Epigenetic silencing of AKAP12 in juvenile myelomonocytic leukemia

Abstract

A-kinase anchor protein 12 (AKAP12) is a regulator of protein kinase A and protein kinase C signaling, acting downstream of RAS. Epigenetic silencing of AKAP12 has been demonstrated in different cancer entities and this has been linked to the process of tumorigenesis. Here, we used quantitative highresolution DNA methylation measurement by MassARRAY to investigate epigenetic regulation of all three AKAP12 promoters (i.e., a, b, and g) within a large cohort of juvenile myelomonocytic leukemia (JMML) patient samples. The AKAP12a promoter shows DNA hypermethylation in JMML samples, which is associated with decreased AKAP12a expression. Promoter methylation of AKAP12a correlates with older age at diagnosis, elevated levels of fetal hemoglobin and poor prognosis. In silico screening for transcription factor binding motifs around the sites of most pronounced methylation changes in the AKAP12a promoter revealed highly significant scores for GATA-2/-1 sequence motifs. Both transcription factors are known to be involved in the haematopoietic differentiation process. Methylation of a reporter construct containing this region resulted in strong suppression of AKAP12 promoter activity, suggesting that DNA methylation might be involved in the aberrant silencing of the AKAP12 promoter in JMML. Exposure to DNMT-and HDAC-inhibitors reactivates AKAP12a expression in vitro, which could potentially be a mechanism underlying clinical treatment responses upon demethylating therapy. Together, these data provide evidence for epigenetic silencing of AKAP12a in JMML and further emphasize the importance of dysregulated RAS signaling in JMML pathogenesis.

Ras-pathway mutation patterns define epigenetic subclasses in juvenile myelomonocytic leukemia

“…Evidence from the literature suggests that oncogenic RAS-signaling is able to modify epigenetic patterns [16][17][18] . Indeed, investigations of DNA methylation in JMML at the level of candidate gene promoters (AKAP12, BMP4, CALCA, CDKN2A, RARB, and RASA4) identified DNA hypermethylation to be associated with poor clinical outcome [19][20][21] . Still, to date, a comprehensive characterization of the DNA methylome in JMML is missing.…”

ASB1 differential methylation in ischaemic cardiomyopathy: relationship with left ventricular performance in end‐stage heart failure patients

“…1,2 However, apart from these global changes, there are other omic approaches revealing insights in the regulation of expression patterns in the disease. Epigenomics has allowed the identification of epigenetic signatures in human diseases including different types of cancer, [3][4][5] neurological disorders, 6,7 or infections. 8 There are also some evidences of their role in cardiovascular diseases.…”

Panobinostat inhibits the proliferation of CD34+CD38−cells under stimulation of hematopoietic growth factors on AGM‐S3 cells in juvenile myelomonocytic leukemia

“…They found that a high methylation phenotype characterizes an aggressive biologic variant of JMML and is an important molecular predictor of the outcome. Epigenetic silencing also occurs in the a‐kinase anchor protein 12 ( AKAP12 ) gene, whose product functions as a regulator of protein kinase A and C signaling, acting downstream of RAS . Cseh et al.…”

“…Epigenetic silencing also occurs in the a-kinase anchor protein 12 (AKAP12) gene, whose product functions as a regulator of protein kinase A and C signaling, acting downstream of RAS. 8 Cseh et al reported that complete clinical, cytogenetic, and/or molecular genetic remissions before allogeneic hematopoietic stem cell transplantation were achieved by treatment with low-dose azacytidine (a DNA methyltransferase inhibitor) in three of 12 patients with JMML. 9 Histone deacetylase (HDAC) inhibitors are a class of antineoplastic agents targeting the epigenome, specifically chromatin remodeling, resulting in modulation of genes responsible for apoptosis and cell cycle regulation, and also hyperacetylation of many nonhistone proteins.…”