Role of gga-miR-29b-3p in suppressing the proliferation, invasion and migration of MSB1 Marek’s disease tumor cells by the targeting of the DNMT3B gene

BACKGROUND: Marek’s disease (MD), a class II infectious, lymphoproliferative disease that mainly afflicts poultry, has been shown to cause wasting, limb paralysis, and often acute death. It is a neoplastic disease caused by a cell-binding herpesvirus that leads to the formation of tumors in various organs and tissues. Our previous reports have found that the microRNA, gga-miR-29b-3p, showed abnormal expression in MD lymphoma. However, it remains unknown whether gga-miR-29b-3p affects MD tumorigenesis. METHODS: The MD tumor cell line MSB1 was chosen to analyze the characteristics of gga-miR-29b-3p in tumors. Cell proliferation and migration were assessed by Cell Counting Kit-8 (CCK-8) and Transwell, respectively, and cell apoptosis and cycle were analyzed via fluorescent staining and flow cytometry, respectively. The regulation between gga-miR-29b-3p and its potential target genes was verified by dual luciferase results and loss-of-function assays. The effect of target genes was verified by examining the degree of RNA interference on MSB1 cells. RESULTS: Analysis revealed that gga-miR-29b-3p impaired the proliferation of the MSB1 MD tumor cell line, induced apoptosis without obvious effects on the cell cycle, and suppressed the expression of the invasion-associated MMP2 and MMP9 genes. It was concluded that DNMT3B is the direct target of gga-miR-29b-3p. As expected, the effects of DNMT3B knockdown with small interfering RNA (siRNA) on MSB1 cell proliferation, apoptosis, and cycle were associated with gga-miR-29b-3p overexpression. Moreover, BCL2 and BCL2L1 were downregulated and TNFSF10 was upregulated in both the gga-miR-29b-3p overexpression and DNMT3B knockdown groups. The expression levels of invasion-related genes were decreased post-DNMT3B knockdown. In both the gga-miR-29b-3p overexpression and DNMT3B knockdown conditions, a decrease in MEQ oncogene expression in MD virus was observed. CONCLUSIONS: Overall, gga-miR-29b-3p was demonstrated to have a suppressive effect in MD lymphoma progression via the targeting of the DNMT3B gene. Gga-miR-29b-3p overexpression and DNMT3B knockdown inhibited MSB1 cell proliferation through suppressing the pro-apoptotic gene expression and elevating the anti-apoptotic gene expression in the apoptosis pathway. Our study provides a theoretical basis for targeted treatment of MD.