GSK-3 inhibitors induce chromosome instability.

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• Mitosis involves complex mechanisms for accurate chromosome segregation, which are often disrupted in tumor evolution, leading to chromosome instability.
• Mutations in adenomatous polyposis coli (APC) are implicated in promoting chromosome instability in colon cancer, but the underlying mechanisms are not fully understood.
• Glycogen synthase kinase 3 (GSK-3), working with APC, targets beta-catenin for degradation, prompting an investigation into its role in chromosome segregation.

Purpose of the Study:

• To investigate the role of GSK-3 in ensuring accurate chromosome segregation during mitosis.
• To determine if GSK-3 kinase activity is required for proper chromosome alignment and segregation.

Main Methods:

• Inhibition of GSK-3 kinase activity using a panel of small molecule inhibitors (SB-415286, AR-A014418, 1-Azakenpaullone, CHIR99021).
• Analysis of synchronized HeLa cells to assess effects on cell cycle progression, mitotic exit, and chromosome alignment.
• Selective repression of GSK-3beta using RNA interference to confirm findings and rule out off-target effects.

Main Results:

• GSK-3 inhibition did not prevent cell cycle progression but significantly delayed mitotic exit due to chromosome alignment defects.
• Inhibitor-treated cells frequently initiated anaphase without all chromosomes properly aligned, leading to chromosome non-disjunction.
• GSK-3beta-deficient cells exhibited similar chromosome alignment issues and accumulated micronuclei, indicating chromosome missegregation.

Conclusions:

• GSK-3 plays a critical role in accurate chromosome segregation during mitosis.
• The findings suggest that GSK-3 inhibitors, while potentially therapeutic, may induce chromosome instability as an unwanted side effect.