Targeting of eEF1A withAmaryllidaceaeisocarbostyrils as a strategy to combat melanomas

Abstract

Melanomas display poor response rates to adjuvant therapies because of their intrinsic resistance to proapoptotic stimuli. This study indicates that such resistance can be overcome, at least partly, through the targeting of eEF1A elongation factor with narciclasine, an Amaryllidaceae isocarbostyril controlling plant growth. Narciclasine displays IC(50) growth inhibitory values between 30-100 nM in melanoma cell lines, irrespective of their levels of resistance to proapoptotic stimuli. Normal noncancerous cell lines are much less affected. At nontoxic doses, narciclasine also significantly improves (P=0.004) the survival of mice bearing metastatic apoptosis-resistant melanoma xenografts in their brain. The eEF1A targeting with narciclasine (50 nM) leads to 1) marked actin cytoskeleton disorganization, resulting in cytokinesis impairment, and 2) protein synthesis impairment (elongation and initiation steps), whereas apoptosis is induced at higher doses only (≥200 nM). In addition to molecular docking validation and identification of potential binding sites, we biochemically confirmed that narciclasine directly binds to human recombinant and yeast-purified eEF1A in a nanomolar range, but not to actin or elongation factor 2, and that 5 nM narciclasine is sufficient to impair eEF1A-related actin bundling activity. eEF1A is thus a potential target to combat melanomas regardless of their apoptosis-sensitivity, and this finding reconciles the pleiotropic cytostatic of narciclasine. -

Evidence That Eukaryotic Translation Elongation Factor 1A (eEF1A) Binds the Gcn2 Protein C Terminus and Inhibits Gcn2 Activity*

“…The key role for Gcn2 in regulating protein synthesis and many additional key processes in higher eukaryotes, such as memory formation and the immune system (34,35), together with protein synthesis being central to life, underscore the importance of further elucidating the connections between translation elongation factors and GAAC. Interestingly, eEF1A has been linked to many diseases, including cancer (36,37), and Gcn2 has been implicated in the cell cycle (38). Furthermore, eEF1A is known to have many additional functions outside of protein synthesis, such as regulating the actin cytoskeleton, apoptosis, and protein degradation (26), raising the intriguing possibility that eEF1A may be involved in fine-tuning Gcn2 activity to various cellular conditions.…”

Yeast Translation Elongation Factor-1A Binds Vacuole-localized Rho1p to Facilitate Membrane Integrity through F-actin Remodeling

“…Narciclasine is a small drug-like molecule that binds eEF1A and inhibits its actin bundling activity (39). Lat B binds actin monomers, triggering F-actin depolymerization (40).…”

5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells

“…1), are of interest due to their promising anticancer properties [21]. Thus, narciclasine and lycorine have been actively investigated for their potent anti-tumor effects, both in vitro and in vivo , in various pre-clinical models of human cancers by many research groups [22–30], including their evaluation as cytostatic agents active against apoptosis-resistant cancers by us [31–37]. The anti-proliferative activity of the crinine-type alkaloids has also been reported by natural product chemists on numerous occasions [38–44].…”