bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 580: Epigenetic silencing of ARRDC3 expression in basal-like breast cancer cells
Authors: Song Young Hwa , Chung Jun
Published: May 2015

Arrestin domain-containing 3 (ARRDC3) is a tumor suppressor whose expression is either lost or suppressed in basal-like breast cancer (BLBC). However, the mechanism by which BLBC suppresses ARRDC3 expression is not established. Here, we show that expression of ARRDC3 in BLBC cells is suppressed at the transcriptional level. Suppression of ARRDC3 expression in BLBC cells involves epigenetic silencing as inhibitors of class III histone deacetylases (HDACs) significantly restores ARRDC3 levels in BLBC cells. SIRT2, among class III HDACs, plays a major role in epigenetic silencing of ARRDC3 in MDA-MB-231 cells. Acetylation levels of the ARRDC3 promoter in BLBC cells is significantly lower than that of other sub-types of BC cells. Chromatin immunopreciptitation analysis established SIRT2 binding at ARRDC3 promoter in BLBC cells. Our studies indicate that SIRT2 dependent epigenetic silencing of ARRDC3 is one of the important events that may contribute to the aggressive nature of BLBC cells.

Citation Format: Young Hwa Song, Jun Chung. Epigenetic silencing of ARRDC3 expression in basal-like breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 580. doi:10.1158/1538-7445.AM2014-580
Abstract 619: Selective estrogen mimics for the treatment of tamoxifen-resistant breast cancer
Authors: Molloy Mary Ellen , White Bethany Perez , Zhao Huiping , Michalsen Bradley T. , Patel Hitisha K. , Zhao Jiong , Xiong Rui , Siklos Marton I. , Thatcher Gregory R.J. , Tonetti Debra A.
Published: May 2015

Endocrine-resistant breast cancer, whether de novo or acquired, is a major clinical obstacle. Although recent clinical trials have demonstrated the efficacy of 17β-estradiol (E2) or diethylstilbestrol (DES) following exhaustive use of antiestrogens, E2 treatment is associated with major side effects such as an increased risk of other gynecological cancers, deterring the clinical community from adopting it as a treatment strategy. Our lab has previously shown that Protein kinase C alpha (PKCα) overexpression predicts tamoxifen (TAM) resistance in the clinic (Tonetti DA et al., Br J Cancer. 2003) and may also predict a positive response to an estrogenic therapy (Chisamore MJ et al., Clinical Cancer Research. 2001). Further, the ectopic overexpression of PKCα in T47D breast cancer cells, led to a TAM-resistant, E2-inhibited phenotype in vivo which was accompanied by the translocation of estrogen receptor alpha (ERα) to extranuclear sites (Perez White B et al., Molecular Cancer. 2013). The purpose of this study was to identify novel selective estrogen mimics (SEMs), which could achieve the positive therapeutic effects of E2 treatment in TAM-resistant breast cancers, while minimizing the side effects. In vitro screening identified two SEMs, BTC and TTC-352, which displayed estrogenic activity in breast cancer cell lines. BTC and TTC-352 treatment resulted in significant tumor regression in two xenograft models of TAM-resistant, PKCα-overexpressing breast cancer. Similar to E2, T47D:A18/PKCα tumor regression was accompanied by translocation of ERα to extranuclear sites, possibly defining a mechanism through which these SEMs initiate tumor regression. SEM treatment, however, did not result in growth of parental, TAM-sensitive xenograft tumors. Endometrial thickening, caused by both E2 and TAM, is directly associated with gynecological carcinogenesis and uterine cancer. Interestingly, SEM treatment did not increase uterine weight in mice suggesting negligible hormonal stimulation in gynecological tissues. Both BTC and TTC-352 resulted in regression of two TAM-resistant breast cancer models, while displaying enhanced safety compared to E2 and TAM. These data suggest that further development of SEMs targeted to TAM-resistant breast cancer is a feasible therapeutic strategy.

Citation Format: Mary Ellen Molloy, Bethany Perez White, Huiping Zhao, Bradley T. Michalsen, Hitisha K. Patel, Jiong Zhao, Rui Xiong, Marton I. Siklos, Gregory R.J. Thatcher, Debra A. Tonetti. Selective estrogen mimics for the treatment of tamoxifen-resistant breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 619. doi:10.1158/1538-7445.AM2014-619
Abstract 625: Proliferative effects of the phytoestrogens 8-Prenylnaringenin, 6-(1.1-dimethylallyl)naringenin and Naringenin in MCF-7 cells and the rat mammary gland
Authors: Helle Janina , Zierau Oliver , Kräker Kristin , Keiler Annekathrin , Vollmer Günter , Welsh JoEllen , Kretzschmar Georg
Published: May 2015

Evaluation of stimulation of proliferation in female reproductive organs by phytoestrogens of reproductive tract organs is important to estimate their safety/risk profile if used as an alternative to hormone therapy. To assess the proliferative capacity of the flavanones 8-Prenylnaringenin (8-PN), 6-(1.1-dimethylallyl)naringenin (6-DMAN) and Naringenin (Nar) on the mammary gland we compared their estrogenic properties to 17β-Estradiol (E2) in three independent assays. We performed competitive estrogen receptor (ER) ligand binding assays, MCF-7 proliferation studies and a three day exposure experiment in young adult ovariectomized female rats. 8-PN displayed a high relative binding affinity for both ERs with a preference for ERα (19.46 %) compared to ERβ (6.5 %). Among the tested flavanones 8-PN had the strongest mitotic effect on MCF-7 cells. In vivo 8-PN increased the number of terminal end buds (TEB) in the mammary gland and the protein expression of the proliferation markers Ki-67 and PCNA in epithelial ductal cells and further led to an increase of Amphiregulin (Areg) mRNA expression, endpoints correlated to mammary gland proliferation. 6-DMAN also possesses a higher relative binding affinity for the ERα than for the ERβ (1.46 %, 0.84 %) and stimulated the cell proliferation of MCF-7 cells. It enhanced Ki-67 protein expression and β-Casein mRNA expression in vivo. Nar displayed the weakest estrogenic properties and was the only tested compound with a higher affinity for the ERβ than the ERα (0.5 %, 0.08 %). It displayed proliferative effects on MCF-7 cells and slightly induced Ki-67 protein expression in vivo.

Citation Format: Janina Helle, Oliver Zierau, Kristin Kräker, Annekathrin Keiler, Günter Vollmer, JoEllen Welsh, Georg Kretzschmar. Proliferative effects of the phytoestrogens 8-Prenylnaringenin, 6-(1.1-dimethylallyl)naringenin and Naringenin in MCF-7 cells and the rat mammary gland. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 625. doi:10.1158/1538-7445.AM2014-625
Abstract 645: IGM-55.5, a novel monoclonal human recombinant IgM antibody with potent activity against B cell leukemia and lymphoma
Authors: Duramad Omar , Wang Beatrice , Zheng Fen , Keyt Lena , Repellin Claire , Beviglia Lucia , Bhat Neelima , Bieber Marcia , Teng Nelson , Keyt Bruce
Published: May 2015

IGM-55.5 is an engineered monoclonal human recombinant IgM antibody that was derived from a natural monoclonal antibody 216 isolated at Stanford University from the splenocytes of a patient with Non-Hodgkin's lymphoma. HuMab 216 was previously used in a B-cell acute lymphoblastic leukemia phase I trial and was demonstrated to be well tolerated with significant decrease in peripheral blasts observed (Liedtke et al, Haematologica, 2012). IGM-55.5 has been engineered to be mono-reactive and recognizes a carbohydrate determinant as an epitope on normal human B cells as well as B-cell lymphoma and B-progenitor lymphoblasts.

Here, we report new preclinical studies that describe the mechanism of action and potent activity of IGM-55.5. In-vitro analysis of IGM-55.5 was found to have high surface binding on a broad panel of B cell leukemia and lymphoma cells lines by flow cytometry. IGM-55.5 binding leads to the disruption of the plasma membrane and formation of large membrane pores resulting in cell lysis. This non-classical apoptosis occurs in the absence of complement fixation but in vitro cytotoxicity is increased in assays in the presence of human complement. Studies with aggressive disseminated tumor xenograft models (Namalwa, Granta, & Nalm-6) demonstrate that IGM-55.5 significantly prolongs survival and reduces circulating tumor cells. Peripheral blood samples from chronic lymphocytic leukemia patients demonstrated the potent activity of IGM-55 in eliminating B cell lymphoblasts in comparison with Rituxan when treated in-vitro. These data taken together highlight the potent activity of IGM-55.5 as therapeutic for advanced B cell malignancies, especially indicated for Rituxan resistant or refractory patients.

Citation Format: Omar Duramad, Beatrice Wang, Fen Zheng, Lena Keyt, Claire Repellin, Lucia Beviglia, Neelima Bhat, Marcia Bieber, Nelson Teng, Bruce Keyt. IGM-55.5, a novel monoclonal human recombinant IgM antibody with potent activity against B cell leukemia and lymphoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 645. doi:10.1158/1538-7445.AM2014-645
Abstract 655: Effect of antibody mixtures on HER-family heterodimerization
Authors: Ellebæk Sofie , Bouquin Thomas , Grandal Michael V. , Kragh Michael , Poulsen Thomas T.
Published: May 2015

Members of the human epidermal growth factor receptor (HER)-family, i.e. EGFR, HER2, and HER3, are key oncogenic drivers in numerous cancer forms. Monoclonal antibody therapeutics targeting EGFR and HER2 have been clinically approved and HER3-targeting antibodies are in clinical development. However, resistance to single HER treatment occurs due to mechanisms such as incomplete target elimination and a switch of receptor dependency in the resistant cancer cell population. Another potential escape mechanism for the cancer cells to become resistant and maintain oncogenic signaling is receptor heterodimerization. It is therefore relevant to investigate how heterodimers can be downregulated when targeted with antibodies against a single or multiple HER targets. It is well established that mixtures of two or more antibodies against a single HER family receptor induce superior and rapid receptor downregulation and elimination compared with monoclonal antibodies. However, the effect of antibody mixtures on HER heterodimer distribution has not been investigated.

At Symphogen, we have generated Pan-HER, a combination of two EGFR-, two HER2-, and two HER3-targeting monoclonal antibodies with non-overlapping epitopes in a single drug compound. Detection and quantification of the HER family member distribution in selected cancer cell lines, as well as proliferation assays with combinations of the antibody components comprising Pan-HER have been performed to investigate the effects of 2-, 4- and 6-mixtures of antibodies. Results from studies focusing on characterization of receptor levels, surface expression and heterodimer formation in Pan-HER responsive cancer cell lines will be presented, as well as the effect of Pan-HER on receptor heterodimer distribution, investigated by Co-IP and Duolink Proximity Ligation Assay technology. Our results show that mixtures of antibodies against more than one HER family member potently downregulate the HER family receptor levels and significantly alter the HER family heterodimerization pattern upon short- and long-term exposure to HER-targeting antibodies.

Citation Format: Sofie Ellebæk, Thomas Bouquin, Michael V. Grandal, Michael Kragh, Thomas T. Poulsen. Effect of antibody mixtures on HER-family heterodimerization. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 655. doi:10.1158/1538-7445.AM2014-655
Abstract 656: A bispecific HER2/CD3 targeting FynomAb with excellent tumor killing and favorable pharmacokinetic properties
Authors: Wuellner Ulrich , Buller Fabian , Klupsch Kristina , Brack Simon , Zbinden Irene , Santimaria Roger , Attinger-Toller Isabella , König-Friedrich Susann , Bertschinger Julian , Grabulovski Dragan
Published: May 2015

There is increasing evidence that T cells are able to control tumor growth and increase survival of cancer patients. However, tumor-specific T cell responses are difficult to mount and sustain in cancer patients, and are limited by numerous immune escape mechanisms of tumor cells. A promising approach in the immunotherapy of cancer is to engage T cells to target tumor cells using bispecific therapeutics targeting a tumor-associated surface antigen and CD3e on T cells. Such therapeutics elicit T cell mediated lysis of tumor cells independent of T cell specificity.

Fynomers are small 7 kDa globular proteins derived from the SH3 domain of the human Fyn kinase (Fyn SH3) that can be engineered to bind with antibody-like affinity and specificity to virtually any target of choice. Fynomers can be fused to N-terminal and/or C-terminal ends of antibodies to generate multispecific therapeutics (FynomAbs) with tailored architectures. FynomAbs can be produced using standard antibody technology (GMP production yield of 3.3 g/L at 1000 L scale achieved), and show IgG-like biophysical properties and pharmacokinetic profiles.

We have generated a novel bispecific FynomAb which can simultaneously bind HER2 on tumor cells and CD3 on T cells. The bispecific HER2/CD3 targeting FynomAb COVA420 potently redirected T cells to HER2 expressing tumor cells showing picomolar tumor cell lysis activity. We present for the first time that a tailored architecture of the FynomAb leads to optimal tumor cell killing properties. The activity of COVA420 was found to be highly specific, as no lysis of cells was observed in the absence of HER2 expression.

In addition, COVA420 demonstrated an antibody-like pharmacokinetic profile in mice. We anticipate that the increased half-life of T cell recruiting FynomAbs compared to other bispecific formats translates into a significant benefit for patients, since it circumvents the need for continuous infusion and prolongs the intervals between successive treatments.

In summary, bispecific T cell recruiting FynomAbs represent a novel platform technology to redirect T cells to tumor cells with optimal biophysical properties, long-half lives and tailored architectures.

Citation Format: Ulrich Wuellner, Fabian Buller, Kristina Klupsch, Simon Brack, Irene Zbinden, Roger Santimaria, Isabella Attinger-Toller, Susann König-Friedrich, Julian Bertschinger, Dragan Grabulovski. A bispecific HER2/CD3 targeting FynomAb with excellent tumor killing and favorable pharmacokinetic properties. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 656. doi:10.1158/1538-7445.AM2014-656
Abstract 664: Amanitin-based antibody-drug conjugates targeting the prostate-specific membrane antigen
Authors: Hechler Torsten , Kulke Michael , Mueller Christoph , Pahl Andreas , Anderl Jan
Published: May 2015

Antitumoral activity of monoclonal antibodies can be dramatically enhanced by conjugation to toxic small molecules. Beside the recent approval of Kadcyla (T-DM1) and Adcetris (SGN-35) more than 30 antibody-drug conjugates (ADC) have entered clinical trials, promising to strengthen the therapeutic capabilities for cancer treatment in the next decade. Surprisingly most ADCs are based on one of few toxic compounds only and on an even smaller number of toxicity mechanisms: Most antibodies are coupled to the microtubuli-targeting auristatins and maytansines. Toxins that operate through such a mechanism could suffer from limited activity in different cancer indications and in cells expressing resistance mechanisms. Accordingly the use of new drugs that function via alternative toxicity mechanisms could enhance the therapeutic potential of ADCs.

In the present study we evaluated the antitumoral potency of a monoclonal antibody targeting the prostate-specific membrane antigen (PSMA) conjugated to small molecules from the amatoxin family. PSMA is a membrane antigen overexpressed in prostate cancer and an attractive target for an ADC approach, as it shows low expression by most normal tissues and sufficient internalization after antibody binding. Amanitin, the most well-known toxin of the amatoxin family, binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription at very low concentrations. In our experiments, we tested several random- and site-specific strategies to covalently conjugate amanitin to the antibody and generated conjugates with low aggregation and high affinity for the target antigen. Using a series of PSMA-expressing cells we compared the cytotoxic activity of stable and cleavable linker ADCs and the stability of such constructs in plasma. Overall we observed picomolar activity of ADCs after incubation for three to five days with PSMA-positive prostate cancer cells independent of the hormone-sensitivity status. Moreover we demonstrated high activity of amanitin-based anti-PSMA ADCs in prostate cancer xenograft models. The data encourage the evaluation of these agents in a clinical advanced prostate cancer study.

Note: This abstract was not presented at the meeting.

Citation Format: Torsten Hechler, Michael Kulke, Christoph Mueller, Andreas Pahl, Jan Anderl. Amanitin-based antibody-drug conjugates targeting the prostate-specific membrane antigen. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 664. doi:10.1158/1538-7445.AM2014-664
Abstract 682: Identification of HSP90 inhibitor sensitizers through pooled RNA interference screen
Authors: Chen Yaoyu , Chen Jinyun , Loo Alice , Mclaughlin Margaret , Pagliarini Raymond , Zhou Wenlai
Published: May 2015

Key words: HSF1, cancer cells, HSP90 inhibitor, Melanoma, HCC, DEDD2.

The molecular chaperone heat shock protein 90 (HSP90) facilitates the appropriate folding of various oncogenic proteins and is necessary for the survival of some cancer cells. HSP90 is therefore an attractive drug target, but the efficacy of HSP90 inhibitor may be limited by HSP90 inhibition induced feedback mechanisms. To identify genes that modulate the efficacy of HSP90 inhibition on tumor cell growth, we performed a large-scale RNA interference (RNAi) genetic screen with a collection of short hairpin RNA (shRNA) vectors targeting 1,000 human genes in A375. A barcoding technique was used to identify genes whose suppression caused resistance or sensitivity to two separate concentrations of NVP-AUY922. 163 and 360 shRNA constructs were significantly depleted form either low- or high-dose NVP-AUY922 treated samples (FDR<=0.15). Among those shRNA hits, 84 hits (including 81 genes) were common shRNA hits as shown in Venn diagram and sensitizing genes or rescuing genes were also shown. Among of these shRNA hits, HSF1 and heat shock protein 90 alpha, class B member 1(HSP90AB1) knockdown scored as the most top sensitizers to HSP90 inhibition in A375 cells, and are known to regulate the cell response to heat shock conditions, which may reflect the potential feedback mechanism of HSP90 inhibition. Taking together, HSF1 is identified as a sensitizer of HSP90 inhibitor through pooled shRNA screening. A striking combinational effect was observed when HSF1 knockdown plus with HSP90 inhibitors treatment in various cancer cell lines: A375, A2058 and HCT116 and tumor mouse models. Interestingly, HSF1 is highly expressed in hepatocellular carcinoma (HCC) patient samples and HCC is sensitive to combinational treatment, indicating a potential indication for the combinational treatment. To understand the mechanism of the combinational effect, we identified that a HSF1-target gene DEDD2 is involved in attenuating the effect of HSP90 inhibitors. Thus, the transcriptional activities of HSF1 induced by HSP90 inhibitors provide a feedback mechanism of limiting the HSP90 inhibitor's activity, and targeting HSF1 may provide a new avenue to enhance HSP90 inhibitors activity in human cancers.

Citation Format: Yaoyu Chen, Jinyun Chen, Alice Loo, Margaret Mclaughlin, Raymond Pagliarini, Wenlai Zhou. Identification of HSP90 inhibitor sensitizers through pooled RNA interference screen. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 682. doi:10.1158/1538-7445.AM2014-682
Abstract 73: Ewing's sarcoma Ewsa protein regulates Sox9 during skeletogenesis in zebrafish
Authors: Merkes Chris , Turkalo Timothy K. , Wilder Nicole , Park Hyewon , Azuma Mizuki
Published: May 2015

Ewing's sarcoma is the second most common bone cancer in adolescents and is characterized by the aberrant chimeric fusion gene EWS/FLI1. Wild-type EWS has been proposed to play a role in splicing and transcription, but how these functions affect early development is unknown. To elucidate the function of EWS in early development, we analyzed a mutant ewsa zebrafish line. We generated a maternal zygotic (MZ) ewsa/ewsa line because the ewsa/wt and ewsa/ewsa zebrafish appear to be normal and fertile. The adult MZ ewsa/ewsa mutants display defects in the craniofacial bones (dentary and basihyal). Compared to wt/wt, the MZ ewsa/ewsa mutants have a higher number of craniofacial prehypertrophic chondrocytes, and they fail to mature into hypertrophic chondrocytes possibly due to impaired intercalation at 4 days post-fertilization (dpf). The adult MZ ewsa/ewsa mutants also display curved spines due aberrant differentiation of the nucleus pulposus cells in the intervertebral discs (IVD). These altered differentiation is preceded by increased Collagen type II in the IVD, and Ctgf in the craniofacial chondrocytes in MZ ewsa/ewsa mutants compared to wt/wt at 36 hpf. We further discovered that both Ewsa and Ewsb interact with the master transcriptional factor for chondrogenesis, Sox9, in zebrafish. Consistently, qPCR analysis consistently demonstrated that Sox9 target genes are either upregulated (ctgfa, ctgfb, col2a1a, col2a1b) or downregulated (sox5, nog1, nog2, bmp4) in MZ ewsa/ewsa mutants compared to the wt/wt zebrafish embryos. This study is the first demonstration of Ewsa-dependent regulation of skeletogenesis through modulation of Sox9 target gene expression.

Citation Format: Chris Merkes, Timothy K. Turkalo, Nicole Wilder, Hyewon Park, Mizuki Azuma. Ewing's sarcoma Ewsa protein regulates Sox9 during skeletogenesis in zebrafish. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 73. doi:10.1158/1538-7445.AM2014-73
Abstract 760: Suppression of ABCG2 mediated MDR in vitro and in vivo by a novel inhibitor of ABCG2 transport
Authors: Patel Atish S.
Published: May 2015

Cancer is a disease whose treatment is often limited due to the development of a phenomenon known as multidrug resistance (MDR) that is its Achilles’ heel. Hence there is an immense demand for development of novel agents that can overcome the emergence of multidrug resistance (MDR) in cancer. A group of transmembrane proteins called ABC (ATP- binding cassette) transporters, present ubiquitously in the human body possesses a modular architecture, contributing immensely towards the development of MDR in various tumor types.

An analysis of structural congeners among a group of compounds led to the discovery of CCTA-1523 that could selectively reverse ABCG2-mediated MDR in cancer cells both in vitro and in vivo. CCTA-1523 at concentrations upto 5 μM sensitized the cancer cells as well as transfected cells overexpressing ABCG2 to the substrate chemotherapeutic drugs. The reversal ability of CCTA-1523 was primarily due to the inhibition of the active efflux function of the transporter; also there was no change in the protein expression of the ABCG2 transporter in the presence of CCTA-1523 at reversing concentrations. Importantly the reversal effect produced by CCTA-1523 was reversible. Co-administration of CCTA-1523 restored the in vivo antitumor activity of doxorubicin in ABCG2 overexpressing tumor xenografts without added toxicity. Taken together, our findings indicate that CCTA-1523 is a potent and reversible, modulator of ABCG2 export function that may offer therapeutic promise for multidrug- resistant malignancies.

Citation Format: Atish S. Patel. Suppression of ABCG2 mediated MDR in vitro and in vivo by a novel inhibitor of ABCG2 transport. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 760. doi:10.1158/1538-7445.AM2014-760
Abstract 781: Efficacy of trifluridine for 5-fluorouracil-resistant human gastric cancer cell lines and their mechanisms
Authors: Matsuoka Kazuaki , Kobunai Takashi , Takechi Teiji
Published: May 2015

Background: TAS-102 is a novel oral nucleoside antitumor agent consisting of trifluridine (FTD) and tipiracil hydrochloride (TPI). TAS-102 was found to significantly improve the overall survival of patients with metastatic colorectal cancer who were refractory to treatment with a fluoropyrimidine, irinotecan, and oxaliplatin in a double-blind randomized phase II study. Although significant survival benefits from 5-fluorouracil (5-FU)-based chemotherapy have also been reported in patients with gastric cancer, many patients experience recurrences after several courses of 5-FU-based chemotherapy. The resistance of gastric tumors to 5-FU therapy is thus a major clinical problem. In this study, the efficacy of FTD against 5-FU-resistant human gastric cancer cell lines was investigated. Method: 5-FU-resistant cell lines established by continuously exposing the parent cell lines (MKN-45, MKN-74, and KATOIII) to escalating concentrations (1-5 μM) of 5-FU over a 1-year period were used. The sensitivities of the cell lines to FTD were evaluated using a crystal violet staining assay. To elucidate the mechanism by which resistance is overcome, the mRNA levels of TK1, which converts FTD into an active monophosphate form, and hENT1, which is involved in the cellular uptake of FTD, were determined using RT-PCR. Results: The resistant cell lines KATOIII/5FU, MKN74/5FU, and MKN45/5FU exhibited a 2.0-fold, 4.8-fold, and 14.2-fold resistance to 5-FU, compared with their parent cell lines, respectively. MKN-45/5FU also showed a 3.7-fold resistance to FTD, whereas MKN-74/5FU (1.0-fold) and KATOIII/5FU (1.2-fold) showed no cross-resistance to FTD. The TK1 mRNA level was decreased by 40% in the MKN-45/5FU cells, compared with the parent cell line. Furthermore, this cell line showed a 60% decrease in the mRNA level for hENT1. In contrast, the hENT1 mRNA level increased by 1.6-fold in the KATOIII/5FU cells, with a 50% decrease in the TK1 mRNA level. The TK1 and hENT1 mRNA levels in MKN-74/5FU were increased by 1.9-fold and 1.7-fold, respectively. Conclusion: FTD was able to overcome the resistance to 5-FU in 2 out of 3 resistant cell lines in vitro, with MKN45/5FU exhibiting a partial cross-resistance to FTD. These results suggest that TAS-102 might be a promising chemotherapeutic agent for the treatment of gastric cancer relapses after 5-FU-based treatment. Furthermore, TK1 and hENT1 might be involved in FTD-related cytotoxicity.

Citation Format: Kazuaki Matsuoka, Takashi Kobunai, Teiji Takechi. Efficacy of trifluridine for 5-fluorouracil-resistant human gastric cancer cell lines and their mechanisms. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 781. doi:10.1158/1538-7445.AM2014-781
Abstract 794: The ATR inhibitor VE-821 in combination with the novel topoisomerase I inhibitor LMP-400 selectively kills cancer cells by disabling DNA replication initiation and fork elongation
Authors: Jossé Rozenn , Martin Scott E. , Guha Rajarshi , Ormanoglu Pinar , Pfister Thomas , Morris Joel , Doroshow James H. , Pommier Yves
Published: May 2015

Camptothecin, a specific topoisomerase I inhibitor is a potent anticancer drug, especially against solid tumors. This agent produces well-characterized double-strand breaks upon collision of replication forks with topoisomerase I cleavage complexes. In an attempt to improve its efficacy, we conducted a synthetic lethal siRNA screening using a library that targets nearly 7000 human genes. Depletion of ATR, the main transducer of replication stress-induced DNA damage response exacerbated cytotoxic response to both camptothecin and the indenoisoquinoline LMP-400, a novel class of topoisomerase inhibitors in clinical trial. Inhibition of ATR by the recently developed specific inhibitor VE-821 induced synergistic antiproliferative activity when combined with either topoisomerase inhibitor. Cytotoxicity induced by the combination with LMP-400 was greater than with camptothecin. Using single cell analysis and DNA fiber spread, we show that VE-821 abrogated the S-phase checkpoint, restored origin firing and replication fork progression. Moreover, the combination of a topoisomerase inhibitor with VE-821 inhibited the phosphorylation of ATR and ATR-mediated Chk1 phosphorylation but strongly induced γH2AX. Single cell analysis revealed that γH2AX pattern changed overtime from well-defined focus to a pan-nuclear staining. The change in γH2AX pattern can be useful as a predictive biomarker to evaluate the efficacy of therapy. The key implication of our work is the clinical rationale it provides to evaluate the combination of indenoisoquinoline topoisomerase I inhibitors with ATR inhibitors.

Citation Format: Rozenn Jossé, Scott E. Martin, Rajarshi Guha, Pinar Ormanoglu, Thomas Pfister, Joel Morris, James H. Doroshow, Yves Pommier. The ATR inhibitor VE-821 in combination with the novel topoisomerase I inhibitor LMP-400 selectively kills cancer cells by disabling DNA replication initiation and fork elongation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 794. doi:10.1158/1538-7445.AM2014-794
Abstract 806: Selective killing of cancer cells with mitochondrial respiratory dysfunction induced by activation of oncogenic Ras
Authors: Lu Weiqin , Yang Yaying , Logsdon Craig , Huang Peng
Published: May 2015

Mitochondrial dysfunction is an important mechanism by which cancer cells become resistant to chemotherapeutic agents. Oncogenic Ras activation is often observed in human cancer and was reported to cause mitochondrial dysfunction by compromising mitochondrial electron transport chain. Therefore, identification of new agents capable of effectively killing mitochondrial defective cancer cells would have important therapeutic implications. Our previous work has discovered that mitochondrial respiratory dysfunction could cause increased NADPH oxidase (NOX) activity to support cell survival in the metabolic switch from mitochondrial oxidative phosphorylation to glycolysis. Mitochondrial respiratory dysfunction can also cause profound redox alteration to adapt ROS stress. Here, we report that targeted inhibition of NOX and glutathione synthesis has synergy effect in killing mitochondrial respiratory dysfunction cells, including cancer cells harboring oncogenic Ras activation. Activation of NOX and increased glutathione antioxidants are always observed in Ras activated cells. Treatment of these cancer cells with DPI and BSO to inhibit NOX activity and antioxidant adaptation function resulted in an elevated ROS stress, increased gamma-H2AX expression, leading to massive death of the cancer cells, such as Panc-1 and HCT116 cells. Antioxidant NAC and catalase attenuated the BSO and DPI induced cell death in mitochondrial respiratory dysfunction cells. The synergistic effect of BSO and DPI to kill oncogenic Ras bearing HCT116 cells was further confirmed using colony formation assay. Our results suggest that DPI, in synergy with BSO, is a promising compound capable of killing cancer cells bearing oncogenic Ras mutations through a ROS-mediated mechanism and warrants further investigations.

Citation Format: Weiqin Lu, Yaying Yang, Craig Logsdon, Peng Huang. Selective killing of cancer cells with mitochondrial respiratory dysfunction induced by activation of oncogenic Ras. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 806. doi:10.1158/1538-7445.AM2014-806
Abstract 823: Water-soluble ureidomustine (BO-1055) potently suppresses orthotopic 22Rv/HL2 prostate tumor xenografts: early preclinical studies
Authors: Su Tsann-Long , Chen Yi-Ren , Shieh Jae-Hung , Tsai Tung-Hu , Moore Malcolm A.S. , Lee Te-Chang
Published: May 2015

In developed countries, prostate cancer (PCa) is one of the leading causes of death in men. PCa often recurs and metastasizes after an initial response to hormone therapy. Once PCa progresses to the castration-resistant stage, it becomes incurable. New and effective agents against PCa are therefore urgently needed. The objective of this study is to evaluate the antitumor activity of ureidomustine (BO-1055), which is a chemically stable and water-soluble phenyl N-mustard-benzamide conjugate previously synthesized from our laboratory. We previously demonstrated that ureidomustine exhibited potent therapeutic efficacy in nude mice bearing various human tumor xenografts, such as human colon cancer HCT-116 and prostate adenocarcinoma PC-3 xenografts (subcutaneous implantation), inhibiting growth by >95% and >99%, respectively. To broaden the antitumor spectrum of this agent, we evaluated the therapeutic efficacy of ureidomustine in nude mice bearing 22Rv/HL2 human PCa tumors implanted at an orthotopic site. The results showed that ureidomustine was as efficacious as docetaxel (>92% tumor suppression) and more potent than carboplatin (62% suppression) against 22Rv/HL2 PCa tumors in an orthotopic xenograft model. It revealed that ureidomustine exhibited low toxicity in mice, with no apparent pathological changes. We also studied the cytotoxicity of ureidomustine against normal murine cells and human hematopoietic stem cells (cord blood CD34+). The results showed that this agent exhibited low cytotoxicity against human hematopoietic stem cells (cord blood CD34+), primary human endothelial cells, and mesenchymal stem cells (BSC). Moreover, we performed the early preclinical studies including pharmacokinetics in rats, rat plasma protein binding, metabolic stability in rat liver microsomes, the 14 day intravenous acute toxicity in mice, and the biodistribution in rat, to determine whether this agent is a candidate for future clinical studies. The results indicate that ureidomustine is as potent as docetaxel against 22Rv/HL2 PCa cells in orthotopic xenograft models with low toxicity. In addition, this agent has low toxicity to human hematopoietic stem/progenitor cells and stromal cells such as BM-derived endothelial cells (BMEC) and MSC. Furthermore, early preclinical studies (ADME) suggest that ureidomustine has high potential for the treatment of advanced PCa in the clinic.

Citation Format: Tsann-Long Su, Yi-Ren Chen, Jae-Hung Shieh, Tung-Hu Tsai, Malcolm A.S. Moore, Te-Chang Lee. Water-soluble ureidomustine (BO-1055) potently suppresses orthotopic 22Rv/HL2 prostate tumor xenografts: early preclinical studies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 823. doi:10.1158/1538-7445.AM2014-823
Abstract 825: The development of a novel PARP inhibitor with potent antitumor activity in various tumor xenograft models
Authors: Park Ji-Seon , Kim Jang-Hyun , Cheon Kwang-Woo , Cho Bo-Young , Kim Kang-Jeon , Lee Han-Chang , Kim Young-Cheol , Oh Hyung-Chan , Lee Hyun-Ho , Kim Jeong-Min
Published: May 2015

Poly (ADP-ribose) Polymerase (PARP) plays a critical role in DNA repair processes. Small molecule inhibitors of PARP for the treatment of cancer are currently being investigated either single agents or in combination therapy with other DNA damaging agents. Based on recent published data, PARP inhibitors have shown promising results as a powerful therapeutic anticancer agents, especially in tumors deficient in BRCA-1or BRCA-2 function. In this study, we present a novel synthetic inhibitor of poly (ADP-ribose) polymerase (PARP) for their anti-tumor activity in various types of tumor xenograft model. Among new synthetic PARP inhibitors, JPI-283 shows synergistic effects in vitro cell cytotoxicity with DNA damaging agent such as Temozolomide(TMZ), SN-38, and CDDP. Also, JPI-283 represents a potential anticancer activity in BRCA-1 and BRCA-2 mutant cells as a single agent. In tumor xenograft model studies, the combination of JPI-283 with TMZ by oral dosing results in more than 60-70% tumor growth inhibition rate, compared to the control group in CAPAN-1, U87MG, MDA-MB-468 and SW620 tumor xenograft model. In addition, the combination of JPI-283 with CDDP shows superior antitumor activity compared to that of AZD2281 with CDDP in MDA-MB468 triple negative breast tumor xenograft model. The pharmacokinetics of JPI-283 in mouse and rat shows over 50% bioavailability. These findings suggest that JPI-283 would be an attractive therapeutic candidate for the treatment of cancer including DNA repair deficient cancer.

Citation Format: Ji-Seon Park, Jang-Hyun Kim, Kwang-Woo Cheon, Bo-Young Cho, Kang-Jeon Kim, Han-Chang Lee, Young-Cheol Kim, Hyung-Chan Oh, Hyun-Ho Lee, Jeong-Min Kim. The development of a novel PARP inhibitor with potent antitumor activity in various tumor xenograft models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 825. doi:10.1158/1538-7445.AM2014-825
Abstract 837: The unique profile of microtubule stability initiated by the taccalonolides leads to potent antitumor activities
Authors: Risinger April L. , Li Jing , Peng Jiangnan , Bennett Melissa J. , Rohena Cristina C. , Schriemer David C. , Mooberry Susan L.
Published: May 2015

The taccalonolides are structurally distinct microtubule stabilizers purified from the roots and rhizomes of plants of the genus Tacca. The taccalonolides impart a unique mechanism of microtubule stabilization through covalent attachment to the 212-230 peptide of β-tubulin. The profound interprotofilament stability conferred by taccalonolide binding, as demonstrated by hydrogen deuterium exchange mass spectrometry, occurs independent of changes in the H7 or M-loops, which makes their effects different from other classes of microtubule stabilizers. This remarkable stability results in the formation of microtubules that are highly resistant to cold induced depolymerization or mechanical disruption. The covalent attachment of the taccalonolides to microtubules is proposed to be directly responsible for their strong cellular persistence and ability to circumvent multiple mechanisms of clinically relevant drug resistance, including expression of P-glycoprotein.

We have isolated and characterized 66 new taccalonolides that range in potency from 0.37 nM to over 50 µM, allowing for detailed structure activity relationship studies. These studies demonstrate that epoxidation of the C22,23 double bond present in most naturally occurring taccalonolides is optimal for potency. A simple, one step oxidation reaction has been employed and increases the potency of 17 natural taccalonolides by as much as 700-fold. The new, potent taccalonolides show excellent antitumor activity against the MDA-MB-231 triple negative breast cancer xenograft model at cumulative doses as low as 0. 5 mg/kg. This exquisite in vivo potency facilitates antitumor evaluations from small quantities of material and allows administration in aqueous vehicles. Studies to further map the optimal interactions of the taccalonolide backbone with microtubules and identify a candidate for clinical development are in progress.

Citation Format: April L. Risinger, Jing Li, Jiangnan Peng, Melissa J. Bennett, Cristina C. Rohena, David C. Schriemer, Susan L. Mooberry. The unique profile of microtubule stability initiated by the taccalonolides leads to potent antitumor activities. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 837. doi:10.1158/1538-7445.AM2014-837
Abstract 844: Contribution of dual oxidase 2 (DUOX2) to hyper radiosensitivity in human gastric cancer cells
Authors: Nguyen Duc , Chang Elizabeth , Sharma Navesh , Carrier France
Published: May 2015

Whole abdominal radiotherapy (WART) is a primary method for managing gastrointestinal cancers that have disseminated into intra-abdominal tissues. While effective, this approach is limited since combination of WART with full-dose chemotherapy regimens increase toxicity to normal tissue. Recent studies have demonstrated a survival advantage in a novel treatment paradigm that allows for the safe use of full-dose systemic chemotherapy in combination with Low Dose Fractionated Radiotherapy (LDFRT). Traditionally, radiotherapy used doses greater than 120 cGy because it was thought that lower radiation doses would be ineffective for tumor therapy. We now know that LDFRT can produce hyper-radiosensitivity (HRS), a phenomenon where cells undergo apoptosis at radiation doses as low as 15 cGy, in a number of proliferating cells. Here we aimed at determining whether LDFRT can induce HRS in gastrointestinal cancer cells and at identifying biomarkers of chemopotentiation by LDFRT. Our data indicate that three consecutive daily fractions of 15 cGy produced HRS in gastric cancer cells and potentiated a modified regimen of Docetaxel, Cisplatin, and 5’-fluorouracil (mDCF). Colony survival assays indicated that 15 cGy was sufficient to kill 90% of the cells when LDFRT was combined with mDCF whereas an almost ten times higher dose (135 cGy) was needed to achieve the same rate when using conventional radiotherapy alone. RT2 PCR Profiler Array analysis indicated that this combined regimen up-regulated dual oxidase 2 (DUOX2), an enzyme functioning in the production of hydrogen peroxide, without up-regulating genes involved in DNA repair. Moreover, down regulation of DUOX2 increased radiation resistance at every radiation doses tested. In addition, a subset of genes known to be activated by Reactive Oxygen Species were specifically upregulated by LDFRT when combined with mDCF. Taken together these data suggest that chemopotentiation by LDFRT in gastric cells may be due, at least in part, to increased ROS production (DUOX2) without upregulation of the DNA repair machinery. These data thus provide a rationale for further explorations of potential clinical applications of LDFRT, such as in WART, as chemopotentiator for advanced and metastatic gastric cancers.

Citation Format: Duc Nguyen, Elizabeth Chang, Navesh Sharma, France Carrier. Contribution of dual oxidase 2 (DUOX2) to hyper radiosensitivity in human gastric cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 844. doi:10.1158/1538-7445.AM2014-844
Abstract 851: Gold nanoparticle-mediated infrared hyperthermia reduces the radiotherapy dose required for tumor therapy
Authors: Hainfeld James F. , O'Connor Michael J. , Lin Lynn , Slatkin Daniel N. , Dilmanian F. Avraham , Smilowitz Henry M.
Published: May 2015

Gold nanoparticles (AuNPs) absorb light and can be used to heat and ablate tumors. The “tissue window” at ∼800 nm (near infrared, NIR) is optimal for best tissue penetration (∼2cm). Previously large, 50-150nm gold nanoshells and nanorods that absorb well in the NIR have been used. Here we show that small AuNPs, that may penetrate tumors better, barely absorb at 800nm. However, when conjugated to antitumor antibodies, they are taken up by tumor cells, which catalytically aggregate them by enzyme degradation and pH effects, thus shifting their absorption to the NIR region thereby amplifying their photonic absorption. The AuNPs are NIR transparent until they accumulate in tumor cells; this reduces background heating in blood and non-targeted tissues thereby increasing specificity in contrast to constructs that are always NIR absorbing. We show that treatment of subcutaneous EGFR overexpressing human squamous cell carcinoma (A431) tumor xenografts with 15nm AuNPs conjugated with anti-EGFR and NIR resulted in complete tumor ablation with virtually no normal tissue (skin) damage. Further, using radioresistant mouse squamous cell carcinoma SCCVII xenografts, we have combined AuNP-mediated infrared heating with x-ray therapy to take advantage of the well-known synergy of hyperthermia and radiotherapy. Lipoic Acid modified 15nm AuNPs were injected intratumorally by convection-enhanced delivery (CED) followed by NIR and X-ray therapy. It was found that the dose required for control of 50% the tumors, 55Gy, could be reduced to <15Gy, a factor of 3.7 less. AuNPs therefore provide a method to use hyperthermia to reduce the x-radiation needed for tumor control, thereby sparing normal tissue, reducing side effects and making radiotherapy more effective.

Citation Format: James F. Hainfeld, Michael J. O'Connor, Lynn Lin, Daniel N. Slatkin, F. Avraham Dilmanian, Henry M. Smilowitz. Gold nanoparticle-mediated infrared hyperthermia reduces the radiotherapy dose required for tumor therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 851. doi:10.1158/1538-7445.AM2014-851