Gliomas display cellular hierarchies with self-renewing tumorigenic glioma stem cells (GSCs) at the apex. The GSC niches function as a regulator of GSC maintenance, however, the exact components of GSC niches that mediate this process are still far from fully defined. Here, we showed that glioma cells with aberrant mesenchymal phenotypes constitute a mesenchymal niche for GSCs. Using patient-derived specimens, we demonstrated that the paracrine PGI signaling, initiated by mesenchymal glioma cells, induces the self-renewal and tumorigenic potentials of GSCs through induction of KLF4. Treatment of intracranial orthotopic xenografts with shPGI or shKLF4 leads to less lethal potency. Our data therefore suggest that blockade of the PGI-KLF4 pathway may provide a therapeutic strategy against GSC niches.
Evodiamine, a quinolone alkaloid, is one of the major bioactive compounds of Evodia rutaecarpa Bentham (Rutaceae). It exhibits excellent biological activities, especially the anticancer activity. This study aims to investigate the effect of evodiamine on the proliferation of leukemia cell line K562 and to explore the underlying mechanism. The effect of evodiamine on K562 cells proliferation was analyzed by trypan blue dye exclusion assay and MTT assay. The expression levels of peroxisome proliferators-activated receptor gamma (PPARγ), cyclin D1, and p21 were detected by western blot assay. The results demonstrated that evodiamine inhibited the proliferation and decreased the viability of K562 cells in a dose- and time-dependent manner. 2-Chloro-5-nitro-N-phenylbenzamide (GW9662) and/or PPARγ-siRNA pretreatment alleviated the cell growth suppression triggered by evodiamine. Meanwhile, evodiamine intervention elevated the expression of PPARγ in K562 cells, while pretreatment with GW9662 attenuated the enhanced upregulation of PPARγ expression induced by evodiamine. In addition, GW9662 and PPARγ-siRNA pretreatment also significantly attenuated the downregulation of the cell cycle control protein cyclin D1 and the upregulation of cyclin-dependent kinase inhibitor p21 induced by evodiamine. In conclusion, PPARγ signaling pathway may involve in the proliferation inhibition of evodiamine on K562 cells via inhibiting cylcin D1 and stimulating of p21.
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