Kinesin Eg5 Research Articles

Significant decrease of ADP release rate underlies the potent activity of dimethylenastron to inhibit mitotic kinesin Eg5 and cancer cell proliferation

Eg5 is a mitotic kinesin that plays a crucial role in the formation of bipolar mitotic spindles, by hydrolyzing ATP to push apart anti-parallel microtubules. Dimethylenastron is potent specific small molecule inhibitor of Eg5. The mechanism by which dimethylenastron inhibits Eg5 function remains unclear. By comparing with enastron, here we report that dimethylenastron prevents the growth of pancreatic and lung cancer cells more effectively, by halting mitotic progression and triggering apoptosis. We analyze their interactions with ADP-bound Eg5 crystal structure, and find that dimethylenastron binds Eg5 motor domain with higher affinity. In addition, dimethylenastron allosterically blocks the conformational change of the “sandwich”-like ADP-binding pocket more effectively. We subsequently use biochemical approach to reveal that dimethylenastron slows ADP release more significantly than enastron. These data thus provide biological, structural and mechanistic insights into the potent inhibitory activity of dimethylenastron.

Salt-inducible kinase 3 is a novel mitotic regulator and a target for enhancing antimitotic therapeutic-mediated cell death.

Many mitotic kinases are both critical for maintaining genome stability and are important targets for anticancer therapies. We provide evidence that SIK3 (salt-inducible kinase 3), an AMP-activated protein kinase-related kinase, is important for mitosis to occur properly in mammalian cells. Downregulation of SIK3 resulted in an extension of mitosis in both mouse and human cells but did not affect the DNA damage checkpoint. Time-lapse microscopy and other approaches indicated that mitotic exit but not mitotic entry was delayed. Although repression of SIK3 alone simply delayed mitotic exit, it was able to sensitize cells to various antimitotic chemicals. Both mitotic arrest and cell death caused by spindle poisons were enhanced after SIK3 depletion. Likewise, the antimitotic effects due to pharmacological inhibition of mitotic kinases including Aurora A, Aurora B, and polo-like kinase 1 were enhanced in the absence of SIK3. Finally, in addition to promoting the sensitivity of a small-molecule inhibitor of the mitotic kinesin Eg5, SIK3 depletion was able to overcome cells that developed drug resistance. These results establish the importance of SIK3 as a mitotic regulator and underscore the potential of SIK3 as a druggable antimitotic target.

The Kinesin-12 Kif15 is a processive track-switching tetramer

Kinesin-12 motors are a little studied branch of the kinesin superfamily with the human protein (Kif15) implicated in spindle mechanics and chromosome movement. In this study, we reconstitute full-length hKif15 and its microtubule-targeting factor hTpx2 in vitro to gain insight into the motors mode of operation. We reveal that hKif15 is a plus-end-directed processive homotetramer that can step against loads of up to 3.5 pN. We further show that hKif15 is the first kinesin that effectively switches microtubule tracks at intersections, enabling it to navigate microtubule networks, such as the spindle. hKif15 tetramers are also capable of cross-linking microtubules, but unexpectedly, this does not depend on hTpx2. Instead, we find that hTpx2 inhibits hKif15 stepping when microtubule-bound. Our data reveal that hKif15 is a second tetrameric spindle motor in addition to the kinesin-5 Eg5 and provides insight into the mechanisms by which hKif15 and its inhibitor hTpx2 modulate spindle microtubule architecture. DOI: http://dx.doi.org/10.7554/eLife.01724.001.

Terpendole E and its Derivative Inhibit STLC‐ and GSK‐1‐Resistant Eg5

Terpendole E is first natural product found to inhibit mitotic kinesin Eg5, but its inhibitory mechanism remains to be revealed. Here, we report the effects of terpendole E and 11ketopaspaline (a new natural terpendole E analogue) on the Eg5-microtubule interaction and in several Eg5 mutants. 11-Ketopaspaline is a shunt product from terpendole E, and it shows potent inhibitory activity against the microtubule-stimulated ATPase activity of Eg5. Unlike other Eg5 inhibitors, such as S-trityl-L-cysteine (STLC) and GSK-1, both terpendole E and 11-ketopaspaline only partially inhibited Eg5-microtubule interaction. Furthermore, terpendole E and 11-ketopaspaline inhibited several Eg5 mutants that are resistant to STLC (Eg5(D130A), Eg5(L214A)) or GSK-1 (Eg5(I299F), Eg5(A356T)), but with the same extent of inhibition against wild-type Eg5. Because Eg5(D130A) and Eg5(L214A) show cross-resistance to most known Eg5 inhibitors, which bind the L5 loop, these results suggest that terpendole E and its analogues have a different binding site and/or inhibitory mechanism to those for L5 loop-binding type Eg5 inhibitors.

Synthesis of Potential Pyrimidine Derivatives via Suzuki Cross-Coupling Reaction as HIV and Kinesin Eg5 Inhibitors

A series of 4-amino-5-((4-chlorophenyl)diazenyl)-6-(alkylamino)-1-methylpyrimidin-2-one deri- vatives 7–16 were prepared by nucleophilic displacement of 6-chloro-pyrimidine 6 by various amines. 4-Amino-5-((aryl-4-yl)diazenyl)-6-aryl-1-methylpyrimidin-2-one analogs 19–27, as well as 4-amino-5-((aryl-[1,1′-biphenyl]-4-yl)diazenyl)-6-aryl-1-methylpyrimidin-2-one 29–31 and 4-amino-6-aryl-1-methylpyrimidin-2-one 34–34, were synthesized via Suzuki cross-coupling reaction, using Pd(PPh3)4 as a catalyst and arylboronic acids as reagents. All compounds were evaluated for their antiviral activity against the replication of HIV-1 and HIV-2 in MT-4. Compounds 6, 16, 27, and 29 showed a 50% effective concentration of >2.15, >3.03, >2.29, and >1.63 μM, respectively, but no selectivity was observed (selectivity index < 1). Two of the newly synthesized pyrimidines 12 and 29 exhibited moderate kinesin Eg5 inhibition.

A Synthetic Lethal Interaction between APC/C and Topoisomerase Poisons Uncovered by Proteomic Screens

The Anaphase-promoting complex/cyclosome (APC/C) cofactor Cdh1 modulates cell proliferation by targeting multiple cell-cycle regulators for ubiquitin-dependent degradation. Lack of Cdh1 results in structural and numerical chromosome aberrations, a hallmark of genomic instability. By using a proteomic approach in Cdh1-null cells and mouse tissues, we have identified kinesin Eg5 and topoisomerase 2α as Cdh1 targets involved in the maintenance of genomic stability. These proteins are ubiquitinated and degraded through specific KEN and D boxes in a Cdh1-dependent manner. Whereas Cdh1-null cells display partial resistance to Eg5 inhibitors such as monastrol, lack of Cdh1 results in a dramatic sensitivity to Top2α poisons as a consequence of increased levels of trapped Top2α-DNA complexes. Chemical inhibition of the APC/C in cancer cells results in increased sensitivity to Top2α poisons. This work identifies invivo targets of the mammalian APC/C-Cdh1 complex and reveals synthetic lethal interactions of relevance in anticancer treatments.

Intracellular delivery of functionally active proteins using self-assembling pyridylthiourea-polyethylenimine

Intracellular delivery of functionally active proteins into cells is emerging as a novel strategy for research and therapeutic applications. Here, we present the properties of a self-assembling pyridylthiourea-modified polyethylenimine (πPEI), which interacts with proteins and promotes their delivery into the cytosol of mammalian cells. In aqueous medium at pH7.4, self-association of πPEI in the presence of green fluorescent proteins (GFP) leads to supramolecular protein-entrapped assemblies. These assemblies protect GFP from losing its fluorescence upon pH variation and assist delivery/translocation into the cytosol of mammalian cells via the endocytic pathway. The scope of application of this delivery system was extended to antibodies against intracellular targets as illustrated using a monoclonal antibody directed against the HPV-16 viral E6 oncoprotein and an antibody directed against the threonine-927 phosporylation site of the EG5 kinesin spindle protein. The πPEI-mediated delivery of native anti-E6 antibodies or anti-E6 antibodies equipped with a nuclear localization signal (NLS), led to regeneration of the p53 tumor suppression protein in E6-transformed CaSki cells. Delivery of functionally active anti-EG5 antibodies, with the same polymer, reduced HeLa cell viability and appeared to perturb, as expected, chromosome segregation during mitosis. Altogether, these results provide an easy to use delivery system for extending the scope of application of antibodies for epitope recognition within living cells and may provide novel opportunities for selective interference of cell function by a steric hindrance modality.

Photocontrol of the mitotic kinesin Eg5 using a novel S-trityl-L-cysteine analogue as a photochromic inhibitor

Because the mitotic kinesin Eg5 is essential for the formation of bipolar spindles during eukaryotic cell division, it has been considered as a potential target for cancer treatment. A number of specific and potent inhibitors of Eg5 are known. S-trityl-L-cysteine is one of the inhibitors of Eg5 whose molecular mechanism of inhibition was well studied. The trityl group of S-trityl-L-cysteine was shown to be a key moiety required for potent inhibition. In this study, we synthesized a novel photochromic S-trityl-L-cysteine analogue, 4-(N-(2-(N-acetylcysteine-S-yl) acetyl) amino)-4'- (N-(2-(N-(triphenylmethyl)amino)acetyl)amino)azobenzene (ACTAB), composed of a trityl group, azobenzene and N-acetyl-L-cysteine, which exhibits cis-trans photoisomerization in order to photocontrol the function of Eg5. ACTAB exhibited cis-trans photoisomerization upon alternating irradiation at two different wavelengths in the visible range, 400 and 480 nm. ACTAB induced reversible changes in the inhibitory activity of ATPase and motor activities correlating with the cis-trans photoisomerization. Compared with cis-ACTAB, trans-ACTAB reduced ATPase activity and microtubule gliding velocity more significantly. These results suggest that ACTAB could be used as photochromic inhibitor of Eg5 to achieve photocontrol of living cells.

Synthesis, Antiviral and Kinesin Eg5 Activities of New Indomethacin Analogues

Aim: Synthesis, characterization, anti-HIV, anti-HCV and kinesin activities of new indomethacin analogues have been carried out. Methodology: Arylated derivatives of indomethacin via the Suzuki-Miyaura crosscoupling reaction using palladium acetate/triphenylphophineor palladium based Nheterocyclic carbene (Pd-NHC) complexe as catalysts were synthesized and characterized by the H and C and 2D NMR study. Analogously, indomethacin analogues bearing thioureido and amide moieties of various L-amino acid esters were prepared via Kabbani and coupling reactions, respectively. Results: All the new analogues were evaluated In vitro for their antiviral activity against the replication of HIV-1 and HIV-2 in MT-4 cells using MTT assay. Compounds 28, 31 and 32 were evaluated In vitro for their inhibitory activity against hepatitis virus C (HCV) in the Huh 5-2 replicon system (type 1b, Con1 strain). Additionally, some analogues were screened for their inhibitory activity against the ATPase enzyme and the motor-protein Kinesin Eg5.In conclusion, Compounds 31 and 39 showed anti-HIV activity with IC50 values of >1.81 and > 3.21μM (CC50 of 3.31 and 28.89μM), resulting in selectivity indexs (SI) of 6 and 9, respectively. Conclusion: Compounds 31 and 39 displayed better anti-HIV activity than the other derivatives (SI = 6 and 9, respectively). Compound 27 showed ATPase inhibition value of 48% at 100 μM concentration. Original Research Article American Chemical Science Journal, 4(4): 516-536, 2014 517

Photo-Reversible Inhibition of Mitotic Kinesin Eg5 by Photochromic STLC Analogues Composed of Azobenzene

The kinesin Eg5, is a microtubule plus-end directed homotetrameric molecular motor that is essential for the formation of a bipolar spindle during eukaryotic cell division. Eg5 exists only in proliferating cells, and is required for mitosis. Therefore, Eg5 is new target of cancer therapy. It is known that some small molecules specifically inhibit Eg5 activity. S-trityl-L-cysteine (STLC) is one of the potent Eg5 specific inhibitors. In this study, we tried to develop photochromic Eg5 inhibitors that control inhibitory activity of Eg5 by ultraviolet (UV) and visible (VIS) light irradiations reversibly. Azobenzene is one of the typical photochromic molecules, which shows cis, and trans isomerization by UV and VIS light irradiations respectively. In this study, we designed and synthesized photochromic inhibitors utilizing azobenzene. As the trityl group of STLC is a key moiety to exhibit inhibitory activity, we linked the trityl group to N-acetyl cysteine or maleic acid via azobenzene. The synthesized two photochromic inhibitors, TAB-MA and TAB-Ac-Cys inhibited the ATPase activity of Eg5 at the different inhibition constants between cis and trans isomers. Trans-isomers of the inhibitors showed more significant inhibition of ATPase activity than cis-isomers. Moreover, Eg5 driven microtubule gliding was photo controlled by TAB-Ac-Cys. Trans-TAB-Ac-Cys decreased the velocity of microtubule gliding more significantly than cis-TAB-Ac-Cys.

Photocontrol of Mitotic Kinesin Eg5 by Incorporating of Photochromic Molecule into the Functional Loop L5

All member of kinesin superfamily contain a structurally conserved loop L5 near the ATP binding site. The length of the L5 vary among kinesin superfamily members. It is believed that L5 of kinesin is important region for motor function. Interestingly mitotic kinesin Eg5 has the longest L5 in comparing with other kinesins. The kinesin Eg5 is a microtubule plus-end directed homotetrameric molecular motor that is essential for the formation of a bipolar spindle during eukaryotic cell division. It has been demonstrated that L5 of Eg5 performed as a stabilizer for the Eg5-specific inhibitors (STLC, monastrol) complexes. These inhibitors bind to the same pocket on the Eg5 motor domain composed by of loop L5, α2 and α3. In this study, we tried to photo control of Eg5 ATPase activity by incorporating of photochromic molecule into L5. We prepared 5 mutants of Eg5 which have a single cysteine in L5 in order to incorporate thiol-reactive photochromic molecules. We also synthesized thiol-reactive azobenzene derivative, iodoacetyl-trity-azobenzene (IATAB) and spiropyran derivative, iodoacetyl-spiropyran (IASP). Azobenzene is photoisomerized to trans form of hydrophobic by visible light irradiation, and to cis form of hydrophilic by UV light irradiation. Spiropyran is photoisomerized to zwitterionized merocyanine by UV light irradiation. Merocyanine is converted to hydrophobic spiropyran by visible light irradiation. Photochromic molecules were incorporated into the mutants stoichiometrically. The Eg5 mutant W127C and D130C modified with IASP showed reversible alteration of microtubule dependent ATPase activity upon UV and visible light irradiations. In addition, we also succeed in photo control of inhibitory effect of IASP-W127C and IASP-D130C by STLC.

Photo-Regulation of Kinesin Eg5 ATPase and Motor Activity using Novel Photochromic Inhibitor Composed of Spiropyran and Cysteine

The mitotic kinesin Eg5 has an important role in establishing the bipolar spindle which is directly involved in the cell division. Recently, several small molecules have been identified as potent specific inhibitor of Eg5. STLC is one of the inhibitor which does not compete with either ATP or microtubules but slows down ADP release. STLC binds to the pocket on Eg5 composed by a2, a3 and loop L5. STLC binding induces the downward swing of L5 to close the inhibitor binding pocket. Therefore, L5 is one of the key region to stabilize Eg5-STLC complex.

3P155 有糸分裂キネシンEg5 の新規SH 基反応性フォトクロミック分子を用いた光制御(分子モーター,ポスター,第52回日本生物物理学会年会(2014年度))

3P155 有糸分裂キネシンEg5 の新規SH 基反応性フォトクロミック分子を用いた光制御(分子モーター,ポスター,第52回日本生物物理学会年会(2014年度))

1P189 Examining mitotic functions of bipolar kinesin Eg5 in a reconstituted minimal microtubule network(12. Cell biology,Poster,The 52nd Annual Meeting of the Biophysical Society of Japan(BSJ2014))

1P189 Examining mitotic functions of bipolar kinesin Eg5 in a reconstituted minimal microtubule network(12. Cell biology,Poster,The 52nd Annual Meeting of the Biophysical Society of Japan(BSJ2014))

Structural Kinetics of the Mitotic Kinesin Eg5

Members of the kinesin superfamily of molecular motors differ in several key structural domains, which probably allow these molecular motors to serve the different physiologies required of them. One of the most variable of these is a stem-loop motif referred to as L5. This loop is longest in the mitotic kinesin Eg5, and previous structural studies have shown that it can assume different conformations in different nucleotide states. However enzymatic domains often consist of a mixture of conformations whose distribution shifts in response to substrate binding or product release, and this information is not available from the

Developmental expression and role of Kinesin Eg5 during Xenopus laevis embryogenesis

The neural crest is a transient multipotent migratory cell population unique to vertebrates. These cells undergo an epithelial-to-mesenchymal transition and migrate extensively through the embryo. They differentiate into numerous diverse derivatives including the peripheral nervous system, melanocytes,and craniofacial cartilages. The development of the neural crest is mediated by complex interactions of multiple signals and transcription factors. The kinesin Eg5 is a plus end-directed microtubule-based motor protein that is essential for bipolar spindle formation during mitosis and meiosis, axon growth, and mammal embryonic development. We analyzed in detail the expression pattern of eg5 and established that it is expressed at the prospective neural fold, in the premigratory and migratory neural crest. Functional analysis revealed that in Xenopus, early embryogenesis eg5 function is required during neural crest induction, specification, and maintenance. eg5 is also required during neural crest migration and for derivatives formation. Moreover, we demonstrated a hierarchical relationship with the Indian Hedgehog signaling pathway. Our results show that eg5 is essential for the specification and maintenance of neural crest progenitors during Xenopus early embryogenesis rather than cell proliferation and survival.

Photocontrol of mitotic kinesin Eg5 facilitated by thiol-reactive photochromic molecules incorporated into the loop L5 functional loop

Kinesin Eg5 is a plus-end-directed microtubule-based motor that is essential for bipolar spindle formation during eukaryotic cell division. Loop L5 of mitotic kinesin Eg5 is a key region determining ATPase activity and motor function. Photochromic molecules undergo reversible isomerization in response to ultraviolet and visible light irradiation. We introduced three kinds of photochromic molecules, 4-phenylazomaleinanil (PAM), 4-(N-(2-iodoacetyl)amino)-4'-(N-(2-(N-(triphenylmethyl)amino)acetyl)amino)azobenzene (IATAB) and 3,3-dimethyl-1-(2-(2-iodoacetoxy)ethyl)-3H-1,2-dihydroindole-2-spiro-2'-(2H)-6'-nitrochromene (IASP) into L5 to control the Eg5 ATPase activity using light irradiation. We prepared five kinesin Eg5 motor domain mutants, E116C, E118C, Y125C, W127C and D130C, which contained a single reactive cysteine residue in loop L5. The ability of S-trityl-l-cysteine (STLC), a specific Eg5 inhibitor, to inhibit E116C, W127C and D130C was significantly reduced. The photochromic molecules were stoichiometrically incorporated into the cysteine residues in L5 of mutants. W127C and D130C modified with IASP exhibited reversible ATPase activity alterations when subjected to light irradiation-induced photoisomerization. The two IASP modified mutants also demonstrated photocontrolled alterations following treatment with STLC. Additionally, the ATPase activity of the mutant D130C modified with PAM could be photocontrolled. Our findings demonstrate that incorporation of photochromic molecules into the key region of loop L5 facilitates the photocontrol of the function of kinesin Eg5.

Abstract C55: Discovery and optimization of inhibitors of the KIFC1 motor protein.

Abstract KIFC1, a kinesin-14 family protein, plays an essential role in centrosomal bundling, a strategy employed by cancer cells to avoid multipolar mitosis in the presence of amplified centrosomes. However, its function is not required for normal diploid cell division, suggesting that KIFC1 is an attractive therapeutic target for human cancers. We have recently reported the first small molecule inhibitor of KIFC1, AZ82 [1]. AZ82 binds specifically to the KIFC1/microtubule (MT) binary complex, and inhibits the MT-stimulated KIFC1 enzymatic activity with a KI of 0.043 µM. AZ82 effectively engaged with the minus-end directed KIFC1 motor in HeLa cells to reverse the monopolar spindle phenotype induced by the inhibition of the plus end-directed kinesin Eg5 by AZD4877, consistent with what was observed with genetic knock down of KiFC1 by siRNA. Additionally, treatment with AZ82 caused centrosome declustering in BT-549 breast cancer cells with amplified centrosomes. Here we further describe the chemistry approach and related structure-activity relationships that led to the discovery of AZ82. [1] http://pubs.acs.org/doi/abs/10.1021/cb400186w Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C55. Citation Format: Michelle L. Lamb, Jiaquan Wu, Keith Mikule, Wendy Wang, Nancy Su, Philip Petteruti, Farzin Gharahdaghi, Erin Code, Xiahui Zhu, Kelly Jacques, Zhongwu Lai, Tao Zhang, David Boulay, Gurmit Grewal, Nicholas Keen, Bin Yang, Claudio Chuaqui, Claudio Chuaqui, Huawei Chen. Discovery and optimization of inhibitors of the KIFC1 motor protein. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C55.

Loop L5 Assumes Three Distinct Orientations during the ATPase Cycle of the Mitotic Kinesin Eg5: A TRANSIENT AND TIME-RESOLVED FLUORESCENCE STUDY

Members of the kinesin superfamily of molecular motors differ in several key structural domains, which probably allows these molecular motors to serve the different physiologies required of them. One of the most variable of these is a stem-loop motif referred to as L5. This loop is longest in the mitotic kinesin Eg5, and previous structural studies have shown that it can assume different conformations in different nucleotide states. However, enzymatic domains often consist of a mixture of conformations whose distribution shifts in response to substrate binding or product release, and this information is not available from the "static" images that structural studies provide. We have addressed this issue in the case of Eg5 by attaching a fluorescent probe to L5 and examining its fluorescence, using both steady state and time-resolved methods. This reveals that L5 assumes an equilibrium mixture of three orientations that differ in their local environment and segmental mobility. Combining these studies with transient state kinetics demonstrates that there is a major shift in this distribution during transitions that interconvert weak and strong microtubule binding states. Finally, in conjunction with previous cryo-EM reconstructions of Eg5·microtubule complexes, these fluorescence studies suggest a model in which L5 regulates both nucleotide and microtubule binding through a set of reversible interactions with helix α3. We propose that these features facilitate the production of sustained opposing force by Eg5, which underlies its role in supporting formation of a bipolar spindle in mitosis.

Abstract A297: Microtubule targeting antimitotic drugs induce a lower mitotic arrest than clinically less effective antimitotic Eg5 inhibitors in mouse xenografts.

Abstract Despite immense progress in targeted cancer drug design, to date, the most important drugs in chemotherapy remain traditional cytotoxic drugs which are thought to kill proliferating cells, no matter if malignant of not. This "antiproliferative" hypothesis is based on results from the 1970s coming from mouse leukemia models or cell culture experiments. Microtubule binding drugs are clinically important antiproliferative drugs which arrest cultured cancer cells in mitosis. As opposed to empirically found microtubule binding drugs, newer drugs designed from scratch to induce mitotic arrest have repeatedly failed in clinical trials, suggesting that the antitumor effect of microtubule binding drugs is still not well understood. Alas, tissue culture assays are not predictive of their respective clinical success, suggesting that more realistic models are needed to understand why there are such huge differences in antitumor efficacy. Therefore, in this project, we used in vivo microscopy of mouse xenografts to compare the cell cycle effects of microtubule drugs to those of newer, targeted antimitotic drugs in the form of inhibitors of the mitotic kinesin Eg5. Image analysis with a custom developed software for automated three dimensional segmentation and cell cycle classification revealed that the microtubule interacting drugs Paclitaxel and Eribulin which are in wide clinical use induce a much lower mitotic arrest than the Eg5 inhibitor Ispinesib which failed clinical trials. This suggests that, rather than mitotic arrest, a different mechanism, intrinsically coupled to microtubule binding, might be essential for the antitumor effect of microtubule drugs in vivo. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A297. Citation Format: Stefan Florian, Deepak R. Chittajallu, Rainer H. Kohler, James D. Orth, Peter K. Sorger, Ralph Weissleder, Gaudenz Danuser, Timothy J. Mitchison. Microtubule targeting antimitotic drugs induce a lower mitotic arrest than clinically less effective antimitotic Eg5 inhibitors in mouse xenografts. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A297.