ALKBH5 Functions As an Oncogene in Multiple Myeloma

Background: RNA N 6-methyladenosine (m 6A) plays a critical role in regulating gene expression and determining cell fate. The dysregulation of m 6A modulators, including α-ketoglutarate-dependent dioxygenase AlkB homolog 5 (ALKBH5), has been reported to promote tumor development through their enzymatic function. However, the functions of mRNA m 6A and its modulators in multiple myeloma (MM) are largely unknown. Methods: We queried publicly available MM datasets to study the expression profile of m 6A modulators (METTL3, METTL14, WTAP, FTO, and ALKBH5) in MM and their relationships with clinical outcomes in patients with MM. Both gain- and loss-of-function studies were performed to investigate the role of ALKBH5 in MM. The cell proliferation assay, colony formation assay, Annexin V apoptosis analysis, and 5-ethynyl-2′-deoxyuridine (EdU) assay were performed to evaluate the functions of ALKBH5 in MM in vitro. Human MM cell line xenograft models were constructed to examine the effects of ALKBH5 knockdown or overexpression on MM growth in vivo. The rescue assay using catalytically inactive mutant ALKBH5-H204A was conducted to determine whether demethylation activity was required for the function of ALKBH5 in MM. Then, we performed RNA sequencing and m 6A sequencing to explore the key targets that mediated ALKBH5 function in MM. We investigated the gene regulatory mechanism of ALKBH5 in MM by m 6A immunoprecipitation assay, RNA immunoprecipitation assay, RNA decay assay, dual-luciferase reporter assay, and so forth. Gene set enrichment analysis and Western blotting were employed to determine the downstream signaling pathways regulated by ALKBH5 and the recognized target. Results: ALKBH5 was overexpressed in MM and associated with a poor prognosis in patients with MM. The increased ALKBH5 expression was required for the survival and growth of MM cells in vitro and in vivo. Mechanistically, m 6A demethylation activity was required for ALKBH5 to exert tumorigenic effects in MM. Tumor necrosis factor (TNF) receptor-associated factor 1 (TRAF1) was identified as a functionally important target of ALKBH5. ALKBH5 regulated TRAF1 expression via affecting mRNA stability of TRAF1 in an m 6A- and YTHDF2-dependent manner. ALKBH5 promoted MM cell growth and survival partly through TRAF1-mediated activation of NF-κB and MAPK signaling pathways. Conclusion: Our findings showed that ALKBH5 played an oncogenic role in MM and highlighted that ALKBH5 could potentially be a novel therapeutic target in MM. Disclosures No relevant conflicts of interest to declare.

KDM2A Targets PFKFB3 for Ubiquitylation to Inhibit the Proliferation and Angiogenesis of Multiple Myeloma Cells

The lysine demethylase KDM2A (also known as JHDM1A or FBXL11) demethylates histone H3 at lysine K36 which lead to epigenetic regulation of cell proliferation and tumorigenesis. However, many biological processes are mediated by KDM2A independently by its histone demethylation activity. In the present study, we aimed to characterize the functional significance of KDM2A in multiple myeloma (MM) disease progression. Specifically, we defined that one of the key enzymes of glycolysis PFKFB3 (6-phosphofructo-2-kinase) is ubiquitylated by KDM2A which suppresses MM cell proliferation. Previous study showed that KDM2A and PFKFB3 promoted angiogenesis in various tumor cells. We further reveal that KDM2A targets PFKFB3 for ubiquitination and degradation to inhibit angiogenesis. Several angiogenic cytokines are also downregulated in MM. Clinically, MM patients with low KDM2A and high PFKFB3 levels have shown worse prognosis. These results reveal a novel function of KDM2A through ubiquitin ligase activity by targeting PFKFB3 to induce proliferation, glycolysis and angiogenesis in MM cells. The data provides a new potential mechanism and strategy for MM treatment.

Histone demethylase JMJD3 disrupts spectrin-dependent cytoskeleton in Pancreatic Ductal Adenocarcinoma cells by regulating H exokinase domain containing 1 expression

Background: JMJD3 is a jmjd domain containing histone demethylase which can remove methyl groups from lysine 27 of histone 3 (H3K27) to active histone methylated genes. Previous studies have demonstrated that JMJD3 played a crucial role in inflammation. Methods: Our study showed that JMJD3 was significantly down-regulated in pancreatic ductal adenocarcinoma (PDAC) cell lines and tissues. Restored expression of JMJD3 inhibited oncogenic phenotypes of PDAC cells, including cell proliferation, cell migration, and in vivo tumorigenicity, indicating a tumor suppressive role. Gene-expression microarray revealed that Hexokinase domain containing 1 (HKDC1) was one of the JMJD3 downstream targets. Results: The expression of JMJD3 and HKDC1 in PDAC tissues was positively correlated. High H3K27 tri-methylation (H3K27me3) status in HKDC1 gene was attenuated by ectopic expression of JMJD3 in PDAC cells, suggested that JMJD3 regulated HKDC1 expression by histone demethylation activity. The tumor suppressive role of HKDC1 in PDAC was also proved. Moreover, HKDC1 was demonstrated to competitively bind to spectrin beta Ⅱ to induce cytoskeleton disruption, which may contribute to tumor suppression. Conclusion: Taken together, our study indicates that JMJD3 may disrupt spectrin-dependent cytoskeleton via activation of HKDC1 to suppress PDAC.

Chemistry and Pharmacology of Luliconazole (Imidazole Derivative): A Novel Bioactive Compound to Treat Fungal Infection-A Mini Review

Background: Currently, ringworm treatment drugs include two major categories: first, propylene amine drugs, such as terbinafine, butenafine and naftifine, which exert their bactericidal effects through inhibiting squalene cyclase, causing the lack of ergosterol and accumulation of squalene. The second category of imidazole drugs includes miconazole, econazole, clotrimazole, ketoconazole and bifonazole. Mechanism: These synthetic antifungal agents exhibits their action by inhibiting the lanosterol 14α- demethylation activity of fungal cell, leading to the prevention of the ergosterol synthesis of cell membrane, changing the cell membrane permeability, and resulting in the loss of important intracellular fungal material and causing fungal death. Applications: At present, Imidazole antifungal agents are commonly used drugs in clinical treatment of ringworm with extensive clinical applications. Conclusion: The present review covers the chemistry and detailed pharmacology aspects of luliconazole.

Antitumor Activity of Indole-3-carbinol in Breast Cancer Cells: Phenotype, Genetic Pattern, DNA Methylation Inversion

The effect of indole-3-carbinol on a number of functions and characteristics of MDA-MB-231 breast cancer cells and MCF-10A healthy breast tissue cells has been studied. It was shown that indole-3-carbinol significantly reduced the proliferation and migration of MDA-MB-231 cells and does not affect these functions in MCF-10A cells. Incubation of MDA-MB-231 tumor cells with indole-3-carbinol (100 uM) for 48 h resulted in a marked decrease in the expression of the Wnt cascade genes, CCND1 (by 28%), SP1 (by 44%), CDK6 (by 47%), as well as EGFR (by 64%) and FASN (by 22%) genes. Incubation of MCF-10A cell line under the same conditions induced a noticeable decrease in expression of only two genes, EGFR (by 16%) and CDK6 (by 9%). In addition, indole-3-carbinol was also shown to manifest a selective DNA demethylation activity in breast tumor cells and to reverse the process of abnormal methylation and functional blockage of the anti-tumor WIF1 gene. These data indicate that drags containing indole-3-carbinol as an active component can be potential regulators of epigenetic processes in the treatment of breast cancer and other tumors. indole-3-carbinol, breast cancer, epigenetics, Wnt

Extended Recognition of the Histone H3 Tail by Histone Demethylase KDM5A

ABSTRACTHuman lysine demethylase KDM5A is a chromatin modifying enzyme associated with transcriptional regulation due to its ability to catalyze removal of methyl groups from methylated lysine 4 of histone H3 (H3K4me3). Amplification of KDM5A is observed in a number of cancers, including breast cancer, prostate cancer, hepatocellular carcinoma, lung cancer and gastric cancer. In this study, we employed alanine scanning mutagenesis to investigate substrate recognition of KDM5A and identify the H3 tail residues necessary for KDM5A-catalyzed demethylation. Our data show that the H3Q5 residue is critical for substrate recognition by KDM5A. Our data also reveal that the protein-protein interactions between KDM5A and the histone H3 tail extend beyond the amino acids proximal to the substrate mark. Specifically, demethylation activity assays show that deletion or mutation of residues at positions 14-18 on the H3 tail results in an 8-fold increase in the KMapp compared to wild-type 18mer peptide, suggesting this distal epitope is important in histone engagement. Finally, we demonstrate that post-translational modifications on this distal epitope can modulate KDM5A-dependent demethylation. Our findings provide insights into H3K4-specific recognition by KDM5A as well as how chromatin context can regulate KDM5A activity and H3K4 methylation status.

Structural insights into FTO’s catalytic mechanism for the demethylation of multiple RNA substrates

FTO demethylates internal N6-methyladenosine (m6A) and N6,2′-O-dimethyladenosine (m6Am; at the cap +1 position) in mRNA, m6A and m6Am in snRNA, and N1-methyladenosine (m1A) in tRNA in vivo, and in vitro evidence supports that it can also demethylate N6-methyldeoxyadenosine (6mA), 3-methylthymine (3mT), and 3-methyluracil (m3U). However, it remains unclear how FTO variously recognizes and catalyzes these diverse substrates. Here we demonstrate—in vitro and in vivo—that FTO has extensive demethylation enzymatic activity on both internal m6A and cap m6Am. Considering that 6mA, m6A, and m6Am all share the same nucleobase, we present a crystal structure of human FTO bound to 6mA-modified ssDNA, revealing the molecular basis of the catalytic demethylation of FTO toward multiple RNA substrates. We discovered that (i) N6-methyladenine is the most favorable nucleobase substrate of FTO, (ii) FTO displays the same demethylation activity toward internal m6A and m6Am in the same RNA sequence, suggesting that the substrate specificity of FTO primarily results from the interaction of residues in the catalytic pocket with the nucleobase (rather than the ribose ring), and (iii) the sequence and the tertiary structure of RNA can affect the catalytic activity of FTO. Our findings provide a structural basis for understanding the catalytic mechanism through which FTO demethylates its multiple substrates and pave the way forward for the structure-guided design of selective chemicals for functional studies and potential therapeutic applications.