| OBJCTIVE: The study aimed to certain the effects of cyclooxygenase-2/5-lipoxygenase (COX-2/5-LOX) dual inhibitor darbufelone on tumor growth of human gastric adencarcinoma xenografts in nude mice, and to explore the mechanisms of proliferation, apoptosis and angiogenesis induced by darbufelone.METHODS: The xenograft models of human gastric adencarcinoma was formed in nude mice with gastric adencarcinoma cell line SGC-7901.The mice had been randomly divided into the darbufelone (45mg·kg-1·d-1)group and the control group(n=7). All the mice were given intragastric administration for 4 weeks. The growth of the subcutaneously transplanted tumor and changes in mouse body weight in each group after treatment were observed on 0, 7, 14, 21 and 28 days. The tumors were weighed for tumor growth inhibition after the animals were sacrificed. Histopathological examination of the xenograft, the liver, the kidneys, the spleen and the lungs of nude mice was also conducted. The expressions of mRNA and protein of 5-LOX, COX-2, PCNA, Bcl-2 and caspase-3 in transplantation tumor tissue were detected by RT-PCR and Immunohistochemical methods (SABC kit). The expression of CD34( representing microvessel density, MVD) was detected by immunohistochemical method (SABC kit). The expressions of mRNA and protein of VEGF and MMP-9 in transplantation tumor tissue were detected by RT-PCR and Western-blot.RESULTS: 1.Sucessfully build an subcutaneously transplanted tumor model of SGC-7901 gastric adencarcinoma cell in nude mice. 2. Tumor volume was (558.28±79.01)mm3 in darbufelone group(,1698.28±364.16)mm3 in control group(P<0.05). 3. The inhibition rate of xenografts in nude mice treated with darbufelone was 58.42%. 4. Histopathological examination results: Compared with the control group, the size of necrotic areas was found enlarged significantly in darbufelone group. However, darbufelone had no significant effects on the induction of histopathological changes in the liver,the kidneys, the spleen and the lungs of nude mice. 5. The expression of mRNA and protein of 5-LOX, COX-2, PCNA, and Bcl-2 in gastric adencarcinoma tissue of darbufelone group were markedly decreased, but the expression of caspase-3 was increased, compared with the control group (P<0.05), respectively. 6. The MVD in darbufelone group were significantly decreased compared with that in the control group (15.36±0.30 vs 29.47±0.63, P<0.05). 7. RT-PCR and Western-blot analysis showed that darbufelone effectively inhibited the expression of mRNA and protein of VEGF and MMP-9 compared with the control group(P<0.05).CONCLUSIONS: 5-lipoxygenase/cyclooxygenase-2 dual inhibitor darbufelone have obvious inhibitory effects on the tumor growth of human gastric adencarcinoma transplanted subcutaneously in nude mice. The mechanism may as follow: darbufelone inhibit the proliferation and induce apoptosis of gastric tumor cells by down regulating the expression of COX-2, 5-LOX, Bcl-2, PCNA and up regulating caspase-3.darbufelone inhibit the tumor angiogenesis, which may be achieved through inhibition of VEGF and MMP-9.
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