Studies on the proliferation inhibition effects of TUA from Actinidia chinensis Radix on lung cancer xenografts in nude mice and its preliminary mechanism

Objective: To investigate inhibitory effect of TUA (2β, 3β, 23-trihydroxy-urs-12-en-28-oic acid) isolated from Actinidia chinensis Radix on the lung cancer xenografts in nude mice and explore its preliminary mechanism. Methods: NCI-H460 cells were implanted into nude mice and the transplantation tumor block from nude mice of more than 2 generations was inoculated to the right armpits of BALB/c mice with dissecting needle to establish a lung cancer xenograft model. When the transplanted volume was about 50 mm3, the mice were randomly divided into 6 groups: (1) model group; (2) 10 mg·kg–1 cisplatin group; (3) 10 mg·kg–1 PDTC group; (4) TUA high dose group (30 mg·kg–1); (5) TUA middle dose group (12 mg·kg–1); (6) TUA low dose group (6 mg·kg–1). Administration approach was intratumoral injection. The effects of each group on the weight of transplanted tumor animals, the volume and weight of tumor were continuously observed for 14 days. Tumor volume growth curve was drawn and tumor inhibitory rate and index were calculated; HE staining was used to observe nude mice tumor tissue pathological changes. The effects of TUA on NF-κB signaling pathway related proteins were detected by immunohistochemistry and Western blot. Results: In vivo experiments showed that the transplanted tumors in nude mice became smaller compared with the models. With the increase of TUA dose, the tumor tissue became smaller and smaller, especially in high TUA dose (30 mg·kg–1). It had the similar size with the NF-κB inhibitor PDTC (10 mg·kg–1) group. HE dyeing observation results confirmed the degree of tumor necrosis and fission in TUA treated tumor tissues obviously decreased. Immunohistochemical results showed that comparing the TUA treatment group with the model group, p65 expression in tumor tissues was reduced, and expression of IκBα increased. Western blot results also showed that the NF-κB related p65 protein expression levels decreased, at the same time IκBα protein expression level increased; the apoptosis related proteins Survivin protein expression was depressed, Caspase-3 protein expression was promoted. Conclusion: TUA significantly inhibits the growth of lung transplantation tumor and its mechanism. It may be related to the decreasing the expression of p65, Survivin and increasing the expression of IκBα, Caspase-3 in tumor tissues.