Epigenetic regulation of HOTAIR in advanced chronic myeloid leukemia.

Purpose: Chronic myeloid leukemia (CML) accounts for ~10% of leukemia cases, and its progression involves epigenetic gene regulation. This study investigated epigenetic regulation of HOTAIR and its target microRNA, miR-143, in advanced CML.

Patients and methods: We first isolated bone marrow mononuclear cells from 70 patients with different phases of CML and from healthy donors as normal control; we also cultured K562 and KCL22 cells, treated with demethylation drug; MTT assay, flow cytometry, quantitative real-time polymerase chain reaction (qPCR), methylation-specific polymerase chain reaction (MSP), Western blot, luciferase assay, RNA pull-down assay and RNA-binding protein immunoprecipitation (RIP) assay were performed.

Result: As measured by qPCR, HOTAIR expression in K562 cells, KCL22 cells, and samples from cases of advanced-stage CML increased with levels of several DNA methyltransferases and histone deacetylates, including DNMT1, DNMT3A, HDAC1, EZH2, and LSD1, and miR-143 levels were decreased and HOTAIR levels were increased. Treatment with 5-azacytidine, a DNA methylation inhibitor, decreased DNMT1, DNMT3A, HDAC1, EZH2, LSD1 mRNA, protein levels, and HOTAIR mRNA levels but increased miR-143 levels. HOTAIR knockdown and miR-143 overexpression both inhibited proliferation and promoted apoptosis in KCL22 and K562 cells through the PI3K/AKT pathway. RNA pull-down, mass spectrometry, and RIP assays showed that HOTAIR interacted with EZH2 and LSD1. A dual-luciferase assay demonstrated that HOTAIR interacted with miR-143.

Conclusion: Our findings demonstrate the key epigenetic interactions of HOTAIR related to CML progression and suggest HOTAIR as a potential therapeutic target for advanced CML. Furthermore, our results support the use of demethylation drugs as a CML treatment strategy.