MIF is a 3' flap nuclease that facilitates DNA replication and promotes tumor growth

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• Cancer cells undergo rapid proliferation, leading to replication stress.
• The mechanisms by which cancer cells manage replication stress are not fully understood.

Purpose of the Study:

• To investigate the role of macrophage migration inhibitory factor (MIF) in resolving replication stress during cancer cell proliferation.
• To determine the nuclease activity of MIF and its impact on DNA synthesis and tumor growth.

Main Methods:

• Identified MIF as a 3' flap nuclease translocating to the nucleus during S phase.
• Observed co-localization of Poly(ADP-ribose) polymerase 1 and MIF at DNA replication forks.
• Assessed the effects of MIF loss and nuclease-deficient MIF mutants on cancer cell mutation frequency, cell cycle progression, and DNA synthesis.

Main Results:

• MIF nuclease activity is crucial for resolving replication stress and facilitating tumor growth.
• Loss of MIF in cancer cells resulted in increased mutation frequency, cell cycle delays, and inhibited DNA synthesis and cell growth.
• Restoring wild-type MIF rescued these phenotypes, but a nuclease-deficient mutant did not.

Conclusions:

• MIF functions as a unique 3' flap nuclease, resolving DNA flaps during replication to evade stress-induced threats.
• MIF is upregulated in breast tumors and associated with poor patient survival, suggesting its clinical relevance.
• Targeting MIF's nuclease activity could be a potential therapeutic strategy for cancer treatment.