m6A modified circPTK2 mediates TNBC chemotherapy resistance

Area of Science:

• Molecular Biology
• Oncology
• Biochemistry

Background:

• Circular RNAs (circRNAs) are emerging biomarkers for drug resistance in triple-negative breast cancer (TNBC).
• The Wnt/β-catenin pathway is implicated in TNBC chemoresistance, and its upstream regulatory mechanisms are under investigation.

Purpose of the Study:

• To investigate the upstream regulatory mechanisms of the Wnt/β-catenin pathway in TNBC chemoresistance.
• To explore the role of circPTK2 in mediating drug resistance in TNBC.
• To evaluate circPTK2 as a potential biomarker for drug resistance in TNBC.

Main Methods:

• circRNAs were screened using gene chip analysis in drug-resistant cells.
• circPTK2 expression was quantified using qRT-PCR in cells and tissues.
• Functional assays (CCK-8, Transwell, TUNEL, EdU, Western blot, immunofluorescence) assessed circPTK2's impact on TNBC cell drug sensitivity, invasion, proliferation, apoptosis, and DNA damage repair.
• Interactions between circPTK2, miR-495, and β-catenin were investigated using pull-down, dual-luciferase reporter, and RIP assays.
• A nude mouse model evaluated circPTK2's effect on cisplatin (DDP) resistance.
• m6A modification of circPTK2 was analyzed using MeRIP and RNA-EMSA.

Main Results:

• circPTK2 expression was significantly higher in drug-resistant TNBC cells and DDP-resistant tissues compared to their sensitive counterparts.
• Knockdown of circPTK2 reduced TNBC cell viability and invasion, promoted DDP-induced DNA damage, and increased sensitivity to DDP.
• circPTK2 was found to interact with miR-495, which targets β-catenin, and its stability was confirmed.
• N6-methyladenosine (m6A) modification and the m6A reader YTHDC1 were upregulated in drug-resistant cells, with YTHDC1 binding to circPTK2.

Conclusions:

• circPTK2, regulated by m6A methylation and the reader YTHDC1, plays a crucial role in mediating DDP resistance in TNBC.
• circPTK2 demonstrates potential as a non-invasive biomarker for detecting DDP resistance in TNBC patients.