ATRX Knockdown Enhances Irradiation-Induced Mitotic Catastrophe in p53-Deficient Cancer Cells

Area of Science:

• Oncology
• Cell Biology
• Genetics

Background:

• Mitotic catastrophe (MC) is a tumor suppressor mechanism crucial for genomic stability.
• Alpha-thalassemia/mental retardation syndrome X-linked (ATRX) is vital for DNA replication, repair, and maintaining mitosis.
• The impact of ATRX knockdown on radiation-induced MC is not fully understood.

Purpose of the Study:

• To investigate the effects of ATRX knockdown (KD) on irradiation-induced MC.
• To elucidate the underlying mechanisms of ATRX KD in various p53 contexts (wild-type, deficient, mutant).

Main Methods:

• Utilized p53-wild type, p53-deficient, and p53-mutant cancer cell lines.
• Administered irradiation and performed ATRX knockdown.
• Analyzed cell cycle progression, MC characteristics, and protein expression (spindle assembly checkpoint, chromosomal passenger complex).

Main Results:

• Irradiation caused G2/M arrest in all cell types.
• ATRX KD induced G1 arrest and S phase delay in irradiated HCT116 p53+/+ cells.
• ATRX KD triggered MC specifically in p53-deficient (HCT116 p53-/-) and p53-mutant (MDA-MB-231) cells, not p53-proficient cells.
• This was linked to reduced spindle assembly checkpoint and chromosomal passenger complex proteins.

Conclusions:

• ATRX KD exacerbates irradiation-induced MC in p53-deficient and mutant cancer cells.
• The mechanism involves downregulation of SAC and CPC proteins.
• This enhances radiation-induced proliferation inhibition and apoptosis in p53-deficient cells.