beta-escin and Liver-Neoplasms

The activation of signal transducer and activator of transcription 3 (STAT3) has been linked with the proliferation, survival, invasion, and angiogenesis of a variety of human cancer cells, including hepatocellular carcinoma (HCC). Agents that can suppress STAT3 activation have potential for the prevention and treatment of HCC. In this study, we tested an agent, beta-escin, for its ability to suppress STAT3 activation. We found that beta-escin, a pentacyclic triterpenoid, inhibited both constitutive and interleukin-6-inducible STAT3 activation in a dose- and time-dependent manner in HCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Vanadate treatment reversed the beta-escin-induced down-regulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that beta-escin induced the expression of tyrosine phosphatase Src homology phosphatase 1 that correlated with the down-regulation of constitutive STAT3 activation. beta-Escin also down-regulated the expression of STAT3-regulated gene products, such as cyclin D1, Bcl-2, Bcl-xL, survivin, Mcl-1, and vascular endothelial growth factor. Finally, beta-escin inhibited proliferation and also substantially potentiated the apoptotic effects of paclitaxel and doxorubicin in HCC cells. Overall, these results suggest that beta-escin is a novel blocker of STAT3 activation that may have potential in the suppression of proliferation and chemosensitization in HCC.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Escin; Humans; Immunohistochemistry; Janus Kinase 2; Liver Neoplasms; Phosphorylation; Signal Transduction; STAT3 Transcription Factor

Escin, a mixture of triterpene saponins extracted from Aesculus wilsonii Rehd., was used to analyze the antitumor effect in hepatocellular carcinoma in vivo and in vitro. At a dose of 2.8 mg/kg, escin had a rather high inhibition ratio (43.5 %) on mice H22 tumor growth in vivo. The results of the SRB cell viability assay showed that escin could induce significant concentration- and time-dependent inhibition of HepG (2) cell viability. Disruption of the G (1)/S phase of cell cycle progression accompanied by the induction of apoptosis were also observed in HepG (2) cells following escin treatment. The results of pulse-field gel electrophoresis and Western blot analysis show the induction of caspase-independent apoptosis by escin. This study provides evidence that escin induces cell cycle checkpoint arrest and caspase-independent cell death in HepG (2) cells, in support of its efficacious potential as a chemopreventive agent.

Topics: Aesculus; Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Carcinoma, Hepatocellular; Cell Cycle; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Escin; Female; Hep G2 Cells; Humans; Liver Neoplasms; Mice; Mice, Inbred Strains; Phytotherapy; Plant Extracts; Xenograft Model Antitumor Assays