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Mieap-regulated mitochondrial quality control is frequently inactivated in human colorectal cancer

H Kamino1, Y Nakamura1, M Tsuneki1

  • 1Division of Cancer Biology, National Cancer Center Research Institute, Tokyo, Japan.

Oncogenesis
|January 5, 2016
PubMed

Insights

Mitochondrial quality control, regulated by Mieap (Mitochondria-associated protein), is crucial for suppressing colorectal cancer. Its inactivation, due to p53/Mieap/BNIP3 pathway dysfunction, promotes cancer cell migration and invasion in hypoxic environments.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Mitochondrial Biology

Background:

  • Mitochondrial quality control is essential for cellular health and preventing diseases like cancer.
  • Mieap (p53-inducible protein) plays a key role in mitochondrial homeostasis by managing mitochondrial repair and elimination.
  • BNIP3 and NIX are identified as crucial mediators in the Mieap-regulated mitochondrial quality control pathway.

Purpose of the Study:

  • To investigate the role and inactivation mechanisms of the Mieap-regulated mitochondrial quality control pathway in human colorectal cancer.
  • To determine the frequency of p53, Mieap, BNIP3, and NIX alterations in colorectal cancer tissues.
  • To understand how hypoxia influences this pathway and its impact on colorectal cancer progression.

Main Methods:

  • Analysis of p53, Mieap, BNIP3, and NIX status, including promoter methylation and p53 mutation, in 57 primary colorectal cancer tissues.
  • Experimental manipulation (knockdown) of p53, Mieap, and BNIP3 in LS174T colorectal cancer cells.
  • Assessment of mitochondrial quality, reactive oxygen species (ROS) generation, and cancer cell migration/invasion under hypoxic conditions.

Main Results:

  • The p53/Mieap/BNIP3-regulated mitochondrial quality control pathway is inactivated in over 70% of colorectal cancer patients, primarily through Mieap/BNIP3 promoter methylation and p53 mutations.
  • Hypoxia activates Mieap-mediated mitochondrial quality control in colorectal cancer cells.
  • Deficiency in the p53/Mieap/BNIP3 pathway under hypoxia leads to accumulation of unhealthy mitochondria, increased mitochondrial ROS, and enhanced cancer cell migration and invasion.

Conclusions:

  • The Mieap-regulated mitochondrial quality control pathway is a significant tumor suppressor in colorectal cancer.
  • Inactivation of this pathway, particularly in the hypoxic tumor microenvironment, contributes to colorectal cancer progression.
  • Targeting mitochondrial quality control mechanisms presents a potential therapeutic strategy for colorectal cancer.

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