Novel splice-switching oligonucleotide promotes BRCA1 aberrant splicing and susceptibility to PARP inhibitor action

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• BRCA1 mutations impair DNA repair, increasing sensitivity to PARP inhibitors.
• BRCA1-functional tumors show limited sensitivity to PARP inhibitors alone.
• Targeting BRCA1-functional tumors is a key challenge in breast cancer therapy.

Purpose of the Study:

• To develop a method to sensitize BRCA1-functional tumor cells to PARP inhibitors.
• To investigate the role of BRCA1 exon 11 splicing in therapeutic response.
• To establish a novel strategy for treating BRCA1-functional breast cancers.

Main Methods:

• Designed an RNA splice-switching oligonucleotide (SSO) to induce skipping of BRCA1 exon 11.
• Transfected SSO into wild-type BRCA1 expressing cell lines.
• Assessed cell survival and DNA damage markers (γH2AX) after combined SSO and PARP inhibitor treatment.

Main Results:

• SSO transfection successfully induced BRCA1 exon 11 skipping.
• SSO treatment sensitized BRCA1-functional cells to PARP inhibitors, reducing cell survival.
• Combined SSO and PARP inhibitor treatment increased double-strand breaks (DSBs), indicating synthetic lethality.

Conclusions:

• SSO-mediated skipping of BRCA1 exon 11 is a viable strategy to enhance PARP inhibitor efficacy.
• This approach offers a potential new therapeutic avenue for BRCA1-functional breast cancer.
• The SSO method can trigger synthetic lethality in tumors with functional BRCA1.