bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 4603: TCF7L1 constrains Wnt/β-catenin signaling and tumor growth in pancreatic cancer
Authors: Kershaw Kathleen M. , Arensman Michael D. , Ho Bridgette , Lay Anna R. , Dawson Nicole A. , Dawson David W. 
Published: July 2016

Abstract
Wnt/β-catenin signaling plays important roles in pancreatic adenocarcinoma (PDA) tumor initiation and progression through its promotion of various pro-tumorigenic phenotypes. While RNF43 mutations increase Wnt signaling activity and confer Wnt growth-dependency in a subset of PDA, other key driver mutations in the Wnt pathway are only rarely encountered in PDA. To gain additional insights into alternative mechanisms contributing to increased Wnt pathway activity in PDA, we examined the expression and activity of LEF/TCF family members, the key transcriptional binding partners for β-catenin in canonical Wnt signaling. Luciferase-based β-catenin-activated reporter (BAR) assays demonstrated variable Wnt activity across a large panel of PDA cell lines, which was used to dichotomize cell lines into groups with high or lower β-catenin/TCF-dependent transcription. Supervised analysis of PDA cell line microarray data and parallel western blot analyses identified distinct patterns of TCF/LEF expression, including increased TCF7 and TCF7L2 (aka TCF4) expression in high BAR lines and increased TCF7L1 (aka TCF3) expression in low BAR lines. RNAi-mediated knockdown of individual or combinations of TCF/LEFs in PDA lines revealed TCF7L1 and TCF7L2 both function to repress β-catenin-activated reporter activity. TCF7L1 protein was also found to be targeted for rapid downregulation following Wnt pathway activation by treatment with either Wnt3A ligand or GSK3β inhibitor. RNAi knockdown of TCF7L1 in PDA lines increased anchorage-independent growth and tumor cell migration in vitro and increased in vivo PDA growth in an orthotopic xenograft tumor model. In summary, differential patterns of TCF/LEF expression are correlated with and functionally responsible for differences in Wnt pathway activation and function in PDA. Furthermore, these data implicate abrogation of TCF7L1 growth suppressive phenotypes via β-catenin-mediated downregulation of TCF7L1 as a potentially important mechanism through which Wnt signaling promotes pancreatic tumorigenesis.
Citation Format: Kathleen M. Kershaw, Michael D. Arensman, Bridgette Ho, Anna R. Lay, Nicole A. Dawson, David W. Dawson. TCF7L1 constrains Wnt/β-catenin signaling and tumor growth in pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4603.
Abstract 4607: Mediator kinase module as a transducer of oncogenic Wnt/beta-catenin signaling
Authors: Clark Alison , Oldenbroek Marieke , Wang Yao , Spaeth Jason , Gao Fangjian , Jin Victor X. , Boyer Thomas 
Published: July 2016

Abstract
Dysregulation of Wnt/β-catenin signaling promotes colorectal cancer (CRC) and other types of malignancies through unprogrammed changes in gene transcription that drive tumorigenesis. CDK8 is a CRC oncoprotein whose amplification-dependent overexpression identifies a significant subset of CRC patients with poor prognosis. CDK8 kinase activity, along with Cyclin C (CycC), drives tumorigenesis by stimulating β-catenin transcriptional activity. Thus, inhibition of CDK8 kinase function offers a promising therapeutic approach for CDK8-overexpressing CRCs. CycC-CDK8, along with MED12 and MED13, compose a four-subunit “kinase” module within Mediator, a conserved multiprotein interface between gene-specific transcription factors and RNA Polymerase II. We have previously identified a network of physical and functional interactions within the Mediator kinase module critical for oncogenic Wnt/β-catenin signaling. Mechanistically, β-catenin binds directly to MED12 in Mediator, thus activating CycC-dependent CDK8 kinase activity and β-catenin transcriptional activity. More specifically, MED12-dependent CDK8 activation occurs through a direct interaction involving the MED12 N-terminus and a phylogenetically conserved surface groove on CycC. Here, we demonstrate that mutagenic disruption of the MED12/CycC interface in CRC cell lines leads to uncoupling of CycC-CDK8 to MED12 and core Mediator, and concomitant loss of Mediator-associated CDK8 activity. Transcriptome analysis of cells lacking CDK8 kinase function revealed downregulation of Wnt/β-catenin signaling and other oncogenic pathways, consequently impairing CRC cell proliferation and clonogenicity. Our studies therefore identify the MED12/CycC interface as a critical transducer of oncogenic Wnt/β-catenin signaling. By validating MED12/CycC as a potential therapeutic target, our findings have significant implications in current methods of treating CRC as they pave a way for development of novel, targeted inhibitors of Wnt/β-catenin signaling to treat colorectal and other CDK8-driven driven malignancies.
Supported by MH085320-05 (TGB), RP140435 (TGB) and T32DE14318 (ADC).
Citation Format: Alison Clark, Marieke Oldenbroek, Yao Wang, Jason Spaeth, Fangjian Gao, Victor X. Jin, Thomas Boyer. Mediator kinase module as a transducer of oncogenic Wnt/beta-catenin signaling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4607.
Abstract 4623: Reevaluation of the role of Notch signaling in melanoma tumor development, melanoma cell survival and drug resistance
Authors: Mikheil Dareen , Rodriguez Carlos , Jayanthi Ashika , Yarlagadda Prithvi , Setaluri Vijaysaradhi 
Published: July 2016

Abstract
Notch is one of the simplest signaling pathways that is required for almost every cell type in the body. It plays several roles such as cell fate decision, differentiation and stem cell maintenance. Notch signaling plays a role in the maintenance of melanoblasts and melanocyte stem cells of the epidermis by preventing their apoptosis. Notch signaling has also been implicated in different aspects of melanoma biology including tumor initiation, progression and metastasis. Accordingly, Notch has been targeted for melanoma therapy both in preclinical xenograft models as well as clinical trials. Notch inhibitors, mainly γ-secretase inhibitors, have been widely used for this purpose. However, clinical trials with these agents have not been proven to be highly effective for melanoma treatment. In previously published studies we showed that Notch signaling is involved in regulation of melanoma trans-differentiation, a prognostic feature in primary melanoma. In this study, we reevaluated the role of Notch in melanoma development, cell survival and sensitivity to BRAF and MEK inhibitors. First, our preliminary data using the BRAFV600E/Pten mouse model showed that topical application of γ-secretase inhibitor DAPT delays tumor formation and growth. In several early passage metastatic human melanoma cell lines, we found that Notch receptors (Notch 1-3) are highly upregulated compared to normal epidermal melanocytes. Interestingly, mRNA levels for Notch1-3 receptors in normal melanocytes were either higher or comparable to their levels in the cell lines. This suggested that Notch receptor levels are tightly regulated in normal melanocytes by post-transcriptional mechanisms. Presence of cleaved Notch intracellular domain (NICD), both cytoplasmic and nuclear, in melanoma cells, but not in melanocytes, indicated constitutive activation of Notch signaling in melanoma cells. However, inhibition of Notch activation by treatment with γ-secretase inhibitor had no significant effect on survival of melanoma cells in vitro. Thus, Notch signaling appears to be dispensable for melanoma cell survival. Additionally, inhibition of Notch activation did not alter the sensitivity of melanoma cells to BRAF(V600E) and MEK inhibitors. Our results highlight the need for re-examination of Notch-regulated melanoma trans-differentiation as a therapeutic outcome.
Citation Format: Dareen Mikheil, Carlos Rodriguez, Ashika Jayanthi, Prithvi Yarlagadda, Vijaysaradhi Setaluri. Reevaluation of the role of Notch signaling in melanoma tumor development, melanoma cell survival and drug resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4623.
Abstract 4648: Uncover novel drug combinations for triple negative breast cancer
Authors: Costa Carlotta , Dastur Anahita , Peterson Rachel , Leah Damon , Egan Regina , March Ryan , Benes Cyril , Engelman Jeffrey 
Published: July 2016

Abstract
Therapeutic options for triple negative breast cancers (TNBC) are limited to multiple lines of chemotherapy with no FDA-approved targeted therapies. In the absence of a clear driver oncogene, the most common molecular alterations, including EGF receptor and genes involved in cell cycle, DNA repair and the PI3K pathway, may represent new therapeutic opportunities in TNBC. Indeed clinical benefits from PARP, EGFR and PI3K inhibitors have been reported in some TNBC patient. However, none of these studies have demonstrated durable responses, indicating that inhibition of additional pathways might be necessary to successfully improve the clinical efficacy of targeted therapies in TNBC. To develop novel, combinatorial therapeutic approaches for TNBC we performed a pharmacological screen testing 672 unique drug combinations in multiple TNBC models. The screen identified previously known and efficacious synergies, such as between EGFR and PI3K inhibitors, supporting the validity of our data and analysis. Importantly, we also identified novel promising drug combinations that we are currently exploring.
Citation Format: Carlotta Costa, Anahita Dastur, Rachel Peterson, Damon Leah, Regina Egan, Ryan March, Cyril Benes, Jeffrey Engelman. Uncover novel drug combinations for triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4648.
Abstract 4654: A novel proteasome inhibitor, bis-Benzylidine Piperidone (RA190), control hepatocellular carcinoma effectively through inhibiting STAT3
Authors: Soong Rueyshyang 
Published: July 2016

Abstract
Hepatocellular carcinoma(HCC) is one of the most common malignancy, especially in the HBV endemic Asia area. However, there is still lack of effective chemotherapy drug to treat HCC, expect Sorafenib, tyrosine kinase inhibitor, the only FDA approved chemotherapy drug to treat HCC.
In this study, we explore the chemotherapeutic properties of a novel proteasome inhibitor, bis-Benzylidine Piperidone (RA190), and its ability to manipulate the tumor microenvironment. Unlike the marketed proteasome inhibitor Bortezomib, a chemotherapeutic drug used to treat relapsed multiple myeloma, which inhibits the 20S catalytic core of the 26S proteasome, RA190 irreversibly binds to the ubiquitin receptor RPN13/ADRM1 on the 19S regulatory cap of the 26S proteasome. RA190 inhibits proteasome function and triggers accumulation of polyubiquinated proteins, and has been shown to induce endoplasmic reticulum stress-related apoptosis in HepG2 and Hepa3B hepatoma cell lines. We also found RA190 We observed a significant apoptosis of cancer cells after treatment of RA190. These changes in cancer cell lines were caused by reduction of STAT3 activity. We also proved the treatment effect of RA190 in orthotropic HCC animal models. The initial study of this novel proteasome inhibitor demonstrates its potential as an effective HCC therapy.
Citation Format: Rueyshyang Soong. A novel proteasome inhibitor, bis-Benzylidine Piperidone (RA190), control hepatocellular carcinoma effectively through inhibiting STAT3. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4654.
Abstract 4655: Iron chelation inhibits mTORC1 signaling in tumor cells
Authors: Shang Chaowei , Zhou Hongyu , Huang Shile 
Published: July 2016

Abstract
Iron chelators are commonly used for treatment of iron overload diseases. Recent studies have shown that iron chelators possess potent anticancer activities. Iron chelators (ciclopirox and 3-AP) are in clinical trials for cancer treatment. However, the molecular mechanism underlying the anticancer effect of iron chelation is not well understood. Mammalian/mechanistic target of rapamycin (mTOR) is a master kinase, regulating cell growth/proliferation and survival through sensing environmental cues. mTOR functions as at least two complexes (mTORC1/2). Here we show that two iron chelators, ciclopirox olamine (CPX) and Dp44mT, inhibit tumor cell proliferation by suppressing mTORC1 signaling in human rhabdomyosarcoma (Rh30) and lung cancer (A549 and A427) cells. This is evidenced by the findings that treatment with CPX or Dp44mT inhibited the phosphorylation of 4E-BP1 and S6K1, two best known effector molecules of mTORC1, which could be blocked by addition of ferrous sulfate. Addition of ferrous sulfate prevented the growth inhibitory effect of CPX. Ectopic expression of constitutively active mTOR also conferred resistance to CPX-induced growth inhibition. Mechanistically, iron chelation inhibition of mTORC1 was partially linked to the activation of AMPK, a negative regulator of mTORC1. Overexpression of a dominant-negative AMPK (DN-AMPK) in Rh30 cells attenuated the inhibitory effect of CPX or Dp44mT on the phosphorylation of S6K1 and 4E-BP1. In addition, iron chelation also transiently stabilized HIF-1α and further upregulated the expression of its downstream effector Bnip3, another negative regulator of mTORC1. Knockdown of Bnip3 partially attenuated the inhibitory effect of iron chelation on mTORC1. Furthermore, we found that iron chelation increased the translocation of mTOR from the cytoplasm to the nucleus. The co-localization of mTOR with the third negative regulator of mTOR, PML (promyelocytic leukemia), increased in the nucleus upon iron chelation. Moreover, iron chelation did not obviously alter the phosphorylation of IGF-1 receptor, PI3K or PTEN. The effect of iron chelation on mTORC2-mediated phosphorylation of Akt was cell line dependent. Taken together, the results suggest that the anticancer effect of iron chelation is in part related to inhibition of mTORC1 signaling, and iron chelation inhibits mTORC1 signaling via multiple mechanisms. (Supported by the FWCC, LSU Health Sciences Center)
Citation Format: Chaowei Shang, Hongyu Zhou, Shile Huang. Iron chelation inhibits mTORC1 signaling in tumor cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4655.
Abstract 4659: Folic acid-metabolizing enzymes regulate 5-fluorouracil anticancer activity on colorectal cancer cell lines
Authors: Tsukihara Hiroshi , Tsunekuni Kenta , Takechi Teiji 
Published: July 2016

Abstract
Background: In colorectal cancer chemotherapy, the current standard of care includes 5-fluorouracil (5-FU) and leucovorin (LV) combination therapy. To understand the role of folic acid-metabolizing enzymes in the LV-mediated enhancement of 5-FU's antitumor activity, we suppressed the expression of genes related to folic acid metabolism and evaluated the resultant effect on the proliferation inhibitory effect of 5-fluoro-2′-deoxyuridine (FdUrd). Method: We downregulated the expression of thymidylate synthase (TS), folate receptor 1 (FOLR1), methylenetetrahydrofolate reductase (MTHFR), methylenetetrahydrofolate dehydrogenase (MTHFD), dihydrofolate reductase (DHFR), and phosphoribosylglycinamide formyltransferase (GART) by lipofection of small interfering RNA (siRNA) in DLD-1 and HCT116 cells, and calculated the relative change in IC50 values on 48 hr exposure to FdUrd in comparison with the corresponding IC50 values in control siRNA-treated cells. In cells with TS downregulation, LV-mediated enhancement of sensitivity to FdUrd was also evaluated. Sensitivity to FdUrd was determined using the crystal violet staining method. Results: Treatment with siRNA downregulated the expression of folic acid-metabolizing enzymes. LV enhanced the sensitivity to FdUrd in control siRNA-treated cells in a dose-dependent manner. However, in cells with TS downregulation, LV did not enhance the sensitivity to FdUrd. Downregulation of folic acid-metabolizing enzymes, except TS, decreased the efficacy of FdUrd, although there was little decrease in FdUrd efficacy owing to MTHFR downregulation. Conclusion: The level of TS expression determined the LV requirement, and downregulation of folic acid-metabolizing enzymes, which impaired the folic acid cycle, decreased the efficacy of 5-FU. Comparison of the IC50 values in target siRNA-treated cells and control siRNA-treated cells.DLD-1 cellsHCT116 cellsexpression (%)*IC50 (μM)fold changeexpression (%)*IC50 (μM)fold changeNon-silencing Control siRNA100.000.671.00100.000.251.00TS10.580.010.0114.840.030.12FOLR19.148.6512.9125.122.5910.36MTHFR25.441.432.1348.750.883.52MTHFD9.662.734.0715.061.997.96DHFR8.524.146.1817.231.706.80GART18.905.388.037.102.469.84Values are means (n = 3). *: Expression (%) is the expression at the beginning of FdUrd treatment (at 48 hr after siRNA treatment).
Citation Format: Hiroshi Tsukihara, Kenta Tsunekuni, Teiji Takechi. Folic acid-metabolizing enzymes regulate 5-fluorouracil anticancer activity on colorectal cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4659.
Abstract 4675: Synergistic effect of pacritinib with erlotinib on JAK2-mediated resistance in epidermal growth factor receptor mutation-positive non-small cell lung cancer
Authors: Ochi Nobuaki , Isozaki Hideko , Takeyama Masami , Singer Jack W. , Yamane Hiromichi , Honda Yoshihiro , Kiura Katsuyuki , Takigawa Nagio 
Published: July 2016

Abstract
Patients with non-small cell lung cancer (NSCLC) harboring activating mutations in the epidermal growth factor receptor (EGFR) benefit from treatment with EGFR tyrosine kinase inhibitors (TKIs). However, almost all of the patients eventually develop resistance to EGFR-TKIs within approximately one year. The resistance mechanisms of EGFR-TKIs have not been fully elucidated. We previously established an erlotinib-resistant NSCLC cell line named PC-9/ER3 after continuously exposing PC-9 cells, which harbor an in-frame deletion in EGFR exon 19, to erlotinib. PC-9/ER3 cells were 136-fold more resistant to erlotinib than the parental cells. Although the PC-9/ER3 cells did not carry the T790M mutation or MET amplification and had similar levels of pSTAT3, pJAK2 increased in the resistant cells (Cancer Sci 103, 1795-802; 2012). Meanwhile, pacritinib is a novel macrocyclic pyrimidine-based JAK2/FLT3 inhibitor with clinical activity in patients with myelofibrosis and lymphoma, which will be used as a standard therapy for myelofibrosis. In this study, we evaluated the synergistic effect of pacritinib combined with erlotinib on JAK2-medatited EGFR-TKI resistant NSCLC.
Drug sensitivity was determined using an MTT assay and the combination index was calculated according to the methods based on the median-effect analysis. The combination of pacritinib with erlotinib showed synergistic effects on JAK2-medated EGFR TKI-resistant PC-9/ER3 cells in some cases. Western blotting showed that the combination treatment markedly suppressed pAKT and pERK although pSTAT3 was equivalent regardless of treatment with the pacritinib, erlotinib, pacritinib plus erlotinib, or control in PC-9/ER3 cells. Receptor tyrosine kinase array profiling demonstrated that pacritinib suppressed MET in the PC-9/ER3 cells. The combined treatment of pacritinib and erlotinib in PC-9/ER3 xenografts showed more tumor shrinkage compared with each drug as monotherapy. Western blotting revealed that pMET in the tumor samples was inhibited. These results suggest MET suppression by pacritinib may play a role in overcoming the EGFR-TKI resistance mediated by JAK2 in the PC-9/ER3 cells.
In conclusion, pacritinib combined with EGFR-TKI might be a potent strategy against JAK2-mediated EGFR-TKI resistance.
Citation Format: Nobuaki Ochi, Hideko Isozaki, Masami Takeyama, Jack W. Singer, Hiromichi Yamane, Yoshihiro Honda, Katsuyuki Kiura, Nagio Takigawa. Synergistic effect of pacritinib with erlotinib on JAK2-mediated resistance in epidermal growth factor receptor mutation-positive non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4675.
Abstract 4686: Intermittent exposure to EGFR tyrosine kinase inhibitors selects less EGFR T790M mutant clones than continuous exposure in lung cancer cell lines
Authors: Lee Youngjoo , Kim Kyoung-Yeon 
Published: July 2016

Abstract
Background: Drug-resistant cell lines are essential tools for investigating the mechanisms of resistance to molecular-targeted anti-cancer drugs. However, little is known about how to establish clinically relevant drug-resistant cell lines. Our study examined the impact of a drug-free period on the establishment of a cell line with clinically relevant resistance to molecular-targeted drugs.
Methods: We used PC-9 cells, a lung cancer cell line carrying EGFR mutation, because this is a validated target for EGFR tyrosine kinase inhibitors (TKI). PC-9 cells were intermittently or continuously exposed to increasing concentrations of gefitinib (0.01 μM to 1.0 μM) and the emergence of the most common acquired resistance mutation in EGFR, T790M, was determined.
Results: T790M was detected at a 25-fold lower drug concentration in cells continuously exposed to gefitinib (PC-9/GRc) than in cells intermittently exposed to gefitinib (PC-9/GRi) (0.04 μM vs 1.0 μM, respectively). The mutation frequencies at those drug concentrations were 19.8% and 8.0% in PC-9/GRc and PC-9/GRi cells, respectively. After drug-free culture for 8 weeks, resistance to gefitinib decreased in the PC-9/GRi cells but not in the PC-9/GRc cells. In the PC-9/GRc cells, the frequency of the T790M mutation was consistently about 20% from 0.04 μM to 1.0 μM of gefitinib. In the PC-9/GRc cells, the T790M mutation was detected in all single-cell clones, at frequencies ranging from 7.0% to 37.0%, with a median of 19.5% (95% confidence interval, 17.3%-20.9%).
Conclusion: Intermittent exposure to EGFR-TKIs reduces the emergence of the EGFR T790M mutation in a lung cancer cell line.
Citation Format: Youngjoo Lee, Kyoung-Yeon Kim. Intermittent exposure to EGFR tyrosine kinase inhibitors selects less EGFR T790M mutant clones than continuous exposure in lung cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4686.