bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2756: Combination therapy of doxorubicin and the acid-sensitive albumin-binding prodrug of doxorubicin INNO-206 induces complete regressions in a xenograft pancreatic carcinoma model demonstrating excellent tolerability
Authors: Kratz Felix , Azab Samar S E E A , Zeisig Rainer , Fichtner Iduna , Warnecke Andre
Published: August 2012

Combination therapy of macromolecular prodrugs with clinically established low-molecular weight anticancer drugs is a field of research that has been insufficiently explored to date. Recently, we investigated the anticancer effect of a combination of doxorubicin with the clinically assessed albumin-binding prodrug INNO-206, the (6-maleimidocaproyl)hydrazone of doxorubicin, in an ovarian carcinoma xenograft model (A2780). The combination achieved complete remissions as did therapy with INNO-206 alone, but was far better tolerated. Due to these encouraging results, we extended our combination trials to a more chemoresistant tumor indication, i.e. pancreatic cancer. Thus, we compared the following weekly schedules against the MiaPaca-2 xenograft model (i.v. administration): 3 x 6 mg doxorubicin (MTD), 3 x 24 mg/kg INNO-206 (doxorubicin equivalents, MTD), 3 x 3 mg/kg doxorubicin followed 6 h later by 3 x 12 mg/kg INNO-206, and 3 x 12 mg/kg INNO-206 followed 6 h later by 3 x 3 mg/kg doxorubicin. Whereas therapy with doxorubicin only produced a moderate tumor inhibition, all other therapy arms induced complete long-term remissions until the end of the experiment on day 44. However, there were significant differences in the tolerability as assessed by the body weight changes: whereas therapy at the MTD of INNO-206 (3 x 24 mg/kg) produced a body weight loss of −16 %, therapy with 3 x 12 mg/kg INNO-206 followed 6 h later by 3 x 3 mg/kg doxorubicin produced −7 % body weight loss, but 3 x 3 mg/kg doxorubicin followed 6 h later by 3 x 12 mg/kg INNO-206 produced a body weight gain of + 2 % as a clear indication of minimal systemic toxicity. This animal study is to best of our knowledge the first investigation demonstrating that a combination of an albumin-binding prodrug with its free parent drug not only has clear therapeutic advantages over the free drug but that the time-dependent schedule has a critical influence on the overall tolerability and results in its best case in a 100 % cure rate without causing any body weight loss. The current working hypothesis to explain this surprising effect is that the combination of doxorubicin with an albumin-binding prodrug of doxorubicin with acid-sensitive properties enables a more homogenous distribution of the drugs in the tumor due to different uptake mechanisms in a heterogeneous solid tumor (EPR effect for INNO-206 and free diffusion into the tumor interstitium for doxorubicin).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2756. doi:1538-7445.AM2012-2756
Abstract 2759: Targeting NF2 deficient meningiomas with combinations of small molecule inhibitors and radiation
Authors: Baia Gilson S. , Woodworth Graeme , Ford Eric , Riggins Gregory
Published: August 2012

Meningiomas are common tumors of the central nervous system and are the second most prevalent tumors in Neurofibromatosis type 2 patients. Despite their high frequency, currently there are no chemotherapeutic options for these tumors and treatment is limited to surgery and various forms of radiation therapy either as adjuvant or primary therapy. Some tumors are unresectable due to location and have histhopathologic aggressive features (designated as WHO grade II and III) with higher recurrence rates. When treatment is recommended, these tumors almost uniformly receive some form of radiation therapy. The aim of this study was to find new therapeutic options to couple with radiation, given its common use with non-surgical meningiomas. We are interested in targeting oncogenic pathways in the context of loss of the NF2 gene, which represents the most common genetic alteration in meningiomas, present is 50-70% of sporadic tumors and all of NF2 cases. We used cell-based assays searching for small molecule inhibitors that showed prevalent efficacy against NF2-deficient cells. Cell proliferation and clonogenic assays were employed to investigate the potential synergy effect of drugs and radiation combinations. Three pairs of NF2 isogenic meningioma cells (AC1, SF6717 and KT21MG1) were used to screen libraries of FDA approved compounds. The primary screen was performed using KT21MG1 cells. The top 5% compounds (86 compounds) showing preferential inhibition of NF2-deficient cells were selected for further validation. The secondary screen was used to validate useful targets with AC1 and SF6717 cells. Twelve compounds (∼15%) showed prevalent inhibitory activity on these cells. Small molecules targeting mammalian target of rapamycin (mTOR) and vascular endothelial growth factor receptor (VEGFR) showed preferential synergistic inhibition of NF2 cells with radiation, compared to either radiation or drug treatment alone. Currently, preclinical testing is in progress to investigate the efficacy of these inhibitors in combination with radiation in a meningioma mouse model.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2759. doi:1538-7445.AM2012-2759
Abstract 2761: Co-administration of the short-chain sphingolipid N-octanoyl-glucosylceramide improves doxorubicin therapy by enhancing intracellular drug accumulation in vivo
Authors: van Hell Albert J. , Koning Gerben , Jonkers Jos , Verheij Marcel
Published: August 2012

BACKGROUND: Plasma membranes are a effective barrier that prevent exogenous therapeutics, including cytostatic drugs, to reach their intracellular targets and become active. Membrane traversal of most drugs is therefore sub-optimal and remains a major limitation for clinical efficacy. We identified a well-defined class of short-chain lipids that modulate the plasma membrane and facilitate the cellular accumulation of amphiphilic drugs, including doxorubicin. RESULTS: A liposomal co-formulation of the short-chain lipid N-octanoylglucosylceramide (GC) and doxorubicin was applied in a genetically engineered mouse (GEM) breast tumor model (Wcre;Cdh1F/F;Trp53F/F). These tumors, which are resistant to a variety of conventional and biological cytostatic therapies, responded to doxorubicin treatment when combined with the membrane modulation strategy. Co-administration of GC generated a sustained anti-tumor response and significantly improved overall survival (30 days versus 11 days for control; p < 0.005). Using a nuclear isolation procedure, we showed that the presence of GC enhanced the intracellular tumor accumulation in vivo by a factor 1.9 (p < 0.05). In contrast, the accumulation within normal heart tissue was not elevated. The latter data are in agreement with in vitro experiments using cultured cardiac myocytes. When compared to either clinically available formulations of doxorubicin (free or PEGylated liposomal doxorubicin) a favorable efficacy, pharmacokinetic and toxicity profile was obtained by co-formulation of GC with doxorubicin. CONCLUSION: The short-chain sphingolipid GC improves the therapeutic ratio in multi-drug resistant GEM breast tumors by enhancing the intracellular tumor accumulation of doxorubicin while limiting normal tissue exposure.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2761. doi:1538-7445.AM2012-2761
Abstract 2766: Targeting heat shock proteins: Novel strategies for treating prostate cancer
Authors: Adelaiye Remi M. , Ellis Leigh , Pili Roberto
Published: August 2012

Prostate cancer (PCa) is the second most common form of cancer in men. Treatment for prostate cancer remains a challenge, particularly for castrate resistant prostate cancer. Hormonal therapy such as androgen ablation often fails as cancer cells utilize alternative mechanisms for survival and eventually progress to castrate resistant PCa. Currently, understanding of molecular mechanisms underlying castrate resistant PCa development is limited. Strong evidence demonstrates that castrate resistant PCa continues to depend on androgen receptor signaling. Novel compounds targeting androgen receptor activity and androgen synthesis are currently under investigation in preclinical and clinical studies; however alternate therapeutic approaches for castrate resistant PCa are needed. Heat-shock protein 90 (Hsp90) is an abundant molecular chaperone and plays a crucial role in structural formation and folding of a variety of proteins including androgen receptor, Akt, and other oncogenic proteins. Inhibition of Hsp90 creates the potential to suppress tumor activity as enforced disassociation induces proteosomal degradation of Hsp90 client proteins. This study utilized four genetically defined murine PCa epithelial cell lines, MYC-CaP (AR+ amplified, Pten +), MYC-Cap css (Castrate resistant, AR= amplified, Pten+), Pten-CaP E2 (Androgen sensitive, AR+, Pten null), and Pten-CaP cE2 (Castrate resistant, AR+, Pten null) to investigate the cellular response to Hsp90 inhibition. Cells were exposed in vitro to NVP-AUY922, a novel Hsp90 inhibitor at increasing concentrations for 24 and 48 hours. Results demonstrated that AUY922 treatment induced reduction in overall growth in all cell lines, with Pten-CaP and castrate resistant Pten-CaP being more sensitive (IC50 = 10nM) than MYC-CaP and MYC-Cap css (IC50 = 25nM) cells. Inhibition of cell growth was also indicated by induced cell cycle arrest in all cell lines, though AUY922 treatment did not result in significant increase in cell membrane permeability. Overall, our preliminary data indicates that AUY922 exhibits strong anti-growth effects in PCa cell lines and warrants further investigation as a potential novel targeted therapy to treat advanced and castrate resistant PCa.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2766. doi:1538-7445.AM2012-2766
Abstract 2768: IDH1057, A novel, synthetic, small molecule inhibitor of heat shock protein 90(Hsp90)
Authors: Kwon Jin-Sun , Moon An-Na , Park Joon-Tae , Hong Soo-Jung , Jeong Jin-Ah , Kwon Sung-Wook , Lee Myong-Jae , Jang Hyeon-Soo , Yeon Seung-Woo , Lee Hong-Sub , Kang Jae-Hoon
Published: August 2012

Backgroud: The molecular chaperone Heat shock protein 90(Hsp90) governs the stabilization and activity of an array of over 100 ‘client proteins’, many of which are key signaling molecules involved in cell proliferation, survival, and transformation. A significant number of these client proteins are oncogenic in nature, including the protein kinases Her2, C-Raf, B-Raf, and AKT. We report here that IDH1057 is structurally distinct from a geldanamycin derivative, tanespimycin(17-AAG) as a novel and potent small molecule Hsp90 inhibitor that binds to the NH2-terminal ATP-binding pocket of Hsp90. Results: IDH1057 exhibited superior binding affinity for the ATPase domain of Hsp90(IDH1057, human Hsp90α FP IC50<150 nM) compared to 17-AAG(IC50 =456.3 nM) in vitro. IDH1057 also markedly inhibited proliferation in a broad panel of human tumor cell lines(IC50α100 nM) and depleted Her2 in SKBR3 breast cancer cells(IC50<50 nM). 10 NSCLC cell lines were relatively sensitive to IDH1057, irrespective of EGFR, Her2 or KRAS mutational status. IDH1057 was also highly effective against cell lines that displayed resistance to erlotinib. IDH1057 efficiently inhibited cell proliferation in 8 breast cancer cell lines including triple-negative breast cancer(TNBC) cell lines such as BT-20, Hs578T and MDA-MB-231. Exposure to IDH1057 led to a rapid and dramatic degradation of key signaling molecules in BT474 cells. Based on these results, we examined in vivo anti-tumor activity of IDH1057 in BT474 breast cancer xenografts. Following once daily oral dosing of IDH1057 at 200mg/kg on a weekly 5-day-on and 2-day-off schedule for 4 weeks, this compound showed statistically significant tumor growth inhibition(TGI=84.5%) and was well-tolerated with no observable body weight loss. A2780 ovarian cancer xenografts in mice treated orally with IDH1057 also resulted in potent tumor growth inhibition. More importantly, IDH1057 displayed favorable oral PK profiles in mice. Additionally, we performed in vitro ADME assays to characterize a new series of small molecule inhibitors. IDH1057 exhibited high metabolic stability in liver microsomes from human, mouse and beagle(≥60%). Five human CYP isoforms were not significantly inhibited by IDH1057 at 10uM. IDH1057 had moderate permeability in MDCK permeability assay(Papp=4.7x10−6 cm/sec). Conclusion: Our results indicate that IDH1057 is a novel and fully synthetic Hsp90 inhibitor with strong anti-tumor activity in vitro and in vivo. IDH1057 is a promising and orally active drug candidate for cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2768. doi:1538-7445.AM2012-2768
Abstract 2777: Suppression of multiple myeloma via non-canonical inhibition of NF-κB
Authors: Hovde Stacy , Lansdell Theresa A. , Azevedo Lauren , Tepe Jetze J. , Henry Ronald W.
Published: August 2012

Multiple myeloma is a deadly disease for which treatment has significantly improved with the introduction of the proteasome inhibitor bortezomib. The mechanism of cell death invoked by proteasome inhibition is unknown, but likely involves multiple pathways, including downregulation of NF-κB activity, stabilization of pro-apoptotic factors, and induction of the unfolded protein response, which may be especially critical for apoptosis of B-cell tumors. However, most patients ultimately experience disease relapse, and novel treatments are clearly necessary. We have developed a novel class of proteasome inhibitors called trans-imidazolines that target the proteasome differently from bortezomib and exhibit substantial anti-inflammatory properties when tested in mouse models of rheumatoid arthritis. The purpose of the current studies was to determine the efficacy of these small molecule anti-inflammatory agents for inhibition of multiple myeloma proliferation and survival. For these studies, trans-imidazoline efficacy was initially determined in vitro against a panel of multiple myeloma cell lines with effects on apoptotic induction determined by fluorescent activated cell sorting analysis. Subsequent studies were expanded to examine multiple myeloma tumor growth in mouse xenograft assays. Component levels of the NF-κB pathway were examined by Western blot analyses and immunofluorescent staining after challenge with exogenous cytokines. The biochemical mechanism of trans-imidazoline function was further explored in vitro using proteasome assays of fluorescently tagged peptide substrates. Our data indicates that trans-imidazolines impede IαBβ turnover in response to TNFα treatment and are consequently effective inhibitors of NF-κB activity for transcriptional activation. As NF-κB mediates key pro-survival roles in multiple myeloma, these compounds were found to induce apoptosis in multiple myeloma cells as rapidly as bortezomib, and demonstrated impressive inhibition of RPMI-8226 tumor growth in mice. Importantly, trans-imidazolines are equally effective inhibitors of bortezomib-resistant tumor cell proliferation. Consistent with these observations, we found that trans-imidazolines inhibit proteasome activity via a non-competitive mechanism that is distinct from the active site competitive inhibition mechanism displayed by bortezomib. As acquired resistance to bortezomib often occurs via increased expression of its proteasome target, trans-imidazolines thus offer an alternative treatment option for recurrent disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2777. doi:1538-7445.AM2012-2777
Abstract 2783: Inhibition of prosurvival autophagy by the BH3-mimetic obatoclax sensitizes antiestrogen-resistant breast cancer cells to apoptosis
Authors: Schwartz Jessica , Shajahan Ayesha , Liu Minetta , Clarke Robert
Published: August 2012

Antiestrogens (AEs) have long been a standard treatment for estrogen receptor-positive (ER+) breast cancer patients. However, antiestrogen resistance, either de novo or acquired, is a major hurdle for effective therapy in breast cancer patients. To address this, the underlying mechanisms of antiestrogen resistance must be understood. One common mechanism by which AE resistant cells thrive is by overexpressing BCL2 and its antiapoptotic family members, which allows cancer cells to survive under conditions that would normally cause apoptosis. We discovered that the BH3-mimetic, obatoclax (GX15-070), significantly reduces cell proliferation and, in combination with fulvestrant or tamoxifen, results in a synergistic inhibition of cell growth in AE resistant breast cancer cells. Obatoclax exhibits potency against BCL2, BCL-XL, BCLW, MCL1, and A1 and is currently being used in clinical trials directed at lymhomas and leukemia. However, the molecular mechanisms of cell death by obatoclax are unclear. We show that obatoclax induces apoptosis and autophagosome formation in AE-resistant breast cancer cells. To compensate for the increase in autophagosomal formation as measured by LC3, obatoclax also induces lysosome formation to prepare for cellular breakdown. This study is the first to show that obatoclax inhibits prosurvival autophagy by preventing the degradation of LC3 and p62 through a cathepsin-dependent mechanism. Furthermore, overexpression of BCL2 in breast cancer cells “primes” the cells with BH3-only proteins and renders the cancer cell sensitive to treatment with obatoclax. Collectively, these data support exploration of clinical trials combining an AE and the BCL2 inhibitor, obatoclax, for the treatment of AE-resistant breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2783. doi:1538-7445.AM2012-2783
Abstract 290: A Twist1 code of p53 inactivation
Authors: Piccinin Sara , Tonin Elena , Sessa Sara , Pivetta Flavia , Rosano Camillo , Rossi Sabrina , Tos Angelo Paolo Dei , Doglioni Claudio , Maestro Roberta
Published: August 2012

Twist proteins have been shown to contribute to cancer development and progression by impinging on different regulatory pathways, but their mechanism of action is poorly defined. By investigating the role of Twist in sarcomas, we identified an unprecedented mechanism of destabilization of p53. We show that Twist1 and MDM2 overexpression are mutually exclusive in these tumors and provide evidence that, by physically hindering p53 key phosphorylation, Twist1 facilitate MDM2:p53 complex formation and p53 degradation. This study suggests the existence of a Twist code of p53 inactivation in sarcomas and provides the proof of principle that targeting the Twist:p53 interaction may offer additional avenues for cancer treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 290. doi:1538-7445.AM2012-290
Abstract 2906: Preclinical systems to study the biodistribution of nanoparticle delivery in pancreatic ductal adenocarcinoma
Authors: Collisson Eric A. , Zuckerman Jonathan , Wang Donghui , Phojanakong Paul , Gale Aaron B. , Choi Chung Hang J. , Hann Byron , McCormick Frank , Davis Mark
Published: August 2012

Pancreatic Ductal Adenocarcinoma (PDA) is a deadly disease, with no effective available treatment. Primary chemoresistance is common and has been attributed to the hypovascularity characteristic of the disease and the dense desmoplastic response that accompanies virtually every case of PDA. Effectively delivering therapeutic anticancer agents to PDA cells is therefore a specific, difficult and understudied problem in PDA that must be resolved for successful treatments to emerge. With the goal of eventually delivering drug payloads via nanoparticles (NP), we used well-defined mouse models of the disease to iteratively test NP distribution to both the cancerous and normal pancreas. Minimal deposition was observed in normal pancreas after intravenous or intraperitoneal administration of a variously sized (25nm or 40nm) NP. Surprisingly, abundant NP deposition was seen in both syngenic xenografted and autochthonous KPC models of PDA. NP deposition tended to be greater with IP administration and was enriched in stoma rich tumor regions. These findings have encouraging ramifications for delivery of depot or novel (e.g. siRNA, radiopharmaceutical, etc.) agents in this deadly disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2906. doi:1538-7445.AM2012-2906
Abstract 2908: Biological evaluation of paclitaxel-peptide conjugates as a model for MMP2-targeted drug delivery
Authors: Yamada Roppei , Xu Shili , Neamati Nouri
Published: August 2012

Paclitaxel (PTX) is a highly effective cytotoxic agent widely used for the treatment of several solid tumors. However, PTX shows dose-limiting cytotoxicity and in most cases induces drug resistance followed by failure in treatment. To enhance the therapeutic index of a given drug, various drug delivery methods have been explored to systemically deliver sufficient amount of the drug to the desired site. In the present study, we designed and synthesized two PTX prodrugs by conjugating PTX at different sites with an octapeptide (AcGpLGIaGQ) that can be cleaved by MMP2 at tumor sites. As a result, PTX is expected to be released at the tumor sites, absorbed by the tumor cells, and thereby inhibit the tumor growth. We evaluated the in vitro activities of the two drugs in a panel of drug-sensitive and -resistant cancer cell lines and their in vivo efficacies in a HT1080 fibrosarcoma mouse xenograft model that overexpresses MMP2. Our in vitro results showed that the PTX-AcGpLGIaGQ conjugates inhibited cancer cell proliferation with higher activity compared to that observed for free PTX, both of which were mediated by an arrest of G2/M-phase of the cell cycle. Consistent with the in vitro results, treatment with PTX-octapeptide conjugate resulted in extensive areas of necrosis and a lower percentage of proliferating cells in xenograft tumor sections. Together, our results indicate the potential of the tumor-targeted delivery of PTX to exploit the specific recognition of MMP2, reduce toxicity, and selectively kill tumor cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2908. doi:1538-7445.AM2012-2908
Abstract 2909: Doxorubicin-loaded zirconium phosphate nanoparticles for intracellular anticancer drug delivery to breast cancer cells
Authors: González Millie L. , Diaz Agustin , Cabán Jennifer , Colón Jorge , Báez Adriana
Published: August 2012

Purpose: Doxorubicin (DOX), is an anthracycline antibiotic widely used for the treatment of several solid tumors but its usage is limited by serious side effects to healthy tissues. The purpose of this study was to explore the effectiveness of zirconium phosphate nanoparticles (ZrP) as carrier of anticancer agents (ie. DOX) to tumor cells and potentially reduce side effects to healthy tissue. Methods: Confocal Microscopy (CM) was used to assess internalization and localization of doxorubicin-loaded ZrP nanoparticles (DOX:ZrP) in MCF-7 breast cancer cell line. The cytotoxicity of ZrP and DOX:ZrP in MCF-7 and MCF-10A cells was studied using MTT assay. Results: Co-internalization of DOX and ZrP nanoparticles into the cytoplasm and nucleus of MCF-7 cells was detected using CM. A high fluorescence in cell nucleus demonstrated DOX release from ZrP nanoparticles. ZrP alone is non-toxic to MCF-7 and MCF-10A cells. After a 48-hour treatment of MCF-7 cells with DOX:ZrP or DOX alone the IC50 obtained was 23µM and 24 µM, respectively. DOX cytotoxicity to MCF-7 cells after 72-hour treatment was three times higher than DOX:ZrP with IC50 of 0.74 µM and 3.15 µM, respectively. Conclusion: ZrP nanoparticles are internalized and can effectively deliver DOX to the interior of cancer cells. ZrP nanoparticles might provide a versatile platform for transportation of anticancer agents resulting in improved cancer therapy by reducing the side effects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2909. doi:1538-7445.AM2012-2909
Abstract 2913: Identification of GSK2636771, a potent and selective, orally bioavailable inhibitor of phosphatidylinositol 3-kinase-beta (PI3Kα) for the treatment of PTEN deficient tumors
Authors: Rivero Ralph A. , Hardwicke Mary Ann
Published: August 2012

Dysregulation of the PI3K pathway is one of the most common causes of tumorigenesis. Aberrant pathway activation occurs frequently through loss of the tumor suppressor protein, PTEN. Loss of PTEN protein has been observed in approximately 40% of glioblastoma, 50% of prostate, 57% of endometrial cancers, as well as in a number of other tumor types, including melanoma and breast cancers. Preclinical studies have shown that selective depletion of the PI3Kα isoform inhibits tumorigenesis and reduces downstream PI3K signaling in PTEN deficient tumors. This data presents an opportunity for a clear patient selection strategy based on the presence or absence of PTEN. During an extensive knowledge-based lead identification and optimization effort starting from the reported PI3K beta-selective compound TGX-221, we identified several unique series of potent and selective inhibitors with less than desirable pharmacokinetic properties. Through a combination of structure-based and knowledge-based design, we ultimately identified substituted benzimidazole GSK2636771 as a potent, orally bioavailable, PI3K beta-selective inhibitor. The evolution of our selective inhibitors, leading to the discovery, design, and optimization of GSK2636771 and related analogs, will be described.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2913. doi:1538-7445.AM2012-2913
Abstract 2915: Discovery and characterization of OSI-296, a dual inhibitor of cMET and RON kinases
Authors: Steinig Arno G. , Li An-Hu , Wang Jing , Kleinberg Andrew , Dong Hanqing , Wang Ti , Gavagan Kathryn M. Stolz , Jin Meizhong , Tavares-Greco Paula , Peng Yue , Kahler Jen , Castaldo Linda , McCormack Siobhan , Kan Julie , Albertella Mark , Cooke Andy , Turton Roy , Bittner Mark , Franklin Maryland , Landfair Darla , Gokhale Prafulla , Wild Robert , Pachter Jonathan , Epstein David , Mulvihill Mark J.
Published: August 2012

cMET and RON are receptor tyrosine kinases of the MET proto-oncogene family that are activated by their respective ligands HGF and MSP. Signaling through the cMET/HGF system can be deregulated in cancer by HGF-dependent autocrine activation, gene amplification, and/or the presence of activating mutations, among others, while for RON, constitutively active variants generated by alternative splicing or methylation-dependent promoter usage [short-form RON (sfRON)] have been identified. Approaches to abrogate aberrant cMET and RON signaling that have led to agents in clinical trials include inhibiting their kinase function with small molecules. We report here the discovery and characterization of OSI-296, a dual inhibitor of cMET and RON. The compound exhibited selectivity in a panel of 96 kinases with potent activity against cMET, including common Y1230 mutants, and RON. OSI-296 blocked cMET autophosphorylation in MKN45 cells, resulting in dose-dependent inhibition of downstream ERK, AKT, and STAT3 phosphorylation. It also showed potent cellular activity in ELISA-format sfRON and caRON cell mechanistic assays that we developed, resulting in dose-dependent inhibition of downstream ERK and AKT phosphorylation. OSI-296 showed a PK profile in rodents suitable for oral dosing with >70% bioavailability. In multiple xenografts models (cMET: MKN45, SNU-5, U87MG; RON: caRON), significant tumor growth inhibition was observed upon oral dosing with regression at higher doses. OSI-296 was very well tolerated with little body weight loss and no adverse effects even at the highest tested dose of 300 mg/kg p.o. qdx14. Solid PK/PD/TGI correlations have been established wherein >90% inhibition of cMET or RON phosphorylation sustained over 24 h by OSI-296 translated to 100% TGI. In summary, OSI-296 was shown to be a well tolerated, dual inhibitor of cMET and RON with in vivo activity in mouse xenografts models for both targets upon oral dosing.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2915. doi:1538-7445.AM2012-2915
Abstract 2917: Design, synthesis and biological evaluation of two chemical classes as novel small molecule Mcl-1 inhibitors
Authors: Bajwa Naval , Abulwerdi Fardokht , Liao Chenzhong , Mady Ahmed , Bernardo Julie Di , Azmi Asfar , Cierpicki Tomek , Stuckey Jeanne , Showalter Hollis , Mohammad Ramzi , Nikolovska-Coleska Zaneta
Published: August 2012

The anti-apoptotic myeloid cell leukemia protein Mcl-1, a member of the Bcl-2 family proteins, has a critical and distinct role(s) in maintaining cell survival and is emerging as an independent and promising therapeutic target. Using structure-based design, two classes of small molecule Mcl-1 inhibitors were developed with IC50 values ranging from 50 nM to 75 μM, based on the lead compounds identified from high throughput screening. The structure-activity relationships (SAR) of these compounds were analyzed and chemical features of both series that are important for potency and selectivity on Mcl-1 were identified. The HSQC-NMR spectroscopy studies combined with molecular docking and dynamics simulations demonstrated that both classes of compounds occupy the BH3 binding site in Mcl-1 protein mimicking two conserved hydrophobic residues from BH3 binding motif. The most potent analogues antagonize Mcl-1 on the functional level and they induce release of cytochrome c, inhibit cell growth and induce apoptosis in Bax/Bak-dependent manner in pancreatic and melanoma cancer cells with high levels of Mcl-1. The knowledge gained through these studies provides promise for future design and expansion of these series towards development of potent small-molecule Mcl-1 inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2917. doi:1538-7445.AM2012-2917
Abstract 292: Modulation of cyr61/ccn1 expression in human cell lines by the polyphenolic compound resveratrol
Authors: Monzon Ricardo , Prokop Jennifer
Published: August 2012

Resveratrol is the active compound in red grape skin believed to contribute to the protective effects of red wine in heart disease and has been implicated in the modulation of certain cancers. The matricellular protein CCN1/Cyr61 is involved in the regulation of cellular activities that control growth, programmed cell death, cellular motility and cell adhesion. Interestingly, many of the regulatory pathways that affect CCN1/Cyr61 expression are also affected by resveratrol action. In order to examine the possible link between CCN1/Cyr61 action and resveratrol's effects, human cell lines were used to analyze resveratrol's effects on CCN1/Cyr61 expression and function. Increased levels of CCN1/Cyr61 expression were observed in cells treated with resveratrol alone or combined with the stimulatory agents phorbol ester and epidermal growth factor (EGF). Analysis of CCN1/Cyr61 protein expression and cellular functions also revealed modulatory effects of reseveratrol treatment, however the role of upstream regulatory pathways in mediating reseveratrol action has yet to be addressed. Nevetheless, these studies offer preliminary evidence for the regulation of CNN1/Cyr61 expression by a putative modulator of cellular processes involved in heart disease and cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 292. doi:1538-7445.AM2012-292
Abstract 2921: Critical mediation of E2-induced apoptosis through c-Src in long-term estrogen deprived breast cancer cells
Authors: Fan Ping , Griffith Obi L. , Anur Pavana , Kim Helen R. , Gray Joe W. , Jordan V. Craig
Published: August 2012

Our previous publication showed that physiological concentrations of estrogen (E2) could trigger apoptosis of long-term E2 deprived breast cancer cells (MCF-7:5C) (Lewis et al. JNCI 2005; 97:1746-59). This new targeted strategy provides novel therapeutic approaches to endocrine resistant breast cancer. A phase II clinical trial reported that E2 provided a clinical benefit for aromatase inhibitor-resistant advanced breast cancer patients. However, only 30% of patients receive clinical benefit (Ellis MJ et al. JAMA 2009;302:774-80). This prompted us to investigate the mechanisms underlying E2-induced apoptosis to find strategies to increase the therapeutic responsiveness. c-Src is currently of interest, as it is an important adapter protein of ER in breast cancer cells. Here, we found that E2 stimulated c-Src phosphorylation in MCF-7:5C cells and 4-hydroxytamoxifen (4-OHT) could block this stimulation which demonstrated that E2 activated c-Src through ER. The specific inhibitor of c-Src, PP2, could block c-Src activation induced by E2. E2 rapidly activated growth pathways within minutes in MCF-7:5C cells and PP2 could block this non-genomic pathway. E2 was also able to activate Akt/MAPK pathways after 24 hour treatment which could be blocked by inhibition of c-Src. These data showed that c-Src mediated downstream signaling pathways of ER in MCF-7:5C cells. Characteristic E2-induced apoptosis occurred around 72 hour treatment with E2, unexpectedly, inhibition of c-Src could significantly block E2-induced apoptosis which implied that c-Src played a critical role in E2-induced apoptosis. Further examination through transcriptome analysis confirmed that E2 widely induced apoptosis-related pathways. Consistent with the biological experiments, PP2 could completely abolish the apoptosis pathways induced by E2. These data illustrate that c-Src acts as a critical molecule to mediate the downstream signaling of ER (including E2-induced apoptosis) in MCF-7:5C cells. It provides an important rationale for clinical trial with c-Src inhibitors in aromatase inhibitors resistant patients, especially avoiding in combination with physiological levels of E2. Acknowledgements This work (VCJ and JWG) is supported by the SU2C (AACR) Grant (SU2C-AACR-DT0409).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2921. doi:1538-7445.AM2012-2921
Abstract 2931: Inherited variation at chromosome 12p13.33 including RAD52 influences squamous cell lung carcinoma risk
Authors: Shi Jianxin , Chatterjee Nilanjan , Rotunno Melissa , Wang Yufei , Pesatori Angela C. , Consonni Dario , Li Peng , Broderick Peter , Henrion Marc , Eisen Timothy , Wang Zhaoming , Chen Wei , Dong Qiong , Albanes Demetrius , Thun Michael , Spitz Margaret , Bertazzi Pier Alberto , Caporaso Neil , Chanock Stephen , Amos Christopher , Houlston Richard , Landi Maria Teresa
Published: August 2012

While lung cancer is largely caused by tobacco smoking, inherited genetic factors play a role in its etiology. Genome-wide association studies (GWAS) in Europeans have robustly demonstrated only three polymorphic variations influencing lung cancer risk. Tumor heterogeneity may have hampered the detection of association signal when all lung cancer subtypes were analyzed together. In a GWAS of 5,355 European smoking lung cancer cases and 4,344 smoking controls, we conducted a pathway-based analysis in lung cancer histologic subtypes with 19,082 SNPs mapping to 917 genes in the HuGE-defined “inflammation” pathway. We identified a susceptibility locus for squamous cell lung carcinoma (SQ) at 12p13.33 (RAD52, rs6489769), and validated it in three independent samples totaling 3,359 SQ cases and 9,100 controls (odds ratio=1.20, Pcombined=2.3×10−8). The combination of pathway-based approaches and information on disease specific subtypes can improve the identification of cancer susceptibility loci in heterogeneous diseases.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2931. doi:1538-7445.AM2012-2931
Abstract 2942: RKI-1447, a potent ROCK inhibitor with anti-tumor and anti-invasive activities in breast cancer
Authors: Patel Ronil A. , Forinash Kara D. , Pireddu Roberta , Sun Ying , Martin Mathew P. , Zhu Jin-Yi , Alexander Brian G. , Schonbrunn Ernst , Lawrence Nicholas J. , Sebti Said M.
Published: August 2012

Rho-associated kinases 1 and 2 (ROCKs) are intimately involved in metastasis and this prompted the development of ROCK inhibitors (RKIs) as anti-metastatic agents. Here, we describe the development of RKI-1447 which inhibits ROCK 1 and 2 potently in vitro (IC50s; 14 and 6 nM, respectively) and suppresses the phosphorylation of ROCK substrates MLC2 and MYPT1 in human breast cancer cells (IC50; 100 nM). The crystal structure of the RKI-1447-ROCK1 complex reveals that RKI-1447 binds the hinge region in the ATP binding site. RKI-1447 is highly selective and does not affect the phosphorylation levels of Akt, Erk, Mek and S6. RKI-1447 is also highly selective at inhibiting ROCK-mediated cytoskeleton re-organization (actin stress fiber formation) following LPA stimulation, but does not affect PKA-meditated lamelipodia and filopodia formation following PDGF and bradykinin stimulation, respectively. RKI-1447 inhibits migration, invasion and anchorage-independent tumor growth of breast cancer cells. A structurally-related analog RKI-1313 that is inactive against ROCKs in vitro (IC50 > 10 µM) has little effects on migration, invasion and anchorage-independent growth. Finally, RKI-1447 is highly effective at inhibiting the growth of ErbB2-driven breast tumors in a transgenic animal model.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2942. doi:1538-7445.AM2012-2942
Abstract 2948: The role of the RNA binding protein LIN28B in neuroblastoma
Authors: Powers John , Spina Catherine , Collins James , Daley George
Published: August 2012

Neuroblastoma is the most frequent extracranial solid tumor in children, accounting for almost 9% of all childhood cancers and close to 15% of childhood cancer deaths. Amplification of MYCN occurs in up to 40% of neuroblastomas, and is a marker of very poor prognosis. Current treatment strategies for MYCN amplified tumors are ineffective and in desperate need of new therapeutic avenues. The LIN28 A and B RNA binding proteins negatively regulate the let-7 family of pro-differentiation/ tumor suppressor miRNAs, enhance the translation of mRNA binding partners, and are emerging as novel onco-proteins. We show here that LIN28B is highly expressed in neuroblastoma, both in human neuroblastoma cell lines and in neuroblastoma patient samples, with an expression pattern similar to MYCN. The LIN28 proteins have been shown to directly regulate MYC, and knockdown of LIN28B in MYCN-amplified human neuroblastoma cells results in markedly reduced MYCN expression, impaired growth, greater differentiation, and reduced tumor size in mouse xenograft studies, indicating an important functional link between LIN28B and MYCN. Through LIN28B/mRNA co-immunoprecipitation we have discovered that LIN28B binds MYCN mRNA, suggesting a novel mechanism of LIN28B contribution to MYCN activity in high-risk neuroblastoma. In addition, we have also discovered that LIN28B is acetylated within its RNA binding domain, and mutational studies have suggested that modulating this post-translational modification may destabilize LIN28B protein stability. Through proteomic analysis of LIN28B -associated proteins, we have identified an acetyl-transferase as a candidate drug target for disruption of the LIN28B/MYCN oncogenic pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2948. doi:1538-7445.AM2012-2948
Abstract 2954: TWIST1 is a critical mediator of KRAS mutant tumorigenesis in human non-small cell lung cancer
Authors: Burns Timothy F. , Dobromilskaya Irina , Murphy Sara C. , Gajula Rajendra P. , Aziz Khaled , Cho Yoon-Jae , Tran Phuoc T. , Rudin Charles M.
Published: August 2012

A large fraction of non-small cell lung cancers (NSCLC) have mutant KRAS, which is associated with poor response to current cytotoxic therapy and a poor prognosis. Although the KRAS signaling pathway has been well characterized, no current therapies target this critical oncogene. Several studies have demonstrated that bypass of senescence in Kras-mediated adenocarcinoma mouse models is essential for tumorigenesis. Therefore, activation of senescence in KRAS mutant NSCLC may be an effective therapeutic strategy. We recently demonstrated that the basic helix loop helix transcription factor Twist1 cooperates with mutant Kras to induce lung adenocarcinoma in transgenic mouse models and that inhibition of Twist1 in these models led to activation of Kras-induced senescence and tumor stasis. In the current study, we examine the role of TWIST1 in KRAS mutant human NSCLC. Silencing of TWIST1 in multiple KRAS mutant NSCLC cell lines resulted in dramatic growth inhibition and either reactivation of oncogene-induced senescence or in some cases, apoptosis. Similar effects were also observed in four KRAS wild type lines, including cell lines with key driver mutations including a cell line with an activating EGFR mutation and a cell line with c-Met amplification. Gene set enrichment analysis of NSCLC cell lines after silencing of TWIST1 revealed a striking cell cycle arrest gene signature. Growth inhibition by silencing of TWIST1 was independent of p53 or Rb/p16 mutational status. Furthermore, activation of oncogene-induced senescence by TWIST1 silencing did not require previously defined mediators of senescence, p21 and p27, nor could this phenotype be rescued by overexpression of SKP2. To extend these observations in vivo, TWIST1 was silenced in both KRAS mutant and wildtype cell lines and these cells were implanted in NOD-SCID mice to assess tumor formation. Interestingly, silencing of TWIST1 in xenograft models preferentially inhibited KRAS mutant tumor formation suggesting that TWIST1 plays a critical in mediating KRAS tumorigenesis. Finally, inducible silencing of TWIST1 resulted in significant growth inhibition of established xenograft KRAS mutant tumors. Together these findings suggest TWIST1 is essential for the establishment and maintenance of KRAS mutant NSCLC tumors and silencing of TWIST1 in KRAS mutant NSCLC represents a novel and promising therapeutic strategy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2954. doi:1538-7445.AM2012-2954
Abstract 2956: High throughput RNAi screening of synthetic lethal genes interacting with the common TP53 mutation R175H
Authors: Imai Hiroo , Kato Shunsuke , Sakamoto Yasuhiro , Kakudo Yuichi , Takahashi Shin , Shimodaira Hideki , Ishioka Chikashi
Published: August 2012

The R175H mutation of p53 which account for approximately 6% of the missense mutations of identified in human cancer is one of the most common mutations, and cancer cells with this mutation stably express the R175H protein in the nucleus. Targeting R175H overexpressing cells by synthetic lethality is one of the extremely effective strategies for cancer therapy. To identify the synthetic lethal gene interacting with R175H, we conducted high throughput screening using a tetracycline-inducible R175H expression system in SF126 cells and comprehensive shRNA library carried by lentivirus. We identified 906 candidate gene suppressions that may lead to accelerated cell growth inhibition in the presence of R175H (p<0.05, n=3). Among these, we selected 50 genes (21 genes from the group with the smallest p-values, 20 genes from the group with the largest fold change, and 9 genes reproduced by different siRNA sequences) for further validation testing. By transfection of siRNA of these candidate genes into five R175H expressing cell lines and four TP53-null cell lines, we selected five candidate genes that significantly lead R175H expressing cells to strong cell growth inhibition. Inhibitor of differentiation 1 (ID1) was one of the five candidate genes, and its suppression by siRNA resulted in the acceleration of growth inhibition in cell lines expressing endogenous R175H; however, this was not observed in TP53-null cell lines. The transient expression of R175H in TP53-null cell lines (PC3) and suppression of ID1 and/or TP53 R175H in cell lines with endogenous R175H revealed that cell growth inhibition by ID1 suppression depended on the expression of R175H, and not that of other common p53 mutants (e.g., R273H). Flow cytometric analysis exhibited that ID1 suppression resulted in G1 arrest, and the arrest was accelerated by the expression of R175H. In conclusion, ID1 is a synthetic lethal gene that interacts with R175H and is considered to be a novel molecular target for cancer therapy in R175H expressing cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2956. doi:1538-7445.AM2012-2956