Inhibition of autophagy as a treatment strategy for p53 wild-type acute myeloid leukemia

Cell Death Dis. 2017 Jul 13;8(7):e2927. doi: 10.1038/cddis.2017.317.

Abstract

Here we have explored whether inhibition of autophagy can be used as a treatment strategy for acute myeloid leukemia (AML). Steady-state autophagy was measured in leukemic cell lines and primary human CD34+ AML cells with a large variability in basal autophagy between AMLs observed. The autophagy flux was higher in AMLs classified as poor risk, which are frequently associated with TP53 mutations (TP53mut), compared with favorable- and intermediate-risk AMLs. In addition, the higher flux was associated with a higher expression level of several autophagy genes, but was not affected by alterations in p53 expression by knocking down p53 or overexpression of wild-type p53 or p53R273H. AML CD34+ cells were more sensitive to the autophagy inhibitor hydroxychloroquine (HCQ) than normal bone marrow CD34+ cells. Similar, inhibition of autophagy by knockdown of ATG5 or ATG7 triggered apoptosis, which coincided with increased expression of p53. In contrast to wild-type p53 AML (TP53wt), HCQ treatment did not trigger a BAX and PUMA-dependent apoptotic response in AMLs harboring TP53mut. To further characterize autophagy in the leukemic stem cell-enriched cell fraction AML CD34+ cells were separated into ROSlow and ROShigh subfractions. The immature AML CD34+-enriched ROSlow cells maintained higher basal autophagy and showed reduced survival upon HCQ treatment compared with ROShigh cells. Finally, knockdown of ATG5 inhibits in vivo maintenance of AML CD34+ cells in NSG mice. These results indicate that targeting autophagy might provide new therapeutic options for treatment of AML since it affects the immature AML subfraction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD34 / metabolism
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy* / drug effects
  • Autophagy-Related Protein 5 / antagonists & inhibitors
  • Autophagy-Related Protein 5 / genetics
  • Autophagy-Related Protein 5 / metabolism
  • Autophagy-Related Protein 7 / antagonists & inhibitors
  • Autophagy-Related Protein 7 / genetics
  • Autophagy-Related Protein 7 / metabolism
  • Bone Marrow Cells / cytology
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / metabolism
  • Cell Line, Tumor
  • Female
  • Humans
  • Hydroxychloroquine / pharmacology
  • Leukemia, Myeloid, Acute / metabolism
  • Leukemia, Myeloid, Acute / pathology
  • Mice
  • Mice, Inbred NOD
  • Neoplastic Stem Cells / cytology
  • Neoplastic Stem Cells / drug effects
  • Neoplastic Stem Cells / metabolism
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA Interference
  • Reactive Oxygen Species / metabolism
  • Tumor Suppressor Protein p53 / antagonists & inhibitors
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • bcl-2-Associated X Protein / metabolism

Substances

  • Antigens, CD34
  • Apoptosis Regulatory Proteins
  • Autophagy-Related Protein 5
  • BBC3 protein, human
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • Hydroxychloroquine
  • Autophagy-Related Protein 7