bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2473: Combined BET-bromodomain and CDK2 inhibition in MYC-driven medulloblastoma
Authors: Bolin Sara , Borgenvik Anna , Persson Camilla , Rosén Gabriela , Sundström Anders , Qi Jun , Bradner James E. , Weiss William A. , Cho Yoon-Jae , Weishaupt Holger , Swartling Fredrik J.
Published: July 2016

Misexpression of MYC genes (MYC and MYCN) occurs commonly in medulloblastoma (MB), the most frequent malignant childhood brain tumor. We previously showed that tumors are addicted to MYCN and that MYCN stabilization is required for MB development in mice (Swartling et al, Genes & Dev, 2010; Cancer Cell, 2012). Targeted MYCN suppression completely depleted MYCN-driven MB cells in vivo. Immediate transcriptional changes from such MYCN blockade were found by RNA-Seq and showed similarities to changes that occurred after CDK2 suppression or when inhibiting BET bromodomains. CDK2 and BET inhibitors both inhibited MYC protein expression and effectively induced cell cycle arrest or apoptosis. Compared with either agent alone a sustained combination treatment over 7-10 days displayed synergy and effectively abolished tumor cell proliferation in vitro. The combined treatment further reduced tumor growth in orthotopical MB transplants and significantly prolonged survival as compared to single agent therapy. Our data suggest that dual inhibition of CDK2 and BET Bromodomains could be a novel treatment approach in suppressing medulloblastoma by targeting MYC proteins.

Citation Format: Sara Bolin, Anna Borgenvik, Camilla Persson, Gabriela Rosén, Anders Sundström, Jun Qi, James E. Bradner, William A. Weiss, Yoon-Jae Cho, Holger Weishaupt, Fredrik J. Swartling. Combined BET-bromodomain and CDK2 inhibition in MYC-driven medulloblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2473.
Abstract 2481A: A novel chemically-modified curcumin (CMC 2.24) promotes chemosensitivity in neuroblastoma
Authors: Tauber David , Galinski Basia , Castellanos Raquel , Scaduto Joseph , Johnson Francis , Golub Lorne , Weiser Daniel A.
Published: July 2016

Introduction

The chemically modified curcumin, CMC 2.24 (TRB-N0224, Traverse Biosciences Inc.), was designed to overcome the poor solubility, bioavailability, and biological potency of naturally occurring curcumin in an effort to achieve superior safety and efficacy in chronic inflammatory conditions and cancer. It has been demonstrated that CMC 2.24 can sensitize cancer cells that are otherwise refractory to chemotherapy. Patients with neuroblastoma, a highly lethal childhood cancer of the peripheral sympathetic nervous system, often have de novo chemotherapy resistance and therefore succumb rapidly to their disease. We hypothesize that chemoresistance in primary refractory neuroblastoma is mediated by anti-apoptotic mechanisms that can be overcome when conventional therapy is combined with CMC 2.24.

Experimental Procedures

A heterogeneous panel of neuroblastoma cell lines was cultured under routine conditions and subjected to varying concentrations of CMC 2.24 to establish IC50s. Subsequent studies were focused on NB-EBc1, a MYCN non-amplified cell line, and IMR-5, a MYCN amplified cell line. IC50s were also generated for cisplatin as a single agent, and then when administered in combination with CMC 2.24. Whole protein cell lysates were extracted at 24, 48, and 72 hours after treatment and cell viability was measured by MTT proliferation assays.

Results

Proliferation defects were observed in all neuroblastoma cell lines treated with CMC 2.24 as compared to vehicle (DMSO) control. Relatively cisplatin-resistant cell lines had diminished cell viability when CMC 2.24 was added in combination with cisplatin, suggesting a synergistic effect. Alterations in response to CMC 2.24 treatment occur in anti-apoptotic proteins survivin and BARD1, found to be upregulated in chemoresistant cell lines. Additional mechanistic evaluation is ongoing.

Conclusions

There is no known curative therapy for patients with primary refractory neuroblastoma. CMC 2.24 enhances chemosensitivity in a panel of neuroblastoma cell lines and may provide a new therapeutic approach that can overcome de novo chemotherapy resistance. Further mechanistic and in vivo studies are needed to facilitate clinical development of a promising novel anti-cancer agent.

Citation Format: David Tauber, Basia Galinski, Raquel Castellanos, Joseph Scaduto, Francis Johnson, Lorne Golub, Daniel A. Weiser. A novel chemically-modified curcumin (CMC 2.24) promotes chemosensitivity in neuroblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2481A.
Abstract 257: Evaluation of organic cation transporter 1 (OCT1, SLC22A1) as transporter for sorafenib
Authors: Neul Claudia , Baker Sharyn D. , Sparreboom Alex , Schaeffeler Elke , Laufer Stefan , Schwab Matthias , Nies Anne T.
Published: July 2016

The multikinase inhibitor sorafenib is approved for the treatment of advanced clear-cell renal and hepatocellular carcinomas, yet, patients’ survival is prolonged for only several months (Wilhelm et al., Mol Cancer Ther 2008). The understanding of this poor efficacy remains incomplete. One reason for treatment failure may be the high interindividual variability in pharmacokinetics of the orally-given sorafenib. Membrane transporters may contribute to pharmacokinetics of sorafenib and its metabolites as recently reported for the hepatic solute carrier (SLC) organic anion transporter family member 1B1 (OATP1B1) and OATP1B3 (Zimmerman et al, Clin Cancer Res 2013). In contrast, the role of organic cation transporter 1 (OCT1), which is also a major hepatic uptake transporter (Nies et al, Handb Exp Pharmacol 2011), for cellular uptake of sorafenib is controversial (Hu et al, Clin Cancer Res 2009; Swift et al, Drug Metab Dispos 2013; Herraez et al, Hepatology 2013). We therefore sought to comprehensively elucidate the impact of OCT1 on cellular sorafenib uptake by using a combination of different in vitro cell culture models and in vivo approaches involving experiments with Oct1 knockout (-/-) mice. Firstly, we analyzed cellular accumulation of radiolabeled sorafenib by the mammalian cell line HEK293 stably expressing OCT1. Despite overexpression of a functional OCT1 transporter, cellular uptake of neither sorafenib nor its active metabolite sorafenib N-oxide was increased. Next, we studied sorafenib and sorafenib N-oxide pharmacokinetics in mice with a homozygous genetic deletion of the Oct1 transporter. The deficiency of Oct1 had no influence on plasma and hepatic sorafenib and sorafenib N-oxide concentrations. Finally, we investigated sorafenib transport into the human hepatocellular carcinoma cell lines HepG2 and HuH7. Although neither OCT1 mRNA nor protein was detected, a considerable cellular accumulation of sorafenib was observed in both cell lines. Expression profiling of a panel of 55 relevant SLC drug uptake transporters identified several potential novel candidates mediating sorafenib accumulation.

We conclude from these findings that cellular uptake of sorafenib and sorafenib N-oxide is independent of OCT1 and that other, as yet unidentified, transport mechanisms are responsible for cellular sorafenib uptake.

Supported by the Robert Bosch Foundation, Stuttgart, Germany and the ICEPHA Grant Tübingen-Stuttgart, Germany.

Citation Format: Claudia Neul, Sharyn D. Baker, Alex Sparreboom, Elke Schaeffeler, Stefan Laufer, Matthias Schwab, Anne T. Nies. Evaluation of organic cation transporter 1 (OCT1, SLC22A1) as transporter for sorafenib. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 257.
Abstract 2611: Effects of chalcones, nicotinamide, and resveratrol on PPAR gamma activation in oral cancer cells
Authors: Diaz Jennifer , Wuertz Beverly , Galbraith Art , Ondrey Frank G.
Published: July 2016

Several classes of natural products have cancer prevention potential and PPAR gamma is an intriguing chemoprevention target as a nuclear receptor that controls multiple growth and differentiation processes. We have previously tested many classes of natural products in A/J mice and have found that the following chemoprevention compounds had no significant dietary toxicities: inositol, eucalyptol, chalcones, nicotinamides, and resveratrol. We tested these compounds for their capacity to activate PPAR gamma reporter genes in CA-9-22 oral cancer cells. In several repeated experiments we found that Inositol hexaphosphate did not activate PPAR gamma reporter genes at high concentrations of 1-4 mM. We found that eucalyptol, trans-Chalcone, 4 methoxy chalcone, Nicotinic Acid, and Nicotinamide had the capacity for statistically significant activation of PPAR gamma reporter genes in oral cancer cells from 20-60% at concentrations of 1-100 uM. We found that resveratrol was the most potent agent and could activate PPAR gamma reporter genes 2 fold. As a reference, this was about half the activity of the prototypic PPAR gamma activator pioglitazone. We performed additional experiments with resveratrol and found that it could activate the PPAR gamma dependent squamous differentiation gene Involucrin in oral cancer cells and BEAS 2B cells. Additionally, resveratrol significantly decreased BEAS 2 B proliferation from 48-96 hours at concentrations of 10 uM. From this data we conclude that resveratrol has the capacity to activate PPAR gamma in vitro and resveratrol and its derivatives may also function as PPAR gamma activators as an additional mechanism of action. We also conclude that inositol, eucalyptol, chalcones, and nicotinamides do not activate PPAR gamma.

Citation Format: Jennifer Diaz, Beverly Wuertz, Art Galbraith, Frank G. Ondrey. Effects of chalcones, nicotinamide, and resveratrol on PPAR gamma activation in oral cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2611.
Abstract 263: Epicatechin protects from doxorubicin induced cardiotoxicity without affecting its cytotoxic profile in breast cancer cells
Authors: Alshehri Ohoud Y. , Al-Abbasi Fahad A. , El-Bassossy Hany M. , Abdallah Hossam M. , Al-Abd Ahmed M.
Published: July 2016

Doxorubicin is an effective anthracycline anticancer agent for breast cancer despite its dose-limiting cardiovascular toxicity. Epicatechin is a flavonoid compound with potent antioxidant activity.. The purpose of this study is to investigate the influence of epicatechin on the cytotoxic profile of doxorubicin in breast cancer cell lines on the top of ameliorating doxorubicin induced cardiotoxicity. Rats received doxorubicin (12 mg/kg, single iv injection) with or without epicatechin (12 mg/kg, daily, oral) for 6 days then cardiac electrocardiographic was recorded. Doxorubicin administration induced cardiac ischemia which was reflected by increased QT and QTc intervals (1.76 and 1.8 folds, respectively); and increased heart rate. Epicatechin co-administration completely blocked doxorubicin induced ECG abnormalities. Epicatechin combination significantly decreased the IC50 of doxorubicin from 0.55±0.03 to 0.24±0.01; from 0.7±0.036 to 0.56±0.017, and from 0.07± 0.017 to 0.04±0.014 μM in MCF-7, T47D and MDA-MB-231 breast cancer cell lines, respectively. In addition, epicatechin significantly increased doxorubicin cytotoxicity against MCF-7 cells under hypoxic condition and decreased its IC50 from 8.9±1.2 to 6.0±1.2 μM. In MDA-MB-231, epicatechin significantly blocked p-gp efflux activity and enhanced intracellular accumulation of p-gp probe (rhodamine) by 3-4 folds at concentration range (3-100 μM). Further investigation showed that the combination of doxorubicin with epicatechin significantly increased the concentration of pro-caspase 3 compared to doxorubicin alone in T47D and MDA-MB231 cell lines. Cell death mechanism was further investigated using annexin-V/PI differential staining. Epicatechin combination did not significantly increase the percent of apoptotic or necrotic cells compared to treatment with doxorubicin alone in MCF-7 and MDA-MB-231 cells. In T47D, epicatechin combination with doxorubicin significantly increased cell apoptosis and necrosis compared to doxorubicin treatment alone from 1.5±0.5 to 4.6±0.7% and 8.0±1.7 to 12.8± 7.9%, respectively. In addition, epicatechin combination with doxorubicin decreased pro-caspase-3 concentration from 16.7±1.1 fg/cell to 9.2±2.6 fg/cell. Finally, epicatechin did not affect cell cycle distribution induced by doxorubicin. In conclusion, epicatechin significantly protected from doxorubicin induced cardiotoxicity and marginally improved its cytotoxicity against breast cancer cells.

Citation Format: Ohoud Y. Alshehri, Fahad A. Al-Abbasi, Hany M. El-Bassossy, Hossam M. Abdallah, Ahmed M. Al-Abd. Epicatechin protects from doxorubicin induced cardiotoxicity without affecting its cytotoxic profile in breast cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 263.
Abstract 2805: Protein oxidation in pancreatic neoplasia and cancer
Authors: Schultz Michelle , Diaz Andrew , Smite Sharon , DeCant Brian , Bentrem David , Grippo Paul
Published: July 2016

Rationale- Peroxiredoxin-1 (Prdx1) is overexpressed in pancreatic cancer patient serum and correlates with worse prognosis. Prdx1 is an important antioxidant protein whose deletion causes the formation of malignant lesions in mice. Prdx1's redox function depends on its reduction by two other Thioredoxin system members, Thioredoxin (Txn) and Sulfiredoxin (Srxn). Prdx1 may also contribute to tumorigenesis by oligomerizing and becoming a nuclear chaperone when it's overoxidized and its redox function is inhibited.

Objective- Our objective was to investigate disruptions in the Txn system during pancreatic neoplasia and to determine how that affects phosphorylation of Kras effectors.

Findings- Prdx1 expression was elevated and Srxn expression was reduced in pancreatic lesions of El-Kras, Pdx1-Cre/LSL-Kras (KC-Pdx1), and P48-Cre/LSL-Kras (KC-P48) mice. Txn was absent in lesions of KC-Pdx1 and KC-P48 mice but present and differentially located in EL-Kras lesions. In primary pancreatic acinar cells, oxidation of the Txn system with auranofin increased ERK and AKT phosphorylation in EL-Kras mice, but not in KC-P48 mice, indicating differential regulation of the Txn system in KC-P48 mice. This could be due to the presence of a higher molecular weight Prdx1 being present in KC-p48 mice and not in EL-Kras mice. This suggests that the effect of mutant Kras on the thioredoxin system in these two models may be different. Prdx1 and (p)ERK also interacted in vitro and inhibition of ERK and AKT phosphorylation modified the expression of Txn and Srxn in pancreatic cell lines. We also found that in human pancreatic cancer patient tissue, Prdx1 was overexpressed in pancreatic cancer as compared to adjacent normal tissue.

Conclusions- The Txn system is disrupted during pancreatic neoplasia and may be associated with modified ERK and AKT regulation in Kras mutant pancreatic tissue.

Citation Format: Michelle Schultz, Andrew Diaz, Sharon Smite, Brian DeCant, David Bentrem, Paul Grippo. Protein oxidation in pancreatic neoplasia and cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2805.
Abstract 2813: The synergistic anticancer activity of 1’-acetoxychavicol acetate and sodium butyrate in human hepatocellular carcinoma cells
Authors: Matsui-Yuasa Isao , Kojima-Yuasa Akiko
Published: July 2016

Introduction: It has been suggested that the combined effect of natural products may improve the effect of treatment against the proliferation of cancer cells. We evaluated the combination of 1’-acetoxychavicol acetate (ACA), obtained from Alpinia galangal, and sodium butyrate (NaB), a major short chain fatty acid, on the growth of HepG2 cells. ACA exhibits chemopreventive effects on chemically induced tumors in mouse skin as well as on rat oral, colonic, esophangeal, and pancreatic tumors. ACA also exerts antitumor activity by inducing apoptosis in various tumor cells. On the other hand, sodium butyrate has multiple effects on tumor cells cultured in vitro, including, most notably, inhibition of cell proliferation and induction of apoptosis, as well as initiating the differentiation of various carcinoma cells. The aim of our study was to elucidate the synergistic interaction of ACA and NaB on cell viability in the human hepatocellular carcinoma cell line HepG2 and to examine the mechanism of the anti-cancer effect of combined ACA and NaB treatment.

Methods: HepG2 cells or HT-29 cells were cultured in Dulbecco's modified Eagle's medium supplemented with 10% FBS.

Results: The number of HepG2 cells was synergistically decreased via apoptosis induction with the combined treatment of ACA and NaB. In ACA- and NaB-treated cells, intracellular reactive oxygen species (ROS) levels and NADPH oxidase activities were increased significantly. The decrease in cell number after combined treatment of ACA and NaB was improved with the treatment of catalase. These results suggest that an increase in intracellular ROS levels is involved in cancer cell death. AMP-activated protein kinase (AMPK) plays an essential role in controlling processes related to tumor development. In ACA- and NaB-treated cells, AMPK phosphorylation was induced significantly, and this induction improved when cells were pretreated with catalase. These results suggest that the increase in intracellular ROS is involved in the increase of AMPK phosphorylation.

Conclusion: These findings are consistent with the hypothesis that combination treatments can sensitize cancer cells more effectively than individual treatments. We reported that combination treatment of ACA and NaB synergistically induced apoptotic cell death via an increase in intracellular ROS and an increase in pAMPK levels. Our findings may provide new insight into the development of novel combination therapies against hepatocellular carcinoma.

Citation Format: Isao Matsui-Yuasa, Akiko Kojima-Yuasa. The synergistic anticancer activity of 1’-acetoxychavicol acetate and sodium butyrate in human hepatocellular carcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2813.
Abstract 2834: Antitumor effect of AGM 130 (5’-OH-5-nitro-Indirubin oxime), a cyclin-dependent kinase inhibitor in colorectal cancer cells
Authors: Shim Hyun-Jeong , Hwang Jun-Eul , Bae Woo-Kyun , Park Myung-Sook , Yun Hyo-Jeong , Lee Ji-Hee , Cho Sang-Hee , Chung Ik-Joo
Published: July 2016

The AGM 130 (5’-OH-5-nitro-Indirubin oxime) compound is derived from Indirubin, which is an ingredient of Danggui Longhui Wan and used in traditional Chinese medicine. AGM 130 can inhibit the proliferation of a variety cells by arresting the cell in the G2/M phase of the cell cycle, it is a cyclin-dependent kinase (CDK) inhibitor that has anti-proliferative activity and apoptotic effects on cancer cells. AGM 130 has improved water solubility compared to Indirubin, however still displays a low solubility in biologic fluids and a poor bioavailability. This poor water solubility limits the clinical application of AGM 130 to treat cancer. In this study, we decided to develop and evaluate a SNEDDS (self-nanoemulsifying drug delivery systems) formulation containing AGM130 for improving its solubility, dissolution rate, and bioavailability.

To check the anti-proliferative effect of the AGM 130 compound on colon cancer cell line, we performed the MTT assay with the CT-26 cancer cell. We also performed cell cycle analysis, apoptotic assays and western blotting. The CT-26 cell bearing mice were treated intraperitoneally with AGM 130 loaded PPG-cRGD, 5-fluorouracil (5-FU) or AGM 130 loaded PPG-cRGD combined with 5-FU. We measured tumor volume and tumor progression of each groups.

In vitro, AGM 130 showed significant anti-proliferative activity in CT-26 cell (IC 50, 1.9 μM). Cells treated with AGM 130 showed G2/M cell cycle arrest and also induced apoptosis compared to untreated cells. The western blotting analysis showed that AGM 130 inhibited CKD1/cyclin B1 and also CKD2/cyclin E. The greatest tumor regression (percentage tumor growth inhibition) was observed in the group treated with AGM 130 loaded PPG-cRGD combined with 5-FU. When 5-FU was administrated alone, the anti-tumor effect was inferior to the group treated with AGM 130 loaded PPG-cRGD alone.

These results suggest that intraperitoneal administration of AGM 130 loaded PPG-cRGD inhibits tumor progression in a mouse colon cancer. Thus, AGM 130, a cyclin-dependent kinase inhibitors may provide a new therapeutic approach in the treatment of colon cancer.

Citation Format: Hyun-Jeong Shim, Jun-Eul Hwang, Woo-Kyun Bae, Myung-Sook Park, Hyo-Jeong Yun, Ji-Hee Lee, Sang-Hee Cho, Ik-Joo Chung. Antitumor effect of AGM 130 (5’-OH-5-nitro-Indirubin oxime), a cyclin-dependent kinase inhibitor in colorectal cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2834.
Abstract 285: Disulfiram, a dual MGMT and aldehyde dehydrogenase inhibitor, sensitizes ER-positive breast cancer cells to temozolomide and cyclophosphamide
Authors: Bobustuc George C. , Donohoe Deborah , Holmuhamedov Alisher , Kalkunte Srivenugopal , Konduri Santhi D.
Published: July 2016

Background: O6 methylguanine DNA methyltransferase (MGMT) is overexpressed in a majority of cancers, including breast cancer. MGMT is a DNA repair protein leading to chemo resistance. MGMT expression directly correlates with ER expression and tamoxifen resistance. Aldehyde Dehydrogenase (ALDH) activity, as a progenitor/stem cell marker, while it has been reported to inversely correlate with MGMT expression in other cancers, has also been linked to chemotherapy and radiation resistance.

Methods: We have tested the effect of Antabuse (disulfiram, DSF), as a dual MGMT and ALDH inhibitor, at nontoxic doses, in combination with Temozolomide (TMZ) or/and Cyclophosphamide (CP) on ER+ breast cancer cells.

Results: DSF at very low doses (achievable in human serum with standard DSF clinical dosing) decreases ER+ breast cancer cell growth (MCF7, T47D and ZR75) in a dose-dependent manner. DSF further sensitizes breast cancer cells to TMZ or/and CP and significantly inhibits breast cancer growth without causing unwanted side effects on the normal breast epithelial cells. Dose effect and isobologram studies confirm synergistic activity of DSF + CP and moderate synergism for DSF + TMZ. DSF, alone or in combination with TMZ (DSF ± TMZ) and/or CP (DSF ± CP), significantly inhibits expression of MGMT, aldehyde dehydrogenase, ERα, E2F and BIRC5 gene (survivin) - all involved in breast cancer tumorigenesis. DSF, alone or in combination with TMZ (DSF ± TMZ) and/or CP (DSF ± CP) caused significant apoptosis in breast cancer cells. In a dose dependent manner, DSF inhibited colony formation, effect which was further enhanced by addition of TMZ/CP (DSF ± TMZ/CP). Similarly, DSF alone or in combination with TMZ (DSF ± TMZ) and/or CP (DSF ± CP) decreased the metastatic potential of breast cancer cells.

Conclusions: Our findings suggest that DSF as dual inhibitor of MGMT and ALDH significantly enhances the antitumor effect of alkylators as CP and TMZ in ER+ breast cancer

Citation Format: George C. Bobustuc, Deborah Donohoe, Alisher Holmuhamedov, Srivenugopal Kalkunte, Santhi D. Konduri. Disulfiram, a dual MGMT and aldehyde dehydrogenase inhibitor, sensitizes ER-positive breast cancer cells to temozolomide and cyclophosphamide. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 285.
Abstract 2970: MEDI4276, a HER2-targeting antibody tubulysin conjugate, displays potent in vitro and in vivo activity in preclinical studies
Authors: Li John , Toader Dorin , Perry Samuel R. , Muniz-Medina Vanessa , Wetzel Leslie , Rebelatto Marlon C. , Masson Hinrichs Mary Jane , Fleming Ryan , Bezabeh Binyam , Thompson Pamela , Dimasi Nazzareno , Lam Brandon , Yu Xian-Qing , Gao Changshou , Dixit Rakesh , Coats Steven , Osbourn Jane , Wu Herren
Published: July 2016

Antibody drug conjugates (ADCs) combine the specificity of antibodies with the potent cytotoxicity of small molecule drugs and have shown to provide therapeutic options for various cancers. We report herein the discovery of a HER2-targeting ADC MEDI4276 that showed potent cell killing activity in vitro in cancer cell lines that express the HER2 receptor. The observed in vitro activity translated into in vivo tumor growth inhibition in various xenograft mouse models. MEDI4276 is a homogeneous molecule with precise control of drug loading following site specific conjugation of a cytotoxic drug. The drug in MEDI4276 is MMETA, a fully synthetic analog of the tubulysin family that showed pM potency in a panel of cancer cell lines. MMETA was conjugated to the antibody via engineered cysteines with a maleimide-bearing mc-Lys protease cleavable linker. The antibody in MEDI4276 is a bivalent biparatopic antibody targeting two distinct non-overlapping epitopes on HER2 that leads to antibody-receptor clustering following binding and thus promoting internalization, lysosomal trafficking and degradation. The combination of enhanced internalization and potent cytotoxic drug allows for this ADC to kill tumor cell populations with a broader range of HER2 expression. Preclinical studies showed that MEDI4276 induced tumor regression in HER2-positive tumor models that had developed acquired resistance to T-DM1 and in a number of models with lower HER2 expression that are refractory to T-DM1 treatment. Overall, our findings underscore the potential application of MEDI4276 to treat a large patient population that is ineligible for or relapsed/refractory to current HER2-targeted therapies. MEDI4276 is currently being investigated in a Phase I clinical trial.

Citation Format: John Li, Dorin Toader, Samuel R. Perry, Vanessa Muniz-Medina, Leslie Wetzel, Marlon C. Rebelatto, Mary Jane Masson Hinrichs, Ryan Fleming, Binyam Bezabeh, Pamela Thompson, Nazzareno Dimasi, Brandon Lam, Xian-Qing Yu, Changshou Gao, Rakesh Dixit, Steven Coats, Jane Osbourn, Herren Wu. MEDI4276, a HER2-targeting antibody tubulysin conjugate, displays potent in vitro and in vivo activity in preclinical studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2970.
Abstract 2973: CD269 - A promising target for amanitin based ADCs
Authors: Palfi Aniko , Hechler Torsten , Mueller Christoph , Pahl Andreas , Kulke Michael
Published: July 2016

Antitumor 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. Heidelberg Pharma focuses on Amanitin, the most well-known toxin of the amatoxin family. Amanitin binds to the eukaryotic RNA pol II and thereby inhibits the cellular transcription at very low concentrations.

In the current study, in vitro and in vivo Data of Amanitin-ADCs targeting CD269 (B cell maturation antigen) are presented. CD269 is expressed on cells of the B cell lineage, predominantly on plasma blasts and plasma cells. It is not expressed on naïve B cells, germinal center B cells and memory B-cells (Darce et al. (2007) J Immunol 179:7276-7286). CD269 is highly expressed on malignant plasma cells like multiple myeloma, a B cell non Hodgkin lymphoma of the bone marrow (Novak et al. (2004) Blood 103:689-94). Since multiple myeloma is a usually incurable malignancy of plasma cells, new therapies are urgently needed. Using ADCs in the cure of multiple myeloma could be a promising approach, especially by using a toxin whose mode of action was not applied before, like amanitin based ADCs.

In vitro data of anti-CD269-amanitin ADC showed cytotoxicity on CD269 positive cell lines in picomolar range, while up to micromolar concentrations, no cytotoxic activity on CD269 negative cells was observed. In mouse xenograft models, anti-CD269-amanitin showed clear anti-tumorigenic potential. A comprehensive data package will be presented.

Citation Format: Aniko Palfi, Torsten Hechler, Christoph Mueller, Andreas Pahl, Michael Kulke. CD269 - A promising target for amanitin based ADCs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2973.
Abstract 2995: Mechanisms of high dose ascorbate inhibiting pancreatic cancer growth and metastasis
Authors: Chen Qi , Polireddy Kishore , Dong Ruochen , Chen Ping
Published: July 2016

Purpose:

High-dose intravenous ascorbate (IVC) bypasses bioavailability barriers of oral ingestion and provides pharmacologic concentrations in tissues, and exhibits pro-oxidant anti-cancer activities. In pancreatic cancer pre-clinical models, ascorbate has been shown to sensitize the tumor to the 1st line chemotherapeutic drug gemcitabine. Here, we investigated the possible mechanisms of actions of ascorbate on pancreatic cancer growth and metastasis.

Methods

Orthotopic pancreatic cancer mouse model was utilized for evaluation of the effects of ascorbate in inhibiting tumor growth and metastasis. Molecular biological approaches were used in investigation the mechanisms of these effects.

Results

In the orthotopic mouse tumor model, ascorbate treatment alone decreased pancreatic cancer growth and metastasis. Ascorbate treatment enhanced expressions of epithelial markers and suppressed expression of mesenchymal markers in pancreatic cancer cells. MMP-2 expression and activity were decreased dose-dependently. Tumor tissues from ascorbate-treated mice had markedly increased collagen and desmoplasia in the extracellular matrix. Such fibrosis was not seen in normal tissues from the same mouse. In addition, ascorbate decreased the protein level of deacetylase HDAC6, and inhibited activity of the deacetylase Sirt-2 through depletion of NAD+. As a result, ascorbate robustly increased α-tubulin acetylation in pancreatic cancer cells. Acetylation promoted tubulin polymerization and stabilization, mimicking the cellular outcome of paclitaxel, resulted in inhibition of cell motility and mitosis.

Conclusion

Pharmacological concentrations of ascorbate affected pancreatic tumor cells and the tumor microenvironment, led to inhibition of tumor growth and metastasis.

Citation Format: Qi Chen, Kishore Polireddy, Ruochen Dong, Ping Chen. Mechanisms of high dose ascorbate inhibiting pancreatic cancer growth and metastasis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2995.
Abstract 3207: Influence of tumor mutation burden on response to anti-PD-1 treatment in murine models of melanoma
Authors: Galvani Elena , Hogan Kate , Gremel Gabriela , Viros Amaya , Mandal Amit K. , Smith Matthew , Swan Jacqueline , Banyard Antonia , Ashton Garry , Dhomen Nathalie , Marais Richard
Published: July 2016

Therapeutic antibodies directed against immune checkpoints, such as cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death-1 (PD-1), have recently shown remarkable clinical benefits, particularly in metastatic melanoma and non-small cell lung cancer (NSCLC), cancers largely caused by chronic exposure to mutagenic agents. Recent studies have focused on identifying genomic and immune predictors of response, but consistent, robust biomarkers have yet to be fully characterized. However, some data suggests a high non-synonymous tumour mutation burden is associated with clinical benefit in melanoma patients who received anti-CTLA-4 therapy. A similar correlation was also found in NSCLC patients treated with anti-PD-1.

Using mouse models of BRAFV600E-driven melanoma, we examined the relationship between tumour mutation burden and response to the immune checkpoint inhibitor anti-PD-1. Chronic exposure to ultraviolet radiation (UVR) was used to increase the number of tumour non-synonymous single nucleotide variants (SNVs), and thus mutational load. Responses to PD-1 blockade were compared between tumours having low (∼10 SNVs) and high (>100 SNVs) mutation burden and tumours were subsequently subjected to comprehensive molecular and immune profiling using whole exome sequencing, immunohistochemistry, and flow cytometry.

Our initial data suggest there is no significant correlation between tumour mutation burden and response in our model of BRAFV600E-driven melanoma, and we will present a detailed analysis of low- and high-mutation burden tumours in light of their response to PD-1 blockade. Consistent with previous studies, our results highlight that integrated molecular characterization of tumour tissue and associated microenvironment in larger cohorts is needed to identify robust determinants of response to immune checkpoint inhibitors.

Citation Format: Elena Galvani, Kate Hogan, Gabriela Gremel, Amaya Viros, Amit K. Mandal, Matthew Smith, Jacqueline Swan, Antonia Banyard, Garry Ashton, Nathalie Dhomen, Richard Marais. Influence of tumor mutation burden on response to anti-PD-1 treatment in murine models of melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3207.
Abstract 3216: Anti-PD-1, Anti-PD-L1 and Anti-CTLA-4 checkpoint inhibitor treatment leads to different responses in syngeneic tumor models
Authors: Jantscheff Peter , Schaefer-Obodozie Cynthia , Moor Sandra , Weber Holger
Published: July 2016

Checkpoint inhibitor treatment has already become a common therapy of various cancer types. Still there is a growing need for well-characterized preclinical mouse models, as clinical data indicate that patients only partially respond to this regiment. We examined the efficacy of anti-CTLA-4, anti-PD-1 and anti-PD-L1 therapy on 4T1, B16.F10, Clone M-3, CT26wt, LL/2, MC38-CEA and RENCA syngeneic tumor models. The outcome demonstrates a large variation in the response to the immune checkpoint therapy among the analyzed tumor models. Poorly immunogenic models like the LL/2 tumor did not respond to any given therapy, whereas highly immunogenic tumor models like CT26wt or MC38-CEA tumors were inhibited by all tested immunotherapies.

The CT26wt tumor model was further characterized in a re-challenge experiment. Growth retardation was observed in CT26wt-tumor bearing mice treated with anti-PD-L1 antibody. A fraction of mice responded with a complete regression of the tumor. These mice were repeatedly challenged subcutaneously with a high number of fresh CT26wt tumor cells. No re-growth of CT26 tumors was observed, whereas challenging with fresh 4T1 tumor cells resulted in a rapid 4T1 growth in these mice, demonstrating a specific immune protection against CT26wt tumors.

In addition all syngeneic tumor models were analyzed for the distribution of immune cells such as Treg cells, M1/M2 macrophages and M/PMN-MDSCs in tumor tissue based on multi-color flow-cytometric analysis.

These data may help to select a suitable model for testing new drug candidates and define a sensitive combination therapy to support the anti-tumor immune defense in addition to checkpoint inhibitor treatment.

Citation Format: Peter Jantscheff, Cynthia Schaefer-Obodozie, Sandra Moor, Holger Weber. Anti-PD-1, Anti-PD-L1 and Anti-CTLA-4 checkpoint inhibitor treatment leads to different responses in syngeneic tumor models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3216.
Abstract 3248: Over-expression of 1-ACBP, B-ACBP and PBR genes in mast cells infiltrating oesophageal squamous cell tumors
Authors: Dlamini Zodwa
Published: July 2016

Oesophageal cancer ranks as the sixth most common malignancy in the world, and recent evidence has shown that its incidence is increasing. ACBPs (Acyl-coA binding proteins) act as intracellular carrier-proteins for medium to long chain acyl-coA, mediating fatty acid transport to the mitochondrion for ß-oxidation. ACBPs are also believed to be putative ligands of PBR (peripheral benzodiazepine receptor), and bound to this receptor facilitate mitochondrial membrane permeabilization giving the notion that favours apoptosis. The main aim of the study was to establish the expression patterns of 1-ACBP, B-ACBP, and PBR in oesophageal cancer, and to link their roles with the disease. Probes specific to the genes encoding 1-ACBP, B-ACBP, and PBR were PCR amplified and cloned into pGEM-T easy vectors using gene specific primers. The cloned products were sequenced and screened against the GENBANK database (NCBI) to verify the identity and orientation of cloned products within the vector. Antisense and sense probes were then generated using T7 or SP6 RNA polymerase after digestion with either Pst1 or Apa1, respectively. In situ hybridization and quantitative real-time PCR methods were performed to determine localization and the expression levels of the three genes in oesophageal cancer. All three genes illustrated substantial up-regulation within the malignant tissue sections as compared to normal oesophageal sections, all three transcripts localized specifically to plasma cells and lymphocytes in diseased and normal tissue section. In the diseased tissue B-ACBP and 1-ACBP mRNA localized to endothelial cells of blood vessels in the submucosa. B-ACBP also localized to the nucleus of squamous epithelial cells. PBR localization was indicated in tumour islands of invasive tissue sections. Quantitative RT-PCR also indicated that the expression levels of PBR were higher as compared to the ACBP genes expression in tumours. These results show that 1-ACBP, B-ACBP and PBR play a role in the pathogenesis of oesophageal tumours and also suggest the interaction between these genes with the immune system and that was also confirmed using bioinformatics analysis.

Citation Format: Zodwa Dlamini. Over-expression of 1-ACBP, B-ACBP and PBR genes in mast cells infiltrating oesophageal squamous cell tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3248.
Abstract 3316: The effects of dopamine receptor 2 on breast cancer tumor initiating cells
Authors: Tegowski Matthew , Santos Charlene , Baldwin Albert
Published: July 2016

Despite advances in early detection and treatment of breast cancers, metastatic disease remains a significant problem and a large cause of mortality in the US. Although tumors are characterized as a mass of uncontrolled cell division, it is thought that only small populations of cells, known as tumor initiating cells (TICs), are primarily responsible for metastasis. TICs are less differentiated than most tumor cells and many TICs show an epithelial-to-mesenchymal transition (EMT). Recently, the FDA-approved drug thioridazine, a dopamine receptor 2 (DRD2) antagonist, has been shown to inhibit pluripotency gene expression only in transformed stem cells. To test whether DRD2 can regulate TICs in breast cancer cells, two main assays were performed. The tumorsphere assay is used to measure TIC activity within a population of cells in vitro. In this assay, single cells are cultured in suspension, in the absence of serum. Cells must escape anoikis and grow without cell-cell contacts or the assortment of factors contained in serum. However, the gold standard in vivo assay to measure tumor initiation is the transplantation assay at limiting dilutions. Cells are injected into immunocompromised mice in decreasing numbers and the number of tumors each population of cells is capable of forming is measured. In this study the tumorsphere assay and transplantation assay both show that DRD2 supports TICs in breast cancers. Interestingly, our data suggest that DRD2 regulates TICs and cellular differentiation through the activity of the STAT3 transcription factor. Activation of STAT3 has been shown to induce gene expression changes that support TICs and upregulate the pluripotency factor OCT4. STAT3 activity can also induce EMT and resistance to some therapeutics. By inducing the expression of its own activator, IL-6, STAT3 can initiate a feed forward loop to maintain continual expression to promote TICs, EMT, and drug resistance. Halting the continual activation of STAT3 in these cells should be an important objective. Our data supports the concept that DRD2 may represent a new, and druggable target for therapies to decrease metastasis and/or recurrence by interfering with STAT3 and inhibiting TIC-like activities.

Citation Format: Matthew Tegowski, Charlene Santos, Albert Baldwin. The effects of dopamine receptor 2 on breast cancer tumor initiating cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3316.
Abstract 3322: Estrogen and nuclear respiratory factor 1 act as joint mediators of redox modulation and stem cell aging that contribute in the pathogenesis of breast cancer
Authors: Vazquez Juan , Roy Deodutta , Das Jayant
Published: July 2016

Deterioration of adult stem cell function with increasing age is a risk factor of breast cancer. Metastasis of breast cancer seems to be also influenced by aging or senescent cells overexpressing mitophagy/autophagy genes. Recently, estrogen, ROS, mitochondria and NRF1 activity have been implicated with stem cell aging, health and longevity. The exact underlying mechanisms of how aging of stem cells may increase the susceptibility to estrogen-induced carcinogenicity remain unknown. The main objective of this study was to examine whether estrogen, through activation of NRF1-mediated redox modulation and autophagic genes involved in senescence of stem cells, contributes in the development of breast cancer. To test this hypothesis, first we investigated the role of NRF1 to induce stemness by re-programming of breast epithelial cells (MCF-10A) and breast cancer cells (MCF-7 and MDA-MB231). We found that NRF1 promoted pluripotency markers: Oct4, Sox 2, and Nanog compare to MCF10A, MCF-7 or MDAMB 231 control cells. Loss of E-cadherin expression and gain of N-cadherin and vimentin expression in NRF1 overexpressing cells suggested that NRF1 promotes epithelial- mesenchymal transition. NRF1 promoted the ability to differentiate in vitro into a variety of cells (e.g chondrocytes, neurons, and smooth muscle cells). This suggested that NRF1 promotes multilineage differentiation potentials. Our data also showed that higher expression of NRF1 increased sizes of spheroids and ROS levels compared to controls. Mitophagy/Autophagy that regulates clearance of damaged mitochondria/apoptotic cells has important functions in regulating stem cell aging and tumorigenesis. Therefore, we examined the effect of estrogen on aging-associated diseases-related genes in NRF1 overexpressing as well as NRF1 silenced cells. Autophagy/Mitophagy/Apoptosis-related genes - BNIP3, PINK1, DJ-1 and LKB1 were altered in response to exposure of a carcinogenic concentration of estrogen. This effect of estrogen on these genes was further amplified by NRF1 overexpression and was inhibited by loss of NRF1. In summary, estrogen and NRF1 act as joint mediators of stem cell fate and reprogramming through a panel of critical stem cell proteins involved in modulating senescence and cell death. NRF1 seems to function as a rheostat to coordinate various cellular processes, such as resistance to apoptosis, autophagy and mitophagy of stem cells required for the stem cell aging as well as for the pathogenesis of breast cancer.

Citation Format: Juan Vazquez, Deodutta Roy, Jayant Das. Estrogen and nuclear respiratory factor 1 act as joint mediators of redox modulation and stem cell aging that contribute in the pathogenesis of breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3322.