Telomeric allelic imbalance indicates defective DNA repair and sensitivity to DNA-damaging agents

Area of Science:

• Genomics
• Cancer Biology
• Molecular Oncology

Background:

• DNA repair competency influences sensitivity to chemotherapy drugs like cisplatin.
• Cancer cells with intact DNA repair can evade genome damage accumulation and repair platinum-induced DNA damage.

Purpose of the Study:

• To identify genomic signatures of defective DNA repair.
• To correlate these signatures with platinum chemotherapy sensitivity in cell lines and tumors.

Main Methods:

• Assessed the number of subchromosomal regions with allelic imbalance extending to the telomere (N(tAI)).
• Correlated N(tAI) with cisplatin sensitivity in vitro.
• Evaluated N(tAI) against pathologic response to preoperative cisplatin in triple-negative breast cancer (TNBC) and serous ovarian cancer patients.

Main Results:

• N(tAI) predicted cisplatin sensitivity in vitro.
• Higher N(tAI) levels correlated with better pathologic response to cisplatin in TNBC patients.
• Higher N(tAI) levels predicted better initial response in serous ovarian cancer patients treated with platinum chemotherapy.
• Found an inverse relationship between BRCA1 expression and N(tAI) in sporadic TNBC and serous ovarian cancers without BRCA1/BRCA2 mutations.

Conclusions:

• Accumulation of telomeric allelic imbalance (N(tAI)) serves as a marker for platinum sensitivity, suggesting impaired DNA repair.
• N(tAI) may identify cancer patients, including those without BRCA mutations, who are likely to benefit from DNA repair-targeting treatments.