Objective: To investigate the correlations of the methylation statuses of miR-200b in tissue and serum of bladder cancer(BLCA) patients with epithelial-mesenchymal transition(EMT) and clinical pathological features. Methods: From September 2018 to October 2020, the tumor tissue samples and blood samples of 126 BLCA patients who underwent surgery(BLCA group) in our hospital were collected. And 63 samples of normal bladder mucosa tissues were selected as the control group. The methylation statuses of miR-200b in tissue and serum samples were detected by methylation-specific PCR. Quantitative real-time fluorescent PCR was used to detect the expressions of serum miR-200b. Based on The Cancer Genome Atlas(TCGA) database, the relationship between miR-200b in tissues of BLCA patients and EMT related transcription factors was analyzed. Results: The methylation rate of miR-200b in BLCA group was higher than that in the control group(P<0.05), and the expression of miR-200b was lower than that in the control group(P<0.05). For BLCA patients, the results of miR-200b methylation statuses in tumor tissue and serum samples were consistent(Kappa=0.715, P<0.001), and the expression level of serum miR-200b in serum miR-200b methylation subgroup was significantly lower than that in unmethylation subgroup(P<0.05). The patients with muscle-invasive, distant metastasis or middle-low grade bladder cancer had higher methylation rates of tissue and serum miR-200b, and the patients with lymph node metastasis also had higher methylation rates of serum miR-200b(P<0.05). Based on TCGA database, the expressions of miR-200b were negatively correlated with the expression of hyaluronan synthases-2, zinc finger E-box-binding homeobox(ZEB) 1 and ZEB2 proteins expressions in BLCA patients(P<0.05). Conclusion: The methylation statuses of miR-200b are common in tissue and serum samples of BLCA patients, which are related to the muscle-invasion, distant metastasis and the degree of differentiation. Its mechanism may be through up-regulating the expression of EMT related transcription factors, thus activating the EMT process.
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