RESUMO
Bladder carcinoma (BC) is the tenth most frequent malignancy worldwide, with high morbidity and mortality rates. Despite recent treatment advances, high-grade BC and muscle-invasive BC present with significant progression and recurrence rates, urging the need for alternative treatments. The microRNA-21 (miR-21) has superexpression in many malignancies and is associated with cellular invasion and progression. One of its mechanisms of action is the regulation of RECK, a tumor suppressor gene responsible for inhibiting metalloproteinases, including MMP9. In a high-grade urothelial cancer cell line, we aimed to assess if miR-21 downregulation would promote RECK expression and decrease MMP9 expression. We also evaluated cellular migration and proliferation potential by inhibition of this pathway. In a T24 cell line, we inhibited miR-21 expression by transfection of a specific microRNA inhibitor (anti-miR-21). There were also control and scramble groups, the last with a negative microRNA transfected. After the procedure, we performed a genetic expression analysis of miR-21, RECK, and MMP9 through qPCR. Migration, proliferation, and protein expression were evaluated via wound healing assay, colony formation assay, flow cytometry, and immunofluorescence.After anti-miR-21 transfection, miR-21 expression decreased with RECK upregulation and MMP9 downregulation. The immunofluorescence assay showed a significant increase in RECK protein expression (p < 0.0001) and a decrease in MMP9 protein expression (p = 0.0101). The anti-miR-21 transfection significantly reduced cellular migration in the wound healing assay (p < 0.0001). Furthermore, in the colony formation assay, the anti-miR-21 group demonstrated reduced cellular proliferation (p = 0.0008), also revealed in the cell cycle analysis by flow cytometry (p = 0.0038). Our results corroborate the hypothesis that miR-21 is associated with BC cellular migration and proliferation, revealing its potential as a new effective treatment for this pathology.
RESUMO
BACKGROUND: Bladder cancer is the leading transitional cell carcinoma affecting men and women with high morbidity and mortality rates, justifying the need to develop new molecular target therapies using microRNAs. This study aimed to evaluate the behavior of the T24 cell line after transfection with miR-Let-7c precursor mimic through invasion, migration, apoptosis, and cell cycle assays. METHODS AND RESULTS: T24 cell was transfected with the Let-7c mimic and its respective control and evaluated after 24 h. The expression levels of miR-Let-7c were analyzed by qPCR. We performed wound healing, Matrigel and flow cytometry, apoptosis, and cell cycle assays to determine its effect on cellular processes. Cells transfected with miR-Let-7c showed increased apoptosis rates (p = 0.019), decreased migration 24 h (p = 0.031) and 48 h (p = 0.0006), invasion potential (p = 0.0007), and cell proliferation (p = 0.002). CONCLUSIONS: Our results demonstrate that miR-Let-7c can act in different pathways of the carcinogenic cellular processes of muscle-invasive urothelial carcinoma cells, inhibiting cell proliferation and increasing apoptosis levels, consequently limiting their invasion potential. However, further studies should be carried out better to elucidate this microRNA's role in high-grade urothelial carcinomas and unveil which targets this microRNA may present, which are intrinsically related to the cancer survival pathways.
