Although gene therapy was regarded as a promising approach for glioma treatment, its therapeutic efficacy was often disappointing because of the lack of efficient drug delivery systems. Mesenchymal stem cells (MSCs) have been reported to have a tropism for brain tumors and thus could be used as delivery vehicles for glioma therapy. Therefore, in this study, we attempted to treat glioma by using MSCs as a vehicle for delivering replication-competent adenovirus. We firstly compared the infectivity of type 3, type 5, and type 35 fiber-modified adenoviruses in MSCs. We also determined suitable adenovirus titer in vitro and then used this titer to analyze the ability of MSCs to deliver replication-competent adenovirus into glioma in vivo. Our results indicated that type 35 fiber-modified adenovirus showed higher infectivity than did naked type 3 or type 5 fiber-modified adenovirus. MSCs carrying replication-competent adenovirus significantly inhibited tumor growth in vivo compared with other control groups. In conclusion, MSCs are an effective vehicle that can successfully transport replication-competent adenovirus into glioma, making it a potential therapeutic strategy for treating malignant glioma.
In tumor necrosis factor (TNF) signaling, phosphorylation and activation of receptor interacting protein kinase 1 (RIPK1) by upstream kinases is an essential checkpoint in the suppression of TNF‐induced cell death. Thus, discovery of pharmacological agents targeting RIPK1 may provide new strategies for improving the therapeutic efficacy of TNF. In this study, we found that 3‐O‐acetylrubianol C (3AR‐C), an arborinane triterpenoid isolated from Rubia philippinesis, promoted TNF‐induced apoptotic and necroptotic cell death. To identify the molecular mechanism, we found that in mouse embryonic fibroblasts, 3AR‐C drastically upregulated RIPK1 kinase activity by selectively inhibiting IKKβ. Notably, 3AR‐C did not interfere with IKKα or affect the formation of the TNF receptor1 (TNFR1) complex‐I. Moreover, in human cancer cells, 3AR‐C was only sufficient to sensitize TNF‐induced cell death when c‐FLIPL expression was downregulated to facilitate the formation of TNFR1 complex‐II and necrosome. Taken together, our study identified a novel arborinane triterpenoid 3AR‐C as a potent activator of TNF‐induced cell death via inhibition of IKKβ phosphorylation and promotion of the cytotoxic potential of RIPK1, thus providing a rationale for further development of 3AR‐C as a selective IKKβ inhibitor to overcome TNF resistance in cancer therpay.
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