JIB-04, a Pan-Inhibitor of Histone Demethylases, Targets Histone-Lysine-Demethylase-Dependent AKT Pathway, Leading to Cell Cycle Arrest and Inhibition of Cancer Stem-Like Cell Properties in Hepatocellular Carcinoma Cells

Metabolic modulation of histone acetylation mediated by HMGCL activates the FOXM1/β-catenin pathway in glioblastoma

BACKGROUND

Altered branched-chain amino acid (BCAA) metabolism modulates epigenetic modification, such as H3K27ac in cancer, thus providing a link between metabolic reprogramming and epigenetic change, which are prominent hallmarks of glioblastoma multiforme (GBM). Here, we identified mitochondrial 3-hydroxymethyl-3-methylglutaryl-CoA lyase (HMGCL), an enzyme involved in leucine degradation, promoting GBM progression and glioma stem cell (GSC) maintenance.

METHODS

In silico analysis was performed to identify specific molecules involved in multiple processes. Glioblastoma multiforme cells were infected with knockdown/overexpression lentiviral constructs of HMGCL to assess malignant performance in vitro and in an orthotopic xenograft model. RNA sequencing was used to identify potential downstream molecular targets.

RESULTS

HMGCL, as a gene, increased in GBM and was associated with poor survival in patients. Knockdown of HMGCL suppressed proliferation and invasion in vitro and in vivo. Acetyl-CoA was decreased with HMGCL knockdown, which led to reduced NFAT1 nuclear accumulation and H3K27ac level. RNA sequencing-based transcriptomic profiling revealed FOXM1 as a candidate downstream target, and HMGCL-mediated H3K27ac modification in the FOXM1 promoter induced transcription of the gene. Loss of FOXM1 protein with HMGCL knockdown led to decreased nuclear translocation and thus activity of β-catenin, a known oncogene. Finally, JIB-04, a small molecule confirmed to bind to HMGCL, suppressed GBM tumorigenesis in vitro and in vivo.

CONCLUSIONS

Changes in acetyl-CoA levels induced by HMGCL altered H3K27ac modification, which triggers transcription of FOXM1 and β-catenin nuclear translocation. Targeting HMGCL by JIB-04 inhibited tumor growth, indicating that mediators of BCAA metabolism may serve as molecular targets for effective GBM treatment.

The JMJD family of histone demethylase and their intimate links to cardiovascular disease

The incidence rate and mortality rate of cardiovascular disease rank first in the world. It is associated with various high-risk factors, and there is no single cause. Epigenetic modifications, such as DNA methylation or histone modification, actively participate in the initiation and development of cardiovascular diseases. Histone lysine methylation is a type of histone post-translational modification. The human Jumonji C domain (JMJD) protein family consists of more than 30 members. JMJD proteins participate in many key nuclear processes and play a key role in the specific regulation of gene expression, DNA damage and repair, and DNA replication. Importantly, increasing evidence shows that JMJD proteins are abnormally expressed in cardiovascular diseases, which may be a potential mechanism for the occurrence and development of these diseases. Here, we discuss the key roles of JMJD proteins in various common cardiovascular diseases. This includes histone lysine demethylase, which has been studied in depth, and less-studied JMJD members. Furthermore, we focus on the epigenetic changes induced by each JMJD member, summarize recent research progress, and evaluate their relationship with cardiovascular diseases and therapeutic potential.

METTL3 facilitates stemness properties and tumorigenicity of cancer stem cells in hepatocellular carcinoma through the SOCS3/JAK2/STAT3 signaling pathway

Liver cancer stem cells (LCSCs) contribute to tumor recurrence and cancer cell proliferation in patients with hepatocellular carcinoma (HCC). METTL3-catalyzed m6A modification is relevant to the cancer stem cell (CSC) phenotype, including LCSCs. LCSCs were isolated from MHCC-97H and HepG2 cells through flow cytometry. UALCAN data were used to analyze the expression of METTL3 in liver hepatocellular carcinoma (LIHC) tissues. Loss- and gain-of-function experiments were utilized to assess the biological effects of METTL3 and SOCS3 on the proliferation and stemness phenotypes in vitro and in vivo. The mechanisms underlying the impact of METTL3 were explored using qPCR, MeRIP-qPCR, dual-luciferase reporter, and western blot assays. METTL3 was significantly upregulated in LIHC tissues according to the UALCAN database. METTL3 was highly expressed in LIHC and was significantly correlated with individual cancer stage, tumor grade and lymph node metastasis. Patients with low METTL3 expression had a longer overall survival time based on the data from UALCAN. In addition, the level of METTL3 was enhanced in LCSCs and decreased in non-LCSCs compared to HCC cells. Moreover, overexpression of METTL3 stimulated the proliferation and stemness of LCSCs in vitro and in vivo, while loss of METTL3 impeded it. Bioinformatics analysis combined with validation experiments determined that m6A was modified by METTL3-targeting SOCS3 mRNA. METTL3 had side effects regarding the stability of SOCS3 mRNA. SOCS3 overexpression impaired and SOCS3 depletion facilitated the development of LCSCs via the JAK2/STAT3 pathway. Furthermore, METTL3 depletion suppressed proliferation and stemness in LCSCs, which was restored by SOCS3 knockdown or colivelin treatment. We discovered that METTL3 facilitated the stemness and tumorigenicity of LCSCs by modifying SOCS3 mRNA with m6A.

Methylation of the JMJD2B epigenetic regulator differentially affects its ability to coactivate the ETV1 and JUN transcription factors

OBJECTIVES

Jumonji C domain-containing (JMJD) 2B (JMJD2B) is a transcriptional cofactor and histone demethylase that is involved in prostate cancer formation. However, how its function is regulated by posttranslational modification has remained elusive. Hence, we examined if JMJD2B would be regulated by lysine methylation.

METHODS

Through in vitro methylation assays and Western blotting with methyl-lysine specific antibodies, we analyzed lysine methylation within JMJD2B. Identified methylated lysine residues were mutated to arginine residues and the respective impact on JMJD2B transcriptional activity measured with a reporter gene assay in human LNCaP prostate cancer cells.

RESULTS

We discovered that JMJD2B is methylated on up to six different lysine residues. Further, we identified the suppressor of variegation 3-9/enhancer of zeste/trithorax (SET) domain-containing protein 7/9 (SET7/9) as the methyltransferase being responsible for this posttranslational modification. Mutating the methylation sites in JMJD2B to arginine residues led to diminished coactivation of the Ju-nana (JUN) transcription factor, which is a known oncogenic protein in prostate tumors. In contrast, methylation of JMJD2B had no impact on its ability to coactivate another transcription factor associated with prostate cancer, the DNA-binding protein E26 transformation-specific (ETS) variant 1 (ETV1). Consistent with a potential joint action of JMJD2B, SET7/9 and JUN in prostate cancer, the expression of JMJD2B in human prostate tumors was positively correlated with both SET7/9 and JUN levels.

CONCLUSIONS

The identified SET7/9-mediated methylation of JMJD2B appears to impact its cooperation with selected interacting transcription factors in prostate cancer cells. Given the implicated roles of JMJD2B beyond prostate tumorigenesis, SET7/9-mediated methylation of JMJD2B possibly also influences the development of other cancers, while its impairment might have relevance for obesity or a global developmental delay that can be elicited by reduced JMJD2B activity.