Combinations of HDAC inhibitor and PPAR agonist induce ferroptosis of leukemic stem cell-like cells in acute myeloid leukemia

Purpose: Leukemia stem cells (LSCs) are responsible for leukemia initiation, relapse, and therapeutic resistance. Therefore, the development of novel therapeutic approaches targeting LSCs is urgently needed for patients with AML. Methods: The LSCs-like cell lines (KG-1α and Kasumi-1), CD34+ primary AML cells purified from AML patients (n=23) treated with CS055 and/or chiglitazar and were analyzed for viability, death, and colony formation assay. We performed RNA-seq, Glutamate-Release, Intracellular-GSH, Lipid-ROS, transmission-electron-microscopy, Western-Blotting assay, and confirmed ferroptosis in LSCs-like cells. The luciferase-reporter, co-immunoprecipitation, HDAC3-shRNA/HDAC3/deacetylase-deficient LSCs-like cell lines, His-pull-down, and chromatin-immunoprecipitation assays performed to clarify the molecular mechanism of CS055/chiglitazar in LSCs-like cells. We also established CDX and PDX mouse models to evaluate the therapeutic efficacy of CS055/chiglitazar against-AML in vivo. Results: We report that the histone deacetylase inhibitor CS055, in combination with peroxisome proliferator-activated receptor (PPAR) pan-agonist (chiglitazar), synergistically targets leukemia stem-like cells from leukemia cell lines and patient samples, while sparing normal hematopoietic progenitor cells. Mechanistically, chiglitazar enhances the inhibitory effect of CS055 on HDAC3 and induces ferroptosis in LSCs-like cells by down-regulating the expression of ferroptosis suppressor SLC7A11. In fact, the inhibition of HDAC3 increases H3K27AC levels in the promoter region of activating transcription factor 3 (ATF3), a transcriptional repressor of the SLC7A11 gene, and upregulates the expression of ATF3. In contrast, ATF4, a SLC7A11 activator, is suppressed by HDAC3 inhibition. Conclusions: Our findings suggest that treatment with CS055 combined with chiglitazar, will target LSCs by inducing ferroptosis and may confer an effective approach for the treatment of AML. To investigate the molecular mechanism by which the combination of CS055 and chiglitazar inhibits LSC-like cells. For this purpose, RNA-seq analyses were performed in KG-1α cells treated with DMSO, (16 μM) chiglitazar and (4 μM) CS055 for 24 hours, respectively, all cells were collected and RNA-seq was performed by Seqhealth Technology Co., Ltd., (Wuhan, China). *************************************************************** the raw data is no longer available due to the expiration of the company's data retention period ***************************************************************