Amplification of TLK2 Induces Genomic Instability via Impairing the G2-M Checkpoint

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Aggressive breast cancers, particularly estrogen receptor-positive (ER+) types, often exhibit chromosomal instability (CIN).
• Genomic amplifications frequently deregulate Tousled-like kinase 2 (TLK2), a cell cycle-associated kinase, in these aggressive cancers.

Purpose of the Study:

• To investigate the mechanistic role of TLK2 amplification and overexpression in the development of aggressive ER+ breast cancers.
• To explore the link between TLK2 function and chromosomal instability (CIN).

Main Methods:

• Analysis of TLK2 amplification and overexpression in aggressive breast cancer.
• Assessment of DNA damage checkpoint signaling (Chk1/2) and G2-M checkpoint function.
• Evaluation of DNA repair processes and CIN.
• Testing the sensitivity of breast cancer cells to DNA-damaging agents (irradiation, doxorubicin) upon TLK2 overexpression.

Main Results:

• TLK2 amplification and overexpression were found to impair Chk1/2-induced DNA damage checkpoint signaling.
• This impairment leads to a G2-M checkpoint defect, delayed DNA repair, and increased CIN.
• Overexpression of TLK2 modestly sensitized breast cancer cells to DNA-damaging agents.

Conclusions:

• This study establishes the first link between TLK2 function and CIN, contrasting with its paralog TLK1.
• TLK2 plays a critical role in the deregulated DNA damage pathway and increased genomic instability in aggressive ER+ breast cancers.
• Targeting TLK2 is a promising therapeutic strategy for TLK2-amplified, aggressive breast cancers.