DJ-1/PARK7 is an important mediator of hypoxia-induced cellular responses

Area of Science:

• Oncology
• Molecular Biology
• Cellular Physiology

Background:

• DJ-1 (PARK7) functions as an oncogene in cancer, promoting cell survival via Akt.
• The mechanistic basis of DJ-1's oncogenic role, particularly in tumor adaptation to hypoxia, is not fully understood.
• Hypoxia-inducible factor 1 (HIF1) is critical for tumor adaptation to hypoxia, with its stabilization partly dependent on the PI3K/Akt/mTOR pathway.

Purpose of the Study:

• To investigate the role of DJ-1 in regulating HIF1 transcriptional activity under hypoxic conditions.
• To elucidate the mechanistic link between DJ-1, Akt, mTOR, AMPK, and HIF1 stability in cancer cells.
• To determine DJ-1's contribution to cancer cell adaptation and survival during hypoxia.

Main Methods:

• Utilized human cell lines and transformed mouse fibroblasts with DJ-1 loss.
• Assessed the transcription of HIF1-responsive genes under hypoxia.
• Measured Akt, mTOR, and AMP-activated protein kinase (AMPK) activities.
• Evaluated cell survival and adaptation to hypoxic stress.

Main Results:

• Loss of DJ-1 reduced HIF1-responsive gene transcription during hypoxia.
• DJ-1 is essential for Akt and mTOR activities that maintain HIF1 stability.
• DJ-1 regulates AMPK activity, particularly under hypoxic conditions.
• DJ-1 protects cells from hypoxia-induced death and is required for adaptation to severe hypoxic stress.

Conclusions:

• DJ-1 acts as an upstream activator of HIF1 function in cancer cells.
• DJ-1's oncogenic activity is linked to enhanced cellular resistance to hypoxic stress via regulation of mTOR and AMPK.
• These findings support targeting DJ-1 for cancer therapeutics.