bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2958: A cancer-specific monoclonal antibody against podocalyxin developed by CasMab technology inhibited the tumor growth by antibody-dependent cellular cytotoxicity
Authors: Kato Yukinari , Ogasawara Satoshi , Kunita Akiko , Fujii Yuki , Kaneko Mika K.
Published: July 2016

Background: Podocalyxin (PODXL) is a CD34-related sialomucin and a well-known marker of embryonic stem cells. PODXL is expressed in many cancers including brain tumors, breast cancers, and colorectal cancers. Overexpression of PODXL is an independent predictor of progression, metastasis, and poor outcome. In contrast, PODXL is highly expressed in normal cells such as vascular endothelial cells (VECs) or renal podocytes. Although many monoclonal antibodies (mAbs) against PODXL have been established, they bind to both cancer and normal cells. We recently established CasMab technology for developing cancer-specific mAbs, which could target only cancer cells, although those membranous proteins are highly expressed in both cancer and normal cells.

Methods: We immunized mice with human PODXL, which was overexpressed in a glioblastoma cell line. Cancer-specific mAbs were screened using flow cytometry against PODXL-expressing cancer and normal cells. The cancer specificity was confirmed using immunohistochemistry against breast cancer tissues. A mouse-human chimeric anti-PODXL mAb was produced and antibody-dependent cellular cytotoxicity (ADCC) was investigated in vitro. The in vivo efficacy of anti-PODXL mAbs was evaluated using xenograft models of PODXL-expressing cell lines.

Results: One clone of anti-PODXL mAbs, which was established by CasMab technology, reacted with PODXL-expressing many cancer cell lines including breast cancers, brain tumors, and malignant mesotheliomas, whereas it did not bind to VECs in flow cytometry. The anti-PODXL mAb reacted only with PODXL-expressing cancer cells, not with VECs in breast cancer tissues in immunohistochemistry. Furthermore, the anti-PODXL mAb possesses ADCC activity in vitro and anti-tumor effect in vivo.

Conclusion: The anti-PODXL mAb established by CasMab technology could be useful for targeting PODXL in cancer, although PODXL is highly expressed in many normal cells.

Citation Format: Yukinari Kato, Satoshi Ogasawara, Akiko Kunita, Yuki Fujii, Mika K. Kaneko. A cancer-specific monoclonal antibody against podocalyxin developed by CasMab technology inhibited the tumor growth by antibody-dependent cellular cytotoxicity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2958.
Abstract 2960: Potent in vivo activity of site-specific indolino-benzodiazepine antibody-drug conjugates (ADCs) generated via engineered cysteine conjugation
Authors: Yoder Nicholas C. , Bai Chen , Wilhelm Alan , Maloney Erin K. , Ab Olga , Reid Emily E. , Shizuka Manami , Tavares Daniel , Laleau Rassol , Sun Xiuxia , Bogalhas Megan E. , Wang Lintao , Pinkas Jan , Miller Michael L. , Chari Ravi , Keating Thomas A.
Published: July 2016

ADCs are widely studied for cancer therapy, with numerous agents in preclinical and clinical development embodying a wide array of targets, linker chemistries, and cytotoxic effector classes. A fourth element of ADC design that has received much attention recently is the site of conjugation of the cytotoxic molecule to the antibody. Historically, lysine- or interchain cysteine-directed conjugation has been used, but site-specific chemistries have become increasingly popular. Our previous evaluation of site-specific and lysine-linked ADCs utilizing a tubulin-acting maytansinoid effector molecule found the lysine-linked version was more active in vivo (Yoder et al., AACR 2015 #645). Here we present a comparison of engineered cysteine site-specific and lysine-linked ADCs utilizing the previously described indolino-benzodiazepine (henceforth referred to as IGN) effector IGN-P1 (Miller et al., AACR 2015 #652) which is designed to undergo proteolytic cleavage upon cell uptake to release a potently cytotoxic DNA alkylator.

We show that HC-S442C mutants of human IgG1 can be conjugated via maleimide chemistry to IGN-P1 to give stable, potent, and homogeneous ADCs with drug to antibody ratio (DAR) of 2. The in vitro potency of engineered-cysteine IGN-P1 ADCs is largely dependent on the DAR of the ADC, although some difference is observed between HC-S442C and other cysteine mutants used for conjugation.

Pharmacokinetic study of C442 maleimide conjugates suggests that the chemical linkage between effector and antibody is stable upon administration in mice. Further, and in contrast to our previous observations utilizing maytansinoid ADCs, the site-specific and Lys-linked IGN-P1 ADCs showed comparable efficacy in vivo on a molar drug basis. This effect was observed across two different antibodies targeting two different cell surface antigens. These results suggest that, in certain cases, site-specific conjugation chemistry can offer comparable activity to heterogeneous conjugation at well-tolerated doses.

Citation Format: Nicholas C. Yoder, Chen Bai, Alan Wilhelm, Erin K. Maloney, Olga Ab, Emily E. Reid, Manami Shizuka, Daniel Tavares, Rassol Laleau, Xiuxia Sun, Megan E. Bogalhas, Lintao Wang, Jan Pinkas, Michael L. Miller, Ravi Chari, Thomas A. Keating. Potent in vivo activity of site-specific indolino-benzodiazepine antibody-drug conjugates (ADCs) generated via engineered cysteine conjugation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2960.
Abstract 2961: deBouganin conjugated to trastuzumab overcomes multiple mechanisms of T-DM1 drug resistance
Authors: Dillon Rachelle L. , Chooniedass Shilpa , Premsukh Arjune , Adams Gregory P. , Entwistle Joycelyn , MacDonald Glen C. , Cizeau Jeannick
Published: July 2016

DeBouganin is a T-cell epitope-depleted variant of the type I Ribosome Inactivating Protein (RIP) plant toxin Bouganin. DeBouganin binds and deadenylates the sarcin/ricin loop of the 28S subunit of the ribosomal RNA leading to protein synthesis inhibition and apoptosis. To demonstrate the potential advantages of deBouganin over current small molecule payloads, deBouganin was randomly chemically conjugated to trastuzumab with a DAR of approximately 2 and compared to T-DM1 both in vitro and in vivo. The trastuzumab-deBouganin conjugate (T-deB) demonstrated a tighter IC50 range of killing and an overall greater potency in vitro against most cells lines with high levels of Her2 expression as compared to T-DM1. In addition, unlike T-DM1, T-deB was unaffected by inhibitors of multidrug resistance (MDR) and overexpression of Bcl-2 family members. Moreover, T-deB potency was unchanged by Her2-Her3 dimerization in the presence of heregulin. Contrary to T-DM1 which showed only minimal cytotoxicity, T-deB was highly potent in vitro against tumor cells with cancer stem cell (CSC) properties by preventing the formation of tumorspheres. Furthermore, in a BT-474 xenograft study, T-deB was more efficacious than T-DM1 resulting in increased survival of the T-deB treated mice. Overall, the results demonstrate the potency and efficacy of deBouganin and emphasize the importance of using payloads with different MOAs. The data suggest that deBouganin used alone or in combination with other payloads could be a highly effective cancer therapeutic that would provide prolonged clinical benefit.

Citation Format: Rachelle L. Dillon, Shilpa Chooniedass, Arjune Premsukh, Gregory P. Adams, Joycelyn Entwistle, Glen C. MacDonald, Jeannick Cizeau. deBouganin conjugated to trastuzumab overcomes multiple mechanisms of T-DM1 drug resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2961.
Abstract 2972: Development and characterization of synthetic antibodies with a human framework that directly link metabolism to immune system in cancer cells
Authors: Tomic Jelena , McLaughlin Megan , Geyer Ron , Sidhu Sachdev , Moffat Jason
Published: July 2016

Deregulated cellular energetics and evasion of immune system are two hallmark features of cancer cells. In fact, increased uptake of glucose and glutamine by cancer cells elevates flux of a minor glucose pathway known as the hexosamine biosynthetic pathway (HBP), resulting in alteration of glycosylation. Addition of sugar moieties to proteins plays an important role in sensing cellular metabolism, growth factors, signaling molecules, nutrient flux and stress. Since many of these processes are de-regulated in tumorigenesis, global alterations in glycosylation via HBP flux are likely to play an important role in cancer. We hypothesize that cancer cells can “sense” stress through the HBP pathway, and, consequently, reprogram the cell surface and adapt to tougher conditions. Neo-epitopes on the cell surface that emerge from tuning the HBP pathway activity may be prime candidates as readouts that reliably report the status of metabolic reprogramming.

In order to advance the understanding of metabolic reprogramming from the perspective of the cell surface, we combined genetics and advanced protein engineering using phage-displayed synthetic human antibody libraries to generate recombinant antibodies (rAbs) that respond to changes in the activity of the HBP. Our method for discovery of surface and nutrient-associated protein sensors (SNAPS) has allowed us to identify multiple human synthetic rAbs whose activity is potentiated under different metabolic states. More specifically, these rAbs recognize cell surface features that discriminate cancer cells with increased HBP flux and effectively recruit components of the immune system to initiate tumor cell lysis. Our findings suggest that the nutrient-dependent cell surface epitopes may have functional roles in defining cancer cell identity and may link multiple cancer hallmarks.

Citation Format: Jelena Tomic, Megan McLaughlin, Ron Geyer, Sachdev Sidhu, Jason Moffat. Development and characterization of synthetic antibodies with a human framework that directly link metabolism to immune system in cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2972.
Abstract 2979: Dual targeting of HER3 and PIK3CA has potent anti-tumor effects in pre-clinical models of HNSCC
Authors: Khan Nayel , Davis Kara S. , Godse Neal , Kemp Carolyn , Kulkarni Sucheta , Alvarado Diego , LaVallee Theresa , Grandis Jennifer R. , Duvvuri Umamaheswar
Published: July 2016

Background: The phosphoinositide 3-kinase (PI3K) pathway is a frequently mutated oncogenic pathway in head and neck squamous cell carcinoma (HNSCC). This pathway is often further activated by dysregulation of receptor tyrosine kinases, such as the epidermal growth factor receptor family. HER3 has a direct phosphorylation site with the regulatory subunit of PIK3CA, and is being investigated as a potential co-target to increase anti-tumor effects of PI3K inhibition. In this study, we use the human monoclonal antibody KTN3379, which blocks HER3 in the autoinhibited configuration and thus inhibits ligand-independent and ligand, neuregulin β-1,-dependent HER3 activation, and an inhibitor of PIK3CA (BYL719) to determine if HER3 and PIK3CA can be inhibited in a synergistic fashion. KTN3379 and BYL719 are clinical stage compounds and are being evaluated in HNSCC clinical trials.

Methods and Results: Treatment with neuregulin β-1 significantly increased phosphorylation of HER3, AKT, and S6 across HNSCC cell lines, regardless of baseline level of HER3 expression. HER3 inhibition (KTN3379) consistently abrogated these effects and decreased baseline phosphorylation of HER3. Combined blockade of HER3 (KTN3379) and PI3K (BYL719) inhibited the growth of HNSCC cell lines in a synergistic fashion (CI range 0.1-0.5), in both cell proliferation and colony formation assays. This synergy appeared to be less pronounced in HPV-associated cancer cell lines. Combined treatment decreased tumor growth in xenograft models of HNSCC. Furthermore, treatment of some HNSCC cell lines with BYL719 led to upregulation of the HER3 protein in HNSCC cell lines by Western blotting analysis, suggesting a possible role of HER3 in PI3K pathway inhibitor resistance.

Conclusion: HER3 interacts with PI3KCA, and the PI3K pathway in multiple HNSCC cell lines, and combined blockade has synergistic effects in pre-clinical HNSCC models. These findings suggest that HER3 and PI3K dual inhibition may be more effective in tumors that are resistant to mono-therapy with either HER3 or PI3K inhibition alone.

Citation Format: Nayel Khan, Kara S. Davis, Neal Godse, Carolyn Kemp, Sucheta Kulkarni, Diego Alvarado, Theresa LaVallee, Jennifer R. Grandis, Umamaheswar Duvvuri. Dual targeting of HER3 and PIK3CA has potent anti-tumor effects in pre-clinical models of HNSCC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2979.
Abstract 2983: Stat3 regulates supernumerary centrosome clustering in cancer cells via Stathmin/PLK1
Authors: Morris Edward J. , Kawamura Eiko , Gillespie Jordan , McDonald Paul , Muller William , Dedhar Shoukat
Published: July 2016

Centrosome amplification and supernumerary centrosomal content are common features of cancer cells. Such cells must cluster their centrosomes to form a bipolar spindle and achieve productive mitosis. Targeting the mechanisms that allow cells to cluster extra centrosomes is considered a promising cancer therapeutic strategy. We have now identified Stat3, a protein that is frequently activated in many types of cancers and also regulates stem cell function, as a regulator of centrosome clustering in cancer cells. A high content chemical screen for the identification of inhibitors of centrosome clustering identified Stattic, a Stat3 inhibitor, as a centrosome clustering inhibitor. Stat3 depletion in cell lines as well as in tumors in vivo resulted in significant inhibition of centrosome clustering and in decreased tumor viability and growth. Interestingly, we identify a novel, transcription-independent mechanism for Stat3-mediated centrosome clustering that requires activities of Stathmin, a Stat3 interactor involved in microtubule depolymerisation, and polo-like kinase1 (PLK1). Furthermore, stem cell function in PLK4-driven centrosome amplified breast tumor cells is highly sensitive to Stat3 inhibitors, reflected in higher inhibitor sensitivity of tumors derived from these cells in vivo.

We have therefore identified a novel role of Stat3 in the regulation of centrosome clustering, and this role of Stat3 may be critical in identifying tumor types that are sensitive to Stat3 inhibitors.

Citation Format: Edward J. Morris, Eiko Kawamura, Jordan Gillespie, Paul McDonald, William Muller, Shoukat Dedhar. Stat3 regulates supernumerary centrosome clustering in cancer cells via Stathmin/PLK1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2983.
Abstract 2984: Plumbagin induces p53-dependent apoptosis via generation of reactive oxygen species in human cancer cells
Authors: De Umasankar , Kundu Amit , Kim Eunbin , Kwack Jonghwan , Kim Hyungsik
Published: July 2016

Plumbagin [5-hydroxy-2-methyl-1,4-naphthaquinone], a major constituent derived from Drosera and Plumbago, displays antitumor activity both in vitro and animal models, but the molecular mechanisms of p53-mediated antitumor effects have not been clearly explored. The aim of this study is to determine the anticancer effects of plumbagin on MCF-7 (wild type p53) or Ishikawa (p53-mutant type) cells. We compared the cytotoxicity, cell cycle regulation, apoptotic cell death, and generation of intracellular reactive oxygen species (ROS) in these cancer cells. Plumbagin inhibits the growth of Ishikawa (endometrial cancer cells) and SKOV-3 cells, particularly MCF-7 cells. Plumbagin significantly increased the expression of p53 and reduced Murine Double Minute 2 (MDM2) in the MCF-7 cells. Plumbagin up-regulated the expression of p21(CIP1/WAF1) causing cell cycle arrest in the G2/M-phase by down-regulating cyclin B1 and Cdc2 in MCF-7 as well as Ishikawa cells. Plumbagin altered the ratio of Bax/Bcl-2 and cytochrome c released resulting apoptotic cell death in MCF-7 cells. Furthermore, plumbagin dramatically increased the intracellular ROS level, and pretreatment with the ROS scavenger, N-acetyl cysteine (NAC), protected against growth inhibition by plumbagin, suggesting that ROS play a pivotal role in the antitumor activity in MCF-7 cells. In mice bearing the MCF-7 cell xenografts, plumbagin significantly reduced the tumor growth and weight, without apparent side effects. In conclusion, plumbagin exerted anticancer activity in MCF-7 by generation of intracellular ROS that causes induction of apoptosis via Bcl-2/Bax pathways as well as cell cycle arrest.

KEYWORDS: Plumbagin; breast cancer; apoptosis; p53, reactive oxygen species

Citation Format: Umasankar De, Amit Kundu, Eunbin Kim, Jonghwan Kwack, Hyungsik Kim. Plumbagin induces p53-dependent apoptosis via generation of reactive oxygen species in human cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2984.
Abstract 2987: Generation of a selectively cytotoxic fusion protein against p53 mutated cancers
Authors: Epenetos Agamemnon A. , Kousparou Christina , Filipovic Aleksandra
Published: July 2016

The most common genetic alteration in human cancer involves the p53 tumor suppressor gene resulting in defective control of cell cycle arrest and death.

The p53 protein induces a cyclin-dependent kinase (cdk) inhibitor, p21 which occupies a central position in cell cycle regulation. Cdk inhibition by p21 results in a lack of progression from the G1 to the S-phase due to the prevention of retinoblastoma (Rb) phosphorylation and subsequent inhibition of transcription factors that regulate the genes involved in DNA replication and cell-cycle progression.

It is hypothesized that the re-introduction of p21 into tumor cells will regenerate the pathway to apoptosis (programmed cell death) and inhibit proliferation since it has been suggested that overexpression of p21 results in suppression of tumor growth in vitro and in vivo.Unfortunately, p21 protein alone is unable to be administered directly in vivo and progress to the cell nuclei of cancer cells since there is no active mechanism to transport the protein. However, a number of proteins are known which can translocate across the cytoplasmic membrane of mammalian cells and into the nuclei, carrying additional cargoes with them. One of these translocating proteins is a 60 amino acid peptide corresponding to the homeodomain of the Drosophilia protein Antennapedia [ANTP].

A fusion protein (TR1) has been developed where the full-length p21 protein is attached to the antennapedia protein with a view to delivering the p21 protein into cancer cells to restore cell cycle control.

TR1 penetrated and killed cancer cells that do not express wild type p53 or p21. This included cells that were matched to cogenic parental cell lines. Antp-p21 killed cancer cells selectively that were malignant as a result of mutations or nuclear exclusion of the p53 and p21 genes and over-expression of MDM2.Non-specific toxicity was excluded by showing that TR1 penetrated but did not kill p53- or p21- wild-type cells. TR1 was not immunogenic in normal New Zealand White rabbits. Recombinant Antp peptide alone was not cytotoxic, showing that killing was due to the transduction of the p21 component of TR1. TR1was shown to penetrate cancer cells engrafted in vivo and resulted in tumour eradication when administered with chemotherapy.

TR1 may represent a new and promising targeted therapy for patients with p53-associated cancers supporting the concept that rational design of therapies directed against specific cancer mutations will play a part in the future of cancer therapeutics.

Citation Format: Agamemnon A. Epenetos, Christina Kousparou, Aleksandra Filipovic. Generation of a selectively cytotoxic fusion protein against p53 mutated cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2987.
Abstract 3021: Development of small molecule direct AMPK activators for the treatment of cancer
Authors: Hitoshi Yasumichi , Jenkins Yonchu , Li Yingwu , Sampang Elmer , Xu Xiang , Dong Guodong , Huang Jianing , Lin Nan , Goff Dane , Shaw Simon , Boralsky Luke , Singh Rajinder , Issakani Sarkiz D. , Payan Donald G.
Published: July 2016

5’-AMP-activated protein kinase (AMPK) is a key sensor of cellular energy status and is critical for maintaining energy homeostasis under conditions of nutrient stress. During cellular transformation, metabolic reprogramming enables the aberrant growth and proliferation of tumor cells. Both positive and negative roles for AMPK in tumor cell proliferation and survival have been reported. However, only a limited number of studies addressed this question with potent direct AMPK activators. AMPK exists as heterotrimers composed of the catalytic subunit α and reguratory subunits β and γ. We expressed the full length of all three human AMPK subunits in insect cells, purified the heterotrimer complexes, and used them for biochemical screening and characterization of AMPK activators. The purified complexes displayed basal activity, which was further enhanced by AMP. The compounds we identified potently activated the complexes in vitro at AC(2X)s (the concentration that gives a twofold activation) of 0.001-0.3 μM. Importantly, the compounds up-regulated substrate phosphorylation (pS79 Acetyl-CoA Carboxylase) and/or auto-phosphorylation (pT172 AMPKα) in multiple cancer cell lines including HepG2 hepatoma cells, A549 liver kinase B1 (LKB1) null lung cancer cells, and MOLM14 myeloid leukemia cells, indicating activation was irrespective of functional status of LKB1, which is a key AMPK-activation kinase. Activation of AMPK by the compounds was also confirmed using native AMPK isolated from normal tissues and tumor cells. We further investigated anti-proliferative effects of the compounds and found that up-regulation of AMPK kinase activity was correlated with anti-proliferative effects in A549 and MOLM14, but not in HepG2, suggesting that positive effects of direct AMPK activators could be cell-type dependent. Interestingly, we identified compounds that display comparable AMPK activation in HepG2 and A549 yet possessed divergent activities on proliferation across a panel of tumor lines. Analysis of cellular signaling across several of these tumor lines with this set of the compounds revealed dose-dependent effects on mTORC1 substrates, feedback signaling to PI3K and mTORC2, and inhibition of kinases downstream of RAF. Direct activation of AMPK could be a good therapeutic strategy for the treatment of subsets of cancers.

Citation Format: Yasumichi Hitoshi, Yonchu Jenkins, Yingwu Li, Elmer Sampang, Xiang Xu, Guodong Dong, Jianing Huang, Nan Lin, Dane Goff, Simon Shaw, Luke Boralsky, Rajinder Singh, Sarkiz D. Issakani, Donald G. Payan. Development of small molecule direct AMPK activators for the treatment of cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3021.
Abstract 3032: A novel compound ARN-3236 inhibits SIK2 and sensitizes ovarian cancer to paclitaxel
Authors: Zhou Jinhua , Alfredi Albandri , Zhang Shu , Santiago-O’Farrill Janice M. , Ahmed Ahmed A. , Yang Hailing , Mao Weiqun , Wang Yan , Vankayalapati Hariprasad , Lu Zhen , Bast Robert C.
Published: July 2016

Ovarian carcinomas account for 4% of total cancers in women in the United States. Improved outcomes might be attained if sensitivity to primary chemotherapy were enhanced. A recent study discovered that the salt inducible kinase 2 (SIK2) plays a key role in the initiation of mitosis and regulates paclitaxel sensitivity. Here we show that SIK2 is overexpressed in 30% ovarian cancer specimens, associated with a poor prognosis. ARN-3236, a selective, highly potent small molecule SIK2 inhibitor with function similar to SIK2 siRNA, blocks cell proliferation in a panel of ovarian cancer cell lines, where the IC50 of ARN-3236 was inversely correlated with endogenous SIK2 expression. ARN-3236 also enhanced response to paclitaxel in ovarian cancer cells (OC316, SKOv3, A2780, HEY, ES2 and UPN251). Similar to the function of SIK2 siRNA, ARN-3236 effectively inhibits AKT phosphorylation at Ser473 and Tyr308, as well as the expression of the downstream effector survivin. ARN-3236 uncouples the centrosome from the nucleus in interphase, and blocks centrosome separation in mitosis, resulting in the accumulation of cells in prometaphase. In addition, ARN-3236 enhances tumor growth inhibition of paclitaxel in ovarian cancer xenograft models. Thus, functional inhibition of SIK2 with ARN-3236 had the same effects on ovarian cancer cell function as knockdown of SIK2 with siRNA. ARN-3236 deserves further study as a SIK2 inhibitor that significantly improves the sensitivity to paclitaxel for treatment of human ovarian cancer cells and xenografts.

Citation Format: Jinhua Zhou, Albandri Alfredi, Shu Zhang, Janice M. Santiago-O’Farrill, Ahmed A. Ahmed, Hailing Yang, Weiqun Mao, Yan Wang, Hariprasad Vankayalapati, Zhen Lu, Robert C. Bast Jr. A novel compound ARN-3236 inhibits SIK2 and sensitizes ovarian cancer to paclitaxel. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3032.
Abstract 3043: Survivin-mediated radio-sensitization response in p53 mutant tumor cells
Authors: Grdina David J. , Murley Jeffrey S. , Miller Richard C. , Weichselbaum Ralph R. , Rademaker Alfred W. , Woloschak Gayle E. , Li Jian Jian
Published: July 2016

Doses of ionizing radiation ≤100 mGy induce changes in radiation sensitivity expressed by cells exposed to subsequent higher doses. This is referred to as an adaptive effect. We describe a unique survivin-associated adaptive response in which increased radiation resistance or sensitization of cells can be induced by exposure to doses as low as 5 mGy. Experiments were performed using two murine sarcomas, SA-NH and FSa,grown either in culture or as tumors, and two human cancer cell lines, Panc-1 (pancreatic epithelioid carcinoma) and MDA-MB-231 (breast adenocarcinoma). Doses of 5 mGy were used to induce changes in the response of these tumor cells to higher therapy doses using a multi-dosing paradigm. Effects on radiation sensitivity were associated with changes in both survivin concentration and its translocation to the cytoplasm (SA-NH, p53 wild type) or nucleus (FSa, Panc-1 and MDA-MB-231, p53 mutant). In vitro survival assays (2 Gy per fraction, two once daily fractions) and tumor growth delay (TGD) (5 Gy per fraction, five once daily fractions) studies were performed on SA-NH and FSa cells. Intracellular localization of survivin was determined by ELISA and correlated to survival response. 2 Gy alone had no effect on intracellular translocation of survivin. When preceded 15 min earlier by a 5 mGy exposure, survivin increased in the cytoplasm of SA-NH as compared to the nuclei of FSa, Panc-1 and MDA-MB-231 cells. SA-NH tumors were protected by 5 mGy exposures (1.9 day decrease in TGD, P = 0.032) while FSa tumors were sensitized (4.5 day increase in

TGD, P < 0.001). Panc-1 and MDA-MB-231 tumor cells were also sensitized to ionizing radiation following 5 mGy exposures. Exposure of SA-NH to 4 mM of the free radical scavenger N-acetylcysteine inhibited the effect of 5 mGy on inducing this adaptive response. We have identified a very low radiation dose-induced survivin-mediated radio-sensitization response that could enhance therapeutic outcomes associated with the increased usage of imaging procedures in radiation therapy. This work was supported by NIH/NCI grant R01 CA132998 and DOE Low Dose Program/Project Grant DE-SC0001271 (D.J.G.)

Citation Format: David J. Grdina, Jeffrey S. Murley, Richard C. Miller, Ralph R. Weichselbaum, Alfred W. Rademaker, Gayle E. Woloschak, Jian Jian Li. Survivin-mediated radio-sensitization response in p53 mutant tumor cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3043.
Abstract 3056: Combined disulfiram and radiation therapy against atypical teratoid/rhabdoid tumor
Authors: Lee Yeoung Eun , Choi Seung Ah , Kwak Pil Ae , Wang Kyu-Chang , Phi Ji Hoon , Lee Ji Yeoun , Chong Sangjoon , Moon Youn Joo , Jangra Anshika , Joo Kyeung Min , Kim Seung-Ki
Published: July 2016

Disulfiram (DSF) has been studied as an anticancer drug and radiosensitizer. In our previous study, the therapeutic potential of DSF against atypical teratoid/rhabdoid tumor (AT/RT), one of the most aggressive forms of childhood cancer, had been confirmed using in vitro and in vivo studies. To develop more effective and safer therapy in AT/RT, we evaluated the sensitizing potential of DSF on radiation therapy (RT). The effect of DSF in low concentration alone and in combination with RT was investigated in vitro and vivo. Clonogenic assay, western blot analysis, autophagy assay and γ-H2AX foci staining were performed using several primary cultured AT/RT cells and cell lines. Also, in vivo study was performed using AT/RT orthotopic xenograft mouse model. Combination therapy with DSF and RT potently reduced clonogenicity and down-regulated protein expression of survivin and BCL2. The combination treatment strongly promoted the autophagic cell death and produced abundant γ-H2AX foci in all AT/RT cells. Moreover, the combination treatment significantly reduced the tumor growth and prolonged the survival rate compared to single treatment in AT/RT mouse model. Taken together, our results demonstrated that the combination therapy with DSF and RT has a synergistic therapeutic effect on AT/RT, suggesting a potential clinical application for AT/RT patients.

Citation Format: Yeoung Eun Lee, Seung Ah Choi, Pil Ae Kwak, Kyu-Chang Wang, Ji Hoon Phi, Ji Yeoun Lee, Sangjoon Chong, Youn Joo Moon, Anshika Jangra, Kyeung Min Joo, Seung-Ki Kim. Combined disulfiram and radiation therapy against atypical teratoid/rhabdoid tumor. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3056.
Abstract 3061: AS-10: a new small molecule with promising activity against pancreatic cancer
Authors: Karelia Deepkamal , Pandey Manoj K. , Plano Daniel , Amin Shantu , Sharma Arun K.
Published: July 2016

Patients with pancreatic cancer (PC) have a median survival of only 6 months and a five-year survival of less than 5%, hence making PC one of the deadliest cancer. Severity of PC is due to its identification at late stages, rapid local invasion, early metastases, and meager response to current chemotherapeutic agents. Current therapies result in minimal survival advantage and are linked with multiple adverse events and drug resistance. Hence, there is an urgent need for novel agents which are less toxic and offer greater benefits over conventional therapy. There is ample evidences in literature demonstrating that inflammation plays a critical role in PC growth and promotion. Nuclear factor κB (NF-κB) pathway, one of the major inflammatory pathway, is well known for its inflammatory response, cell proliferation, and resistance to apoptosis. It has been demonstrated that activation of NF-κB in PC is also responsible for resistance towards first line chemotherapeutic agent, gemcitabine, in PC. Through extensive structure-activity relationship studies, we have recently identified a novel small molecule, AS-10, which was lethal to PC cells. We sought to evaluate the mechanism of action of AS-10 responsible for inhibiting the growth of PC cells. In vitro, AS-10 reduced PC cell growth with an EC50, in the range of 2.5 to 5 μM. Growth arrest was confirmed by cell cycle studies, which showed that AS-10 induced G1 and G2 cell cycle arrest. The cell cycle arrest was associated with an increase of cell cycle inhibitory markers like p21 and p27. Effect of AS-10 on cell cycle was translated into activation of apoptosis, confirmed by caspase 3/7 activity, PARP cleavage and Annexin V staining. Due to its structural characteristics, we evaluated the effect of AS-10 on inflammatory NF-κB pathway. Our studies, in Panc-1 cells, showed that AS-10 inhibited NF-κB DNA binding activity as well as NF-κB translocation to the nuclei in the presence of inflammatory stimuli (tumor necrosis factor (TNFα)). Since, up regulation of NF-κB activity has been known to be responsible for gemcitabine resistance in PC, we evaluated the activity of our NF-κB inhibitor AS-10 in combination with gemcitabine, and showed that AS-10 synergistically potentiated gemcitabine activity in PC cells. Taken together, these results suggest that AS-10, may represent a potentially promising therapeutic agent for PC. Detailed investigations regarding the efficacy and mechanism of action of these compounds will be presented.

Citation Format: Deepkamal Karelia, Manoj K. Pandey, Daniel Plano, Shantu Amin, Arun K. Sharma. AS-10: a new small molecule with promising activity against pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3061.
Abstract 3062: Silencing the epigenetic silencer KDM4A for TRAIL and DR5 simultaneous induction and antitumor therapy
Authors: Wang Junjian , Wang Haibin , Wang Lingyu , Cai Demin , Duan Zhijian , Chen Peng , Zou June X , Xu Jianzhen , Chen Xinbin , Kung Hsing-Jien , Chen Hong-wu
Published: July 2016

Recombinant TRAIL and agonistic antibodies to death receptors (DRs) have been in clinical trial but displayed limited anti-cancer efficacy. Lack of functional DR expression in tumors is a major limiting factor. We report here that chromatin regulator KDM4A/JMJD2A, not KDM4B, plays a pivotal role in silencing tumor cell expression of both TRAIL and its receptor DR5. In TRAIL-sensitive and -resistant cancer cells of lung, breast and prostate, KDM4A small-molecule inhibitor compound 4 (C-4) or genetic silencing strongly induces TRAIL and DR5 expression, and causes TRAIL-dependent apoptotic cell death. KDM4A inhibition also strongly sensitizes cells to TRAIL. C-4 alone potently inhibits tumor growth with marked induction of TRAIL and DR5 expression in the treated tumors and effectively sensitizes them to the newly developed TRAIL-inducer therapeutics ONC201. Mechanistically, C-4 does not appear to act through the Akt-ERK-FOXO3a pathway. Instead, it switches histone modifying enzyme complexes at TRAIL and DR5 transcriptional activator CHOP gene promoters by dissociating KDM4A and NCoR-HDAC corepressor complex, and inducing the recruitment of histone acetylase CBP. Thus, our results reveal KDM4A as a key epigenetic silencer of TRAIL and DR5 in tumors and establish inhibitors of KDM4A as a novel strategy for effectively sensitizing tumors to TRAIL pathway-based therapeutics.

Citation Format: Junjian Wang, Haibin Wang, Lingyu Wang, Demin Cai, Zhijian Duan, Peng Chen, June X Zou, Jianzhen Xu, Xinbin Chen, Hsing-Jien Kung, Hong-wu Chen. Silencing the epigenetic silencer KDM4A for TRAIL and DR5 simultaneous induction and antitumor therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3062.
Abstract 3070: Potent and selective inhibition of CDK7 by novel covalent inhibitors
Authors: Satyam Leena Khare , Poddutoori Ramulu , Mukherjee Subhendu , Marappan Sivapriya , Gopinath Sreevalsam , Ramachandra Raghuveer , Pothuganti Manoj Kumar , Nayak Shilpa S. , C Nandish , Naik Chandranath , MV Ravindra , Dabbeeru Madhu B. , A Nagaraju , B Mahankali , Antony Thomas , Pandit Chetan , Chelur Shekar , Daginakatte Girish , Samajdar Susanta , Ramachandra Murali
Published: July 2016

Background: Phosphorylation of the RNA polymerase II (RNAPII) in C-terminal domain (CTD) by Cyclin-dependent kinase 7 (CDK7) is an important step in cellular transcription process. Hence pharmacological modulation of CDK7 kinase activity is considered as an interesting approach to treat cancers that critically dependent on transcription to maintain their oncogenic state.

Experimental procedures: Multiple series of novel covalent CDK7 inhibitors were identified by SBDD approach based on the binding mode of known CDK7 inhibitors to find early hits. Iterative medicinal chemistry efforts were performed to identify several lead compounds by optimizing the initial hits to achieve good physicochemical properties, high potency, good selectivity and desirable pharmacokinetic profile.

Summary: Highly potent ATP competitive covalent inhibitors of CDK7 from two distinct chemical series were identified. They show time-dependent inhibition of CDK7 enzyme activity as a proof of covalent binding and exhibit potent anti-proliferative activity in cell lines derived from various tumor types. CDK7 modulation by these compounds was also confirmed by monitoring cellular pS5RNAPII levels. Representative compounds from each series showed very good selectivity profile in broad kinase (332) panel. Lead molecules were identified based on excellent drug-like properties (solubility, permeability and good oral bioavailability). Tolerability and efficacy studies in rodent xenograft models are ongoing with selected leads to test their impact on tumor growth inhibition and to determine therapeutic window by oral administration.

Conclusion: We have identified novel and selective CDK7 covalent inhibitors from two distinct chemical series with optimized drug-like properties including oral bioavailability. These compounds are being evaluated

for anti-tumor activity in mouse xenograft models.

Citation Format: Leena Khare Satyam, Ramulu Poddutoori, Subhendu Mukherjee, Sivapriya Marappan, Sreevalsam Gopinath, Raghuveer Ramachandra, Manoj Kumar Pothuganti, Shilpa S. Nayak, Nandish C, Chandranath Naik, Ravindra MV, Madhu B. Dabbeeru, Nagaraju A, Mahankali B, Thomas Antony, Chetan Pandit, Shekar Chelur, Girish Daginakatte, Susanta Samajdar, Murali Ramachandra. Potent and selective inhibition of CDK7 by novel covalent inhibitors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3070.
Abstract 3073: Targeting chronic lymphocytic leukemia by interfering glutathione synthesis using a novel therapeutic enzyme cyst(e)inase (AEB3103)
Authors: Liu Jinyun , Feng Li , Stone Everett M. , Tyler Joseph , Rowlinson Scott W. , Keating Michael J. , Huang Peng
Published: July 2016

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the Western countries. Despite recent advance in new therapeutic agents that have improved treatment outcomes, CLL remains incurable due in part to the inability to completely eradicate the leukemia cells in vivo. Previous studies showed that CLL cells have high intrinsic oxidative stress and are highly dependent on cellular antioxidant glutathione (GSH) to maintain redox balance and cell viability. One logical strategy to impact CLL cells would be to abrogate the glutathione protection of CLL cells in vivo. Recently we discovered that primary leukemia cells isolated from CLL patients were unable to effectively utilize cystine for GSH synthesis due to low expression of the cystine transporter Xc-, and that bone marrow stromal cells highly express Xc- and effectively take up cystine for conversion to cysteine (Zhang et al: Nature Cell Biology, 2012). These findings provide a biochemical basis to develop novel strategies to effectively target leukemia cells in the stromal microenvironment and improve in vivo therapeutic activity. In this study, we tested the depletion of extracellular cystine and cysteine using a novel therapeutic enzyme-cyst(e)inase (AEB3103), as a potential way to block GSH synthesis in CLL cells and abolish the stromal protection of the leukemia cells. Our study showed that AEB3103 was very effective in depleting GSH in CLL cells and caused massive CLL cell death even in the presence of stromal cells. Importantly, AEB3103 could also overcome drug resistance of CLL cells with p53 deficiency both in primary leukemia cells isolated from CLL patients with 17p deletion and mouse leukemic cells isolated from mouse model we recently reported (Liu et al: Leukemia, 2014). In addition, AEB3103 showed very low toxicity to normal cells. These promising in vitro data warrant further animal studies, which are currently on ongoing using the CLL mouse model with TCL1-Tg:p53-/- genotype. Our study suggests that AEB3103 and its combination with standard anti-CLL drugs may potentially be useful for clinical treatment of CLL, even for the more aggressive CLL subtypes with unfavorable cytogenetic alterations such as those with chromosome17p deletion and p53 mutations, and may improve in vivo therapeutic activity.

Citation Format: Jinyun Liu, Li Feng, Everett M. Stone, Joseph Tyler, Scott W. Rowlinson, Michael J. Keating, Peng Huang. Targeting chronic lymphocytic leukemia by interfering glutathione synthesis using a novel therapeutic enzyme cyst(e)inase (AEB3103). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3073.
Abstract 3081: Novel cucurbitacin analogue Cuc D exhibits potent anti-cancer activity in cervical cancer
Authors: Sikander Mohammed , Hafeez Bilal Bin , Halaweish Fathi T. , Yallapu Murali M. , Jaggi Meena , Chauhan Subhash C.
Published: July 2016

Background: Cervical cancer is one of the leading cause of mortality among women in US. Naturally occurring dietary compounds have gained increasing attention for their anticancer effects. Cucurbitacins, tetracyclic triterpenoid compound, belong to a family of Cucurbitaceae have shown promising anti-cancer activity. Herein, we investigated the potential anti-cancer effects of a novel analogue of cucurbitacin D (Cuc D) against cervical cancer in in vitro and in a xenograft mouse model.

Methods: In our study, we used human cervical cancer cells (CaSki and SiHa). Cells were treated with Cuc D (0.05 to 1μM) for 48 and 72 hrs. MTS and colony formation assays were performed to investigate the effects of Cuc D on cell viability and proliferation. Western Blot analysis was performed to investigate the effects of Cuc D on cell proliferation and apoptotic markers. To determine the therapeutic effects of Cuc D, we used female athymic nude mice and injected CaSki cells (4 × 106) into the cervix to develop orthotopic xenograft tumors. Cuc D (1 mg/kg body weight) was administered through intratumoral injection four weeks post-tumor cell injection. Tumor volume in these mice were recorded bi-weekly.

Results: Cuc D inhibited cell viability of cervical cancer cells in a dose-dependent manner. IC50 of Cuc D was observed 400 nM and 250 nM in Caski and SiHa cells, respectively. Cuc D treatment effectively inhibited growth of cervical cancer cells which was determined by decreased cell proliferation and colony formation assays. Cuc D treatment induced apoptosis in cervical cancer cells as measured by enhanced Annexin V staining. Western blot result also illustrated cleavage in PARP protein in Cuc D treated cells which further confirms apoptosis induction. Cuc D treatment also inhibited PI3K and c-Myc protein levels and phosphorylation of STAT3 and Rb proteins. In addition, Cuc D treatment induced the cell cycle inhibitory proteins (p21 and p27) and PTEN and the expression of a tumor suppressor microRNA, miR-145, as determined by qRT-PCR. In an orthotopic tumor xenograft mouse model, Cuc D treatment effectively inhibited tumor growth as compared to vehicle control treated mice.

Conclusion: Taken together, our results demonstrate potent anti-cancer efficacy of Cuc D in cervical cancer cells via modulation of key onco/tumor suppressor proteins. Thus, Cuc D could be a useful therapeutic agent for cervical cancer treatment.

Citation Format: Mohammed Sikander, Bilal Bin Hafeez, Fathi T. Halaweish, Murali M. Yallapu, Meena Jaggi, Subhash C. Chauhan. Novel cucurbitacin analogue Cuc D exhibits potent anti-cancer activity in cervical cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3081.