Translation Elongation Factor eEF1A2 is a Novel Anticancer Target for the Marine Natural Product Plitidepsin

Abstract

eEF1A2 is one of the isoforms of the alpha subunit of the eukaryotic Elongation Factor 1. It is overexpressed in human tumors and is endowed with oncogenic properties, favoring tumor cell proliferation while inhibiting apoptosis. We demonstrate that plitidepsin, an antitumor agent of marine origin that has successfully completed a phase-III clinical trial for multiple myeloma, exerts its antitumor activity by targeting eEF1A2. The drug interacts with eEF1A2 with a KD of 80 nM and a target residence time of circa 9 min. This protein was also identified as capable of binding [14C]-plitidepsin in a cell lysate from K-562 tumor cells. A molecular modelling approach was used to identify a favorable binding site for plitidepsin at the interface between domains 1 and 2 of eEF1A2 in the GTP conformation. Three tumor cell lines selected for at least 100-fold more resistance to plitidepsin than their respective parental cells showed reduced levels of eEF1A2 protein. Ectopic expression of eEF1A2 in resistant cells restored the sensitivity to plitidepsin. FLIM-phasor FRET experiments demonstrated that plitidepsin localizes in tumor cells sufficiently close to eEF1A2 as to suggest the formation of drug-protein complexes in living cells. Altogether, our results strongly suggest that eEF1A2 is the primary target of plitidepsin.

Undifferentiated small round cell sarcoma in a young male: a case report

“…eEF1A1 is reported to be a negative regulator p53 and p73 and leading to chemoresistance (Blanch et al 2013), and the ubiquitin-like protein FAT10 has been shown to bind eEF1A1 which stabilizes the expression of eEF1A1 in favor of tumor cell proliferation (Liu et al 2016). The isoform eEF1A1 shares 96% homology with the isoform eEF1A2, the primary target of plitidepsin (dehydrodidemnin B/Aplidin, PharmaMar), an antitumor agent of marine origin (Losada et al 2016). eEF1A isoforms were the only proteins detected as capable of binding plitidepsin, and sensitivity was dependent on eEF1A2 levels.…”

From Seabed to Bedside: A Review on Promising Marine Anticancer Compounds

“…Such interaction inhibits the pro-oncogenic behavior of eEF1A2. Interestingly, eEF1A2 is overexpressed in many malignancies, including multiple myeloma (MM) [145]. In vitro studies showed that Plitidepsin elicits strong cytotoxic activity in several cancer cell lines, presenting IC 50 values ≤1 nM [146], and in vivo studies demonstrated the potent antiproliferative effects of Plitidepsin in xenograft models of MM [147].…”

Structural Biomedicine: Characterization of the Structural Basis in Protein-Drug Recognition in Different Human Diseases

“…Binding of plitidepsin (i.e. dehydrodidemnin B) to this same site in the closely related eEF1A2 is believed to stabilize the "active" conformation of eEF1A2 (Losada, et al, 2016), perhaps by preventing dimer formation. (Sánchez-Murcia, Cortés-Cabrera and Gago, 2017).…”

“…Despite the training in the purification of this protein from its natural source, this step was optimized and routinely executed at PharmaMar's facilities. The protocol followed for extraction and purification of eEF1A2 is reported by Losada, A. et al (2016).…”

“…Due to the oncogenic properties of eEF1A2 and the previous reports on eEF1A2 binding plitidepsin in its GTP conformation (Losada, et al, 2016), we aimed for the structural determination of eEF1A2:GTP:plitidepsin ternary complex in order to characterize the binding of this didemnin B derivative.…”