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Background: Arsenic trioxide has been demonstrated as an effective anti-cancer drug against leukemia and solid tumors both in vitro and in vivo. However, recent phase II trials demonstrated that single agent arsenic trioxide was poorly effective against hepatocellular carcinoma (HCC), which might be due to drug resistance. Methods: Mutation detection of p53 gene in arsenic trioxide resistant HCC cell lines was performed. The therapeutic effects of arsenic trioxide and Nutlin-3 on HCC were evaluated both in vitro and in vivo. A series of experiments including MTT, apoptosis assays, co-Immunoprecipitation, siRNA transfection, lentiviral infection, cell migration, invasion, and epithelial-mesenchy-mal transition (EMT) assays were performed to investigate the underlying mechanisms. Results: The acquisition of p53 mutation contributed to arsenic trioxide resistance and enhanced metastatic potential of HCC cells. Mutant p53 (Mutp53) silence could re-sensitize HCC resistant cells to arsenic trioxide and inhibit the metastatic activities, while mutp53 overexpression showed the opposite effects. Neither arsenic trioxide nor Nutlin-3 could exhibit obvious effects against arsenic trioxide resistant HCC cells, while combination of them showed significant effects. Nutlin-3 can not only increase the intracellular arsenicals through inhibition of p-gp but also promote the p73 activation and mutp53 degradation mediated by arsenic trioxide. In vivo experiments indicated that Nutlin-3 can potentiate the antitumor activities of arsenic trioxide in an orthotopic hepatic tumor model and inhibit the metastasis to lung. Conclusions: Acquisitions of p53 mutations contributed to the resistance of HCC to arsenic trioxide. Nutlin-3 could overcome arsenic trioxide resistance and inhibit tumor metastasis through p73 activation and promoting mutant p53 degradation mediated by arsenic trioxide.

Background: Gankyrin has shown to be overexpressed in human liver cancers and plays a complex role in hepatocarcinogenesis. Panobinostat (LBH589), a new hydroxamic acid-derived histone deacetylase inhibitor has shown promising anticancer effects recently. Here, we investigated the potential of LBH589 as a form of treatment for hepatocellular carcinoma (HCC). Methods: Gankyrin plasmid was transfected into HCC cells, and the cells were selected for more than 4 weeks by incubation with G418 for overexpression clones. The therapeutic effects of LBH589 were evaluated in vitro and in vivo. Cell proliferation, apoptosis, cell cycle, invasive potential, and epithelial-mesenchy-mal transition (EMT) were examined. Results: LBH589 significantly inhibited HCC growth and metastasis in vitro and in vivo. Western blotting analysis indicated that LBH589 could decrease the expression of gankyrin and subsequently reduced serine-phosphorylated Akt and tyrosine-phosphorylated STAT3 expression although the total Akt and STAT3 were unaffected. LBH589 inhibited metastasis in vitro via down-regulation of N-cadherin, vimentin, TWIST1, VEGF and up-regulation of E-cadherin. LBH589 also induced apoptosis and G1 phase arrest in HCC cell lines. Ectopic expression of gankyrin attenuated the effects of LBH589, which indicates that gankyrin might play an important role in LBH589 mediated anticancer effects. Lastly, in vivo study indicated that LBH589 inhibited tumor growth and metastasis, without discernable adverse effects comparing to control group, with abrogating gankyrin/STAT3/Akt pathway. Conclusions: Our results suggested that LBH589 could inhibit HCC growth and metastasis through down-regulating gankyrin/STAT3/Akt pathway. LBH589 may present itself as a novel therapeutic strategy for HCC.

Background: Interleukin 6 (IL-6)-mediated signal transducers and activators of transcription 3 (STAT-3) phosphorylation (activation) is aberrantly sustained in cholangiocarcinoma cells resulting in enhanced myeloid cell leukemia 1 (Mcl-1) expression and resistance to apoptosis. FTY720, a new immunosuppressant, derived from ISP-1, has been studied for its putative anti-cancer properties. This study aimed to elucidate the mechanism by which FTY720 mediates antitumor effects in cholangiocarcinoma (CC) cells.Methods: Three CC cell lines were examined, QBC939, TFK-1, and HuCCT1. The therapeutic effects of FTY720 were evaluated in vitro and in vivo. Cell proliferation, apoptosis, cell cycle, invasive potential, and epithelial- mesenchy-mal transition (EMT) were examined.Results: FTY720 greatly inhibited CC cells proliferation and EMT in vitro and in vivo, and this effect was associated with dephosphorylation of STAT3tyr705. FTY720 induced apoptosis and G1 phase arrest in CC cells, and inhibited invasion of CC cells. Western blot analysis showed that FTY720 induced cleavage of caspases 3, 8 and 9, and of PARP, in a dose-dependent manner, consistent with a substantial decrease in p-STAT3, Bcl-xL, Bcl-2, survivin, cyclin D1, cyclin E, N-cadherin, vimentin, VEGF and TWIST1. In vivo studies showed that tumor growth and metastasis were significantly suppressed after FTY720 treatment.Conclusions: These results suggest that FTY720 induces a significant decrease in p-STAT3, which inhibits proliferation and EMT of CC cells, and then induces G1 phase arrest and apoptosis. We have characterized a novel immunosuppressant, which shows potential anti-tumor effects on CC via p-STAT3 inhibition. FTY720 merits further investigation and warrants clinical evaluation. [ABSTRACT FROM AUTHOR]

Developmentally regulated endothelial cell locus-1 (Del1) is an embryonic angiogenic factor expressed in early embryonic endothelial cells, but recently has been found to be expressed in some forms of cancers including colon and breast cancers, and melanoma, and human cancer cell lines. Overexpression of Del1 accelerates tumor growth by enhancing vascular formation, implying Del1 may be a potential target for anti-angiogenic cancer therapy. The study aims to investigate whether downregulation of Del1 could inhibit the growth of tumors established in nude Balb/c mice by subcutaneous implantation of human LS-174T colon cancer cells. The shRNA expression vectors targeting human Del1, and vascular endothelial growth factor (VEGF) were constructed. Gene transfection of Del1-shRNA downregulated expression of Del1 in LS-174T cells in vivo and in vitro, but did not alter the proliferative or survival properties of cells in vitro. Gene transfection of VEGF-shRNA downregulated expression of both VEGF and Del1 in LS-174T cells in vivo and in vitro. Both Del1-shRNA and VEGF-shRNA gene therapies exhibited anti-tumor activities and they also showed a synergistic effect in suppressing growth of colon tumors by anti-angiogenesis and anti-proliferation. Although further investigation to clarify the mechanisms explaining the role of Del1 in tumor growth, and the interaction between VEGF and Del1, is required, the results indicate that downregulation of Del1 presents a potent therapeutic strategy to combat colon cancer.

Chemotherapy combined with antiangiogenic therapy is more effective than chemotherapy alone. The aim of this study was to investigate whether endostatin, a potent anti-angiogenic agent, could enhance the efficacy of paclitaxel to combat breast cancer. An expression plasmid encoding mouse endostatin (End-pcDNA3.1) was constructed, which produced intense expression of endostatin and inhibited angiogenesis in the chorioallantoic membrane assay. 4T1 breast tumors were established in BALB/c mice by subcutaneous injection of 1 x 10(5) 4T1 cells. The End-pcDNA3.1 plasmid diluted in the transfection reagent FuGENE was injected into the tumors (around 100 mm(2)), and paclitaxel was injected i.p. into the mice. Endostatin gene therapy synergized with paclitaxel in suppressing the growth of 4T1 tumors and their metastasis to the lung and liver. Both endostatin and paclitaxel inhibited tumor angiogenesis and induced cell apoptosis. Despite the finding that endostatin was superior to paclitaxel at inhibiting tumor angiogenesis, paclitaxel was nevertheless more effective at inducing tumor apoptosis. The combination of paclitaxel and endostatin was more effective in suppressing tumor growth, metastases, angiogenesis, and inducing apoptosis than the respective monotherapies. The combinational therapy with endostatin and paclitaxel warrants future investigation as a therapeutic strategy to combat breast cancer.