Expression of MYBL2 and miR-631 in bladder cancer and their relationship with prognosis Huang Yu.Li Xiang.Hu Xu. "Department of Urology, Sichuan Provincial Mentol Health Center/Third Peopli's Hospital of Mianyang , Sichuan Province, Mianyang 621000 , ChinaCorresponding author: Li Xiang, E-mail: Xiang.87@ 163. comFunding program: Scientific Research Program of Sichuan Provincial Department of Education (20ZA0201)

Abstract：

Objective To investigate the expression of myeloblastoma transcription factor subtype 2(MYBL2) and microRNA-631(miR-631) in bladder cancer tissues and their relationship with the prognosis of patients.Methods 133 patients with bladder cancer who underwent surgery in the Department of Urology, West China Hospital, Sichuan University from January 2017 to May 2019 were selected as the study subjects. During the surgery, the bladder cancer tissue and normal bladder tissue adjacent to the cancer were taken. Follow-up for 3 years showed that 89 patients survived as a good prognosis group and 44 patients died as a poor prognosis group. The expression of MYBL2 mRNA and miR-631 in bladder cancer tissues and normal adjacent bladder tissues were detected by fluorescence quantitative PCR. The positive rate of MYBL2 expression in bladder cancer tissues and adjacent normal bladder tissues was detected by immunohistochemistry. Spearman method was used to analyze the correlation between MYBL2 and miR-631 in bladder cancer tissue. Kaplan Meier method was used to analyze the relationship between the expression of MYBL2, miR-631 and the prognosis of bladder cancer; Logistic regression analysis was used to analyze the risk factors of poor prognosis in bladder cancer patients.Results The proportion of patients with T3-4 stage, low differentiation and lymph node metastasis in poor prognosis group was significantly higher than that in good prognosis group(χ²/P=6.590/0.010, 14.208/<0.001, 20.828/<0.001).Compared with normal bladder tissue adjacent to cancer, the expression level of MYBL2 mRNA and the positive expression rate of MYBL2 in bladder cancer tissue were significantly higher [t/P=21.501/<0.001,χ²/P=92.371/<0.001], the expression level of miR-631 was significantly decreased(t/P=7.875/<0.001). MYBL2 and miR-631 have binding sites, and the expression of MYBL2 and miR-631 in bladder cancer tissue is negatively correlated(r/P=-0.424/<0.001). The 3-year survival rate of MYBL2 positive group is lower than that of MYBL2 negative group(χ²/P=5.052/0.025), the 3-year survival rate of miR-631 low expression group is lower than that of miR-631 high expression group(χ²/P=5.934/0.015).Logistic regression analysis showed that TNM stage T3-4, poor differentiation of tumor, lymph node metastasis, positive MYBL2 and low expression of miR-631 in bladder cancer tissue were risk factors for poor prognosis of patients [OR(95% CI)=2.153(1.453-3.191), 2.204(1.274-3.812), 2.458(1.153-5.239), 2.569(1.614-4.088), 2.941(1.798-4.810)].Conclusion MYBL2 and miR-631 are both related to the occurrence of bladder cancer, and detection of their levels is of great significance in evaluating the prognosis of bladder cancer patients.

Bladder cancer;                    MYB proto-oncogene like 2;                    MicroRNA-631;                    Prognosis;