restore C/EBPα function.

CEBPD amplification and overexpression in urothelial carcinoma: a driver of tumor metastasis indicating adverse prognosis

The molecular aberrations responsible for the progression of urothelial carcinoma (UC) remain largely obscure. To search candidate driver oncogenes in UC, we performed array-based genomic hybridization (aCGH) on 40 UBUC samples. Amplification of 8q11.21 was preferentially identified in patients who developed disease-specific death (53.8%) and distal metastasis (50.0%) but was barely detected in non-eventful cases (3.7% and 0%, respectively). In order to quantify the expression of candidate genes harbored in 8q11.21, laser-capture microdissection coupled with RT-PCR was performed on 32 of the 40 cases submitted to aCGH. With this, we identified CEBPD mRNA expression as most significantly associated with gains of 8q11.21, suggesting amplification-driven expression. By performing CEBPD-specific FISH and immunohistochemistry on 295 UBUCs, we confirmed CEBPD amplification (21.3%) and overexpression (29.8%) were strongly related to each other (p<0.001). Moreover, both were associated with adverse clinicopathologic features and worse outcomes. Furthermore, the clinical significance of CEBPD expression was also confirmed in an independent cohort comprised of 340 UCs from the upper urinary tract. Interestingly, CEBPD knockdown suppressed cell proliferation, migration and, most significantly, cell invasion ability in UC cells. The latter phenotype is attributed to downregulation of MMP2 as identified by RT2 Profiler PCR array. Moreover, expression of CEBPD significantly enhanced MMP2 expression and transcriptional activation by directly binding to its promoter region, as confirmed by promoter reporter assay and chromatin immunoprecipitation assay. Conclusively, CEBPD amplification is a mechanism driving increased mRNA and protein expression that confers aggressiveness in UC through MMP2-mediated cell invasiveness.

Natural compounds and pharmaceuticals reprogram leukemia cell differentiation pathways

In addition to apoptosis resistance and cell proliferation capacities, the undifferentiated state also characterizes most cancer cells, especially leukemia cells. Cell differentiation is a multifaceted process that depends on complex regulatory networks that involve transcriptional, post-transcriptional and epigenetic regulation of gene expression. The time- and spatially-dependent expression of lineage-specific genes and genes that control cell growth and cell death is implicated in the process of maturation. The induction of cancer cell differentiation is considered an alternative approach to elicit cell death and proliferation arrest. Differentiation therapy has mainly been developed to treat acute myeloid leukemia, notably with all-trans retinoic acid (ATRA). Numerous molecules from diverse natural or synthetic origins are effective alone or in association with ATRA in both in vitro and in vivo experiments. During the last two decades, pharmaceuticals and natural compounds with various chemical structures, including alkaloids, flavonoids and polyphenols, were identified as potential differentiating agents of hematopoietic pathways and osteogenesis.

C/EBPα in normal and malignant myelopoiesis

CCAAT/enhancer binding protein α (C/EBPα) dimerizes via its leucine zipper (LZ) domain to bind DNA via its basic region and activate transcription via N-terminal trans-activation domains. The activity of C/EBPα is modulated by several serine/threonine kinases and via sumoylation, its gene is activated by RUNX1 and additional transcription factors, its mRNA stability is modified by miRNAs, and its mRNA is subject to translation control that affects AUG selection. In addition to inducing differentiation, C/EBPα inhibits cell cycle progression and apoptosis. Within hematopoiesis, C/EBPα levels increase as long-term stem cells progress to granulocyte-monocyte progenitors (GMP). Absence of C/EBPα prevents GMP formation, and higher levels are required for granulopoiesis compared to monopoiesis. C/EBPα interacts with AP-1 proteins to bind hybrid DNA elements during monopoiesis, and induction of Gfi-1, C/EBPε, KLF5, and miR-223 by C/EBPα enables granulopoiesis. The CEBPA ORF is mutated in approximately 10 % of acute myeloid leukemias (AML), leading to expression of N-terminally truncated C/EBPαp30 and C-terminal, in-frame C/EBPαLZ variants, which inhibit C/EBPα activities but also play additional roles during myeloid transformation. RUNX1 mutation, CEBPA promoter methylation, Trib1 or Trib2-mediated C/EBPαp42 degradation, and signaling pathways leading to C/EBPα serine 21 phosphorylation reduce C/EBPα expression or activity in additional AML cases.