bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3500: Combinations of ARQ087 with chemotherapeutic agents are safe and show a striking antitumor activity in different xenograft models
Authors: Chilà Rosaria , Guffanti Federica , Hall Terence , Ricci Francesca , Broggini Massimo , Damia Giovanna
Published: August 2015

ARQ087 is a non ATP-competitive tyrosine kinase inhibitor with activity against the FGFR receptor family, and currently in Phase I clinical studies for the treatment of advanced solid tumors. It potently inhibits FGFR1, 2, and 3, as well as mutant FGFR2 (N549H) and FGFR3 (K650E/M) with IC50 values in the low nanomolar range in biochemical assays. ARQ 087 has shown potent anti-proliferative activity in a panel of cancer cells with deregulated FGFR1 and FGFR2 pathways and exerted a dose-dependent antitumor activity in in vivo systems with FGFR1/FGFR2-driven xenografts model (H1581 and SNU-16 respectively) and models harboring FGFR2-activating mutation (AN3CA and MFE296). Given orally in a 15 daily administration, ARQ 087 has shown a very safe profile while inducing tumor regressions in FGFR driven models. The feasibility of combining ARQ087 with chemotherapy was investigated in H1581 FGFR1-amplified lung xenograft and in SNU16-FGFR2 driven gastric xenografts. Tumor bearing mice, were randomized to receive vehicle, ARQ087, paclitaxel, carboplatin as single agents, ARQ087 and paclitaxel, ARQ087 and carboplatin, paclitaxel and carboplatin as doublets; and the triple combination of ARQ087 with carboplatin and paclitaxel. Similar experimental setting was applied in nude mice bearing SUN16 xenografts, but instead of paclitaxel, capecitabine was given. The choice of the anticancer agents to be combined with ARQ087 was supported by the fact that these drugs are currently used for the treatment of various cancers clinically. In both experimental settings the drugs given as single agents showed moderate anti-tumor activity. Combination of two agents was more active than the single ones alone and combination of three agents has shown the most antitumor activity. In particular, combination of ARQ 087 with paclitaxel and carboplatin in H1581 bearing mice resulted in tumor regression and only 1/8 tumor re-grew after 30 days from the last drug administration versus 6/8, 4/8 e 5/8 in treatment groups with paclitaxel alone, combination of ARQ087 with paclitaxel, and combination of paclitaxel with carboplatin respectively. Of importance, no toxic deaths nor premature stopping or delaying of drug administration occurred. These data clearly suggest that ARQ087 can be safely combined with chemotherapy and that the combinations are much more active than the monotherapies.

Citation Format: Rosaria Chilà, Federica Guffanti, Terence Hall, Francesca Ricci, Massimo Broggini, Giovanna Damia. Combinations of ARQ087 with chemotherapeutic agents are safe and show a striking antitumor activity in different xenograft models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3500. doi:10.1158/1538-7445.AM2015-3500
Abstract 3503: Gilenya and Alimta interact to kill breast cancer cells
Authors: Roberts Jane L. , Tavallai Seyedmehrad , Poklepovic Andrew , Booth Laurence , Dent Paul
Published: August 2015

The present studies sought to determine whether the anti-folate pemetrexed (Alimta) and the sphingosine-1-phosphate receptor modulator FTY720 (Fingolimod, Gilenya) interacted to kill tumor cells. FTY720 and pemetrexed interacted in a greater than additive fashion to kill breast, brain and colorectal cancer cells. Loss of p53 function weakly enhanced the toxicity of FTY720 whereas deletion of activated RAS strongly or expression of catalytically inactive AKT facilitated killing. In contrast, expression of activated forms of AKT, p70 S6K and mTOR or inhibition of JNK and p38 MAPK suppressed the toxic interaction between FTY720 and pemetrexed. Indeed, combined drug exposure reduced the activity of AKT, p70 S6K and mTOR and activated JNK and p38 MAPK. Expression of activated forms of AKT, p70 S6K and mTOR or inhibition of JNK and p38 MAPK suppressed the toxic interaction between FTY720 and pemetrexed. Treatment of cells with FTY720 and pemetrexed increased the numbers of autophagosomes in cells that correlated with increased LC3 processing and increased p62 levels. Knock down of ATG5 or Beclin1 suppressed autophagosome formation and cell killing by the drug combination. Sorafenib was previously shown to potently interact with pemetrexed to kill tumor cells. Sorafenib significantly enhanced the lethality of [FTY720 + pemetrexed] treatment in vitro and in vivo. Collectively our findings argue that pemetrexed, sorafenib and FTY720 could be a novel adjunct modality for breast cancer treatment.

Note: This abstract was not presented at the meeting.

Citation Format: Jane L. Roberts, Seyedmehrad Tavallai, Andrew Poklepovic, Laurence Booth, Paul Dent. Gilenya and Alimta interact to kill breast cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3503. doi:10.1158/1538-7445.AM2015-3503
Abstract 3506: Targeting breast cancer stem cells and non-stem breast cancer cells through combination therapies
Authors: Hii Ling-Wei , Chung Felicia Fei-Lei , Tan Boon-Shing , Lim Yang Mooi , Cheong Soon-Keng , Leong Chee-Onn
Published: August 2015

Cancer stem cells (CSCs), as a subset of tumor cells with enhanced capacity to generate tumors, have recently been attributed to driving cancer recurrence and metastasis. Although the current CSC model highlights the importance of developing strategies to target CSCs, it is conceivable that the depletion of CSCs within a tumor would not lead to complete regression since non-CSCs might still be capable of sustaining tumor growth or regaining CSC potential. As either of these possibilities would confound the effectiveness of therapeutic agents that exclusively target CSCs, we aimed to rapidly identify combination therapies that could synergistically target both breast cancer cells and breast CSCs. Using a comprehensive small chemical library screen consisting of more than 1600 compounds, we identified a total of 193 small molecules, including 45 FDA approved drugs, which could target both breast CSCs and non-CSCs. When combined with conventional chemotherapeutic agents (e.g. cisplatin, doxorubicin or paclitaxel), histone deacetylase (HDAC) inhibitors exhibited significant synergistic effects in targeting both breast CSCs and non-CSCs. In summary, our data suggests that HDAC inhibitors represent a class of agents that could synergize with chemotherapeutic agents in refractory breast cancer cells and warrant further investigations.

Citation Format: Ling-Wei Hii, Felicia Fei-Lei Chung, Boon-Shing Tan, Yang Mooi Lim, Soon-Keng Cheong, Chee-Onn Leong. Targeting breast cancer stem cells and non-stem breast cancer cells through combination therapies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3506. doi:10.1158/1538-7445.AM2015-3506
Abstract 3520: Small molecule inhibitors of ring1B-Bmi1 E3 ligase target polycomb repressive complex 1 activity and regulate cell proliferation
Authors: Shukla Shirish , Zhao Qingjie , Ying Weijang , Gray Felicia , Vandenberg Kelly , Lund George , Boytsov Bohdan , He Shihan , Grembecka Jolanta , Cierpicki Tomasz
Published: August 2015

Emerging evidence implicates the role of Ring1B and Bmi1 in the maintenance of embryonic stem cells and regulating adult stem cells self-renewal. Both Ring1B and Bmi1 are part of Poly-comb Repressive Complex 1(PRC1) and execute gene silencing through histone H2A lysine119 ubiquitination (UbH2A K119). In addition, Bmi1 is also required for the self-renewal capacity of leukemic stem cells, suggesting that Poly-comb Group proteins may contribute to oncogenic transformation by regulating stem cell self-renewal. Targeting cancer stem cell self-renewal has been proposed as a therapeutic goal and could be an effective approach to control tumor growth. In this study, we report the development and characterization of small molecule inhibitors against Ring1B-Bmi1 complex which interfere with its E3 ligase function. We developed ligands binding to Ring1B-Bmi1 employing NMR fragment-based screening. We further performed extensive medicinal chemistry optimization and synthesized over 80 analogs of the initial fragment hit and improved its binding affinity to Ring1B-Bmi1 complex by more than 1000-fold. The activity of developed small molecule inhibitors was analyzed by cellular and biochemical studies including in vitro ubiquitination assay and quantitative analysis of p16 expression. Mechanistically, we found that our most potent compounds inhibit E3 ligase activity of Ring1B-Bmi1 at low micromolar concentrations. As expected, treatment of HeLa and leukemic cell lines with these compounds demonstrated reduced UbH2A K119 levels and increased expression of p16. In addition, presence of the lead compounds also reduces leukemic cell proliferation as determined by MTT assays. Furthermore, the comparison between knockdown effects of Ring1B/Bmi1 with small molecule inhibitors revealed on target effect of the lead compounds. To our knowledge, these compounds represent the first small molecule inhibitors that directly bind to Ring1B-Bmi1 and inhibit its E3 ubiquitin ligase activity and have a strong potential for further development into potent anticancer agents.

Citation Format: Shirish Shukla, Qingjie Zhao, Weijang Ying, Felicia Gray, Kelly Vandenberg, George Lund, Bohdan Boytsov, Shihan He, Jolanta Grembecka, Tomasz Cierpicki. Small molecule inhibitors of ring1B-Bmi1 E3 ligase target polycomb repressive complex 1 activity and regulate cell proliferation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3520. doi:10.1158/1538-7445.AM2015-3520
Abstract 3531: Companion diagnostics-based telomerase-specific oncolytic virotherapy: preclinical evaluation in human colorectal cancer cell lines differentially affected in the RAS/RAF/MEK signaling pathway
Authors: Tamura Shuta , Tazawa Hiroshi , Hori Naoto , Koujima Takeshi , Kikuchi Satoru , Kuroda Shinji , Kishimoto Hiroyuki , Nagasaka Takeshi , Nishizaki Masahiko , Urata Yasuo , Kagawa Shunsuke , Fujiwara Toshiyoshi
Published: August 2015

Colorectal cancers harboring KRAS or BRAF mutations often show resistance to anti-cancer drugs, and are poor prognostic disease that causes metastasis and recurrence compared to those with wild type KRAS and BRAF. KRAS/BRAF-wild type colorectal cancers are sensitive to both cetuximab and panitumumab that are epidermal growth factor receptor (EGFR)-targeting agents. However, KRAS/BRAF-mutant colorectal cancers are resistant to EGFR-targeting agents because of constitutive activation of the EGFR-downstream RAS/RAF/MEK signaling pathway. Therefore, the development of novel therapeutic strategy is required to improve the clinical outcome in patients with KRAS/BRAF-mutant colorectal cancers. We developed two types of telomerase-specific replication-competent oncolytic adenoviruses, OBP-301 and OBP-702 armed with the wild-type p53 tumor suppressor gene. In this study, we established the companion diagnostics-based selection algorithm for our oncolytic viruses. We compared the antitumor effects of OBP-301 and OBP-702 in human colorectal cancer cells with wild type KRAS/BRAF (SW48, Colo320DM), mutated KRAS (DLD-1, SW620) and mutated BRAF (RKO, HT29). We evaluated the antitumor effect of OBP-301 and OBP-702 in human colorectal cancer cells using XTT assay. Oncolytic adenovirus-mediated induction of apoptosis- and autophagy-related cell death was analyzed by Western blot analysis. KRAS-mutant colorectal cancer cells were sensitive to both OBP-301 and OBP-702 as well as KRAS/BRAF-wild type cells. In contrast, BRAF-mutant colorectal cancer cells were sensitive to OBP-702 rather than OBP-301. Western blot analysis showed that OBP-301 induced autophagy, whereas OBP-702 induced both autophagy and apoptosis. Taken together, our data suggest that oncolytic viruses should be used according to the genetic background of the RAS/RAF/MEK signaling pathway, especially in patients with colorectal cancer.

Citation Format: Shuta Tamura, Hiroshi Tazawa, Naoto Hori, Takeshi Koujima, Satoru Kikuchi, Shinji Kuroda, Hiroyuki Kishimoto, Takeshi Nagasaka, Masahiko Nishizaki, Yasuo Urata, Shunsuke Kagawa, Toshiyoshi Fujiwara. Companion diagnostics-based telomerase-specific oncolytic virotherapy: preclinical evaluation in human colorectal cancer cell lines differentially affected in the RAS/RAF/MEK signaling pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3531. doi:10.1158/1538-7445.AM2015-3531
Abstract 3565: Gli2 induces melanoma tumor growth and progression: A critical role of c-Myc
Authors: Fofaria Neel Manoj , Srivastava Sanjay K.
Published: August 2015

Gli2 is one of the key transcription factors in sonic hedgehog (Shh) pathway. Aberrant activation of Gli2 has been reported in several malignancies. However, the role of Gli2 in melanoma progression is unclear. Our results showed that knock down of Gli2 in melanoma cells inhibited the proliferation as well as induced apoptosis in melanoma cells in vitro, which was associated with down-regulation of c-Myc. Melanoma cells with stable Gli2 knockdown demonstrated diminished tumor growth when injected subcutaneously in athymic nude mice. In addition, Gli2 inhibitors GANT58 and GANT61 significantly inhibited the growth of melanoma cell lines. Furthermore, oral administration of 5mg/kg piplartine (PL), an alkaloid inhibited the growth of melanoma tumor xenograft by 84% as compared to control. The tumor suppression by PL was associated with inhibition of Gli2 and c-Myc as observed by western blot and immunohistochemistry analysis. The concentration of PL achieved in plasma was 8.5μM whereas in tumor was 6μmol/gm as analyzed by LC-MS/MS. Interestingly, the IC50 of PL at 48 hours was around 3-4μM in a panel of 15 melanoma cells lines, correlating well with the concentrations achieved in vivo. Melanoma cells treated with 2.5, 5 and 7.5μM PL for 48 hours induced significant apoptosis, with concomitant inhibition of Gli2 as well as c-Myc. Gli2 overexpression and treatment with Shh ligand significantly blocked PL mediated inhibition of cell proliferation and induction of apoptosis, establishing the role of Gli2 in PL-mediated growth suppression of melanoma cells. PL inhibited nuclear translocation as well as DNA binding of Gli2 as observed by analysis of Gli2 in nuclear fraction and Chromatin Immunoprecipitation (ChIP) assay, indicating the importance of Gli2 transcriptional activity in melanoma cell proliferation. In conclusion, our results provide convincing evidence that Gli2 mediated induction of c-Myc plays an important in melanoma tumor growth and subsequently establishes that PL mediated inhibition of melanoma cells in vitro and in vivo is associated with inhibition of Gli2. [Supported in part by R01 grant CA129038 (to S.K.S) awarded by the National Cancer Institute].

Citation Format: Neel Manoj Fofaria, Sanjay K. Srivastava. Gli2 induces melanoma tumor growth and progression: A critical role of c-Myc. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3565. doi:10.1158/1538-7445.AM2015-3565
Abstract 3577: Targeting localization and function of the RNA helicase DDX5/p68 with 1-(3,5-dimethoxyphenyl)-4-[(6-fluoro-2-methoxyquinoxalin-3-yl) aminocarbonyl] piperazine (RX-5902)
Authors: Remenyi Judit , Yang Mi Young , Lee Young Bok , Kim Deog Joong , Fuller-Pace Frances V.
Published: August 2015

The DEAD box RNA helicase DDX5/p68 is aberrantly expressed and post-translationally modified in several cancers. Several studies have indicated that p68 plays important roles in cell proliferation and tumor progression; in particular, p68 that is phosphorylated on Tyr593 has been shown to be associated with cell transformation, epithelial mesenchymal transition and cell migration. Therefore, p68 may be a promising target for novel anti-cancer therapeutics.

We previously reported that 1-(3,5-dimethoxyphenyl)-4-[(6-fluoro-2-methoxyquinoxalin-3-yl) aminocarbonyl] piperazine (RX-5902) inhibits the growth cancer cell lines by interacting and interfering with the function of phosphorylated p68 at low nanomolar concentrations, and inhibit tumor growth in several human xenograft models in nude mice.

Although p68 is largely a nuclear protein, it has been found to shuttle between the nucleus and cytoplasm in cells, a function that appears to be critical for its role in epithelial-mesenchymal transition. Furthermore, our previous work demonstrated that the nuclear localization of p68 alters during the cell cycle suggesting that alterations in localization of p68 may also be important for cell cycle control and proliferation.

We therefore investigated the effect of RX-5902 on the cellular localization of phosphorylated p68 in cancer cell lines. Our results suggest that treatment with RX5902 results in a significant alteration in the localization of phosphorylated p68, providing a possible mechanism(s) by which RX-5902 may affect phosphorylated p68 function. Further ongoing studies are aimed at examining the effect of RX-5902 on cellular motility in wound healing assays to determine whether RX-5902 could additionally affect the potential function of phosphorylated p68 in cell migration.

Citation Format: Judit Remenyi, Mi Young Yang, Young Bok Lee, Deog Joong Kim, Frances V. Fuller-Pace. Targeting localization and function of the RNA helicase DDX5/p68 with 1-(3,5-dimethoxyphenyl)-4-[(6-fluoro-2-methoxyquinoxalin-3-yl) aminocarbonyl] piperazine (RX-5902). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3577. doi:10.1158/1538-7445.AM2015-3577
Abstract 3585: HER3 and IGF1R are major mediators of both acquired and intrinsic cetuximab resistance in head and neck squamous cell carcinomas
Authors: Kjaer Ida , Lindsted Trine , Fröhlich Camilla , Horak Ivan D. , Kragh Michael , Olsen Jesper V. , Pedersen Mikkel W.
Published: August 2015

Head and neck squamous cell carcinoma (HNSCC) is among the leading causes of death worldwide. HNSCC originates from the squamous epithelium of the upper aerodigestive tract, including the lip, oral cavity, pharynx, larynx and paranasal sinuses. The epidermal growth factor receptor (EGFR) has been found to play an essential role in driving the malignancy of HNSCC. The monoclonal antibody targeting EGFR, cetuximab, has been approved for clinical use in HNSCC patients, in combination with either radiation or chemotherapy. However, intrinsic and acquired cetuximab resistance is a major problem for effective therapy. Thus, a better understanding of the mechanisms responsible for cetuximab resistance is valuable for development of the next generation of antibody therapeutics.

In order to investigate the molecular mechanisms behind cetuximab resistance in HNSCC, we screened a panel of cell lines for sensitivity to cetuximab. As expected, the cell lines exhibited a varied response to cetuximab. The most sensitive cell line, HN5, was used to establish a number of cetuximab-resistant clones. These resistant clones had lower EGFR levels but remained partially dependent on EGFR, as demonstrated by EGFR gene knockdown and treatment with a mixture of two anti-EGFR antibodies.

HER3 and IGF1R are known to be major drivers of resistance to EGFR targeting therapies, and therefore we investigated the role of the two receptors in resistant clones with a mixture of antibodies against EGFR, HER3 and IGF1R. The antibody mixture, which simultaneously blocked EGFR, HER3 and IGF1R signaling, resulted in near total growth inhibition of cetuximab resistant clones. These results were extended to HNSCC cell lines with intrinsic resistance to cetuximab and also in these cell lines the three target mAb mixture led to effective growth inhibition.

In conclusion, our results demonstrate that HNSCC cell lines have a heterogeneous response to cetuximab and that HER3 and IGF1R effectively compensate for EGFR inhibition in both the acquired and intrinsic cetuximab resistant setting. Our results thus provide a rationale for simultaneous targeting of EGFR, HER3, and IGF1R in HNSCC.

Citation Format: Ida Kjaer, Trine Lindsted, Camilla Fröhlich, Ivan D. Horak, Michael Kragh, Jesper V. Olsen, Mikkel W. Pedersen. HER3 and IGF1R are major mediators of both acquired and intrinsic cetuximab resistance in head and neck squamous cell carcinomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3585. doi:10.1158/1538-7445.AM2015-3585
Abstract 3597: EZH2 D1 domain mutants confer acquired resistance to EZH2-targeted inhibitors and reprogram B-cell transcription
Authors: Gonzalvez Francois , Baker Theresa , Pritchard Justin , Rivera Victor M. , Garner Andrew
Published: August 2015

Aberrant epigenetic changes play an important role in the onset and progression of numerous tumor types, and targeting enzymes that regulate these processes holds significant promise for cancer treatment. The identification of Y641 and A677 oncogenic mutations in the histone methyl-transferase EZH2 in hematological cancers and melanoma, has led to a surge of interest in exploring the therapeutic potential of targeting EZH2. Several potent and selective small-molecule inhibitors targeting EZH2 (EZH2i) have recently been generated. The most advanced compounds, EPZ-6438 (E7438) and GSK126 (GSK2816126), are currently tested in lymphoma and advanced solid tumors, with EPZ-6438 exhibiting preliminary evidence of efficacy (ENA, 2014). As observed with other targeted cancer therapies, acquired resistance may pose a major clinical challenge to EZH2i. However, at this early stage in clinical development, mechanisms of acquired resistance to EZH2i remain unidentified. Nonetheless, it is critical to anticipate future clinical resistance mechanisms in order to develop effective patient treatment strategies.

To explore EZH2i resistance, we used an innovative forward genetic approach that combined a mutagenesis screen with next-generation sequencing technologies. Using this strategy, we identified a hotspot of EZH2 missense mutations (Y111 and I109) that conferred cross-resistance to both EPZ-6438 and GSK126. Surprisingly, the mutation hotspot lies outside the EZH2 catalytic region in its D1 domain, signifying a unique allosteric mechanism of drug resistance. Importantly, to drive resistance, the EZH2 mutants still required an active histone methyl-transferase catalytic domain and the main components of the polycomb repressive complex 2. Furthermore, we also uncovered an unexpected neomorphic role for these mutations in controlling the expression of genes typically involved in B-cell differentiation. This work describes the first evidence of acquired resistance to EZH2i, and identifies potential clinically relevant resistance mutations. Moreover, our findings provide new mechanistic insights into the function of EZH2, and importantly, suggest that acquired-resistance to EZH2i may arise in the clinic in a manner that remains targetable by inhibitors, thus, providing a foundation for the discovery of second-generation EZH2i to treat relapsed patients.

Citation Format: Francois Gonzalvez, Theresa Baker, Justin Pritchard, Victor M. Rivera, Andrew Garner. EZH2 D1 domain mutants confer acquired resistance to EZH2-targeted inhibitors and reprogram B-cell transcription. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3597. doi:10.1158/1538-7445.AM2015-3597
Abstract 3598: Selective internal radiation (SIRT) is most effective when comparing local treatment to control progressive liver metastases of gastro-intestinal stromal tumors beyond treatment with tyrosine kinase inhibitors
Authors: Hohenberger Peter , Rathmann Nils , Menge Franka , Sadick Maliha , Schönberg Stefan , Diehl Steffen
Published: August 2015

Objective: The liver and the peritoneum are the main area of metastatic spread in gastrointestinal stromal tumors (GIST). Liver surgery plays a minor role for hepatic metastases in comparison to f.e. colorectal cancer. However, once the metastases are resistant to 1st line TKI, surgery, 2nd line therapy, interventional ablation techniques like RFA or selective internal radiation therapy (SIRT) are treatment options. We were interested to analyze the contribution of the different modalities in controlling hepatic progression.

Methods: 731 pts with biopsy proven GIST were followed since 2004 (median follow-up 43.6 months); data were prospectively documented. There were 337 males (46.1%) and 101 (13.8%) pts. presented with M1 disease initially. Of the remaining 630 pts, 358 pts (56.8%) developed tumor recurrence after a median time interval of 22 months. 312/358 pts (87%) developed metastases within the abdomen: liver n = 96, peritoneal n = 97, liver+peritoneal n = 78, locoregional n = 10, locoreg.+hep/per n = 21. Imatinib was the initial treatment in all patients with M1 disease.

Results: Out of 205 patients with liver metastases, 118 remained controlled by drug therapy or showed multi-site progression. In the remaining 87 pts., 26 pts each underwent liver resection or 2nd/3rd line drug therapy (sunitinib, regorafenib), 22 pts had RFA and 13 pts were treated by SIRT. Follow-up was done via dynamic MRI and contrast-enhanced (CE)-CT. The median hepatic-progression free survival (H-PFS) was 15.9 months (4-29) after SIRT (with 3 CR, 6 PR), however, only 5.6 (range, 2 - 13) months after 2nd line drug, 8.2 (3-15) months after surgery, and 7.7 (5-14) months after RFA, p<0.02.

Conclusion: 90Y radiation loaded particles (SIRT) provides the best hepatic progression free survival when compared to 2nd line drugs, RFA or even surgery in imatinib resistant GIST liver metastases. The effect could be mediated by eliminating small (subclinical, micro-) metastases. In patients known to have a GIST resistant to known TKIs, such as wildtype (non-KIT, non-PDGFRA mutated f.e. NF1-associated) lesions, SIRT could be used in earlier treatment lines.

Citation Format: Peter Hohenberger, Nils Rathmann, Franka Menge, Maliha Sadick, Stefan Schönberg, Steffen Diehl. Selective internal radiation (SIRT) is most effective when comparing local treatment to control progressive liver metastases of gastro-intestinal stromal tumors beyond treatment with tyrosine kinase inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3598. doi:10.1158/1538-7445.AM2015-3598
Abstract 36: Cross-talk of the cytokine pathways in cancer progression
Authors: Bakin Andrei V. , Limoge Michelle , Beattie Amy
Published: August 2015

Anti-inflammatory TGFβ and pro-inflammatory TNFα/IL1β cytokines are among the major cytokines in tumor microenvironment that drive cancer progression and metastasis. Published studies implicate TGFβ-activated protein kinase TAK1 as an important mediator in cytokine-driven tumor invasion and metastasis. TAK1 is an ubiquitin-dependent protein kinase that can activate NFκB and MAPK signaling cascades. This study addressed several foremost questions such as a) what signaling cascade is activated by the cytokine crosstalk and what are major transducers and effectors of this crosstalk; b) whether a crosstalk is associated with a specific genetics or cell type, for example a specific molecular subtype of breast cancer. Molecular profiling study identified a TAK1-dependent molecular signature and revealed a close association of the TAK1 molecular signature with triple-negative breast cancers. The cytokines synergistically stimulated expression of a set of pro-invasive and pro-metastatic molecules including matrix metalloproteinase 9 (MMP9). shRNA screening study identified specific molecular transducers of TAK1 that mediate MMP9 expression and cell motility. In particular, our study found an essential role of RELA but not NFKB2 in regulation of MMP9. Addressing a signaling crosstalk, we found that TGFβ and TNFα robustly activated a significant level of canonical signaling via SMADs and RELA/NFkB, respectively, but neither of these cytokines cross-talked to stimulate canonical transducers for a respective cytokine. Instead, TGFβ and TNFα synergized in activation of MAPK signaling and up-regulation of specific transcription targets of the cytokine pathways. In summary, anti-inflammatory TGFβ and pro-inflammatory TNFα cytokines synergize in stimulation of tumor invasion and metastatic potential by cooperating in TAK1-mediated regulation of MAPK signaling and expression of target genes. A TAK1 molecular signature is associated with triple-negative breast cancers.

Citation Format: Andrei V. Bakin, Michelle Limoge, Amy Beattie. Cross-talk of the cytokine pathways in cancer progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 36. doi:10.1158/1538-7445.AM2015-36
Abstract 360: Senescent hepatocytes secrete CCL2 to accelerate liver cancer growth via accumulation of immunosuppressive myeloid cells
Authors: Eggert Tobias , Ji Juling , Zender Lars , Wang Xin Wei , Greten Tim F.
Published: August 2015

Aim: Oncogene-induced senescence causes hepatocytes to secrete cytokines, which induce the immune-mediated clearance of these senescent cells, preventing malignant transformation and tumor initiation; a process termed ‘senescence surveillance’. However, senescent hepatocytes can give rise to hepatocellular carcinomas (HCC), if additional oncogenic mutations, e.g. p53 mutation, abrogate the senescence program. We set out to investigate the effect of senescent cell secreted cytokines on growth of neighboring liver tumor cells.

Experimental procedure: To induce senescence in mouse livers, we hydrodynamically injected a transposon system, which encodes for either oncogenic Nras (NrasG12V) or an effector loop mutant (NrasG12V/D38A) that is incapable of signaling to downstream pathways, into C57BL/6 or CCR2-/- mice. To achieve tumor development in senescent livers, hepatocellular carcinoma cells were intrasplenically injected into mice, which expressed either NrasG12V or NrasG12V/D38A in the liver. Hepatic immune cell infiltrates were analyzed using flow cytometry and immunohistochemistry. Immunosuppressive ability of CD11b+Gr1+ myeloid cells was analyzed in vitro after fluorescence-activated cell sorting. Furthermore, peritumor tissue of 226 HCC patients was hierarchical clustered based on the expression of 35 senescence-associated genes. Senescence-associated gene signature was then compared with CCL2 expression and survival.

Results: Senescent hepatocytes promoted growth of hepatocellular carcinoma cells through accumulation of immunosuppressive CD11b+Gr1+ myeloid cells. CD11b+Gr1+ cells inhibited T cell proliferation via an iNOS-dependent mechanism. Immunosuppressive myeloid cell accumulation as well as tumor growth promotion was abrogated, when senescence was induced in livers of CCR2 knockout mice, indicating a pivotal role for CCL2 in creating a tumor promoting immune environment. Finally, gene expression analysis in patients with hepatocellular carcinoma confirmed the association of senescence-induced CCL2 expression in peritumor tissue and poor prognosis.

Conclusion: Senescent hepatocytes not only induce an inflammatory response that leads to their own clearance, preventing tumor initiation, but surprisingly also induce the accumulation of immunosuppressive myeloid cells that promote growth of neighboring hepatocellular carcinomas.

Citation Format: Tobias Eggert, Juling Ji, Lars Zender, Xin Wei Wang, Tim F. Greten. Senescent hepatocytes secrete CCL2 to accelerate liver cancer growth via accumulation of immunosuppressive myeloid cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 360. doi:10.1158/1538-7445.AM2015-360
Abstract 3608: Prostaglandin E-2 promotes resistance to oxaliplatin in colorectal cancer cells
Authors: Huang Huakang , Rosenberg Daniel W.
Published: August 2015

Oxaliplatin, a platinum-based DNA crosslinking agent, has been used successfully as a first-line chemotherapeutic agent for the treatment of metastatic colorectal cancer (CRC). However, long-term treatment with oxaliplatin results in resistance in nearly all patients, limiting its therapeutic efficacy. Previous studies have shown that treatment of CRC cells with selective inhibitors of the enzyme Cyclooxygenase-2 (COX-2) leads to the development of drug resistance. One of the terminal products of the COX-2 pathway, prostaglandin E-2 (PGE2), is a pro-inflammatory lipid that has been implicated in colorectal tumorigenesis; however, it is unknown whether PGE2 plays a role in the development of drug resistance. In this study, we have begun to investigate the relationship between PGE2 and oxaliplatin resistance using the human CRC cell lines, HT29 and HCT116. Oxaliplatin-resistant HT29 cells (HT29-OXR) were generated by continuous exposure of parental HT29 cells to increasing concentrations of oxaliplatin over a period of 3 months. We have found that HT29-OXR cells produce significantly higher levels of PGE2 (3-fold increase, p<0.05) compared to the parental HT29 cell line. In addition, we have observed concomitantly elevated levels of the terminal PGE2 synthase, microsomal prostaglandin E synthase-1 (mPGES-1). Furthermore, we have demonstrated that the addition of exogenous PGE2 to both parental HT29 and HCT116 cells significantly (p<0.0001) decreased their sensitivity (IC50) to oxaliplatin, measured by the MTT cell viability assay. These findings suggest that PGE2 promotes resistance to oxaliplatin in CRC cells. FACS analysis showed that co-treatment of HT29 cells with exogenous PGE2 for 24 hours leaded to 27% reduction in oxaliplatin-induced Annexin V staining for early apoptosis, while exogenous PGE2 maintained G2/M arrest and simultaneously reduced the proportion of dead sub-G1 cells by approximately 80.4% in parental HCT116 cells. Our findings reveal a role for PGE2 in oxaliplatin resistance, possibly via regulation of apoptosis, and provide new data suggesting that targeting mPGES-1 may be a useful strategy for overcoming oxaliplatin resistance.

Citation Format: Huakang Huang, Daniel W. Rosenberg. Prostaglandin E-2 promotes resistance to oxaliplatin in colorectal cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3608. doi:10.1158/1538-7445.AM2015-3608
Abstract 3612: Study of the functional importance of PPARγ in honokiol-induced apoptosis of hepatoma cells
Authors: Chi Chin-Wen , Hsu Hui-Tzu , Hou Jia-Dong , Lee Chih-Chun , Kuo Ying-Ju , Lee Hsin-Chen , Hsia Cheng-Yuan
Published: August 2015

Hepatocellular carcinoma (HCC) is the leading cause of death in male cancer patients in Asia. PPARγ exhibited an inhibitory role in hepatocarcinogenesis in vitro and in vivo. Recently, it was found that honokiol functions not only as a RXR agonist but also a PPARγ agonist, and is capable of potentiating the activation of PPARγ in the presence of PPARγ agonist rosiglitazone in HLE human hepatoma cells. It also has been reported that honokiol exerts inhibitory effects on the growth and migration in hepatoma cells. However, whether PPARγ overexpression modulates the honokiol-induced growth inhibition in hepatoma cells is not known. Firstly, we examined the expression of PPARγ in tumor samples from 83 HCC patients by immunohistochemical staining. Our results showed that 53 samples had no PPARγ and the clinical parameters including tumor number, stages, and macroscopic vascular invasion (MVI) showed significant negative correlation with PPARγ expression. However, the expression of PPARγ was not associated with disease free survival or overall survival of patients with HCC. Using PPARγ overexpressed SK-Hep1 cells (SK-Hep1-PPARγ) for in vitro analyses, we found that 40 μM honokiol treatment of SK-Hep1-PPARγ cells induced a 20% increase of growth inhibition at 48 hour as compared to vector control cells by MTT assay. This corresponded well with the 15% increase in G0/G1 phase after honokiol treatment at 24 hour compared to vector control cells. In addition, honokiol treatment resulted in decreased cyclin D1, increased p21 and KLF4 expressions in SK-Hep1-PPARγ cells. Moreover, miRNA array analyses showed that increased expression of miR-222, let-7i, miR-628-3p and miR-664 as well as decreased miR-1291, miR184 and miR1249 were observed in SK-Hep1-PPARγ cells. In conclusion, PPARγ is not only a biomarker for prognosis of patients with HCC but also play an important role in the honokiol-induced growth inhibition of hepatoma cells. The functional importance of PPARγ regulated miRNA is currently under further investigation.

Citation Format: Chin-Wen Chi, Hui-Tzu Hsu, Jia-Dong Hou, Chih-Chun Lee, Ying-Ju Kuo, Hsin-Chen Lee, Cheng-Yuan Hsia. Study of the functional importance of PPARγ in honokiol-induced apoptosis of hepatoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3612. doi:10.1158/1538-7445.AM2015-3612
Abstract 3629: Balance shift between error-free and error prone DNA double-strand break repair as a novel mechanism of radiosensitization by nucleoside analogs
Authors: Iliakis George , Magin Simon
Published: August 2015

Nucleoside analogs (NAs) represent a large group of anticancer drugs, several members of which have been shown to sensitize cells to ionizing radiation (IR). Among the lesions induced in cells by IR, the DNA double-strand break (DSB) is considered to be the most detrimental. Therefore we focused on interactions between NAs and pathways of DSB repair.

We opted for post-irradiation treatment with NAs to avoid complications arising from redistribution of cells throughout the cycle prior to IR exposure. We compared the effects of 4h treatments post-IR with vidarabine (ara-A), fludarabine (F-ara-A) or gemcitabine (dFdC) on the survival of A549 lung carcinoma cells. We found that post-irradiation treatment with ara-A and F-ara-A, but not dFdC, resulted in cell radiosensitization to killing. Radiosensitization by ara-A was superior to that by F-ara-A. We employed immunofluorescence detection of IR-induced foci and I-SceI-based reporter cell lines to identify the pathways of DSB repair that are inhibited by ara-A and cause the observed radiosensitization. We found that the formation of IR-induced Rad51-foci was compromised by ara-A suggesting inhibition of homologous recombination repair (HRR). Repair of I-SceI-induced DSBs by HRR was also suppressed by ara-A. Furthermore, A549 cells deprived of Rad51 by RNAi could not be efficiently radiosensitized by ara-A. On the other hand, we could not detect impairment by ara-A of non-homologous end-joining (NHEJ), as measured by pulsed-field gel electrophoresis (PFGE) at high doses of IR (20 Gy). Notably, we observed an increase in the frequency of mutagenic NHEJ events in several I-SceI-based repair reporter systems, indicative of processing by error-prone repair pathways such as alternative/backup NHEJ (B-NHEJ). In addition, we could show that treatment with ara-A induces a dramatic increase in B-NHEJ in plateau phase Lig4-/- MEFs. Treatment with F-ara-A also inhibited HRR, but was less proficient in promoting mutagenic NHEJ.

We conclude that inhibition of HRR and promotion of B-NHEJ represent two important mechanisms of radiosensitization by NAs. The strong impact of ara-A on both of these repair pathways underpins its superior radiosensitizing potential. Targeting of both HRR and B-NHEJ may provide a promising new strategy for radiosensitization.

Citation Format: George Iliakis, Simon Magin. Balance shift between error-free and error prone DNA double-strand break repair as a novel mechanism of radiosensitization by nucleoside analogs. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3629. doi:10.1158/1538-7445.AM2015-3629
Abstract 3633: Combination of PARP inhibitor ABT-888 with NO-donor SNAP sensitizes BRCA1 positive cancer cell lines to ionizing radiation
Authors: Wilson Aaron , Yakovlev Vasily A.
Published: August 2015

Loss or inhibition of Poly(ADP-ribose) polymerase 1 (PARP1) activity results in accumulation of DNA single-strand breaks, which are subsequently converted to DNA double-strand breaks (DSBs) by the cellular replication and/or transcription machinery. Breast cancer type 1 susceptibility protein (BRCA1) is essential for homologous recombination repair (HRR) of DNA DSB. In BRCA-positive cells, DSBs are repaired by HRR, but they cannot be properly repaired in BRCA-deficient cells, leading to genomic instability, chromosomal rearrangements, and cell death.

The role of PARP1 in the DNA damage response promoted the development of PARP inhibitors (PARPi) as chemo- and radio-sensitizers for the treatment of cancers harboring mutations in the BRCA genes. However, inherited BRCA1 or BRCA2 mutations account for 5-10% of breast cancers and 10-15% of ovarian cancers. Hence, a low frequency of BRCA1 loss in non-hereditary tumors can limit the clinical use of this approach.

Our recent work revealed significant down-regulation of BRCA1 gene expression by nitric oxide donors (NO-d) (Yakovlev, 2013). Hence, we assumed that combination of NO-d with PARP inhibitors could be effective in sensitization of the BRCA1-positive tumors to DNA-damaging therapy.

We identified the optimal concentrations of PARPi ABT-888 at 20μM and NO-d SNAP at 200μM, which don't affect cell survival, but effectively block PARP1 activity or BRCA1 expression accordingly. Next, cancer cell lines were pretreated with ABT-888 or SNAP, or with they combination and irradiated. Survival curves were determined by clonogenic assay.

Our preliminary data demonstrates significant radiosensitization when combining an NO-d with a PARPi in BRCA1 positive tumor cell lines (Table 1). We plan to test this drug combination on the additional cancer cell lines and on animal models for sensitization to ionizing radiation and to the different chemotherapeutic agents.

Table 1.Clonogenic assay for A-549 and MDA-MB-231 cell lines: survival fraction.IR (Gy)02468A-549Control1.00±0.0380.55±0.0450.23±0.0360.09±0.0070.0242±0.004ABT-8881.00±0.0650.49±0.0310.18±0.0350.05±0.0040.0076±0.001SNAP0.97±0.0850.43±0.0450.16±0.0330.04±0.0080.0091±0.002ABT-888 + SNAP0.71±0.0750.24±0.0420.05±0.0070.01±0.0020.0014±0.0003MDA-MB-231Control1.00±0.0630.44±0.0380.15±0.0270.039±0.0070.0078±0.0007ABT-8880.85±0.0520.28±0.0170.07±0.0090.012±0.0020.0015±0.0005SNAP1.03±0.0380.3±0.0430.10±0.0080.020±0.0040.0034±0.0007ABT-888 + SNAP0.49±0.0660.12±0.0170.02±0.0070.002±0.00040.00013±0.0001

Citation Format: Aaron Wilson, Vasily A. Yakovlev. Combination of PARP inhibitor ABT-888 with NO-donor SNAP sensitizes BRCA1 positive cancer cell lines to ionizing radiation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3633. doi:10.1158/1538-7445.AM2015-3633
Abstract 3643: Targeting the acetyl-lysine binding site of BRD4 with dual nanomolar BET-JAK2 inhibitors: A new anticancer therapeutic strategy
Authors: Gunawan Steven , Muhammad Ayaz , Ember Stuart W. J. , Zhu Jin-Yi , Jacobsen Rebecca A. , Berndt Norbert , Lambert Que T. , Reuther Gary W. , Lawrence Harshani R. , Schonbrunn Ernst , Lawrence Nicholas J.
Published: August 2015

Bromodomain (BRD)-containing proteins are essential for the recognition of acetylated lysine residues of histones during transcriptional activation. The BRD-containing proteins have emerged as promising drug targets for a number of diseases, including many cancers, that are characterized by changes in the epigenetic cell signature. Recent reports have shown that targeting BRD4 with small molecules may represent a new way to treat prostate and breast cancer, acute myeloid leukemia and melanoma. We have identified many type 1 and type 2 kinase inhibitors which also inhibit BRD4 by robotic co-crystallization screening of kinase inhibitor libraries against BRD4. In each case the co-crystal structure unambiguously revealed the inhibitor bound to the acetyl lysine site of BRD4-1. The identified BRD4 ligands were subjected to differential scanning fluorimetry (DSF) and AlphaScreen assay to assess their binding and inhibitory potentials against BRD4. As shown previously for other BRD-inhibitor-protein complexes, the melting temperatures of BRD4-kinase inhibitor complexes were logarithmically proportional to their IC50 values. We now report the design, synthesis, structural analysis and biological evaluation of next-generation nanomolar BET-selective and nanomolar dual-activity BET-JAK2 inhibitors, based on the initial co-crystallization screening hits. Structure activity relationships were developed using both DSF and co-crystallization of the ligands with BRD4, to assess binding potential and binding modes, respectively. We report initial evaluation of the anticancer potential of compounds possessing dual potent BRD4 and JAK2 inhibitory properties. In addition to myeloma cell lines, this includes the evaluation of dual BRD4-JAK2 inhibitor compounds against JAK2-driven myeloproliferative neoplasm cell lines and primary cells from patients.

Citation Format: Steven Gunawan, Ayaz Muhammad, Stuart W. J. Ember, Jin-Yi Zhu, Rebecca A. Jacobsen, Norbert Berndt, Que T. Lambert, Gary W. Reuther, Harshani R. Lawrence, Ernst Schonbrunn, Nicholas J. Lawrence. Targeting the acetyl-lysine binding site of BRD4 with dual nanomolar BET-JAK2 inhibitors: A new anticancer therapeutic strategy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3643. doi:10.1158/1538-7445.AM2015-3643