ABSTRACT
Translation initiation is a fine-tuned process that plays a critical role in tumorigenesis. The use of small molecules that modulate mRNA translation provides tool compounds to explore the mechanism of translational initiation and to further validate protein synthesis as a potential pharmaceutical target for cancer therapeutics. This report describes the development and use of a click beetle, dual luciferase cell-based assay multiplexed with a measure of compound toxicity using resazurin to evaluate the differential effect of natural products on cap-dependent or internal ribosome entry site (IRES)-mediated translation initiation and cell viability. This screen identified a series of cardiac glycosides as inhibitors of IRES-mediated translation using, in particular, the oncogene mRNA c-Myc IRES. Treatment of c-Myc-dependent cancer cells with these compounds showed a decrease in c-Myc protein associated with a significant modulation of cell viability. These findings suggest that inhibition of IRES-mediated translation initiation may be a strategy to inhibit c-Myc-driven tumorigenesis.
Subject(s)
Cardiac Glycosides/analysis , Cardiac Glycosides/pharmacology , Drug Evaluation, Preclinical , Protein Biosynthesis/drug effects , Protein Synthesis Inhibitors/pharmacology , Proto-Oncogene Proteins c-myc/metabolism , Ribosomes/metabolism , Apoptosis/drug effects , Base Sequence , Biological Assay , Cardiac Glycosides/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Cymarine/chemistry , Cymarine/pharmacology , DNA Damage , Genes, Reporter , HEK293 Cells , Humans , Inhibitory Concentration 50 , Protein Synthesis Inhibitors/analysis , Protein Synthesis Inhibitors/chemistry , Proto-Oncogene Proteins c-myc/antagonists & inhibitors , Ribosomes/drug effects , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Two new compounds, along with two known compounds, were isolated from the barks of Parabarium huaitingii, and their structures were determined as 5α-pregn-6-ene-3ß,17α,20(S)-triol-20-O-ß-d-digitoxopyranoside (1), cymaropyranurolactone 4-O-ß-d-digitalopyranosyl-(1 â 4)-O-ß-d-cymaropyranosyl-(1 â 4)-O-ß-d-oleandropyranosyl-(1 â 4)-O-ß-d-cymaropyranoside (2), 3ß,17α,20(S)-trihydroxy-5α-pregn-6-ene (3), and 5α-pregn-6-ene-3ß,17α,20(S)-triol-3-O-ß-d-digitalopyranoside (4) by spectroscopic methods.
Subject(s)
Antineoplastic Agents, Phytogenic/isolation & purification , Apocynaceae/chemistry , Cymarine/analogs & derivatives , Drugs, Chinese Herbal/isolation & purification , Glycosides/isolation & purification , Pregnanes/isolation & purification , Pregnenes/isolation & purification , Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/pharmacology , Cymarine/chemistry , Cymarine/isolation & purification , Cymarine/pharmacology , Drug Screening Assays, Antitumor , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/pharmacology , Glycosides/chemistry , Glycosides/pharmacology , HeLa Cells , Humans , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Plant Bark/chemistry , Pregnanes/chemistry , Pregnanes/pharmacology , Pregnenes/chemistry , Pregnenes/pharmacology , StereoisomerismABSTRACT
Antiangiogenic activity-guided fractionation and isolation carried out on the methanol extract of Adonis amurensis led to the identification of three compounds, namely cymarin, cymarol, and cymarilic acid. Amongst the three compounds, cymarilic acid was isolated from this plant for the first time. This compound showed no significant cytotoxicity against tumor cell lines but was found to be strongly inhibitory toward tube formation induced by human umbilical venous endothelial (HUVE) cells. Cymarin and cymarol exhibited potent cytotoxicity against a human solid tumor cell line A549 (human lung carcinoma), while being inactive on murine leukemic cells (L1210).
