The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Science, Hunan Normal University, Changsha 410081, China; State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha 410081, China.
Department of Neurosurgery, Second Xiangya Hospital of Central South University, Changsha, Hunan 410008, China.
Life Sci. 2024 Nov 15;357:123111. doi: 10.1016/j.lfs.2024.123111. Epub 2024 Oct 4.
The incidence of recurrent gliomas is high, exerting low survival rates and poor prognoses. Transcription factor AP-2α has been reported to regulate the progression of primary glioblastoma (GBM). However, the function of AP-2α in recurrent gliomas is largely unclear.
The expression of AP-2α and O6-methylguanine DNA-methyltransferase (MGMT) was detected in recurrent glioma tissues and cell lines by Western blots, the regulation mechanisms between AP-2α/MGMT promoter and RA/AP-2α promoter were studied by luciferase reporter assays, EMSA, and chIP assays. The effects of AP-2α and TMZ/RA treatment on cell viability in vitro and in vivo were investigated by MTT assays, γHAX staining, comet assays and intracranial injection.
AP-2α expression negatively correlates with the expression of MGMT in glioma samples. AP-2α could directly bind with the promoter of the MGMT gene, suppresses transcriptional levels of MGMT and downregulate MGMT expression in TMZ-resistant U87MG-R and T98G cells, but TMZ treatment decreases AP-2α expression and increases MGMT expression. The extended TMZ treatment and increased TMZ concentrations reversed these effects. Moreover, AP-2α overexpression combines with TMZ to decrease cell viability, concurrently with improved DNA damage marker γHAX. Furthermore, retinoic acid (RA) activates RAR/RXR heterodimers, which bind to RA-responsive elements (RAREs) of the AP-2α promoter, and activates AP-2α expression in recurrent glioma cells. Finally, in intracranial relapsed glioma mouse model, both RA and TMZ could retard tumor development and prolong the mouse survival.
AP-2α activation by gene overexpression or RA treatment reveals the suppressive effects on glioma relapse, providing a novel therapeutic strategy against malignant refractory gliomas.
复发性神经胶质瘤的发病率较高，患者生存率低，预后差。转录因子 AP-2α 已被报道可调节原发性胶质母细胞瘤（GBM）的进展。然而，AP-2α 在复发性神经胶质瘤中的功能在很大程度上尚不清楚。
通过 Western blot 检测复发性神经胶质瘤组织和细胞系中 AP-2α 和 O6-甲基鸟嘌呤 DNA-甲基转移酶（MGMT）的表达，通过荧光素酶报告基因检测、EMSA 和 ChIP 检测研究 AP-2α/MGMT 启动子和 RA/AP-2α 启动子之间的调节机制。通过 MTT 测定、γHAX 染色、彗星试验和颅内注射研究 AP-2α 和 TMZ/RA 处理对体外和体内细胞活力的影响。
AP-2α 的表达与胶质瘤样本中 MGMT 的表达呈负相关。AP-2α 可以直接与 MGMT 基因的启动子结合，抑制 TMZ 耐药 U87MG-R 和 T98G 细胞中 MGMT 的转录水平，并下调 MGMT 表达，但 TMZ 处理会降低 AP-2α 的表达并增加 MGMT 的表达。延长 TMZ 处理和增加 TMZ 浓度会逆转这些效果。此外，AP-2α 的过表达与 TMZ 联合使用可降低细胞活力，同时改善 DNA 损伤标志物 γHAX。此外，维甲酸（RA）激活 RAR/RXR 异二聚体，其与 AP-2α 启动子中的 RA 反应元件（RARE）结合，并激活复发性神经胶质瘤细胞中的 AP-2α 表达。最后，在颅内复发性神经胶质瘤小鼠模型中，RA 和 TMZ 均可延缓肿瘤发展并延长小鼠生存期。
通过基因过表达或 RA 处理激活 AP-2α 揭示了对神经胶质瘤复发的抑制作用，为恶性难治性神经胶质瘤提供了一种新的治疗策略。
