Objective: To explore the role of miR-29 in bladder cancer, released by exosomes into brain microglia to influence its polarization and promote angiogenesis. This, in turn, would help design therapeutic strategies for brain metastasis caused by bladder cancer.
Methods: The relative expression of miR-29 in normal bladder and bladder cancer cells was compared by qPCR technology, and the difference of specific binding between PI3K and has-miR-29a in the NC group and mimic group was verified by luciferase activity. Bladder cancer cells T24 were transfected with miR-29 NC, mimic, or neferine and divided into miR-29-NC group, miR-29-mimic group, miR-29-NC-neferine group, and miR-29-mimic-neferine group. Then they were co-cultured with microglia BV2 in a 1% hypoxia environment. The protein expressions of p-PI3K, p-AKT, p-AMPK, p-PGC-1α, p-PPARγ, CD206, and HIF1α in glial cells BV2 were detected by Western blot. The effect of each group on angiogenesis was observed by the tube formation experiment. A glioma mouse model was established, and the number of blood vessels and tumor proliferation were observed by pathological section H&E staining, to assess the effect of miR-29 on angiogenesis.
Results: qPCR and dual-luciferase reporter assay showed that miR-29 was highly expressed in bladder cancer compared with normal bladder cells. The binding of miR-29 to PI3K led to the degradation of PI3K mRNA. Protein expression analysis showed that miR-29 inhibited PI3K and p-AKT in bladder cancer cells, and promoted the expression of p-AMPK, p-PGC-1α, p-PPARγ, CD206, and HIF1α. In vivo experiments demonstrated that miR-29 could promote the cell volume of bladder cancer cells and increase the number of blood vessels in bladder cancer cells, while neferine could inhibit the above effects.
Conclusion: miR-29 can regulate PI3K/AMPK/PGC-1α/PPAR-γ signaling in microglial cells, promote their polarization to M2, and ultimately promote neovascularization in bladder cancer.