RSL3 triggers glioma stem cell differentiation via the Tgm2/AKT/ID1 signaling axis.

ABSTRACT

RSL3 is a synthetic molecule that inactivates glutathione peroxidase 4 to induce ferroptosis. However, its effect on glioma stem cells (GSC) remains unclear. In this study, we found that RSL3 significantly suppressed GSC proliferation and induced their differentiation into astrocytes, which was accompanied by the downregulation of stemness-related markers, including Nestin and Sox2. Combined transcriptome and proteome analyses further revealed that RSL3 promoted GSC differentiation by suppressing transglutaminase 2 (Tgm2), but not by ferroptosis-related pathways. Tgm2 overexpression in CSC2078 cells rescued the changes in stemness-related markers and differentiation caused by RSL3, which was mediated by inhibitor of DNA binding 1 (ID1) activation. Further studies identified ID1 as a downstream signaling target of Tgm2. Blocking the phosphoinositide-3 kinase (PI3K)/Akt pathway with LY294002 suppressed PI3K, p-Akt, and ID1 levels but not Tgm2. Tgm2 overexpression abrogated the changes in PI3K, p-Akt, and ID1 levels caused by LY294002. Taken together, we demonstrate that RSL3 does not induce ferroptosis; instead, it inhibits GSC proliferation and triggers their differentiation by suppressing the Tgm2/Akt/ID1 signaling axis.