sp2509 and Leukemia--Myeloid--Acute

Acute myeloid leukemia (AML) is a hematological malignancy with rapid disease progression and often becomes lethal without treatment. Development of effective new therapies is essential to improve the clinical outcome of AML patients. Enhancer of zeste homolog 2 (EZH2) and lysine specific demethylase 1 (LSD1) play important roles in epigenetic regulation and their altered expressions have been observed in cancer. Although EZH2 and LSD1 have opposite histone methylation functions, we found that both enzymes were paradoxically up-regulated in AML cells. Importantly, a combined inhibition of EZH2 and LSD1 resulted in a synergistic activity against AML in vitro and in vivo. Such synergy was mechanistically correlated with up-regulation of H3K4me1/2 and H3K9Ac and down-regulation of H3K27me3, leading to a decrease of anti-apoptotic protein Bcl-2. These epigenetic alterations also compromised the mitochondrial respiration capacity and glycolytic activity and resulted in ATP depletion, a key event contributing to the potent cytotoxic effect of the drug combination. Taken together, our work identified a novel therapeutic approach against AML by combining two small molecules that inhibit different histone methylation-modulating proteins with apparently opposite enzyme activities. Such a new drug combination strategy likely has significant clinical implications since epigenetic modulators are currently in clinical trials.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzamides; Biphenyl Compounds; Dose-Response Relationship, Drug; Drug Synergism; Energy Metabolism; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Epigenesis, Genetic; Female; Histone Demethylases; Histones; HL-60 Cells; Humans; Hydrazines; Leukemia, Myeloid, Acute; Methylation; Mice, Inbred BALB C; Mice, Nude; Mitochondria; Morpholines; Proto-Oncogene Proteins c-bcl-2; Pyridones; Sulfonamides; Time Factors; Tumor Cells, Cultured; Up-Regulation; Xenograft Model Antitumor Assays

Topics: Animals; Histone Demethylases; Humans; Hydrazines; Leukemia, Myeloid, Acute; Mice; Neoplasm Proteins; Sulfonamides; THP-1 Cells; Xenograft Model Antitumor Assays

The histone demethylase LSD1 (KDM1A) demethylates mono- and di-methylated (Me2) lysine (K) 4 on histone H3. High LSD1 expression blocks differentiation and confers a poor prognosis in acute myeloid leukemia (AML). Here, treatment with the novel LSD1 antagonist SP2509 attenuated the binding of LSD1 with the corepressor CoREST, increased the permissive H3K4Me3 mark on the target gene promoters, and increased the levels of p21, p27 and CCAAT/enhancer binding protein α in cultured AML cells. In addition, SP2509 treatment or LSD1 shRNA inhibited the colony growth of AML cells. SP2509 also induced morphological features of differentiation in the cultured and primary AML blasts. SP2509 induced more apoptosis of AML cells expressing mutant NPM1 than mixed-lineage leukemia fusion oncoproteins. Treatment with SP2509 alone significantly improved the survival of immune-depleted mice following tail-vein infusion and engraftment of cultured or primary human AML cells. Co-treatment with pan-HDAC inhibitor (HDI) panobinostat (PS) and SP2509 was synergistically lethal against cultured and primary AML blasts. Compared with each agent alone, co-treatment with SP2509 and PS significantly improved the survival of the mice engrafted with the human AML cells, without exhibiting any toxicity. Collectively, these findings show that the combination of LSD1 antagonist and pan-HDI is a promising therapy warranting further testing against AML.

Topics: Animals; Apoptosis; Cells, Cultured; Co-Repressor Proteins; Disease Models, Animal; Enzyme Inhibitors; Female; Histone Acetyltransferases; Histone Demethylases; Histones; Humans; Hydrazines; Leukemia, Myeloid, Acute; Mice, Inbred NOD; Mice, SCID; Nerve Tissue Proteins; Nucleophosmin; RNA, Small Interfering; Stem Cells; Sulfonamides; Tumor Cells, Cultured; Xenograft Model Antitumor Assays