Limited therapeutic efficacy of temozolomide (TMZ) against glioblastomas highlights the importance of exploring new drugs for clinical therapy. Sunitinib, a multitargeted receptor tyrosine kinase inhibitor, is currently being tested as therapy for glioblastomas. Unfortunately, sunitinib still has insufficient activity to cure glioblastomas. Our aim was to determine the molecular mechanisms counteracting sunitinib drug sensitivity and find potential adjuvant drugs for glioblastoma therapy. Through in vitro experiments, transcriptome screening by RNA sequencing, and in silico analyses, we found that sunitinib induced glioma apoptotic death, and downregulated genes were enriched in oncogenic genes of glioblastoma. Meanwhile, sunitinib-upregulated genes were highly associated with the protective autophagy process. Blockade of autophagy significantly enhanced sunitinib’s cytotoxicity. Growth arrest and DNA damage-inducible protein (GADD) 34 was identified as a candidate involved in sunitinib-promoted autophagy through activating p38-mitogen-activated protein kinase (MAPK) signaling. Higher GADD34 levels predicted poor survival of glioblastoma patients and induced autophagy formation in desensitizing sunitinib cytotoxicity. Guanabenz, an alpha2-selective adrenergic agonist and GADD34 functional inhibitor, was identified to enhance the efficacy of sunitinib by targeting GADD34-induced protective autophagy in glioblastoma cells, TMZ-resistant cells, hypoxic cultured cells, sphere-forming cells, and colony formation abilities. A better combined treatment effect with sunitinib and guanabenz was also observed by using xenograft mice. Taken together, the sunitinib therapy combined with guanabenz in the inhibition of GADD34-enhanced protective autophagy may provide a new therapeutic strategy for glioblastoma.

替莫唑胺（TMZ）对胶质母细胞瘤的有限治疗效果凸显了探索新药用于临床治疗的重要性。舒尼替尼是一种多靶点受体酪氨酸激酶抑制剂，目前正在测试用于治疗胶质母细胞瘤。不幸的是，舒尼替尼仍然没有足够的活性来治愈胶质母细胞瘤。我们的目的是确定抵消舒尼替尼药物敏感性的分子机制，并寻找胶质母细胞瘤治疗的潜在辅助药物。通过体外实验、RNA测序转录组筛选和计算机分析，我们发现舒尼替尼诱导胶质瘤细胞凋亡死亡，并且下调的基因在胶质母细胞瘤的致癌基因中富集。同时，舒尼替尼上调的基因与保护性自噬过程高度相关。阻断自噬显着增强舒尼替尼的细胞毒性。生长停滞和 DNA 损伤诱导蛋白 (GADD) 34 被确定为通过激活 p38 丝裂原激活蛋白激酶 (MAPK) 信号传导参与舒尼替尼促进自噬的候选蛋白。较高的 GADD34 水平预示着胶质母细胞瘤患者的生存率较差，并在舒尼替尼细胞毒性脱敏过程中诱导自噬形成。guanabenz 是一种 α2 选择性肾上腺素能激动剂和 GADD34 功能抑制剂，通过靶向 GADD34 诱导的胶质母细胞瘤细胞、TMZ 耐药细胞、缺氧培养细胞、球体形成细胞和集落形成能力中的保护性自噬，增强舒尼替尼的疗效。通过使用异种移植小鼠也观察到舒尼替尼和瓜纳苯的更好的联合治疗效果。综上所述，舒尼替尼联合胍那苯抑制GADD34增强的保护性自噬可能为胶质母细胞瘤提供新的治疗策略。