MiR-221/222 suppression induced by activation of the cAMP/PKA/CREB1 pathway is required for cAMP-induced bidirectional differentiation of glioma cells.

Factors that increase cAMP levels can induce lineage-specific differentiation of glioma cells into astrocyte-like cells. However, the differentiation pattern and underlying mechanisms remain unclear. Here, we find that cAMP/PKA/CREB1-induced miR-221/222 suppression contributes to the neuron-like differentiation of gliomas. cAMP agonists selectively induced neuron- and astrocyte-like but not oligodendrocyte-like differentiation of C6 glioma cells. PKA inhibitors and CREB1 knockout blocked neuron-like differentiation of glioma cells. cAMP inhibited miR-221/222 in a PKA/CREB1 dependent manner. Importantly, both in vitro and in vivo assays demonstrated that transcriptional suppression of miR-221/222 is required for neuronal differentiation of glioma cells. Our findings suggest that increasing cAMP levels can induce bidirectional differentiation of glioma cells. Furthermore, the miR-221/222 cluster acts as an epigenetic brake during glioma differentiation.能够升高环磷酸腺苷（cAMP）水平的因素，可诱导胶质瘤细胞发生谱系特异性分化，向星形胶质样细胞转化。然而，其分化模式与潜在分子机制仍未明确。本研究发现，cAMP/蛋白激酶A（PKA）/cAMP应答元件结合蛋白1（CREB1）通路介导的微小RNA（miR）-221/222转录抑制，可促进胶质瘤细胞向神经元样细胞分化。cAMP激动剂可选择性诱导C6胶质瘤细胞向神经元样及星形胶质样细胞分化，而非少突胶质样细胞。蛋白激酶A抑制剂与CREB1基因敲除，均可阻断胶质瘤细胞的神经元样分化过程。cAMP可通过PKA/CREB1依赖的方式抑制miR-221/222的表达。尤为重要的是，体内外实验均证实，miR-221/222的转录抑制是胶质瘤细胞发生神经元分化的必要条件。本研究结果表明，升高cAMP水平可诱导胶质瘤细胞发生双向分化。此外，miR-221/222基因簇在胶质瘤分化过程中，发挥表观遗传刹车的调控作用。