The Eif4f Translation Initiation Complex –

Author Manuscript Published OnlineFirst on October 27, 2016; DOI: 10.1158/1078-0432.CCR-14-2362 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited.

Molecular Pathways: the eIF4F Translation Initiation complex –

New Opportunities for Cancer Treatment

Hélène Malka-Mahieu1,2,3,#, Michelle Newman1,2,3,#, Laurent Désaubry4,5, Caroline

Robert6,7,8,*, Stéphan Vagner1,2,3,6,7,*

1Institut Curie, PSL Research University, CNRS UMR 3348, F-91405, Orsay, France ;

2Université Paris Sud, Université Paris-Saclay, CNRS UMR 3348, F-91405 Orsay, France ;

3Equipe Labellisée Ligue Contre le Cancer ; 4Laboratory of Therapeutic Innovation (UMR

7200), Faculty of Pharmacy, University of Strasbourg–CNRS, 67400 Illkirch, France ; 5Sino-

French Joint Lab of Food Nutrition/Safety and Medicinal Chemistry, College of

Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China;

6INSERM U981, Villejuif, France; 7Institut de cancérologie Gustave Roussy, Villejuif,

France; 8Université Paris-Sud, Kremlin-Bicêtre F-94276, France

#First co-authors

*Corresponding authors :

Caroline Robert, INSERM U981, Gustave Roussy, 114, rue Édouard-Vaillant, 94805

Villejuif Cedex, France ; +33 142 11 42 11 ; [email protected]

Stéphan Vagner, CNRS UMR3348, Institut Curie, Université Paris Sud-11 Bâtiment 110,

Centre Universitaire, 91405 Orsay Cedex, France ; +33 169 86 31 03 ;

[email protected]

Running title: eIF4F and cancer

Downloaded from clincancerres.aacrjournals.org on September 26, 2021. © 2016 American Association for Cancer Research. Author Manuscript Published OnlineFirst on October 27, 2016; DOI: 10.1158/1078-0432.CCR-14-2362 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited.

Conflicts of interest: None

Abstract

The eIF4F complex regulates the cap-dependent mRNA translation process. It is becoming

increasingly evident that aberrant activity of this complex is observed in many cancers leading

to the selective synthesis of proteins involved in tumour growth and metastasis. The selective

translation of cellular mRNAs controlled by this complex also contributes to resistance to

cancer treatments, and downregulation of the eIF4F complex components can restore

sensitivity to various cancer therapies. Here we review the contribution of the eIF4F complex

to tumourigenesis with a focus on its role in chemoresistance as well as the promising use of

new small molecule inhibitors of the complex, including flavaglines/rocaglates, hippuristanol

and pateamine A.

Background

Among the different steps in gene expression, cytoplasmic mRNA translation is an

essential process that leads to protein synthesis. Although global translation rates are

generally higher in cancer cells, it is now admitted that subsets of mRNAs are specifically

regulated at the translation level. Excellent reviews have recently been published on the role

of translation in cancer (1-5). Here we focus on the eIF4F complex, its role in

chemoresistance and its targeting with small molecule inhibitors.

The interaction between eIF4F and the 7-methylguanosine ‘cap’ (m7G) located at the

5’ end of all mRNAs is critical to directly recruit the 40S ribosomal subunit to mRNAs

through a set of protein-protein interactions and to unwind RNA secondary structures located

in the 5’ untranslated region (5’UTR) of mRNAs. The eIF4F complex comprises the eIF4E

cap binding protein, the eIF4A DEAD box RNA helicase and the eIF4G scaffolding protein

(Figure 1A). eIF4A utilises ATP hydrolysis to unwind and resolve RNA secondary structures.

While ATP hydrolysis is necessary to the unwinding action, it also releases eIF4A from the

mRNA, meaning it can use another substrate and thus recycling the available eIF4A to

increase the rate of translation. Finally, eIF4G is a scaffold protein for the assembly of the

eIF4F complex. The activity of the eIF4F complex is tightly controlled by its interaction with

several proteins including the eIF4A-binding proteins eIF4B, eIF4H and Programmed Cell

Death 4 PDCD4 (eIF4B and eIF4H stimulate while PDCD4 inhibits eIF4A), the eIF4E-

inhibitory proteins 4EBP1-3, and many eIF4G-interacting proteins (e.g. the poly(A) binding

protein PABP).

Not all mRNAs are similarly selected by the eIF4F complex. eIF4E is implicated in

the translation of long and highly structured mRNAs. Of these mRNAs, many encode proteins

involved in cell cycle progression, cell growth or angiogenesis (e.g myc, CCDN1, ODC1,

VEGF, FGF2) or more generally cancer-related genes (2). The mRNAs that require eIF4A for

their translation were characterised using transcriptome-scale ribosome footprinting (6). Such

mRNAs, which are limited in number, harbor a particularly long 5' untranslated region (UTR)

with guanine-rich motifs that form G-quadruplexes, such as the 12-nucleotide (CGG)4 motif,

that form a four-stranded structure. Importantly, most of these mRNAs encode for oncogenes,

transcription factors, epigenetic regulators and kinases, while housekeeping genes do not

display G-quadruplexes and do not require eIF4A for their translation.

The eIF4F complex is located at the convergence of several cell signaling pathways involved

in carcinogenesis, including the PI(3)K/AKT/mTOR pathway and the RAS-RAF-MEK-ERK-

MNK mitogen-activated protein kinase (MAPK) (Figure 1B). When phosphorylated by

mTORC1, the 4EBP proteins are unable to bind eIF4E, enabling the formation of an effective

eIF4E-eIF4G complex. mTORC1 is also responsible for the phosphorylation of the S6K1/2

kinases which phosphorylate (i) the eIF4A-inhibitory protein, PDCD4, relieving the inhibitory

activity of PDCD4 on eIF4A; and (ii) eIF4B, allowing it to interact with eIF4A to enhance its

helicase activity. In the MAPK pathway, ERK influences the translation via the activation of

the RSK kinases that target PDCD4 and S6, independently of the S6K kinases. MNK,

downstream of ERK, controls the phosphorylation of eIF4E on a single site (Ser209), through

its interaction with eIF4G. Strong evidence links eIF4E phosphorylation with tumourigenesis,

invasion and metastatic progression in cells and in mice models (7-10).

In parallel to these phosphorylation events, the expression of the components of the

eIF4F complex is also regulated. For instance the MYC transcription factor, one of the most

frequently activated oncogene in human cancers, increases the transcription of all genes

encoding components of the eIF4F complex (eIF4E, eIF4A and eIF4G), thereby controlling

protein translation. Other transcription factors can also regulate the transcription of the

individual components of the translation complex following stimulation by various growth

factor pathways (Supplementary Table 1).

The eIF4F complex contributes to many of the ‘hallmarks of cancer’ such as sustained

proliferative signalling, evasion of growth suppression, resistance to programmed cell death,

replicative immortality, angiogenesis, invasion and metastasis. Each of the individual

components of the complex have been described as prognostic indicators. Expression levels of

the eIF4F complex components and their inhibitors as well as phosphorylation can be linked

with the aggressiveness of histological subtypes of cancers, poor disease outcome and

survival and response to treatment (Supplementary Table 2).

Clinical-Translational advances

eIF4F and resistance to anti-cancer therapies

During the last decade, it has been demonstrated that the activity of the eIF4F complex

contributes to drive resistance to many types of therapies used as treatment in cancer. One of

the first examples was shown in Eµ-Myc hematopoietic stem cells (HSCs) transfected with

retroviral vectors expressing eIF4E. Lymphoma cells overexpressing the cap-binding protein

are highly resistant to the DNA-damaging agent doxorubicin compared to controls (11), and

this observation has since been extended to other types of therapies. Knockdown of eIF4E

results in enhanced chemosensitivity to cisplatin and antimitotic microtubule stabilizers (e.g.

placlitaxel, docetaxel) in triple-negative breast cancer cells (12). In addition, increased

expression of miR141, which targets eIF4E, has also been observed in an acquired model of

docetaxel resistance in breast cancer (13).

eIF4E overexpression or amplification also promotes resistance to PI3K/Akt/mTOR

inhibitors (e.g. AZD8055, BEZ235) in immortalized mammary epithelial cells or colon cancer

cells (14, 15) and ectopic expression of eIF4E leads to resistance to inhibitors of receptor

tyrosine kinases (e.g. trastuzumab, cetuximab or erlotinib) in breast cancer xenografts (16).

Furthermore, phosphorylation of eIF4E has been implicated in resistance to cisplatin in breast

cancer cell lines and immortalized keratinocytes. Interestingly, this resistance to cisplatin is

abolished in cancer cells that no longer have an interaction between p-eIF4E and 4E-T, which

mediates eIF4E nuclear import, indicating that phosphorylation of eIF4E and its interaction

with 4E-T are involved in the tolerance to increased DNA damage(17).

The eIF4A inhibitory protein PDCD4 can also contribute to chemoresistance. Indeed,

re-expression of PDCD4 sensitises glioblastoma multiforme cells to doxorubicin via Bcl-xL

inhibition (18) and, conversely, low PDCD4 expression is associated with resistance to

paclitaxel and doxorubicin (19).

eIF4A itself is not directly involved in resistance mechanisms, but deregulation of its

activity leads to chemosensitivity in many cancer types as illustrated in Table S1. Inhibition of

eIF4A binding to mRNA, of its recycling or increase of its ATPase activity contribute to

sensitisation in many murine cancer models and highlights the importance of this initiation

factor in this process (Table S1). This aspect will be expanded further in the following

section.

eIF4A co-factors, eIF4B and eIF4H, are also involved in chemosensitivity. Overexpression of

both eIF4H isoforms inhibits caspase activity after cisplatin and etoposide treatment in murine

NIH3T3 cells (20). In addition, eIF4B is overexpressed in cisplatin / fluorouracil resistant

gastric tumours (21). Finally, resistance to anti-BRAF and anti-MEK therapies is associated

with a prominently active eIF4F complex in a BRAF(V600)-mutated context (22).

Inhibitors of the eIF4F complex

The first strategy to decrease eIF4F activity has been to target eIF4E, which is the least

abundant factor of the complex. Targeting eIF4E with an antisense oligonucleotide (4EASO)

has shown a significant antineoplastic effect, where tumour growth in a prostate xenograft

model was supressed, as was the formation of vessel-like structures, suggesting an additional

anti-angiogenic effect (23). Clinical trials with this inhibitor produced few adverse effects but

no significant clinical response on tumours (24). Therefore, while targeting eIF4E appears to

be an attractive treatment, its effect as a single-agent, at least using the aforementioned anti-

sense technology, was not effective.

Another strategy to block eIF4E activity is to target the eIF4E-cap interaction. The

pronucleotide 4Ei-1 (N-7 benzyl guanosine monophosphate tryptamine phosphoramidate

pronucleotide) in combination with non-toxic levels of gemcitabine has been trialled in breast

and lung cancer cells, which resulted in chemo sensitisation of the cell lines (25).

Specifically disrupting the eIF4E-eIF4G interaction has yielded promising results. The first

compound used was 4EGI-1, identified by a high-throuput screening assay in 2007 (26). This

drug induces apoptotic cell death in several tumour cell lines in vitro (26, 27) and promotes

tumour regression of breast or melanoma cancer xenografts in vivo (28), while another

eIF4E-eIF4G inhibitor 4E1RCat, promotes tumour-free survival in combination with

doxorubicin (29).

Three classes of eIF4A inhibitors have been reported so far. Flavaglines, hippuristanol and

pateamine A all originate from natural products that display potent anticancer effects in vivo.

Rocaglamide (Flavaglines) was isolated in 1992 from Asian medicinal plants based on their

potent antileukemic activities (30). Since then, more than 100 natural flavaglines such as

rocaglaol or silvestrol have been identified, and many have been shown to display potent

anticancer effects in murine models of cancers (31, 32). The most studied is silvestrol,

unfortunately, this compound shows poor bioavailability coupled with high sensitivity to

multidrug resistance (33). Gratifyingly, more drug-like compounds that are insensitive to

multidrug resistance displaying enhanced in vivo anticancer activities have been reported. For

instance FL3 was shown to overcome the resistance to BRAF inhibitors in mouse models of

metastatic melanoma (22).

Many of the studies listed in Supplementary Table 3 have demonstrated that flavaglines

strongly potentiate in vivo the antitumour effects of chemotherapeutic agents, in particular in

mouse models of chemoresistant cancers.

Remarkably, flavaglines have also been shown to bind the scaffold proteins prohibitins,

blocking their interaction with CRAF which results in inhibition of the RAS-CRAF-MEK-

ERK signalling pathway that is critical to the survival of the cancer cells (34). However, the

identification of a drug-resistant and functional eIF4A1 allele that abolishes the cytotoxicity

of flavaglines upon introduction into cells using the CRISPR/Cas9 technology, suggests that

eIF4A is the prime target of flavaglines in most of the cancers (35).

Flavaglines were shown to block eIF4A recycling due to its increased binding to mRNAs

(36). The direct interaction with eIF4A was shown using affinity chromatography (37) and

chemogenomic profiling in yeast (38). As mentioned in the previous section, mRNAs which

require eIF4A for their translation encode for cancer-related proteins. Hence, this observation

clarifies why eIF4A inhibitors display a cytotoxicity that is specific to cancer cells. In

contrast, it has been shown that flavagline sensitivity is poorly related to the presence of the

G-quadruplexes in the 5’UTR, but depends strongly on polypurine sequences in these regions

(39).

Hippuristanol is a complex polyoxygenated steroid originally isolated in 1981 from coral (40).

This compound allosterically inhibits the binding of mRNA to eIF4A (41, 42). Recent

biophysical studies using FRET indicate that hippuristanol locks eIF4AI in a closed

conformation to inhibit RNA unwinding (43). In vivo studies showed that hippuristanol

significantly inhibits the growth of primary effusion lymphoma in xenografted mice (44),

suppress T-cell tumour growth (45), and induce a synergistic response with a Bcl-2 inhibitor

(ABT-737) resulting in the induction of apoptosis in lymphoma or leukaemia cells (46).

Hippuristanol has also been shown to induce cell cycle arrest and apoptosis in vitro by

reducing the expression of cell cycle regulators (such as cyclin D1/D2, CDK4 and CDK6), or

pro-survival factors (such as Bcl-xl)(45). Moreover, it is capable of reversing drug resistance

in PI3K/Akt/mTOR-dependent tumours (46).

Pateamine A is a complex macrolide that was isolated from a marine sponge in 1991, with

demonstrated in vitro cytotoxicity against leukemia cells (47). Pateamine A prevents eIF4A

heterodimerization with eIF4G, but surprisingly, enhances the helicase and ATPase activities

of eIF4A (48, 49). Exploration of the structural requirements of pateamine A for its

pharmacological activities led to the identification of desmethyl, desamino pateamine A as a

structurally simplified analogue that significantly induced tumour regression in two mouse

models of melanoma (50).

Conclusions

Based on their consistent anticancer activity, eIF4F complex inhibitors should be considered

for further clinical development. It will be important to define biomarkers to determine which

subgroup of patients will be sensitive to these inhibitors. Some reports are already showing

that response to treatment can be predicted using the eIF4F complex, and using prognostic

factors combined with newer inhibitors may yield better responses to treatment.

Although targeting eIF4E has shown impressive effects on tumour progression in vivo, its

clinical application has to be improved. Combining eIF4E inhibitors with other therapies

seems a promising strategy to be tested (phase 2 trials of 4E-ASO in combination with

established chemotherapies are ongoing - NCT01234038 and NCT 01234025). Furthermore,

the use of both in vitro assays and in vivo mouse models are paving the way to develop new

combinations of eIF4F inhibitors with validated chemotherapies.

The reviewed studies on flavaglines, hippuristanol and pateamine A strongly suggest that

eIF4A is a valid target in oncology. The promise of these compounds is poised to promote the

advancement of derivatives of these natural products towards the clinic. It also highlights the

resurgence of natural products in oncology. Indeed, the advent of targeted therapies in the

1990's placed the clinical study of anticancer natural products in limbo for a decade, until it

appeared that targeted therapies would not fulfil expectations for many solid tumours. Thus,

since 2007 twelve novel natural product derivatives have been approved to treat cancers,

indicating that natural products continue to provide valid opportunities to treat unmet medical

needs.

Acknowledgements

We apologize to all colleagues who have made contributions in the field and could not be

cited owing to space constraints.

Figure Legends

Figure 1. Convergence of major signaling pathways involved in cancer towards eIF4F

complex. A. eIF4F complex comprises three proteins : the cap-binding protein eIF4E, the

DEAD box RNA helicase eIF4A and the scaffolding protein eIF4G. This complex is

negatively regulated by 4EBP1-3 (eIF4E inhibitors) and PDCD4 (eIF4A inhibitor) and

actively regulated by eIF4B and eIF4H (eIF4A co-factors). B eIF4F complex comprising

eIF4E, eIF4G and eIF4A is regulated by MAPK, PI3K/Akt/mTOR pathways and transcription

factors located downstream of RTKs (Receptor Tyrosine Kinase). Aberrant activation of one

of these pathways leads to oncogenic processes. Consequently many inhibitors (in red) have

been designed to specifically inhibit RTKs, or components of the MAPK or PI3K/mTOR

pathways. The majority of inhibitors indicated in the figure have several targets; only the

main one is indicated. eIF4F is positionned at the convergence of these dysregulated pathways

and is therefore a promising target for many types of cancer.

References

1. Bhat M, Robichaud N, Hulea L, Sonenberg N, Pelletier J, Topisirovic I. Targeting the translation machinery in cancer. Nat Rev Drug Discov. 2015;14:261-78. 2. Pelletier J, Graff J, Ruggero D, Sonenberg N. Targeting the eIF4F translation initiation complex: A critical nexus for cancer development. Cancer Res. 2015;75:250-63. 3. Truitt ML, Ruggero D. New frontiers in translational control of the cancer genome. Nat Rev Cancer. 2016;16:288-304. 4. Hinnebusch AG, Ivanov IP, Sonenberg N. Translational control by 5'-untranslated regions of eukaryotic mRNAs. Science. 2016;352:1413-6. 5. Chu J, Cargnello M, Topisirovic I, Pelletier J. Translation Initiation Factors: Reprogramming Protein Synthesis in Cancer. Trends Cell Biol. 2016. 6. Wolfe AL, Singh K, Zhong Y, Drewe P, Rajasekhar VK, Sanghvi VR, et al. RNA G- quadruplexes cause eIF4A-dependent oncogene translation in cancer. Nature. 2014;513:65- 70. 7. Topisirovic I, Ruiz-Gutierrez M, Borden KL. Phosphorylation of the eukaryotic translation initiation factor eIF4E contributes to its transformation and mRNA transport activities. Cancer Res. 2004;64:8639-42. 8. Wendel HG, Silva RL, Malina A, Mills JR, Zhu H, Ueda T, et al. Dissecting eIF4E action in tumorigenesis. Genes Dev. 2007;21:3232-7. 9. Furic L, Rong L, Larsson O, Koumakpayi IH, Yoshida K, Brueschke A, et al. eIF4E phosphorylation promotes tumorigenesis and is associated with prostate cancer progression. Proc Natl Acad Sci U S A. 2010;107:14134-9. 10. Robichaud N, del Rincon SV, Huor B, Alain T, Petruccelli LA, Hearnden J, et al. Phosphorylation of eIF4E promotes EMT and metastasis via translational control of SNAIL and MMP-3. Oncogene. 2015;34:2032-42. 11. Wendel H-G, Stanchina Ed, Fridman JS, Malina A, Ray S, Kogan S, et al. Survival signalling by Akt and eIF4E in oncogenesis and cancer therapy. Nature. 2004;428:332-7. 12. Zhou F-f, Yan M, Guo G-f, Wang F, Qiu H-j, Zheng F-m, et al. Knockdown of eIF4E suppresses cell growth and migration, enhances chemosensitivity and correlates with increase in Bax/Bcl-2 ratio in triple-negative breast cancer cells. Med Oncol. 2011;28:1302-7. 13. Yao YS, Qiu WS, Yao RY, Zhang Q, Zhuang LK, Zhou F, et al. miR-141 confers docetaxel chemoresistance of breast cancer cells via regulation of EIF4E expression. Oncol Rep. 2015;33:2504-12.

14. Cope CL, Gilley R, Balmanno K, Sale MJ, Howarth KD, Hampson M, et al. Adaptation to mTOR kinase inhibitors by amplification of eIF4E to maintain cap-dependent translation. J Cell Sci. 2014;127:788-800. 15. Ilic N, Utermark T, Widlund HR, Roberts TM. PI3K-targeted therapy can be evaded by gene amplification along the MYC-eukaryotic translation initiation factor 4E (eIF4E) axis. Proc Natl Acad Sci U S A. 2011;108:E699-E708. 16. Zindy P, Bergé Y, Allal B, Filleron T, Pierredon S, Cammas A, et al. Formation of the eIF4F translation–initiation complex determines sensitivity to anticancer drugs targeting the EGFR and HER2 receptors. Cancer Res. 2011;71:4068-73. 17. Martínez A, Sesé M, Losa JH, Robichaud N, Sonenberg N, Aasen T, et al. Phosphorylation of EiF4E confers resistance to cellular stress and dna-damaging agents through an interaction with 4E-T: a rationale for novel therapeutic approaches. PLoS ONE. 2015;10:e0123352. 18. Liwak U, Jordan LE, Von-Holt SD, Singh P, Hanson JE, Lorimer IA, et al. Loss of PDCD4 contributes to enhanced chemoresistance in Glioblastoma multiforme through de- repression of Bcl-xL translation. Oncotarget. 2013;4:1365-72. 19. Bourguignon LY, Spevak CC, Wong G, Xia W, Gilad E. Hyaluronan-CD44 interaction with protein kinase Cϵ promotes oncogenic signaling by the stem cell marker Nanog and the production of microRNA-21, leading to down-regulation of the tumor suppressor protein PDCD4, anti-apoptosis, and chemotherapy resistance in breast tumor cells. J Biol Chem. 2009;284:26533-46. 20. Vaysse C, Philippe C, Martineau Y, Quelen C, Hieblot C, Renaud C, et al. Key contribution of eIF4H-mediated translational control in tumor promotion. Oncotarget. 2015;6:39924-40. 21. Kim HK, Choi IJ, Kim CG, Kim HS, Oshima A, Michalowski A, et al. A gene expression signature of acquired chemoresistance to cisplatin and fluorouracil combination chemotherapy in gastric cancer patients. PLoS One. 2011;6:e16694. 22. Boussemart L, Malka-Mahieu H, Girault I, Allard D, Hemmingsson O, Tomasic G, et al. eIF4F is a nexus of resistance to anti-BRAF and anti-MEK cancer therapies. Nature. 2014;513:105-9. 23. Graff JR, Konicek BW, Lynch RL, Dumstorf CA, Dowless MS, McNulty AM, et al. eIF4E activation is commonly elevated in advanced human prostate cancers and significantly related to reduced patient survival. Cancer Res. 2009;69:3866-73.

24. Hong DS, Kurzrock R, Oh Y, Wheler J, Naing A, Brail L, et al. A phase 1 dose escalation, pharmacokinetic, and pharmacodynamic evaluation of eIF-4E antisense oligonucleotide LY2275796 in patients with advanced cancer. Clin Cancer Res. 2011;17:6582-91. 25. Li S, Jia Y, Jacobson B, McCauley J, Kratzke R, Bitterman PB, et al. Treatment of breast and lung cancer cells with a N-7 benzyl guanosine monophosphate tryptamine phosphoramidate pronucleotide (4Ei-1) results in chemosensitization to gemcitabine and induced eIF4E proteasomal degradation. Mol Pharm. 2013;10:523-31. 26. Moerke NJ, Aktas H, Chen H, Cantel S, Reibarkh MY, Fahmy A, et al. Small- molecule inhibition of the interaction between the translation initiation factors eIF4E and eIF4G. Cell. 2007;128:257-67. 27. Descamps G, Gomez-Bougie P, Tamburini J, Green A, Bouscary D, Maiga S, et al. The cap-translation inhibitor 4EGI-1 induces apoptosis in multiple myeloma through Noxa induction. Br J Cancer. 2012;106:1660-7. 28. Chen L, Aktas BH, Wang Y, He X, Sahoo R, Zhang N, et al. Tumor suppression by small molecule inhibitors of translation initiation. Oncotarget. 2012;3:869-81. 29. Cencic R, Hall DR, Robert F, Du Y, Min J, Li L, et al. Reversing chemoresistance by small molecule inhibition of the translation initiation complex eIF4F. Proc Natl Acad Sci U S A. 2011;108:1046-51. 30. King ML, Chiang CC, Ling HC, Fujita E, Ochiai M, McPhail AT. X-Ray crystal structure of rocaglamide, a novel antileukemic 1H-cyclopenta[b]benzofuran from Aglaia elliptifolia. Chem Commun. 1992:1150-51. 31. Basmadjian C, Thuaud F, Ribeiro N, Desaubry L. Flavaglines: potent anticancer drugs that target prohibitins and the helicase eIF4A. Future Med Chem. 2013;5:2185-97. 32. Pan L, Woodard JL, Lucas DM, Fuchs JR, Kinghorn AD. Rocaglamide, silvestrol and structurally related bioactive compounds from Aglaia species. Nat Prod Rep. 2014;31:924-39. 33. Gupta SV, Sass EJ, Davis ME, Edwards RB, Lozanski G, Heerema NA, et al. Resistance to the Translation Initiation Inhibitor Silvestrol is Mediated by ABCB1/P- Glycoprotein Overexpression in Acute Lymphoblastic Leukemia Cells. AAPS J. 2011;in press. 34. Polier G, Neumann J, Thuaud F, Ribeiro N, Gelhaus C, Schmidt H, et al. The natural anticancer compounds rocaglamides inhibit the Raf-MEK-ERK pathway by targeting prohibitin 1 and 2. Chem Biol. 2012;19:1093-104.

35. Chu J, Galicia-Vazquez G, Cencic R, Mills JR, Katigbak A, Porco JA, Jr., et al. CRISPR-Mediated Drug-Target Validation Reveals Selective Pharmacological Inhibition of the RNA Helicase, eIF4A. Cell Rep. 2016;15:2340-7. 36. Bordeleau ME, Robert F, Gerard B, Lindqvist L, Chen SM, Wendel HG, et al. Therapeutic suppression of translation initiation modulates chemosensitivity in a mouse lymphoma model. J Clin Invest. 2008 Jul [cited 118 7]; 2008/06/14:[2651-60]. 37. Chambers JM, Lindqvist LM, Webb A, Huang DC, Savage GP, Rizzacasa MA. Synthesis of biotinylated episilvestrol: highly selective targeting of the translation factors eIF4AI/II. Org Lett. 2013;15:1406-9. 38. Sadlish H, Galicia-Vazquez G, Paris CG, Aust T, Bhullar B, Chang L, et al. Evidence for a functionally relevant rocaglamide binding site on the eIF4A-RNA complex. ACS Chem Biol. 2013;8:1519-27. 39. Iwasaki S, Floor SN, Ingolia NT. Rocaglates convert DEAD-box protein eIF4A into a sequence-selective translational repressor. Nature. 2016;advance online publication. 40. Higa T, Tanaka J, Tsukitani Y, Kikuchi H. Hippuristanols, cytotoxic polyoxygenated steroids from the gorgonian Isis hippuris. Chem Lett. 1981:1647-50. 41. Bordeleau ME, Mori A, Oberer M, Lindqvist L, Chard LS, Higa T, et al. Functional characterization of IRESes by an inhibitor of the RNA helicase eIF4A. Nat Chem Biol. 2006;2:213-20. 42. Lindqvist L, Oberer M, Reibarkh M, Cencic R, Bordeleau ME, Vogt E, et al. Selective pharmacological targeting of a DEAD box RNA helicase. PLoS One. 2008;3:e1583. 43. Sun Y, Atas E, Lindqvist LM, Sonenberg N, Pelletier J, Meller A. Single-Molecule Kinetics of the Eukaryotic Initiation Factor 4AI upon RNA Unwinding. Structure. 2014;22:941-8. 44. Ishikawa C, Tanaka J, Katano H, Senba M, Mori N. Hippuristanol reduces the viability of primary effusion lymphoma cells both in vitro and in vivo. Mar Drugs. 2013;11:3410-24. 45. Tsumuraya T, Ishikawa C, Machijima Y, Nakachi S, Senba M, Tanaka J, et al. Effects of hippuristanol, an inhibitor of eIF4A, on adult T-cell leukemia. Biochem Pharmacol. 2011;81:713-22. 46. Cencic R, Robert F, Galicia-Vazquez G, Malina A, Ravindar K, Somaiah R, et al. Modifying chemotherapy response by targeted inhibition of eukaryotic initiation factor 4A. Blood Cancer J. 2013;3:e128.

47. Northcote PT, Blunt JW, Munro MHG. Pateamine: A potent cytotoxin from the New Zealand marine sponge, Myxale sp. Tetrahedron Lett. 1991;32:6411-4. 48. Bordeleau ME, Matthews J, Wojnar JM, Lindqvist L, Novac O, Jankowsky E, et al. Stimulation of mammalian translation initiation factor eIF4A activity by a small molecule inhibitor of eukaryotic translation. Proc Natl Acad Sci U S A. 2005;102:10460-5. 49. Low WK, Dang Y, Schneider-Poetsch T, Shi Z, Choi NS, Merrick WC, et al. Inhibition of eukaryotic translation initiation by the marine natural product pateamine A. Mol Cell. 2005;20:709-22. 50. Kuznetsov G, Xu Q, Rudolph-Owen L, TenDyke K, Liu J, Towle M, et al. Potent in vitro and in vivo anticancer activities of des-methyl, des-amino pateamine A, a synthetic analogue of marine natural product pateamine A. Mol Cancer Ther. 2009;8:1250-60.

Figure 1:

A mRNA

cap 4EBP ORF Poly(A) eIF4E 5’ utr 3’ utr 1/2/3

eIF4A PDCD4 eIF4G eIF4F complex eIF4B

eIF4H

B Lapatinib Lapatinib Cetuximab Neratinib Erlotinib Trastuzumab Lucitanib Geﬁtinib Dovitnib Panitumumab HER2 PI3K AZD4547 BJG398 EGFR Brivanib PTEN FGFR TGFβ-R TNFR BEZ235 Lenvatinib XL765 Motesanib Akt BGT226 Pazopanib VEGFR Regorafenib SMAD4 NF B mTOR κ Rapamycin C/EBPα Everolimus RAS Temsirolimus AZD8055 Trametinib HIFα 4EBP1 Cobimetinib eIF4E AZD6244 MYC PD0325901 C/EBPβ RAF ERKMEK MNK 4E-ASO 4EGI-1 4E1RCat Sp1 Vemurafenib Cercosporamide 4E2RCat eIF4G Dabrafenib CGP57380 Hippuristanol Pateamine A Ets eIF4B Silvestrol FL3 RSK MYC eIF4A S6 PDCD4

S6K RSK

Molecular Pathways: The eIF4F Translation Initiation Complex- New Opportunities for Cancer Treatment

Helene Malka-Mahieu, Michelle Newman, Laurent Desaubry, et al.

Clin Cancer Res Published OnlineFirst October 27, 2016.

Updated version Access the most recent version of this article at: doi:10.1158/1078-0432.CCR-14-2362

Supplementary Access the most recent supplemental material at: Material http://clincancerres.aacrjournals.org/content/suppl/2016/10/27/1078-0432.CCR-14-2362.DC1

Author Author manuscripts have been peer reviewed and accepted for publication but have not yet been Manuscript edited.

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