bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract LB-252: Enzymology of the mechanism of action for MDX-1203 antibody drug conjugate
Authors: Derwin Daniel W. , Passmore David , Zhang Qian , Sufi Bilal , Pan Chin , Rao Chetana , Huber Mary , Gangwar Sanjeev , Cardarelli Pina , Deshpande Shrikant , Rangan Vangipuram 
Published: August 2012

Abstract
MDX-1203 is an antibody drug conjugate under clinical evaluation by Bristol-Myers Squibb. The antibody portion is MDX-1115, a fully human anti-CD70 IgG. The drug portion is MED-2460, a small molecule which itself is composed of the releasable prodrug MED-2284, a cleavable di-peptide linker, and a maleimide reactive group intended to facilitate protein attachment. The mechanism of action of MDX-1203 involves tumor specific delivery and cellular uptake of ADC, followed by the intervention of two different enzymatic pathways. Release of prodrug is accomplished through proteolysis of a citruline-valine di-peptide linker, presumably by Cathepsin B activity in the acidic environment of the lysosome. Activation of released prodrug, MED-2284, occurs in the endoplasmic reticulum via esterase cleavage in the of the piperazine protecting group by the enzyme human Carboxylesterase 2. Michaelis Menten methodologies are used to probe activity of each enzymatic pathway and their relative role in the activity of the drug. Proteolysis is investigated through the use of Human Liver Cathepsin B protease. A kinetic model is constructed for a cysteine modified analogue MED-2460, and then applied to the more complex system involving antibody conjugated drug. Enzymatic activation of released prodrug MED-2284 is investigated with recombinant Human Carboxylesterase 2. For each pathway, the kinetic parameters Km, kcat, and enzymatic efficiency are measured and reported. Parameters are compared in an effort to define the enzymatic rate limiting step in the activation MDX-1203, and define their respective roles in the overall activity of the drug.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-252. doi:1538-7445.AM2012-LB-252
Abstract LB-257: Ganitumab (AMG 479), an anti IGF-1R antibody, inhibits the proliferation of melanoma cells
Authors: Von Euw Erika M. , Konkankit Veerauo V. , Gong Ke-Wei , Calzone Frank , Finn Richard S. , Chmielowski Bartosz , Slamon Dennis J. 
Published: August 2012

Abstract
It has been shown that the Insulin-like growth factor receptor type I (IGF-1R) signaling pathway is highly active in metastatic melanoma. IGF-1 binding induces autophosphorylation of IGF-1R and initiation of MAPK and Akt pathways signaling which control cellular proliferation and survival. IGF-1 is a critical factor for growth of many types of cancer, including melanomas, and inhibition of its activity can trigger apoptosis by suppressing the PI3K-AKT and MAPK pathways. Our main objective in this study was to evaluate the therapeutic potential of a novel antibody to the IGF-1R (ganitumab) in a large panel of melanoma cancer cells. We have evaluated 41 human melanoma lines with well established genotypes. Among the 41 cell lines, 22 harbored the BRAF mutation, 10 were NRAS mutant and 9 were wild type for BRAF and NRAS mutations. Treatment with ganitumab (100µg/ml) resulted in inhibition of cell proliferation at 120 hrs in 20 out of 41 cell lines. We found that the response to ganitumab was independent of genotype. We chose 6 cell lines, 3 from the responder population and 3 non-responders (2 BRAF, 2 NRAS and 2 wild types) to further investigate the mechanism of action of ganitumab. Results from flow cytometry suggest that treatment of melanoma cells with 100 µg/ml ganitumab caused a 10% increase in apoptosis 72 hrs after treatment in sensitive cell lines compared with the resistant cell lines where we could not detect an increase in apoptotic cells. The effect of ganitumab was also investigated in a 3D colony soft agar formation assay. Melanoma cell lines sensitive to ganitumab showed a significant reduction in the ability to form colonies in soft agar compared with the cells that did not respond to the antibody. Ganitumab treatment led to a decrease in pAKT, pERK and pS6 in sensitive cell lines regardless of their driver oncogenic mutations when compared with non responder cell lines that showed no inhibition of these markers. In conclusion, inhibition of oncogenic MAPK and PI3K signaling by ganitumab resulted in activity in vitro against a large subset of melanoma cell lines. Our findings provide the rationale for further preclinical evaluation of ganitumab as a melanoma therapeutic.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-257. doi:1538-7445.AM2012-LB-257
Abstract LB-258: Developing therapeutic siRNA against HER2 in breast cancer cells
Authors: Hu Zhi , Gu Shenda , Rantala Juha , Ngamcherdtrakul Worapol , Yantasee Wassana , Gray Joe W. 
Published: August 2012

Abstract
Over-expression of oncogene HER2 was found in 20-30% primary breast cancers which involved in tumor initiation and progression. Breast cancer patients with high levels of HER2 (HER2 positive) showed poor clinical outcome. Increasing evidence indicated that the majority of patients with HER2 positive did not respond well to anti-HER2 drugs Trastuzumab (Herceptin) and Lapatinib. Even those who showed initial response ultimately became resistant to the treatment. The molecular mechanism of resistance includes the mutation of HER2 gene and the blocking of antigen of HER2 protein. The discovery of small interfering RNA (siRNA) raises the possibility of exploring new approach for cancer treatment. The siRNA against HER2 (siHER2) can reduce HER2 protein level by degrading mRNA expression. In our study, seventy-six siRNA sequences targeting the coding region of human HER2 gene were designed and synthesized. We quantified the RNA levels of HER2 and cell viability after HER2+ breast cancer cells (BT474, SkBr3 HCC1954) were transfected with siHER2 and scramble control siRNAs. Ten siRNA sequences were selected with greater than 50% knockdown efficiency and 40% inhibition of cell viability. We also measured the dose of 50% inhibition of cell growth (GI50) of top 5 siHER2 sequences in 20 HER2+ cell lines. The GI50 data showed that most of cell lines which were resistant to Trastuzumab were still sensitive to siHER2 treatment. Therefore, our data indicated that the siRNA against HER2 can potentially be used to overcome resistance of HER2 drugs, making it an alternative cancer therapeutic for HER2 positive patients. Currently, in vivo delivery of optimized siHER2 using nanoparticle is under evaluation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-258. doi:1538-7445.AM2012-LB-258
Abstract LB-259: Knockdown of slingshot2 serine phosphatase induces caspase3 activation in human carcinoma cell lines with the loss of the Birt-Hogg-Dubé tumor suppressor gene
Authors: Lu Xiaohong , Boora Uncaar , Fenton Janine , Reiman Anne , Seebra Laurence , Maher Eamonn R. 
Published: August 2012

Abstract
Birt-Hogg-Dubé (BHD) Syndrome, is a dominantly familial cancer syndrome associated with susceptibility to renal cancer carcinoma (RCC) caused by inactivating mutations in the folliculin (FLCN) gene. The precise functions of the FLCN gene product are still under investigation but RCC from BHD patients show loss of the wild type allele consistent with a tumour suppressor gene function. In search for potential synthetic-lethal targets for FLCN using a phosphatase siRNA library screen approach, we found that knockdown of SSH2 serine phosphatase (one of the three members of Slingshot family and actively involved in Actin reorganization) specifically induced caspase 3/7 activity in a dose-dependent manner (up to 6 fold increase, 10nM, 72hrs) in two human cell lines (BHD-origin renal cell carcinoma UOK-257 and thyroid carcinoma FTC-133) with loss of FLCN expression, but not in their folliculin expressing isogenic cell lines. SSH2 siRNA-induced knockdown was verified by real-time PCR (up to 60% reduction in SSH2 transcripts, 10nM siRNA, 48hrs), but SSH1 and SSH3 transcripts were increased up to 3 fold (suggesting a compensatory regulatory mechanism among members of SSH family). Further investigation of the underlining mechanism of caspase induction by SSH2 knockdown in FLCN-null cells exhibited that there was a dose-dependent increase in G1 cell population (up to 20% increase, 20nM SSH2 siRNA, 72hrs). Combination treatment of SSH2 + SSH1 siRNAs, but not SSH2 + SSH3 siRNAs potentiated induction of caspase 3 activity and G1 cell cycle arrest. These data indicate that apoptotic cell death in FLCN-null cells can be triggered by SSH2 knockdown through G1 arrest and provide a tool to develop potential therapeutic agents for BHD patients.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-259. doi:1538-7445.AM2012-LB-259
Abstract LB-260: Identification of DTYMK and CHEK1 as therapeutic targets in LKB1 mutant non-small cell lung cancer
Authors: Liu Yan , Cowley Glenn S. , Cohoon Travis J. , Root David E. , Kwok-kin Wong 
Published: August 2012

Abstract
The LKB1 tumor suppressor encodes a key metabolic sensor that integrates cell growth and metabolism. LKB1 is mutationally inactivated in multiple adult malignancies, including &gt;20% of lung cancers, often simultaneously with activating KRAS mutations. LKB1 mutations are an important predictor of poor outcome and resistance to current therapeutic approaches. We employed an integrative approach to define novel therapeutic targets in Lkb1 mutant lung cancers. Matched cell lines from genetically engineered mouse models of cancer driven by activated Kras alone or in combination with Lkb1 deletion, were employed in high-throughput RNAi, kinase inhibitor, and metabolite screens. These screens identified knockdown of either Dtymk (deoxythymidylate kinase) or Chek1 (checkpoint kinase 1) as synthetically lethal with Lkb1 deficiency in both mouse and human lung cancer cell lines, and revealed that Lkb1 inactivation conferred marked sensitivity to treatment with CHEK1 inhibitors. Lkb1 deficient cells had a distinct metabolic profile, characterized by striking decreases in multiple nucleotide metabolites. Knockdown of DTYMK inhibited dTTP biosynthesis and, consequently, DNA synthesis, and knockdown of CHEK1 caused accumulation of DNA damage. We hypothesize that Lkb1 loss enhances dependence on these enzymes due to broad defects in nucleotide metabolism. Our studies support the development of therapies target DTYMK and CHEK1 in LKB1 mutant non-small cell lung cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-260. doi:1538-7445.AM2012-LB-260
Abstract LB-262: Targeting T-type calcium channels induces the extrinsic apoptotic pathway and sensitizes glioblastoma cancer cells to radio- and chemotherapy
Authors: Dziegielewski Jaroslaw , Valerie Nicholas C. K. , Dziegielewska Barbara , Hosing Amol S. , Gray Lloyd S. , Larner James M. 
Published: August 2012

Abstract
The purpose of this study is to develop a novel and effective mechanistic target for sensitizing glioblastoma tumors to anti-cancer therapy. Glioblastoma multiforme (GBM) are primary brain tumors with an exceptional resistance to radio- and chemotherapy and, therefore, have extremely poor prognosis. Conventional treatment consists of aggressive surgery, chemotherapy and/or radiotherapy; however in spite of these treatments, the median survival of GBM patients is only 9 to 12 months. T-type channels are a type of voltage-gated calcium channel important for normal cell proliferation and differentiation, but they could be also over-expressed or aberrantly activated in several human cancers, including GBM. In this study we investigate the effects of T-type channel inactivation, either by selective antagonists (mibefradil and TTL1177) or by siRNA-directed knock-down, on GBM cells survival and resistance to therapy in vitro. Our results show that blocking T-type channels not only reversibly arrests cells in G1/G0 phase of the cell cycle but also induces irreversible loss of clonogenic potential and cell death. The execution of cell death is preceded (or coincides) by induction of autophagy, as characterized by LC-3 cleavage and punctuate staining. Furthermore, we also establish that inactivation of T-type channels stimulates the extrinsic pathway of programmed cell death, as evidenced by caspase 8 activation and Bid protein cleavage. Finally, we demonstrate that inactivation of T-type calcium channels sensitizes GBM cells to radio- and chemotherapy. Taken together with the promising outcomes of the in vivo mibefradil plus temozolomide trials, our studies suggest that targeting T-type calcium channels could be a novel and very efficient therapy for glioblastoma brain tumors, either as a single modality or in combination with already established modalities. (This work was financed in part by the University of Virginia Cancer Center Pilot Grant, the Department of Radiation Oncology Pilot Grant and the Department of Chemistry Research Fund)
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-262. doi:1538-7445.AM2012-LB-262
Abstract LB-263: Synthetic lethal targeting of PTEN-associated homologous recombination (HR) deficient melanoma cells by human apurinic/apyrimidinic endonuclease (APE1) inhibitors
Authors: Abbotts Rachel M. , Sultana Rebeka , Seedhouse Claire , Patel Poulam M. , Wilson David M. , Madhusudan Srinivasan 
Published: August 2012

Abstract
Background Mutation of the tumour suppressor PTEN is well-characterised in many advanced malignancies, including 30-50% of metastatic melanomas. Emerging evidence suggests a new role for PTEN in DNA repair, through transcriptional downregulation of the critical HR protein RAD51. Tumour cells deficient in HR (such as BRCA-deficient breast and ovarian cancers) have been therapeutically targeted in a synthetic lethality (SL) strategy using PARP inhibitors that block single strand break repair (SSBR), a pathway related to base excision repair (BER). We have previously identified novel inhibitors of the critical BER enzyme APE1, and demonstrated these can induce SL in BRCA-deficient cell lines. In the current study, we have evaluated SL relationships in PTEN-proficient and -deficient melanoma systems for a potential novel treatment strategy. Method We screened a panel of melanoma cell lines (MeWo, MM418, SkMel28, SkMel30, HT144, UACC62) for PTEN, APE1 and RAD51 protein expression. We tested for SL using clonogenic survival assays in PTEN- and RAD51-deficient cell lines using our recently developed APE1 DNA repair domain inhibitors, methoxyamine (indirect APE1 inhibitor) and NU1025 (PARP inhibitor), either alone or in combination. Aldehyde reactive probe assay, neutral comet assay, γH2AX immunofluorescence and FACS analyses were performed to confirm biological activity in cells. Results Of the screened cell lines, SkMel28, HT144 and UACC62 were deficient in PTEN and RAD51 protein expression. APE1 inhibitors were more toxic to PTEN-deficient cells compared to PTEN-proficient cells (p&lt;0.01). Significant sensitivity was also seen in PTEN-deficient cells treated with methoxyamine (p&lt;0.05) and PARP inhibitors (p&lt;0.001), confirming that BER modulation results in SL in PTEN deficiency. This increased cytotoxicity in PTEN deficiency is associated with accumulation of DNA double strand breaks (DSB), as assessed by comet assay (p&lt;0.001) and γH2AX accumulation (p&lt;0.05). DSB accumulation leads to G2/M arrest and apoptosis, as demonstrated by FACS analysis. Conclusion Our data provides the first pre-clinical evidence that targeting APE1 in PTEN-RAD51 deficient melanoma cells is a promising new SL strategy. We are complementing the current small molecule studies by developing PTEN knockout systems using shRNA technology.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-263. doi:1538-7445.AM2012-LB-263
Abstract LB-267: A role for the Sin3 histone deacetylase complex in cell migration
Authors: Smith Karen T. , Martin-Brown Skylar A. , Seidel Chris , Mushegian Arcady , Egidy Rhonda , Florens Laurence , Washburn Michael P. , Workman Jerry L. 
Published: August 2012

Abstract
Histone deacetylases (HDACs) remove acetyl groups from histones and other proteins, leading to alterations in protein activity and gene expression. Drugs that target these enzymes (HDAC inhibitors or HDACis) are currently approved for the treatment of specific cancers and are under study in numerous additional clinical trials. These drugs work by causing cell cycle arrest, differentiation or apoptosis. However, less is known about their potential effects on cancer cell migration and invasion, processes implicated in metastasis. There are eleven human zinc dependent histone deacetylases and many HDACis target several of these structurally related proteins in cells. Our studies are focused on HDACs1 and 2 which reside in large protein complexes, one of which is the Sin3 complex. This complex is important for promoter-mediated histone deacetylation, transcriptional repression and cell cycle control. We previously found that specific HDACis disrupt the function of the Sin3 complex in distinct ways. Here we describe the function of a novel subunit of the Sin3 complex, a previously uncharacterized protein, named “Family with sequence similarity 60, member A” (FAM60A). We find that FAM60A represses expression of genes linked to cancer cell migration and invasion. Moreover, we show that loss of FAM60A, or a core subunit of the Sin3 complex can increase the migration of lung cancer cells. This suggests that not all HDAC-related functions are cancer promoting, and adds to data suggesting that some HDAC-related functions may act in steps in metastasis suppression pathways. This suggests that some HDACis could increase the potential for metastasis. Current studies are focused on delineating the cancer-promoting functions of the complex from those that are tumor or metastasis suppressive and testing the effects of specific HDACis on cancer cell migration and invasion.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-267. doi:1538-7445.AM2012-LB-267
Abstract LB-269: A new role for the gain-of-function activity of p53 in breast cancer
Authors: St-Pierre Yves 
Published: August 2012

Abstract
Using tissue microarrays constructed from samples obtained from normal breast tissues and breast carcinomas, we previously found that galectin-7 is specifically expressed in myoepithelial cells but not luminal cells. We also found that abnormally high levels of galectin-7 were restricted to basal-like breast cancers, a heterogeneous group of cancers with a poor prognosis. These results were consistent with the genomic profiling data previously reported by the group of Charles Perou who recently provided a molecular portrait of human breast tumors. Their data revealed that while galectin-7 transcripts were expressed at low levels in normal breast tissues and mammary epithelial cell lines, they were highly expressed in estrogen receptor (ER)-negative breast cancer. Our data were also consistent with microarray studies by Jones and colleagues who identified galectin-7 as a myoepithelial-specific genes. In fact, galectin-7 ranked first on a list of 42 most predictive genes that distinguish luminal and myoepithelial cells. This expression of galectin-7 is not only important to study in terms of biomarkers of aggressive forms of breast cancer, but also because increased galectin-7 in breast cancer cells is known to increase their metastatic behavior. However, the expression of galectin-7 in aggressive forms of breast cancer is somewhat paradoxical if not surprising because galectin-7 has been considered an apoptosis regulator under the control of p53. In a previous report, Galectin-7 (also called p53-induced gene 1) was found to be one of the 14 transcripts that were induced by wild-type p53 in colon cancer cells. Here, we have examined this apparent contradiction by investigating the molecular mechanisms controlling galectin-7 expression in human breast cancer cells. We found that galectin-7 expression in human breast cancer cells is dictated by a gain-of-function activity of mutant p53. This conclusion is based on the following: 1) expression of galectin-7 in cancer cell lines correlated with constitutively high levels of NF-κB activity; 2) transfection of NF-κB subunits or treatment of cells with TNFα, a well-known inducer of NF-κB, increased endogenous level of galectin-7; 3) inhibitors of NF-κB reduced constitutive galectin-7 expression; 4) transfection of a transcriptionally inactive form of p53 (R175H) into a p53-null human breast cancer cell line induced galectin-7 via increased NF-kB activity. These findings identify galectin-7 as a novel player through which mutp53 exerts its gain-of-function activity in breast cancer cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-269. doi:1538-7445.AM2012-LB-269