bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2973: Differential regulation of p21waf1 protein half-life by DNA damage and nutlin-3 in p53 wild-type tumors and its therapeutic potential
Authors: Chang Li-Ju , Eastman Alan R. 
Published: June 2012

Abstract
DNA damage induces cell cycle arrest through both Chk1 and the p53 tumor suppressor protein, the latter arresting cells through induction of p21waf1 protein. Arrest permits cells to repair the damage and recover. The frequent loss of p53 in tumor cells makes them more dependent on Chk1 for arrest and survival. We have used the topoisomerase I inhibitor SN38 to induce DNA damage in three p53 wild-type cell lines: the immortalized MCF10A, and tumorigenic HCT116 and U2OS. Both phospho-Chk1 and p53 were elevated to a similar extent in all three cell lines. However, the HCT116 and U2OS cells exhibited far less accumulation of p21waf1 protein. The p21waf1 mRNA was induced to a similar extent, and the protein half-life was similar (∼ 30 min) in all three cell lines. These results suggest that the two tumor cell lines have a reduced rate of translation of the p21waf1 mRNA. To obtain further insight into the regulation of p21waf1, we incubated the three cell lines with the non-genotoxic drug nutlin-3, which disrupts p53:MDM2 binding thereby inducing a p53 response. Nutlin-3 induced similar levels of p53 in the three cell lines, and these levels were comparable to those seen with SN38. While nutlin-3 had little additional impact on p21waf1 induction in MCF10A cells and the half-life remained at ∼ 30 min, there was a much stronger induction in HCT116 and U2OS cells which was attributed to a much longer protein half-life (∼ 80 to 90 min). Incubation of p53 mutant cells with Chk1 inhibitors such as SCH900776 can overcome SN38-induced cell cycle arrest and drive cells through a lethal mitosis. p53 wild-type cells can be protected from this lethal mitosis through induction of p21waf1. However, the defective p21waf1 induction in HCT116 and U2OS cells is insufficient to protect them from Chk1 inhibition. In contrast, incubation with nutlin-3 induced sufficient p21waf1 that the cells arrested in either G1 or G2. This arrest protected the cells from subsequent incubation with the S phase-specific DNA damaging agents SN38 and hydroxyurea, either alone, or when combined with checkpoint inhibition. This protection was not observed in MCF10A or HCT116 cells deleted for p21waf1, or in MDA-MB-231 cells that have mutant p53. The results demonstrate that some p53 wild-type tumors have defects in p21waf1 expression, and may retain sensitivity to a combination of DNA damage plus checkpoint inhibition. Furthermore, the results suggest nutlin-3 could be used to protect normal cells from these combinations such that therapy can be targeted selectively to p53-defective tumors.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2973. doi:10.1158/1538-7445.AM2011-2973
Abstract 2986: Partial inhibition of Plk1 is cytotoxic despite normal spindle structure
Authors: Lera Robert F. , Burkard Mark E. 
Published: June 2012

Abstract
Polo-like kinase 1 (Plk1) is a multifunctional mitotic kinase that has emerged as an attractive target for cancer chemotherapy. Frequently over-expressed in tumors, Plk1 is absent in the surrounding non-proliferating tissue. Furthermore, Plk1 depletion in tumor cell lines produces monopolar spindles and mitotic arrest that ultimately leads to cell death. However, it is unclear whether monopolar spindles mediate cytotoxicity at physiologic drug concentrations. We used a chemical genetic system to test the effect of partial inhibition of Plk1 in human cells. We discovered that partial inhibition of Plk1 produces a cytotoxic response in the absence of a prolonged mitotic delay. We hypothesized that partial inhibition disrupts mitosis via alternate mechanisms from the archetypal monopolar spindle-induced prometaphase arrest. We performed time-lapse microscopy experiments after exposure to low (0-1 μM) and high (10 μM) concentrations of the ATP analog, 3-MBPP1. As expected, 90% (53/60) of untreated cells successfully completed mitosis, whereas all cells (28/28) treated with 10 μM exhibited a monopolar-spindle induced prometaphase arrest. Surprisingly, 29-40% of cells treated with 3-MBPP1 exhibited a transient prometaphase delay, followed by impaired anaphase segregation and frequent cytokinesis failure. Indirect immunofluorescence demonstrates aberrations in chromosome and microtubule dynamics, which we are further characterizing. Partial inhibition of Plk1 leads to cytotoxicity by a spindle-independent mechanism. These results are important for developing Plk1-targeted therapies. First, they demonstrate that continuous dosing of an oral Plk1 inhibitor is likely to act by a different mechanism from intermittent high doses of an intravenous drug. Second, partial inhibition may provide a more physiologically relevant background to study function of kinase inhibitor activity in the treatment of cancer. Finally, identification of the responsible substrate may reveal the most sensitive biomarker for kinase inhibition in patient samples.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2986. doi:10.1158/1538-7445.AM2011-2986
Abstract 2989: Integrin-linked kinase regulates mitotic spindle dynamics and its overexpression leads to resistance to paclitaxel-induced cell death
Authors: Lim Simin , Fielding Andrew B. , Kawamura Eiko , Dedhar Shoukat 
Published: June 2012

Abstract
Dysregulated mitosis is a hallmark of cancer. Many centrosomal proteins, including the integrin-linked kinase (ILK), that regulate microtubule organization and mitotic spindle assembly have been implicated in cancers. Inhibition or depletion of ILK result in a mitotic spindle defect that has not been well characterized and while ILK is overexpressed in many cancers, the effect of ILK overexpression on mitotic spindle function is unknown. In this study, we have characterized the defective spindle phenotype, and also looked at the effect of ILK overexpression on mitotic spindle function. HeLa cells stably over-expressing wild-type ILK were used for overexpression studies while parental HeLa cells were treated with QLT-0267, an ILK-specific inhibitor, to study the defective spindle phenotype. While ILK inhibition led to an abnormal mitotic spindle phenotype, the spindle contained bona fide kinetochore-microtubules that persisted after cold- or calcium-treatment. ILK inhibition, however, led to higher sister-centromere stretch in chromosomes aligned between two spindle poles, suggesting that kinetochores were under abnormally high tension, likely due to inhibition of microtubule polymerization. Microtubule regrowth in mitotic cells after cold depolymerization was significantly slower with ILK inhibition. In the context of ILK overexpression in cancers, we first measured the duration of mitosis and showed that ILK-overexpressing cells completed mitosis at a faster rate and also required shorter durations between metaphase and anaphase. ILK overexpression also resulted in increased resistance to paclitaxel-induced cell death. Collectively, our data suggest that ILK regulates microtubule dynamics, which is the focus of ongoing investigations in our laboratory, and ILK overexpression has clinical implications by inducing resistance to paclitaxel, possibly through increased microtubule dynamics.
This work was supported by funding from the Canadian Institutes of Health Research.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2989. doi:10.1158/1538-7445.AM2011-2989
Abstract 2994: Constitutional telomere length correlates with colorectal cancer (CRC), but varies by age of cancer onset
Authors: Boardman Lisa A. , Johnson Ruth A. , Skinner Halcyon G. , Seo Songwon , Gangnon Ronald , Litzelman Kristin , Engelman Corinne , Thibodeau Stephen N. , Petersen Gloria M. , Cunningham Julie M. 
Published: June 2012

Abstract
Introduction: Short constitutional telomere length is associated with aging and cancer, but the correlation of telomere length and age at diagnosis of CRC has not been evaluated. Methods: We measured telomere length using quantitative PCR of peripheral blood leukocyte DNA in 1026 individuals diagnosed with MSS CRC who were ≤60 years of age and were chemo-radiotherapy naïve at the time of blood draw. We compared telomere length with 1972 unrelated healthy controls who were frequency matched for gender and age at time of blood collection. We used constructed percentiles of telomere length using the data from the controls. Results: Overall, regardless of cancer status, there was a weak negative correlation of telomere length with age such that as age increased telomere length decreased (Pearson correlation coefficient =−0.1, p&lt; 0.0001); and men had shorter telomeres than women (p=0.0002). The odds ratio (OR) for MSS CRC increased with longer telomere length (OR 1.62 [CI: 1.31-1.99] for those with telomere lengths in the 90th percentile compared to those with telomere lengths in the 50th percentile. In multivariate analysis with adjustment for gender, BMI, smoking, alcohol, and diabetes, telomere length remained an independent risk factor for CRC (p&lt; 0.001), with interaction between telomere length and age (≤50, longer telomeres increased CRC risk; &gt; 50 years old, increasing telomere length associated with decreased CRC risk). Risk was higher for MSS CRC ≤50 years for patients with telomere lengths in the 90th percentile compared to those in the 50th percentile (OR 2.31; CI:1.65-3.23). For subjects diagnosed 50-60 yrs, longer telomere length was associated with lower risk of CRC, and shorter telomere length was associated with the development of CRC (OR 1.22 for telomere lengths in the 10th percentile compared to those in the 50th percentile (OR 1.22:CI; 1.05-1.43). Conclusion: Telomere dynamics appear to influence MSS CRC risk and may differ on the basis of age of cancer diagnosis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2994. doi:10.1158/1538-7445.AM2011-2994
Abstract 3000: MIIP regulates histone H3 phosphorylation at serine 10 and securin degradation during mitosis in colon cancer cells
Authors: Ji Ping , Hu Limei , Zhang Wei 
Published: June 2012

Abstract
Chromosome condensation and segregation are highly orchestrated during mitosis. In early mitosis, dramatic structural changes occur to produce metaphase chromosomes, each consisting of a pair of compacted sister chromatids (condensation), At anaphase onset, a signal is produced to disrupt the linkage between sister chromatids (segregation), allowing them to be pulled apart to two daughter cells. Recently, we discovered that the MIIP protein, encoded by the Migration and invasion inhibitory protein gene located on chromosome 1p36, plays a critical role in mitotic transition through negatively regulating APC/CCdc20 activity and stabilizing cyclin B1 in glioma cells. Here we report that MIIP inhibits chromosome condensation and segregation resulting in G2/M arrest and polyploidy cell formation in colon cancer cells. Gain-of-function studies showed that the MIIP expression inhibited colony formation of isogenic HCT116 cells independent of the TP53 and PUMA status. To understand the potential role of MIIP in colon cancer cells, a panel of six colon cancer cell lines (DLD1, SW620, SW480, HCT116, NCI-747 and SW837) was used to elevate MIIP expression by adenovirus expression vector (Ad-MIIP). The G2/M arrest and polyploidy cell formation were observed in all the six cell lines we tested irrespective of the status of microsatellite stability and TP53 mutation. By using double thymidine block strategy, we synchronized HCT116 cells at G1/S boundary and released the cells in fresh medium to enrich the cell population in different stage during the cell cycle. We found that the expression of MIIP is cell cycle dependent and peaks at mitosis. Two major mitotic regulators, cyclin B1 and securin, were induced by MIIP. The cycloheximide (CHX) chase experiments showed that MIIP blocked cyclin B1 and securin degradation, which is consistent with our previous finding that MIIP directly interacted with Cdc20 and inhibited APC/CCdc20 activity. We further found that MIIP inhibited histone H3 phosphorylation at serine 10. Taken together, our studies provide evidence that MIIP plays a critical role in chromosome condensation and segregation in mitosis. Because chromosome 1p36 region is commonly deleted in colon cancer cells, the MIIP gene may represent a novel negative cell cycle regulator that is abnormally altered thus contributing to genomic instability in colon cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3000. doi:10.1158/1538-7445.AM2011-3000
Abstract 3022: Disruption of the nuclear matrix attachment domain of the DNA replication factor Ciz1 in common solid tumors and its potential as a biomarker
Authors: Sercombe Heather , Higgins Gillian , Munkley Jennifer , Copeland Nikki , Roper Katherine , Rahman Faisal Abdel , Ainscough Justin , Coverley Dawn 
Published: June 2012

Abstract
The DNA replication protein Ciz1 promotes initiation of mammalian DNA replication in cooperation with cyclin A-dependent kinase, most likely by delivery cyclin A to sites where cyclin E-dependent pre-replication complex assembly has taken place. Normally, Ciz1 is anchored within nuclear matrix-associated foci that co-localize with sites of DNA replication, but in the absence of anchor domain Ciz1 retains the ability to promote initiation of DNA replication in isolated nuclei so attachment to the nuclear matrix is not essential for function. Here, we show that expression of DNA replication and nuclear matrix anchor domains of Ciz1 are uncoupled and uneven at the transcript level in a panel of common cancer cell lines, giving rise to excess DNA replication domain protein that is not attached to the nuclear matrix. Moreover Ciz1 domain expression is also uncoupled in a wide range of common solid tumours, including breast and lung, so that anchor domain transcript is elevated over control tissues, and exceeds replication domain in all primary stage I, II and III tumours tested. Notably, more than half of all stage IV tumours tested resemble established cell lines, having more replication domain than anchor domain. In cell based assays, recombinant anchor domain protein interferes with attachment of endogenous Ciz1 to the nuclear matrix, revealing a dominant negative effect that also impacts on nuclear matrix-recruitment of a key component of the pre-replication complex, Cdc6. This shows that Ciz1 normally plays a role in localizing Cdc6 to the nuclear matrix and suggests that cancer-associated uncoupled expression influences recruitment of mammalian pre-replication complexes to the nuclear matrix. These findings implicate spatially unconstrained DNA replication as a source of nuclear disorder in cancer cells.
We identified a variant Ciz1 isoform with alterations in nuclear matrix attachment domain and tumour-restricted expression. Variant Ciz1 is elevated at the transcript and protein level with high frequency in small cell lung tumours, and with lower frequency in a range of other tumour types. Selective suppression of variant Ciz1 expression using inducible shRNA restricts proliferation of lung cancer cells that express it in vitro and in vivo, identifying a novel, exploitable therapeutic target with potential application in the treatment of lung cancer. Recent evidence will also be presented on the application of variant Ciz1 as a serum biomarker.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3022. doi:10.1158/1538-7445.AM2011-3022
Abstract 3028: A multiplexed, bioluminescent HDAC assay for determining target-specific, anti-cancer potency
Authors: Evans Nathan , Niles Andrew L. , Kirkland Thomas A. 
Published: June 2012

Abstract
Histone deacetylase (HDAC) class I and II enzymes are zinc dependent protein deacetylases. They play many roles in normal gene regulation events of development and homeostasis, but their dysregulation has been linked to a variety of solid tumors and hematological malignancies. We have recently developed a one-step, homogeneous, luminescent assay for activity detection from multiple HDAC Class I and II isoforms, thereby providing a useful tool for cell culture, enriched or recombinant sources of lysine deacetylases. This luciferase-containing, “glow-type” assay reagent is cell-permeable and can directly measure HDAC activity in living attachment-dependent and suspension cells. Furthermore, this luminescent HDAC assay can be paired in same well multiplex formats with fluorescent assays that measure biomarkers associated with changes in viability and cytotoxicity. Here we correlate HDAC inhibition with cellular fate using representative inhibitors from the hydroxamate, short-chain fatty acid, benzamide and cyclic peptide classes. We will also demonstrate relative on-target anti-cancer efficacies and off-target safety using transformed, primary or iPS-derived cell lineages.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3028. doi:10.1158/1538-7445.AM2011-3028
Abstract 3033: NKX2-5, a potential tumor suppressor gene in prostate cancer
Authors: Daremipouran Mohammad , Wang Song Ping , Ellis Alexander , Bamji Zebalda , Kwabi-Addo Bernard 
Published: June 2012

Abstract
Background: Prostate cancer (PCa) is a common malignancy and a leading cause of cancer deaths among men in the United States. Abundant evidence has accumulated to suggest that epigenetic DNA methylation changes may appear earlier during PCa development than genetic changes, as well as more commonly and consistently suggesting that DNA methylated genes can be explored as DNA-based biomarker for PCa disease detection. Recently, we have identified NKX2-5 as a novel that is hypermethylated in prostate cancer. However, there is little information about the biological significance of this gene in prostate carcinogenesis. We hypothesize that NKX2-5 is a potential tumor suppressor gene that is frequently inactivated in prostate cancer. Methods: We carried out gain-and-loss functional studies of NKX2-5 in prostate cancer cell lines and validated expression at the RNA transcript level using quantitative RT-PCR. Protein expression was analyzed by western blotting and cell cycle analysis investigated by flow cytometer. Results: Over-expression of NKX2-5 was detrimental to prostate cancer cell proliferation as evidenced by significant inhibition of prostate cancer cell proliferation in comparison to control (vector only transfection) and this was due to cell arrest in Go/G1 phase and increase apoptosis. In contract, successful knockdown of NKX2-5 by shRNA transfection increased prostate cancer cell proliferation. Western blot analysis demonstrated that NKX2-5 plays a key regulatory role in the expression of several genes including p53, PTEN, Histone H1 and the androgen receptor. Conclusion: Our observation suggests that NKX2-5, a member of the homeobox gene family of plays an important tumor suppressor activity in prostate carcinogenesis. Because this gene plays important role in several signal transduction pathways, this gene can be exploited as potential biomarker for the early detection of prostate cancer and could be an attractive target to explore for drug investigation or gene therapies of prostate cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3033. doi:10.1158/1538-7445.AM2011-3033
Abstract 3035: Functional roles of HS6ST3 in human breast cancer in vitro
Authors: Iravani Omid , Yip George W. , Bay Boon-Huat 
Published: June 2012

Abstract
Introduction: Heparan sulfate is a sulfated polysaccharide that is found on the cell surface and extracellular matrix of all human cells. It interacts with a variety of proteins and is thus involved in numerous biological processes such as growth and development. Heparan sulfate's function critically depends on the number and the position of sulfate groups, which modulate the binding sites for proteins such as growth factors, cytokines, receptors, enzymes, and inhibitors. However, little is known about their roles both in vitro and in vivo. Alterations in heparan sulfation may be associated with pathologic conditions such as cancer. Heparan sulfate 6-O-sulfotransferases (HS6STs) catalyze the transfer of sulfate groups to the carbon 6 position in heparan sulfate. Three isoforms of these enzymes have been discovered in humans. Recently, several studies have proposed that dysregulation of 6-O-sulfation patterns may be involved in carcinogenesis. This study aimed to analyze the functional role of HS6ST3 in T47D breast cancer cell line. Procedures: HS6ST3 was silenced using siRNA by more than 85%. Functional studies such as proliferation, cell cycle, apoptosis, adhesion and migration assays were then performed. Results: The study demonstrated that silencing HS6ST3 in T47D breast cancer cell line enhanced apoptosis and cellular adhesion; and diminished proliferation with cell cycle arrest at G0/G1. Taken together the results demonstrated that silencing HS6ST3 decreased the tumoral progression in breast cancer. Conclusions: This could be happen through alteration of heparan sulfate interactions with ligands such as growth factors. HS6ST3 could be used not only as a valuable biomarker for diagnostic and prognostic purposes but in cancer gene therapy in near future.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3035. doi:10.1158/1538-7445.AM2011-3035