bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2642: Dietary intake is associated with tumor suppressor DNA methylation in head and neck squamous cell carcinomas
Authors: Arthur Anna E. , Colacino Justin A. , Duffy Sonia A. , Dolinoy Dana C. , Terrell Jeffrey E. , Sartor Maureen A. , Chepeha Douglas B. , McHugh Jonathan B. , Bradford Carol R. , Wolf Gregory T. , Carey Thomas E. , Peterson Karen E. , Rozek Laura S.
Published: August 2012

Background: Diet is associated with prognosis in several cancers, including head and neck, and has been hypothesized to influence epigenetic state by determining the availability of moieties involved in the modification of DNA and histone proteins. Tumor DNA methylation patterns are also hypothesized to be a prognostic factor in cancer, however, the link between diet and HNSCC tumor DNA methylation has not been characterized. Methods: Pretreatment data on usual food and nutrient consumption was collected via food frequency questionnaire (FFQ) on 49 cases identified through the UM Head and Neck SPORE. Tumor DNA methylation was assessed with the Illumina Goldengate Methylation Cancer Panel, which measures methylation at 1505 CpG sites across 807 genes related to cancer. To identify if dietary intake was associated with stochastic methylation in tumor suppressor genes, we calculated a “methylation score,” the sum of the individual hypermethylated tumor suppressor associated CpG sites. Gene specific analyses using linear modeling coupled with an empirical Bayes method of variance estimation were conducted to identify if methylation at individual CpG sites is associated with dietary intake. Results: Intake of antioxidant and methyl donor nutrients tended to be inversely associated with tumor suppressor methylation score. Individuals reporting the highest quartile of dietary folate, vitamin B12 and cruciferous vegetable intake, compared to those with lowest intake, had significantly less tumor suppressor gene methylation (p=0.04 and p=0.01, respectively), as did patients reporting the highest intake of cruciferous vegetables (p=0.04). In gene specific analyses, HPV positive individuals with the highest quartile of vitamin B12 intake were found to have significantly decreased methylation of four genes, RARB, PTHLH, SNRPN, and DCC. Conclusions: These preliminary results suggest that dietary intake may influence the tumor DNA methylation profile in HNSCC and that intake of specific micronutrients may enhance tumor suppression and possibly contribute to survival. Further studies will be needed to explore the effect of diet on head and neck cancer prevention and treatment.

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 2642. doi:1538-7445.AM2012-2642
Abstract 2645: Genomic deletions and point mutations in the STK11 gene in Peutz-Jeghers Chilean families
Authors: Orellana Paulina , Alvarez Karin , Heine Claudio , Suazo Cristobal , Pinto Eliana , Carvallo Pilar , López-Kostner Francisco
Published: August 2012

Background: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant hereditary disease characterized by mucocutaneous pigmentation and gastrointestinal hamartomatous polyposis. Individuals with PJS are at increased risk for development of various neoplasms. The genetic susceptibility for PJS has been associated with germline mutation in the serine/threonine kinase 11 (STK11) gene. The aim of the present study was to characterize the genotype and phenotype of Chilean PJS patients. Methods: Mutation screening of 13 patients from 8 PJS families was performed by using single strand conformation polymorphism (SSCP) analysis and DNA sequencing, covering the entire coding region and the splice-site boundaries. In addition, multiplex ligation-dependent probe amplification (MLPA) assay was used for the identification of large exonic deletions or duplications. Results: We identified seven different pathogenic mutations in STK11 gene in 7 unrelated families. Point mutations correspond to a small deletion (c.109delC) in exon 1 that generates a premature stop codon and two intronic mutations localized in splice site of intron 4 (c.597+2 T>A) and intron 6 (c.862-2 A>G). The pathogenic effect on splicing of intronic changes was demonstrated in mRNA of STK11 from lymphocytes of patients. By MLPA, we identified four large deletions ranging from one exon to the whole gene. Breakpoints were identified in two of these patients. Three point mutations (43%, 3/7) may be considered as novel. Conclusions: Different germline mutations in STK11 were detected. A combination of sensitive techniques may improve a high STK11 mutation detection frequency (88%) in PJS Chilean families. Funded by Clinica Las Condes

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 2645. doi:1538-7445.AM2012-2645
Abstract 2646: Genetic determinants of PAH-DNA adduct level and nucleotide excision repair among non-smokers in a high risk area for esophageal squamous cell carcinoma
Authors: Etemadi Arash , Islami Farhad , van Schooten Frederik-Jan , Phillips David H. , Godschalk Roger , Golozar Asieh , Kamangar Farin , Fazel-Tabar Akbar , Pourshams Akram , Boffetta Paolo , Abnet Christian C. , Malekzadeh Reza , Dawsey Sanford M.
Published: August 2012

Background: Polycyclic aromatic hydrocarbons (PAHs) play a role in esophageal squamous cell carcinoma in high risk areas where even non-smokers are highly exposed to these compounds. Their early biological effect is the formation of DNA adducts, mediated by phase 1 and 2 pathways and nucleotide excision repair (NER). We aimed at finding a genetic model to explain inter-individual variations in PAH-DNA adduct level among people with similar exposures. Methods: In 111 randomly-selected female non-smokers from the Golestan Cohort Study in Iran, 21 SNPs in 14 genes related to xenobiotic metabolism and 13 SNPs in 9 DNA repair genes were studied (Table). NER capacity was evaluated by a comet assay, and DNA adduct level was measured by 32p-postlabelling. Multivariate regression was used to assess the effects of the number of risk alleles, NER capacity, and environmental exposures on the log-transformed PAH-DNA adduct levels. Models were compared by Akaike's information criterion (AIC). Results: Mean PAH-DNA adduct level was 5.76+3.13 per 108 nucleotides (range: 1.71 - 18.57). The level of PAH-DNA adducts was significantly lower in homozygotes for N-acetyltransferase 2 (NAT2) slow alleles and excision repair cross-complementing (ERCC)-5 T/T genotype, and higher in individuals with myeloperoxidase (MPO) G/G genotype. The sum of risk alleles in these genes had a significant correlation with the log-adduct level (r=0.4, p<0.001). The table shows gene level coefficients for multivariate analysis. The model including environmental exposures, phase 1 SNPs and NER capacity had the best fit (AIC=93.7). NER capacity itself was affected by a polymorphism in the methylenetetrahydrofolate reductase gene. Conclusion: We observed a high level of PAH-DNA adducts with great inter-individual variation, which could be best explained by a combination of environmental factors, number of polymorphisms in phase 1 genes and DNA repair capacity.

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 2646. doi:1538-7445.AM2012-2646
Abstract 2647: Influence of quercetin-rich foods intake on microRNA expression in EAGLE lung cancer tissues
Authors: Lam Tram K.
Published: August 2012

Background: Lung cancer is one of the most common cancers worldwide and has the highest cancer-related mortality rate. Dietary factors may contribute to lung carcinogenesis. Epidemiologic studies, including the Environment and Genetics in Lung Cancer Etiology (EAGLE) study, have reported increased consumption of quercetin-rich foods to be inversely associated with lung cancer incidence. Although experimental studies suggest that quercetin might affect microRNA (miRNA) expression, this mechanism has not been fully examined. We investigated this hypothesis in quercetin-related lung carcinogenesis using lung cancer tissues. Methods: miRNA expression data were derived from formalin-fixed paraffin-embedded tissue samples in 264 lung (144 adenocarcinoma and 120 squamous cell carcinoma) cases from EAGLE using a custom-made, two-channel oligo array. Quercetin-rich foods were derived from food frequency questionnaire. Individuals were categorized into high and low consumers based on sex-specific tertiles of quercetin-rich food intake. We compared the expression of miRNAs (n=198) between lung cancer cases consuming high-versus-low quercetin-rich food intake using multivariate ANOVA test. We identified miRNAs whose expression differentiated high and low consumption (p-value<0.05), and further grouped them based on their biological function using MiRBase release 17.0. miRNA families were analyzed using Functional Class Scoring (FCS). All analyses were conducted for adenocarcinoma and squamous cell carcinoma separately. Further analyses included stratification by smoking status (former and current smokers only). Results: We found that miRNA expression of 56 miRNAs significantly distinguished lung cancer cases who consumed high-versus-low quercetin-rich foods in tumor tissue within smoking-specific histological subtypes (p-value<0.05). FCS analyses of these miRNAs identified the let-7 family to strongly differentiate between high-versus-low quercetin-rich cases (p-value<0.001), followed by miR-146, miR-125, miR-26, and miR-17 (p-value<0.05). Conclusions: We observed differential expression of key biologically functional miRNAs between high-versus-low consumers of quercetin-rich foods. Our findings, the first of this kind, warrant confirmation from larger studies.

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 2647. doi:1538-7445.AM2012-2647
Abstract 2696: Modulation of intracrine androgen signaling in bone metastatic castrate resistant prostate cancer (bmCRPC) by MDV3100
Authors: Efstathiou Eleni , Titus Mark , Tsavachidou Dimitra , Wen Sijin , Hoang Anh , Ashe Robynne , Karlou Maria , Berman Craig , Troncoso Patricia , Mohler James , Logothetis Christopher J.
Published: August 2012

Background Androgen signaling is a central driver in CRPC. We performed a study to determine the effect of the antiandrogen MDV 3100 on bone marrow infiltrating CRPC. Methods From February 2010 to June 2011, we performed an open-label, observational study of 60 bmCRPC patients (pts), who underwent transilial bone marrow biopsy (BMB) at baseline and 8 weeks of treatment. Pts received MDV3100 160mg orally once daily. The primary objective was to evaluate androgen signaling in bone marrow infiltrating cancer and testosterone in blood (BT) and bone marrow (BMT) and correlate findings with clinical observations. Androgen receptor (AR), CYP17 and phospho Src (pSrc) expression were assessed by immunohistochemistry, and BT and BMT by liquid chromatography mass spectrometry. Findings Maximal PSA decline of Δ50% occurred in 29 (48%) of 60 pts, and α90% in 13 (22%). Tumor involvement in BMB was detected in 28 (47%) pretreatment BMBs. Paired tumor infiltrated BMBs were found in 23 (38%) pts. Pretreatment androgen signaling and pSrc tumor expression is shown in Table 1. Pretreatment intense nuclear AR expression combined with α10% CYP17 tumor expression or increased BMT correlate with Δ50% PSA decline (p value 0.02). AR subcellular localization shift from dominant nuclear to cytoplasmic correlate with Δ50% PSA decline (p value 0.05). Increased pretreatment p-Src expression is associated with lack of PSA decline (p value 0.002). Increase in BMT and BT is observed after 8 weeks of MDV3100. (Mean Pretreatment BMT 0.03 ng/ml, Wk8 BMT 0.04 in 33pts, p value 0.0009) (Pretreatment BT 0.05, wk8 BT 0.066 in 37 pts, p value 0.0001) Interpretation Pretreatment expression profile is consistent with persistent androgen signaling in bmCRPC. MDV3100 induces ‘pharmacodynamic’ changes in Androgen Signaling. AR changes likely account for the reported therapeutic effect of MDV3100. These data prompt exploratory combinations of MDV3100 with Androgen Biosynthesis Inhibitors and src inhibitors.

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 2696. doi:1538-7445.AM2012-2696
Abstract 270: Compensatory and non-compensatory alterations in LNCaP gene expression following antisense therapy directed against bcl-2
Authors: Rubenstein Marvin , Hollowell Courtney MP , Guinan Patrick
Published: August 2012

Antisense oligonucleotides (oligos) have been employed against in vivo and in vitro prostate cancer models targeting proteins associated with growth and programmed death (apoptosis). In LNCaP cells we evaluated monospecific (directed towards bcl-2) and bispecific (directed towards bcl-2 and the epidermal growth factor receptor [EGFR]) oligos which targeted and comparably suppressed the expression of bcl-2, an apoptosis inhibitory protein. Antisense oligos directed against bcl-2 are entering clinical trials and it was of interest to see: 1) Whether such therapy would produce non-specific effects which could compromise its’ efficacy; and 2) To identify genes whose activity, if diminished, may have to be either maintained or replaced for this type of therapy to be effective. Cells were evaluated for the expression of non-targeted genes associated with apoptosis (caspase-3, clusterin); androgen regulation (androgen receptor [AR], p300), cytokines (IL-2, IL-4, interferon [IFN]); antigen expression (prostate specific antigen [PSA], prostate specific membrane antigen [PSMA], prostatic acid phosphatase [PAP]); and autocrine growth (insulin like growth factor [IGF1]). As expected in this type of specific gene therapy, most non-targeted proteins were unaffected. However, the expression of several non-targeted genes were altered. Following the suppression of bcl-2 activity by both mono- and bispecific oligos, LNCaP cells compensated by both suppression of caspase-3 activity (an apoptosis promoter) and enhanced expression of both AR and its’ p300 co-activator. This suggests both an ability to reverse the effects of bcl-2 suppression on apoptosis through decreased expression of the apoptosis promoter and a possible stimulation of growth due to increased androgen sensitivity. It also identifies caspase-3 as an essential gene whose expression must be either maintained or replaced when bcl-2 activity is therapeutically suppressed. Among the differentiation antigens, cell surface PSMA expression was increased by bispecific oligos, whereas secretory PSA and PAP were unchanged. This PSMA increase was associated with an increased IFN expression induced by a unique double strand conformation (intrastrand hybridization) of the bispecific oligos not seen in the monospecific oligo. Increased PSMA expression could make LNCaP cells more recognizable to cytotoxic T cells and/or potentiate prostate cancer vaccines. If gene therapy is truly to be effective, the mechanisms for compensatory changes which contribute to tumor resistance must be further identified and controlled.

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 270. doi:1538-7445.AM2012-270
Abstract 2705: In search of a cost effective sentinel node biopsy technique: A randomized trial comparing the use of methylene blue and patent blue violet to identify sentinel node in breast cancer
Authors: vuthaluru seenu , Srivastava Anurag , Misra Mahesh
Published: August 2012

One of the most significant breakthroughs in breast cancer management in recent times has been in the area of sentinel lymph node biopsy (SLNB), which is now an established staging technique for assessing regional lymph node status while minimizing the morbidity associated with conventional axillary lymph node dissection. Recommended technique of SLNBis the combination of blue dye (isosulfan blue or patent blue violet) and radiotracer. However, neither of the blue dyes are currently marketed in India & are expensive. Thus, SLNB technique as practiced in the West is unlikely to be used widely in economically less developed nations. In India, some surgeons use methylene blue (MB) for identification of sentinel node in breast cancer with variable success rates. However, there are no large randomized trials comparing the efficacy of MB vis a vis isosulfan blue or patent blue violet (PBV) in identifying sentinel node in literature Objective To compare the sentinel node (SN) identification rate using patent blue violet (PBV) and methylene blue (MB) in combination with radiotracer in breast cancer. Sample size Assuming that MB identified SN in 60% cases and PBV in 85% of cases, a two group continuity corrected X2 test with 0.05 two sided test will have 80% power to detect the difference when the sample size is 57. Inclusion criteria Clinically axillary lymph node negative (N0) patients with breast cancer with tumor (T) stage T1, T2, Tx. willing to participate TechniqueCombination technique. Sentinel node: Any LN that is blue/ hot/ hot and blue is defined as SN. Any lymph node to which a blue stained lymphatic leads/ends will also be considered as SN. Results Study Period: Feb 2010-Nov 2011 No of Pts: 102 Age range: 31-82 yrs (mean: 41.4 yrs) Menopausal Status: Pre: 46 Post: 56 Side: R:L:: 50:52 T status: T1: 34; T2: 64; Tx SN identification rates: PBV: 46/49 MB: 51/53 (p value: NS) Conclusions Sentinel node can be identified with equal success rates using MB & PBV. Methylene blue can be used as a cost effective sentinel node biopsy technique in breast cancer in economically less developed countries

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 2705. doi:1538-7445.AM2012-2705
Abstract 2788: GTx-230: an orally available novel tubulin inhibitor that disrupts tumor vasculature and displays single-agent antitumor efficacy in multidrug-resistant prostate cancer with less neurotoxicity
Authors: Ahn Sunjoo , Li Chien-Ming , Barrett Christina M. , Chen Jianjun , Li Wei , Lu Yan , Miller Duane D. , Dalton James T.
Published: August 2012

A novel indole antimitotic compound, GTx-230, was identified in cell-based screening assays that binds to the colchicine site in tubulin and destabilizes microtubules. In this study, the pharmacokinetics, antitumor efficacy, neurotoxicity, and vascular disrupting ability of GTx-230 were evaluated. GTx-230 inhibited the in vitro growth of a number of human cancer cell lines including DU-145, LNCaP, PC-3, and PPC-1 prostate cancer cells with low nanomolar IC50 values. Following a 10 mg/kg intravenous (i.v.) dose to mice, the plasma clearance (CL), volume of distribution at steady state (Vdss), and terminal half-life (T1/2) of GTx-230 were 19 ml/min/kg, 2.9 l/kg, and 1.7 h, respectively. Oral bioavailability of GTx-230 was 36% in mice. In vivo, GTx-230 (6.7 mg/kg, qd, p.o.) was effective with near 100% tumor growth inhibition in xenograft models using PC-3/TXR cells over-expressing P-glycoprotein. In contrast, docetaxel, a known antimitotic agent, was not effective in the PC-3/TXR xenograft model. In vivo studies of mouse performance on an accelerating rotarod and hotplate showed that GTx-230 did not induce any symptoms of peripheral neuropathy. In addition, we evaluated the effect of GTx-230 on in vitro vascular permeability using a transwell system with confluent HUVEC monolayers. GTx-230 resulted in increased permeability after 1 h incubation and showed potency similar to CA4. In summary, the potent in vitro and in vivo antitumor activities of GTx-230 suggest that it may represent a new antimitotic agent for management of solid malignancies, particularly for patients with drug resistant 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 2788. doi:1538-7445.AM2012-2788
Abstract 2789: Interaction of (+)-discodermolide-Taxol hybrids with microtubules
Authors: Yang Chia-Ping H. , Sugasawa Keizo , Atasoylu Onur , Smith Amos B. , Horwitz Susan B.
Published: August 2012

Taxol and discodermolide are both microtubule stabilizing agents that bind to the β-tubulin subunit of microtubules. Based on our results that the hydrophobic binding pocket of β-tubulin is occupied by the Taxol side chain but not by (+)-discodermolide, and that the two drugs act synergistically in cancer cell lines, a small library of (+)-discodermolide-Taxol hybrids was synthesized (J. Med. Chem. 54:6319, 2011). Cytotoxicity assays demonstrated a 2-9-fold increase in antiproliferative activity by the hybrids compared to discodermolide in the human cancer cell lines, A549 and MCF-7. Hybrids containing a tether of 3 carbons that connect discodermolide with the Taxol side chain, exhibited the best activity. Tubulin assembly assays were performed with the two most potent hybrid molecules. Like discodermolide, these two hybrids increased tubulin assembly rapidly without a lag period. Tubulin polymerization studies using purified bovine brain tubulin demonstrated that they also had the greatest effect on the formation of polymerized microtubules. These results also were observed in intact A549 cells and in 100,000 x g supernatants prepared from these cells. We have previously shown that [3H]2-(m-azidobenzoyl)Taxol photolabels a peptide containing amino acid residues 217-231 of β-tubulin. A 5-fold molar excess of unlabeled compound inhibited the photolabeling of purified bovine brain tubulin by 94%, demonstrating the specificity of this photolabeling. Microtubule stabilizing agents (MSAs), such as Taxol, epothilone B, discodermolide and ixabepilone, each at a 5-fold molar excess, inhibited the photolabeling by 24%, 92%, 100% and 41%, respectively, indicating that discodermolide is the most potent inhibitor of the photolabeling. In contrast, two other MSAs, laulimalide and peloruside that are known to bind to a different site in β-tubulin, exhibited stimulatory effects on the photolabeling. Both drugs, at a 5-fold molar excess, increased the labeling by 30-40%. [3H]2-(m-azidobenzoyl)Taxol (0.5 - 20 µM) was used to study the kinetics of the inhibitory effects of the hybrid molecules on photoaffinity labeling of tubulin. Discodermolide-Taxol hybrids inhibited the photolabeling of bovine brain tubulin in a dose dependent manner. The concentrations that inhibited by 50% were lowest for the two most potent hybrid molecules. Therefore, the tubulin polymerization activity and the binding affinity of the hybrids to β-tubulin correlated with their antiproliferative activity. Other biological properties of the discodermolide-Taxol hybrids including senescence and antitumor activity are being evaluated.

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 2789. doi:1538-7445.AM2012-2789
Abstract 2790: Localization of the binding site for Peloruside A and Laulimalide on beta-tubulin by physical and biological means
Authors: Begaye Adrian , Trostel Shana , Taylor Richard E. , Schriemer David C. , Sackett Dan L.
Published: August 2012

Peloruside A (Pel) and laulimalide (Laul) are microtubule-stabilizing natural products that were discovered recently compared to more established agents such as the taxanes and the epothilones. The activities of Pel and Laul are synergistic with taxanes or epothilones but not with each other, indicating separate binding sites and distinct mechanisms for Pel and Laul compared to taxanes and epothilones. Hence the location and nature of the Pel / Laul binding site is of interest. We have identified this site by a physical method (mass spec H-D footprinting) and a biological one: isolating Pel-resistant mutants of human ovarian carcinoma cells (A2780 (1A9)). Four Pel-resistant lines were obtained with single-base mutations in class I β-tubulin which resulted in the following substitutions: R306H, Y340S, N337D, and A296S in various combinations. The mutations localize to the peptides identified by the mass spec method, and center on a cleft in which modeling indicates that the Pel and Laul side chains dock. The site is accessible from the outside of the microtubule and does not overlap the Taxol site on β-tubulin. The Pel resistant lines are cross resistant to Laul, but not to any other microtubule stabilizing drug, and show no cross-sensitivity to microtubule destabilizing drugs.

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 2790. doi:1538-7445.AM2012-2790
Abstract 2798: Cytotoxic and cystostatic properties of rapamycin are due to differential effects on the phosphorylation of mTORC1 substrates S6 kinase and 4E-BP1
Authors: Yellen Paige , Chatterjee Amrita , Saqcena Mahesh , Salloum Darin , Preda Angela , Rodrik-Outmezguine Vanessa , Feng Jiangnan , Xu Limei , Foster David A.
Published: August 2012

The mammalian target of rapamycin (mTOR) has been widely implicated in signals that promote cell cycle progression and survival in cancer cells. Rapamycin, which inhibits mTOR with high specificity, has consequently attracted much attention as an anti-cancer therapy. Used clinically at nano-molar concentrations, rapamycin suppresses phosphorylation of mTOR complex 1 (mTORC1) substrate S6 kinase and has been considered a cytostatic drug. However, we have reported that higher (micro-molar) doses are required for complete cell cycle arrest. Such high doses suppress phosphorylation of another mTORC1 substrate, eukaryotic initiation factor 4E (eIF4E) binding protein-1 (4E-BP1). In this state, eIF4E is sequestered and unable to facilitate mRNA translation. Dual ablation of S6 kinase and eIF4e resulted in a larger increase in G1 content than by ablation of S6 kinase alone. This confirmed the complete cytostatic effect of high-dose rapamycin. We also demonstrated that the differential dose effects of rapamycin correlate with partial and complete dissociation of Raptor from mTORC1 at low and high doses, respectively. Therefore, high-dose rapamycin ensures complete non-functionality of mTORC1. Interestingly, in the absence of serum, high dose rapamycin induces apoptosis and dual inhibition of S6 kinase and eIF4e does not prevent it. We have established that the differential cytostatic and cytotoxic effects of rapamycin are due to intact TGFb signaling. In serum, TGFb is activated upon low dose rapamycin (suppression of of S6 kinase phosphorylation). The lack of TGFb in the absence of serum allows cells to progress through the cell cycle; at high rapamycin doses, the inactivity of eIF4e results in cell death. This study reveals the mechanism for both cytostatic and cytotoxic properties of rapmaycin.

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 2798. doi:1538-7445.AM2012-2798
Abstract 2803: GSK3 plays a crucial role in determining cell response to mTOR inhibitors
Authors: Koo Junghui , Yue Ping , Tao Hui , Ramalingam Suresh S. , Khuri Fadlo R. , Sun Shi-Yong
Published: August 2012

The mammalian target of rapamycin (mTOR) exerts a critical role in the regulation of cell growth and cell survival, primarily through forming two complexes with raptor (mTOR complex 1; mTORC1) or rictor (mTOR complex 2; mTORC2). The mTOR axis is dysregulated in many types of human cancers, thus becoming an attractive cancer therapeutic target. Accordingly, mTOR inhibitors including the conventional allosteric inhibitors (rapamycin and its analogs; rapalogs) and novel mTOR kinase inhibitors (e.g., INK128) have been developed. However, single-agent activity of these inhibitors in the majority of cancer types is limited or modest at best. Thus, it is crucial to identify determinants that impact cell response to mTOR-targeted cancer therapy. In this study, we found that inhibition of GSK3 with both a small molecule inhibitor (e.g., SB216765) and gene knockdown substantially antagonized the suppressive effects of mTOR inhibitors (e.g., rapamycin and INK128) on the growth of cancer cells, including G1 arrest. In agreement, activation of GSK3 by expressing a constitutively activated form of GSK3[[Unsupported Character - Symbol Font ]] sensitized cells to mTOR inhibitors. Moreover, higher basal levels of GSK3 activity from 14 lung cancer cell lines were significantly associated with better cell responses to both rapamycin and INK128 (P < 0.05). These data together indicate that GSK3 plays a critical role in determining cell response to mTOR inhibitors. Interestingly, GSK3 inhibition did not alter the effects of mTOR inhibitors on suppression of mTOR signaling and cap-dependent translation, but rescued downregulation of cyclin D1 and c-Myc caused by mTOR inhibitors, suggesting that mTOR inhibitors decrease cyclin D1 and c-Myc levels independent of inhibition of mTOR-mediated protein translation. Instead, we found that inhibition of mTOR (e.g., by INK128) decreased the stabilities of both cyclin D1 and c-Myc. Moreover, inhibition of proteasome (e.g., with MG132) prevented cyclin D1 and c-Myc reduction by INK128. Hence it is apparent that mTOR inhibition facilitates cyclin D1 and c-Myc degradation, leading to reduction of cyclin D1 and c-Myc. Together, these findings suggest a novel mechanism by which mTOR signaling positively regulates the stability of cyclin D1 and c-Myc. Our current findings thus warrant further investigation of the potential impact of GSK3 inhibition on the efficacy of mTOR inhibitors in the clinic. (This study was supported by the Georgia Cancer Coalition Distinguished Cancer Scholar award and NIH/NCI R01 CA118450. SS Ramalingam, FR Khuri and SY Sun are Georgia Cancer Coalition Distinguished Cancer Scholars)

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 2803. doi:1538-7445.AM2012-2803
Abstract 2825: Regorafenib and Sorafenib induce reversible quiescence in human hepatoma cells
Authors: Carr Brian I. , Messa Caterina , Cavallini Aldo , D'Allesandro Rosalba , Refolo Maria Grazia , Lippolis Catia , Tafaro Angela
Published: August 2012

The actions of the multikinase inhibitor Sorafenib (Soraf) and its more potent fluoro-analog, Regorafenib (Regoraf) were examined on human Hep3B and PLC/PRF/5 hepatoma cells in vitro. IC50 was 7.5 µM for Soraf and 5.0 µM for Regoraf. Both agents required 48 hr. exposure to cells for maximal growth inhibitory effects measured by MTT at 96 hr. Evidence was found for Regoraf-induced apoptosis (max. 25% by FACS at 48 hr. and 45% decrease in Bcl-2 and BcL-xL), non-classical autophagy (50% increase in Beclin-1, without change in LC3 I/II ratio) and cell signaling changes (decreased p-ERK, increased p-JNK and p-Jun). In addition to growth inhibition, quiescence was observed for up to 6 wk. in the presence of prolonged drug exposure. Furthermore, after 1 wk. of drug-mediated inhibition, removal of either Soraf or Regoraf resulted in normal cell proliferation (recovery), unlike treatment with TGFβ 1µM or doxorubicin 0.1µM for 48 hr., after which no recovery was seen. The data are consistent with multiple mechanisms and pathways being altered during Regoraf-mediated growth inhibition and the induction of both quiescence and recovery after withdrawal of either Soraf or Regoraf, which have clinical implications.

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 2825. doi:1538-7445.AM2012-2825
Abstract 2827: In vivo effects of ICA-1 on breast cancer and glioma xenografts
Authors: Acevedo-Duncan Mildred E.
Published: August 2012

High grade breast cancer and gliomas are highly lethal tumors for which novel therapies are necessary. PKC-iota (PKC-α), an atypical protein kinase C isoform confers resistance to drug-induced apoptosis in cancer cells (J. Biol. Chem. 272; 44: 27521-27524). This research focuses on the in-vivo effects of the novel PKC-α inhibitor [1H-imidazole-4-carboxamide, 5-amino-1-[2,3-dihydroxy-4-[(phosphonooxy) methyl] cyclopentyl]-[1R-(1α, 2α, 3 β, 4 α)] (ICA-1; The Inter. J. Biochem. & Cell Biol. 43:784-794) on breast cancer and glioma xenografts. ICA-1 targets a unique sequence (amino acid residues 469-475) in the catalytic domain of PKC-α. The breast cancer xenograft study evaluated 12 athymic nude mice while the glioma xenograft study was comprised of 6 female athymic nude mice. The breast cancer xenografts were divided into saline control (n= 4) and xenografts injected with ICA-1 (20mg/kg; 5 μM; every other day, n = 8). The six glioma nude mice were divided into two groups consisting of saline controls (n = 3) and xenografts injected with ICA-1(80 mg/kg; 20 μM; every other day) when the tumor reached 100 mm3 on day 5 post implantation (n = 3). MDA-MB-468 breast cancer cells were injected subcutaneously (2 x106 cells/ flank in 0.2 ml PBS) while the human glioblastoma cell line U-87 MG was also injected into different mice subcutaneously in the right flank (1x106 cells/flank in 0.1 ml PBS). Tumor volume was calculated using formula: length x width x width x ½. Results showed that ICA-1 prevented glioma tumor growth even after stopping dosing at day 9 and continuing to monitor tumor growth for an additional nine days. Glioma tumor volume in these ICA-1 treated mice decreased by 51% compared to controls. ICA-1 was also effective in decreasing breast cancer xenograft growth by 50%. The weight of either ICA-1 treated breast cancer or glioma xenograft mice did not decrease compared to controls. These results indicate that ICA-1 is effective in preventing the growth of breast cancer and glioma xenografts. Future studies will establish toxicity data and optimize the dose and frequency of ICA-1 treatment for potential anti-PKC-α therapy.

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 2827. doi:1538-7445.AM2012-2827
Abstract 2828: Characterization of protein substrates of PSA: effect of PSA stimulating peptides
Authors: Mattsson Johanna , Hekim Can , Närvänen Ale , Jonsson Magnus , Malm Johan , Stenman Ulf-Håkan , Koistinen Hannu
Published: August 2012

Increased proteolytic activity is associated with cancer, where proteases play a major role in tumor spread and formation of metastases. However, proteases may also inhibit tumor growth. The prostate produces several proteases, the most abundant one being prostate-specific antigen (PSA or kallikrein-related peptidase-3, KLK3). The role of PSA in the prostate, and in particular in prostate cancer, is not well known. However, several functions have been proposed, most of which are based on the protein substrates, which PSA cleaves in vitro. These include both tumor growth promoting and inhibiting activities, e.g., antiangiogenic activity of PSA. We have previously used phage display technology to develop peptides, the synthetic analogs of which stimulate the activity of PSA. These peptides are useful for studying the significance of PSA-activity and potentially for prostate cancer treatment. We analyzed the cleavage of different protein substrates of PSA and found that physiological substrates, semenogelin-1 and −2, are cleaved much more efficiently than other substrates, such as IGFBP-3, fibronectin and galectin-3. The peptides increased the proteolytic activity of PSA towards these protein substrates, but the extent of stimulation and the relative efficiency of peptides were different than with small peptide substrates. We conclude that the peptides can be used to stimulate the activity of PSA towards natural protein substrates. Thus, they may be potential lead molecules for drug development. As most of the studied protein substrates are cleaved with very low efficiency, their relevance as PSA substrates is questionable, especially as prostate produces several other highly active proteases, including several kallikreins and trypsin. As compared to other substrates, semenogelins are very efficiently cleaved by PSA, highlighting the substrate specificity of PSA.

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 2828. doi:1538-7445.AM2012-2828
Abstract 2831: Studies on the mechanistic basis of the anticancer activity of 2,4-disulfonyl-PBN (OKN-007)
Authors: Floyd Robert A. , Chandru Hema , Stewart Charles , Towner Rheal A.
Published: August 2012

Sulfatase 2 (Sulf2) is a protein which resides in the extracellular matrix of cancer cells and enzymatically removes sulfate from the 6-O-sulfate esters of heparin. Several tumors have been shown to be enriched in Sulf2 in comparison to normal tissues where it is either absent or present at very low levels. The action of Sulf2 alters growth factor binding to the extracellular matrix of cells and has been shown to be important in the development of many cancers including breast, lung, liver, colon, and pancreas. Sulf2 mobilizes fibroblast growth factors (FGFs), vascular endothelial growth factor (VEGF) and stromal derived growth factor-1 (SDF-1) bound to heparin. We found that OKN-007 acts to weakly inhibit the aryl sulfatase activity of Sulf2 acting on the substrate 4-methylumbelliferyl-sulfate (4-MUS) and to more effectively inhibit the enzymatic activity of Sulf2 when it acts upon its natural substrate the 6-O-sulfate ester of heparin. The Sulf2 enzymatic activity was potently inhibited by suramin, a compound that has 6 phenyl-sulfonyl groups as part of its chemical structure and has been shown to have anti-cancer activity. Utilizing the natural substrate we have shown that other sulfonyl-phenyl compounds act to suppress the activity of Sulf2. We have conducted preliminary studies to see if OKN-007 has anti-cancer activity in a breast cancer mouse xenograph model. Balb/c female ovariectomized Estradiol pellet-implanted nude mice were implanted with MCF-7 breast cancer cells and OKN-007 was administered at 250mg/kg/day in the drinking water. The experiment was terminated at week 5 at which time the data showed that OKN-007 decreased the average tumor volume by 33%. OKN-007 has been shown to have anti-cancer activity in the rat C6 model of glioma. The anti-cancer mechanism of action of OKN-007 is still unknown. Recently we have explored the potential of OKN-007 to alter cancer cell migration in a gradient involving the chemokine SDF-1 and its cellular receptor CXCR4. The CXCL4/SDF-1 gradient is considered to be important in the metastasis of primary cancers. Results with rat C6 glioma cells, U87MG human glioma cells as well as MCF-7 breast cancer cells indicate that OKN-007 at low concentrations inhibits cancer migration in a CXCR4/SDF-1 gradient. These observations need to be explored in more depth utilizing animal models of cancer metastasis. Research supported in part by US Army Concept Grant W81XWH-09-1-0352. Dr. Floyd holds the Merrick Foundation Chair in Aging Research.

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 2831. doi:1538-7445.AM2012-2831
Abstract 2838: High-throughput genotoxicity screening unlocks chemotherapeutic potential of antioxidants
Authors: Myung Kyungjae
Published: August 2012

Human ATAD5 is a biomarker for identifying genotoxic compounds because ATAD5 protein levels increase post-transcriptionally in response to DNA damage. We screened over 4,000 compounds with a novel, cell-based quantitative high-throughput ATAD5-luciferase assay detecting genotoxic compounds. We identified 22 antioxidants, including resveratrol, genistein, and baicalein, that are currently used or investigated for the treatment of cardiovascular disease, type 2 diabetes, osteopenia, osteoporosis, and chronic hepatitis, and for anti-aging. Treatment of dividing cells with these compounds induced DNA damage and resulted in cell death. Despite their genotoxic effects, resveratrol, genistein, and baicalein did not cause mutagenesis, which is a major side effect of conventional anti-cancer drugs. Furthermore, resveratrol and genistein killed multi-drug resistant cancer cells. We therefore propose that resveratrol, genistein, and baicalein are attractive candidates for improved chemotherapeutic agents.

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 2838. doi:1538-7445.AM2012-2838
Abstract 2855: SRC represents a potential therapeutic target in liposarcoma
Authors: Sievers Elisabeth , Trautmann Marcel , Kindler Dagmar , Pedeutour Florence , Aman Pierre , Nishio Jun , Wardelmann Eva , Büttner Reinhard , Hartmann Wolfgang
Published: August 2012

Liposarcomas (LS) represent the most common malignant soft tissue tumors in adults. Therapeutic outcome of LS is mainly determined by the efficiency of surgery as a high tendency for local relapse is seen. Chemo- and radiotherapy represent further therapeutic options, however, specifically targeted therapies are currently not available. The oncoprotein SRC is a tyrosine kinase, which has been shown to be activated in a variety of human cancers. SRC activation plays an important role in cancer cell proliferation, survival, angiogenesis and motility. In this work we analyzed LS biopsies comprising the main different subgroups, i.e. myxoid (MLS), well/dedifferentiated (WDLS/DDLS) and pleomorphic (PLS) LS and corresponding cell lines regarding SRC activation and studied the biological effects of SRC inhibition. Based on data derived from phospho-kinase screens in LS cells, immunhistochemical stainings of (Tyr416)-phosphorylated (p)-SRC were performed in primary LS biopsies. LS cell lines treated with the SRC inhibitor dasatinib were analyzed for phosphorylation of SRC and its downstream signaling molecules, cell proliferation, migration and apoptosis. Furthermore, synergistic effects of simultaneous treatments with dasatinib and conventional cytotoxic drugs were investigated. Particularly WDLS/DDLS and MLS tumor cells showed a significant expression of p-SRC. In LS cell lines, inhibition of SRC with dasatinib resulted in a substantially impaired cellular growth accompanied by a decreased phosphorylation of SRC and its downstream targets. Flow cytometric analysis showed that effects of SRC inhibition were due to an increase in apoptosis (cleaved PARP(Asp 214)) and a decrease of cellular proliferation (phospho-(Ser10) Histone H3). Scratch and Boyden chamber assays indicated a diminished migratory potential of the tumor cells due to SRC inactivation. Simultaneous treatment of liposarcoma cell lines with dasatinib and chemotherapeutic drugs resulted in additive effects. Our data suggest that SRC kinase activation represents an important biological feature of LS which might be successfully addressed in targeted therapeutic approaches.

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 2855. doi:1538-7445.AM2012-2855
Abstract 2871: Inhibition of androgen receptor-mediated expression of prostate derived ets transcription factor (PDEF) induces a loss of prostate cancer cell differentiation
Authors: haller Andrew C. , Li Fengzhi
Published: August 2012

While inhibition of androgen signaling has shown to extend the lives of many patients, there is a growing concern in the field that androgen ablation may select for a more aggressive and lethal phenotype of prostate cancer. It has long been known that androgen receptor (AR) mediates growth and cellular differentiation. Therefore, inhibition of AR may stem cancer growth, but concurrently cause cells to de-differentiate and gain migratory and invasive properties. Prostate derived ets transcription factor (PDEF) is an AR target gene highly expressed in normal prostate tissue and has shown to be sufficient to mediate terminal epithelial cellular differentiation in the lung and colon. Previous studies in our lab have demonstrated, through retrospective IHC staining of FFPE radical prostatectomy specimens, loss of PDEF expression significantly associated with increased incidence and patients’ shorter metastatic free survival time with early stage prostate cancer. Furthermore, previous studies in the literature have detected the PDEF promoter sequence through AR ChIP-Sequencing and ChIP-on-ChIP experiments. We therefore studied the regulation of PDEF expression by AR as a potential mediator of prostate epithelial cellular differentiation. Our data indicated that anti-androgens, androgen starvation or AR shRNA was sufficient to abrogate PDEF protein and mRNA expression. Stable expression of AR shRNA or PDEF shRNA by lentiviral infection displayed a coordinate decrease in e-cadherin expression and an increase in vimentin expression, indicating a potential shift to a mesenchymal-like phenotype. This epithelial-to-mesenchymal transition was also observed in cells acutely treated with anti-androgens bicalutamide or finasteride. Together, these results demonstrate that androgen ablation therapy may directly drive cells to de-differentiate and gain migratory/invasive capabilities, and therefore should only be indicated for those patients with a very short life expectancy or co-existing morbidities.

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 2871. doi:1538-7445.AM2012-2871