bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2802: Selective inhibition of signal transducers and activators of transcription 3 overexpressing endometrial cancer cells, using HO-3867, a novel STAT3 inhibitor
Authors: McCann Georgia , Tierney Brent J. , Cohn David , Sudhakar Meryl , Naidu Shan , Eisenhauer Eric , Karuppaiyah Selvendiran 
Published: August 2012

Abstract
OBJECTIVE: Signal transducer and activator of transcription 3 (STAT3) proteins have important roles in cancer cell survival and proliferation. Recent studies show constitutive activation of STAT3 is associated with tumor growth and oncogenic transformation in several human cancers; however, little is known about STAT3 expression in endometrial cancer. The objectives of this study were to examine the expression of the STAT family of proteins in endometrial cancer cell lines and to evaluate the efficacy of HO-3867, a novel STAT3 inhibitor. METHODS: Expression of STAT family proteins, cell cycle and apoptotic proteins were evaluated via western blot on Ishikawa, AN3-CA, RL95-2, HEC1B, HEC-1A, and SK-UT1B human endometrial cancer cell lines. Cell viability and proliferation of these cell lines were analyzed with MTT and nucleo counter assay after treatment with increasing concentrations of HO-3867. Cell cycle analysis and apoptosis were performed using flow cytometry and annexin V staining. An ubiquitination assay was used to examine the inhibition of CDK5 degradation. Finally, STAT3 over-expression or suppression experiments were performed using wild-type STAT3 cDNA and STAT3 siRNA. RESULTS: Expression of activated STAT1, 2, 5, and 6 was inconsistent among cell lines tested, while pSTAT3 Ser727 had consistently high expression. HO-3867 decreased cell viability through induced G2/M arrest and apoptosis within 24h of treatment. HO-3867 inhibited pSTAT3 Ser727 with no change in total STAT3. This was associated with an increase in expression of cell cycle related proteins p53 and p21, a decrease in anti-apoptotic proteins Bcl2 and Bcl-XL, as well as increased cleavage of caspases. After 24h of treatment with HO-3867, 55-88% of cells were apoptotic. The downregulation of Ser727 was, at least in part, due to an accelerated inhibition of ubiquitin-dependent CDK5 degradation, as a positive regulator of STAT3 Ser727. Suppression of STAT3 expression with siRNA significantly reduced cell survival. In addition, we confirmed that over-expression of STAT3 cDNA provides resistance to HO-3867. CONCLUSION: Endometrial cancer cells express high levels of pSTAT3 Ser727. HO-3867 induces cell cycle arrest and apoptosis by targeting pSTAT3 Ser727. Our findings suggest a specific role of serine-phosphorylated STAT3 that is independent of tyrosine phosphorylation. HO-3867 may be a potential adjunct to chemotherapy and radiation in the treatment of endometrial cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2802. doi:1538-7445.AM2012-2802
Abstract 2804: Radiosensitization by the Dual PI3K/mTOR inhibitor NVP-BEZ235
Authors: Cerniglia George J. , Karar Jayashree , Koumenis Constantinos , Maity Amit 
Published: August 2012

Abstract
The PI3K/Akt pathway has been implicated in cancer progression and in the survival of cancer cells following DNA damage induced by radiation. Hence, we chose to study the radiosensitizing ability of the Novartis compound, NVP-BEZ235, a dual PI3K/mTOR inhibitor. Clonogenic cell survival assays following ionizing radiation, cell cycle analysis, immunofluorescence for γ-H2AX foci, and Western blotting were performed using standard protocols.Treatment of SQ20B head and neck squamous cell carcinoma cells and U251 glioblastoma cells with NVP-BEZ235 led to a decrease in phosphorylation of Akt at serine 473 and of S6 and 4E-BP1, both of which are downstream markers of mTOR activation. Pre-treatment with the drug (25-50 nM) led to radiosensitization of these cell lines with a dose enhancement ratio (DER) ranging from 1.32 - 1.72. Knockdown of Akt1, p110alpha, or mTOR in these cell lines, also resulted in radiosensitization, but not to the same extent as with NVP-BEZ235. Of note, treatment with rapamycin led to minimal radiosensitization of these cells. Reduced survival with NVP-BEZ235 does not result from cell cycle redistribution during the treatment intervals tested, although combining NVP-BEZ235 with radiation enhances the G2/M delay seen after radiation. We examined how cells died after radiation and found no suggestion of increased apoptosis or necrosis. We did find evidence of increased conversion of microtubule-associated protein light chain 3 (LC3)-I to LC3-II, suggestive of autophagy. In split course experiments, in which cells were either irradiated with a single dose of radiation or with two half-doses separated by time, as the interval between doses increased, so did clonogenic survival. This increase in survival was abolished by pre-treatment with NVP-BEZ235, suggesting that the drug interfered with DNA damage repair. This was confirmed by assessing levels of gamma-H2AX after ionizing radiation. Initial post-radiation levels of gamma-H2AX foci were similar in NVP-BEZ235-pretreated and control cells; however, the resolution of these foci was significantly delayed in the BEZ235-treated cells. We then examined DNA-PKcs, a protein important for DNA damage repair, and found that the drug abrogated the increased phosphorylation normally seen after radiation. These results indicate that NVP-BEZ235 is a potent radiosensitizer of HNC cells in vitro. As siRNA against either p110alpha or mTOR leads to radiosensization, both of these targets of NVP-BEZ235 may be critical mediators of its to radiosensitizing ability; however, a second mechanism involved, may be via delayed repair of DNA damage following radiation, via interference of DNA-PKcs phosphorylation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2804. doi:1538-7445.AM2012-2804
Abstract 2809: BMS-777607, a small molecule RON/MET kinase inhibitor induces polyploidy in breast cancer cells: molecular mechanism and therapeutic implication
Authors: Sharma Sharad , Zhuang Chun-Mei , Zeng Junying , Wang Minghai 
Published: August 2012

Abstract
Aberrant RON expression contributes significantly to breast cancer tumorigenic progression. This observation has provided the basis for targeting RON in potential breast cancer treatment. In the study of breast cancer tumorigenesis, we discovered that inhibition of RON by small molecule inhibitor BMS-777607 causes polyploidy followed by apoptosis in various breast cancer cells including T-47D and ZR-75-1. BMS-777607 is a tyrosine kinase inhibitor specific to RON and MET receptor tyrosine kinases and blocks cancer cell proliferation in vitro and tumor growth in xenograft model in vivo. Using breast cancer cells as the model, we observed that BMS-777607 at experimental doses induces extensive polyploidy and apoptosis in breast cancer cells. The effect of BMS-777607 has the following features. First, BMS-777607 treatment dramatically altered cell morphology, increased cell size, and created multinucleate structures. Chromosome spreading at metaphase and flow cytometric analysis confirmed polyploid cells with 6N to 16N chromosome content, indicating that abortive mitosis and endoreduplication are responsible for the observed polyploidy. Second, the effect of BMS-777607 was highly specific and dependent on RON or MET expression. MCF-7 cells that do not express RON/MET showed only low levels of polyploidy, suggesting that RON and MET expression are required for the observed polyploid activity. Third, the effect of BMS-777607 is time and dose-dependent. A substantial polyploid population of cells accumulated within 24 h of drug treatment. Continuous cycle of abortive mitosis further increased cell ploidy with increased 16N cell fractions. Moreover, an experimental dose of 500 nM is sufficient to induce polyploidy. The maximal effect occurred when BMS-777607 was used at 5.0 μM for 72 h. Fourth, polyploidy induction promoted apoptosis and senescence of breast cancer cells, which led to significant changes in cellular sensitivity towards cytotoxic activity of chemoagents. Finally, we demonstrated that Aurora B kinase is the major signaling molecule responsible for BMS-777607-induced cancer cell polyploidy. BMS-777607 inhibited Aurora B kinase activity, which affected mitosis leading to polyploidy. In summary, BMS-777607 is a potent inducer of polyploidy in breast cancer cells. By blocking RON/MET-mediated signaling events, BMS-777607 impaired Aurora B kinase activity leading to polyploidy and apoptosis. Such observations provide mechanistic and therapeutic insight in BMS-777607 targeted cancer therapy (*supported in part by NIH grant R01 CA91980 and funds from Amarillo Area Foundation).
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2809. doi:1538-7445.AM2012-2809
Abstract 2811: Preclinical evaluation of combined TKI258 and RAD001 in hepatocellular carcinoma
Authors: Wong Chi Hang , Yeo Winnie , Lui Vivian , Lau Cecilia P.Y. , Hui Connie W.C. , Chan Anthony T.C. , Chan Stephen L. 
Published: August 2012

Abstract
Hepatocellular carcinoma (HCC) is one of the most lethal cancers. Signaling pathways including AKT-mTOR axis is often dysregulated in HCC. RAD001 principally targets at the mTOR complex 1. mTOR inhibition is reportedly associated with activation of feedback loop and parallel pathways. TKI258 is a potent tyrosine kinase inhibitor targeting the FGFRs and VEGFRs, which blocks subsequent PI3K/AKT signaling pathways in cancer cells. In the current study, we aim to study the in-vitro and in-vivo effects of the drug combination with reference to the parallel and upstream pathway of AKT-mTOR axis. We have treated the HCC cell line Hep3B with TKI258 and RAD001. RAD001 could suppress the phosphorylation of down stream signal mediators of mTOR pathway including p70S6 kinase 1 (S6K) and eukaryotic initiation factor binding protein 1 (4E-BP1) and led to G1 phase arrest. The results demonstrated a significant increase in suppression of cell proliferation in vitro with the combination of TKI258 (300nM) and RAD001 (either 200nM or 200pM) compared with either drug alone. Although the addition of the TKI258 only slightly suppressed the AKT positive feedback loop induced by RAD001, the combination of drugs could significantly suppress the phosphorylation of mTOR (Ser2448), ERK1/2 (Ser217/221) and p38 (Thr180/Tyr182) as well as their endogenous protein expression levels. The expression levels of FGFR1 and FGFR2 were also suppressed. The overall protein reduction was due to the synergistic inhibition of p70S6 (Ser240/244) and 4E-BP1 (Ser65) phosphorylation, which indicated a strong suppression in translation and protein synthesis. Pro-caspases 3 and PARP cleavage were not observed at 24 hours and only slightly detected at 48 hours post-treatment, suggesting that the drug combination did not further increase cytotoxic effects but mainly increased in cytostatic arrest ability. In Hep3B derived xenograft model, TKI258 (15mg/ml) and RAD001 (2.5mg/kg) had shown a synergistic inhibition of tumor growth in volume and weight. In addition, there was a significant reduction in microvessel density (MVD) in the xenograft, which indicated an improved effect in angiogenesis inhibition. Our data showed that the combination of RAD001 and TKI258 were active in controlling HCC proliferation via double inhibition of both AKT-mTOR axis and its parallel pathway. Acknowledge: The works are supported by Novartis Oncology.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2811. doi:1538-7445.AM2012-2811
Abstract 2812: mTOR kinase mediates dissemination and colonization of breast cancer metastasis
Authors: Janes Matthew R. , Guo Xin , Elia Marikka , Staunton Jocelyn , Jessen Katti , Rommel Christian , Liu Yi 
Published: August 2012

Abstract
Background: Early events of metastatic dissemination arise from the ability of tumor cells to acquire a number of biological changes which allow for their survival in distal microenvironments. Among the early events that initiate disseminated tumor populations include epithelial-to-mesenchymal transition (EMT) and increased potential for invasion that will ultimately lead to colonization of distal sites. The PI3K/mTOR pathway has been linked to clinic-pathalogical features of invasion and metastasis of multiple tumor types. Results: We sought to investigate using both in vitro and in vivo models of metastasis a panel of PI3K/mTOR selective inhibitors, in which INK128, a selective mTOR kinase inhibitor in clinical development was included. Using live-cell time lapse imaging experiments to monitor cell migration and invasion we found that INK128 significantly inhibited motility and velocity of metastatic breast cancer models in wound assays and decreased the ability of tumor cells to migrate through membranes and matrigel. The ability of INK128 to selectively inhibit tumor cell migration in vitro prompted us to assess whether INK128 can prevent tumor dissemination in vivo. In metastatic breast cancer xenograft models we monitored the growth of tumors implanted in mammary fat pads (MFP) and metastatic dissemination by serial noninvasive whole body bioluminescent imaging. We first assessed and characterized the degree of spontaneous metastasis to the lung, liver, auxillary lymph nodes, chest cavity of mice and subsequently the effect of mTOR kinase inihibition on primary tumor growth on the MFP versus overt metastatic dissemination upon daily, oral treatment with INK128. We show that INK128 blocked drastically metastatic spread in a dose-dependent manner without significantly affecting the growth of primary tumors. Interestingly, we found that INK128 did not affect the ability of breast cancer cells to enter into the lungs following an alternative experimental lung metastasis model by lateral tail vein injection but INK128 greatly diminished the capacity of breast cancer cells to subsequently colonize and expand. Conclusion: Our results position mTOR on a metastasis-sustaining axis that engages downstream pathways to support the biological machinery of migration, invasion, and fitness of initiating breast cancer cells during the establishment of thoracic metastases.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2812. doi:1538-7445.AM2012-2812
Abstract 2813: Modulation of Signal Transducer and Activator of Transcription 3 by emodin through the induction of a phosphatase leads to the suppression of HCC growth in orthotopic mouse model
Authors: Shanmugam Muthu K. , Ong Tina H. , Peramaiyan Rajendran , Subramaniam Aruljothi , Hui Kam M. , Sethi Gautam 
Published: August 2012

Abstract
Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide and the third cause of global cancer mortality. Activation of signal transducer and activator of transcription 3 (STAT3) is commonly encountered in tumor cells and is a critical mediator of oncogenic signaling in HCC and controls the expression of several genes involved in proliferation, survival, metastasis and angiogenesis. Current drug-targeted therapies, besides being expensive, are associated with serious side effects and morbidity. Thus, novel agents that can suppress STAT3 activation have potential for both prevention and treatment of HCC. In this study, we tested an agent, emodin, a quinone, for its ability to suppress STAT3 activation in HCC cells and in nude mice model along with prospectively testing the hypothesis of STAT3 inhibition in a virtual predictive functional proteomics tumor pathway technology platform. We present evidence that emodin can inhibit both constitutive and inducible STAT3 activation in HCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, and Janus-activated kinase-2. Vanadate treatment reversed the emodin induced down-regulation of STAT3 activation, suggesting the involvement of SHP1. Indeed, we found that emodin induced the expression of tyrosine phosphatase SHP1 and deletion of SHP1 by small interfering RNA abolished emodin ability to inhibit STAT3 activation and provide new evidence on the critical role of SHP1 in mechanism of action of emodin. Emodin inhibited proliferation, and produced a synergistic apoptotic effects in the presence of paclitaxel and doxorubicin in HCC cells. When administered i.p., emodin inhibited the growth of human HCC orthotopic tumors in male athymic nu/nu mice. In conclusion, results from experimental and predictive studies suggest that emodin exerts its anti-proliferative and pro-apoptotic effects through suppression of STAT3 signaling cascade in HCC both in vitro and in vivo.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2813. doi:1538-7445.AM2012-2813
Abstract 2815: Sylvestrol inhibits protein synthesis by downregulating the AKT/mTOR pathway
Authors: Yang Jilai , Shen Qi , Newman David J. , Kinghorn A. Douglas , Swanson Steven M. 
Published: August 2012

Abstract
Silvestrol, a cyclopenta[b]benzofuran lignan present in the fruits and twigs of the tropical tree Aglaia foveolata Pannell (Meliaceae), is toxic to human cancer cell lines in culture with a potency similar to those of FDA approved anticancer chemotherapeutic agents. We report here that silvestrol has a mean GI50 of approximately 3 nM in the 60 cell-line panel of human cancer cell lines maintained at the National Cancer Institute. Furthermore, silvestrol is at least as effective as FDA-approved anticancer agents in the treatment of human cancer cells in vivo when tested in the hollow fiber assay or the inhibition of human tumor xenograft tumors propagated in immunedeficient mice. Others as well as our group have reported that silvestrol inhibits protein biosynthesis specifically without affecting the cellular production of either RNA or DNA. Pelletier and colleagues have shown that silvestrol impairs the ribosome recruitment step of translation initiation by affecting the composition of the eukaryotic initiation factor (eIF) 4F complex. In the present study, we test the hypothesis that disruption of protein synthesis by silvestrol can impact cell signaling pathways upstream of translation. Human colon cancer cells designated HT-29 were exposed to silvestrol at concentrations as high as 100 nM for as long as 48 h prior to harvest and evaluation by immunoblot. Protein signaling molecules known to regulate the protein synthesis machinery were evaluated for their abundance and state of phosphorylation as a function of silvestrol exposure. We observed down-regulation of the p110α catalytic subunit of PI3K, which phosphorylates PIP2 to PIP3. PIP3 then recruits PDK1 and AKT to the plasma membrane, where PDK1 can phosphorylate AKT. A decrease in the amount of PDK1 protein and a significant decrease in phosphorylation of AKT at ser 473 occurred. Moreover, a decrease in both the abundance and phosphorylation of mTOR was evident, which is a key component of mTORC2. Consistent with these findings, phosphorylation of AKT at thr 308 was significantly reduced. Finally, silvestrol exposure resulted in a decrease in phosphorylation of the S6 ribosomal protein serine 235/236. These data indicate that silvestrol treatment can disrupt key signaling pathways leading to protein synthesis production in human cancer cells. This work was supported by NIH grants U01 CA52956 and P01 CA125066.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2815. doi:1538-7445.AM2012-2815
Abstract 2820: Vorinostat abrogates ridaforolimus-induced activation of Akt in synovial sarcoma cells: A possible rationale for their synergism
Authors: Morgan Sherif S. , Cranmer Lee D. 
Published: August 2012

Abstract
Background: Curative treatments for patients with metastatic synovial sarcoma (SS) do not exist and such patients have a poor prognosis. Previously, we demonstrated that the combination of the mTOR inhibitor ridaforolimus and the HDAC inhibitor vorinostat exhibited synergism in a variety of cell lines. Here, we explore whether the Akt pathway is potentially involved in mediating the synergistic effects of ridaforolimus and vorinostat. Methods: Two SS cell lines (HS-SY-II and SYO-I) were treated with the single agents or with combinations of ridaforolimus and vorinostat. After 72 hours, cell viability was measured using the cell proliferation assay (MTS). Combination Indices (CI) were calculated to determine whether each combination was synergistic, additive, or antagonistic. Western Blot analysis assessed alterations in total and phospho-Akt protein levels in response to drug treatment. Results: Ridaforolimus IC50 was 10.9nM in HS-SY-II and 23.1nM in SYO-I; vorinostat IC50 was 440nM in HS-SY-II and 561nM in SYO-I. CI were 0.28 and 0.63 in HS-SY-II and SYO-I, respectively, indicating synergism between the two agents. The ridaforolimus/vorinostat combination was assessed in other tumor types, including osteosarcoma (U2OS), metastatic melanoma (Stew1 and Stew2), pancreatic cancer (Panc1 and BxPC3), and lung cancer (A549). The combination was synergistic in all cell lines: CI ranged from 0.37 to 0.77, except in Panc1, where it was additive (CI=0.92). As previously observed with other mTOR inhibitors, ridaforolimus alone increased pAkt-ser473 levels in SS cell lines; this effect was abrogated by the addition of vorinostat. Conclusions: The combination of ridaforolimus and vorinostat demonstrates in vitro synergism in SS as well as in a variety of other tumor types. The addition of vorinostat prevented ridaforolimus-induced Akt activation, a possible mechanism of resistance to mTOR inhibition. Adding HDAC inhibition to mTOR inhibitors may be a route to circumvent Akt-mediated resistance to mTOR inhibitors. Our results also indicate that this combination may demonstrate broad anti-neoplastic activity.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2820. doi:1538-7445.AM2012-2820