bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4507: Discovery of a novel single chain ribosome inactivating protein that selectively kills human melanoma cells
Authors: Cheung Melissa , Revers Leigh , Perampalam Subodini , Wei Xin , Kiarash Reza , Green David , Green Erin , Gariepy Jean
Published: February 2011

Few treatment options exist for patients with metastatic melanoma. The standard treatment, dacarbazine (DTIC), shows low response rates ranging from 15% to 25 % with an 8-month median survival time. The development of targeted therapeutics with novel mechanisms of action may improve patient outcome. Ribosome-inactivating proteins (RIPs) such as Shiga-like Toxin 1 (SLT-1) represent powerful scaffolds for developing selective anticancer agents. Here we report the discovery and properties of a single chain, ribosome-inactivating protein (scRIP), termed SLT-1AIYSNKLM that selectively targets and kills human melanoma cells. SLT-1AIYSNKLM was identified following the purification and screening of cytotoxic A chain mutants derived from a combinatorial SLT-1A library This scRIP was shown to selectively kill 7 out of 8 human melanoma cell lines while being ineffective at killing non-melanoma cell lines. Biodistribution and imaging studies of radiolabeled SLT-1AIYSNKLM in SCID mice bearing a human melanoma xenograft indicate that it readily accumulates at the tumor site. Furthermore, the co-administration of SLT-1AIYSNKLM [i.v.] with DTIC [i.p.] resulted in tumor regression and greatly increased animal survival in this mouse xenograft model in comparison to DTIC or SLT-1AIYSNKLM treatments alone. SLT-1AIYSNKLM is stable in serum and binds to human melanoma 518-A2 cells with a dissociation constant of 18 nM. The intravenous administration of SLT-1AIYSNKLM resulted in modest immune responses following repeated i.v. injections in immunocompetent CD1mice. These results suggest that scRIP templates can be evolved to target cancer cells and in the case of SLT-1AIYSNKLM can specifically kill human melanoma cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4507.
Abstract 451: HIF-1 alpha silencing in MDA-MB-231 human breast cancer cells alters choline phospholipid metabolism
Authors: Shah Tariq , Krishnamachary Balaji , Wildes Flonne , Bhujwalla Zaver M.
Published: February 2011

Hypoxia-inducible factor-1 (HIF-1) over-expression has been associated with an increased patient mortality rate in many cancer types including breast cancer. Suppression of HIF-1 gene expression has been shown to inhibit tumor growth. Here we have studied the effect of HIF-1 silencing on the metabolism of MDA-MB-231 cells using a magnetic resonance (MR)- compatible cell perfusion assay. Previous studies have identified choline kinase (Chk), the enzyme that converts choline to phosphocholine (PC), and the resulting increase of PC and total choline (tCho) as markers of an aggressive phenotype. We found that HIF-1 silencing resulted in significantly reduced Chk expression together with reduced tCho and PC, compared to parental cells.

The sequence for shRNA against HIF-1α was cloned into a lentivirus vector with a green fluorescent protein (GFP) reporter construct (pRRL-pGK-GFP). Viral supernatant preparation and transduction of MDA-MB-231 breast cancer cells was performed following standard protocol. Transduced cells were validated for HIF-1α knock-down by western blots and by quantitative real-time polymerase chain reaction (q RT-PCR). Cell perfusion studies were performed using an MR-compatible perfusion assay to determine intracellular levels of metabolites using 1H and 31P MR spectroscopy (MRS). Experiments were performed in triplicates. The Mann Whitney-U test was used to determine statistical significance (p <0.05).

HIF-1α protein expression increased following treatment with 200μM of the hypoxia mimetic CoCl2 in parental MDA-MB-231 cells but not in cells transduced with HIF-1α shRNA. Reduced expression of Chk in HIF-1α silenced cells was observed following CoCl2 treatment, while its expression was induced in parental cells. Quantitative data from 1H and 31P MRS showed significantly reduced levels of tCho (p <0.05) and PC (p < 0.01) in HIF-1α silenced cells compared to parental MDA-MB-231 cells, confirming that silencing of HIF-1α reduced levels of choline containing metabolites by reducing Chk expression. We previously observed that Chk is up regulated under hypoxia and have established a HIF-1 binding site on the Chk promoter. The reduction of choline metabolites in HIF-1α silenced cells further confirms the role of HIF-1α in the regulation of Chk. The reduction of Chk, total choline and PC levels in HIF-1α silenced cells are also typical of a less aggressive metabolic phenotype.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 451.
Abstract 4511: LY2801653 treatment increases survival of mice bearing H441 orthotopic lung tumors
Authors: Wu Wenjuan , Bi Chen , Uhlik Mark T. , Pomeroy Julie A. , Gao Hong , Credille Kelly M. , Walgren Richard A. , Shih Chuan , Yingling Jonathan M. , Yang Wei
Published: February 2011

Lung cancer is the leading cause of cancer-related death for both men and women in the world. c-Met receptor tyrosine kinase (RTK) signaling pathway has been implicated in tumor growth, angiogenesis, and metastasis. Sustained activation, over-expression, or mutation of c-Met is associated with poor prognosis in several tumors, including NSCLC. Therefore, c-Met is emerging as a novel target of therapeutic potential for lung cancer. We have discovered and developed a novel, ATP competitive, and orally active small molecule inhibitor of c-Met, LY 2801653. It is a potent inhibitor of c-Met phosphorylation in vivo, and demonstrated anti-tumor activity in several xenograft tumor models. In the current study, we evaluated the efficacy of LY2801653 in both c-Met dependant and c-Met independent NSCLC cells in vitro and in vivo orthotopic lung models that recapitulated the local and regional growth pattern seen in lung cancer patients. In c-Met dependant H441 model, LY2801653 demonstrated the significant inhibition of both primary tumor (90% inhibition) and metastasis (65% inhibition of lymph node and 70% inhibition of chest wall); whereas in c-Met independent H1299 model, LY281653 only inhibited primary tumor growth (70% inhibition). The benefit of LY2801653 treatment was further demonstrated in the survival of mice bearing H441 lung tumors. Treatment with LY2801653 significantly increased the survival of mice to 192% compared to that in the vehicle treated mice. The anti-tumor and/or anti-metastasis mechanism of LY2801653 was also investigated. These results demonstrated therapeutic potential of LY2801653 in the treatment of lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4511.
Abstract 4512: The novel HSP90 inhibitor, PF-04929113, inhibits AR activity and osteoclastogenesis and delays castrate-resistant LNCaP prostate cancer tumor growth
Authors: Lamoureux Francois , Yin Min-Jean , Zoubeidi Amina , Gleave Martin E.
Published: February 2011

Introduction and Objective: Prostate cancer responds initially to anti-androgen therapies, however, progression to castration resistant disease frequently occurs. Consequently there is an urgent need for novel therapeutic agents that can prevent the emergence of the castration resistant form of disease. Heat shock protein (HSP) 90 is a molecular chaperone involved in the maturation and stability of the Androgen Receptor (AR). In this study, we assessed the in vitro and in vivo antitumor properties of a novel synthetic HSP90 inhibitor, PF-04928473 in vitro and PF-04929113 in vivo, in prostate cancer and bone metastasis development.

Methods: The effects of the HSP90 inhibitor were evaluated in vitro on LNCaP, C4-2, PC3 and DU145 cell growth and apoptosis. AR transactivation and other biochemical assays studied AR/HSP90 interaction. The consequence of HSP90 therapy in vivo was evaluated in athymic mice bearing castration resistant LNCaP xenografts. The consequence of PF-04928473 therapy on bone metastasis was studied using a osteoclastogenesis in vitro assay.

Results: In our panel of prostate tumor cell lines, PF-04928473 inhibited cell growth in a dose-dependent manner (IC50 ± 30nM) and induced apoptosis with an increase of sub-G1 fraction and PARP cleavage. These biologic events were accompanied by decreased expression of AR and PSA, AR transactivation, inhibition of Akt and Erk activation, and modulation of HSP expression. When administered orally 3 times/week (50mg/kg) to mice bearing castration resistant LNCaP tumors, PF-04929113 significantly inhibited tumor growth by 160% and prolonged survival compared to controls, but a small reduction in total bodyweight was observed. In contrast to 17-AAG, the novel PF-04928473 compound was not observed to activate src but did block osteoclast differentiation in vitro.

Conclusions: Targeting HSP90 using PF-04928473 and PF-04929113 inhibited castration resistant LNCaP tumor growth in vitro and in vivo in part through a mechanism involving disruption of the AR signaling axis and appears to inhibit bone metastasis by blocking osteoclastogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4512.
Abstract 4514: Proteasome inhibition causes regression of leukemia in part through regulation of forkhead tumor suppressors
Authors: Singh Amrik , Ye Min , Song Keli , Bucur Octavian , Khosravi-Far Roya
Published: February 2011

BCR-ABL plays an essential role in the pathogenesis of chronic myeloid leukemia (CML) and some cases of acute lymphocytic leukemia (ALL). Although ABL kinase inhibitors have shown great promise in the treatment of CML, the persistence of residual disease and the occurrence of resistance have prompted investigations into the molecular effectors of BCR-ABL. Here, we show that BCR-ABL stimulates the proteasome-dependent degradation of members of the forkhead family of tumor suppressors in vitro, in an in vivo animal model, and in samples from patients with BCR-ABL-positive CML or ALL. As several downstream mediators of BCR-ABL are regulated by the proteasome degradation pathway, we also show that inhibition of this pathway, using bortezomib, causes regression of CML-like disease. Bortezomib treatment led to inhibition of BCR-ABL-induced suppression of FoxO proteins and their proapoptotic targets, tumor necrosis factor-related apoptosis-inducing ligand and BIM, thereby providing novel insights into the molecular effects of proteasome inhibitor therapy. We additionally show sensitivity of imatinib-resistant BCR-ABL T315I cells to bortezomib. Our data delineate the involvement of FoxO proteins in BCR-ABL-induced evasion of apoptosis and provide evidence that bortezomib is a candidate therapeutic in the treatment of BCR-ABL-induced leukemia.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4514.
Abstract 4519: Small cell lung cancers lack expression of argininosuccinate synthase (ASS) and are sensitive to arginine deprivation using arginine deiminase-PEG20 (ADI-PEG20)
Authors: Kelly Marcus P. , Jungbluth Achim A. , Wu Bor-Wen , Bomalaski John , Ritter Gerd , Old Lloyd J.
Published: February 2011

Various tumor types have been shown to lack expression of the enzyme argininosuccinate synthase (ASS) that is required for the synthesis of arginine and thus rely on exogenous sources for protein synthesis requirements. These tumors may be sensitive to arginine deprivation, and the absence of ASS expression may serve as a biomarker for this sensitivity. Arginine deiminase (ADI) is a microbial enzyme that has been shown to efficiently lower peripheral blood arginine. Its therapeutic efficacy has been previously explored in the treatment of melanoma and hepatocellular cancer in early phase clinical trials but clinical efficacy in these tumor types has been limited. However, other tumor types lacking ASS may be more sensitive to arginine depletion. We have investigated ASS expression in human small cell lung cancer (SCLC) tumor tissue by immunohistochemistry (IHC) and have so far found that about 43% (7/16) of SCLC tumors were negative for ASS. SCLC has a robust initial response to chemotherapy but the majority of cases relapse and there remain limited options in the treatment of refractory disease. Based on the IHC findings and the need for novel therapies in recurrent SCLC, we explored the effects of pegylated ADI (ADI-PEG20) mediated arginine deprivation in SCLC in vitro and in vivo. We screened a panel of 10 human SCLC cell lines for ASS mRNA and protein expression by Real Time PCR and Western blot analysis. Little or no ASS was observed in 50% (5 of 10) of the SCLC cell lines examined and this frequency is approximately equivalent to that found in the SCLC tumor tissues. In cell proliferation assays a clear correlation between expression of ASS and sensitivity to ADI-PEG20 was detected. Biochemical analysis of the mechanism of ADI-PEG20 induced cell death in ADI sensitive cell lines revealed induction of autophagy and cell death through caspase independent mechanisms. Assessment of ADI-PEG20 activity in vivo using mice bearing SCLC xenografts demonstrated that ADI-PEG20 treatment of ASS negative SCLC xenografts caused significant and dose dependent inhibition of tumor growth, while no effect was observed with placebo controls. These results suggest a role for ADI-PEG20 in the treatment of SCLC, and a clinical trial exploring this treatment in patients with ASS negative SCLC by IHC has been initiated.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4519.
Abstract 4521: Discovery of novel small molecule inhibitors of the antiapoptotic protein Mcl-1 through high-throughput screening approach
Authors: Liu Meilan , Shen Chenxi , Larsen Martha , Yang Chao-Yie , Qiu Su , Tomita York , Krajewski Krzysztof , Roller Peter P. , Stuckey Jeanne , Wang Shaomeng , Nikolovska-Coleska Zaneta
Published: February 2011

Myeloid cell leukemia (Mcl-1) is a multidomain, anti-apoptotic protein, member of the Bcl-2 family proteins, an important survival factor for many cancers. Mcl-1 has a critical and distinct role(s) in maintaining cell survival and emerging as an independent and promising therapeutic target.

Through high throughout screening (HTS) of 53,300 structurally diverse synthetic organic compounds, we have discovered a number of novel inhibitors of Mcl-1. The hits identified by HTS were evaluated in a series of complementary biochemical, biophysical, functional and cellular assays to eliminate false positives and to determine the specificity and mechanism of action of these new compounds and 23 compounds were found to be inhibitors of Mcl-1. The most promising compounds, 59 and 62, have diverse chemical scaffolds. We have shown that these small molecule inhibitors bind to the BH3 binding site in Mcl-1 with IC50 values of 1,200 nM and 200 nM, respectively, and compete with BH3 peptides derived from Bid, Bim, or Noxa proteins. They bind to the Mcl-1 protein showing selectivity over two other Bcl-2 family members, Bcl-2 and Bcl-xL. NMR spectroscopy shows that 59 and 62 bind to the same BH3 domain of Mcl-1 as the Bim BH3 peptide. These initial lead compounds antagonize Mcl-1 on the functional level and they induce release of cytochrome c, inhibit cell growth and induce apoptosis in pancreatic and melanoma cancer cells with high levels of Mcl-1. We have tested several analogues of 59 and 62, both synthetic and commercially available, and established initial structure-activity relationships. One of the compounds tested (77), an analogue of 59, has improved binding affinity to Mcl-1 protein, as well as potent activity in inhibition of cell growth in cancer cells. Furthermore, by using murine embryonic fibroblasts (MEFs), wild type and deficient in both Bax and Bak (double knock out), it was demonstrated that the cytotoxic activity and induction of apoptosis by several analogues of the lead compound 59, depend on Bax and/or Bak, suggesting that they function as BH3 mimetics.

Collectively, these findings provide good promise for chemical modifications of the new identified lead compounds, 59 and 62, and their further optimization toward developing a new class of anticancer drugs, Mcl-1 inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4521.
Abstract 4522: Oncogenic stress-induced cell death following Imatinib deprivation in Bcr-Abl overexpressing Imatinib-resistant ALL cells
Authors: Dengler Michael A. , Staiger Annette M. , Gutekunst Matthias , Aulitzky Walter E. , van der Kuip Heiko
Published: February 2011

Imatinib resistance is a major problem in treatment of Bcr-Abl positive leukemias, particularly in patients with ALL and advanced CML. One of the major mechanisms of this resistance is overexpression of Bcr-Abl.

We investigated the effects of Imatinib deprivation in Bcr-Abl overexpressing Imatinib-resistant ALL cell lines. Removal of Imatinib from culture medium led to a huge induction of Bcr-Abl autophosphorylation and concomitant overstimulation of PI3K-, MAPK-, and JAK/STAT signalling leading to an elevated cell size and cellular protein content. Massive induction of cell death was then observed at later time points (48 hours after Imatinib deprivation) accompanied by loss of outer and inner mitochondrial membrane integrity. Using a protein kinase inhibitor library, we identified inhibitors of glycogen synthase kinase-3 (GSK3) and p38-MAPK as the most potent compounds which completely prevented induction of cell death upon removal of Imatinib whereas the same inhibitors had synergistic effects with Imatinib in Imatinib-sensitive ALL cells. In contrast to GSK3- and p38, inhibition of PI3K had no effect on oncogenic stress upon Imatinib withdrawal in the resistant clones.

Importantly, oncogenic stress-induced cell death could not be blocked by the pan-caspase inhibitor z-VAD-fmk whereas the RIP1 inhibitor Necrostatin partially rescued the cells upon Imatinib deprivation. We also detected a posttranslational modification of RIP1 upon Imatinib withdrawal that was completely absent in cells pre-treated with GSK3- or p38 inhibitors indicating a central role of RIP1 for oncogenic stress-induced cell death. In conclusion, we found a massive induction of a necroptosis-like cell death in Bcr-Abl overexpressing ALL cells as a consequence of oncogenic stress upon Imatinib deprivation. GSK3 and p38 turned out to play the most prominent role for oncogenic stress induced cell death. These data implicate that a discontinuous treatment with Imatinib (periods of Imatinib treatment followed by short periods without Imatinib) may prevent the appearance of cell clones with Bcr-Abl overexpression.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4522.
Abstract 4524: Targeting Bcl-2 family proteins in adult T-cell leukemia/lymphoma: in vitro and in vivo effects of a novel Bcl-2 family inhibitor, ABT-737
Authors: Kunami Naoko , Ishitsuka Kenji , Yotsumoto Fusanori , Ishikawa Chie , Katsuya Hiroo , Sawada Shigeki , Tanji Hiroe , Takeshita Morishige , Mori Naoki , Miyamoto Shingo , Kuroki Masahide , Tamura Kazuo
Published: February 2011

Adult T-cell lymphoma/leukemia (ATLL) is a T-cell malignancy caused by the human T-lymphotrophic virus type I (HTLV-I), and its therapeutic outcome still remains extremely poor. Therefore, novel therapeutic strategies are needed to improve treatment outcomes. In this study, we elucidated the therapeutic potential of targeting the anti-apoptotic Bcl-2 family proteins for the treatment of ATLL using ABT-737 (Abbott Laboratories, Abbott Park, IL, USA), a small molecule inhibitor of Bcl-2, Bcl-XL and Bcl-w. We first validated the rationale of this study by immunohistochemically assessing the expression of Bcl-2 family proteins in 25 lymph-node specimens derived from ATLL patients. The Bcl-2 and/or Bcl-XL proteins were expressed in 80% of specimens. We next examined the cytotoxicity of ABT-737 against three ATLL cell lines by the Colorimetric method. ABT-737 significantly inhibited growth of MT-1, MT-2 and HuT 102 cells with concentrations of 50 percent inhibition of 2.4, 0.23 and 0.008μM at 72 h, respectively. We then tried to clarify the mechanism of growth inhibition induced with ABT-737 using MT-1 and MT-2 cells. ABT-737 induced apoptosis in both cells with cleavage of caspases 9 and 3, and PARP. ABT-737 also induced apoptosis in fresh tumor cells derived from patients with ATLL. We also tested if ABT-737 enhances the cytotoxicity induced by conventional chemotherapeutic agents or novel agents. The interactions between them were evaluated using the Chou-Talalay method. ABT-737 synergistically enhanced the cytotoxicity and apoptosis induced by doxorubicin, vincristine or etoposide and bortezomib or suberolyanilide hydroxamic acid, which are current key drugs and promising candidates for the treatment of ATLL, respectively. Finally, we investigated the growth inhibition of ABT-737 in ATLL-xenografted mice. The mean tumor volume and weight, and mean serum level of soluble interleukin-2 receptor α at day 21 of the treated mice with ABT-737 (100mg/kg/day) were significantly lower than those of vehicle-treated mice. Moreover, massive induction of apoptosis was observed in tumors treated with ABT-737 by the TUNEL assay. These results suggest that the use of ABT-737, either alone, or in combination with other conventional cytotoxic and novel drugs, represents a promising novel targeted approach to overcome drug resistance and to improve patient outcome in ATLL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4524.
Abstract 4525: Targeting ROS to kill cisplatin-resistant cells
Authors: Wangpaichitr Medhi , Wu Chunjing , Kuo M.t. , You Min , Dinh Vy , Feun Lynn , Savaraj Niramol
Published: February 2011

Cisplatin (CP) resistance remains a major problem in the treatment of both small cell and non small cell lung cancer. We have previously shown that inhibiting mTOR can restore CP sensitivity; however, not all CP resistant cell lines are sensitive to mTOR inhibitor. Our findings have led us to search for an alternative target in these CP resistant cells. We have discovered that CP resistant cells share one common biochemical parameter which is increased reactive oxygen species (ROS) when compared to normal cells and their parental cells counterpart. Thus, further increased ROS in these CP resistant cells can push them beyond their tolerance limit which ultimately leads to cell death. We have found that increased expression of NADPH oxidase 4 (NOX4) and lower levels of thioredoxin (Trx) correlate with the high levels of ROS seen in CP resistant cell lines. Using elesclomol (N′1, N′3-dimethyl-N′1, N′3- bis [phenylcarbonothioyl] propanedihydrazide (formerly STA-4783, provided by Synta Pharmaceuticals)), an agent which is known to increase ROS, we demonstrated that elesclomol can increase H2O2 levels in CP resistant lung cancer cell lines (CP-R). Moreover, elesclomol is also significantly more cytotoxic toward CP-R with the ID50 dosage of 4-10 fold less than their parental cells (PC) counterpart and normal cells, BJ-1 (see table below). The percentage of apoptosis is also significantly higher in CP-R (65%) vs. PC (3%). The cytotoxic effect of elesclomol in CP-R is accompanied by further decrease in Trx and glutathione (GSH) antioxidant systems, while opposite results were found in PC and normal cells. This cytotoxic effect can be reversed by an antioxidant, N-acetylcysteine (NAC, 0.1mM). Furthermore, we have also found that elesclomol also increased intracellular CP and hence enhanced CP sensitivity in CP-R cells. We conclude that elesclomol is highly effective in CP resistant cells which express high basal levels of ROS and should be considered for treatment of CP resistant tumor.ID50 Dosage of Elesclomol in Parental (PC) vs. Cisplatin Resistant (CP-R) Lung Cancer Cell Lines SCLC1(PC)SCLCSR2(CP-R)SCLCB(PC)SCLCBC (CP-R)NSCLCS(PC)NSCLCSC(CP-R)BJ1Elesclomol(nM)50+/−2.55+/−0.541+/−3.89+/−1.259+/−4.610+/−2.265+/−5.5

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4525.
Abstract 4527: p53-Reactivating Small Molecules Induce Apoptosis in Head and Neck Cancer
Authors: Roh Jong-Lyel , Kang Sung Koo , Kim Myung Sook , Cho Yong Gu , Califano Joseph A. , Sidransky David , Koch Wayne M.
Published: February 2011

Novel small molecules have been reported to restore the p53 tumor suppressor function inducing cell cycle arrest and apoptosis. The p53-targeting therapy may overcome the resistance to chemotherapeutic agents. This study evaluated whether small molecules induce p53-dependent apoptosis in head and neck squamous cell carcinoma (HNSCC) lines. PRIMA-1, CP-31398, RITA, and nutlin-3 were tested in 6 HNSCC cell lines with different p53 status and MDM2 expression levels. Cell growth, viability, cell cycle, and apoptosis after the treatment or combined treatment with common chemotherapeutic agents were assessed. The p53 reactivation was observed in mutant TP53-carrying cell lines by PRIMA-1 or CP-31398 treatment and in wild-type TP53-carrying cell lines by nutlin-3 treatment. The cell cycle arrest and apoptosis by the small molecules was associated with up-regulation of p21, Bax, and cleaved caspase-3. PRIMA-1 or CP-31398 induced also significant apoptosis in cell lines without p53 protein expression. Nutlin-3 or RITA showed maximal suppression in tumors with MDM2-induced tumor degradation. The small molecules enhanced the antitumor activity of the cell lines with a combination of cisplatin, 5-fluorouracil, paclitaxel, or erlotinib. The small molecules effectively restored p53 tumor suppressive function in HNSCC with mutant or wild-type p53. The p53 reactivating agents may be used for HNC with a combination of commonly-used chemotherapeutic agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4527.
Abstract 4530: The anti-tumor effect of MDM2 antagonist nutlin-3 in gastric cancer cell in vitro and in vivo
Authors: Endo Shinji , Suzuki Hideo , Hirai Sachiko , Hyodo Ichinosuke , Yamato Kenji
Published: February 2011

Purpose: The mortality of gastric cancer is still high accounting for an estimated 50,000 deaths in Japan. The chemotherapies based on fluoropyrimidine and platinum complexes are widely used for unresectable advanced gastric cancer, however, development of new strategies including molecular targeting therapies are urgently required to obtain further effectiveness. Recent studies demonstrate that 70% of gastric cancers has wild-type p53 gene and its function thought to be inhibited by over-expression of murine double minute 2 (MDM2), a regulator of p53 turnover by binding p53 and acting as a ubiquitin E3 ligase. Nutlin-3 is a small-molecule MDM2 antagonist that efficiently activates p53 and its tumor suppresser function has been shown in retinoblastoma and hematological malignancy but not in gastrointestinal carcinoma. In this study, we investigated the antitumor effects of nutlin-3 in gastric cancer cells in combination with 5-fluorouracil or cisplatin in vitro and in vivo.

Experimental Design: Human gastric cancer cell lines carrying wild-type (4 cell lines) or mutated p53 gene (3 cell lines) were incubated with nutlin-3 alone or combination with 5-fluorouracil or cisplatin in time dependent manner. Cell viability was calculated by WST assay. Western blot analysis for MDM2 and p53 are also performed to investigate protein expression. In vivo study, mice xenografted gastric cancer cells were treated with nutlin-3 alone or combination with 5-fluorouracil intraperitoneally. The tumor size was measured and histochemistry was done after 3 weeks administration.

Results: Nutlin-3 showed strong cytotoxicity in gastric cancer cells carrying wild-type p53 gene not mutated p53 gene, regardless of expression level of MDM2 protein. Anti-tumor effect of Nutlin-3 was also observed in xenografted mice model. Histochemical analysis indicated nutlin-3 induced apoptotic cell death in tumor tissue. Furthermore, combined treatment with nutlin-3 and 5-fluorouracil or cisplatin revealed enhanced cytotoxicity in gastric cancer cells with wild-type p53 gene.

Conclusions: Our results present new option in exploiting reactivation of p53 as what we believe to be a novel and highly selective treatment for gastric cancer patients with wild-type p53 gene.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4530.
Abstract 4532: Nucleolin inhibits Hdm2-mediated p53 ubiquitination using multiple interactions
Authors: Bhatt Purvi , d'Avout Claire , Kane Naiomi S. , Borowiec James A. , Saxena Anjana
Published: February 2011

Nucleolin is a multifunctional abundant nucleolar protein whose transcriptional expression is trans-activated by the proto-oncogene c-myc during exponential cellular growth. This non-ribosomal protein has defined roles in ribosomal RNA processing and transcriptional regulation of various genes including rRNA. Following cellular stress, nucleolin has been shown to inhibit chromosomal replication and to relay nucleolar stress signals mediated by its sub-nuclear re-localization. Thus, nucleolin has been demonstrated to have both positive and negative effects on cell proliferation. We have previously demonstrated that nucleolin binds to the p53-antagonist Hdm2 and inhibits Hdm2-mediated degradation of p53 albeit independent of the ARF (Alternate Reading Frame) tumor suppressor protein. Nucleolin also reduces Hdm2 protein levels by an unknown mechanism when over-expressed in cells to levels found in a variety of cancer cells. Here we have delineated that multiple domains of both nucleolin and Hdm2 are involved in distinct nucleolin-Hdm2 interactions in unstressed cells. Our data indicates that the nucleolin N-terminus as well as the central RNA-binding domain (RBD) are predominantly involved in binding to Hdm2, as determined by Far-Western as well as GST-binding assays in vitro. While the N-terminus of nucleolin was found associated with the Hdm2 RING domain, the nucleolin RBDs robustly bound to the NLS/NES (nuclear localization and export signals) domain of Hdm2. The C-terminal GAR (Glycine-Arginine Rich) domain of nucleolin, shown previously to be essential for association with p53, did not bind Hdm2 yet was found to stimulate Hdm2-mediated p53-ubiquitination. Conversely, the nucleolin RBD that strongly interacted with Hdm2 was found to inhibit the Hdm2 E3 ligase activity against p53, leading to p53 stabilization. There was no significant effect of over-expression of nucleolin or its various domains on Hdm2-autoubiquitination in cells. Similarly, the phosphorylation status of nucleolin did not significantly influence its binding to Hdm2. As might be expected from a key rRNA processing factor, our findings suggest that the activity of nucleolin towards Hdm2 can be modulated to yield either p53 up- or down-regulation. Our studies can aid in the future design of small molecule-based cancer therapeutics that can stimulate the wild-type p53 checkpoint in variety of cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4532.
Abstract 4534: A novel and potent small molecule antagonist of HDM2, SCH 1450206, activates the p53 pathway with mechanism-based activity
Authors: Liu Suxing , Mirza Asra , Wang Xiaoying , Lipari Philip , Lin Yinghui , Bogen Stephane , Ma Yao , Doll Ronald , Shipps Gerald , Seidel-Dugan Cynthia , Hicklin Daniel J. , Bishop W. Robert , Wang Yaolin
Published: February 2011

p53 is an attractive therapeutic target in oncology since aberrant regulation of p53 expression is associated with cancer development and progression. HDM2 is a primary negative regulator of p53 function in cells. The blockade of the p53-HDM2 interaction presents an attractive approach for development of drugs against tumors expressing wild-type p53. Here we report a novel and potent small molecule antagonist of HDM2, SCH 1450206. It binds selectively to the HDM2 protein with high affinity, with weak affinity to HDMX protein. SCH 1450206 induced dose- and time-dependent stabilization of p53 protein and its downstream targets in several human cancer cell lines with wild-type p53, but not in cell with p53 gene deletion. SCH 1450206-induced stabilization of p53 led to distinct changes in expression of p53 target genes regulating apoptosis and cell cycle checkpoints. Inhibition of cell proliferation and induction of apoptosis were surveyed in a panel of human tumor cell lines following SCH 1450206 treatment. Inactivation of p53 by shRNA in cell lines expressing wt-p53 abolished the inhibition of cell proliferation and appearance of senescence in response to SCH 1450206, suggesting the cellular activity of SCH 1450206 is p53 specific and mechanism-based. Taken together, our results demonstrated the mechanism of action of SCH 1450206, a novel HDM2 antagonist that can activate the p53 pathway, and offers a potential anti-tumor agent targeting tumors expressing wild-type p53.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4534.
Abstract 4540: Preclinical pharmacology and antitumor activity of CP-744809, a highly selective orally available small molecule inhibitor of aldose reductase
Authors: Griggs David W. , Shannon Kristen E. , Hauser Scott D. , Matulewic David A. , Baratta Michael T. , Pegg Jodi A.
Published: February 2011

Aldose reductase (AKR1B1) mediates the first and rate limiting step in the conversion of glucose to polyols that contribute to redox imbalance, formation of reactive oxygen species, and activation of signal transduction pathways that can promote tumor formation and tumor growth. Aldose reductases are overexpressed in a variety of human tumors, and genetic or pharmacological blockade of AKR1B1 has been reported to attenuate these processes.

CP-744809 is a highly potent and selective aldose reductase enzyme inhibitor which has been previously shown to provide efficacy in an experimental model of diabetic retinopathy. The compound has properties of high oral bioavailability, very high protein binding, and a very long half life in vivo. In this study, we have characterized the activity of this agent in animal models of angiogenesis and tumor growth.

CP-744809 treatment significantly reduced VEGF-induced angiogenesis in a dose-dependent manner in the rat corneal micropocket assay, suggesting a heretofore unrecognized role for aldose reductase in this process. Interestingly, when the related aldose reductase inhibitor Zopolrestat was administered to normal rats, a significantly decreased level of the angiogenic lipid mediator sphingosine-1-phosphate was observed along with other lipid changes. In xenograft models, the CP-744809 treatment was associated with significant and reproducible reduction in tumor size that was dose dependent and superior to treatment with Zopolrestat. Final tumor mass in individual animals was highly correlated with the corresponding intratumoral drug concentration. In contrast, drug concentrations in serum were poorly correlated with drug concentrations in tumor or with tumor mass. Serum drug concentrations at every dose were consistently 7-10 fold higher than those observed in tumor, suggesting a barrier to optimal penetration of tumor tissue by the compound. Pooling data from multiple in vivo studies, the total intra-tumoral drug concentration (protein bound and unbound) required to achieve half maximal efficacy (EC50) was estimated to be 77 micrograms/ml.

These results confirm the therapeutic potential of aldose reductase as an interesting cancer target, and have uncovered a novel antiangiogenic activity. They also highlight the obstacle that adequate tumor tissue penetration may pose for clinical development of agents such as CP-744809. Combination treatments with other agents are being evaluated to assess the potential for synergistic activity with the vascular and inflammation modulating properties of aldose reductase inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4540.
Abstract 4541: The design, synthesis and evaluation of selective FR α and β substrates with potent GARFTase inhibitory activity as antitumor agents
Authors: Zhou Xilin , Zhang Xin , Gang Aleem , Cherian Christina , Hou Zhanjun , Matherly Larry H. , Kisliuk Roy L.
Published: February 2011

Glycinamide ribonucleotide formyl transferase (GARFTase) catalyzes the first of two formyl transfer steps in the de novo purine biosynthetic pathway. Potent inhibitors of GARFTase and de novo purine biosynthesis have shown promise as antitumor drugs. However, a lack of selectivity and toxicity has been a major hurdle for GARFTase inhibitors as cancer chemotherapeutic agents. We recently reported a series of thieno[2,3-d]pyrimidine classical antifolates that are specifically taken up by the folate receptor (FR) and inhibit FR expressing tumor cells at nanomolar IC50 values (IC50= 4.9 nM in human KB tumor cells, IC50= 5.9 nM in human IGROV1 tumor cells,). GARFTase was confirmed as the target. Notably, the thieno[2,3-d]pyrimidine antifolates are unique and distinct from all other classical antifolates evaluated, including pemetrexed (PMX), raltitrexed (RTX), and methotrexate (MTX) in that they are neither substrates for reduced folate carrier (RFC) nor for the proton-coupled folate transporter (PCFT). This characteristic results in selective targeting of FR-expressing cells, without toxicity to normal cells that express RFC. To further investigate the structural requirements of antifolates with respect to FR substrate activity, a series of four 2-amino-4-oxo-6-substituted thieno[2,3-d]pyrimidines with different aryl side chains were synthesized. This afforded potent antitumor agents with increased inhibitory activity against FRα expressing tumor cells (IC50= 2 nM in human KB tumor cells) 2.5- fold more potent than the lead benzoyl compound. In addition, these thieno[2,3-d]pyrimidines were specific for FRα and were not transported by RFC or PCFT and indicated that the nature of the bicyclic scaffold is an important structural determinant for transport specificity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4541.
Abstract 4549: Plasma pharmacokinetics and oral bioavailability of the 3,4,5,6-tetrahydrouridine (THU) prodrug, triacetyl-THU (taTHU), in mice
Authors: Beumer Jan H. , Eiseman Julie L. , Gilbert Judith A. , Holleran Julianne L. , Yellow-Duke Archibong E. , Clausen Dana M. , D'Argenio David Z. , Ames Matthew M. , Hershberger Pamela A. , Parise Robert A. , Bai Lihua , Covey Joseph M. , Egorin Merrill J.
Published: February 2011

Introduction

Cytidine drugs, such as gemcitabine, undergo rapid, inactivating catabolism by cytidine deaminase (CD). 3,4,5,6-tetrahydrouridine (THU), a potent CD inhibitor, has been applied preclinically and clinically as a modulator of cytidine drug metabolism. However, p.o. THU is at most 20% bioavailable (Beumer et al.), which limits its preclinical evaluation and clinical use. Therefore, the more lipophilic prodrug triacetyl THU (taTHU) was developed. We characterized THU pharmacokinetics after administration of taTHU to mice.

Methods

Mice were dosed 150 mg/kg taTHU i.v. or p.o. Plasma and urine THU concentrations were quantitated with a validated LC-MS/MS assay. Plasma and urine pharmacokinetic parameters and p.o. bioavailability were calculated non-compartmentally and compartmentally. We assessed taTHU inhibition of metabolism of gemcitabine by recombinant CD.

ResultsTHU parameterstaTHU i.v. 150 mg/kgtaTHU p.o. 150 mg/kgCmax (µg/mL)10611.8Tmax (min)560Half-life (min)235122AUC0-inf (mg/mL*min)7.553.36Vd/F (L/kg)4.495.26Cl/F (mL/min/kg)13.229.8F-THUi.v. (%)68.030.3% dose in 0-16 h urine405.6% dose in 0-24 h urine5512

THU, after 150 mg/kg taTHU i.v., had a 235 min terminal half-life and produced plasma THU concentrations >1 µg/mL, the concentration shown to inhibit CD, for 10 h. A multi-compartment model fit the data best. 150 mg/kg p.o. taTHU produced a concentration versus time profile with a plateau of approximately 10 µg/mL from 0.5-2 h, followed by a decline with a 122 min half-life. Approximately 68% of i.v. taTHU was converted to THU. Approximately 30% of p.o. taTHU reached the systemic circulation as THU. After i.v dosing, renal excretion accounted for 40-55% of the taTHU dose, 26-35% as THU and an additional 14-19% as acetylated forms of THU. After p.o. dosing, the renal excretion percentages were 6-12%, 5.2-11%, and 0.42-0.71%, respectively. taTHU did not inhibit recombinant CD.

Conclusion

The availability of THU after p.o. taTHU in mice is 30%, as compared to the 20% achieved after p.o. THU. Clinical studies are warranted to evaluate availability of THU from taTHU in humans.

Support: N01-CM07106, N01-CM52202, P30-CA47904 from the NCI and P41-EB001978.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4549.
Abstract 4555: Remote sensing image dtection; a new tool for evaluation the tumor thickness in tongue SCC
Authors: Chang Kuo-Wei Chang , Wong Yong Kie , Wong Mark , Chang Chein-I
Published: February 2011

A preoperative predictor of the risk of subclinical nodal metastasis would be useful. Studies have shown a strong correlation between histological tumor depth and the risk of nodal metastasis. To assess if preoperatively measured tumor depth predicts an increased risk of subclinical metastatic neck disease and thus the need for elective neck dissection. To further pin-point the boundary between normal to infective tissues, biopsy is generally performed. However, the similarity and the general nature of tissue substances between normal and cancer cells are sometimes hard to distinguish by human eyes. This is also true for experienced radiologist. Therefore, computer aided cancer cell classification is highly beneficial for such diagnoses. In this presentation, we implemented methods that are found highly successfully in satellite remote sensing image detection and classification. These methods can be grouped into two major categories, supervised and unsupervised classification. The supervised methods, Least Squares Orthogonal Subspace Projection (LSOSP), Non-negative Constraint Least Squares (NCLS) and Fully Constraint Least Squares (FCLS), require a detail library of every possible tissue signatures consist in the MR image. But, the classification results can be generally more accurate. On the other hand, the unsupervised methods, Automatic Target Detection (ATGP), Unsupervised Non-negative Constraint Least Squares (UNCLS), and Unsupervised Fully Constraint Least Squares (UFCLS), can automatically generate tissue classification results. However, parameters for these techniques such as the number of tissues need to be predefined. Also, the cancer cell classification still needs human intervention to justify the location of infectious region. Based on our experiments, both category of methods are show promising results.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4555.