ATG5: a distinct role in the nucleus.

Area of Science:

• Cell Biology
• Molecular Oncology
• Cancer Therapeutics

Background:

• Anticancer treatments using DNA-damaging agents activate both apoptosis and autophagy.
• The balance between these pathways determines cell fate, with autophagy potentially promoting survival.
• It is hypothesized that enhanced autophagy may impede tumor cell killing.

Purpose of the Study:

• To investigate the consequences of favoring autophagy over apoptosis during DNA-damaging anticancer treatment.
• To elucidate the underlying molecular mechanisms of cell cycle arrest and cell death induced by chemotherapy-driven autophagy.

Main Methods:

• Utilized low, sublethal doses of etoposide and cisplatin to selectively enhance autophagic flux.
• Monitored apoptosis, autophagic flux, cell cycle progression, and mitotic events over four days.
• Investigated the nuclear localization of autophagy-related protein 5 (ATG5) and its interaction with BIRC5/survivin.

Main Results:

• Low-dose etoposide and cisplatin significantly increased autophagic flux with minimal apoptosis.
• Cells exhibited G2/M cell cycle arrest, followed by mitotic catastrophe, including multipolar spindles and chromosome missegregation.
• Autophagy-related protein ATG5 was recruited to the nucleus, binding to BIRC5/survivin and disrupting the chromosome passenger complex.

Conclusions:

• Enhancing autophagy with DNA-damaging agents does not promote cell survival but rather induces mitotic catastrophe.
• Nuclear recruitment of ATG5 and its interaction with BIRC5/survivin is a key mechanism underlying chemotherapy-induced mitotic failure.
• This finding offers new insights into cancer treatment strategies targeting cell death pathways.