bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4539: Vascular endothelial growth factor gene polymorphisms and clinical outcome in advanced gastric cancer treated with FOLFOX
Authors: Kwon Hyuk-Chan , Kim Sung-Hyun , Oh Sung Yong , Lee Suee , Lee Ji Hyun , Graves Christian A. , Hwang Jung-Ah , Hong Seung Hyun , Kim Hyo-Jin , Camphausen Kevin , Lee Yeon-Su
Published: August 2012

Background: Single-nucleotide polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) gene may have an impact on tumor progression, and response to chemotherapy. The aim of this study is to evaluate the associations between VEGF SNPs and clinical outcome in advanced gastric cancer patients treated with oxaliplatin, 5-fluorouracil, and leucovorin (FOLFOX). Methods: One hundred ninety recurrent or metastatic gastric cancer patients were enrolled in this study and treated with FOLFOX regimen. Genomic DNA was isolated from whole blood, and six VEGF (-2578C/A, –2489C/T, –1498T/C, –634G/C, 936C/T, and 1612G/A) gene polymorphisms were analyzed by PCR. Results: Patients genotyped G/G for –634G/C gene polymorphism had lower response rate (22.2%) than those G/C or C/C (32.3%, 51.1%; p = 0.034). The median serum levels of VEGF was higher in G/G genotypes than G/C + C/C (724.1 pg/ml vs. 462.4 pg/ml, p = 0.041). Patients with the VEGF –634CG/C polymorphism G/C + C/C genotype had a longer time to progression (TTP) of 4.9 months, compared with the TTP of 3.5 months for those with the G/G (p = 0.012, log-rank test). By multivariate analysis, this G/G genotype of –634G/C polymorphism was identified as an independent prognostic factor (Hazard ratio 1.497, p = 0.017). No significant influence on overall survival (OS) was observed by the –634 G/C. However, other SNPs were not related to response rate, TTP, or OS. Conclusion: Our data suggest that G/G genotype of –634G/C polymorphism is related to the higher serum levels of VEGF, and poor clinical outcome in advanced gastric cancer patients. It may help to identify patients who are more sensitive to FOLFOX regimen.

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 4539. doi:1538-7445.AM2012-4539
Abstract 4543: Uptake of 18F-FDOPA analogue 3H-L-DOPA is mediated by large neutral amino acid transporter LAT1 in human glioblastoma
Authors: Youland Ryan S. , Kitange Gaspar J. , Pokorny Jenny L. , Sarkaria Jann N.
Published: August 2012

INTRODUCTION: The L-Type amino acid transporter 1 (LAT1) transports large neutral amino acids across the plasma membrane in a variety of cells. Positron emission tomography (PET) imaging with the amino acid tracer 6-18F-fluoro-L-dopa (18F-FDOPA) provides useful histological information in human gliomas in addition to providing better localizing information then CT or MRI alone. This study is the first to correlate LAT1 expression with uptake of the 18F-FDOPA analog, 3H-L-DOPA in human glioblastomas. METHODS: Endogenous expression of LAT1 was evaluated in two established glioblastoma multiforme (GBM) cell lines and three primary GBM xenografts using Western blotting and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Uptake of FDOPA was assessed in vitro using 3H-L-DOPA as an analog to 18F-FDOPA. Knockdown of LAT1 expression was achieved by lentiviral expression of anti-LAT1 shRNA in GBM lines with high LAT1 expression. The effect of LAT1 knockdown on 3H-L-DOPA uptake was then quantified. RESULTS: Results from Western blotting and qRT-PCR demonstrate that LAT1 is variably expressed in GBM. Levels of 3H-L-DOPA uptake were directly related to LAT1 expression (p<0.001) across the 5 lines. Knockdown of LAT1 was achieved in T98 cells (knockdown efficiency = 82.8%) and xenograft GBM 28 (knockdown efficiency = 73.7%) as confirmed by qRT-PCR and Western blotting. Knockdown of LAT1 reduced 3H-L-DOPA uptake by 57.2% (p<0.0001) in T98 and 52.1% in GBM 28 (p<0.001). CONCLUSIONS: This is the first report of 3H-L-DOPA uptake being driven by LAT1 in human GBM. Our findings suggest LAT1 as a transporter of 18F-FDOPA in GBM. Additional studies are underway to correlate LAT1 expression with PET 18F-FDOPA uptake in patients with GBM.

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 4543. doi:1538-7445.AM2012-4543
Abstract 4547: Clinical relevance of circulating tumor cells in esophageal cancer
Authors: Effenberger Katharina E. , Reeh Matthias , Riethdorf Sabine , Eichstaedt Dominique , Izbicki Jakob R. , Bockhorn Maximilian , Pantel Klaus
Published: August 2012

Background: Current modalities to predict tumor recurrence and survival in esophageal cancer are insufficient. Locoregional and distant relapse is even common in lymph node-negative patients and more precise staging methods are therefore needed. Little is known about the utility of circulating tumor cells (CTC) as staging tool in esophageal cancer. Methods: In a prospective study we identified CTC in peripheral blood of esophageal cancer patients by two separate methods. We enrolled 85 consecutive esophageal cancer patients (03/2010-10/2011) who were surgically resected (R0) and patients received neither neoadjuvant nor adjuvant therapy. Peripheral blood was taken at the time of primary surgery and CTC were detected by either manual MACS enrichment (anti-cytokeratin plus anti-EpCam) with subsequent anti-cytokeratin staining or the automated CellSearch system (cleared by the FDA for CTC detection in metastatic breast, colon and prostate cancer) in parallel. CTC detection rates and correlation with clinicopathologic parameters were evaluated. The median clinical follow-up time is 11 months ranging from 1 to 19 months. Results: So far, 67 patients have been analysed of which 21 (31.3%) had CTCs using MACS, and 10 (14.9%) using CellSearch. CTCs detected with MACS significantly correlated with tumor size (p=0.040) and aggressive tumor biology as indicated by presence of regional lymph node (p=0.040) and distant metastases (p=0.019). CTCs detected with CellSearch correlated significantly with lymph node (p=0.044) and distant metastases (p=0.045), while no correlation was observed for tumor size or grading. CTC-positive patients had a worse overall survival than CTC-negative patients when tested with the CellSearch system (p=0.009). Conclusion: The presence of CTCs in patients with resectable esophageal cancer correlates with clinicopathologic risk factors.and predicts an unfavorable prognosis. Thus, our pilot study suggests that CTC detection may contribute to an improved staging in esophageal 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 4547. doi:1538-7445.AM2012-4547
Abstract 4554: QPCR and sequence analysis of DNA template from a microfluidic CTC isolation platform
Authors: Strauss William , Parker Alex , Juhn Frank , Cronin Maureen , White Emily , Vahidi Behrad , Fang Cong , Klem Erich , Vasko Robert , Romero Juan , Tabchy Adel , Dempsey Paul
Published: August 2012

Sequence analysis and quantitative allele specific PCR (QPCR) methods permit genetic profiling of cancer for targeted therapeutic selection; such personalized treatments have been associated with improved outcomes in cancer. Circulating tumor cells (CTC) offer a minimally-invasive opportunity for serial patient sampling, and potentially a means of tracking the molecular evolution that underlies the behavior and response phenotype of the disease including potential therapeutic response markers. Acquiring these types of patient profiles requires a platform and workflow providing reliable detection and recovery of small numbers of mutation-bearing CTC from a blood sample. Availability of such an enabling platform is a necessary prerequisite to the clinical correlation studies needed to demonstrate the utility of mutation-bearing CTC to patient care. We have successfully purified CTCs and converted them into DNA template of sufficient purity and quality to support multiple non-overlapping advanced molecular characterizations. Beginning with whole human blood spiked with defined numbers of cultured cancer cells as surrogates for CTCs, cells were successfully fluid-phase labeled using an anti-EpCAM antibody ferrofluid. Using a proprietary microfluidic sheath flow technology, EpCAM positive, cytokeratin staining cells were selected from 2 to 4 ml of labeled blood. This method produced sufficient DNA template for multiple analyses per patient sample. QPCR analysis of these templates demonstrated reproducible detection of fewer than 1% target cells in a background of non-target cells, allowing detection of the KRAS G12S mutation from as few as 5 recaptured cancer cells. The same DNA templates were then used for hybrid capture and next-generation sequencing of a panel of more than 200 cancer-related genes. This sequencing platform was able to detect multiple somatic mutations in genomic DNA templates produced from samples containing as few as 10 cancer cells per milliliter of blood. Together these data provide initial proof-of-concept for a system capable of detecting and characterizing mutations across any specified set of genes within purified CTC populations.

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 4554. doi:1538-7445.AM2012-4554
Abstract 4555: Protein and glycan biomarkers of malignant potential in pancreatic cyst fluid
Authors: Maupin Kevin , Curnutte Bryan , Cao Zheng , Partyka Katie , McDonald Mitch , Kwon Richard , Allen Peter , Brand Randall , Simeone Diane , Haab Brian B.
Published: August 2012

The early detection of a portion of pancreatic cancer precursors_cystic neoplasms of the pancreas_is possible through high-resolution abdominal imaging, providing an opportunity to successfully treat these lesions before they become invasive. The increased use of abdominal imaging has led to a higher rate of identifying pancreatic cysts, but currently it is not possible to accurately determine which cysts have high malignant potential and should be removed. Our previous work showed that the glycosylation and abundance of specific proteins in the cyst fluid was significantly different between potentially malignant cysts and benign cysts, providing leads for biomarkers to guide patient management. In this work we tested the hypothesis that a panel of specific protein glycoforms forms an accurate biomarker for pancreatic cysts with high malignant potential. Using antibody-lectin sandwich arrays, screens of nearly 100 different candidate markers and multiple glycoforms of each marker confirmed previous results and also showed that two distinct glycan structures are present on several proteins at high levels in the cyst fluid of cancer precursors (intraductal pancreatic mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN)) but not in benign cysts (serous cystadenomas (SC) and pseudocysts (PC)). The glycans, N-acetyl glucosamine and the blood group H structure, previously have not been recognized as cancer biomarkers. A six-marker panel comprising the measurement of one of these glycans on MUC5AC, MUC16, endorepellin, and fibronectin correctly detected 37 of 39 (95%) potential cancer precursors and 16 of 18 (89%) of the benign cysts. This performance significantly surpasses current diagnostic accuracy. The validation of this biomarker panel could lead to more accurate treatment decisions for patients with potentially malignant cysts while sparing patients with benign cysts from unnecessary procedures.

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 4555. doi:1538-7445.AM2012-4555
Abstract 456: The Alpha9 nicotinic acetylcholine receptor is the key mediator In nicotine-enhanced cancer metastasis in breast cancer cells
Authors: Wei Po-Li , Hung Chin-Sheng , Chang Yu-Jia
Published: August 2012

Background/purpose: The tobacco-specific mitogen nicotine was reported to correlate with cancer progression and tumorigenesis in breast cancer. Metastasis is a major cause of cancer death, so the influence of nicotine on breast cancer cell migration is also of interest. Our aim is to elucidate the mechanisms of nicotine-enhanced migration of breast cancer cells and thereby achieve better control of metastasis. Methods: The influence of nicotine on breast cancer cell migration was evaluated by trans-well and wound-healing migration assays. Receptor-mediated migration was studied with both a small molecule. inhibitor and small interfering RNA (siRNA). Results: The alpha9 nicotinic acetylcholine receptor, a9nAChR, was identified in breast cancer cell lines MCF-7 and MDA-MB-231. Nicotine enhanced cell migration in both trans-well and wound-healing migration assays. We used a specific inhibitor and siRNA to demonstrate that a9nAChR is the key modulator in mediating nicotine-enhanced breast cancer cell migration through up-regulation of fibronectin and vimentin. Conclusion: Nicotine treatment enhanced breast cancer metastasis through a9nAChR signaling via enhanced fibronectin and vimentin expression.

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 456. doi:1538-7445.AM2012-456
Abstract 4560: A new IGF-1-integrated Child-Pugh score to risk-stratify patients with hepatocellular carcinoma
Authors: Kaseb Ahmed O. , Xiao Lianchun , Hassan Manal M. , Shah Neeraj , Rashid Asif , Abbruzzese James L. , Morris Jeffrey
Published: August 2012

Purpose The Child-Pugh (CP) system is the major tool for assessing the underlying liver condition and guiding therapy decisions in hepatocellular carcinoma (HCC) patients. It is itself relatively quantitative and uses five empirically selected variables, including hepatic encephalopathy and ascites, which are clinically difficult to grade and may vary in severity according to medical management of patients. Insulin-like growth factor-1 (IGF-1) is produced predominantly in the liver, and hence reflects its synthetic function. Our study objective was to build a new CP score by integrating plasma IGF-1 level into the CP parameters to refine its prognostic stratification ability. Patients and Methods We prospectively collected plasma samples and clinical data from 310 individuals with HCC. IGF-1 levels were measured by ELISA and recursive partitioning was used to identify optimal cut points and IGF-1 ranges, using training and validation sets, and established the cut-off values of IGF-1 arranged so as to define the three distinct groups of IGF-1 with increasing liver function severity; A=1, B=2, and C=3. We then constructed the new score by replacing points from ascites and encephalopathy with plasma IGF-1 points; the new score points = 4-11. Finally, we performed log rank test for both systems, and also compared their prognostic abilities using concordance index (c-index). Results Compared with CP system, the new system (c -index = 0.608) improves the capacity in predicting OS and refined the stratification of all classes of the original CP (c-index = 0.573), (p value = 0.0029). Conclusion Replacing ascites and encephalopathy by plasma IGF-1 significantly improved prediction of OS and prognostic stratification of the conventional CP system. After external validation, the new scoring system may become the standard of care in guiding therapy decisions and stratifying HCC patients in clinical trials.

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 4560. doi:1538-7445.AM2012-4560
Abstract 4563: Monotherapy with a tumor-targeting mutant of Salmonella typhimurium inhibits human glioma in an orthotopic model in nude mice
Authors: Momiyama Masashi , Zhao Ming , Hiroshima Yukihiko , Suetsugu Atsushi , Tome Yasunori , Mii Sumiyuki , Yano Shuya , Bouvet Michael , Chishima Takashi , Endo Itaru , Hoffman Robert M.
Published: August 2012

Malignant glioma tumors are the most common primary central nervous system tumors. Despite the multidisciplinary approach to treatment, prognosis remains poor. In this study, we demonstrated that the Salmonella typhimurium A1-R tumor-targeting strain can inhibit and eradicate human glioma in an orthotopic nude mouse model. S. typhimuirum A1-R was administered by injection through a craniotomy open-window or intravenously in nude mice. To establish the model, 2×105 U87-RFP human glioma cells were injected stereotactically into the mouse brain through the craniotomy open window. Two weeks after glioma-cell implantation, mice were treated with S. typhimurium A1-R (2×107 CFU / 200 αl intravenous injection [i.v.] or 1×106 CFU / 1 αl intracranial injection [i.c.]) once a week for 3 weeks. Brain tumors were observed by fluorescence imaging through the craniotomy open window over time. S. typhimurium A1-R, administered i.c., inhibited brain tumor growth 7.6-fold compared with untreated mice (p = 0.009) and improved survival 73% (p = 0.001). Two of ten mice appeared to have their tumors eradicated. In contrast, intravenous administration of S. typhimurium A1-R was not effective. The craniotomy open window enabled observation of tumor growth in the brain in real time in both treated and untreated mice. The results of the present study demonstrate that bacterial therapy of brain cancer is a novel, effective and safe treatment strategy in a highly treatment-resistance 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 4563. doi:1538-7445.AM2012-4563
Abstract 4564: Dysregulated p15 in urothelial carcinoma of the upper urinary tract
Authors: Ho Pei-Yin , Tsai Yu-Chieh , Huang Chao-Yuan , Chung Shiu-Dong , Yang Hsin-Yi , Peng Hsiang-Chi , Lin Ching-Hung , Lai Ming-Kuen
Published: August 2012

OBJECTIVE: To investigate tumorigenic characteristics of upper urinary tract urothelial carcinoma (UTUC) by evaluating genomic alterations and protein expression of p15, located in 9p21, in primary tumors and in the morphologically normal pelvis of UTUC patients. METHODS: 10 pairs of tumor and pelvis tissues were submitted for comparative genomic hybridization (CGH) to examine chromosome abberations. Western blotting assays were performed to compare the fold change of p15 expression between another 16 pairs of tumor and normal tissues. Immunohistochemistry was conducted to determine the presence of p15-positive tumor cells and staining intensity in 53 tumor tissues, including 26 superficial and 27 invasive tumors. The Student's t-test and Chi-square test were applied to explore the correlation between the p15 expression and clinicopathologic parameters of UTUC patients. RESULTS AND CONCLUSIONS: CGH revealed incomplete 9p21 in 70% of UTUC tumors, including 3 low-grade and 7 high-grade cases. Results of Western blotting assays showed high frequencies (75%) of p15 downregulation (fold change > 1.5) in UTUC tissues compared to their normal pelvis control. Immunohistochemistry results indicated that superficial tumors had lower p15 expression than invasive tumors (p=0.002). In patients with tumor metastases, local recurrence or distal recurrence, the p15 expression level was significantly increased in UTUC tissues (p=0.038, 0.01 and 0.017, respectively). Taken together, our data suggest that the decreased expression of p15 may be an important step in early neoplastic transformation of the urothelium of upper urinary tract and, during tumor progression, p15 may be up-regulated by other molecules, such as SP-1.

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 4564. doi:1538-7445.AM2012-4564
Abstract 4565: Prediction of prognosis by the combination of mutation and methylation in colorectal cancer
Authors: Iida Satoru , Kato Shunsuke , Ishiguro Megumi , Ishikawa Toshiaki , Matsuyama Takatoshi , Kobayashi Hirotoshi , Higuchi Tetsuro , Uetake Hiroyuki , Sugihara Kenichi
Published: August 2012

Colorectal cancer (CRC) is among the most common types of cancer in both men and women and is associated with high mortality, particularly at advanced stages. Markers for defining individual risk signatures in CRC patients are of great clinical value, as they may allow for targeted therapies to improve outcomes in CRC patients. Epigenetic alteration such as promoter hypermethylation of gene, as well as genetic abnormality such as gene mutation, occurs frequently during the pathogenesis of human cancers. Recent studies exhibit the increasing observations that both epigenetic and genetic changes combine to determine the phenotype of cancer. Thus, in the present study, we examined KRAS and PIK3CA mutations and the methylation status of BNIP3, SFRP1, and Dkk1, and analyzed the correlation between these molecular alterations and the clinicopathological features of CRC. We aimed to clarify whether a combination of genetic and epigenetic alterations can be used to classify CRC patients in relation to their clinicopathological features and outcomes. Tissue samples from 122 CRC patients who underwent surgical resection were examined. The methylation status of SFRP1 and Dkk1 and the sequences of exon 1 of KRAS gene and exons 9 and 20 of the PIK3CA gene were determined by methylation specific PCR and direct sequencing, respectively, using genomic DNA extracted from paraffin-embedded blocks. Correlation between these factors and clinicopathologic findings/patients survival were examined. As a result, there was a significant correlation between KRAS mutation and BNIP3 (p=0.0004) or Dkk1 (p=0.0009) methylation but not SFRP1 (p=0.114). Although SFRP1 and Dkk1 methylation showed no associations with disease specific survival (DSS) and other clinicopathological findings in CRC patients, BNIP3 was associated with poor DSS (p=0.0149). In CRC without both KRAS and PIK3CA mutation, patients with two or three methylated genes had poorer overall survival compared to those with no or one methylated genes (p=0.0017). To contrary, in the cases of at least one or more mutations, patients with two or three methylated genes tended to have better survival than patients with no methylation. Classifying CRC based on BNIP3, SFRP1, and Dkk1 methylation status and KRAS and PIK3CA mutation may be a clinically powerful predictor of patient outcome.

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 4565. doi:1538-7445.AM2012-4565
Abstract 4682: Compensatory activation of alternative DNA repair pathways following exposure to the PARP Inhibitor ABT-888 in vitro and in patients with solid malignancies
Authors: Gao Li , Duan Wenrui , Wu Xin , Chen Alice , Otterson Gregory A. , Villalona Miguel A.
Published: August 2012

PARP inhibitors are being developed with the hope of inhibiting base excision repair in tumor cells following DNA insult. They do so by inhibiting poly ADP-ribose polymerase-1(PARP-1) which plays an important role in the repair of single-stranded DNA (ssDNA) breaks. Although some PARP inhibitors have been shown to suppress its target at safely achievable concentrations in humans, mono-therapy with these agents is generally not able to induce responses. The compensatory effect of alternative repair pathways, including., homologous recombination (HR) repair, nucleotide excision repair (NER), among others, could potentially be responsible for this lack of effect. Examples of HR repair proteins include those involved in the Fanconi Anemia/BRCA pathway and for NER, the ERCC proteins. We performed Western immunoblot analysis to evaluate the expression level of PAR, Fanconi Anemia D2, ERCC1 and beta-actin proteins in the human cancer cell lines H1299 (lung) and MDA-MB-231(breast) following exposure to the PARP inhibitor ABT-888 (veliparib). The expression level of these protein was also evaluated in human peripheral blood mononuclear cells (PBMCs) obtained from consenting patients with advanced solid malignancies participating in a dose escalation trial with ABT-888, as monotherapy or in combination with mitomycin C. PAR protein level was reduced at 6 hours post ABT-888 exposure (5μM) and maintained at low levels through 48 hours in the H1299 and MDA-MB-231cancer cells. However FANCD2 and ERCC1 protein expression was elevated simultaneously in these cancer cells post ABT-888. Similarly, FANCD2 and ERCC1 protein levels increased in the PBMCs of 22 patients analyzed following ABT-888 as a single agent (n=12) or in combination with mitomycin C (n=10). These results confirm that ABT888 can inhibit its target PAR expression both in cancer cells and patients’ PBMCs. However, our results also show that ABT-888 up-regulates homologous recombination (HR) and nucleotide excision repair (NER) pathways, which have the potential of resulting in not only resistance to the antitumor effect of ABT-888, but also in decreasing the effect of DNA targeting cytotoxic chemotherapy when combined with isolated PARP inhibition. It is plausible that cancers with defective FA or NER pathways, which are incapable of mounting a compensatory response, would represent a better target for ABT-888 alone or in combination with DNA targeted cytotoxic chemotherapy. Experiments aimed to evaluate this notion are underway. The potential role of other compensatory repair mechanisms also merit further investigation.

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 4682. doi:1538-7445.AM2012-4682
Abstract 4684: Synthetic lethal interaction between EGFR and PARP inhibition
Authors: Whitley Alexander , Nowsheen Somaira , Cooper Tiffiny , LoBuglio Albert , Bonner James , Yang Eddy S.
Published: August 2012

Purpose: Dysregulation of the epidermal growth factor receptor (EGFR) family is a hallmark of many cancers. Although targeting of EGFR family has improved outcomes, many patients ultimately fail this therapy. PARP inhibitors (PARPi) have gained recent attention due to their unique selectivity in killing homologous recombination (HR)-deficient tumors while maintaining minimal toxicity in normal tissues. We have previously shown that EGFR inhibition induces synthetic lethality with PARPi in head and neck squamous cell carcinomas (HNSCCs) in vitro by attenuating DNA repair pathways. In this study, we validated these observations in vivo in HNSCCs xenografts. Importantly, we also tested this strategy in other EGFR dysregulated cancers. Methods: Cervical, breast, and head and neck cancer cell lines were used in this study. DNA damage and repair were assessed by immunofluorescence staining of cells for γ-H2AX, Rad51, and DNA-Pk foci and/or chromosomally integrated HR and nonhomologous end-joining based GFP reporter assays. Cell viability was determined via colony formation and ATPlite assays. Tumor growth delay was assessed in mice bearing tumor xenografts. Results: Combined EGFR and PARP inhibition resulted in the greatest tumor growth delay versus either agent alone in mice bearing head and neck tumor xenografts (9 week tumor growth delay when compared to PARPi alone, 3 week tumor growth delay when compared to EGFR inhibitor alone). This correlated with persistent γ-H2AX foci indicative of unresolved DNA damage. Interestingly, this combination was also effective in other EGFR dysregulated tumors. Human cervical and breast cancer cells exhibited enhanced cytotoxicity with EGFR and PARP inhibition compared to either agent alone (80-99% cytotoxicity with combination vs 0-20% with either agent alone). Similar to head and neck cancer, susceptibility to PARPi induced by EGFR inhibition was associated with deficient NHEJ- and HR-mediated DNA repair and subsequent persistence of DNA damage. Conclusions: Thus, by generating a DNA repair deficit, EGFR inhibition can induce synthetic lethality with PARP inhibition. This can be an innovative treatment strategy for tumors with dysregulated EGFR signaling.

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 4684. doi:1538-7445.AM2012-4684
Abstract 4688: E7449: A novel PARP inhibitor enhances the efficacy of radiotherapy and chemotherapy and has potent single agent anticancer activity in BRCA-deficient tumors
Authors: McGonigle Sharon , Chen Zhihong , Wu Jiayi , Ackermann Karen , Tendyke Karen , Moniz George , Nomoto Kenichi
Published: August 2012

E7449 is an orally bioavailable, potent, small molecule inhibitor of Poly(ADP-ribose) Polymerase (PARP)1 and PARP2. PARP1 is a key molecule in sensing and repairing single strand DNA breaks via the base excision repair (BER) pathway and may also play a role in the repair of double strand DNA breaks. Both PARP1 and PARP2 are activated upon DNA damage with PARP1 activity accounting for the majority of the PARP response. Inhibition of PARP impairs DNA repair and potentiates the efficacy of DNA damaging chemotherapy and radiotherapy for cancer treatment. Additionally, PARP inhibition is effective as a single agent cancer therapy where there is an underlying defect in double strand DNA repair by homologous recombination (e.g., BRCA mutation). In this study we describe the development of the novel PARP inhibitor E7449. E7449 potently inhibits PARP1 and PARP2 in a cell-free assay and potentiates the cytotoxicity of both radiotherapy and chemotherapy. The cytotoxic effect of radiotherapy was enhanced by E7449 in clonogenic survival assays. The anti-tumor activity of the alkylating agent temozolomide was potentiated by E7449 in a dose responsive manner in vivo in the B16-F10 melanoma isograft mouse model. Daily dosing of E7449 as a single agent significantly inhibited tumor growth in a genetically engineered BRCA1 null mouse ovarian xenograft model. In the BRCA1 mutant human breast cancer cell line MDA-MB-436, E7449 significantly inhibited proliferation in a long term growth inhibition assay in vitro. Oral administration of E7449 once daily potently inhibited tumor growth in the MDA-MB-436 xenograft model with no toxicity observed. A dose responsive pharmacodynamic effect on PARP activity was demonstrated in MDA-MB-436 tumor tissue following administration of a single E7449 dose. The decrease in PARP activity was sustained over several hours. The ability of E7449 to inhibit PARP activity in tumor tissue was further investigated in the H460 xenograft model. Following single oral administration of various E7449 dosages, inhibition of PARP activity in tumor tissue was determined over time. Studies revealed that PARP is inhibited by E7449 in a time and dose dependent manner with lower doses resulting in transient inhibition and higher doses causing more complete and sustained PARP inhibition. Conclusion: E7449 is a potent and selective PARP1 and PARP2 inhibitor with potent anti-tumor activity in BRCA-deficient in vivo models. It also potentiates the activity of radiotherapy and chemotherapy pre-clinically. Evaluation of E7449 in a Phase 1 study will be initiated soon.

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 4688. doi:1538-7445.AM2012-4688
Abstract 4689: Stabilization of PARP-DNA complexes plays a critical role for the cytotoxic effects of the PARP inhibitors, veliparib and oliparib
Authors: Pommier Yves G. , Murai Junko , Takeda Shunichi
Published: August 2012

Poly(ADPribose) (PAR) polymerase (PARP) inhibitors are in clinical trials with alkylating agents such as temozolomide and topoisomerase I (Top1) inhibitors such as camptothecin derivatives (topotecan and irinotecan). To elucidate the mechanism of action of PARP inhibitors and how they synergize with alkylating agents and Top1 inhibitors, we compared genetic PARP knockout versus chemical inhibition with the PARP inhibitor. DNA alkylation damage was assayed by treating wild type (WT) and PARP knockout chicken DT40 cells with methyl methane sulfonate (MMS) in the presence of oliparib or veliparib. Notably, PARP inhibitors produced a much greater cytotoxicity than knocking out the PARP gene in cells treated with low MMS concentrations that are not cytotoxic in WT cells. Moreover, knocking out PARP eliminated the cytotoxicity of the PARP inhibitors even in the absence of MMS treatment. These results suggested that PARP inhibitors not only act by abrogating the catalytic activity of PARP and blocking PAR polymer formation but also by poisoning PARP. To further investigate this possibility, we measured PARP binding to DNA. Accordingly, we found that both oliparib and veliparib trap PARP on cellular DNA. By contrast, in the case of Top1 inhibitors, the potentiation by PARP inhibitors was no greater than knocking out PARP. Together, these results demonstrate that oliparib and veliparib act primarily as catalytic PARP inhibitors for Top1-linked DNA damage, whereas, in the case of base damage, oliparib and veliparib also act by preventing the removal of PARP complexes from DNA, probably as a result of defective PARP auto-PARylation, thereby converting base damage and DNA nicks into tight PARP-DNA complexes.

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 4689. doi:1538-7445.AM2012-4689
Abstract 4690: PARP inhibition increases sensitivity to cisplatin in ERCC1-low non-small cell lung cancers
Authors: Cheng Haiying , Zhang Zhenfeng , Borczuk Alain , Powell Charles A. , Halmos Balazs
Published: August 2012

Platinum compounds are the foundation of chemotherapy regimens for non-small cell lung cancer (NSCLC) but nevertheless response rates are disappointing and response duration is limited. Tumor expression of ERCC1, a key enzyme in nucleotide excision repair, may correlate with clinical response to platinum agents. Inhibition of poly(ADP-ribose) polymerases (PARPs), enzymes essential for base excision repair, enhances platinum sensitivity in BRCA-associated breast and ovarian cancers. We hypothesized that combining PARP inhibition with platinum compounds for tumors with low ERCC1 expression, may be an approach to optimize platinum-based therapy for NSCLC. In primary lung tumor specimens and NSCLC cell lines, PARP1 was found to be a mainly nuclear protein with higher expression in tumor cells as compared to normal counterparts. Drug combination experiments revealed that olaparib (PARP inhibitor) selectively synergized with cisplatin in ERCC1-low HCC827 and PC9 but not in ERCC1-high A549 and H157 lung cancer cells. Similar data were obtained with an alternative PARP inhibitor, veliparib (ABT-888). Moreover, siRNA-mediated knockdown of ERCC1 in ERCC1-high A549 and H157 cells increased sensitivities of both cisplatin and olaparib. Mechanistic studies further indicated that PARP inhibition alone or in combination with cisplatin led to cell cycle arrest in the G2/M phase, via activation of the DNA damage checkpoint pathways involving γH2AX, checkpoint kinase 1 and p53. These data suggest that there is a synthetically lethal relationship between PARP inhibition and ERCC1 loss in NSCLC that could be exploited for novel therapeutic approaches in lung cancer therapy based on tumor ERCC1 expression.

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 4690. doi:1538-7445.AM2012-4690
Abstract 4691: Rationale for combining PARP inhibitors with topotecan or irinotecan: taking advantage of the alternative DNA repair pathways involving XPF-ERCC1 and PARP-TDP1
Authors: Zhang Yongwei , Regairaz Marie , Seiler Jennifer , Agama Keli , Doroshow James , Pommier Yves
Published: August 2012

Poly(ADP-Ribose) (PAR) polymerase (PARP) inhibitors represent an important class of novel anticancer agents. The present study explores the molecular rationale for combining veliparib (ABT-888) with camptothecin (CPT) and its clinical derivatives, topotecan and irinotecan. ABT-888 inhibited PAR induction by CPT and increased CPT-induced cell killing and DNA damage measured by histone gamma-H2AX and comet assays. Notably, increased DNA breaks by ABT-888 was not associated with a corresponding increase of topoisomerase I cleavage complexes (Top1cc). Also, ABT-888 failed to further enhance the gamma-H2AX response in tyrosyl-DNA-phosphodiesterase (TDP1) knockout cells, which indicates that PARP inhibition no longer enhances Top1-induced DNA damage once TDP1 is inactivated. To explore alternative endonuclease pathway for the repair of Top1cc upon PARP inhibition, we tested the role of the 3′-flap endonuclease XPF-ERCC1. XPF-ERCC1 inactivation reduced the ABT-888-induced gamma-H2AX response both in non-replicating and replicating cells, and further enhanced the antiproliferative effect of ABT-888 in CPT-treated cells. Together, our findings demonstrate that XPF-ERCC1 acts as an alternative endonuclease pathway for the repair of Top1-induced DNA damage. Its function becomes critical when the PARP-TDP1 excision repair pathway is inactivated. Our study suggests the rationale for combining Top1 and PARP inhibitors in tumors with XPF-ERCC1 deficiency.

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 4691. doi:1538-7445.AM2012-4691
Abstract 4696: Expression of the DNA repair protein UNG predicts lung cancer sensitivity to pemetrexed
Authors: Weeks Lachelle D. , Gerson Stanton L. , Liu Lili
Published: August 2012

Uracil misincorporation is a direct consequence of TS inhibition by the multi-target antifolate, pemetrexed. The DNA base excision repair (BER) enzyme Uracil DNA glycosylase (UNG) is the major glycosylase responsible for the removal of misincorporated genomic uracil. We have previously illustrated that human colon cancer cells (DLD1) with engineered stable somatic knockout of UNG expression are hypersensitive to pemetrexed owing to the cytotoxicity of genomic uracil accumulation. Here, we examined the relationship between the expression of UNG and the pemetrexed sensitivity in a small panel of lung cancer cell lines (n∼10). The levels of UNG were measured by western blot (for protein) and RT-PCR (for mRNA). Results revealed that UNG mRNA expression is well correlated with protein expression in all cell lines. Moreover, there was a wide range of distribution of UNG levels in the lung cancer cell lines evaluated. UNG cutting assay and AP site measurements confirm that these differences in UNG expression result in varied potential for BER activation and subsequent AP site formation. To determine the role of this variation in UNG expression in pemetrexed cytotoxicity, colony survival studies were performed. In general, cell lines with higher UNG expression were more resistant to pemetrexed. H460 cells having 7-fold lower expression of UNG mRNA than H1975 cells are >5 fold more sensitive to pemetrexed than H1975 cells (H460 IC50 = 200nM; H1975 IC50 = >1000nM). Analysis of tissue microarray data in Oncomine confirms variations in UNG expression in primary human lung cancer samples. Moreover, small cell lung cancer and squamous cell lung cancer, both notoriously resistant to pemetrexed, have significantly increased median UNG expression compared to all other lung cancer subtypes (1.5-fold greater UNG expression p<0.005). These data motivate future evaluation of UNG as a clinical predictor of pemetrexed response using lung cancer biopsy specimens. Together, our results clearly indicate that the BER protein, UNG is differentially expressed in lung cancer cells. The inherent variation in UNG expression may have particular impact on our ability to predict the therapeutic efficacy of pemetrexed in 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 4696. doi:1538-7445.AM2012-4696
Abstract 4697: Identification, characterization and effects of inhibitors of the human Apurinic/Apyrimidinic Endonuclease 1 (APE1) protein
Authors: Srinivasan Ajay , Xie Xiang-Qun , Sobol Robert W. , Gold Barry
Published: August 2012

The human Apurinic/Apyrimidinic Endonuclease 1 (APE1) protein has distinct and possibly related functional roles in DNA damage repair and transcriptional regulation of gene expression. Due to its significant role in DNA repair, APE1 is a viable target for chemotherapeutic drugs; inhibition of DNA repair activity of APE1 potentates the cytotoxic effect of lesions caused by DNA-reactive drugs. Using a combination of in silico screening as well as in vitro enzyme-inhibition assays, we identified strong in vitro inhibitors (IC50 < 1 μM) of the APE1 protein. Using human glioblastoma (T98G) cells, it was demonstrated that these inhibitors potentiate the cytotoxicity of DNA damaging agents, especially alkylators, and that these compounds also cause increased accumulation of intracellular abasic sites. We investigated the association of the inhibitors with APE1 protein and DNA by means of CD, UV and fluorescence spectroscopies, and by a fluorescent intercalator/groove binder displacement assay.

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 4697. doi:1538-7445.AM2012-4697
Abstract 4699A: Hedgehog signaling (HH/Gli) transcriptionally regulates hTERT gene expression in human cancer cells
Authors: Mazumdar Tapati , DeVecchio Jennifer , Agyeman Akwasi , Shi Ting , Houghton Janet A.
Published: August 2012

Tightly coordinated Hedgehog (HH) signaling is critical during normal embryonic development. Aberrant HH signaling is involved in driving cell proliferation in multiple human cancers. Classical HH signaling involves the interaction of the soluble HH ligands with their receptor, Patched (Ptch), thereby releasing a transmembrane protein Smoothened (Smo) from Ptch-mediated inhibition. Smo then activates the Gli family of transcription factors that regulate HH target genes. We have previously reported that HH signaling provides essential survival support to human colon cancer cells and inhibition of this signal induces DNA damage and extensive cell death. However the downstream targets that govern the regulation of cell survival by HH/Gli in cancer cells are not completely defined. This study demonstrates that the Gli proteins transcriptionally regulate the expression of human telomerase reverse transcriptase (hTERT) gene in human cancer cells. hTERT is a known regulator of telomere homeostasis, which determines the replicative potential and hence the life span of cells. Suppression of both Gli1 and Gli2 functions by exogenous expression of a C-terminus truncated Gli3 repressor mutant (Gli3R), or by GANT61, a pharmacological inhibitor of Gli1 and Gli2 activity, reduced hTERT protein expression over a period of 72 hr in human colon, prostate and brain cancer cell lines. Further, exogenously expressed Gli2 significantly increased hTERT protein expression in human colon cancer cell lines. Exposure to GANT61 also inhibited hTERT mRNA expression within 24 hr in human colon cancer cell lines. Insilico analysis of the hTERT promoter revealed 7 putative Gli binding sites suggesting a transcriptional mode of regulation of hTERT expression by Gli2. Chromatin immunoprecipitation with Gli2 antibody precipitated fragments of the hTERT promoter in human colon cancer cell lines, indicating a direct interaction between Gli2 and the hTERT promoter. The binding between Gli2 and hTERT promoter was significantly reduced upon exposure to GANT61. Further, overexpression of the wild type hTERT cDNA in cancer cells prevented the cytotoxic effects of blocking the HH signaling pathway with GANT61. These findings demonstrate hTERT to be a direct transcriptional target and a critical mediator of the HH/Gli signaling pathway, and identify a previously unknown role of the HH/Gli axis in regulating the replication potential of cancer cells. These findings are of significance in understanding important regulatory mechanisms that determine the role of HH/Gli signaling in cancer cell survival.

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 4699A. doi:1538-7445.AM2012-4699A