ORP4L Extracts and Presents PIP2 from Plasma Membrane for PLCβ3 Catalysis: Targeting It Eradicates Leukemia Stem Cells

Cell Rep. 2019 Feb 19;26(8):2166-2177.e9. doi: 10.1016/j.celrep.2019.01.082.

Abstract

Leukemia stem cells (LSCs) are a rare subpopulation of abnormal hematopoietic stem cells (HSCs) that propagates leukemia and are responsible for the high frequency of relapse in therapies. Detailed insights into LSCs' survival will facilitate the identification of targets for therapeutic approaches. Here, we develop an inhibitor, LYZ-81, which targets ORP4L with high affinity and specificity and selectively eradicates LCSs in vitro and in vivo. ORP4L is expressed in LSCs but not in normal HSCs and is essential for LSC bioenergetics and survival. It extracts PIP2 from the plasma membrane and presents it to PLCβ3, enabling IP3 generation and subsequent Ca2+-dependent bioenergetics. LYZ-81 binds ORP4L competitively with PIP2 and blocks PIP2 hydrolysis, resulting in defective Ca2+ signaling. The results provide evidence that LSCs can be eradicated through the inhibition of ORP4L by LYZ-81, which may serve as a starting point of drug development for the elimination of LSCs to eventually cure leukemia.

Keywords: Ca(2+) signaling; OSBP-related protein 4L; PIP(2) hydrolysis; energy metabolism; leukemia stem cell; therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Cell Line, Tumor
  • Cell Membrane / metabolism
  • Hematopoietic Stem Cells / drug effects*
  • Hematopoietic Stem Cells / metabolism
  • Humans
  • Leukemia / blood
  • Leukemia / metabolism*
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / metabolism
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Phospholipase C beta / metabolism
  • Receptors, Steroid / antagonists & inhibitors
  • Receptors, Steroid / metabolism*

Substances

  • Antineoplastic Agents
  • Phosphatidylinositol 4,5-Diphosphate
  • Receptors, Steroid
  • oxysterol binding protein
  • Phospholipase C beta