The lncRNA LAMP5-AS1 drives leukemia cell stemness by directly modulating DOT1L methyltransferase activity in MLL leukemia

• Published in: Journal of hematology and oncology Vol. 13; no. 1; p. 78
• Main Authors: Wang, Wen-Tao, Chen, Tian-Qi, Zeng, Zhan-Cheng, Pan, Qi, Huang, Wei, Han, Cai, Fang, Ke, Sun, Lin-Yu, Yang, Qian-Qian, Wang, Dan, Luo, Xue-Qun, Sun, Yu-Meng, Chen, Yue-Qin
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 17.06.2020; BioMed Central; BMC
• Subjects: Analysis; Animals; Antisense RNA; Antisense therapy; Cancer genetics; CD34 antigen; Cell cycle; Cell differentiation; Cell Self Renewal - genetics; Cell self-renewal; cell stemness; Child, Preschool; Chromatin; Cloning; DNA methylation; DOT1L; Electrophoretic mobility; Epigenetic inheritance; Epigenetics; Experiments; Female; Fluorescence in situ hybridization; Gene expression; Gene Expression Regulation, Leukemic - genetics; Genes; Genetic aspects; Genetic Vectors - genetics; H3K79 methylation; Health aspects; Hematology; Hematopoietic stem cells; Heterografts; Histone methyltransferase; Histone-Lysine N-Methyltransferase - genetics; Histone-Lysine N-Methyltransferase - metabolism; Histones; Histones - metabolism; Homeodomain Proteins - metabolism; Humans; Immunoprecipitation; Infant; Laboratory animals; LAMP5-AS1; Leukemia; Leukemia, Myeloid, Acute - enzymology; Leukemia, Myeloid, Acute - genetics; Leukemia, Myeloid, Acute - pathology; lncRNA; Lysine - metabolism; Lysosomal Membrane Proteins - genetics; Male; Methylation; Methyltransferases; Mice; Mice, Inbred NOD; Mice, SCID; MLL leukemia; Myeloid-Lymphoid Leukemia Protein - genetics; Neoplastic Stem Cells - enzymology; Oncogene Proteins, Fusion - genetics; Oncology; Patients; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma - enzymology; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma - genetics; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma - pathology; Primary Cell Culture; Progenitor cells; Protein Processing, Post-Translational; Proteins; Recombinant Fusion Proteins - metabolism; Ribonucleic acid; RNA; RNA Interference; RNA, Antisense - genetics; RNA, Messenger - genetics; RNA, Neoplasm - genetics; RNA, Small Interfering - genetics; RNA, Small Interfering - pharmacology; Specific Pathogen-Free Organisms; Stem cells; Therapeutic applications; Transcription; Transcription (Genetics); Transfer RNA; Tumor Cells, Cultured; Tumor Stem Cell Assay; Japan; China; United States > US; Germany; cell stemness; lncRNA; H3K79 methylation; LAMP5-AS1; DOT1L; MLL leukemia
• ISSN: 1756-8722; 1756-8722
• DOI: 10.1186/s13045-020-00909-y

Mixed-lineage leukemia (MLL) gene rearrangements trigger aberrant epigenetic modification and gene expression in hematopoietic stem and progenitor cells, which generates one of the most aggressive subtypes of leukemia with an apex self-renewal. It remains a challenge to directly inhibit rearranged MLL itself because of its multiple fusion partners and the poorly annotated downstream genes of MLL fusion proteins; therefore, novel therapeutic targets are urgently needed. qRT-PCR, receiver operating characteristic (ROC), and leukemia-free survival analysis were used to validate LAMP5-AS1 (LAMP5 antisense 1) expression and evaluate its clinical value. We performed in vitro and in vivo experiments to investigate the functional relevance of LAMP5-AS1 in MLL leukemia progression and leukemia cell stemness. RNA electrophoretic mobility shift assays (EMSA), histone methyltransferase assay, RNA pull-down assay, and RNA fluorescence in situ hybridization (FISH) were used to validate the relationship between LAMP5-AS1 and the methyltransferase activity of DOT1L. The downstream ectopic target genes of LAMP5-AS1/DOT1L were validated by the chromatin immunoprecipitation (ChIP) and western blot. We discovered that a long noncoding RNA (lncRNA) LAMP5-AS1 can promote higher degrees of H3K79 methylation, followed by upregulated expression of the self-renewal genes in the HOXA cluster, which are responsible for leukemia stemness in context of MLL rearrangements. We found that LAMP5-AS1 is specifically overexpressed in MLL leukemia patients (n = 58) than that in the MLL-wt leukemia (n = 163) (p < 0.001), and the patients with a higher expression level of LAMP5-AS1 exhibited a reduced 5-year leukemia-free survival (p < 0.01). LAMP5-AS1 suppression significantly reduced colony formation and increased differentiation of primary MLL leukemia CD34+ cells. Mechanistically, LAMP5-AS1 facilitated the methyltransferase activity of DOT1L by directly binding its Lys-rich region of catalytic domain, thus promoting the global patterns of H3K79 dimethylation and trimethylation in cells. These observations supported that LAMP5-AS1 upregulated H3K79me2/me3 and the transcription of DOT1L ectopic target genes. This is the first study that a lncRNA regulates the self-renewal program and differentiation block in MLL leukemia cells by facilitating the methyltransferase activity of DOT1L and global H3K79 methylation, showing its potential as a therapeutic target for MLL leukemia.