beta-escin and Leukemia--Myelogenous--Chronic--BCR-ABL-Positive

Agents that can enhance tumor cell apoptosis and inhibit invasion have potential for the treatment of cancer. Here, we report the identification of escin, a pentacyclic triterpenoid from horse chestnut that exhibits antitumor potential against leukemia and multiple myeloma. Whether examined by esterase staining, phosphatidyl-serine staining, DNA breakage, or caspase-mediated poly(ADP-ribose) polymerase cleavage, escin potentiated tumor necrosis factor (TNF)-induced apoptosis but inhibited tumor cell invasion. This correlated with the down-regulation of bcl-2, cellular inhibitor of apoptosis protein-2, cyclin D1, cyclooxygenase-2, intercellular adhesion molecule-1, matrix metalloproteinase-9, and vascular endothelial growth factor, which are all regulated by the activation of the transcription factor NF-kappaB. When examined by electrophoretic mobility shift assay, the triterpenoid suppressed nuclear factor-kappaB (NF-kappaB) activation induced by TNF and other inflammatory agents, and this correlated with the inhibition of IkappaBalpha phosphorylation and degradation, inhibition of IkappaB kinase complex (IKK) activation, suppression of p65 phosphorylation and nuclear translocation, and abrogation of NF-kappaB-dependent reporter activity. Overall, our results demonstrate that escin inhibits activation of NF-kappaB through inhibition of IKK, leading to down-regulation of NF-kappaB-regulated cell survival and metastatic gene products and thus resulting in sensitization of cells to cytokines and chemotherapeutic agents.

Topics: Annexin A5; Apoptosis; Cell Line, Tumor; DNA Primers; Escin; Gene Expression Regulation; Genes, Reporter; Humans; Kidney Neoplasms; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Mutagenesis; Neoplasm Invasiveness; NF-kappa B; Signal Transduction; Transcription, Genetic

Beta-aescin, a natural triterpenoid saponin isolated from the seed of Chinese horse chestnut (Aesculus chinensis), is known to generate a wide variety of biochemical and pharmacological effects. In the present study, the authors investigated the anti-proliferative and apoptotic effects of beta-aescin in human chronic myeloid leukemia K562 cell line in vitro. The anti-proliferative effects were detected by CFU-K562 colony formation and cell viability assay. The apoptotic effects were analysed by morphological analysis, annexin V assay, DNA fragmentation assay and flow cytometry DNA content analysis. The results showed that beta-aescin exhibited potent dose- and time-dependent anti-proliferative effects in K562 cells. Morphological evidence of apoptosis, a significant increase of annexin V+ and PI- cells (early apoptotic) and apoptotic DNA fragmentation, were observed in cells treated with beta-aescin. Flow cytometry analysis revealed that beta-aescin could lead to an accumulation of sub G1 population in K562 cells, and suggesting a potential G1 phase accumulation in cell cycle profile of K562 cells. Our findings revealed that beta-aescin is a potent natural inhibitor of proliferation and inducer of apoptosis in K562 cells, and beta-aescin may be a candidate lead compound to explore potential antileukemia drugs.

Topics: Antineoplastic Agents; Apoptosis; Cell Proliferation; Dose-Response Relationship, Drug; Escin; G1 Phase; Humans; K562 Cells; Kinetics; Leukemia, Myelogenous, Chronic, BCR-ABL Positive