Witham Timothy F, Erff Melanie L, Okada Hideho, Chambers William H, Pollack Ian F
Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pennsylvania, USA.
Neurosurgery. 2002 Jun;50(6):1327-34; discussion 1334-5. doi: 10.1097/00006123-200206000-00025.
On the basis of recent studies indicating that tumoral apoptotic bodies may provide a potent source of antigen for delivery to antigen-presenting cells, as well as observations that signal transduction modulation may constitute a promising approach for inducing glioma cell apoptosis, we explored the efficacy of vaccination with glioma apoptotic body-pulsed dendritic cells (DCs) for inhibiting tumor growth in the syngeneic 9L glioma/Fischer rat model.
For induction of apoptosis, 7-hydroxystaurosporine (UCN-01) (200-300 ng/ml), a selective protein kinase C inhibitor, was co-incubated with 9L cells in vitro for 72 or 96 hours. After this pretreatment period, glioma cells and DCs were mixed, and the interaction between DCs and apoptotic 9L tumor cells was assessed using two-color flow cytometry. In a series of experiments, the efficacy of vaccination strategies using DCs co-cultured with apoptotic 9L cells was then examined in animals harboring intracranial tumors.
Pretreatment of 9L cells with UCN-01 resulted in approximately 50% of cells' being observed to undergo apoptosis as compared with less than 3% of controls. After subsequent co-culture, two-color flow cytometry demonstrated a time-dependent physical association of DCs with the apoptotic glioma cells. Survival in animals harboring intracranial tumors was significantly longer for the animals treated with a glioma apoptotic body-pulsed DC vaccine than in the animals that received apoptotic glioma cells and DCs alone or vehicle (i.e., the controls), especially those that underwent a sequential vaccination strategy (P < 0.0001). Long-term survival (>90 d) was demonstrated in 6 (75%) of 8 animals that underwent this vaccination approach versus 0 (0%) of 16 controls. In contrast, no survival benefit was observed in animals that received DCs that were co-cultured with vehicle-treated (non-apoptotic) 9L cells. Three of four long-term survivors that were rechallenged intracranially with tumor cells also survived over the long term.
These studies suggest that induction of apoptosis in glioma cells by use of UCN-01 may promote the uptake of tumor antigens by DCs. This finding is important because apoptotic body-stimulated DCs may hold promise in promoting a host response against an established intracranial glioma, particularly if the parameters for apoptotic induction, duration of co-culture, and vaccination can be optimized.
基于近期研究表明肿瘤凋亡小体可能为递送至抗原呈递细胞提供强大的抗原来源，以及信号转导调节可能是诱导胶质瘤细胞凋亡的一种有前景的方法，我们探讨了用胶质瘤凋亡小体负载的树突状细胞（DCs）接种疫苗在同基因9L胶质瘤/Fischer大鼠模型中抑制肿瘤生长的疗效。
为诱导凋亡，将选择性蛋白激酶C抑制剂7-羟基星状孢菌素（UCN-01）（200 - 300 ng/ml）与9L细胞在体外共孵育72或96小时。在此预处理期后，将胶质瘤细胞和DCs混合，并用双色流式细胞术评估DCs与凋亡的9L肿瘤细胞之间的相互作用。在一系列实验中，然后在患有颅内肿瘤的动物中检查使用与凋亡的9L细胞共培养的DCs的接种疫苗策略的疗效。
用UCN-01预处理9L细胞后，观察到约50%的细胞发生凋亡，而对照组不到3%。随后共培养后，双色流式细胞术显示DCs与凋亡的胶质瘤细胞存在时间依赖性的物理关联。与单独接受凋亡的胶质瘤细胞和DCs或载体（即对照组）的动物相比，用胶质瘤凋亡小体负载的DC疫苗治疗的患有颅内肿瘤的动物的生存期明显更长，尤其是那些采用序贯接种策略的动物（P < 0.0001）。采用这种接种方法的8只动物中有6只（75%）实现了长期存活（>90天），而16只对照组动物中无一例（0%）存活。相比之下，接受与用载体处理（非凋亡）的9L细胞共培养的DCs的动物未观察到生存获益。四只长期存活者中有三只在颅内再次接种肿瘤细胞后也长期存活。
这些研究表明，使用UCN-01诱导胶质瘤细胞凋亡可能促进DCs摄取肿瘤抗原。这一发现很重要，因为凋亡小体刺激的DCs在促进宿主对已建立的颅内胶质瘤的反应方面可能具有前景，特别是如果凋亡诱导参数、共培养持续时间和接种疫苗方法能够优化的话。
