Early identification of tumor metastases is beneficial to the patient's prognosis. Extended pelvic lymph node dissection (ePLND) is an effective modality for treating and controlling LNI. However, approximately 80% of patients who undergo ePLND may be overtreated and suffer from unnecessary complications, such as lymphatic leakage, lymphoedema, and thromboembolism. Timely detection and prediction of potential LNI is beneficial to maximize patient benefit. We are committed to defining different disease states by liquid biopsy, especially by detecting extracellular vesicles (EVs). EVs are particles with a lipid bilayer that are released into the extracellular space by living cells. EVs carry molecular cargo, such as proteins, nucleic acids, and lipids, playing an important role in cell communication.
We prospectively collected plasma and urine samples from which we isolated EVs. Due to its small size with 18-25 nucleotides, mircoRNA is enriched in EVs. Then we performed small RNA sequencing. We would like to highlight that we selected size exclusion chromatography (SEC) to isolate EVs which is based on molecular size. When the sample flows through the porous stationary phase, the smaller proteins and other impurities in the sample enter the pore and are not easily washed out, while the EVs with larger particle sizes in the sample do not enter the pore and flow out more quickly, thus achieving the separation of EVs. Compared with the ultracentrifugation, it harbors higher efficiency. The yield and purity are relatively high, and the gentle separation method is conducive to preserving the original morphology and biological function of EVs, which is suitable for further analysis.
Although we did not find reliable markers in plasma EV to predict LNI, we found that urinary EV-derived hsa-miR-126-3p is a potential predictor for LNI in patients with PCa. This may help select candidate patients for ePLND in clinical scenarios. In the future, we will validate its specificity and sensitivity in a large-scale cohort.
Written by: Liang Dong,1 Cong Hu1 and Kenneth J. Pienta2
- Department of Urology, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- The Brady Urological Institute, Johns Hopkins University School of Medicine, Baltimore, United States of America