bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract C43: Dasatinib resensitizes Kras mutant colorectal tumors to cetuximab
Authors: Dunn Emily F. , Iida Mari , Armstrong Eric , Wheeler Deric L. 
Published: June 2012

Abstract
Several recent clinical trials have demonstrated a strong correlation between Kras mutational status and resistance to cetuximab in metastatic colorectal cancer (mCRC). The work presented here sought to further understand the resistance of Kras mutant tumors to cetuximab and analyze dasatinib, a potent FDA approved SRC family kinase inhibitor, and its ability to overcome cetuximab resistance in this genetic setting. We analyzed 16 CRC lines for cetuximab growth response in vivo, expression of EGFR, SRC, and Kras mutational status. From this analysis we selected three Kras mutant lines (HCT116, LS180, LoVo), one Kras wild type line (SW48), and one EGFR negative line (Colo320DM) for further studies. Approximately two million cells from each line were inoculated in the dorsal flanks of athymic nude mice and allowed to grow to 100mm cubed. At that time mice were given 0.3mg of cetuximab twice weekly for 2 to 4 weeks. All Kras mutant lines were resistant to cetuximab in vivo, whereas the Kras wild type line showed significant tumor growth inhibition to cetuximab therapy. Each Kras mutant line was then analyzed for response to dasatinib alone. Mice were given 30mg/kg of dasatinib fives times weekly by oral gavage for 2 to 4 weeks. Results of these experiments indicated that Kras mutant tumors exhibited very little response to dasatinib monotherapy. However, dasatinib given in combination with cetuximab lead to significant tumor growth delay relative to vehicle controls. Collectively, these data suggest that Src and its family of kinases cooperate with the EGFR in the Kras mutant, mCRC setting and dual blockade has a distinct anti-tumor effect. These studies strengthen the rationale for the design of clinical trials combining dasatinib and cetuximab in the Kras mutant mCRC setting.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C43.
Abstract C54: In silico docking of the human cancer proteome in search of multitarget cancer therapeutics
Authors: Meroueh Samy , Li Liwei , Bum-Erdene Khuchtumur 
Published: June 2012

Abstract
A recent effort at uncovering the genome of various cancers has found multiple mutations across the genome of these cells reinforcing the view that cancer is a systems biology disease. The development of effective cancer therapeutics will require shifting the current paradigm from targeting individual proteins to instead targeting the broader signaling pathways. Towards that end, we have initiated an effort to employ in silico docking to screen against a large set of protein structures from the human proteome that have been implicated in cancer. We consider two datasets of proteins in our effort. First, a recently established dataset known as the Human Cancer Proteome Interaction Network (HCPIN) provides a set of structures corresponding to oncogenes as well as proteins that associate with them. Second, we created the human druggable protein (HDP) dataset that consists of targets of FDA-approved drugs. The surface of these 1,589 proteins was mapped for binding cavities that can accommodate a small molecule. We found more than 1,900 cavities spanning these proteins. We then prepared each of these binding cavities for in silico docking of 1,600 molecules from the NCI diversity set. The resulting 3,000,000 complexes were scored with multiple scoring functions to enable the ranking of molecules for each cavity. In an initial effort to identify anti-cancer therapeutics, we employed a combination of machine learning and fingerprint analysis to seek molecules whose binding profile would mimic the clinically used drug erlotinib. Among a set of 12 molecules that were selected, we found that four inhibited H1299 and H460 tumor cell growth in cell culture-based assays, with one molecule exhibiting an IC50 in the low micromolar region. We performed an assessment of the pharmacokinetic properties of these compounds to assess their suitability as potential leads for drug development.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C54.
Abstract C55: Efficacy of PI3K inhibitors to cancer cells with PIK3CA mutation or loss of PTEN expression
Authors: Dan Shingo , Sugita Hironobu , Seki Mariko , Mukai Yumiko , Yamazaki Kanami , Ishikawa Yuichi , Yamori Takao 
Published: June 2012

Abstract
Phosphoinositide 3-kinase (PI3K) pathway is frequently activated in cancer and is thought to be a promising therapeutic target. We previously reported a specific PI3K inhibitor ZSTK474 having a potent antitumor activity in vitro and in vivo without severe toxicity. Since then, diverse PI3K inhibitors have been developed, and some of them already entered clinical trials. Gain-of-function mutations of PIK3CA and loss of PTEN expression are frequently observed in various cancers and believed to activate PI3K-downstream effectors, but it is not well understood whether PI3K inhibitors have therapeutic efficacies against such cancers. In this study, taking advantage of pharmacologically well-characterized 39 human cancer cell lines (JFCR39), we examined the efficacies of eleven PI3K inhibitors including ZSTK474 and NVP-BEZ235, the mutational status and the protein expression levels of PIK3CA (p110) and PTEN in each of the cell lines. As a result, we found eight cell lines carrying missense mutations in PIK3CA. Most mutations were located in hotspot (E545K and H1047R), but some of them were in other residues. We evaluated kinase activities of these mutants and found that four of them including P449T (2.3-fold), E545K (8.5-fold), E545K/D549N (6.3-fold) and H1047R (5.8-fold) exhibited enhanced kinase activities compared to wild-type p110 , and seven of 39 cell lines had such mutation. On the other hand, mutational analysis of PTEN revealed that nine cell lines had missense mutation or deletion in PTEN, and seven of them did not express PTEN protein. Then, we compared the efficacies of PI3K inhibitors in cell lines with gain-of-function mutation of PIK3CA or loss of PTEN expression with those in other cell lines, and no significant correlation was observed. We further examined the inhibitory effect of three PI3K inhibitors on the enzymatic activity of p110 mutants, and all of three inhibited the kinase activity of E545K and H1047R mutant as well as wild-type p110 . These results suggested that PI3K inhibitors examined in this study were effective to cancer cells with PIK3CA mutation or PTEN loss equivalent to those having normal PIK3CA and PTEN expression, and that these PI3K inhibitors are applicable in clinical use for treatment of such cancers.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C55.
Abstract C59: Discovery and characterization of selective PI3Kα and PI3Kα/mTOR-dual inhibitors for targeting PI3Kα-activated tumors
Authors: Foster Paul G. 
Published: June 2012

Abstract
Background: The PI3K pathway regulates cell growth, proliferation and survival, and is dysregulated with high frequency in human tumors. PI3K pathway activation in tumors occurs via multiple mechanisms including prevalent mutation and amplification of the PIK3CA gene (which encodes the p110 subunit of PI3Kα). Downregulation of the lipid phosphatase PTEN also activates PI3K pathway signaling in a subset of tumors, via a mechanism reported to be PI3Kβ dependent. These findings suggest that isoformselective PI3K inhibitors may have utility in distinct, genetically defined tumor populations. Downstream of PI3K, mTOR controls cell growth and proliferation through its two distinct signaling complexes: mTORC1 and mTORC2. We report on the discovery of PI3Kα and dual PI3Kα/mTOR-selective inhibitors intended to target tumors harboring activating mutations or amplifications in PIK3CA.
Methods: We identified and optimized a series of PI3Kα and PI3Kα/mTOR inhibitors through high-throughput screening and medicinal chemistry techniques. Biochemical assays employed recombinant class 1 PI3K and mTOR proteins and cellular assays employed ELISA or western blot assays to monitor PI3K pathway signaling.
Results: We have identified potent (biochemical IC50s &lt; 20 nM), ATP-competitive inhibitors of PI3Kα or PI3Kα and mTOR with excellent selectivity over other PI3K isoforms and a diverse panel of protein kinases. Cellular assays in the PI3Kα-activated MCF7 cell line demonstrate that these compounds inhibit phosphorylation of targets downstream of both PI3K (Akt) and mTOR (S6 and p70S6 kinase), and also inhibit tumor cell proliferation. However, in PC3 tumor cells lacking PTEN, effects on PI3K pathway readouts are less evident. In vivo pharmacodynamic analyses following oral administration of PI3Kα/mTOR inhibitors to mice bearing xenograft tumors demonstrate dose-dependent inhibition of phosphorylation of both PI3K and mTOR effectors at well-tolerated doses.
Conclusions: PI3Kα and PI3Kα/mTOR-selective small molecule inhibitors were discovered that demonstrate potent in vitro and cellular activity and good oral bioavailability. Cellular selectivity for PI3Kα mutant tumor cells versus PTEN deleted tumor cells was demonstrated. These compounds will allow an exploration of the efficacy and tolerability of selective PI3Kα and PI3Kα/mTOR inhibitors in preclinical tumor models.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C59.
Abstract C7: Sensitization of human colorectal cancer cells to TRAIL induced-apoptosis following inhibition of PI3K or HSP90
Authors: Saturno Grazia , Clarke Paul A. , Workman Paul 
Published: June 2012

Abstract
TRAIL (Tumor-Necrosis-Factor related apoptosis-inducing ligand) induces apoptosis by binding to the death receptors DR4 and DR5. Recombinant TRAIL or agonist antibodies against TRAIL death-receptors are now in Phase I/II clinical trials. Despite specificity for cancer cells, a percentage of tumor cells remain insensitive to TRAIL-induced apoptosis. Previous work has demonstrated that signaling through PI3K (phosphatidylinositol-3-kinase) can prevent TRAIL-induced apoptosis in different cancer cell types. Moreover, inhibition of HSP90 (Heat Shock Protein 90) by 17-AAG can sensitize colon cancer cells to TRAIL-induced apoptosis. The aim of this project is to explore the mechanism of TRAIL resistance and to focus on the role of PI3K and HSP90 signaling and the ability of PI3K or HSP90 inhibitors to reverse resistance to TRAIL-induced apoptosis in human colorectal cancer cells. We demonstrated that co-treatments with TRAIL and PI-103, a PI3K inhibitor, or 17-AAG, an HSP90 inhibitor, synergistically contributed to the apoptotic stimulus in TRAIL sensitive and resistant colorectal cancer cells through the amplification of both extrinsic and intrinsic apoptotic pathways; this effect was lower or not present in non-tumor cells, suggesting a therapeutic index. These data support the potential use of TRAIL in combination with PI3K or HSP90 inhibitors in patients with colorectal cancer who showed no response to the ligand alone.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C7.
Abstract C82: The role of the neuregulin family in the nucleus
Authors: Wang Ming 
Published: June 2012

Abstract
The neuregulin family consists of four members, NRG1- 4 each of which plays an important role in several normal physiological processes including tumorigenesis. We have focused on the 3 isoform of NRG1 which was found to localise to two subnuclear compartments: nucleoli and spliceosomes. We hypothesised that such localisation may have specific functions in modifying cell behaviour.
Methods: To examine whether nuclear accumulation of NRG1 occurs in other physiological conditions besides in ductal carcinomas of the breast, we immunohistochemically stained a range of normal and cancer tissues with antibodies to NRG1α or NRG1β. Second, Based on the previous observation that NRG1 3 localisation could change from the nucleolar pattern to the speckle pattern or vice versa, we monitored the trafficking of photoactivatable green fluorescent protein (PAGFP) tagged NRG1β3 in live cells using confocal fluorescence microscopy. We also explored the expression patterns of ErbB3 when co-expressed with NRG1β3 by immunofluorescence microscopy. To test the hypothesis whether nuclear targeting of NRG1β3 could be involved in stimulating cell mitogenesis we performed a Bromodeoxyuridine (BrdU) assay on cells transfected with NRG1β3 constructs.
Results: Nuclear expression of NRG1α and NRG1β was found in normal skin, adrenal and thyroid tissues and in various cancers. In general, NRG1α has a higher frequency of nuclear expression than NRG1β. By monitoring the PAGFP tagged NRG1β3 in live cells we observed that NRG1β3 moved from nucleoli to spliceosomes. As a cognate receptor of NRG1, ErbB3 was not colocalised with NRG1β3 in the nucleus. With respect to possible functions of intranuclear NRG1, the BrdU assay results showed that wildtype NRG1β3 and the mutant which lost the ability to target to nucleoli had no obvious effect on DNA synthesis.
Conclusion: Detection of nuclear expression of NRG1 in a range of normal and cancer tissues using immunohistochemical staining provides a physiological basis for further studies at the molecular level. The receptor-independent nuclear localisation of NRG1β3 suggests it may be participating in a novel-signalling pathway. Moreover, its association with nucleoli and spliceosomes, two nuclear compartments involved in ribosome synthesis and RNA splicing supports the hypothesis that nuclear NRG may have highly specific functions in defined nuclear compartments.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C82.
Abstract C89: Rac1 splicing variant Rac1b: Towards isoform selective inhibitors for the treatment of cancer
Authors: Laurent Desire , Casagrande Anne-Sophie , Leblond Bertrand , Beausoleil Eric , Taverne Thierry , Chauvignac Cedric , Pando Matt 
Published: June 2012

Abstract
The pivotal role of Rac1, a member of the Rho family of small GTPases, has been well characterized in the genesis of many cancers. The aberrant activation of Rac1 promotes uncontrolled proliferation, invasion and metastatic properties of human cancer cells.
Via ExonHit Therapeutics' alternative splicing discovery plateform DATAS™, we identified a repertoire of genes deregulated in cancer. Among them, Rac1b, an alternative splice variant of Rac1, was found deregulated and overexpressed in diverse cancer types, including breast and colon. Rac1b is constitutively active and transforming, and since it was shown to sustain cancer cell survival, such as for colorectal cancer cells, there is considerable interest in the development of small molecule inhibitors of Rac1/Rac1b.
We previously synthesized and fully characterized EHT 1864 as a pharmacological tool to study Rac1 functions(Shutes A et al. (2007). J Biol Chem. 282(49):35666-78). Then, using molecular docking algorithms and ExonHit's screening platform for nucleotide binding inhibitors, novel compounds were synthesized and characterized for Rac1/Rac1b inhibition and Rac1 versus Rac1b selectivity.
Here, we describe new Rac1/Rac1b inhibitors with better pharmacological profile than EHT 1864 and better potency in various in vitro cancer cell models. Some of these pharmacological tools are good candidates for subsequent in vivo cancer studies to study Rac1 and Rac1b mediated cellular functions and to modulate pathological conditions in which Rac1 or Rac1b deregulation may play a role.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C89.
Abstract C93: Novel monosubstituted oxaliplatin analogs with improved characteristics
Authors: Jungwirth Ute , Heffeter Petra , Gojo Johannes , Abramkin Sergey , Meelich Kristof , Galanski Michael , Körner Wilfried , Micksche Michael M. , Keppler Bernhard K. , Berger Walter 
Published: June 2012

Abstract
Background: Oxaliplatin has unique activity against colon cancer cells distinctly different from cisplatin. Aim of this study was to determine the anticancer properties of new mono-substituted oxaliplatin analogs, namely KP1537 and KP1691, to define the underlying cellular and molecular mechanisms.
Methods: Cytotoxic/antiproliferative effects were tested against selected human cancer cell lines by MTT analysis. The impact of the DNA damage response pathway on the drug activities were determined using HCT-116 human colon carcinoma cells together with p53 or p21/WAF1 deleted sublines. Furthermore, DNA damage, cell cycle distribution and induction of apoptosis were analysed by Western Blotting, FACS analysis and immunofluorescence. Platinum accumulation was determined by ICP-MS. For in vivo toxicity experiments, mice were treated with KP1691 and oxaliplatin.
Results: Both oxaliplatin analogues had IC50 values in the low µM range, with those for KP1691 being significantly lower in comparison to oxaliplatin. Additionally, KP1691 was less affected by the p53 status of the cells as compared to oxaliplatin. The new compounds were more rapidly taken up by the tumor cells and accumulated over time to higher intracellular concentrations as compared to oxaliplatin. In HCT-116 cells all platinum drugs inhibited the DNA synthesis in a p53-dependent manner, associated with a distinct induction of p53 and p21 in the HCT-116 p53 cell model. This suggests that inhibition of DNA replication due to platinum adducts leads to a p53-dependent cell cycle arrest. KP1537 and KP1691 induced potent G1/S and G2/M arrests in parental HCT-116. While at wild-type p53 conditions the platinum drugs resulted in almost complete loss of S-phase, this fraction was widely unchanged in the p53- deleted subline. Accordingly, expression of cellcycle related genes including cyclin A, cyclin B1, and CDK1 were down-regulated in a p53-dependent manner. Platinum drug-induced DNA damage was confirmed by the phosphorylation of H2AX. First in vivo toxicity experiments in mice indicated significantly less side effects (weight loss) after KP1691 than after oxaliplatin treatment.
Conclusion: Taken together, these findings suggest that KP1537 and KP1691 have promising anticancer properties in vitro. Several aspects, including the lower IC50 values, higher accumulation rates and less side effects of KP1537 and KP1691 as compared to the parental compound oxaliplatin, suggest them for further (pre-) clinical development.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C93.
Abstract C96: The effect of non-steroidal anti-inflammatory drugs (NSAIDs) in ovarian cancer cells
Authors: Valle Blanca L. , D'Souza Theresa , Becker Kevin G. , Wood William H. , Wersto Robert P. , Morin Patrice J. 
Published: June 2012

Abstract
Epidemiological and laboratory studies have suggested a protective role for non-steroidal anti-inflammatory drugs (NSAIDs) against various neoplasms, including ovarian cancer. In an attempt to clarify the mechanisms and molecular targets of tumor prevention by NSAIDs, we have studied the effects of multiple NSAIDs in several ovarian cancer cell lines. NSAID treatment decreased the viability of all the ovarian cancer cell lines examined. To determine the effect of NSAIDs on the cell cycle, flow cytometry analysis was performed. Cells treated with indomethacin, ibuprofen or celecoxib were arrested in G1 phase, while cells treated with diclofenac underwent an S/G2 arrest. In addition, induction of apoptosis was cell line specific. The levels of several cell cycle regulatory and apoptosis proteins were examined. The levels of phosphorylated Rb protein decreased and phospho-p53 increased upon treatment with NSAIDs, suggesting an involvement of these proteins in the response of ovarian cancer cells to NSAID treatment. In order to further clarify the mechanisms of action of NSAIDs in ovarian cancer cells, gene expression profiling experiments were performed. Ovarian cancer cell lines Hey, OVCAR5, and UCI101 were treated with diclofenac, indomethacin, celecoxib, and ibuprofen, and microarray analysis was performed. A large number of gene expression changes were observed in the different cell lines treated with various NSAIDs. Among the most consistent and reproducible changes observed, S-phase kinase associated protein 2 (Skp2) was found to be downregulated at the mRNA and protein levels in all cell lines with all NSAIDs tested. In addition, Damage inducible transcript-4 (DDIT4) was found to be upregulated in all cell lines upon treatment with diclofenac, indomethacin and celecoxib. Skp2 forms part of the SCF ubiquitin ligase and is involved in the targeting for degradation of several proteins, including the cyclin dependent kinase inhibitors p21 and p27, therefore facilitating S-phase entry. DDIT-4, is transcriptionally activated upon p53 activation and it is known to inhibit mTOR signaling. In conclusion, we have identified a number of target genes that may be important for the NSAID-induced cell cycle arrest and apoptosis and their exact roles are currently being investigated.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C96.
Abstract PR-10: RNAi-directed identification of chemosensitizers of GSK923295 response
Authors: Yin Holly , Kiefer Jeff , Chow Donald , Que Quick Q. , Dastrup Erica , Weber Barbara , Wooster Richard , Mousses Spyro 
Published: June 2012

Abstract
Centromere-associated protein E (CENP-E) is a kinesin-like motor protein that plays a central role in chromosome segregation and control of cell division. GSK923295 (GSK295) is a potent and selective small-molecule inhibitor of human CENP-E ATPase activity, and has demonstrated broadspectrum activity in vivo against human tumor xenografts. GSK295 is currently being evaluated as a novel anticancer drug in Phase I clinical trials. RNAi phenotype profiling in the Druggable Genome was applied to discover specific genes that regulate GSK295 sensitivity. This study focused on nonsmall cell lung carcinoma (NSCLC) with three cell lines evaluated for HT-RNAi drug sensitivity analysis. A robust HT-RNAi cell-screening assay for GSK295 sensitivity was successfully developed for all cell lines. The sensitization assay was developed as following: cells were reversely transfected with individual siRNA for 24hr followed by the treatment of various concentrations of GSK295 for 72hr when cell viability was measured. Among 3 optimized cell lines, the A427 cell line, which appeared to be relatively more resistant to GSK295, was selected for a primary RNAi screen against 14,000 siRNA sequences covering 7,000 gene targets (Druggable Genome). Primary screen data was rigorously evaluated for multiple quality control metrics and found to exceed all expected performance parameters with &gt;98% global transfection efficiency, &lt;0.25 CV values, and minimal plate-to-plate and set-to-set variations observed. The top 10% drug sensitization hits were chosen, of which 240 of them were confirmed in subsequent analysis with the A427 cell line. To further validate these sensitizers to GSK295 and to eliminate the off-target effects, we compared the response of these sensitizers (4 unique sequences per gene target were selected) to GSK295 in two other NSCLC cell lines (A549 and NCI-H460) and selected the validated hits that have two or more unique siRNA sequences per gene target demonstrating sensitization to GSK295 response. Additionally, 23 chemical compounds targeting 16 of the top validated RNAi hits from the screen were tested for synergistic combination with GSK295. Notable synergism with GSK295 was observed with 10 inhibitors against 7 validated RNAi gene targets. In conclusion, the results yielded multiple sensitizing gene targets, with a high correlation between the targets that showed RNAi sensitization as well as synergy in combination with small molecules that inhibit the same targets. These new targets represent candidate GSK923295 sensitizing targets that warrant further investigation to support the development of rational GSK923295 combinations to maximize therapeutic efficacy in the clinic.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):PR-10.