bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 5448: An exosomal biomarker for prostate cancer
Authors: Bhagirath Divya , Yang Thao , Sekhon Kirandeep , Bucay Nathan , Majid Shahana , Hashimoto Yutaka , Kulkarni Priyanka , Dasgupta Pritha , Shiina Marisa , Shahryari Varahram , Imai-Sumida Mitsuho , Yamamura Soichiro , Tabatabai Z Laura , Tanaka Yuichiro , Dahiya Rajvir , Deng Guoren , Saini Sharanjot
Published: July 2017

Prostate tumors are highly heterogeneous and molecular characterization based on biopsy sampling is often challenging. Hence, it is desirable to have an easily accessible, minimally invasive way to determine the molecular imprints of a patient’s tumor. Exosomes in blood are an important source of non-invasive, circulating biomarkers and provide an enriched source of microRNAs. With an objective of identifying microRNA based markers, we developed a comprehensive procedure for exosomal microRNA profiling analyses from sera of prostate cancer patients employing Nanostring nCounter technology. In a pilot study, we profiled exosomal miRNAs from a training cohort of normal individuals, patients with benign prostate hyperplasia (BPH), indolent form of PCa and aggressive metastatic prostate cancer. Exosomes were extracted from serum and the integrity of exosomal preparations was confirmed by nanoparticle tracking analysis and Western blot analyses for exosomal markers CD63, CD9 and TSG101. Levels of two miRNAs were significantly upregulated and several candidate miRNAs were markedly downregulated in metastatic PCa serum samples compared with controls. The candidate microRNAs were further validated in a larger cohort by real time PCR based microRNA assays. Of significance, we validated miR-1246 as an exosomal marker for prostate cancer. miR-1246 levels were specifically altered in prostate cancer patients and not significantly altered in BPH. Our analyses suggest that miR-1246 is a promising diagnostic biomarker for prostate cancer.

Citation Format: Divya Bhagirath, Thao Yang, Kirandeep Sekhon, Nathan Bucay, Shahana Majid, Yutaka Hashimoto, Priyanka Kulkarni, Pritha Dasgupta, Marisa Shiina, Varahram Shahryari, Mitsuho Imai-Sumida, Soichiro Yamamura, Z Laura Tabatabai, Yuichiro Tanaka, Rajvir Dahiya, Guoren Deng, Sharanjot Saini. An exosomal biomarker for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5448. doi:10.1158/1538-7445.AM2017-5448
Abstract 5449: Nanoparticle delivery of miRNAs to inhibit GBM stem cells
Authors: Lopez-Bertoni Hernando
Published: July 2017

Cancer cells arise from multiple complementary genomic and epigenomic abnormalities that deregulate pathways that control cell proliferation and tissue homeostasis. Epigenetic modifications, involving deregulation of non-coding RNAs, are emerging as critical determinants of gene expression and essential drivers of neoplastic phenotypes. Our knowledge of how these complex epigenetic mechanisms operate in the context of cancer cell phenotype regulation remains limited. Non-coding RNAs, in particular miRNAs, are emerging as critical epigenetic regulators of cell fate and oncogenesis. MiRNAs act by selectively inhibiting gene expression primarily by targeting mRNA for degradation usually via complementary 3’-UTR seed sequences. Numerous miRNAs have been found to regulate tumorigenesis and cancer cell stemness by virtue of their capacity to target tumor-suppressing or tumor promoting transcripts. We recently showed that the coordinated actions of Oct4 and Sox2 induce a tumor-propagating stem-like state in GBM cells through a mechanism that involves the induction of DNMTs and down-regulation of a network of miRNAs through promoter DNA methylation. Two of the miRNAs repressed by Oct4/Sox2, miR-148a and miR-296-5p, efficiently inhibit the tumor propagating capacity of GBM stem-like, making them excellent candidates for therapeutic intervention.

Options for treating high-grade brain tumors remain limited. Recent developments in nanomedicine provide new and exciting opportunities to treat and manage brain tumors. Cationic polymers are a class of biomaterials with great promise for targeted molecular therapeutics. We combined this cutting-edge technology with our newly discovered stem cell inhibiting miRNAs to develop nano/miR conjugates to treat gliomas. We show these nano/miR conjugates distribute throughout an established tumor in vivo, and more importantly, delivering these tumor-suppressing miRNAs using PBAE polymers inhibits the growth of established GBM tumor in mouse models. Our findings demonstrate that identifying and validating stem cell-inhibitory in combination with current advances in nanomedicine will undoubtedly impact the development of novel therapies for targeting the CSC population and treating GBM.

Citation Format: Hernando Lopez-Bertoni. Nanoparticle delivery of miRNAs to inhibit GBM stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5449. doi:10.1158/1538-7445.AM2017-5449
Abstract 5453: Dysregulation of miRNAs in esophageal cancer: function and clinical implication
Authors: Sharma Rinu
Published: July 2017

Background: Growing evidence suggests importance of aberrant microRNA (miRNA) expression in development and progression of cancer. Recent studies have demonstrated the potential of miRNA panels as promising diagnostic, prognostic and predictive biomarkers.

Objective: The purpose of the present study was to evaluate the clinical and functional significance of miRNAs in esophageal cancer (EC).

Methods: Herein, we evaluated the diagnostic potential of a five miRNA panel (consisting of miR-21, miR-144, miR-107, miR-93 and miR-342) in EC detection using quantitative real time PCR (qRTPCR). To evaluate the discriminatory power of miRNA panel, receiver operating characteristic curve (ROC) curves were generated for each of the miRNAs followed by risk score analysis. Briefly, linear regression models were fitted using the cancer status and each of the risk score as input. ROC curves were then used to evaluate the diagnostic potential of the panel and to find out the appropriate cut-off point. Sensitivity and specificity of the panel were then determined. Further, pathway enrichment analysis was carried out to find the most significant pathways targeted by these miRNAs. Next, we elucidated the role of miR-144, by silencing it in KYSE-410 cells followed by MTT assay, cell cycle analysis, colony formation assay and scratch assay. Potential targets of miR-144 were predicted by in silico approach followed by in vitro validation by luciferase reporter assay.

Results: The ROC curve analysis indicated that the panel of five miRNAs (AUC=0.851, p<0.001) constitutes a more sensitive and specific diagnostic marker as compared to any of the single miRNAs. Most importantly, panel of circulating miRNAs showed enhanced sensitivity (87.5%) and specificity (90.4%) with an AUC of 0.96 (p<0.001) in discriminating EC patients from normal subjects. Inhibition of miR-144 significantly suppressed the proliferation of ESCC cells by 42.085±1.73% at 72 h post transfection. Moreover, knockdown of miR-144 decreased (p=0.046) the migration potential of KYSE-410 cells as compared to the cells treated with negative control. In silico analysis and further validation by dual-luciferase reporter assay revealed PURA to be a direct downstream target of miR-144.

Conclusion: Herein, we have demonstrated the potential diagnostic implication of five miRNA panel. Further, we have shown that mir-144 acts as an oncogenic miRNA by targeting PURA and promotes EC cell proliferation.

Citation Format: Rinu Sharma. Dysregulation of miRNAs in esophageal cancer: function and clinical implication [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5453. doi:10.1158/1538-7445.AM2017-5453
Abstract 5454: Serum circulating microRNAs as potential biomarkers for prostate cancer
Authors: Kasomva Khanmi , Savarimuthu Ignacimuthu , Paulraj Gabriel Michael , Sen Arnab , Sailo Stephen , SV Ngachan
Published: July 2017

MicroRNAs (miRNAs) are small non-coding RNA, whose differential expression has been involved in the development and progression of cancers, including prostate cancer (PCa). In recent studies circulating miRNAs have been demonstrated to have the potential as non-invasive biomarkers in various types of cancer. The aim of this study was to investigate the serum circulating miRNA-103 could be used in diagnosis of prostate cancer in North-Eastern India patient population. To evaluate this study blood samples were collected from prostate cancer patients and healthy controls following ethical approval and informed consent. The samples were reverse transcribed using stem loop primers and expression levels of miRNA-103 were determined using real time PCR. Differential expressions of miRNA-103 for each case were used to compare PCa serum with healthy serum samples. Serum circulating miR-103 levels was significantly down-regulated in the PCa patients comparison with healthy control. The serum circulating miRNA-103 could be potential for the diagnosis of PCa in North-Eastern India Population.

Citation Format: Khanmi Kasomva, Ignacimuthu Savarimuthu, Gabriel Michael Paulraj, Arnab Sen, Stephen Sailo, Ngachan SV. Serum circulating microRNAs as potential biomarkers for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5454. doi:10.1158/1538-7445.AM2017-5454
Abstract 5455: Novel miRNA-based therapeutic approach to selectively target mutant p53 in cancer
Authors: Lulla Amriti R. , Einarson Margret B. , Zhou Yan , Dicker David T. , El-Deiry Wafik S.
Published: July 2017

Tumor suppressor p53, guardian of the genome, is frequently mutated or functionally dysregulated in more than 50% of human tumors. p53 mutation is a later event in tumorigenesis and a number of p53 mutants have “Gain of Function” (GOF) properties that have been shown to promote invasive and more aggressive phenotypes in cancer cells. Mutant p53 has been an attractive and promising therapeutic target for advanced stages of tumors. Yet, mutant p53 has proved to be one of the most undruggable targets. Thus, there is continued interest in understanding the GOF properties of mutant p53 and in designing novel strategies to target mutant p53 and/or key GOF pathways. Mature MicroRNAs (miRNAs) are ~22 nt endogenous, non-coding RNA sequences that bind to 3’UTR of their target genes and inhibit their translation. miRNA mimics are emerging therapeutics and attractive tools for mapping pathway networks. We developed a novel functional high throughput screening (HTS) assay to identify miRNAs that selectively target mutant p53-expressing cell lines. The HTS was performed in isogenic TP53+/+ (wild-type), TP53-/- (null) and TP53 R175H (mutant) HCT-116 colorectal cancer cell lines. Cell viability was used as the HTS read-out of our functional screen. Of 2754 miRNA mimics screened, we identified 56 miRNAs that selectively target TP53 R175H (mutant) cells. Our ongoing work is directed to further validating and identifying which of these miRNA mimics selectively induce apoptosis in mutant p53-expressing cells. We are also using reporter-based assays to identify a fraction of the 56 miRNAs that can bind to the p53 3’UTR. Our long-term goal is to selectively target mutant p53-expressing cells using miRNA mimics as single agents or in combination with FDA-approved or experimental therapeutics. Our strategy is may provide a unique opportunity for development of targeted therapy for TP53 mutant tumors.

Citation Format: Amriti R. Lulla, Margret B. Einarson, Yan Zhou, David T. Dicker, Wafik S. El-Deiry. Novel miRNA-based therapeutic approach to selectively target mutant p53 in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5455. doi:10.1158/1538-7445.AM2017-5455
Abstract 5457: OGT restrains the NRF2 antioxidant pathway via O-GlcNAcylation of KEAP1
Authors: Chen Po-Han , Smith Timothy J. , Wu Jianli , Boyce Michael , Chi Jen-Tsan Ashley
Published: July 2017

O-GlcNAcylation is a reversible post-translational modification that adds an O-linked β-N-acetylglucosamine (O-GlcNAc) moiety onto serine/threonine residues of target proteins. This modification is regulated by only two enzymes: O-GlcNAc transferase (OGT, the writer) and O-GlcNAcase (OGA, the eraser) in mammals. Recent studies have revealed that OGT expression and O-GlcNAc modifications are elevated in several cancers, but specific O-GlcNAc targets are not well defined. We conducted a global transcriptome profiling in MDA-MB-231 breast cancer cells to search for signaling events that respond to O-GlcNAc fluctuation. We found significant up-regulation of genes involved in the NRF2-dependent stress response when OGT activity is inhibited in different tumor types. We also discovered a strong positive correlation of gene signatures between low OGT activity and NRF2 activation in multiple human tumor gene expression datasets. NRF2, the primary regulator of redox balance, is usually activated by oxidative stress and repressed under basal conditions by the KEAP1-CUL3 ubiquitin ligase complex. However, we found that OGT inhibition increases NRF2 protein level through reducing poly-ubiquitination of NRF2 in the absence of oxidative stress. By chemical sugar labeling and mass spectrometry assays, we identified that KEAP1 is directly O-GlcNAcylated by OGT especially within the BTB and Kelch motifs. Of all 11 putative O-GlcNAc sites on KEAP1, we found serine 104 is responsible for regulating NRF2 activity through affecting KEAP1-CUL3 interaction. Interestingly, we found the amount of intracellular glucose co-vary with KEAP1 O-GlcNAcylation and NRF2 protein, suggesting that glucose metabolites may utilize the nutrient sensing O-GlcNAcylation to fine-tune the antioxidant response. We propose that cancer cells could utilize O-GlcNAcylation, specifically on KEAP1, to regulate NRF2-mediated stress responses in response to the dynamics of intracellular glucose level. Since the NRF2 pathway is inappropriately activated in certain tumor types due to dysregulated function of KEAP1, such as non-small cell lung cancer, where it provides stress resistance and a growth advantage. Our study could provide new insight into redox cancer biology and provide novel strategy to modulate NRF2 activity during tumor development.

Citation Format: Po-Han Chen, Timothy J. Smith, Jianli Wu, Michael Boyce, Jen-Tsan Ashley Chi. OGT restrains the NRF2 antioxidant pathway via O-GlcNAcylation of KEAP1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5457. doi:10.1158/1538-7445.AM2017-5457
Abstract 5463: Disulfiram suppresses metastasis via induction of anoikis and calpain activation in triple-negative breast cancer
Authors: Oh Eunhye , Sung Daeil , Cho Youngkwan , Kim Ji Young , Lee Nahyun , Kim Yoon-Jae , Cho Tae-Min , Seo Jae Hong
Published: July 2017

Triple-negative breast cancers (TNBC) exhibit aggressive phenotypes and are associated with poor clinical outcomes due to a lack of effective therapeutic strategies. Disulfiram (DSF) is a clinical therapeutic drug for the treatment of alcoholism, and has also been shown to exhibit antitumor activity in TNBC cells in a copper (Cu)-dependent manner, although how this occurs has not been clearly elucidated. We sought to investigate the mechanisms responsible for DSF/Cu-dependent induction of apoptosis and suppression of lung colonization by TNBC cells. DSF/Cu treatment significantly induced apoptosis, accompanied by an increase in the sub-G1 population, as well as caspase-3 activation. DSF/Cu strongly suppressed cell migration and invasion, while inducing suppression of focal adhesion kinase (FAK) phosphorylation and focal adhesions, concomitant with an observed reorganization of cytoskeletal F-actin and collapse of the plasma membrane. These effects were associated with calpain activation, coinciding with the breakdown of vimentin, FAK and talin, presumably allowing for cell detachment. In a xenograft tumor model, DSF suppressed tumor growth and lung colonization, which was also associated with calpain activation. Taken together, these findings warrant further investigation of disulfiram as a potential treatment for metastatic TNBC.

Citation Format: Eunhye Oh, Daeil Sung, Youngkwan Cho, Ji Young Kim, Nahyun Lee, Yoon-Jae Kim, Tae-Min Cho, Jae Hong Seo. Disulfiram suppresses metastasis via induction of anoikis and calpain activation in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5463. doi:10.1158/1538-7445.AM2017-5463
Abstract 5467: Phosphoproteomic analysis of pyruvate dehydrogenase in response to environmental stress
Authors: O'Neill Wendi , Golias Tereza , Benej Martin , Denko Nicholas
Published: July 2017

Pyruvate dehydrogenase is a mitochondrial enzyme that regulates the flux of carbohydrates into oxidative phosphorylation. The activity of PDH is largely regulated by reversible phosphorylation. The pyruvate dehydrogenase kinases add inhibitory phosphorylations to PDH on the E1α subunit at positions 232, 293, and 300. Interestingly, there is a family of 4 related PDHK genes with overlapping affinity for the 3 phosphorylation sites. PDHK1 and PDHK3 have been identified as hypoxia-inducible at the transcriptional level, and PDHK1 has been shown to be important for the growth of model tumors. This work attempts to more carefully define the functions of PDHK1 and 3 using CRISPR technology in colorectal cancer lines in vitro and genetically engineered mice in vivo.

Using antibodies specific for the phosphorylated sites on E1α, we find that PDHK1 is essential for the phosphorylation of the 232 site in response to hypoxia and partially responsible for the hyperphosphorylation of 293 and 300. The level of phosphorylation in response to hypoxia is also sensitive to nutrients in the environment, with high levels of glucose enhancing E1α phosphorylation in hypoxia. Analysis of the number of phosporylations on individual E1α molecules using isoelectric focusing shows a range of events, with some molecules having 2 or 3 phosphorylations, while a large fraction of the E1α remains unphosphorylated in hypoxia. This type of pattern suggests a non-random phosphorylation of the multiple sites.

Analysis of PDH activity supports the in vitro findings that any single phosphorylation event is sufficient to inhibit PDH complex activity. Preliminary mitochondrial oxygen consumption experiments show that colorectal cancer cells are less dependent on PDHK1 for regulating mitochondrial function compared to published data in pancreatic and head and neck cancer. Finally, analysis of PDH phosphorylation in mice supports a role for PDHK1 in the regulation of PDH activity in response to fasting and blood glucose levels.

In conclusion, regulation of PDH in normal and cancerous colonocytes appears to be sensitive to environmental oxygen and nutrients. PDHK1 is the PDHK family member with the greatest influence on the addition of non-random inhibitory phosphorylation events. These in vitro findings will be analyzed with respect to the findings obtained using the new PDHK1 fl/fl villin Cre mouse.

Citation Format: Wendi O'Neill, Tereza Golias, Martin Benej, Nicholas Denko. Phosphoproteomic analysis of pyruvate dehydrogenase in response to environmental stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5467. doi:10.1158/1538-7445.AM2017-5467
Abstract 5469: Low dose ionizing radiation induces persistent activation of NADPH oxidase pathway in mouse colon
Authors: Kumar Santosh , Suman Shubhankar , Moon Bo-Hyun , Fornace Albert J. , Datta Kamal
Published: July 2017

Exposure to ionizing radiation has been linked to persistent oxidative stress. The purpose of the current study was to characterize the role of NADPH oxidase pathway in radiation-induced increased oxidant production in colon epithelial cells. Mice (C57BL/6J; 6-8 weeks, male) were exposed to either sham or 0.5 Gy γ radiation, and NADPH oxidase pathway and oxidative stress markers were assessed in colon samples 60 d after exposure. Radiation exposure led to higher elevation of 4-HNE and 8-oxo-dG staining relative to unirradiated control. We also observed increased staining for the proliferative marker phospho-histone H3 in colon sections of irradiated mice. PCR analysis showed increased expression of two NADPH oxidase isoforms, Nox1 and Nox3, in irradiated samples. Additionally, expression of NoxA1 and Noxo1 along with Hif1α were also increased after radiation. Immunoblot analysis confirmed the PCR results, and ChIP assay revealed greater binding of stress response factor GATA6 and Hif1α to Nox1 and Nox3, and Nox3 promoters respectively after radiation exposure relative to control. Co-immunoprecipitation experiments show enhanced binding of Rac1, an activator of NADPH oxidase, to Nox1 and Nox3. In summary, we demonstrated that exposure to a low dose of γ radiation caused long-term upregulation of NADPH oxidase isoforms as well as its regulators and activators such as NoxA1, Noxo1, Hif1α, TLR4, GATA6, Doux1, and Doux2. When considered along with our results on oxidative stress and proliferative markers, our observations on NADPH oxidase pathway provides new insight into molecular events contributing to radiation-induced persistent oxidative stress and cell proliferation in colon, and have implications for colorectal carcinogenesis.

Note: This abstract was not presented at the meeting.

Citation Format: Santosh Kumar, Shubhankar Suman, Bo-Hyun Moon, Albert J. Fornace, Kamal Datta. Low dose ionizing radiation induces persistent activation of NADPH oxidase pathway in mouse colon [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5469. doi:10.1158/1538-7445.AM2017-5469
Abstract 5470: Reversibility of therapy-induced senescence in non-small cell lung cancer as a model of cancer recurrence
Authors: Saleh Tareq , Cudjoe Emmanuel K. , Kyte S Lauren , Henderson Scott C. , Elmore Lynne W. , Gewirtz David A.
Published: July 2017

Disease recurrence at either primary or metastatic tumor sites arising from dormant tumors is largely responsible for the morbidity and mortality of many cancers. Although cellular quiescence has been proposed as a mechanism of dormancy, the nature of the growth arrest that allows tumor cells to re-emerge months or years after treatment has never been directly determined. The current work was designed to examine the hypothesis that the senescence induced by cancer chemotherapeutic drugs could be reversible, with implications for tumor dormancy and disease recurrence. Studies were performed using etoposide in models of non-small cell lung cancer (NSCLC). Exposure to etoposide at sublethal concentrations resulted in growth arrest accompanied by the induction of senescence and autophagy. Growth arrest was transient in that proliferative recovery was evident by day 7 post-etoposide exposure. Analysis of senescence based on β-galactosidase activity demonstrated that the restoration of proliferative capacity coincided with a decline in the extent of senescence. Real-time live microscopy demonstrated heterogeneous fates of senescent cells, where the bulk of the cell population remaining in a state of stasis, a subset of cells undergoing apoptosis, and a fraction of the large, flattened, and polyploid cells spontaneously entering into mitosis. Neither genetic nor pharmacological inhibition of autophagy influenced the senescence response to etoposide, the eventual proliferative recovery, or sensitivity to etoposide. These findings indicate that the induction and resolution of senescence is independent of the accompanying autophagy, and that the autophagy induced by etoposide is non-cytoprotective in function. These observations suggest that therapy-induced senescence may ultimately be a transient process in that at least a subpopulation of tumor cells can and will regain proliferative capacity. Consequently, therapy-induced senescence could potentially be studied as a model of tumor dormancy, and the reversibility of senescence as a model of disease recurrence.

Citation Format: Tareq Saleh, Emmanuel K. Cudjoe, S Lauren Kyte, Scott C. Henderson, Lynne W. Elmore, David A. Gewirtz. Reversibility of therapy-induced senescence in non-small cell lung cancer as a model of cancer recurrence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5470. doi:10.1158/1538-7445.AM2017-5470
Abstract 5471: LSD1 stimulates cell survival and epigenetic homeostasis via snail in hepatocellular carcinoma
Authors: Jo Yong Hwa , Nguyen Minh Nam , Choi Tae Gyu , Kim Sung Soo
Published: July 2017

HCC is the fifth most common malignancy in the world. HCC generally arises in the context of chronic liver diseases, or other metabolic, dietary or toxic factors. Hypoxia is a critical microenvironment in hepatcarcinogenesis. It occurs in series of distinct steps that include tumor cell invasion and proliferation. The process of EMT required for liver cancer cell invasion is regulated by a family of E-box-binding transcription repressors, which include Snail and Slug. Protein N, the first discovered histone methylase, is an epigenetic enzyme playing important role in regulation of gene expression and function by removing mono- or dimethyl moieties from H3K4 and H3K9. However, the molecular mechanisms underlying these biological behaviors have not been completely elucidated. Here, we present the first evidence that expression of Protein N was transcriptionally induced by Hif1 under hypoxia condition. We also showed that the up-regulated Protein N enhanced HCC cell survival and sustained epigenetic homeostasis via activating Snail under hypoxic conditions in vitro/in vivo. Furthermore, we revealed that Protein N/Snail stimulated Hif1 expression by a positive feedback loop. Conclusively, we elicited that Protein N is an essential mediator in epigenetic aberrances of HCC (This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (NRF-2016R1D1A1B03933763)).

Note: This abstract was not presented at the meeting.

Citation Format: Yong Hwa Jo, Minh Nam Nguyen, Tae Gyu Choi, Sung Soo Kim. LSD1 stimulates cell survival and epigenetic homeostasis via snail in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5471. doi:10.1158/1538-7445.AM2017-5471
Abstract 5473: Towards a better understanding of MTH1 as a therapeutic target in RAS-driven cancer
Authors: Samaranayake Govindi J. , Troccoli Clara I. , Huynh Mai Q. , Win Andrew , Ji Debin , Kool Eric T. , Rai Priyamvada
Published: July 2017

Oncogenic RAS signaling-generated reactive oxygen species (ROS) drive tumor progression by the hyperactivation of proliferative, anti-apoptotic, and metastatic pathways. Elevated ROS levels however can also cause oxidative DNA damage, leading to oncogene-induced senescence (OIS) and cell death. To avoid such tumor-suppressive outcomes, RAS-driven tumors often upregulate redox-protective proteins. The collective research from our group over the last few years has shown that oncogenic RAS elevates expression of the mammalian 8-oxo-dGTPase MutT Homolog 1 (MTH1), which in turn enables evasion of OIS, promotes transformation efficiency, and facilitates tumorigenicity. Our prior work has therefore demonstrated that MTH1 is beneficial to the spectrum of RAS-driven transformation, and that its shRNA-mediated targeting in oncogenic RAS-harboring lung cancer cells produces robust tumor-suppressive outcomes. However the first wave of chemical MTH1 inhibitors has led to controversial and conflicting results regarding MTH1 as a chemotherapeutic target. Here we evaluate the benefit of MTH1 inhibitors in wildtype. vs. oncogenic KRAS expressing cells, and directly assess the effects of oncogenic KRAS as well as three recently developed inhibitors on MTH1 8-oxo-dGTPase activity. Our results support that introduction of oncogenic KRAS elevates both MTH1 expression and activity, presumably through its elevation of ROS levels, and thus sensitizes cells to MTH1 inhibitors. The degree of this sensitization has a complex dependence on residual 8-oxodGTPase activity in the different cells following treatment with the MTH1 inhibitors, alternate antioxidant responses, and induction of different tumor suppressor pathways. Our data therefore highlight the importance of evaluating the molecular contexts and outcomes of MTH1 inhibition when determining its utility as a chemotherapeutic target.

Citation Format: Govindi J. Samaranayake, Clara I. Troccoli, Mai Q. Huynh, Andrew Win, Debin Ji, Eric T. Kool, Priyamvada Rai. Towards a better understanding of MTH1 as a therapeutic target in RAS-driven cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5473. doi:10.1158/1538-7445.AM2017-5473
Abstract 5479: Redox stress as a therapeutic Achilles heel in castration-resistant prostate cancer
Authors: Troccoli Clara I. , Samaranayake Govindi J. , Huynh Mai Q. , Kage Karen , Kwon Deukwoo , Ban Yuguang , Chen Xi S. , Zarco Enrique R. , Jorda Merce , Burnstein Kerry L. , Rai Priyamvada
Published: July 2017

Androgen deprivation therapy (ADT) initially suppresses prostate cancer (PC) progression. However, castration resistant PC (CRPC) cells inevitably emerge, resulting in incurable disease. We recently demonstrated that AD produces a form of cellular senescence leading to outgrowth of CRPC subpopulations from the AD-sensitive parental cells. Gene expression profiling studies comparing the parental LNCaP line to the senescence-resistant, early CRPC variant, LNCaP SB5, revealed an enrichment of thiol-based redox-protective proteins in the latter under AD conditions. This finding suggests that redox stress due to hyperactivated mitogenic/survival signaling or metabolic stresses may be an important and understudied Achilles heel in the progression to CRPC. Here we present the effects of inhibiting thioredoxin-1 (TRX1), a redox-protective protein that was identified as being elevated in our early CRPC LNCaP SB5 model. Suppression of TRX1 expression via shRNA led to profound growth suppression of CRPC cells, relative to their AD-sensitive counterparts, and significantly reduced CRPC xenograft tumor growth. Furthermore, under AD, TRX1 suppression promoted p53-induced cell death, which was accompanied by increased reactive oxygen species (ROS). These in vitro and in vivo results were recapitulated using a Phase II clinical trial-tested chemical TRX1 inhibitor. Thus our results point to TRX1 as a critical requirement for CRPC progression and provide a rationale for using TRX1 inhibitors in conjunction with ADT to limit CRPC.

Citation Format: Clara I. Troccoli, Govindi J. Samaranayake, Mai Q. Huynh, Karen Kage, Deukwoo Kwon, Yuguang Ban, Xi S. Chen, Enrique R. Zarco, Merce Jorda, Kerry L. Burnstein, Priyamvada Rai. Redox stress as a therapeutic Achilles heel in castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5479. doi:10.1158/1538-7445.AM2017-5479
Abstract 5480: Peroxiredoxin 2 mediates the survival of ECM-detached ovarian cancer cells
Authors: Davison-Versagli Calli A.
Published: July 2017

Non-tumorigenic epithelial cells require anchorage to the extracellular matrix (ECM) in order to survive; however, it has been recognized that metastatic cancer cells must have the ability to survive in anchorage independence. Approximately 70% of epithelial ovarian cancer (EOC) cases are diagnosed after EOC cells have already metastasized, making EOC more difficult to treat. EOC cells shed from the primary tumor and accumulate in ascites in the peritoneal cavity before attaching and forming secondary tumors throughout the peritoneal cavity. A better understanding of the molecular mechanisms involved in the survival of this non-adhesive subset of cells that survive in anchorage independence in the ascites could lead to the development of improved chemotherapeutics and thus resulting in better survival rates of EOC patients. Striking increases of reactive oxygen species (ROS) mediated by ECM-detachment has been shown to inhibit survival in non-tumorigenic mammary epithelial cells. Furthermore, previous publications from our laboratory suggest that the antioxidant enzymes catalase, superoxide dismutase 1 (SOD1), and superoxide dismutase 2 (SOD2) are critical for metabolic maintenance and survival of ECM-detached breast cancer cells; however, many other antioxidant enzymes and their role in the survival of ECM-detached ovarian cancer cells have yet to be unveiled. Here, we have found that the antioxidant enzyme, Peroxiredoxin 2, is important in the survival of ECM-detached ovarian cancer cells, and elimination of this enzyme in SKOV3 cells results in decreased ability to survive in anchorage independence. Thus, our data reveal that Peroxiredoxin 2 may be an attractive target for the design of chemotherapeutics aimed at eliminating metastatic ovarian cancer cells. Given these data, we are working to understand the role of other members of the Peroxiredoxin family, namely Peroxiredoxin 1, in the survival of ovarian cancer cells in anchorage independence.

Citation Format: Calli A. Davison-Versagli. Peroxiredoxin 2 mediates the survival of ECM-detached ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5480. doi:10.1158/1538-7445.AM2017-5480
Abstract 5483: Investigating the role of the retinoblastoma protein in induction and maintenance of oncogene-induced cellular senescence in tumor suppression
Authors: Harajly Mohamad , Zalzali Hasan , Ghamloush Farah , Saab Raya H.
Published: July 2017

Oncogene-induced cellular senescence is a tumor suppressor response resulting in irreversible cell cycle exit, and is dependent on the p53 and RB pathways. Loss of p53 has recently been shown to allow re-entry of senescent cells into the cell cycle. The role of the RB1 protein in maintenance of the senescent state is less well studied. We investigated whether RB1 is necessary for the induction as well as the maintenance of oncogene-induced senescence, and we also evaluated whether RB1 activation is sufficient to induce and/or maintain senesce in the absence of a functional p53 pathway. Inactivation of RB1 prior to onset of senescence led to failure of senescence induction, with impaired cell cycle exit and failure to induce senescence markers. On the other hand, loss of RB1 after cells had already entered oncogene-induced senescence was able to reverse some features of the senescence phenotype, but did not result in successful cell division and accumulation. Interestingly, in the absence of p53, constitutively active RB1 was sufficient for cells to undergo oncogene-induced senescence, and effectively prevented colony formation. Finally, while p53 inactivation was sufficient for senescent cells to re-enter the cell cycle, constitutive activation of RB1 prevented cell cycle re-entry, even in the absence of p53. Our findings show that RB1 is necessary for both the induction and maintenance of oncogene-induced senescence, and that active RB is sufficient for senescence induction as well as its maintenance, both in the presence and absence of p53. These results have direct implications on targeting RB activation as a senescence-inducing approach in both p53 wild type and p53-defective premalignant and malignant tumors.

Note: This abstract was not presented at the meeting.

Citation Format: Mohamad Harajly, Hasan Zalzali, Farah Ghamloush, Raya H. Saab. Investigating the role of the retinoblastoma protein in induction and maintenance of oncogene-induced cellular senescence in tumor suppression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5483. doi:10.1158/1538-7445.AM2017-5483
Abstract 5485: The combined effects of polyamine and GSH inhibition on the viability of human cancer cell lines
Authors: Grady John , Holzer Davey , Keleher Kaci , Meetz Emma , Feirer Russ
Published: July 2017

Polyamines play essential roles in DNA stability and cell proliferation, making polyamine metabolism a potential target for cancer therapeutics. The spermine analog N1,N11- Diethylnorspermine (DenSpm) reduces levels of ODC, the enzyme responsible for polyamine biosynthesis, and also induces the enzyme SSAT, responsible for the catabolism of polyamines. Polyamines have been shown to inactivate reactive oxygen species (ROS), including peroxides, protecting mammalian cells from oxidative damage to nucleic acids. The catabolism of polyamines by SSAT, in contrast, leads to the production of ROS, which results in cellular death and limits the progression of cancer. Buthionine sulfoximine (BSO) selectively depletes stores of intracellular glutathione GSH, an antioxidant that neutralizes ROS. We hypothesized that treating cancer cell lines with both DenSpm and BSO will have a synergistic cytotoxic effect on the cells, due to the depletion of ROS-scavenging polyamines, the generation of ROS caused by DenSpm and the absence of GSH. Treatment of the four cell lines, MCF-7, MDA-MD-231, Caco-2 and PANC-1, with DenSpm resulted in moderate reductions in cell viability as measured using the Cell Titer Blue assay (Promega, Inc.). As has been widely reported in other mammalian systems, DenSpm (10 µM) reduced intracellular polyamine concentrations (HPLC of benzoylated polyamine derivatives) and induced SSAT (Western Blots). Treatment of cells with BSO (500 µM) caused a significant decrease in intracellular GSH levels. Similar findings have been reported in previous studies with human neuroblastoma lines (Anderson, et al. 1999). The combination of BSO and DenSpm had effects markedly greater than either compound alone. Pretreatment of cells with BSO (500 µM) for 24 hours with subsequent removal of BSO before DenSpm (10, 100, 1000 µM) addition resulted in significantly reduced viability in all cell lines. DenSpm was found to be most effective in the continued presence of BSO as compared to a 24-hour BSO pretreatment. The compounds used in combination also enhanced ROS production, further demonstrating their synergistic effects.

Citation Format: John Grady, Davey Holzer, Kaci Keleher, Emma Meetz, Russ Feirer. The combined effects of polyamine and GSH inhibition on the viability of human cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5485. doi:10.1158/1538-7445.AM2017-5485
Abstract 5486: Oxidative stress and selective protein carbonylation in human breast cancer tissue
Authors: Aryal Baikuntha P. , Rao Ashutosh
Published: July 2017

Protein carbonylation is an irreversible modification to the side chain of amino acid residues induced by severe oxidative stress. Reactive oxygen species (ROS) are constantly produced under normal as well as stress-induced conditions, and play a role in both cancer progression and cancer suppression. Tumor tissue are known to have higher ROS levels compared to surrounding healthy tissue but ROS-induced specific protein carbonylation and its unique role in cancer progression/suppression are poorly understood. In this study we compared the relative total and specific protein carbonylation in flash frozen human breast cancer and matched adjacent normal tissue using ELISA, two-color western blot, mass spectrometry, and immunoprecipitation approaches. To understand antioxidant capacity in tumor tissue, we analyzed superoxide dismutase (SOD) for its antioxidant activity and protein level. Our results indicate that tumor tissue has greater total protein carbonylation, lower SOD activity, lower SOD protein levels, and elevated levels of autophagy compared to matched adjacent healthy tissue. We also identified three specific proteins that showed higher level of carbonylation selectively in tumor tissue compared to adjacent normal tissue. Our findings were further confirmed using the immortalized MDA-MB-231 breast cancer cell line and MCF-12A noncancerous normal human epithelial breast cell. Identification of selectively carbonylated proteins in cancer tissue, and understanding their specific role in cancer progression may promote the development of targeted therapeutic approaches to mitigate or enhance oxidative damage of such proteins selectively in tumor tissue.

Citation Format: Baikuntha P. Aryal, Ashutosh Rao. Oxidative stress and selective protein carbonylation in human breast cancer tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5486. doi:10.1158/1538-7445.AM2017-5486
Abstract 5490: Non-overlapping promoter and super-enhancer-associated dependencies in multiple myeloma
Authors: Fulciniti Mariateresa , Lin Charles Y. , Samur Mehmet K. , Young Richard , Avet-loiseau Herve , Anderson Kenneth , Bradner James , Munshi Nikhil
Published: July 2017

The relationship between promoter proximal transcription factor-associated gene expression and super-enhancer-driven transcriptional programs are not well-defined. We explored the transcriptional and functional interrelationship between E2F transcription factors and BET transcriptional co-activators to identify their individual contribution to eventual functional effect in multiple myeloma (MM). To better understand how E2F1 and DP1 drive proliferation, we mapped the global occupancy of E2F1/DP1 in MM. Integration of E2F1 and DP1 genomic localization to MM reference epigenome revealed specific co-occupancy of the factors at promoters of active genes marked by H3K4me3, with a strong positive correlation between E2F and RNA Polymerase II (RNA Pol II) binding at transcription start sites. In contrast, active enhancers, as defined by promoter distal Mediator (MED1) peaks and marked by H3K27ac and BRD4, showed virtually no E2F binding. Unbiased hierarchical clustering revealed distinct regulatory axes for E2F and BETs, with E2F predominantly localized to active gene promoters of growth/proliferation genes and BETs disproportionately at enhancer- regulated tissue specific genes confirming that these factors establish distinct target gene programs. At the extremes, we found less than 10% of genes were among the top 500 in BRD4 enhancer signal (i.e. SE-regulated) and top 500 E2F promoter signal. We hypothesized that the presence of BETs and E2F in distinct regulatory axes divides active genes in MM into those that can be selectively influenced by BET inhibition or E2F perturbation, but not both. In line with this we have observed that dual E2F and BET inhibition is synergistic for MM cell growth, both in vitro and in vivo. In conclusions, our results highlights the existence of distinct regulatory axes controlled by promoter and enhancer driven processes, suggesting a sequestered cellular functional control that may be perturbed in cancer with potential for development of a promising therapeutic strategy.

Citation Format: Mariateresa Fulciniti, Charles Y. Lin, Mehmet K. Samur, Richard Young, Herve Avet-loiseau, Kenneth Anderson, James Bradner, Nikhil Munshi. Non-overlapping promoter and super-enhancer-associated dependencies in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5490. doi:10.1158/1538-7445.AM2017-5490
Abstract 5493: The cistrome of estrogen receptor beta in colorectal cancer cells
Authors: Indukuri Rajitha , Wang Jun , Mesmar Fahmi , Williams Cecilia
Published: July 2017

Colorectal cancer (CRC) is the second leading cause of death in the United States and a truly preventive approach still remains to be developed. Men have the highest incidence rate for CRC and pre-menopausal women have a lower incidence of CRC, suggesting hormonal factors mediate protective roles. ERβ is the predominantly expressed estrogen receptor in the colonic epithelium and is lost during CRC progression. In colon cancer cell lines re-expression of ERβ has anti proliferative and anti-inflammatory properties, there is however little understanding of the mechanism whereby ERβ mediates these effects in colon cells. In order to elucidate the mechanism of ERβ in CRC, we re-expressed this receptor using lentivirus in four different CRC cell lines. We optimize chromatin-immunoprecipitation (ChIP) with an antibody thoroughly validated for this purpose and used IgG and input as well as cell lines without ERβ expression as controls. ChIP-seq was performed using Illumina library preparation and next generation sequencing. Alignment of sequence reads against the reference genome of version hg19 was done using Bowtie, and statistically significant peaks (FDR) were identified using MACS. Results were compared to RNA-seq analysis of the same cell lines. Key binding-sites and corresponding gene regulations were confirmed using qPCR. We present for the first time, the cistrome of ERβ in different CRC cell lines. We identify key binding motifs, including ERE and AP-1 sites. Together, our results uncover ERβ as an important determinant for attenuating cancer progression.

Note: This abstract was not presented at the meeting.

Citation Format: Rajitha Indukuri, Jun Wang, Fahmi Mesmar, Cecilia Williams. The cistrome of estrogen receptor beta in colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5493. doi:10.1158/1538-7445.AM2017-5493