Therapeutic suppression of translation initiation factor eIF4E expression reduces tumor growth without toxicity
Jeremy R. Graff, … , Julia H. Carter, Eric G. Marcusson
Jeremy R. Graff, … , Julia H. Carter, Eric G. Marcusson
Published September 4, 2007
Citation Information: J Clin Invest. 2007;117(9):2638-2648. https://doi.org/10.1172/JCI32044.
View: Text | PDF
Research Article

Therapeutic suppression of translation initiation factor eIF4E expression reduces tumor growth without toxicity

Abstract

Expression of eukaryotic translation initiation factor 4E (eIF4E) is commonly elevated in human and experimental cancers, promoting angiogenesis and tumor growth. Elevated eIF4E levels selectively increase translation of growth factors important in malignancy (e.g., VEGF, cyclin D1) and is thereby an attractive anticancer therapeutic target. Yet to date, no eIF4E-specific therapy has been developed. Herein we report development of eIF4E-specific antisense oligonucleotides (ASOs) designed to have the necessary tissue stability and nuclease resistance required for systemic anticancer therapy. In mammalian cultured cells, these ASOs specifically targeted the eIF4E mRNA for destruction, repressing expression of eIF4E-regulated proteins (e.g., VEGF, cyclin D1, survivin, c-myc, Bcl-2), inducing apoptosis, and preventing endothelial cells from forming vessel-like structures. Most importantly, intravenous ASO administration selectively and significantly reduced eIF4E expression in human tumor xenografts, significantly suppressing tumor growth. Because these ASOs also target murine eIF4E, we assessed the impact of eIF4E reduction in normal tissues. Despite reducing eIF4E levels by 80% in mouse liver, eIF4E-specific ASO administration did not affect body weight, organ weight, or liver transaminase levels, thereby providing the first in vivo evidence that cancers may be more susceptible to eIF4E inhibition than normal tissues. These data have prompted eIF4E-specific ASO clinical trials for the treatment of human cancers.

Authors

Jeremy R. Graff, Bruce W. Konicek, Thomas M. Vincent, Rebecca L. Lynch, David Monteith, Spring N. Weir, Phil Schwier, Andrew Capen, Robin L. Goode, Michele S. Dowless, Yuefeng Chen, Hong Zhang, Sean Sissons, Karen Cox, Ann M. McNulty, Stephen H. Parsons, Tao Wang, Lillian Sams, Sandaruwan Geeganage, Larry E. Douglass, Blake Lee Neubauer, Nicholas M. Dean, Kerry Blanchard, Jianyong Shou, Louis F. Stancato, Julia H. Carter, Eric G. Marcusson

×

Figure 4

eIF4E ASO transfection induces apoptosis and suppresses endothelial cell tube formation.

Options: View larger image (or click on image) Download as PowerPoint
eIF4E ASO transfection induces apoptosis and suppresses endothelial cel...
(A) MDA-MB-231 human breast cancer cells were transfected for 72 hours with 100 nM 4E-ASO4 or mismatch control. Representative photomicrographs illustrate the dramatic increase in TUNEL staining after 4E-ASO4 transfection. Nuclear staining is revealed by Hoechst dye. (B) The mean percentage of cells positive for TUNEL or activated caspase-3 is depicted for both MDA-MB-231 and H460 non–small cell lung cancer cells (± SEM). Data in A and B are representative of more than 4 separate determinations. (C) HUVECs were plated on Matrigel and transfected with the 4E-ASO4, 4E-ASO2, or non-silencing ASO controls as indicated (ASO ctrlE, 5′-TGTTACAGTCTTGTACCCTT-3′ and "randomer" ASO ctrlF, a random mix of 420 possible 20-mer nucleotide sequences). The formation of vessel-like tubes was scored semi-quantitatively on a scale of 1 to 5. Data are presented as the mean tube score from 4 separate determinations ± SD. (D) Mean eIF4E expression ± SEM was evaluated from parallel plates by quantitative RT-PCR for the controls and the 4E-ASO4–transfected HUVECs. RT-PCR for the cells treated with 4E-ASO2 was not performed. (E) HUVECs were transfected for 48 hours with 150 nM 4E-ASO4 or mismatch control ASO, replated on dermal fibroblasts, and incubated for 6 days to assess the formation of chord-like structures. Endothelial cells were visualized immunohistochemically with an anti-CD31 antibody (green). Hoechst stain reveals the nuclei of the dermal fibroblasts (blue). Western blot analyses of eIF4E expression 48 hours posttransfection are shown. Data are representative of 5 separate experiments.