The epigallocatechin gallate derivative Y6 inhibits human hepatocellular carcinoma by inhibiting angiogenesis in MAPK/ERK1/2 and PI3K/AKT/ HIF-1α/VEGF dependent pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Hypervascularity has been considered as one of the major features of many solid tumors. Green tea is one of the commonly drink resources in China, and its active component, Epigallocatechin gallate (EGCG), exhibits antiangiogenic activities in various experimental tumor models. However, EGCG has many shortages, e.g., relatively unstable, low lipid solubility, poor bioavailability, and short duration of action. AIM OF THE STUDY: To overcome the shortages of EGCG for antiangiogenic antitumor usage, our study developed a novel EGCG derivate, Y6(5,3',4',3″,4″,5″-6-0-ethyl-EGCG). The underlying mechanism was also elucidated. MATERIAL AND METHODS: we evaluated the effects of EGCG, Y6 on HCC and angiogenesis in vivo and in vitro. Moreover, to understand their antitumor mechanisms, key factors within angiogenesis-related signaling pathways (MAPK/ERK1/2, PI3K/AKT, HIF-1 VEGF) were analyzed by using western blot, immunohistochemistry (IHC), quantitative real-time quantitative PCR (RT-PCR). HepG2 xenograft model and the chorioallantoic membrane (CAM) were used to investigate the effects of Y6 and EGCG on tumors and anti-angiogenesis in vivo. Micro-vessel density (MVD) was analyzed by IHC of CD34 staining. IHC, qRT-PCR and Western blot were used to detect the expression of HIF-1α and VEGF protein in tumor tissues. The protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF in tumor tissues were detected by western blot. RESULTS: Our results demonstrated that both EGCG and Y6 displayed antiangiogenetic and antitumor effects against HCC cells in vitro and in vivo. We found that rather than equal amount of EGCG, Y6 displayed better abilities in inhibiting the growth of HCC tumor cells, as well as inhibiting the growth of neovascularization in the chick embryos and HepG2 xenograft tumors bearing-mice, based on the data obtained from MTT assay, immunohistochemistry (IHC), chick chorioallantoic membrane (CAM) assays. In the comparison of equivalent dose of EGCG, qRT-PCR data showed that Y6 induced more significant decrease of the mRNA levels of HIF-1α and VEGF in supernatant-treated SMMC-7721 cells under hypoxic condition, as well as in the in xenograft tumor tissues; whereas Y6 also significantly reduced the protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF to a greater extent than EGCG, determined by western blotting assay. CONCLUSIONS: our work suggests that the new EGCG derivate Y6 could significantly inhibit tumor growth and angiogenesis which is possibly involved with the signaling intervention of MAPK/ERK1/2 and PI3K/AKT/HIF-1α/VEGF pathways, and is supposed to be a potential therapeutic reagent for anti-angiogenesis treatment of solid tumors.

Saponins isolated from Schizocapsa plantaginea inhibit human hepatocellular carcinoma cell growth in vivo and in vitro via mitogen-activated protein kinase signaling.

The underground cane of Schizocapsa plantaginea (Hance) has long been used by Chinese ethnic minority as a constituent of anti-cancer formulae. Saponins are abundant secondary metabolic products located in the underground cane of this plant. The potential therapeutic effects of total saponins isolated from Schizocapsa plantaginea (Hance) (SSPH) on human hepatocellular carcinoma (HCC) were tested in vitro in human liver cancer cell lines, SMMC-7721 and Bel-7404. Apoptosis and cell cycle arrest were determined using flow cytometry, caspase activation was determined by ELISA, and PARP, cleaved PARP, mitogen-activated protein kinase (MAPK) expression and phosphorylation were measured using Western blotting analysis. In vivo anti-HCC effects of SSPH were verified in nude mouse xenograft model. SSPH exerted markedly inhibitory effect on HCC cell proliferation in time- and concentration-dependent manner. Moreover, SSPH significantly induced apoptosis through caspase-dependent signaling and arrested cell cycle at G2/M phase. These anti-proliferation effects of SSPH were associated with up-regulated phosphorylation of extracellular signal-regulated kinase-1/2 (Erk1/2) and c-jun-NH2-kinase-1/2 (JNK1/2) and reduced phosphorylation of p38MAPK. Furthermore, inhibitors of ERK, UO126, and JNK, SP600125 inhibited the anti-proliferation effects by SSPH, suggesting that Erk and JNK were the effector molecules in SSPH induced anti-proliferative action. During in vivo experiments, SSPH was found to inhibit xenograft tumor growth in nude mice, with a similar mechanism in vitro. Our study confirmed that SSPH exerted antagonistic effects on human liver cancer cells both in vitro and in vivo. Molecular mechanisms underlying SSPH action might be closely associated with MAPK signaling pathways. These results indicated that SSPH has potential therapeutic effects on HCC.