NSUN2-mediated R-loop stabilization as a key driver of bladder cancer progression and cisplatin sensitivity

Area of Science:

• Molecular Biology
• Cancer Research
• Epigenetics

Background:

• R-loops are crucial for genomic stability and gene expression regulation.
• Dysregulation of R-loops is implicated in various cancers, including bladder cancer (BCa).
• The role of 5-methylcytosine (m⁵C) methyltransferase NSUN2 in R-loop dynamics and BCa remains unclear.

Purpose of the Study:

• To investigate the interaction between NSUN2 and R-loops in bladder cancer cells.
• To elucidate the role of NSUN2 in transcriptional regulation and DNA damage repair in BCa.
• To identify potential therapeutic targets for bladder cancer treatment.

Main Methods:

• Analysis of R-loop levels in BCa cells versus normal urothelial cells.
• Investigation of NSUN2's interaction with R-loops and its catalytic activity dependence.
• Assessment of NSUN2's recruitment of EZH2 to the PRDM11 gene promoter.
• Evaluation of NSUN2 knockdown effects on tumor growth, DNA damage, and homologous recombination repair in response to cisplatin.

Main Results:

• Elevated R-loop levels were observed in BCa cells compared to normal cells.
• NSUN2 binds and stabilizes R-loops via its m⁵C catalytic activity.
• NSUN2 recruits EZH2 to epigenetically silence the tumor suppressor PRDM11, promoting BCa progression.
• NSUN2 knockdown sensitizes BCa to cisplatin, reduces tumor growth, increases DNA damage, and impairs MRE11 recruitment, hindering homologous recombination repair.

Conclusions:

• NSUN2 is a key regulator of R-loops in bladder cancer, contributing to tumorigenesis through epigenetic silencing of PRDM11.
• NSUN2 plays a critical role in DNA damage repair, specifically homologous recombination.
• Targeting NSUN2 presents a promising therapeutic strategy for bladder cancer, potentially enhancing sensitivity to chemotherapy like cisplatin.