Absolute Quantification of circNF1 in ESCC

Using Droplet Digital PCR
Publication Highlight

Wang, C., Ju, C., Du, D., Zhu, P., et al. (2025). CircNF1 modulates the progression and immune evasion of esophageal squamous cell carcinoma through dual regulation of PD-L1 (1)


1 | The Challenge in Quantifying circRNAs

Circular RNAs like circNF1 are highly stable and present in low abundance, especially in serum samples. Standard qPCR lacks the sensitivity and precision needed to measure their absolute copy numbers reliably in clinical specimens.

2 | Why Absolute Quantification Matters

Absolute quantification enables researchers to directly compare circNF1 levels across samples—critical for:

  • Correlating expression with PD-L1 levels
  • Assessing CD8⁺ T-cell infiltration
  • Monitoring response to immunotherapy

Unlike qPCR, digital PCR (ddPCR) partitions reactions into thousands of droplets and provides copy numbers per microliter without needing a standard curve (2).

3 | Sniper DQ24 in Action

The Sniper DQ24 ddPCR system (Sniper Medical Technology) was deployed for:

  • Tumor tissue and serum assays targeting circNF1 via back-splice junction–spanning primers
  • Droplet partitioning, thermal cycling, and endpoint detection within a single integrated platform
  • Precise calculation of absolute circNF1 copies per microliter of sample


4 | Scientific Impact

Using Sniper DQ24, Wang et al. demonstrated:

  • Elevated circNF1 levels in ESCC tissues and patient serum
  • Positive correlation with PD-L1 expression, implying immune evasion
  • Inversely correlated CD8⁺ T-cell presence
  • Declining circNF1 in serum of patients responding to PD-L1 blockade

These insights underline circNF1’s dual role as a biomarker and a driver of disease progression.

5 | Why Sniper DQ24 Stands Out
  • Monodisperse droplets via VibroJect™, ensuring accurate quantification
  • All-in-one workflow: sample loading to data analysis, with no extra steps
  • Copy number precision, ideal for low-abundance targets in body fluids
  • Strong alignment with clinical research needs for reproducibility and sensitivity (3)

6 | References
  1. Wang, C., Ju, C., Du, D., Zhu, P., et al. (2025). CircNF1 modulates the progression and immune evasion of esophageal squamous cell carcinoma through dual regulation of PD-L1. Cellular & Molecular Biology Letters, 30, 37.
  2. Hindson, C. M., et al. (2013). Absolute quantification by droplet digital PCR versus analog real-time PCR. Nature Methods, 10, 1003–1005.
  3. Sniper DQ24 Gene Expression Analysis. Sniper Medical Technology Co., Ltd.


7 | Learn More

Sniper DQ24 Digital PCR System: Explore on Darwin Science
Gene Expression Analysis with DQ24: How it enables absolute quantification

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