silvestrol and Neoplasms

The translation initiation factor eIF4E mediates a rate-limiting process that drives selective translation of many oncongenic proteins such as cyclin D1, survivin and VEGF, thereby contributing to tumour growth, metastasis and therapy resistance. As an essential regulatory hub in cancer signalling network, many oncogenic signalling pathways appear to converge on eIF4E. Therefore, targeting eIF4E-mediated cap-dependent translation is considered a promising anticancer strategy. This paper reviews the strategies that can be used to target eIF4E, highlighting agents that target eIF4E activity at each distinct level.

Topics: Animals; Antineoplastic Agents; Cyclin D1; Epoxy Compounds; Eukaryotic Initiation Factor-4E; Gene Expression Regulation, Neoplastic; Humans; Inhibitor of Apoptosis Proteins; Macrolides; Neoplasms; Oligonucleotides, Antisense; Protein Biosynthesis; Ribavirin; RNA, Small Interfering; Signal Transduction; Sirolimus; Survivin; Thiazoles; Triterpenes; Vascular Endothelial Growth Factor A

The malignant phenotype is largely the consequence of dysregulated gene expression. Transformed cells depend upon not just a global increase in protein synthesis but an altered translational landscape in which pro-oncogenic mRNAs are translationally up-regulated. Such mRNAs have been shown to possess longer and more structured 5'-UTRs requiring high levels of eukaryotic initiation factor 4A (eIF4A) helicase activity for efficient translation. As such there is a developing focus on targeting eIF4A as a cancer therapy. In order for such treatments to be successful, we must develop a detailed understanding of the mechanisms which make specific mRNAs more dependent on eIF4A activity than others. It is also crucial to fully characterize the potentially distinct roles of eIF4A1 and eIF4A2, which until recently were thought to be functionally interchangeable. This review will highlight the recent advances made in this field that address these issues.

Topics: Epoxy Compounds; Eukaryotic Initiation Factor-4A; Gene Expression Regulation, Neoplastic; Humans; Macrolides; Molecular Targeted Therapy; Neoplasms; Protein Biosynthesis; Protein Isoforms; Sterols; Thiazoles; Triterpenes

Deregulated translation initiation is implicated extensively in cancer initiation and progression. Several translation initiation factors cooperate with known oncogenes, are elevated in human tumors and have been implicated in drug resistance. Consequently, there is a great deal of interest in targeting this process to develop new chemotherapeutics, especially since clinical trial results have been mixed when targeting upstream pathways, such as the mammalian target of rapamycin. Several inhibitors have been characterized over the last 5 years that target the ribosome recruitment phase (eukaryotic initiation factor [eIF]4E [antisense oligonucleotides and 4EGI-1] or eIF4A [pateamine A, hippuristanol and silvestrol]), some of which demonstrate activity in preclinical cancer models. The promise of these inhibitors as chemotherapeutics highlights the importance of targeting this pathway and supports efforts aimed at identifying the most susceptible targets. In addition, the framework in which translation inhibitors would be best employed (i.e., as single agents or as adjuvant therapy) in the clinic remains to be explored systematically. Small-molecule inhibitors of translation initiation are validating the idea that protein synthesis is a legitimate target for curtailing tumor growth.

Topics: Antineoplastic Agents; Epoxy Compounds; Eukaryotic Initiation Factor-4A; Eukaryotic Initiation Factor-4E; Humans; Hydrazones; Macrolides; Neoplasms; Nitro Compounds; Oligonucleotides, Antisense; Protein Biosynthesis; Sterols; Thiazoles; Triterpenes

Overexpression of murine double minute 2 (MDM2) results in the inactivation of p53 and causes cancer which is a leading cause of death in recent era. In recent decades, much attention has been paid to discover potential inhibitors against MDM2 in order to cure cancer. Outcomes from studies proposes that the MDM2 is a hot target to screen potent antagonists. Thus, this study aims at discovering natural compounds using several computational approaches to inhibit the MDM2 and to eliminate p53-MDM2 interaction, which would result in the reactivation of p53 activity. A library of 500 terpenes was prepared and several virtual screening approaches were employed to find out the best hits which could serve as p53-MDM2 antagonists. On the basis of the designed protocol, three terpenes were selected. In the present study, for the stability and validation of selected three protein-ligand complexes 20 ns molecular dynamics simulations and principal component analyses (PCA) were performed. Results found that the selected terpenes hits (3-

Topics: Computer Simulation; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Humans; Molecular Dynamics Simulation; Neoplasms; Oleanolic Acid; Principal Component Analysis; Proto-Oncogene Proteins c-mdm2; Structure-Activity Relationship; Terpenes; Triterpenes; Up-Regulation