bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2732: Cell-based reporter bioassays to evaluate the Fc gamma receptor-dependent agonistic activities for therapeutic antibodies targeting immune costimulatory receptors
Authors: Wang Jun , Beck Michael , Grailer Jamison , Stecha Pete , Hartnett Jim , Fan Frank , Cong Mei , Cheng Zhi-Jie Jey
Published: August 2018

Immune costimulatory receptors synergize with TCR-CD3 signaling to promote cell cycle progression, cytokine production, T cell survival and effector functions. They belong to immunoglobulin super-family (CD28, ICOS) and tumor necrosis factor receptor (TNFR) superfamily (4-1BB, OX40, CD27, CD40, GITR, DR3, and HVEM). Preclinical and clinical evidence shows that agonist antibodies against costimulatory receptors can stimulate antitumor immunity and are emerging as a promising approach for cancer immunotherapies. Furthermore, FcγR engagement, especially FcγRIIB due to its bioavailability, has been shown to provide a crosslinking scaffold for the antibody IgG to facilitate TNFR clustering/activation and become requisites for some agonist antibody activities. Here, we report the development of a suite of cell-based reporter bioassays to quantitatively measure the potencies of therapeutic antibodies designed to target costimulatory receptors. For this, we developed engineered effector cells that express each costimulatory receptor and a luciferase reporter driven by response element that specifically responds to costimulatory receptor signaling. We also developed a FcγR-expressing cell line to evaluate the involvement of FcγR in agonist antibody-mediated costimulatory signaling. The assays are specific for each costimulatory receptor, and can be used to detect both agonistic and blocking activities for the antibodies. When co-incubated with the engineered FcγR-expressing cells, they are able to show the Fcγ receptor-dependent or independent agonist activities. In summary, these reporter bioassays can serve as powerful tools in immunotherapy drug development for antibody screening and potency determination.

Citation Format: Jun Wang, Michael Beck, Jamison Grailer, Pete Stecha, Jim Hartnett, Frank Fan, Mei Cong, Zhi-Jie Jey Cheng. Cell-based reporter bioassays to evaluate the Fc gamma receptor-dependent agonistic activities for therapeutic antibodies targeting immune costimulatory receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2732.
Abstract 2734: Novel CTLA4 antibodies demonstrate potent antitumor activity in a humanized mouse model
Authors: Xiang Jie , Guo Yanan , Shen Yuelei , Yang Benny
Published: August 2018

CTLA4 (cytotoxic T-lymphocyte-associated protein 4), is a member of the immunoglobulin superfamily. It is expressed in T cells upon activation and transmits an inhibitor signal to T cells. Also, it is constitutively expressed in regulatory T cells (Tregs) which is associated with their immunosuppressive phenotype. CTLA4 is homologous to the co-stimulatory protein CD28, and both receptor binds to CD80 and CD86. Cancer cells can be recognized and destructed by the host's immune system. In this setting, CTLA4 functions as a brake to dampen anti-tumor T cell responses, which promote cancer progression. Antibodies targeting CTLA4 was expected to subvert T cell inhibition. Moreover, regulatory T cells residing in the tumor microenvironment can be killed by anti-CTLA4 antibody since these cells have higher expression level of CTLA4 comparing with the activated T cells. Yervoy, an anti-CTLA4 antibody, was the first FDA-approved antibody targeting the immune checkpointfamily, and it protects a fraction of cancer patients when either used alone or in combination with other drugs. We asked whether the efficacy of anti-CTLA4 antibodies could be evaluated in humanized mouse models. And if so, whether we can use in vivo assay to guide the development of potent antibodies targeting CTLA4. Here, we describe that using the platform established at Biocytogen, we successfully discovered two antibodies whose efficacy is equivalent or exceed that of Yervoy. The clinical evaluation of these new entities are wanted.

Citation Format: Jie Xiang, Yanan Guo, Yuelei Shen, Benny Yang. Novel CTLA4 antibodies demonstrate potent antitumor activity in a humanized mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2734.
Abstract 2759: Rational combinations for immune checkpoint blockade using β-catenin RNAi therapy
Authors: Ganesh Shanthi , Shui Serena , Craig Kevin , Wang Weimin , Brown Bob D. , Abrams Marc
Published: August 2018

Recent research has shown that Wnt/β-catenin signaling drives resistance to cancer immunotherapy by promoting the exclusion of T-cells from the tumor microenvironment. DCR-BCAT is an RNAi-based experimental medicine targeting β-catenin, formulated in a tumor-selective nanoparticle. We had previously reported that systemic administration of DCR-BCAT increased tumor-associated cytotoxic T-cells and dramatically improved responses to immunotherapy agents, in murine syngeneic models and GEM models. In this new work, we explore the mechanisms by which Wnt/β-catenin signaling promotes resistance to immune checkpoint blockade, and propose context-specific therapeutic combinations using RNAi therapy. We will present novel in vivo experimentation demonstrating that DCR-BCAT significantly enhances sensitivity to immunotherapy using different drug regimens in multiple tumor types.

Citation Format: Shanthi Ganesh, Serena Shui, Kevin Craig, Weimin Wang, Bob D. Brown, Marc Abrams. Rational combinations for immune checkpoint blockade using β-catenin RNAi therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2759.
Abstract 2762: Identification of novel immunotherapeutic targets in anaplastic thyroid cancer
Authors: Chakraborty Sanjukta , Maniyar Rachana R. , Tuli Neha Y. , Rahoma Ghada Ben , Singh Sarnath , Kamat Ameet , Berzofsky Craig , Budenz Cameron , Moscatello Augustine , Geliebter Jan , Tiwari Raj K.
Published: August 2018

Thyroid cancer is the most rapidly increasing cancer in the US with anaplastic thyroid cancer (ATC) being the rarest and most aggressive form. ATC patients display a higher mutational burden and are refractory to current mainstream treatments including second generation kinase inhibitors like vemurafenib (PLX4032). BRAFV600E is one of the most common mutations associated with this phenotype. Presence of BRAFV600E has been associated with an immunosuppressive microenvironment in thyroid cancer that presumably facilitates immune evasion. With recent advancements in immunotherapy, well defined targeted treatment plans can address the unmet medical need of ATC. In an effort to define potential immunotherapeutic targets that can be combined with small molecule inhibitors in this subtype, we evaluated the expression of immune checkpoint molecules in four thyroid cancer cell lines TPC-1 (papillary), BCPAP (BRAFV600E positive papillary), 8505C (BRAFV600E positive anaplastic) and CGTH-W-1 (follicular) by qRT PCR at the basal level and after treatment with vemurafenib and mTORC1 inhibitor rapamycin. Prominent co-stimulatory molecules like CD27, CD30, 4-1BB and DR3 were significantly downregulated at the transcript level in ATC (8505C) as compared to the other thyroid cancer subtypes. We observed a higher baseline expression of co-inhibitory molecules like full length CTLA4 (mCTLA4), soluble CTLA4 (sCTLA4), LAG3, 2B4, PD-1 and PD-L1 in ATC (8505C) compared to the other subtypes of thyroid cancer. Although vemurafenib treatment decreased the expression of PD-L1 as expected, interestingly, it enhanced the expression of co-inhibitory molecules LAIR1, 2B4, mCTLA4 and PD-1 by approximately 1.5 folds. These results suggest an inherent redundancy in inhibitory immune checkpoint molecules that presumably compensate for each other, functionally, making them novel targets in ATC. With our study we identified a distinct group of co-inhibitory molecules in ATC that can be targeted by antagonistic antibodies in a combinatorial treatment regimen with small molecule inhibitors like vemurafenib.

Citation Format: Sanjukta Chakraborty, Rachana R. Maniyar, Neha Y. Tuli, Ghada Ben Rahoma, Sarnath Singh, Ameet Kamat, Craig Berzofsky, Cameron Budenz, Augustine Moscatello, Jan Geliebter, Raj K. Tiwari. Identification of novel immunotherapeutic targets in anaplastic thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2762.
Abstract 2768: Potentiating the action of antibody-dependent cell-mediated cytotoxicity with immunocytokines
Authors: Murer Patrizia , Kiefer Jonathan D. , Plüss Louis , Neri Dario
Published: August 2018

Intact antibodies in the IgG format typically display only moderate in vivo activity against solid tumor masses, when their mechanism of action relies on antibody-dependent cellular cytotoxicity (ADCC). The therapeutic activity is mainly limited by the lack of immune effector cells (and most notably NK cells) in the neoplastic mass.

Our group had previously reported that the therapeutic activity of Rituximab and other intact immunoglobulins could be strongly potentiated by the antibody-based targeted delivery of interleukin-2 (IL2) to the tumor environment. The combination regimen induced complete remissions of established localized lymphomas and provided long-lasting protection from disseminated lymphoma, in mouse models that featured functional NK cells.

In this study, we examined the ADCC activity of TA99, a monoclonal antibody which specifically recognizes gp75, a conserved tumor-associated antigen over-expressed in both murine and human melanoma cells. In a preventive setting TA99 in murine IgG2a format completely inhibited the formation of lung metastases in mice, which had been injected intravenously with B16F10 melanoma cells. However, when the B16F10 melanoma tumor was grown subcutaneously in immunocompetent mice, the ADCC activity was not potent enough to eradicate the pre-established tumors and only a modest tumor growth inhibition was observed. A microscopic tissue distribution analysis revealed that TA99-IgG2a had selectively accumulated in the tumor mass compared to normal organs and that NK cells within the neoplastic lesions were scarce.

In order to increase NK cell density at the tumor site and potentiate ADCC activity, we developed fusion proteins of the TA99 antibody with murine TNFα, IL2 and IL12. The antibody-cytokine fusion proteins were used alone and in combination with TA99-IgG2a. Combination treatment led to a marked increase of anti-cancer activity against established subcutaneous tumors. Our findings indicate that the targeted delivery of certain pro-inflammatory cytokines to the tumor site potentiates the anti-cancer properties of intact antibodies, enhancing their ability to induce ADCC.

Citation Format: Patrizia Murer, Jonathan D. Kiefer, Louis Plüss, Dario Neri. Potentiating the action of antibody-dependent cell-mediated cytotoxicity with immunocytokines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2768.
Abstract 2805: Combretastatins as highly cytotoxic natural compounds
Authors: Dzubak Petr , Rehulka Jiři , Gurska Sona , Riener Uwe , Hajduch Marian
Published: August 2018

Combretastatins originally isolated from the South African willow tree Combretum cafrum are highly cytotoxic natural products, but their use is limited because of the cis/trans isomerization of the cis-stilbene moiety under physiological conditions. Herein we report the preparation of cis-restrained carbocyclic analogs of CA-4. The compounds, which differ by the size and hybridization of the carbocyclic ring have been evaluated for cytotoxic activity in vitro against a panel of human cancer and two non-tumor fibroblast cell lines and for their ability to inhibit tubulin polymerization. Biological data, supported by molecular docking studies, identified a cyclobutenyl derivative of the natural product as a promising drug candidate with selective nanomolar cytotoxic activity towards cancer cell lines, showing high potency against multidrug-resistant cells and inhibiting tubulin polymerization. This work was supported by Ministry of Health of the Czech Republic (15-31984A), internal grant of Palacky University (IGA_LF_2017_026) and by the Czech Ministry of Education, Youth and Sports LO1304, CZ-OPENSCREEN, (LM2015063) and EATRIS (LM2015064).

Citation Format: Petr Dzubak, Jiři Rehulka, Sona Gurska, Uwe Riener, Marian Hajduch. Combretastatins as highly cytotoxic natural compounds [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2805.
Abstract 2817: RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer
Authors: Mani Chinnadurai , Clark David , Somasagara Ranganatha , Spencer Sebastian , Tripathi Kaushlendra , Palle Komariah
Published: August 2018

Ovarian cancer (OC) is deadly and incurable for patients who relapse after primary cancer is treated with surgery and platinum-based chemotherapy. Unfortunately, OC has a high rate of disease recurrence (70-80%) and most recurrent tumors are chemoresistant, causing deaths of nearly 15,000 women from this disease each year in U.S.A., which highlights the need for new therapeutic strategies. Platinum drug resistance and refractory disease pose major challenges in treating this disease and are major factors contributing to the poor survival rate of OC patients. Our studies demonstrated that RAD6 (an E2 ubiquitin conjugating enzyme) signaling is stimulated upon chemotherapeutic treatment and promotes expression of DNA repair proteins including Fanconi anemia (FA) pathway. Analysis of clinical samples revealed upregulation of RAD6 in ovarian tumors compared to normal ovarian tissues and RAD6 inhibition reduces cancer cell survival. In a pilot clinical study (n=26) comparing matched OC tumors from patients before and after carboplatin chemotherapy regimen, we found that RAD6 was upregulated after treatment and correlated with both chemoresistance and poor progression-free survival. Knockdown or inhibition of catalytic activity (small-molecule inhibitor) of RAD6 attenuated carboplatin-induced monoubiquitination of target proteins such as FANCD2, PCNA and histone 2B, thereby sensitizing OC cells to carboplatin. Interestingly, inhibition of RAD6 alone in OC cells induced replication stress and reduced cell survival and proliferation by arresting cells in the G2/M phase. Moreover, RAD6 plays an important role in the activation of the trans-lesion synthesis (TLS) pathway by monoubiquitinating PCNA and in the activation of the FA DNA repair pathway. These are critical mechanisms for cells to repair DNA crosslinks induced by platinum drugs. Together with these observations, our data suggest that inhibition of RAD6 could be a viable therapeutic target for overcoming platinum resistance and disease recurrence induced by FA pathway in ovarian cancer.

Citation Format: Chinnadurai Mani, David Clark, Ranganatha Somasagara, Sebastian Spencer, Kaushlendra Tripathi, Komariah Palle. RAD6 promotes acquired chemoresistance and a poor prognostic marker in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2817.
Abstract 2821: Tousled like Kinase 1 binds to and regulates the protein kinase Nek1: Its implication in prostate cancer
Authors: Singh Vibha , Jaiswal Praveen K. , Koul Hari K. , Yu Xiuping , Benedetti Arrigo
Published: August 2018

Introduction: Prostate Cancer (PCa) is one of the most common urological malignancies in men in the United States. Tousled Like kinases (TLKs) are involved in numerous cellular functions, including the DNA Damage Response (DDR). Through a novel proteomic approach, we have identified that NIMA kinase NEK1 strongly interacts and co-localizes with TLKs and has a role in the DDR, upstream of ATR and Chk1. In the present study we have tested Thioridazine (THD), an anti-psychotic drug and inhibitor of TLKs in inhibiting the activity of NEK1 in prostate cancer cell lines and LNCaP cell derived xenografts in NOD/SCID mice and the subsequent role of ATR-Chk1 axis following DNA damage.

Material & Methods: We have used a prostate cancer cell line viz. LNCaP, C4-2, C4-2b, 22Rv1, DU145 and PC3 and normal prostate cell line RWPE-1. Clonogenic activity was measured by colony formation assay. Immunoblotting was done for TLKs, NEK1, p-ATR and p-Chk1 protein in PCa cell line and tumor xenografts tissues. LNCaP xenografts in NOD/SCID mice were used in present study. We have used THD (alone) or in combination with the anti-androgen drug bicalutamide in PCa cell lines as well as in xenografts mice model.

Results: Treatment with THD suppresses the outgrowth of androgen-independent (AI) colonies of LNCaP cells cultured with bicalutamide. Moreover, THD significantly inhibited the colony formation efficiency of several PCa cells in vitro (even of androgen independent lines). Intra-Peritoneal (I.P.) administration of THD or Bicalutamide long-term was not very effective in inhibiting tumor growth. In contrast, combination therapy of THD and Bicalutamide remarkably inhibited the tumor growth in LNCaP xenografts model. Further p-ATR and p-Chk1 axis was inhibited by treatment with THD and in combination with bicalutamide as evident by immunoblotting of residual tumors. In cells, following DNA damage, addition of the TLK inhibitor THD impaired ATR and Chk1 activation, indicating the existence of a TLK1>NEK1>ATR>Chk1 pathway.

Conclusions: Our data indicated that THD repressed growth of PCa cells in vitro and in vivo, and for Androgen-dependent (LNCaP) cells, in combination with bicalutamide it was very effective at preventing outgrowth of AI cells and hence as a targeted ADT adjuvant therapy. Moreover, THD impaired DDR. Collectively, these results strongly suggest that THD might be a novel anti-tumor agent for use in prostate cancer.

Citation Format: Vibha Singh, Praveen K. Jaiswal, Hari K. Koul, Xiuping Yu, Arrigo Benedetti. Tousled like Kinase 1 binds to and regulates the protein kinase Nek1: Its implication in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2821.
Abstract 2833: Single-cell imaging reveals MAPK pathway reactivation in drug-tolerant melanoma cells
Authors: Yang Chen , Tian Chengzhe , Spencer Sabrina L.
Published: August 2018

Spontaneous genetic mutations allow an initially drug-sensitive population of cancer cells to acquire a drug-resistant phenotype. However, little is known about how drug-sensitive cells first evade drug action and survive in the presence of drug, referred to as "drug tolerance," a crucial step on the road to resistance. In this study, we combined single-cell time-lapse microscopy and MATLAB-based automated cell tracking to identify the molecular basis of drug tolerance. By simultaneously monitoring CDK2 and ERK activity in single cells, we found that melanoma cells harboring a BRAF-V600E mutation have high ERK activity and consecutively cycled with an inter-mitotic time of around 14 hr in full growth media. Upon treatment with dabrafenib, an ATP competitive B-Raf inhibitor, all cells entered a CDK2-low quiescence with reduced ERK activity. Strikingly, after 72 hr of dabrafenib treatment, a fraction of cells escaped drug action, re-entered the cell cycle, and divided once in presence of drug before re-entering a transient quiescence. Additional cells continued to escape and divide in the presence of drug, with a steady-state level of about 10% of the population engaged in the cell cycle at any point during the week-long observation period. We refer to cells that re-entered the cell cycle as "escapees" and cells that stayed in quiescence during the observation period as "non-escapees." Remarkably, we found that escapees showed significantly higher ERK activity than non-escapees after a few days of treatment, even though their initial ERK activities were indistinguishable. To test whether reactivation of the MAPK pathway is the cause of cell cycle re-entry, we co-treated cells with dabrafenib and the MEK inhibitor trametinib. This co-treatment resulted in even lower ERK activity and elimination of the escapee population. This result implies that dabrafenib, even at high doses, does not fully turn off the MAPK pathway, thereby enabling eventual escape from drug. By monitoring escaping cells at the molecular level in real time, our work thus suggests a possible mechanism for cells to develop drug tolerance in less than three days, long before acquiring genetic mutations.

Citation Format: Chen Yang, Chengzhe Tian, Sabrina L. Spencer. Single-cell imaging reveals MAPK pathway reactivation in drug-tolerant melanoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2833.
Abstract 2843: Calcium blockers modulate the steroid resistance in acute lymphoblastic leukemia
Authors: Jung Hyun Joo
Published: August 2018

Background: Acute lymphoblastic leukemia (ALL) is one of common cancers in children and adults, and a fair number of ALL patients still die although the overall survival rate is approaching 90% with risk-directed therapy in many developed countries. Response to steroid is the most important prognostic factor of patients with ALL, and the development of steroid resistance is lethal to the ALL patients. To improve survival for steroid-resistant ALL patients, it is necessary to develop new concepts to overcome the steroid resistance of ALL.

Methods: We generated the steroid-adapted subclones through prolonged cultures of ALL cell lines with gradually increased steroid concentration.Also, we used biochemical and molecular methodologies to demonstrate the signaling axis of tissue transglutaminase (TG2)-nuclear factor-kappa B (NF-kappa B) and cell cycle to evaluate the effect of calcium blockers on the steroid-resistant ALL cells.

Results: Steroid-adapted ALL cells that were generated by culture with gradually increased steroid concentration were much more resistant to steroid than their parent ALL cells. We found that calcium blockers altered TG2 activity and nuclear factor-kappa B (NF-kappa B) expression in these steroid-resistant ALL cells. Also, calcium blockers induced the change of expression of NF-kappa B target genes in steroid-adapted ALL cells. In addition, calcium blockers induced the change of ABC transporter expression and the quiescence of steroid-resistant ALL cells. We also found that calcium blockers induced apoptosis of steroid-resistant ALL cells and reduced the steroid resistance of steroid-resistant ALL cells.

Conclusion: This study shows that calcium blockers improved the cytotoxicity of steroid on steroid-resistant ALL cells via manipulation of TG2 and NF-kappa B activities and cell cycle. The combination of calcium blockers with chemotherapeutic agents may be a new alternative strategy to overcome the steroid resistance of ALL.

Citation Format: Hyun Joo Jung. Calcium blockers modulate the steroid resistance in acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2843.
Abstract 2866: Anticancer effect of a new cyclic peptide ALOS4 is associated with its systemic anti-inflammatory activity
Authors: Nesher Elimelech , Pinhasov Albert , Becker Maria , Kirby Michael , Harazi Raichel Cohen , Yakobovich Shiri , Agranyoni Oryan , Shoval Bar , Elbaz Shany I. , Udartseva Olga , Gitlin Ilya , Leonova Katerina , Gurova Katerina , Gudkov Andrei , Koman Igor
Published: August 2018

The association of chronic inflammation with cancer development and progression has been well recognized. Here, we report a synthetic cyclic peptide, ALOS4, capable of suppressing tumor growth following systemic administration and possessing anti-inflammatory properties. Although ALOS4 was initially isolated by phage display for its ability to bind avb3 integrin and demonstrated tumor-suppressor activity in preclinical xenograft and syngeneic models of melanoma, it surprisingly showed no functional activity resembling RGD peptides in functional in vitro assays. Remarkably, ALOS4 displayed no signs of toxicity in treated animals, even at doses exceeding >100-fold beyond the efficacious dose. To identify the mechanisms underlying profound antitumor activity of this safe peptide, we used a large panel of cell-based repeater assays designed to detect modulators of a variety of signaling pathways including p53, NF-kB, and different types of stress responses including heat shock and hypoxia. We also tested the effects of ALOS4 on tumor cell growth, adhesion, clonogenicity, morphology and other in vitro properties. ALOS4 showed no detectable activity in any of these numerous assays with one exception: it suppressed the ability of treated cells to induce interferon type I signaling in response to mimics of double-stranded RNA (Poly I:C). Based on this observation, we hypothesized that the antitumor effect of ALOS4 is driven by a systemic anti-inflammatory effect rather than by a direct effect on tumor cells. Consistently, ALOS4 treatment dramatically altered both the abundance and content of the immunocyte population infiltrating subcutaneous melanomas in mice. These results suggest that ALOS4 may be an anticancer agent with a new mechanism of action that targets the tumor-supporting interferon-driven mechanism of tumor-host interaction.

Citation Format: Elimelech Nesher, Albert Pinhasov, Maria Becker, Michael Kirby, Raichel Cohen Harazi, Shiri Yakobovich, Oryan Agranyoni, Bar Shoval, Shany I. Elbaz, Olga Udartseva, Ilya Gitlin, Katerina Leonova, Katerina Gurova, Andrei Gudkov, Igor Koman. Anticancer effect of a new cyclic peptide ALOS4 is associated with its systemic anti-inflammatory activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2866.
Abstract 2869: Nintedanib abrogates the activation and tumor-promoting effects of fibroblasts from lung adenocarcinoma patients
Authors: Alcaraz Jordi , Gabasa Marta , Ikemori Rafael , Hilberg Frank , Reguart Noemí
Published: August 2018

Nintedanib is a clinically-approved multikinase receptor inhibitor that, in combination with docetaxel, provides clinical benefits to advanced lung adenocarcinoma (ADC) patients but not to lung squamous cell carcinoma (SCC) patients. However, the mechanisms underlying the selective therapeutic effects of Nintedanib in ADC remain poorly understood. Of note, Nintedanib is also approved to treat patients with idiopathic pulmonary fibrosis (IPF), a rare disease characterised by an abundant desmoplastic stroma rich in pathologically activated fibroblasts. Since the tumor stroma in lung cancer is also desmoplastic, and we recently showed that tumor-associated fibroblasts (TAFs) derived from ADC and SCC patients exhibit different phenotypes in vitro, we hypothesized that TAFs may underlie the selective effects of Nintedanib in ADC. To test this hypothesis we activated TAFs in culture with the pro-fibrotic cytokine TGF-β1 in the presence of increasing concentrations of Nintedanib, and collected the corresponding conditioned medium. Remarkably SCC-TAFs showed very modest inhibition of a panel of fibrotic markers including α-SMA, P4HA2 and fibrillar collagens (COL1A1, COL3A) in response to Nintedanib, in striking contrast to ADC-TAFs and paired lung parenchyma fibroblasts, which were markedly affected. This was matched by a significant reduction in the abilities of the conditioned medium of ADC-TAFs but not SCC-TAFs to promote cancer cell growth and invasion in a panel of lung cancer cell lines after Nintedanib treatment. These results reveal that Nintedanib is an effective inhibitor of stromal fibrosis and its associated tumor-promoting effects in ADC, and that the poor antifibrotic response of SCC-TAFs to Nintedanib may contribute to the differential clinical benefit observed in both subtypes. Our findings also support that TGF-β signalling and aberrant TAF-carcinoma cross-talk are regulated by different mechanisms in ADC and SCC. In addition they support that preclinical models based on carcinoma-TAF interactions may help defining the mechanisms of the poor antifibrotic response of SCC-TAFs to Nintedanib and testing new combined therapies to further expand the therapeutic effects of this drug in solid tumors.

Citation Format: Jordi Alcaraz, Marta Gabasa, Rafael Ikemori, Frank Hilberg, Noemí Reguart. Nintedanib abrogates the activation and tumor-promoting effects of fibroblasts from lung adenocarcinoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2869.
Abstract 2892: EGLN1 is a synthetic lethal target in ARID1A-mutant ovarian cancer
Authors: Briggs Kimberly J. , Min Chengyin , Zhang Hongxiang , Huang Alan
Published: August 2018

The successful use of PARP inhibitors for the treatment of BRCA-mutant ovarian cancer underscores the importance of synthetic lethality as a therapeutic opportunity for tumors with loss-of-function mutations in tumor suppressor genes. Ovarian cancer ranks as the fifth deadliest cancer among women, and one ovarian cancer subtype, clear cell carcinoma, is particularly underserved. The most frequent genetic alteration in ovarian clear-cell carcinoma is loss-of-function mutation of the SWI/SNF-A complex subunit, ARID1A. We interrogated the data published by Project Achilles to determine candidate synthetic lethal partners with ARID1A in ovarian cancer, and identified EGLN1, a member of the EglN-family of prolyl hydroxylases. Inhibition of EGLN1, either genetically or pharmacologically, leads to decreased viability in ovarian cancer cell lines. Pharmacological inhibition of EGLN1 is clinically achievable as evidenced by several well-tolerated, small molecule inhibitors currently in clinical trials for the treatment of anemia in the context of chronic kidney disease. The synthetic lethal interaction of ARID1A and EGLN1 may provide a therapeutic opportunity for patients diagnosed with ovarian clear-cell carcinoma.

Citation Format: Kimberly J. Briggs, Chengyin Min, Hongxiang Zhang, Alan Huang. EGLN1 is a synthetic lethal target in ARID1A-mutant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2892.
Abstract 2905: Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells
Authors: Saad Rama , Munirathinam Gnanasekar , Kucynda Theresa , Ribeiro Marta , Lindholm Paul , Balla Andre
Published: August 2018

While cadmium is a well-known lung carcinogen, its role in prostate cancer is yet to be understood. Recently, a meta-analysis study showed that cadmium did not increase the risk of prostate cancer. It is not known whether cadmium exposure at environmentally relevant concentrations increases aggressiveness of already existing prostate cancer. Although our lab previously showed that the 75th percentile of cadmium concentration in prostate cancer was associated with biochemical recurrence, more evidence is needed to substantiate this finding. We also showed evidence that cadmium promotes prostate cancer cells migration and invasion via inducing the expression of translationally controlled tumor protein (TCTP). Furthermore, it was demonstrated that cadmium induces the phosphorylation of p38, and that the p38 inhibitor SB203580 (SB) blocks the effects of cadmium on migration and invasion. In this study, we aimed to delineate the signaling events upon cadmium treatment; whether p38 or TCTP is upstream. We addressed this via inhibition of p38 using SB203580 and by inducing TCTP degradation via dihydroartemisinin (DHA) followed by measurement of TCTP expression and phosphorylation of p38 respectively. p38 inhibition led to the increased expression of TCTP on both mRNA and protein levels. Pretreatment with DHA led to less TCTP expression and less phosphorylation of p38. We also aimed to understand the effect of cadmium on cell proliferation, survival and migration. While DHA lowered the colony count and EdU incorporation, cadmium did not alter these functions. In addition, DHA abrogated the cadmium-mediated migration of PC3-Inv prostate cancer cell line. Furthermore, we aimed to determine the effect of nanomolar cadmium concentrations on the phosphorylation of PlK1, which is well established to be upstream of TCTP. Our results demonstrated that nanomolar concentrations of cadmium resulted in increased phosphorylation of PlK1 in both PC3 and LNCaP cells. Altogether, our results suggest that environmentally relevant exposures of cadmium induce TCTP expression through several pathways, and that there is a feedback mechanism between p38 and TCTP.

Citation Format: Rama Saad, Gnanasekar Munirathinam, Theresa Kucynda, Marta Ribeiro, Paul Lindholm, Andre Balla. Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2905.
Abstract 2922: The utility of BET inhibition in the sensitization and re-sensitization of pancreatic cancer cells to paclitaxel
Authors: Hamdan Feda H. , Kutschat Ana P. , Sen Madhobi , Wang Xin , Johnsen Steven A.
Published: August 2018

While the mortality rates of cancer are generally declining, pancreatic cancer persists to be an exception with a 5-year-survival rate of less than 7%. As late diagnosis and resistance to conventional therapies are major contributors to high mortality rates, novel treatment options are needed to improve the prognosis of pancreatic cancer patients. Recent findings showed that inhibition of the Bromodomain and Extraterminal Domain (BET) family of epigenetic reader proteins is effective, both alone and in combination with conventional chemotherapy, in decreasing pancreatic tumor growth in patient-derived xenografts. Thus, we aim to evaluate the potential role of and mechanisms of action of BET inhibitors (BETi) as an adjuvant therapy option in pancreatic ductal adenocarcinoma. We established L3.6 pancreatic cells that are resistant to paclitaxel by maintaining them in incrementally higher concentrations for 3 months. Paclitaxel-resistant cells showed a half maximal inhibitory concentration (IC50) 100-fold higher than that of parental cells. Intriguingly, we report that low, non-cytostatic concentrations of the BETi, JQ1, not only sensitized cells to paclitaxel, but also induced significant re-sensitization of chemoresistant cells. In order to elucidate the mechanism by which BETi induces chemo-sensitization, we investigated the differential gene expression profiles of resistant and sensitive cells. Thereby, we uncovered that BETi reverses the regulation of transcriptionally-activated genes in resistant cells. Interestingly, these genes showed a major tendency to gain BRD4 at putative enhancer regions. We anticipate that enhancer RNAs (eRNAs) transcribed at these particular enhancers may provide us with novel biomarkers which can be used to predict chemotherapeutic resistance and the possibility of re-sensitization by BETi. In conclusion, we provide evidence that BETi can potentially be used as adjuvant agents in pancreatic cancer. However, approaches may likely be largely independent of their anti-proliferative effects that require higher concentrations and possibly lead to intolerable adverse effects, but rather to their transcriptional regulatory functions that attenuate the activated programs in chemoresistant cancers.

Citation Format: Feda H. Hamdan, Ana P. Kutschat, Madhobi Sen, Xin Wang, Steven A. Johnsen. The utility of BET inhibition in the sensitization and re-sensitization of pancreatic cancer cells to paclitaxel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2922.
Abstract 2939: ETC159, a porcupine inhibitor, exhibits synergism with PI3K inhibitors in 3-dimensional cell culture
Authors: Sepramaniam Sugunavathi , Chew Xin Hui , Ngeow Kao Chin , Lee May Ann
Published: August 2018

Aberrations in WNT signaling, a pathway regulated by a family of secreted glycoproteins known as WNTs, is implicated as a cause for cancer. Post-translational modification of WNTs by porcupine is critical for their activity and eventual activation of the WNT pathway. ETC-159 is an orally available, potent porcupine inhibitor. Addition of ETC-159 suppresses cancer proliferation in several cell lines by blocking the secretion and activity of all WNTs. Nevertheless, tumor growth is driven by complex molecular interactions that dysregulate several pathways at any one time. Thus, early drug discovery studies have increasingly evolved to target multiple molecules or pathways. As therapeutic approaches using combinations of drugs directed at multiple targets can improve treatment response, in this study we explored the possibility of identifying compounds that are synergistic with ETC-159. Unlike conventional two-dimensional combination drug screening, we used the three-dimensional soft agar colony formation assays for the study. Dose-response curves were first independently established to obtain the EC50 ranges for each drug, before proceeding to combination treatments. Using the Chou-Talalay Drug Combination Software, CompuSyn, we identified several inhibitors, which target the PI3K pathway, to act synergistically with ETC-159 in pancreatic cell lines HPAF-II, ASPC-1 and CFPAC-I. Similar treatments in nonpancreatic cell lines indicated that the observed synergism was not cell-line specific, hence highlighting the applicability of such combination treatments for different cancers.

Citation Format: Sugunavathi Sepramaniam, Xin Hui Chew, Kao Chin Ngeow, May Ann Lee. ETC159, a porcupine inhibitor, exhibits synergism with PI3K inhibitors in 3-dimensional cell culture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2939.
Abstract 2945: Arsenic trioxide sensitizes glioma stem cells to brain penetrant PI3K and mTOR inhibitor GDC-0084
Authors: Dong Jianwen , Martinez-Ledesma Emmanuel , Nguyen Nghi , Carrillo Caroline , Piao Yuji , Henry Verlene , Park Soon Young , Tiao Ningyi , Stephan Clifford , Verhaak Roel , Sulman Erik , Balasubramaniyan Veerakumar , Groot John F. de
Published: August 2018

Glioblastoma is the most aggressive primary malignant brain tumor with few effective therapies. The current study evaluated arsenic trioxide (As2O3, ATO), a small-molecular agent that inhibits tumor growth via promoting promyelocytic leukemia protein (PML) degradation, in combination with multiple PI3K/mTOR inhibitors using high-throughput screening (HTS) to validate if ATO reverses glioblastoma resistance to PI3K/mTOR-targeted therapy. Quantitative single-agent and 2-drug combinations (5 drug doses, maximal concentration of 1 uM of each agent) were evaluated in 20 patient-derived glioma stem-like cells (GSCs). ATO was applied as an “anchor” drug and several mTOR and EGFR inhibitors as “probe” drugs to explore potential combination efficacy. Data from single-agent screening demonstrated that brain penetrant PI3K/mTOR inhibitor GDC-0084 potently inhibited cell viability with an IC50 ranging from 0.12μM to 5.78μM under normoxic conditions. Under hypoxic conditions, 10 of the 16 GSC cell lines remained sensitive, indicating less efficacy of GDC-0084 in the setting of a hypoxic microenvironment. Evaluation of drug combinations identified ATO and GDC-0084 as the most effective combination in vitro. ATO was synergistic with GDC-0084 in several GSCs resistant to GDC-0084 monotherapy. GSC sensitivity to GDC-0084 as single agent and in combination correlated with apoptosis, angiogenesis and PI3K/Akt pathways using gene set enrichment analyses (GSEA). In vitro combination treatment significantly inhibited PML, p-S6, p-AKT and p-mTOR expressions compared to single agent. In an orthotopic mouse model of glioma, targeting PI3K/mTOR with GDC-0084 prolonged the median survival to 81 days compared to 69 days in the control group. The efficacy of combining ATO and GDC-0084 in an orthotopic GSC mouse model is ongoing. Our studies confirm prior work demonstrating the efficacy of combining GDC-0084 with ATO, which now requires clinical validation.

Citation Format: Jianwen Dong, Emmanuel Martinez-Ledesma, Nghi Nguyen, Caroline Carrillo, Yuji Piao, Verlene Henry, Soon Young Park, Ningyi Tiao, Clifford Stephan, Roel Verhaak, Erik Sulman, Veerakumar Balasubramaniyan, John F. de Groot. Arsenic trioxide sensitizes glioma stem cells to brain penetrant PI3K and mTOR inhibitor GDC-0084 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2945.
Abstract 2948: Synergistic effect of combining Akt inhibitor SC66 with anticancer drugs cisplatin and paclitaxel in chemoresistant ovarian cancer cells
Authors: Wu Yi-Hui , Chou Cheng-Yang
Published: August 2018

Background and aims Akt plays a central role in regulating cell growth and cell cycle progression and is regarded as a promising therapeutic target. We examined whether Akt inhibition by SC66 is therapeutically efficacious in the treatment of ovarian cancer as a single agent and in combination with chemotherapy drugs.

Methods Using eight human ovarian cancer cell lines, we determined the effect of SC66 by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, western blot, and apoptosis assays. We evaluated the association between phospho-Akt/mTOR, COL11A1 and SC66 sensitivity. We also determined the effect of SC66 on tumor growth using mice inoculated with human ovarian cancer cells.

Results Cell sensitivity to SC66 was inversely correlated with the expressions of phosphorylation of Akt and COL11A1, and cisplatin resistance. SC66 inhibited the phosphorylation of downstream 4E-BP1 and p70S6 kinase. SC66 also attenuated the expression of TWIST1 and Mcl-1, important factors in invasiveness and anti-apoptosis. SC66 sensitizes chemo-resistant cells to cisplatin and paclitaxel treatment, and enhanced apoptosis in the chemo-resistant cells. In addition, SC66 inhibited COL11A1 expression via decreasing the binding activity of c/EBPβ and NF-YA to the COL11A1 promoter, which was associated with chemoresistance and cell invasiveness respectively. In vivo, treatment with SC66 enhanced the therapeutic efficacy of cisplatin and paclitaxel in mouse xenograft.

Conclusions These results indicate the SC66 could have therapeutic efficacy in human ovarian cancers.

Citation Format: Yi-Hui Wu, Cheng-Yang Chou. Synergistic effect of combining Akt inhibitor SC66 with anticancer drugs cisplatin and paclitaxel in chemoresistant ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2948.
Abstract 2988: Loss of Rbm38 cooperates with mutant p53 to promote lymphomagenesis through downregulation of Pten
Authors: Zhang Jin , yang Heejung , Zhang Yanhong , Chen Mingyi , Chen Xinbin
Published: August 2018

The tumor suppressor TP53 is the most commonly mutated gene in human cancers and mutant p53 has a gain of function by promoting tumor progression, metastasis, and resistance to anticancer therapy. Interestingly, the RNA binding protein Rbm38, a critical regulator of mutant p53 translation, is frequently lost in tumors with mutant p53. To determine the role of the Rbm38-mutant p53 axis in tumorigenesis, we showed that loss of Rbm38 significantly alters the cancer susceptibility of mutant p53 knockin mice by shortening the lifespan, altering the tumor incidence, and promoting T-cell lymphomagenesis. To understand how Rbm38 deficiency promotes mutant p53 gain of function, we showed that loss of Rbm38 not only enhances mutant p53 expression but also decreases expression of tumor suppressor Pten, a critical regulator of T-cell development. Furthermore, we showed that Rbm38 is required for Pten expression by stabilizing Pten mRNA through an AU-rich element in its 3'UTR. Thus, we have uncovered a novel mechanism by which Pten is regulated by Rbm38 via mRNA stability. Our data also suggest that Rbm38 controls T-cell lymphomagenesis by concomitantly modulating mutant p53 and Pten, which may be explored as a therapeutic strategy for the treatment of T-cell malignancies.

Citation Format: Jin Zhang, Heejung yang, Yanhong Zhang, Mingyi Chen, Xinbin Chen. Loss of Rbm38 cooperates with mutant p53 to promote lymphomagenesis through downregulation of Pten [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2988.