Development of a highly sensitive digital PCR assay to quantify long non-coding RNA MYU in urine samples which exhibited great potential as an alternative diagnostic biomarker for prostate cancer

Background

The diagnostic methods of prostate cancer (PCa) present major drawbacks in that serum prostate specific antigen (PSA) testing lacks specificity for PCa and prostate needle biopsy is a painful and highly invasive procedure for patients. Thus, new alternative screening methods which are specific and non-invasive both in the early detection and in the clinical definitive diagnosis of PCa are in urgent need. Long non-coding RNA MYU has been shown to promote PCa cell proliferation and migration, and is significantly upregulated both at the cellular and tumor tissue level. Therefore, long non-coding RNA MYU may be a new potential diagnostic biomarker for PCa.

Methods

In the present study, we successfully developed a highly sensitive digital PCR assay to detect long non-coding RNA in clinical urine samples. dPCR was carried out using Qx200 ddPCR EvaGreen Supermix (Bio-Rad) according to the manufacturer’s instructions.

Results

Our results indicated that the digital PCR assay showed better linearity, repeatability, and reproducibility when compared with real-time quantitative PCR. In addition, we identified the normalized MYU level and used the digital PCR assay to measure it in 100 clinical urine samples. Our study showed that the normalized MYU level is a promising diagnostic biomarker for predicting and evaluating the malignancy of PCa.

Conclusions

Our findings presented a non-invasive liquid biopsy method to detect an alternative diagnostic parameter which can assist the diagnosis of PCa in clinical practice.

Upregulation of long non-coding RNA MYU promotes proliferation, migration and invasion of esophageal squamous cell carcinoma cells

Esophageal squamous cell carcinoma (ESCC) is a common malignant tumour type of the digestive system. Long non-coding RNA (lncRNA) c-Myc upregulated (MYU), also known as VPS9 domain-containing 1 antisense 1, was recently discovered. However, the expression of lncRNA MYU in ESCC and its role in tumour progression have remained elusive. In the present study, the expression of lncRNA MYU, Ki-67 and the epithelial-mesenchymal transition-related proteins E-cadherin and Vimentin in ESCC tissues was detected by reverse transcription-quantitative PCR. The expression of Ki-67, E-cadherin and Vimentin in ESCC tissues was also detected by immunohistochemistry. A small interfering RNA plasmid was employed to establish a TE-2 cell line with knockdown on lncRNA MYU. The results indicated that the expression of lncRNA MYU was higher in ESCC tissues than in normal adjacent tissues and that upregulation of lncRNA MYU was a potential biomarker for poor prognosis. The results also suggested that the expression levels of lncRNA MYU were correlated with the histological grade, lymph node metastasis and TNM stage (P<0.05). Silencing of lncRNA MYU expression inhibited the proliferation, migration and invasion, while the expression of lncRNA MYU increased as cell proliferation increased. In addition, the mRNA expression of Vimentin and Ki-67 was decreased in TE-2 cells after lncRNA MYU was knocked down, while E-cadherin mRNA expression was elevated. In conclusion, the present results indicated that lncRNA MYU may regulate the proliferation, migration and invasion of ESCC cells, and may serve as a prognostic biomarker for ESCC.