Ikaros modulates cholesterol uptake: a link between tumor suppression and differentiation

Cancer Res. 2008 May 15;68(10):3715-23. doi: 10.1158/0008-5472.CAN-08-0103.

Abstract

Ikaros is a transcription factor that directs lymphoid lineage commitment and pituitary neuroendocrine cell expansion and function. Here, we show that Ikaros regulates the low-density lipoprotein receptor (LDL-R) to alter metabolism in pituitary corticotroph cells. The DNA-binding Ikaros isoform Ik1 binds and enhances activity of the LDL-R promoter. Ik1 decreases methylation and increases acetylation of histone H3 (Lys(9)) at the LDL-R promoter. Confocal microscopy and quantitative fluorometry show enhanced LDL endocytosis in Ik1-transfected cells that exhibit abundant endoplasmic reticulum, large Golgi complexes, and prominent secretory granule formation, consistent with more robust cholesterol incorporation into functionally relevant membrane-rich organelles. Consistent with these data, LDL-R(-/-) mice, like Ik(-/-) mice, have decreased circulating levels of adrenocorticotropic hormone. These findings expand the repertoire of Ikaros actions to include regulation of the cholesterol uptake metabolic pathway with therapeutic implications for lipid-modifying drugs in Ikaros-associated cancers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenocorticotropic Hormone / metabolism
  • Animals
  • Cell Differentiation
  • Cell Lineage
  • Cholesterol / metabolism*
  • Female
  • Golgi Apparatus / metabolism
  • Humans
  • Ikaros Transcription Factor / genetics
  • Ikaros Transcription Factor / physiology*
  • Male
  • Mice
  • Mice, Transgenic
  • Neoplasms / metabolism*
  • Receptors, LDL / metabolism*

Substances

  • IKZF1 protein, human
  • Receptors, LDL
  • Zfpn1a1 protein, mouse
  • Ikaros Transcription Factor
  • Adrenocorticotropic Hormone
  • Cholesterol