Glioblastoma　multiforme　(GBM)　is　the　most　common　and　aggressive　brain　tumor　with　limited　therapeutic　options.　Glioma　stem　cell　(GSC)　is　thought　to　be　greatly　responsible　for　glioma　tumor　progression　and　drug　resistance.　But　the　molecular　mechanisms　of　GSC　deriving　recurrence　and　drug　resistance　are　still　unclear.　SOX9　(sex-determining　region　Y　(SRY)-box9　protein),　a　transcription　factor　expressed　in　most　solid　tumors,　is　reported　as　a　key　regulator　involved　in　maintaining　cancer　hallmarks　including　the　GSCs　state.　Previously,　we　have　observed　that　silencing　of　SOX9　suppressed　glioma　cells　proliferation　both　in　vitro　and　in　vivo.　Here,　we　found　that　SOX9　was　essential　for　GSC　self-renewal.　Silencing　of　SOX9　down-regulated　a　broad　range　of　stem　cell　markers　and　inhibited　glioma　cell　colony　and　sphere　formation.　We　identified　pyruvate　dehydrogenase　kinase　1　(PDK1)　as　a　target　gene　of　SOX9　using　microarray　analyses.　PDK1　inactivation　greatly　inhibited　glioma　cell　colony　and　sphere　formation　and　sensitized　glioma　spheres　to　temozolomide　(TMZ)　toxicity.　In　addition,　SOX9-shRNA　and　PDK1　inhibitor　could　greatly　sensitize　GSC　to　TMZ　in　vivo.　Taken　together,　our　data　reveals　that　SOX9-PDK1　axis　is　a　key　regulator　of　GSC　self-renewal　and　GSC　temozolomide　resistance.　These　findings　may　provide　help　for　future　human　GBM　therapy.