bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract C246: SH-4-54, a novel small-molecule inhibitor of STAT3, demonstrates significant anti-tumor activity against multiple myeloma.
Authors: Li Zhi Hua , Haftchenary Sina , Croucher Danielle , Gunning Patrick T. , Trudel Suzanne
Published: August 2014

Aberrant STAT3 signaling is prevalent in hematologic malignancies such as Multiple Myeloma (MM) and is recognized as a master regulator of tumor processes such as survival, angiogenesis, and drug resistance. Significant efforts have therefore focused on therapeutic targeting of STAT3 as an anti-cancer strategy. Based on rational structure-based design, we present pre-clinical findings for a newly developed small molecule STAT3 inhibitor, SH-4-54. SH-4-54 was designed to block the SH2 domain of STAT3 by mimicking its native phosphopeptide binding sequence and in turn prevent phosphorylation (activation) and disrupt transcriptionally active STAT3:STAT3 dimerization. SH-4-54 has been shown to have a KD for STAT3 protein of 300 nM by surface plasmon resonance and inhibits STAT3 SH2 domain-phosphopeptide interactions as assessed by a fluorescence polarization assay.

The anti-MM activity of SH-4-54 was assessed using MTT assays against a panel of molecularly heterogeneous human myeloma cell lines (HMCLs), revealing potent and broad effects on cell viability with 10/15 HMCLs displaying IC50 values < 10 μM. Moreover, SH-4-54 induced apoptotic responses in HMCLs as evidenced by increased Annexin V staining. Promising results were observed for the effects of SH-4-54 on primary patient-derived myeloma cells. Using flow cytometric analysis of CD138 as a marker of myeloma cells and Annexin V staining, SH-4-54 was found to significantly reduce the percentage of CD138+/Annexin V negative, viable myeloma cells, while displaying little to no toxicity against the non-malignant (CD138−) cell fraction. Supporting the predicted molecular mechanisms of SH-4-54 activity, immunoblot analysis revealed that SH-4-54 inhibits constitutive STAT3 phosphorylation, but does not alter STAT3 protein levels. Furthermore, using HMCLs engineered to express a STAT3-driven luciferase reporter construct, SH-4-54 was found to significantly reduce STAT3 transcriptional activity, and consistently induce a reduction in proteins that encode STAT3 target genes such as c-Myc.

Taken together, our results highlight the promising therapeutic potential of SH-4-54 and support the continued development of targeted therapies for MM with a focus on aberrant STAT signaling.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C246.

Citation Format: Zhi Hua Li, Sina Haftchenary, Danielle Croucher, Patrick T. Gunning, Suzanne Trudel. SH-4-54, a novel small-molecule inhibitor of STAT3, demonstrates significant anti-tumor activity against multiple myeloma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C246.
Abstract C291: Targeting SDF-1 (CXCL12) pathway to inhibit the recurrence of breast cancer brain metastases after whole-brain irradiation.
Authors: Chernikova Sophia , Ahn G-One , Liu Shie-Chau , Stafford Jason , Brown J. Martin
Published: August 2014

The presence of tumor-associated macrophages (TAMs) in tumors strongly correlates with poor outcome. At least one lineage of TAMs originates from the peripheral bone marrow-derived mononuclear cells. We have previously reported that bone marrow-derived CD11b+ myeloid cells contribute to tumor regrowth after irradiation by homing to the irradiated site, where they aid in restoring tumor vasculature. We have also shown that inhibiting the recruitment of CD11b+ monocytes/macrophages by blocking the SDF-1 (CXCL12)-CXCR4 axis prevents or delays recurrence of mouse and rat glioblastoma after irradiation. We further demonstrate that TAMs in the irradiated glioblastoma could be detected in vivo by magnetic resonance (MR) imaging of iron oxide nanoparticles phagocytosed by TAMs. Radiation remains one of the major modalities for treatment of breast cancer brain metastases (BCBMs). We hypothesized that inhibition of SDF-1 mediated neovasculogenesis may be as useful for treatment of BCBMs as it is for treatment of glioblastoma. In this study, brain metastases from MDA-MB-231-BR3 cells injected through intra-carotid artery in nude mice were detected by bioluminescence imaging. SDF-1 activity was inhibited using Spiegelmer NOX-A12. Treatment with NOX-A12 began immediately after irradiation, and continued every second day until the end of the experiment. We show that combination of NOX-A12 with 12Gy resulted in marked delay of metastatic regrowth after irradiation compared to 12Gy alone and a doubling of the survival time of the mice. Detection of TAMs using MR imaging of iron oxide nanoparticles is under way.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C291.

Citation Format: Sophia Chernikova, G-One Ahn, Shie-Chau Liu, Jason Stafford, J. Martin Brown. Targeting SDF-1 (CXCL12) pathway to inhibit the recurrence of breast cancer brain metastases after whole-brain irradiation. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C291.
Abstract CN01-03: Prospects for miRNA- and lncRNA-based cancer therapeutics.
Authors: Agami Reuven
Published: August 2014

The past decade has witnessed a swift advance in the identification of microRNAs and elucidation of their function. In particular, miRNAs were found to present cancer-specific expression patterns, but also to encompass causative roles in cancer development and in resistance to therapy. This fundamental biological research has led to the initiation of clinical trials testing oligonucleotide-based therapies inhibiting or mimicking microRNAs. With their simple design, scalability, and systemic delivery to the body, oligonucleotide-based therapy seems easier and faster to develop, improve, and put to practice than gene and drug-based therapies. The outcome of ongoing clinical trials will determine how valuable microRNAs are as therapeutic targets.

In contrast to microRNAs, the research field of the long noncoding RNA (lncRNA) is only starting to emerge. Their recent identification, long size, typical low expression level, and excessive structure delayed progress. Principally, lncRNAs can be divided into two types; those that are spliced and polyadenylated and therefore are relatively more stable, and those that are not, and thus are very labile. While the first group may have trans and cis functions, the second mostly exert a local activity on the chromatin of neighboring genes. I will present principle examples related to the tumor suppressor p53 pathway in humans. Altogether, it appears that lncRNAs can be as powerful as microRNAs in controlling essential cellular processes. However, a dedicated preclinical investigation of lncRNAs is required to characterize and understand how they function in order to discover the best ways to control their function. Only when such pronounced fundamental understanding is achieved can we start implementing lncRNAs in therapy.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):CN01-03.

Citation Format: Reuven Agami. Prospects for miRNA- and lncRNA-based cancer therapeutics. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr CN01-03.
Abstract CN06-04: Reversible tolerance to anticancer drugs.
Authors: Settleman Jeffrey E.
Published: August 2014

A variety of pathway-targeted inhibitors have recently proven to provide significant clinical benefit to genotype-defined subsets of cancer patients. However, these agents are not curative due to the relatively rapid acquisition of drug resistance in virtually all cases. In some patients, specific mutational mechanisms of acquired drug resistance have been identified, prompting the discovery and development of second-generation therapeutics that can overcome these resistance mechanisms. In addition to such genetic resistance mechanisms, our preclinical modeling studies of acquired drug resistance have revealed the heterogeneous nature of "clonal" tumor-derived cell lines, and the existence of subpopulations of cells with distinct vulnerabilities to treatments that effectively kill the vast majority of cells in the population. This seemingly stochastic spontaneous acquisition of distinct phenotypes within cancer cell populations is reversible, and therefore non-genetic in nature. We find that this stochastic switch is associated with distinct chromatin states, and that cells exhibiting the drug "tolerant" state display sensitivities to a variety of agents that are largely ineffective against the bulk population of cells. We have also found evidence that the drug-tolerant switch is analogous to the epithelial-mesenchymal transition, which is also spontaneously reversible and associated with distinct drug sensitivities. These findings highlight the dynamic nature of clonal heterogeneity within cancer cell populations and point to a likely need to co-target multiple distinct cellular states within a tumor population to effectively eradicate cancer cells and minimize the likelihood of acquired drug resistance and tumor recurrence.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):CN06-04.

Citation Format: Jeffrey E. Settleman. Reversible tolerance to anticancer drugs. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr CN06-04.
Abstract PL01-01: Using synthetic lethality to find effective combination therapies for cancer.
Authors: Bernards René
Published: August 2014

Cancer remains difficult to treat, even with the new generation of targeted cancer drugs. By far the most formidable obstacle is the rapid emergence of therapy resistance. Indeed, many of the new cancer drugs elicit powerful initial responses, leading to dramatic effects on "progression free survival," but far less long-term benefit is seen in terms of overall survival. Combination therapies can help fight therapy resistance, but with an arsenal of over 1000 cancer drugs in clinical development, the number of possible combinations seems nearly endless. In my laboratory we employ functional genetic screens to find powerful combinations of cancer drugs by exploiting the concept of "synthetic lethality." Using RNA interference-based genetic screens with collections of shRNAs that target druggable gene families, we search for genes whose inactivation is particularly synergistic with clinically-relevant cancer drugs. Such screens can identify drug combinations that are far more powerful than the sum of the two single agents. We aim to understand the molecular rationale for the observed synergy between two cancer drugs. Once we have insight into the molecular mechanism, we aim to bring such rationally-designed combinations to the cancer clinic as soon as possible through our clinical collaborations in our comprehensive cancer center. As a second approach, we use genome wide loss-of-function genetic screens in cancer cells that are sensitive to the drug-of-interest to search for genes whose down-regulation confers resistance to the drug-of-interest. Such genetic screens can identify novel mechanisms of drug resistance. This in turn may suggest strategies that help prevent drug resistance. Examples of genetic screens that help to optimize the treatment of cancer will be presented.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL01-01.

Citation Format: René Bernards. Using synthetic lethality to find effective combination therapies for cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL01-01.
Abstract PL02-02: The genetic basis of kidney cancer: A metabolic disease.
Authors: Linehan W. Marston
Published: August 2014

Much of what is known about the genetic basis of kidney cancer has been learned from the study of inherited forms of kidney cancer, including von Hippel-Lindau (VHL) (clear cell kidney cancer, the VHL gene), hereditary papillary renal carcinoma (type 1 papillary kidney cancer, the MET gene), Birt-Hogg-Dubé (BHD) (chromophobe kidney cancer, the FLCN gene), hereditary leiomyomatosis and renal cell carcinoma (HLRCC, the fumarate hydratase gene), and SDH-RCC (the succinate dehydrogenase genes). Study of these disease gene pathways has shown that kidney cancer is fundamentally a metabolic disease. Each of the known kidney cancer genes affects the cell's ability to sense changes in oxygen, iron, nutrients or ATP. This is most clearly illustrated in fumarate hydratase (FH) and succinate dehydrogenase (SDH) deficient kidney cancer. FH-deficient kidney cancer, an extremely aggressive form of type 2 papillary kidney cancer, is characterized by a metabolic shift to aerobic glycolysis and impaired oxidative phosphorylaton, decreased AMPK, fumarate-induced impairment of dioxygenases (such as prolyl hydroxylase), resulting in increased stability of HIF and DNA and histone methylation, glutamine dependent reductive carboxylation and a fumarate-mediated activation of the Nrf2 pathway. SDH-deficient kidney cancer is characterized by a metabolic shift to aerobic glycolysis, a profound impairment of oxidative phosphorylation and a glutamine-dependent reductive carboxylation pathway for lipid biosynthesis. Clinical trials are currently underway targeting the metabolic basis of FH-deficient kidney cancer.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL02-02.

Citation Format: W. Marston Linehan. The genetic basis of kidney cancer: A metabolic disease. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL02-02.
Abstract PL02-03: Ras-induced macropinocytosis: Metabolic adaptation to signaling in the absence of adequate nutrients.
Authors: Thompson Craig B.
Published: August 2014

Under conditions of an abundant supply of extracellular glucose and glutamine, cancer cells synthesize lipids, nucleic acids, and non-essential amino acids from these precursors. However, when cancer grows to exceed its vascular supply, cells must adapt to lower availability of essential nutrients and oxygen. This past year we have seen a significant breakthrough in the discovery of novel mechanisms by which cancer cells adapt to metabolic stress. It was previously determined that glutamine-dependent lipid synthesis could support de novo lipid synthesis under hypoxia but metabolic tracing studies uncovered that over 50% of lipids used in phospholipid biosynthesis in hypoxic cells come from exogenous sources. We were able to determine that hypoxia-induced macropinocytosis facilitates the uptake and incorporation of unsaturated phospholipids to maintain effective unsaturated lipid levels under conditions in which stearoyl-CoA desaturase is inhibited by oxygen limitation. Follow up studies, in collaboration with others, have demonstrated that this property of cellular scavenging of extracellular macromolecules is induced in a Ras-dependent fashion in transformed cells and provides a potent mechanism by which Ras-transformed cells can adapt to metabolic stress in their environment. How these insights can be used to develop novel therapeutic strategies to address Ras-induced tumors will be discussed.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL02-03.

Citation Format: Craig B. Thompson. Ras-induced macropinocytosis: Metabolic adaptation to signaling in the absence of adequate nutrients. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL02-03.
Abstract PL02-04: IDH mutations and tumorigenicity.
Authors: Wang F. , Travins J. , DeLaBarre B. , Penard-Lacronique V. , Schalm S. , Hansen E. , Straley K. , Kernytsky A. , Liu W. , Gliser C. , Yang H. , Gross S. , Artin E. , Saada V , Mylonas E. , Quivoron C. , Popovici-Muller J. , Saunders J. O. , Salituro F. G. , Yan S. , Murray S. , Wei W. , Gao Y. , Dang L. , Dorsch M. , Agresta S. , Schenkein D. P. , Biller S. A. , Su S. M. , Botton S. de , Yen Katharine E.
Published: August 2014

Mutations in the isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes are present in ∼20% of acute myeloid leukemia, and cause a neomorphic enzyme activity that results in the production of 2-hydroxyglutarate (2HG). Mutational and epigenetic profiling of a large patient cohort of acute myeloid leukemia (AML) has revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and impaired hematopoietic differentiation.

To further investigate the intrinsic effect of 2HG on hematopoietic proliferation and differentiation, we transfected an erythroleukemia cell line (TF-1) with either IDH1 or IDH2 mutant alleles. These cells overexpress the mutant enzyme, have high levels of 2HG, and exhibit GM-CSF independent growth. Consistent with clinical observations, overexpression of the IDH mutant proteins led to hypermethylation of both histones and DNA. These results suggest that mutations in IDH1/2 could lead to epigenetic rewiring of cells that could facilitate the gain of function phenotype. We are currently studying the global and specific effects of IDH1/2 mutant overexpression to gain a broader understanding of the biological consequence of the IDH1/2 gain of function mutations.

We have also generated mutation selective molecules that are capable of inhibiting IDHm enzymes. Upon compound treatment in vitro, we are able to reverse hypermethylation of both histones and DNA and induce cellular differentiation in IDHm cell lines and primary human IDHm AML patient samples(1, 2). These data suggest that an inhibitor of IDH1/2 mutations could correct the altered gene expression patterns seen in IDH1/2 mutant AML tumors leading to a profound effect on hematopoietic differentiation, proliferation and tumor growth.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL02-04.

Citation Format: F. Wang, J. Travins, B. DeLaBarre, V. Penard-Lacronique, S. Schalm, E. Hansen, K. Straley, A. Kernytsky, W. Liu, C. Gliser, H. Yang, S. Gross, E. Artin, V Saada, E. Mylonas, C. Quivoron, J. Popovici-Muller, J. O. Saunders, F. G. Salituro, S. Yan, S. Murray, W. Wei, Y. Gao, L. Dang, M. Dorsch, S. Agresta, D. P. Schenkein, S. A. Biller, S. M. Su, S. de Botton, Katharine E. Yen. IDH mutations and tumorigenicity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL02-04.
Abstract PL03-01: Working together to identify new epigenetic targets for cancer.
Authors: Bountra Chas
Published: August 2014

During my presentation, I will discuss: 1) how we are pooling the expertise and infrastructure of several big pharmas, with the disease and clinical expertise, and patients resources in academia, to accelerate novel target identification; 2) novel epigenetic targets which are worth further exploration; 3) how these efforts are facilitating science and proprietary programmes, including the creation of new biotechs; 4) our plans to establish human disease platforms for novel epigenetic target prioritization.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL03-01.

Citation Format: Chas Bountra. Working together to identify new epigenetic targets for cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL03-01.
Abstract PL04-01: Developing therapies for Ras driven cancers.
Authors: Cichowski Karen
Published: August 2014

The Ras pathway is one of the most commonly deregulated pathways in cancer. However Ras-driven tumors are often refractory to conventional therapies and a clinically effective targeted therapy has not yet been developed. Moreover, in some cancers KRAS mutations are used to exclude patients from being treated with specific targeted agents. As such, developing an effective targeted therapy for Ras-driven tumors is an important endeavor. We have been focusing on developing therapies for distinct Ras-driven cancers: Nf1-mutant cancers (nervous system malignancies and melanoma) as well KRas/p53-mutant non-small cell lung cancer (NSCLC). We have been using PI3K/mTOR inhibitors as a platform to develop novel combination therapies and have identified several new combinations, a subset of which are being evaluated in the clinic. We have also been deconstructing the mechanism by which these agents cooperate, which is providing insight into developing useful biomarkers and additional drug combinations.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL04-01.

Citation Format: Karen Cichowski. Developing therapies for Ras driven cancers. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL04-01.
Abstract PL04-03: Selective inhibition of K-Ras G12C through allosteric control of GTP affinity and effector interactions.
Authors: Ostrem Jonathan M. , Peters Ulf , Sos Martin L. , Wells James A. , Shokat Kevan M.
Published: August 2014

Somatic mutations in the small GTPase K-Ras are the most common activating lesions found in human cancer, and are generally associated with poor response to standard therapies1-3. Efforts to directly target this oncogene have faced difficulties due to its picomolar affinity for GTP/GDP4 and the absence of known allosteric regulatory sites.Oncogenic mutations result in functional activation of Ras family proteins by impairing GTP hydrolysis5,6. With diminished regulation by GTPase activity, the nucleotide state of Ras becomes more dependent upon relative nucleotide affinity and concentration. This gives GTP an advantage over GDP7 and increases the proportion of active GTP-bound Ras. Here, we report the development of small molecules that irreversibly bind to a common oncogenic mutant, K-Ras G12C.These compounds rely on the mutant cysteine for binding and therefore do not affect the wild type protein (WT). Crystallographic studies reveal the formation of a new pocket that is not apparent in previous structures of Ras, beneath the effector binding switch-II region. Binding of these inhibitors to K-Ras G12C disrupts both switch-I and switch-II, subverting the native nucleotide preference to favor GDP over GTP and impairing binding to Raf. Our data provide structure-based validation of a novel allosteric regulatory site on Ras that is targetable in a mutant specific manner.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL04-03.

Citation Format: Jonathan M. Ostrem, Ulf Peters, Martin L. Sos, James A. Wells, Kevan M. Shokat. Selective inhibition of K-Ras G12C through allosteric control of GTP affinity and effector interactions. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL04-03.
Abstract PR03: Selective sensitization of mutant K-Ras cancer cells to DNA damage based therapies by targeting wild type H- and N-Ras.
Authors: Grabocka Elda , Pylayeva-Gupta Yuliya , Yemanaberhan Eyoel , Lubkov Veronica , Taylor Laura , Bar-Sagi Dafna
Published: August 2014

Mutations in Kras are highly prevalent in human cancers and are strongly predictive of resistance to chemotherapy. As the constitutive activation of K-Ras has been believed to confer functional autonomy and dominance over the wild type Ras forms, it has been thought that wild type Ras forms are dispensable to the mutant K-Ras driven tumorigenic phenotype. Here we demonstrate a functional dependence of mutant K-Ras driven tumors on wild type Ras for the activation of the DNA damage response, and that this dependence can be exploited to specifically sensitize K-Ras cancers to DNA[[Unable to Display Character: –]]damage-inducing agents. We show that in mutant K-Ras cancer cells, wild type H-Ras and N-Ras are required for the activation of Chk1, the G2 DNA damage checkpoint, and the cellular response to DNA-damage-inducing chemotherapy. Specifically, we show that targeted depletion of wild type H- and N-Ras in mutant K-Ras cancer cells leads to the hyperactivation of the Erk/p90RSK and PI3K/Akt pathways, and as a consequence, the phosphorylation of Chk1 at an inhibitory site, Ser 280. The resulting inhibition of ATR/Chk1 signaling abrogates the activation of the G2 DNA damage checkpoint, and confers a specific sensitization of mutant K-Ras cancer cells to DNA damage therapeutic agents both in vitro and in vivo. Our results demonstrate a previously unappreciated role for wild type Ras in the DNA damage response of mutant K-Ras cancer cells and reveal a promising approach for targeting K-Ras-driven tumors.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PR03.

Citation Format: Elda Grabocka, Yuliya Pylayeva-Gupta, Eyoel Yemanaberhan, Veronica Lubkov, Laura Taylor, Dafna Bar-Sagi. Selective sensitization of mutant K-Ras cancer cells to DNA damage based therapies by targeting wild type H- and N-Ras. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PR03.
Abstract LB-204: Highly potent and optimized small-molecule inhibitors of MDM2 achieve complete tumor regression in animal models of solid tumors and leukemia.
Authors: Wang Shaomeng , Sun Wei , Yu Shanghai , Zhao Yu-jun , Kumar Sanjeev , McEachern Donna , Liu Liu , Bernard Denzil , Sun Duxin , Zou Peng , Li Xiaqin , Yi Han , Stuckey Jeanne , Long Jianting , Malek Sami , Yang Dajun , Kang Snmao , Guo Ming , Wood Brian , Leopold Lance , Sorensen Mel , Barriere Cedric , Meaux Isabelle , Dos-Santos Odette , Carry Jean-christophe , Abecassis Pierre-yves , Charlier Anne , Ferey Vincent , Garciaecheverria Carlos , Lengauer Christophe , Debussche Laurent
Published: August 2014

Activation of p53 by blocking the interaction of MDM2-p53 using non-peptide small-molecule inhibitors is being pursued as a promising new cancer therapeutic strategy. Although genetic activation of p53 has been shown to achieve complete tumor eradication in mice, the best small-molecule inhibitors of the MDM2-p53 interaction reported to date (Nutlins including RG7112 or first generation spiro-oxindoles such as AT219) can only inhibit tumor growth but fail to achieve significant tumor regression in animal models of human cancer. In the present study, we demonstrate, for the first time, that 2 highly optimized spiro-oxindole compounds, Compound A and Compound B, are capable of achieving complete tumor regression or even permanent cure in multiple xenograft models of human cancer (sarcoma, leukemia, prostate) without causing any significant signs of toxicity to animals. They bind to human MDM2 protein with Ki values of <1 nM, 5000-times more potent than the wild-type p53 peptide. These potent MDM2 inhibitors are capable of activating p53 at concentrations as low as 30–100 nM and induce robust p53-dependent cell cycle arrest and apoptosis against tumor cells with wild-type p53. Both compounds display good pharmacokinetic and pharmacodynamic profiles in animals. For instance, clearance is low in mice and moderate in dog representing 4 and 15 % of hepatic blood flow respectively. Importantly, excellent oral bioavailability was shown with 25–60 % F in dogs and 75 % F in mice and both compounds trigger rapid and sustained activation of pharmacodynamic biomarkers such as p53, p21, MDM2 and PUMA. Molecular profiling using large number of primary AML leukemia samples have identified that AML cells with wild-type p53 and FLT3-ITD mutation are exquisitely sensitive to apoptosis induction by our MDM2 inhibitors, suggesting an interesting clinical trial rationale. Toxicology studies are ongoing.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-204. doi:10.1158/1538-7445.AM2011-LB-204
Abstract 1027: EGFR targeting antibody SYM004 causes radiosensitization in tumor cells expressing wild-type K-Ras via modulation of MAPK signaling.
Authors: Saker Jarob , Huang Shyhmin , Park Lindsey , Pedersen Mikkel , Kragh Michael , Harari Paul
Published: August 2014

SYM004 is a promising new cancer therapeutic agent containing a mixture of two antibodies that target distinct epitopes on domain III of the EGFR. Treatment of tumor cells with SYM004 leads to clustering of EGFR followed by rapid internalization and degradation. We have recently shown that the combination of SYM004 and radiation therapy (RT) induces potent anti-tumor effects in head and neck (H&N) and lung cancer cell lines.

In this study we demonstrate that radiosensitization via SYM004 correlates with inhibition of DNA double strand break repair and induction of apoptosis. These effects are promoted by down regulation of the MAPK pathway. Treatment of SCC6 and H226 cell lines with SYM004 for 30min or 24h prior to irradiation leads to a 1.2 - 1.7 fold increase in unrepaired DNA double strand breaks (DSB) 24h after 2 Gy RT (detected via DNA repair foci formation). The fraction of early (1.8 -1.9 fold) and late (1.3 - 1.7 fold) apoptotic cells increased in both cell lines. However, these effects were reversible by treating the cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of Raf, for 30 min before RT at concentrations as low as 0.1 μM. In addition, mutant K-Ras cells lines A549 and H358 showed no radiosensitization after treatment with SYM004 for 24h prior to RT via DNA repair or apoptosis. Furthermore, transfection of SCC6 cell lines with a K-Ras version carrying an activating SNP (G12V) reversed the inhibitory effect on DNA repair induced by SYM004 in wild type K-Ras cells. These data suggest that the superior impact of combination therapy with SYM004 and RT on wild type K-Ras tumor cell lines reflects alterations in DNA repair and apoptosis via modulation of the MAPK pathway.

Citation Format: Jarob Saker, Shyhmin Huang, Lindsey Park, Mikkel Pedersen, Michael Kragh, Paul Harari. EGFR targeting antibody SYM004 causes radiosensitization in tumor cells expressing wild-type K-Ras via modulation of MAPK signaling. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1027. doi:10.1158/1538-7445.AM2013-1027
Abstract 1281: POLD3 is required for DNA damage response to endogenous and exogenous DNA damage in human cells.
Authors: Tian Xu , Swenberg James , Nakamura Jun
Published: August 2014

Methyl methanesulfonate (MMS) induces mutations in a nonlinear (hockey-stick-shaped) dose-response curve in DT40 cells, about 55% of which are located at A:T sites with a high frequency of A to T mutations. We hypothesized that these transversion mutations are due to base excision repair (BER) intermediates, such as abasic sites and single strand breaks derived from N3-methyladenine. One candidate polymerase to bypass abasic sites is polymerase delta (POLD). POLD is responsible for the lagging strand during DNA replication. POLD is referred to as a high fidelity DNA polymerase because of its ability to discriminate deoxynucleotides and its 3’->5’ exo-nuclease activity. One of the POLD subunits, POLD3, is important to recruit PCNA binding to the POLD core enzyme and is implied to have critical roles for translesion DNA synthesis. In yeast, cells deficient in POLD3 homologous gene POL32 are sensitive to DNA damaging agents and resistant to mutations caused by mutagens, such as MMS and UV. Here we generated POLD3 knock-down (KD) cells via lentivirus based shRNA in three different human cell lines. All POLD3 KD cells grow slower than the control cells, suggesting POLD3 function tolerates endogenous DNA lesions. Furthermore, we found that POLD3 KD cells were sensitive to various genotoxic agents including MMS and potassium chromate. To further investigate the role of POLD3 in the DNA damage response, we introduced a series of deletion mutations of POLD3 in POLD3 deficient cells. We found that both the POLD2 binding domain and the middle linker domain are critical for the activity of POLD3 while the C-terminal PCNA binding domain is dispensable. While there is little homology between human POLD3 and yeast POL32, function of these two proteins appears to be quite similar in structure biology analysis. Our results also suggest that POLD3 plays important roles to bypass DNA lesions caused by endogenous and various exogenous genotoxic agents.

Citation Format: Xu Tian, James Swenberg, Jun Nakamura. POLD3 is required for DNA damage response to endogenous and exogenous DNA damage in human cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1281. doi:10.1158/1538-7445.AM2013-1281
Abstract 1320: Effects of selective androgen-receptor and estrogen-receptor modulators on telomerase activity in melanoma and prostate cancer cells.
Authors: Lu Yan , Narayanan Ramesh , Wang Jin , Li Wei , Yepuru Murali , Liu Lingling , Loveless Vivian S. , Miller Duane D.
Published: August 2014

Male hormones and the androgen receptor (AR) are well-known key targets for prostate cancer therapy. The potential cause of a gender-based disparity in melanoma has been suspected for many years. A recent analysis suggests that female patients have a 30% survival advantage in cutaneous melanoma. Telomerase has been shown to add protective telomere repeats to chromosome endings and cause cancer cells to become immortal. We have recently discovered that the AR is expressed in melanoma cell lines. In current report, we tested the telomerase activity in lysates of both melanoma and prostate cancer cell lines. Telomeric repeat amplification protocol (TRAP) was carried out to test the activity of telomerase in melanoma A375, androgen-sensitive prostatic cancer LNCap and androgen-insensitive prostatic cancer PC-3 cell lines under treatments of steroid hormones, SARM and SERM compounds. The effects of sex hormones, selective androgen-receptor modulators (SARMs), and estrogen-receptor modulators (SERMs) on telomerase activity in both melanoma and prostate cells were investigated.

Citation Format: Yan Lu, Ramesh Narayanan, Jin Wang, Wei Li, Murali Yepuru, Lingling Liu, Vivian S. Loveless, Duane D. Miller. Effects of selective androgen-receptor and estrogen-receptor modulators on telomerase activity in melanoma and prostate cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1320. doi:10.1158/1538-7445.AM2013-1320
Abstract 1826: A critical role of LincRNA-Up6 in Bcr-Abl-induced tumorigenesis.
Authors: Chen Jilong , Guo Guijie , Kang Qingzheng
Published: August 2014

Long noncoding RNAs (lncRNAs) have been implicated in numerous human malignancies, including leukemia. Philadelphia-positive (Ph+) chronic myeloid leukemia (CML) is a stem cell disease induced by Bcr-Abl hybrid gene. In an attempt to provide better understanding of the mechanisms by which Bcr-Abl mediates cellular transformation, lncRNA microarray was used to determine the differentially expressed non protein-coding genes in K562 human leukemic cells in response to disruption of Bcr-Abl expression. All the lncRNA genes whose expressions were altered by at least 2-fold were clustered and displayed. We further investigated the functional involvement of selected lncRNA genes in regulating cell proliferation, cell survival and tumor formation. Interestingly, expression of a long intergenic noncoding RNA which we named as lincRNA-Up6 was found to be greatly up-regulated by silencing the Bcr-Abl expression in K562 cells. We showed that forced over-expression of lincRNA-Up6 sensitized imatinib-induced apoptosis in Bcr-Abl transformed cells. In addition, we observed that over-expression of lincRNA-Up6 significantly inhibited K562 xenograft growth in nude mice. Furthermore, we found that lincRNA-Up6 was involved in negative regulation of STAT5-dependent expression of anti-apoptotic Bcl-XL protein. Importantly, our experiments showed that expression of lincRNA-Up6 had profound effects on signaling pathways associated with development of leukemia stem cells of CML, resulting in inhibition of Bcr-Abl-mediated tumor formation. Together, these results suggest that lincRNA-Up6 suppresses Bcr-Abl-induced tumorigenesis, and the tumor suppressor function of lincRNA-Up6 may be of significance for the development of novel therapeutic strategies for treating CML.

Citation Format: Jilong Chen, Guijie Guo, Qingzheng Kang. A critical role of LincRNA-Up6 in Bcr-Abl-induced tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1826. doi:10.1158/1538-7445.AM2013-1826

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 1855: Regulation of proliferation of colon cancer cells by compounds affecting glycolysis including 3-bromopyruvate, 2-deoxyglucose and biguanides.
Authors: Lea Michael A. , Qureshi Mehreen , Buxhoeveden Michael , Gengel Nicolette , Kleinschmit Jessica , desBordes Charles
Published: August 2014

In earlier work we found that incubation of colon cancer cells with 2-deoxyglucose had an additive inhibitory effect on proliferation with the biguanides, metformin and phenformin, and blocked the acidification of the medium caused by incubation of cells with biguanides. In the present work, studies were performed with Caco-2, HCT116, HT29 and SW1116 colon cancer cells. Metabolism of glucose and acidification of the medium was greater with the more rapidly proliferating cells being greatest with HCT116 cells and least with SW1116 cells. We have seen that, as with 2-deoxyglucose, 3-bromopyruvate can also prevent the lowering of medium pH caused by biguanide treatment. . Inhibition of glucose metabolism paralleled the decrease in acidification of the medium. 3-bromopyruvate inhibited colon cancer cell proliferation. Additive effects with metformin and 3-bromopyruvate were not observed in any of the four colon cancer cell lines but some additive effects were seen with phenformin and 3-bromopyruvate. An additive effect was more notable in combined treatment with 3-bromopyruvate and 2-deoxyglucose. Induction of alkaline phosphatase activity serves as a marker of differentiation in colon cancer cells. The induction of alkaline phosphatase activity by butyrate was not consistently affected by combination with other agents that modified glucose metabolism. The drug combinations that were examined inhibited proliferation in wild type and P53 null HCT116 cells and affected colon cancer lines with different growth rates. Although metformin and phenformin increase glucose metabolism by colon cancer cells while 3-bromopyruvate and 2-deoxyglucose inhibit glucose metabolism, all these compounds have potential inhibitory action on the proliferation of colon cancer cells.

Citation Format: Michael A. Lea, Mehreen Qureshi, Michael Buxhoeveden, Nicolette Gengel, Jessica Kleinschmit, Charles desBordes. Regulation of proliferation of colon cancer cells by compounds affecting glycolysis including 3-bromopyruvate, 2-deoxyglucose and biguanides. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1855. doi:10.1158/1538-7445.AM2013-1855
Abstract 2145: PSMA-specific anti-tumor activity of the targeted-tubulysin conjugate, EC1169.
Authors: Reddy Joseph A. , Bloomfield Alicia , Dorton Ryan , Nelson Melissa , Vetzel Marilynn , Hahn Spencer , Vlahov Iontcho , Leamon Christopher
Published: August 2014

Prostate-specific membrane antigen (PSMA) is a biomarker that is overexpressed on prostate cancer, and it's also present on the neovasculature within many non-prostate solid tumors. We previously reported on EC0652, a 99mTc-labeled small molecule that specifically binds to PSMA-positive tumors and is currently being clinically evaluated for diagnostic imaging applications. Herein, we report on the construction and biological testing of novel tubulysin B-containing, companion therapeutic agents for the treatment of PSMA-expressing cancer. One of these compounds, EC1169, recently emerged as a lead candidate for preclinical development. This water-soluble conjugate was shown to have high affinity for PSMA-positive cells. When tested in vitro, EC1169 was found to inhibit the growth of PSMA-positive cells, but it displayed no activity against PSMA-negative cells. Brief treatment of nude mice bearing PSMA-positive LNCaP human xenografts with EC1169 led to complete remissions in 5/7 mice, and cures (i.e. tumor free >90 days post implantation) in 2/7 mice. Furthermore, this activity occurred in the absence of weight loss or major organ tissue degeneration. In contrast, the non-targeted tubulysin B drug proved to be inactive against the LNCaP tumor model when administered at doses near to or greater than the maximum tolerated level. PSMA-negative KB tumors did not appreciably respond to EC1169 therapy, thereby confirming this compound's targeted specificity for PSMA-expressing cells. Finally, treatment of LNCaP-bearing mice with docetaxel (the most active chemotherapeutic agent approved for prostate cancer), was found to produce only modest anti-tumor activity (2/4 partial responses, 1/4 cures), and this outcome was also associated with severe weight loss (18%). Taken together, these results strongly indicate that PSMA-positive tumors may be more effectively treated using highly potent, PSMA-targeted small-molecule drug conjugates using regimens that do not cause unwanted toxicity.

Citation Format: Joseph A. Reddy, Alicia Bloomfield, Ryan Dorton, Melissa Nelson, Marilynn Vetzel, Spencer Hahn, Iontcho Vlahov, Christopher Leamon. PSMA-specific anti-tumor activity of the targeted-tubulysin conjugate, EC1169. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2145. doi:10.1158/1538-7445.AM2013-2145
Abstract 2230: Interaction of SJG-136 with cognate sequences of oncogenic transcription factors.
Authors: Mantaj Julia , Thurston David E. , Rahman Khondaker M.
Published: August 2014

The pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are sequence-selective DNA minor-groove interacting agents. They have a chiral centre at their C11a(S)-position which provides them with the appropriate 3-dimensional shape to fit securely within the DNA minor-groove. They also possess a “soft” electrophilic imine moiety at their N10-C11 position which can form an aminal linkage with the C2-NH2 group of a guanine base. The PBD dimer SJG-136 is presently in Phase II clinical trials in ovarian cancer and leukaemia. Transcription factors act through direct or indirect binding to specific DNA consensus sequences within gene regulatory regions, or by forming a complex with other proteins which then act as transcription factors. Covalent or non-covalent interaction of small molecules with key consensus DNA bases can prevent a transcription factor from recognizing its cognate sequence, thus preventing expression of genes critical for the survival and proliferation of cancer cells. The cognate sequences of a number of oncogenic transcription factors are unusually rich in GC sequences and provide ideal alkylation substrates (for both inter- and intrastrand cross-links and mono-alkylation) for both PBD dimers (e.g. SJG-136) and PBD monomers, and there is growing evidence that PBDs exert their pharmacological effects through this mechanism. We have developed a reversed-phase ion pair HPLC/MS method as a tool to evaluate the interaction of DNA-binding molecules with oligonucleotides of varying length and sequences. Using this methodology along with custom-designed oligonucleotides containing the cognate sequences of the transcription factors NFκB, AP-1, EGR-1 and Stat3, all of which contain ideal GC-rich binding sequences for SJG-136, we have observed both kinetic and thermodynamic adduct formation with SJG-136. Crucially, we observed a significant difference in rate and extent of adduct formation between the different cognate sequences which could partly explain the differences in activity of SJG-136 toward different tumour cell lines. For example, SJG-136 formed an adduct rapidly with the NFκB sequence (>50% adduct within 3 hours), moderately with the STAT3 (>35% adduct within 3 hours) and EGR-1 cognate sequences (>30% adduct within 3 hours) while showing insignificant adduct formation with the AP-1 cognate sequence (< 5% adduct within 3 hours) even though their GC contents are comparable. These findings add to knowledge of the possible mechanism of SJG-136, and could help with interpretation of the activity of SJG-136 in various biochemical and pharmacological assays.

Citation Format: Julia Mantaj, David E. Thurston, Khondaker M. Rahman. Interaction of SJG-136 with cognate sequences of oncogenic transcription factors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2230. doi:10.1158/1538-7445.AM2013-2230