bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 5659: Down-regulation of hTERT sensitizes chemotherapeutic effects of docetaxel in human prostate cancer cells via suppression of PIM-1 oncogene
Authors: Rajendra Ashoka S. , Jagadeesh Shankar , Banerjee Partha P.
Published: February 2011

Taxanes comprise some of the most widely used cancer chemotherapeutic agents for various cancers. Docetaxel is an effective first-line treatment for hormone-refractory prostate cancer. However, despite the recently demonstrated survival benefits of docetaxel-based chemotherapy, most patients will move from response to progression within 6 months. Moreover, effective concentrations of docetaxel have side effects including localized erythema of the extremities with edema followed by desquamation, severe neuropathy, fatigue, and weakness which can have debilitating effects in patients with prostate cancer. One reason for disease progression is the up-regulation of PIM-1 expression following docetaxel treatment of prostate cancer cells. PIM-1 is a serine-threonine kinase that promotes survival by inhibiting the activity of apoptotic proteins. In a recent study, we observed that a telomerase suppressing small molecule MST-312, and hTERT siRNA down-regulated PIM-1 protein level in prostate cancer cells. These results prompted us to investigate whether combination of docetaxel with inhibition of telomerase by MST-312 or TERT siRNA would have synergistic effects on prostate cancer cell growth and induce death. Treatment of PC3 cells with 1 nM of docetaxel for 3 days substantially promoted the viability of cells compared to the control, with a 27% increase in cell number. This increase was associated with the up-regulation of PIM-1. Treatment of telomerase inhibitory concentration (2 μM) of MST-312 over 3 days resulted in a 51% decrease in cell viability relative to the 1 nM docetaxel treated groups, associated with a decrease in PIM-1 protein levels. More interestingly, treatment of 2 μM MST-312 with 1 nM docetaxel for 3 days resulted in 72% reduction in cell viability compared to docetaxel alone and 43% reduction in cell viability compared to MST-312 alone. This combined treatment also resulted in lower levels of PIM-1 activity than MST-312 or docetaxel treatment alone. These results suggest that there is synergy between the combination of telomerase inhibitor MST-312 with docetaxel in the treatment of metastatic prostate cancer. This can be explained by the down-regulation of PIM-1 kinase that promotes resistance to docetaxel treatment. These findings suggest potential clinical benefit by the combined use of docetaxel and telomerase inhibitors for prostate cancer treatment.

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 5659.
Abstract 5660: Galbanic acid downregulates androgen receptor and induces G1 arrest and apoptosis in LNCaP cells
Authors: Zhang Yong , Kim Kwan-Hyun , Lee Hyo-Jeong , Kim Sung-Hoon , Lü Junxuan
Published: February 2011

Studies have demonstrated that androgen receptor (AR) is crucial for the genesis and progression of human prostate cancer (PCa). Targeting AR signaling is an important approach for the prevention of PCa. Identification of novel herbal phytochemicals that target AR signaling from Oriental medicinal herbs holds the promise to deal with this malignant disease at the root. Ferula asafetida is used as a food spice and as a traditional herbal medicine for many illnesses in Asia, where the incidence of PCa is lower than that in USA. We report here, for the first time, that one of the main components of ferula asafetida, galbanic acid (GA) down-regulates AR and suppresses the growth of LNCaP cells via an induction of G1 arrest and apoptosis. After exposure to GA for 24h and 48h, GA dose-dependently decreased cellular AR level via posttranscriptional and posttranslational regulation in LNCaP cells. Consequently, GA dose-dependently reduced PSA protein expression and inhibited its AR-dependent promoter transactivation. Flow cytometric analysis showed that GA does-dependently induced G1 arrest accompanied by a decrease of CDK4, dephosphorylation of RB and inhibition of E2F1-dependent target gene products, but independent of p21 and p27. In addition, GA induced moderate apoptosis characterized by increased cleaved PARP, DNA fragmentation and annexinV staining as early as 6h after treatment. The induction of apoptosis was attenuated by a general caspase inhibitor (zVADfmk), supporting caspase-dependency. Furthermore, colony formation assay showed that GA suppressed the growth of LNCaP cells with an IC50 of approximate 7 microM. In contrast, GA did not affect the cell cycle distribution or apoptosis or growth of AR-independent DU 145 or PC-3 cells at the same doses of exposure. Taken together, these data suggests that GA exerts growth inhibitory effect against AR-dependent PCa with down-regulation of AR signaling and the induction of G1 arrest and apoptosis.

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 5660.
Abstract 5668: Nexrutine, a phellodendron amurense extract protects against breast cancer
Authors: Lanza-Jacoby Susan , Yan Guang , Wang Chenguang
Published: February 2011

Breast cancer is the most common cancer in women with over 40,000 deaths per year in the United States. Prognosis is poor for a subset of women with estrogen receptor (ER) negative or ErB2 overexpressing ER negative tumors because their cancers are aggressive and do not respond to conventional treatment. This emphasizes the importance of developing new agents and protocols for preventing breast cancer. Numerous epidemiological studies suggest that plant-based diets are protective against many types of cancer. Nexrutine, an herbal extract from the Chinese plant Phellodendron amurense, has been used for centuries in Chinese medicine to treat inflammation, gastroenteritis, abdominal pain, and diarrhea. The anti-inflammatory properity of Nexrutine is of particular relevance considering the relationship of inflammation to cancer. Many tumors including those of the breast have high levels of cyclooxygenase (COX)-2., which result in increased levels of the proinflammatory mediator prostaglandin (PG) E2.

In this study we investigated the anti-cancer effects of Nexrutine on several breast cancer cell lines. Nexrutine decreased activities of COX-2 and peroxisome proliferators activated receptor gamma (PPAR)γ; two potential biomarkers of breast cancer. Nexrutine reduced the production of PGE2, which was associated with decreased protein expression of microsomal PGE2 synthase (mPGES) and increased PG 15-dehydrogenase (15-PGDH). The Nexrutine decreased cell survival, which was accompanied by a G1 cell cycle arrest, increased autophagy, and cell death in SkBr3 and MDA-MB 231 cells. Analysis of the cell cycle regulators indicated a decrease in Cyclin D1, cdk 2, Cyclin E, and decreased phosphorylation of retinoblastoma protein and increase in p21 and p27. Based upon these findings, we propose that the use of Nexrutine could provide a novel approach for protection against breast 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 5668.
Abstract 5669: Aldose reductase is a novel therapeutic target to prevent oxidative stress-induced inflammatory signals in prostate cancer
Authors: Tammali Ravinder , Ramana Kota V. , Srivastava Satish K.
Published: February 2011

Prostate Cancer (PC) is one of the most common cancers in American men, especially as they age. Although PC initially responds to androgen therapy, as the cancer progresses it usually becomes androgen-independent and prone to metastasis and multi-drug resistance, which kills the majority of patients within 5 years of diagnosis. Therefore, it is necessary to develop better therapeutic strategies which could prevent both early and late stage PC. Our recent studies demonstrate that Aldose Reductase (AR) is the main mediator of inflammatory signals induced by growth factors, cytokines, chemokines, carcinogens etc. Since inflammation is known to play a central role in PC, we investigated the possible role of AR in heterogenous androgen-dependent, -independent, and multi-drug resistant PC cells. Using androgen -dependent LNCaP and -independent PC-3 cells, we have determined the effect of AR inhibition on growth factors such as IGF- and EGF -induced proliferation, cell cycle progression, and generation of reactive oxygen species (ROS). We also determined the effect of AR inhibition on the phosphorylation/expression of androgen receptor, PSA, AKT/PI3K, NF-kB etc in PC cells. Our results show that inhibition of AR by fidarestat significantly prevented the IGF -and EGF-induced proliferation and generation of ROS in both androgen -dependent (LNCaP) and -independent (PC3) PC cells. Cell cycle analysis suggested that inhibition of AR prevents IGF-induced entry of cells from G1 to S phase in PC3 cells. Inhibition of AR also prevented IGF-induced activation of AKT/PI3K and NF-kB. Results with androgen-dependent LNCaP cells showed that inhibition of AR prevented the phosphorylation of androgen receptor, and secretion and expression of PSA when cells were cultured in 5% serum. Further, inhibition of AR increased the drug-sensitivity of multi-drug-resistant PC3 cells against chemotherapeutic agents such as cisplatin, docetaxel, doxorubicin, and methotrexate. These results indicate that AR mediates oxidative stress -induced inflammatory signals in prostate carcinogenesis. Hence, AR inhibition could be a potential therapeutic target against prostate 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 5669.
Abstract 5670: Piceatannol, a catechol-type polyphenol, inhibits phorbol ester-induced NF-κB activation and cyclooxygenase-2 expression in human breast epithelial cells: Cys179 of IKKβ as a potential target
Authors: Son Phil-Soon , Park Sin-Aye , Na Hye-Kyung , Surh Young-Joon
Published: February 2011

There are multiple lines of evidence supporting that inflammation is linked to carcinogenesis. Nuclear factor-κB (NF-κB), a master redox-sensitive transcription factor responsible for the induction of a wide array of proinflammatory genes, is frequently overactivated in many tumors. Moreover, constitutive activation of IκB kinase (IKK), a key regulator of NF-κB, has been implicated in inflammation-associated tumorigenesis. Piceatannol (3,5,3′4′-tetrahydroxy-trans-stilbene: PIC) derived from grapes, Rhubarb, and sugar cane, exhibits immunosuppressive and antitumorigenic activities in several cell lines, but the underlying mechanisms are poorly understood. In the present study, we found that PIC inhibited migration and anchorage-independent growth of human mammary epithelial cells (MCF-10A) treated with the prototypic tumor promoter, 12-O-tetracecanoylphorbol-13-aceate (TPA). PIC treatment suppressed the TPA-induced activation of NF-κB and cyclooxygenase-2 (COX-2) expression in MCF-10A cells. We hypothesize that an electrophilic quinone formed as a consequence of oxidation of PIC bearing the catechol moiety may directly interact with critical cysteine thiols of IKKβ, thereby inhibiting its catalytic activity. The reducing agent dithiothreitol and the antioxidant N-acetylcysteine abrogated inhibitory effects of PIC on TPA-induced activation of NF-κB and expression of COX-2. PIC incubated with whole cell lysate from MCF-10A cells stimulated with TPA inhibited IKKβ kinase activity. The inhibitory effect of PIC was reversed when DTT was cotreated. In addition, the inhibitory effects of PIC on NF-κB signaling and COX-2 induction were blunted in cells expressing mutant IKKβ (C179A) in which cysteine 179 was replaced by alanine. In conclusion, our results suggest that modification of cysteine residues of IKKβ by PIC blocks NF-κB activation signaling and COX-2 induction in TPA-treated MCF-10A cells and also migration and transformation of these 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 5670.
Abstract 5677: Inhibition of Azoxymethane-induced aberrant crypt foci in C57BL/6 mice by the Chinese medicinal herb Scutellaria barbata
Authors: Wong Brian Yuen Yau , Kim Lucas Y. , Kim Brian Y. , Jung Jeeyoon , Nishikawa Christal Y. , Zima Alyssa K. , Hausted Randy P.
Published: February 2011

Scutellaria barbata (SB) is a perennial herb of the mint family which has been used to treat appendicitis, hepatitis, pulmonary abscess, and cancers of the liver, lung, and colon in Chinese medicine. Our early studies showed that SB contained phytochemicals that inhibited mutagenesis, DNA binding, and metabolism of aflatoxin B1 (AFB1) and benzo[a]pyrene bioactivated by Arcoclor 1254-induced rat S9. It also inhibited the mutagenicity of AFB1 bioactivated by either non-induced or DXM-induced hepatic S9, suggesting its effect via an inhibition of CYP3-mediated metabolism of [3H]AFB1. Recent oral feeding data demonstrated that SB could delay prostate tumor development in TRAMP mice. Complementary in vitro data indicated that SB may exert this function via up-regulating the apoptotic pathway and down-regulating the survival pathway in murine (TRAMP-C1) and human (LNCaP) prostate cancer cells. Inhibitory effects of SB were also observed in inducing cell death in human (LoVo) colon cancer cells. This study investigated the effects of SB on azoxymethane (AOM)-induced aberrant crypt foci (AFC) formation in C57BL/6 mice. Thirty C57BL/6 mice of 9 wks old were randomized into three groups (N=10). Mice of the positive control and experimental groups were injected with AOM (5 mg/kg body wt) at the beginning and second wk of the 8-wk duration while the negative control group received no injection. Animals in the experimental group received daily oral feedings of 24 mg SB since day 1 while mice in the other two groups were given sterilized-water placebo. SB feeding significantly reduced the number of AOM-induced ACF in the proximal colon (25 mm) compared with the water-fed positive control AOM-induced group (8.35 ± 5.56 < 32.1 ± 9.86; P< 0.000047). The negative non-induced group had minimal ACF (2.0 ± 1.56) compared to the experimental and positive control groups (P< 0.0056; P< 0.0000034 respectively). The potency index of the herb was calculated as 3.84. Significant percent inhibition (74%) of AOM-induced ACF formation was obtained with SB treatment. Mice in all three groups had gained wt (% increase) in the course of the experiment (negative control, 16.2 ± 4.32 < experimental, 20.7 ± 10.39 < positive control, 35.78 ± 16.79). These in vivo data suggest the potential chemopreventive and treatment potential of SB.

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 5677.
Abstract 5679: Differential phosphorylation of EGFR in response to PUFA supplementation
Authors: Hernandez Karla , Rogers Kristina R. , Kikawa Keith D. , Mouradian Michael , Pardini Ronald S.
Published: February 2011

Epidermal Growth Factor Receptor (EGFR) is a 170 kDa transmembrane glycoprotein responsible for the initiation of a variety of cellular signaling cascades governing cell proliferation and survival, which are initiated by specific phosphorylation sites in its tyrosine-kinase domain (TKD). Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid (PUFA) that has been demonstrated to have positive effects on human health, including the inhibition of tumor growth in various cancer cell lines, both in vivo and in vitro. Preliminary data in our laboratory has shown that supplementation with both DHA, and the omega-6 PUFA, linoleic acid (LA), are capable of upregulating total EGFR phosphorylation in the TKD. Subsequent investigations have identified that increased EGFR phosphorylation in DHA treatments is largely due to enhanced phosphorylation at one particular site, the tyrosine 1068 residue. However, because EGFR has numerous activation sites, a systematic evaluation of the changes in EGFR phosphorylation upon supplementation with DHA and LA is necessary. The current research demonstrates specific EGFR phosphorylation events that are altered by PUFA supplementation. This data will provide critical insight into how PUFAs may be exerting some of the many other signaling changes that have been associated with their use (i.e. decreased p38, MAPK, pAkt, etc.).

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 5679.
Abstract 5681: Flavokawain B down-regulates SKP2 through a proteasome-dependent and ubiquitin-independent pathway, and acts synergistically with Bortezomib on inhibition of Skp2 expression and prostate cancer cell growth
Authors: Li Xuesen , Liu Zhongbo , Simoneau Anne R. , Zi Xiaolin
Published: February 2011

The E3 ubiquitin ligase SKP2 (S-phase kinase-associated protein 2), an oncogenic protein, was found to be overexpressed in 557 of 622 (89.2%) primary prostate cancer (PCa) samples and in 64 of 74 samples (86.4%) high-grade prostatic intra-epithelial neoplasia lesions. In addition, a transgenic mouse model with prostatic over-expression of SKP2 develops low-grade adenocarcinomas. These results suggest that SKP2 could be a potential target for PCa chemoprevention. In a search for SKP2 targeting agents for PCa chemoprevention, we found that Flavokawain B, a chalcone found in multiple edible plants- including roots of Alpinia speciosa (family Zingiberaceae) and Piper methysticum Forst (kava kava), potently down-regulates the protein expression of SKP2 in several prostate cancer cell lines (LNCaP, C4-2B, DU145 and PC3) at a concentration of 8.8 µM. More importantly, Flavokawain B reduces the cell viability of transfected PC3 cell line stably overexpressing SKP2 compared to vector control-transfected PC3 cells (IC50s are 7 and 26.4 µM, respectively), which suggest that flavokawain B may target SKP2 for its growth inhibitory effect. Flavokawain B treatment did not decrease the promoter activity and mRNA levels of SKP2. Instead, Flavokawain B decreases the protein levels of both a native and a myc-tagged SKP2 in PC3 cells through promoting its degradation. The degradation of the myc tagged SKP2 can be recovered by a proteasome inhibitor MG132. MG132 treatment resulted in an increase of ubquitinated SKP2, whereas Flavokawain B did not affect SKP2 ubquitination. These data suggest that the degradation of SKP2 by Flavokawain B may be through a proteasome-dependent and ubquitination-independent pathway. Interestingly, proteasome inhibitors (MG132 and Bortezomib) also down-regulate SKP2 mRNA expression through transcriptional inhibition, and combination of Bortezomib or MG132 with Flavokawain B exhibits a synergistic effect on SKP2 down-regulation and cell growth inhibition via induction of G2M arrest in PCa cell lines. Taken together, Flavokawain B is a novel SKP2 target agent and deserves further investigation for PCa chemoprevention and therapy.

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 5681.
Abstract 5686: Linoleic acid supplementation upregulates phosphatidylinositol-3-kinase signaling by increasing the association between Gab1 and EGFR
Authors: Kikawa Keith D. , Johnson Eric D. , McKinnon Kristen M. , Rogers Kristina R. , Pardini Ronald S.
Published: February 2011

The omega-6 polyunsaturated fatty acid, linoleic acid (LA), is prevalent in Western diets and is known to enhance the tumorigenesis of mammary cancer models; with previous work demonstrating an upregulation of phosphatidylinositol-3-kinase (PI3K) signaling may play a key role. The Grb2-associated binding protein 1 (Gab1) is a scaffolding protein that can complex with the epidermal growth factor receptor (EGFR) to activate PI3K signaling. Recent studies in our laboratory reveal LA supplementation of the breast cancer cell lines MDA-MB-231 and BT-474 greatly increases the association between Gab1 and EGFR, while at the same time dramatically decreasing Gab1 protein levels. These changes are concomitant with increases in activated Akt (pAkt), a downstream signaling component in the PI3K signaling pathway. Moreover, inhibitors of EGFR and Gab1-specific siRNAs are capable of reversing LA-induced upregulation of pAkt, as well as observed increases in cell proliferation for these models. Finally, we were able to confirm these findings in the A549 lung cancer cell line, validating the potential relevance to tissues other than breast cancer cell lines. These data establish Gab1 as major target in LA-induced enhancement of tumorigenesis.

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 5686.
Abstract 5689: Phtalates toxicity on normal lymphocytes
Authors: Rosado Carlos A. , Velez Christian , Zayas Beatriz
Published: February 2011

The main purpose of this study is to determine the toxicity and cell death mechanism of the phthalate Di-ethylhexyl (DEHP) and its principal metabolite, Mono-ethylhexyl (MEHP) on the TK-6 human lymphocytic cell line. Phthalates are a family of compounds used widely in the manufacturing industry and in the production of plastics. Exposure to these compounds can be through plastic items and personal care products. Phthalates are considered estrogen disrupters and effects on the reproductive and respiratory systems have also been reported by the scientific community. Studies, of the effect of phthalates on the immune system however are limited. The analysis of the effects of phthalates on normal lymphocytes could allow the development biomarkers of exposure to phthalates. TK-6 lymphocytes cells were cultured on 25cm2 flasks on modified RPMI culture media with 10% FBS, and incubated at 37oC and 5% CO2. TK-6 cells were exposed to DEHP or MEHP at doses ranging from 5μM, to 350μM for 48 and 72 hours. Cytotoxicity, ROS generation and mitochondrial membrane permeabilization were measured by Trypan Blue exclusion, DCFH-DA ROS assay and Mito PT assay respectively. Cytotoxicity results indicated higher resistance of TK-6 to the parent compound DEHP in comparison to the metabolite MEHP with IC50s of 100uM and 75uM respectively. Preliminary ROS generation analyses suggest induction of ROS generation by both parent and metabolite. mitochondrial membrane permeability analysis also indicated some degree of mitochondrial interaction.

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 5689.
Abstract 5691: Significance of combination treatment of antiprogestin and aromatase inhibitors in aromatase overexpressing T47D breast cancer cells
Authors: Gupta Akash , Peng Xinjian , Murillo Genoveva , Mehta Rajeshwari R. , Wiehle Ronald , Mehta Rajendra G.
Published: February 2011

Treatment with aromatase inhibitors (AI) is considered as the first line of treatment for ER+PR+ cancers. However, many patients acquire resistance to aromatase inhibitors. Therefore, there is a need for new approaches to overcome resistance to AI in these patients. In the present study we determined the effects of third generation AI in genetically engineered high aromatase overexpressing T47Darom cells. Treatment of T47Darom cells with Leterozole (L), Anastrazole(A) and Exemestane(E) at 5μM concentration exhibited inhibition of 32% 19% and 18% respectively, however, in combination with proellex overall inhibition increased to 50% suggesting additive effect of proellex along with aromatase inhibitor. Interestingly, Proellex showed dose-dependent inhibition of T47Darom cells incubated with testosterone (1nM and 10nM) suggesting that Proellex also has aromatase inhibitory property. Furthermore, Proellex inhibited cell proliferation of both ER/PR positive (T47D and T47Darom) and ER/PR negative (MDA-MB231cells). These results suggested that the mechanism of action may not be entirely dependent to PR status. Since both T47Darom and MDA-MB231 cells exhibit increased COX2 expression and increased COX2 expression has been associated with enhanced cell proliferation and malignancy in breast cancer, we determined the effects of Proellex on COX2 expression. Results showed that in both these cell lines COX2 expression was decreased as determined by real-time PCR when the cells were treated with Proellex at 10−6M. These studies suggest that Proellex either alone or in combination with aromatase inhibitors may provide a new treatment strategy for breast cancer patients.(This work is supported by Repros Therapeutics)

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 5691.
Abstract 5693: Changes in antioxidant capacities of isolated radish components during growth
Authors: Whitaker Jonathan , Giraldez Evita , Loong Jason , Wagstaff Joel , Robinson Richard , O'Neill Kim L.
Published: February 2011

Radishes have been cultivated and used in the diet since the Hellenistic age and have become a common vegetable in grocery stores in North America. Radishes belong to the genus Brassica and recent research has indicated the consumption of this plant has protective properties against colorectal cancer.

This project examines the antioxidant (AO) properties of the leaves, stems, body, and the roots of cherry belle radishes at different stages of growth from germination to maturity. For this experiment, AO capacity was measured using the oxygen radical absorbance capacity (ORAC) assay. The ORAC assay involves mixing samples from the radish components with fluorescein, a fluorescence agent, and measuring the degradation of fluorescein after AAPH ((2,2′)-azobis-(2-amidinopropane) dihydrochloride), an oxidizer, is added. Using a trolox (6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) standard, the results from the ORAC assay were converted to trolox equivalents per liter (TE/L). Results indicate that shortly after germination, about 14 days after planting, the body of the radish plants have the highest mean AO capacity with a TE/L reading of 32, compared to the leaves’ initial reading at 26 TE/L. As the plant nears maturity, 23 days after planting, the leaves become the best source of AO at 78 TE/L, and the body's mean AO capacity reaches 73 TE/L. The stems begin as a relatively weak source of AO at 22 TE/L, but mature to 71 TE/L. The roots of the radish plant were consistently the lowest source of AO at 16 TE/L at day 14, and 61 TE/L at day 23.

In addition, a cellular model was used to determine how well the AO are taken into cells that have been distressed. This assay measures the uptake of AO in cells over 10, 20, 45, and 60 minutes after the cells have been exposed to a known oxidant, AAPH. Raji cells, a Burkitt's lymphoma cell line, were treated with samples derived from the same parts of the radish plant after they were pretreated with AAPH. Preliminary data indicate cells continually uptake AO derived from the radish leaves up to and possibly beyond 60 minutes. Pre-stressed cells exposed to AO from stems lose AO capacity over the 60 minutes. In the cells exposed to root samples AO uptake does not change significantly over time. In summary, radish leaves at maturity are the best source of antioxidants.

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 5693.
Abstract 5695: Nitric oxide-donating naproxen inhibits β-catenin-mediated TCF signaling in colorectal cancer cells more effectively than naproxen
Authors: Suh EunRan , Ferrara Christina , Kaunga Esther , Cooper Harry S. , Lubet Ronald A. , Chang Wen-Chi L. , Clapper Margie L.
Published: February 2011

Results from recent clinical and epidemiological studies continue to suggest that non-steroidal anti-inflammatory drugs (NSAIDs) are promising chemopreventive agents with activity against colorectal cancer. Nitric oxide (NO)-donating NSAIDs represent a novel class of agents that have been reported to have greater safety and higher efficacy in inhibiting the growth of cancer cells than the parent compounds. However, the mechanism of chemopreventive action of NO-NSAIDs is not well elucidated. Dysregulation of the WNT/ β-catenin pathway is one of the earliest events during tumorigenesis in the colon and thus an attractive molecular target for chemopreventive intervention. The major goal of the current study was to compare the effect of naproxen, an NSAID commonly used to reduce pain, fever and inflammation, and NO-naproxen on β-catenin-mediated TCF4 signaling in colon cancer cells. Human SW480 colon carcinoma cells that express mutant APC were transfected with either pGL3 basic plasmid or a luciferase reporter construct under the control of 3 copies of either wild-type (pGL3-OT) or mutated (pGL3-OF) TCF4 regulatory element using LipofectAmine 2000. Cells were treated with 0.01 - 0.4 mM naproxen or NO-naproxen or vehicle (water or DMSO, respectively) and harvested 48 hrs later. Cell lysates were prepared and luciferase activity was measured using the Promega Luciferase Assay kit. The results demonstrate that NO-naproxen reduces β-catenin-mediated TCF4 transcriptional activity in SW480 cells in a dose dependent manner. At a given dose, the luciferase activity of cells exposed to NO-naproxen was approximately 50% of that of cells treated with the parent compound. In conclusion, these data suggest that the chemopreventive activity of NO-naproxen is attributed in part to its ability to inhibit the transcriptional activation of TCF4; a response that is greater than that of the conventional drug naproxen. The availability of a multiple intestinal neoplasia mouse model that, unlike the conventional strain, develops multiple colorectal adenomas provides a unique opportunity to compare the efficacy of these agents against colorectal tumor growth in vivo. Supported by NIH N01 CN43309.

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 5695.
Abstract 57: Inhibition of human melanoma proliferation by combination treatment with ODC inhibitor and mTOR inhibitor
Authors: Hsueh Eddy C. , Zhang Yanping , Peng Guangyong
Published: February 2011

Recent reports have demonstrated that polyamine synthesis is critical for tumor cell growth. Furthermore, mTOR was also shown to be critical for tumor cell growth. We hypothesized that inhibition of key polyamine synthesis enzyme, ornithine decarboxylase (ODC), and mTOR would have growth inhibitory effect on human melanoma cells.

ODC expression was evaluated in human melanoma and human melanoma cell lines by Western blot using polyclonal goat anti-ODC and quantitative real-time PCR using TaqMan Gene Expression Assay Applied Biosystems). The siRNA duplexes targeting ODC and a scrambled control siRNA were designed and synthesized (Santa Cruz, CA) and transient transfections were performed. Cell proliferation assay was performed using Cell Titer Blue cell proliferation assay according to the manufacturer's protocol. The cells were treated with or without various concentrations of DFMO or rapamycin or combination then incubated up to 96 hours. For comparison between groups, the Student's t test were used and p<0.05 was considered to be statistically significant.

Over-expression of ODC was observed in human melanoma cells compared with tumor asssociated fibroblasts as well as human melanoma cells. Over-expression of ODC was observed in six of the ten human melanoma cell lines on Western blot analysis and RT-PCR analysis. Dose-dependent growth inhibition of human melanoma cells were observed following DFMO treatment (p<0.05) in melanoma cell lines with over expression of ODC and correlated with suppression of ODC expression levels. Grow inhibition was also observed folllowing Rapamycin treatment in the melanoma cell lines. Treatment with ODC-siRNA also resulted in significant growth inhibition of melanoma cell lines. Effects of DFMO induced growth inhibition of melanoma cells were further enhanced with combined treatment with rapamycin.

Overexpression of ODC was observed in human melanoma cells. Inhibition of polyamine synthesis and mTOR can have significant growth inhibitory effects on human melanoma.

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 57.
Abstract 570: Role of NAD(P)H:quinone oxidoreductase 1 (NQO1) in the cytotoxicity of the Hsp90 inhibitor 17AAG in human pancreatic cancer cells
Authors: Shieh Biehuoy , Siegel David , Yan Chao , Kepa Jadwiga K. , Ross David
Published: February 2011

Previous work has demonstrated that NQO1 can reduce the benzoquinone ansamycin Hsp90 inhibitor 17-allyamino-demethoxy geldanamycin (17AAG) to the corresponding hydroquinone (17AAGH2). The formation of 17AAGH2 by NQO1 results in a more water soluble molecule and that binds with greater affinity to Hsp90 when compared to the parent quinone 17AAG. Experiments were conducted with the human pancreatic cancer cell line Panc1 which is homozygous for the NQO1*2 polymorphism and contains only trace levels of NQO1 protein and no NQO1 catalytic activity. An isogenic cell line expressing high levels of NQO1 (Panc1-C5) was generated by stable transfection of wild type NQO1 in Panc1 cells. 17AAG was more cytotoxic to Panc1-C5 cells with high levels of NQO1 when compared to NQO1-null parental Panc1 cells. Pretreatment of Panc1-C5 cells with the NQO1 mechanism-based inhibitor ES936 reduced the cytotoxicity of 17AAG to the level observed in Panc1 cells. No difference in the cytotoxicity of the non-quinone Hsp90 inhibitor radicicol was observed between the two cell lines Biomarkers of Hsp90 inhibition were measured in both Panc1 and Panc1-C5 cells following treatment with 17AAG. Higher protein levels of Hsp70 and lower amounts of cRaf, phosphorylated ERK1/2 and phosphylated MEK were observed in Panc1-C5 cells compared to Panc1 cells. In addition, cell cycle analysis revealed a greater number of Panc1-C5 cells arrested in G2M following 17AAG treatment compared to Panc1 cells. Cytotoxicity studies were also performed in additional human pancreatic cancer cell lines (BxPC3 and MiaPaCa2) that contain high levels of catalytically active NQO1*1 protein and in agreement with the studies described above the cytotoxicity of 17AAG could be reduced significantly following pretreatment with the NQO1 inhibitor ES936. The intracellular concentrations of 17AAG and 17AAH2 were measured in human pancreatic cancer cell lines and it was observed that greater amounts of both 17AAG and 17AAGH2 could be detected in cell lines with catalytically active NQO1 when compared to cells lacking NQO1 activity or cells pretreated with ES936. These data demonstrate that in addition to generating a more potent Hsp90 inhibitor (17AAGH2) the reduction of 17AAG to 17AAGH2 by NQO1 leads to significantly greater intracellular concentrations of 17AAG and 17AAGH2. These data confirm the role of NQO1 in sensitivity to 17AAG and suggest that genotyping for the NQO1*2 polymorphism should be considered in patients undergoing 17AAG treatment for pancreatic cancer or other solid tumors that are known to contain high levels of NQO1 activity (Supported by CA51210).

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 570.
Abstract 5705: Inhibition of hedgehog-signaling by extracts of the Sutherlandia and elderberry
Authors: Lu Yuan , Lin Hui , Drenkhahn Sara K. , Starkey Nicholas J.E , Jackson Glenn A. , Thomas Andrew L. , Folk William , Fritsche Kevin L. , Lubahn Dennis B.
Published: February 2011

Many botanical compounds, which have been proposed to prevent cancer, may potentially work via inhibition of the hedgehog-signaling pathway. Here we investigated the potential of Sutherlandia and elderberry to prevent and/or treat prostate cancer by inhibition of the hedgehog-signaling pathway. To determine hedgehog pathway inhibitory activity, we treated Shh light II cells with multiple doses of Sutherlandia extract or elderberry extract, in a Gli1 reporter assay to determine the extracts'effects on Gli1 concentration. The Sutherlandia extract was prepared by methanol extraction of Sutherlandia frutescens, while the elderberry extract was prepared by ethanol extraction of Sambucus nigra berries. We hypothesized that the compounds canavanine, from Sutherlandia, and cyanidin-3-glucoside, from elderberry, were the active compounds able to inhibit hedgehog signaling.

Results: We found that a 1:2000 dilution of Sutherlandia extract and a 1:100 dilution of elderberry extract are able to inhibit hedgehog pathway activity by 99% and 94%, respectively, as monitored by Gli reporter assay. Moreover, cyanidin-3- glucoside (5uM, 10uM and 50uM) can inhibit hedgehog activity by 44%,62% and 81% respectively, and canavanine (1uM and 10uM) can inhibit hedgehog activity by 5% and 15% respectively. These data indicate that, while these two compounds are weak hedgehog inhibitor compounds, they are unlikely to be the major active hedgehog inhibitory compounds in Sutherlandia and elderberry.

Conclusion: Our results suggest that these two plants offer a potentially cheap and effective alternative to cyclopamine for cancer therapies. Additionally, these plants may yield novel targets that potentially could lead to a second generation hedgehog inhibitor, if resistance is found to the first generation drugs currently in clinical trials.

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 5705.
Abstract 5706: High-throughout library screening identifies phytochemical inducers of phase II metabolism enzymes GSTP1 and NQO1 in human lung cells
Authors: Tan Xiang-Lin , Shi Miao , Massimi Aldo , Han Weiguo , Spivack Simon
Published: February 2011

Many phytochemicals possess anti-oxidant and cancer-preventive properties, some putatively through phase II metabolism-mediated mutagen/oxidant quenching. However, in studies to date, most candidate agents are not active in human lung cells. In vitro and in vivo screening studies for discovery are clearly needed for new, more potent chemopreventive agents for lung cancer. Here we applied an mRNA-specific gene expression-based high-throughout screening approach to identify phytochemical inducers of phase II metabolism enzymes GSTP1 and NQO1 in primary normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cells (HBEC). We have screened 800 compounds in the MicroSource Natural Products Library for inducers of GSTP1 and NQO1 expression, and identified 2, 3-dihydroxy-4-methoxy-4′-ethoxybenzophenone, triacetylresveratrol, ivermectin, sanguinarine sulfate, and daunorubicin as new inducers for GSTP1 and NQO1 mRNA expression. Consistent with this effect, the induction of NQO1 protein expression by immunoblot was found for all these agents in both HBEC and NHBE cells at the same concentration that induced NQO1 mRNA expression. However, GSTP1 protein expression did not significantly change with any selected agents. Proliferation/viability assays showed that HBEC and NHBE were significantly inhibited by ivermectin, sanguinarine sulfate, and daunorubicin. These data demonstrate the feasibility of high-throughput screening for inducers of NQO1. Moreover, the data identify 2, 3-dihydroxy-4-methoxy-4′-ethoxybenzophenone and triacetylresveratrol as the most potent and low toxicity inducers [≥3-6-fold, at the protein level], implying they are potential new agents for further in vitro and preclinical in vivo testing for prevention of oxidant-related disease.

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 5706.
Abstract 571: PK and antitumor activity of DEBIO 0507, a new platinum derivative, in preclinical tumor models
Authors: Mignard Caroline , Bari Virginie , Bichat Francis , Cicurel Lucienne , Vuagniaux Grégoire , Barbier Maryse
Published: February 2011

Background:

Since the introduction of cisplatin, carboplatin and oxaliplatin, several new generations of platinum analogues have been developed as candidates for chemotherapy. DEBIO 0507/NC-4016 is a DACH-Platin Polymeric Micelle. The main objectives of this project were to assess pharmacokinetic (PK) profile of DEBIO 0507 and evaluate its efficacy in preclinical studies against a broad spectrum of experimental tumors including syngenic, xenogenic tumor models and a cisplatin-resistant cell line.

Methods:

PK and biodistribution studies were conducted in multiple matrices (blood, tumor, liver, spleen, kidneys and pancreas) collected in mice bearing C38 mouse colon carcinoma and treated with a single IV injection of DEBIO 0507 at 2 mg Pt/kg.

Antitumor activity of DEBIO 0507 intravenously injected every 4, 7 or 14 days at different doses was investigated in C38 mouse colon carcinoma bearing C57BL/6 mice. Antitumor effect of DEBIO 0507 was also assessed in a panel of human tumor xenografted in nude mice, Calu-6 and A-549 human lung carcinoma, HT-29 human colon carcinoma, PC-3 human prostatic tumor, FaDu human pharynx carcinoma, NIH:OVCAR3 human ovarian tumor, BxPC-3 human pancreas tumor and HepG2 human hepatocarcinoma.

Results:

A concentration of 61 µg Pt/ml was detected in plasma from 5 minutes after injection and persisted during two hours. Platinum was very slowly cleared from plasma as it was still detected 14 days after injection (t1/2α : 40h). An accumulation was observed in tumor from 5 minutes to 8 days after injection and terminal elimination phase was very long since platinum was also detected 14 days after injection. The same PK and BD profiles were observed for other tissues.

DEBIO 0507 was not active in the models of NIH: OVCAR3 human ovarian tumor, BxPC-3 human pancreas tumor and HepG2 human hepatocarcinoma. DEBIO 0507 exhibited a significant and dose-dependent antitumor activity against C38 mouse colon carcinoma when administered every 4, 7 or 14 days (optimal T/C of 0, 0 and 5%, respectively). We also demonstrated growth inhibitory effects of DEBIO 0507 in human PC-3 prostate, Calu-6 lung, FaDu head and neck and A-549 lung tumors xenografted in nude mice when injected with similar doses and schedules (optimal T/C of : 26, 29, 39 and 40%, for each model respectively).

Conclusion:

DEBIO 0507 displayed a marked antitumor activity against a large spectrum of tumor models associated with a long exposure of tumor to Pt. These preclinical results provide useful data to support the design of clinical trials for DEBIO 0507.

DEBIO 0507/NC-4016 was produced by Nanocarrier Co.,Ltd.

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 571.
Abstract 5712: Identification and characterization of high affinity thioaptamer ligands against E-selectin
Authors: Mann Aman , Somasunderam Anoma , Nieves Rene , Gorenstein David , Ferrari Mauro , Tanaka Takemi
Published: February 2011

E-selectin (CD62E, ELAM-1 or LECAM-2) is a calcium dependent cell surface glycoprotein that mediates an adhesion of leukocytes on inflamed endothelium through recognition of specific carbohydrate ligands, sialyl Lewis X (sLeX) and sialyl Lewis A (sLeA). E-selectin expression is transcriptionally induced by NF-κB and AP-1 in response to inflammatory cytokines such as IL-1 and TNF-alpha. Accordingly, elevated E-selectin expression was reported in many types of acute and chronic inflammatory diseases including cancer. Aberrant homing of leukocytes to tumor results in tumor progression and local invasion. In addition, E-selectin and its counter ligands have also been reported to trigger the initial adhesive step of circulating cancer cells to endothelial cells. Therefore, blockade of E-selectin is a promising therapeutic strategy to control pathological infiltration of leukocytes and/or metastatic cancer cells. Thioaptamers (TA) are single stranded DNA molecules with thio substitution in the phosphate backbone, which provide stability against nucleases. Thioaptamer can fold into tertiary structures and bind with high affinity and specificity to a target molecule, and thus suitable for in vivo applications. In this study, we aimed to identify thioaptamer ligands that bind to E-selectin with high affinity and specificity. To achieve this goal, we used two-step selection strategies, recombinant protein based thioaptamer selection from a combinatorial thioaptamer library that contains 10E14 random sequences, followed by a cell based binding to tetracycline inducible E-selectin endothelial cells.

We selected 14 different groups of thioaptamer candidates following 10 iterative cycles of binding to recombinant E-selectin protein. Using Tet-on inducible E-selectin endothelial cells, we identified the lead three TA candidates that bind to E-selectin on the surface of endothelial cells at high affinity (nM range) and specificity. In addition, the TA bound to tumor associated vasculature that express E-selectin. Moreover, the TA selected demonstrated significant inhibition of leukocyte adhesion to E-selectin positive endothelial cells at low nanomolar concentrations. In summary, we identified antagonistic TA against E-selectin that binds to endothelial cells and interferes with leukocyte bindings at nM range. Potential applications of this TA could be for 1) inflamed tumor vasculature selective targeted delivery of therapeutic molecules or drug delivery carriers 2) the prevention of pathological diapedesis of leukocytes and/or metastatic cancer cells. We are currently investigating potential clinical applications of the TA.

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 5712.