Inhibition of Eg5 acts synergistically with checkpoint abrogation in promoting mitotic catastrophe

Area of Science:

• Cell biology
• Cancer research
• Molecular oncology

Background:

• The G2 DNA damage checkpoint prevents cell cycle progression after DNA damage, crucial for cancer therapy.
• Overriding this checkpoint can lead to mitotic catastrophe, but some cells survive, potentially increasing genomic instability.
• Previous work highlighted the roles of spindle assembly checkpoint and mitosis duration in mitotic catastrophe.

Purpose of the Study:

• To investigate if combining genotoxic stress, checkpoint abrogation, and Eg5 inhibition enhances mitotic catastrophe.
• To determine if this combination can sensitize cancer cells resistant to checkpoint abrogation.

Main Methods:

• Inducing DNA damage with ionizing radiation and inhibiting CHK1 with UCN-01.
• Inhibiting the mitotic kinesin Eg5 using siRNAs or monastrol.
• Assessing mitotic catastrophe and cell viability in treated cancer cells.

Main Results:

• Mitotic catastrophe induced by ionizing radiation and UCN-01 was significantly exacerbated by Eg5 inhibition.
• The combination therapy sensitized cancer cells that were resistant to checkpoint abrogation alone.
• Low concentrations of monastrol, insufficient for mitotic arrest alone, effectively promoted mitotic catastrophe when combined with DNA damage and UCN-01.

Conclusions:

• Combining genotoxic stress, G2 checkpoint abrogation, and Eg5 inhibition is a potent strategy to induce mitotic catastrophe in cancer cells.
• Sublethal concentrations of Eg5 inhibitors can be therapeutically effective when used with G2 DNA damage checkpoint abrogation.
• This combination approach offers a promising therapeutic strategy for overcoming resistance in cancer treatment.