Dysregulation of autophagy in chronic lymphocytic leukemia with the small-molecule Sirtuin inhibitor Tenovin-6

Sci Rep. 2013:3:1275. doi: 10.1038/srep01275.

Abstract

Tenovin-6 (Tnv-6) is a bioactive small molecule with anti-neoplastic activity. Inhibition of the Sirtuin class of protein deacetylases with activation of p53 function is associated with the pro-apoptotic effects of Tnv-6 in many tumors. Here, we demonstrate that in chronic lymphocytic leukemia (CLL) cells, Tnv-6 causes non-genotoxic cytotoxicity, without adversely affecting human clonogenic hematopoietic progenitors in vitro, or murine hematopoiesis. Mechanistically, exposure of CLL cells to Tnv-6 did not induce cellular apoptosis or p53-pathway activity. Transcriptomic profiling identified a gene program influenced by Tnv-6 that included autophagy-lysosomal pathway genes. The dysregulation of autophagy was confirmed by changes in cellular ultrastructure and increases in the autophagy-regulatory proteins LC3 (LC3-II) and p62/Sequestosome. Adding bafilomycin-A1, an autophagy inhibitor to Tnv-6 containing cultures did not cause synergistic accumulation of LC3-II, suggesting inhibition of late-stage autophagy by Tnv-6. Thus, in CLL, the cytotoxic effects of Tnv-6 result from dysregulation of protective autophagy pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Autophagy / drug effects*
  • Benzamides / toxicity*
  • Cells, Cultured
  • Gene Expression Profiling
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / drug effects
  • Humans
  • Leukemia, Lymphocytic, Chronic, B-Cell / metabolism
  • Leukemia, Lymphocytic, Chronic, B-Cell / pathology
  • Lysosomes / drug effects
  • Lysosomes / metabolism
  • Macrolides / toxicity
  • Mice
  • Microtubule-Associated Proteins / metabolism
  • Middle Aged
  • Neoplastic Stem Cells / cytology
  • Neoplastic Stem Cells / drug effects
  • Sirtuins / antagonists & inhibitors*
  • Sirtuins / metabolism
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • Benzamides
  • MAP1LC3A protein, human
  • Macrolides
  • Microtubule-Associated Proteins
  • Tumor Suppressor Protein p53
  • tenovin-6
  • bafilomycin A1
  • Sirtuins