bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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 &gt;5 fold more sensitive to pemetrexed than H1975 cells (H460 IC50 = 200nM; H1975 IC50 = &gt;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&lt;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

Abstract
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 &lt; 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

Abstract
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
Abstract 47: Cancer-associated fibroblasts mediate extracellular matrix remodeling and three-dimensional invasion of scirrhous gastric carcinoma cells
Authors: Yamaguchi Hideki , Yanagihara Kazuyoshi , Yashiro Masakazu , Sakai Ryuichi 
Published: August 2012

Abstract
Scirrhous gastric carcinoma (SGC; also called diffusely infiltrative carcinoma, Borrmann's type-IV carcinoma, or the linitis plastica-type carcinoma) have the worst prognosis among various types of gastric cancer, owing to highly progressive invasion, frequent metastasis to lymph nodes, and high incidence of peritoneal dissemination. SGC cells rapidly and diffusively infiltrate through the submucosa without forming obvious tumor mass and induce extensive stromal fibrosis, resulting in thickening and stiffening of the gastric wall. Because histophathological analyses have shown that massive proliferation of stromal fibroblasts occur within lesions of SGC, cancer-associated fibroblasts (CAFs) have been proposed to support the progression of SGC. However, biological and molecular basis of the interaction between SGC cells and CAFs remains largely unknown. In this study, we investigated the roles of CAFs in invasion and extracellular matrix (ECM) remodeling by SGC cells. When 44As3 SGC cells were co-cultured with CaF37 SGC-derived fibroblasts on 3D Matrigel, they formed large cell aggregates that invade into the Matrigel. Other SGC cell lines, HSC59 and HSC44PE, but not differentiated non-SGC gastric caner cell lines, MKN7, MKN1, and MKN74, formed invasive cell aggregate with CaF37 cells. Time-lapse imaging of SGC and CaF37 cells, and of fluorescent microsphere embedded in the Matrigel revealed that this process is associated with extensive contraction and remodeling of ECM. In order to further characterize the ECM remodeling activity of CAFs, we cultured 44As3 and CaF37 cells on fluorescent gelatin-coated coverslips. CaF37 cells caused disruption of the gelatin matrix and this activity was further promoted by co-culturing them with 44As3 cells. Immunoblotting and immnofluorescence analyses revealed that phosphorylation of myosin light chain was significantly increased in CaF37 cells co-cultured with 44As3 cells. Finally, a myosin II inhibitor blebbistatin blocked the three-dimensional invasion and ECM remodeling by 44As3 and CaF37 cells. These results indicate that SGC cells promote actomyosin-mediated contractility of stromal fibroblasts to remodel ECM during 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 47. doi:1538-7445.AM2012-47
Abstract 470: Motility of human colorectal cancer cells is promoted by H1047R kinase mutation of PI3K p110-alpha
Authors: Wan Guanghua , Ongchin Melanie , Hand Essence , Rajput Ashwani 
Published: August 2012

Abstract
INTRODUCTION: Mutations in the catalytic subunit p110α of Class 1A phosphatidyinositol 3-kinase (PI3K) occur in nearly 1/3 human colorectal cancer (CRC). In vivo studies have demonstrated that cell lines bearing the p110α mutation are more metastatic than wild type PI3K cells. The most frequent cancer-specific mutations in p110α are the kinase domain mutation H1047R and the helical domain mutation E542K/E545K. Our group has previously shown that the two hotspot mutations in PI3K in either the helical or kinase domains have a significantly different metastatic potential in an orthotopic murine model. The aim of this study was to compare the difference in cell motility between the helical and kinase domain mutation bearing human CRC cell lines. METHODS: Wound healing Assay was used to determine the motility of human CRC cells in vitro. Effect of PI3K inhibition on cell motility was tested under the treatments with 0.1 and 1.0 µM of wortmannin, which is a class 1 PI3K inhibitor, and PIK75, which is the specific inhibitor of p110α. RESULTS: Our data indicate that H1047R-p110α increases cell motility more than E545K-p110α and the inhibition of PI3K significantly delayed or abrogated the migration of CRC cells. Immuno-blotting analysis showed increased downstream survival signaling pathway activation of PI3K in the cells bearing H1047R-p110α knase domain mutation compared to the cells which have E545K-p110α helical domain mutation. CONCLUSION: The PI3K-p110α kinase mutation bearing CRC cells were more motile as compared to the helical domain mutation bearing cells. This data supports our previous in vivo data that kinase domain mutations have a greater metastatic capability than helical domain bearing mutants. Cell motility was abrogated by both nonspecific and p110α directed PI3K inhibition suggesting that the activation of PI3K is necessary for CRC cell motility. This data supports the efforts to target the PI3K pathway in patients with advanced CRC.
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 470. doi:1538-7445.AM2012-470
Abstract 4708: Short-term romidepsin treatment combined with mitogen-activated protein kinase and phosphatidylinositol 3-kinase inhibition causes increased Bim expression and cell death in KRAS mutant cell lines
Authors: Bahr Julian C. , Robey Robert , Chakraborty Arup , Luchenko Victoria , Bates Susan E. 
Published: August 2012

Abstract
Romidepsin (FK228) is a histone deacetylase inhibitor (HDI) that modulates chromatin and activates apoptotic pathways in vitro. Clinical efficacy observed in peripheral and cutaneous T-cell lymphoma has not been replicated in solid tumors, as for other HDIs. We thus sought drug combinations that might improve the activity of romidepsin in solid tumors. Mutations in KRAS induce the mitogen activated protein kinase pathway (MAPK) and the phosphatidylinositol 3-kinase (PI3K) pathway. Laboratory data have suggested that activated MEK or AKT can confer resistance to HDIs. To determine if mitogen-activated protein kinase kinase (MEK) or AKT inhibitors could increase sensitivity to romidepsin, we measured cell death by annexin assay in a panel of 20 cell lines, nine KRAS mutants and eleven KRAS wild-type (WT). Cells were exposed to 25 ng/ml romidepsin for 6 h in the presence of 250 nM MEK inhibitor PD0325901 and/or 1 µM AKT inhibitor MK2206, after which romidepsin was removed and cells were incubated with the inhibitors alone for an additional 42 h. Among the 20 solid tumor cell lines examined, those harboring a KRAS mutation had a higher percentage of cell death than lines with WT KRAS when treated with the PD0325901/romidepsin combination (46.1±18% vs. 21.6±7.6% respectively, p-value .0057), the MK2206/romidepsin combination (43.8±15.8% vs. 28.6±13.6%, respectively, p-value .0470), or the PD0325901/MK2206/romidepsin combination (66.5±14.8% vs. 35.0±18.8%, respectively, p-value .0008). There was no statistically significant difference (p-value &gt; .05) in cell death between KRAS and WT cell lines treated with any of the compounds alone. As expression of the pro-apoptotic protein Bim has been associated with romidepsin-mediated cell death, and as the MAPK pathway has been shown to phosphorylate and inactivate Bim, we examined Bim expression in cell lines sensitive to combined treatment with romidepsin and inhibitors. In the OVCAR5 cell line, which harbors a G12V KRAS mutation, we noted that romidepsin induced Bim expression and that combined treatment with PD0325901 led to higher expression by western blot. The high levels of Bim expression were associated with increased poly ADP ribose polymerase cleavage. These data demonstrate the benefit of combining an HDI with MEK and AKT inhibitors in KRAS mutant cell lines. Romidepsin and MAPK pathway inhibitor combinations should be further evaluated in patients with mutant KRAS cancers.
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 4708. doi:1538-7445.AM2012-4708
Abstract 4709: Combined mitogen-activated protein kinase pathway inhibition with short-term romidepsin treatment induces proapoptotic Bim and cell death in BRAF mutant cancers
Authors: Robey Robert W. , Luchenko Victoria L. , Bahr Julian , Chakraborty Arup R. , Zimmer Alexandra S. , Piekarz Richard L. , Bates Susan E. 
Published: August 2012

Abstract
Solid tumor trials with histone deacetylase inhibitors (HDIs) have been largely disappointing. We recently characterized a romidepsin-resistant T-cell lymphoma cell line that was found to have activation of the mitogen-activated protein kinase (MAPK) pathway, leading to subsequent phosphorylation and degradation of the proapoptotic protein Bim, suggesting that activation of this pathway may also confer resistance to romidepsin and other HDIs. The V600E BRAF mutation has been found in approximately 60% of melanomas and approximately 15% of colon cancers and leads to constitutive activation of the MAPK pathway. We thus hypothesized that combined treatment with romidepsin and BRAF or mitogen-activated protein kinase kinase (MEK) inhibitors may be effective in cancers that harbor the V600E BRAF mutation. To more closely simulate clinical administration of romidepsin, 11 V600E BRAF mutant cell lines (8 melanomas and 3 colorectal cancers) were exposed to 25 ng/ml romidepsin for 6 h after which romidepsin was removed, cells were incubated in fresh medium for an additional 42 h and subsequently apoptosis was measured by Annexin V and propidium iodide staining. Of the 11 cell lines, 10 exhibited significantly higher annexin staining after short-term romidepsin treatment (control 7.1% ± 3.8% vs. treated 34.7% ± 17.8%, p&lt;0.001). Cells were subsequently treated with medium containing 25 ng/ml romidepsin with 250 nM of the MEK inhibitors AZD6244 (selumetinib) and PD0325901 or 1 µM of the mutant BRAF inhibitor PLX4032 (vemurafenib) for 6 h, after which the cells were incubated an additional 42 h in medium containing the inhibitors alone. Combined treatment with romidepsin and AZD6244 resulted in a significantly higher percent of annexin positive cells (p&lt;0.05) in 9 of the 11 BRAF mutant cell lines examined. Immunoblot analysis demonstrated inhibition of the MAPK pathway at the concentrations used and that apoptosis was associated with increased expression of Bim, as well as increased poly (ADP-ribose) polymerase cleavage. Our results suggest that combined treatment with romidpesin and BRAF or MEK inhibitors may be useful in the treatment of cancers that express mutant BRAF.
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 4709. doi:1538-7445.AM2012-4709
Abstract 471: Acute activation of beta2-adrenergic receptor inhibits in vitro renal carcinoma cell migration through betaArrestin2-mediated regulation of p115RhoGEF
Authors: Ma Xiaojie , Zhao Yu , Daaka Yehia , Nie Zhongzhen 
Published: August 2012

Abstract
Metastatic renal cell carcinoma (RCC) is fatal with no current effective treatment. Molecular mechanisms underlying progression to metastatic RCC are not fully understood, and gene array studies have revealed increased expression of beta2-adrenergic receptors (beta2AR) and betaArrestin2 genes in RCC. We examined the regulation of RCC migration and invasion, two critical steps in the progression to the metastatic disease, following beta2AR activation using scratch assays and Boyden chamber assays in cultured RCC cell lines Caki-1, SN12C and RCC7. Acute treatment with the selective beta2AR agonist formoterol inhibited migration of the three cell lines by 40% to 70% with an IC50 of 2.5 nM or less. We further examined contribution of G protein and betaArrestin signaling. Using the betaAR-inverse agonist carvedilol that is biased for[[Unsupported Character - &#61472;]]betaArrestin signaling, combined with transient knockdown of Gs or betaArrestin2 by siRNA, or mouse embryonic fibroblasts from betaArrestin1 or betaArrestin2 knockout mice, we identified betaArrestin2 as a mediator of beta2AR-induced inhibition of cell migration. betaArrestin2 forms a complex with p115RhoGEF (guanine nucleotide exchange factor) that was previously shown to be regulated by Gq and G12/13. Activation of beta2AR promoted the translocation of p115RhoGEF to the plasma membrane, with consequent activation of RhoA which enhances formation of focal adhesions that restrain the cell migration. These results suggest that betaArrestin2 exerts cell compartment-specific effects on the cell migration. In the absence of acute beta2AR activation, betaArrestin2 sequesters p115RhoGEF in the cytosol, leading to relatively lower RhoA activity at the cell periphery and higher cell migration rate. Upon acute beta2AR activation, betaArrestin2 translocates to the plasma membrane with concomitant enrichment of p115RhoGEF at the plasma membrane, resulting in the activation of RhoA and decreased cell motility. Our results imply that betaArrestin2 and its effectors impact RCC metastasis and suggest its utility as a drug target to limit progression of the disease.
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 471. doi:1538-7445.AM2012-471
Abstract 4712: Target epigenetic regulation at a specific genomic region by using DNA binding molecules and HDACi
Authors: Nagase Hiroki , Watanabe Takayoshi , Koshikawa Nobuko 
Published: August 2012

Abstract
Pyrrole-Imidazole (PI) polyamide molecule was originally designed from structures of natural DNA binding molecule, such as Distamicine and Diocarbamicine and has been recognized as a synthetic molecule which binds the minor groove of Watson-Click base pair of double-stranded DNA in a sequence-dependent manner. We hypothesized conjugates between this synthetic DNA binding molecule and Histone Deacetylase inhibitor (HDACi) of Suberoylanilide hydroxamic acid (SAHA) should regulate histone acetylation in a specific region of the genome. We have taken two strategies to confirm this hypothesis. One is the candidate gene approach and another is chemical library approach. We synthesized a PI polyamide targeted the p16INK4a tumor suppressor gene and also synthesized a library of sequence-specific PI polyamides conjugated with the potent HDAC inhibitor, termed PIP-SAHA and screened their effect on the expression of tumor suppressor genes and Yamanaka factors, respectively. Chromatin immunoprecipitation analysis revealed SAHA-PIP induce acetylation of Histone H4 and H3 in the promoter region of p16, Oct-4 and Nanog. SAHA-PIP showed significant induction against c-Myc, Oct-3/4, Sox-2, and Klf-4, respectively in MEF but did not show significant induction of tumor suppressor p16 transcription. We also confirmed only SAHA did not show such histon acetylation and transcription induction, which implicated the role of PI polyamide conjugates in the induction of histone acetylation in specific genomic regions. Furthermore, a significant change in MEF morphology was demonstrated with our hit SAHA-PIPs. Those data suggests that a capability of PIP-SAHA regulate histone modification in a genomic sequence specific manner and promote agents for reprogramming efficiency in order to generate iPSCs, although the endogenous tumor suppressor gene expression was not observed, probably by means of “double lock” epigenetic silencing of tumor suppressor gene.
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 4712. doi:1538-7445.AM2012-4712