bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2625: MGCD0103, an oral isotype-selective HDAC inhibitor, has antitumor activity via the induction of the expression of Annexin A1 on AML1/ETO AML in vitro and in vivo
Authors: Nameki Daisuke , Masuko Norio , Fujita Ryouto , Sugiura Shin , Yamamoto Yasuji , Minamiguchi Kazuhisa , Matsuo Ken-Ichi
Published: June 2012

MGCD0103 is a non-hydroxamate and an orally available isotype-selective HDAC inhibitor (HDACi) whose clinical activity has been shown in multiple phase II trials in patients with relapsed or refractory Hodgkin lymphoma, high-risk myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). It has previously been shown that FK-228, class I selective HDACi, and SAHA, isotype-nonselective HDACi, activate apoptosis through induction of pro-apoptotic protein annexin A1 on t(8;21) translocated AML cells which produce AML1-ETO fusion protein (AML1/ETO AML). To determine whether the existence of t(8;21) translocation in AML affect on the efficacy of MGCD0103, we explored the action of MGCD0103 on anti-tumor activity in AML1/ETO AML and AML1/ETO-negative AML xenograft models in mice in vivo and investigated the putative mechanism of the efficacy.MGCD0103 was orally administrated to the NOD SCID mice implanted with AML1/ETO AML xenograft or AML1/ETO-negative AML xenograft using an intermittent dosing regimen (3 times a week) for 3 weeks. Tumor volume was calculated during the treatment and tumor weight at final date was measured for final evaluation. In addition, we measured not only the activity of apoptosis related factor, caspase-3/7, but also the expression of pro-apoptotic protein annexin A1 that induced by MGCD0103 in vitro and in vivo. Further understanding of the mechanism of MGCD0103, we assessed the acetylated histone in the promoter region of annexin A1 using ChIP assay in vitro whether its induction is derived from the histone acetylation activity of MGCD0103. MGCD0103 showed a strong growth inhibition of the tumor in the AML1/ETO AML xenograft. There were significant decreases in the AML1/ETO AML tumor volume and weight in the MGCD0103 treated group compared with the control group, but not in the AML1/ETO-negative AML xenograft. Caspase-3/7 was strongly activated and the expression of annexin A1 was significantly induced in the MGCD0103 treated AML1/ETO AML cells. In addition, histone of annexin A1 promoter region in AML1/ETO AML tended to be acetylated more than the AML1/ETO-negative AML cells by MGCD0103. These data possibly indicate that the strong anti-tumor effect was derived from the direct effect of MGCD0103 that leads apoptosis of the AML1/ETO AML cells through the induction of acetylation of annexin A1 promoter. Selection of AML patients with t(8;21) translocation may leads good therapeutic outcome of MGCD0103 in AML treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2625. doi:10.1158/1538-7445.AM2011-2625
Abstract 2628: Antitumor activity of MPC-3100, a synthetic Hsp90 inhibitor, in combination with erlotinib and sorafenib
Authors: Baichwal Vijay R. , Brown Brita , Wettstein Daniel , Papac Damon I. , Mather Gary G. , Carlson Robert O.
Published: June 2012

Introduction: MPC-3100 is a fully synthetic, orally bioavailable, Hsp90 inhibitor in clinical development. It is active as a single agent in xenograft models with many cancer types including colon, gastric, ovary, prostate, breast, lung and myeloid leukemia. We evaluate here the activity of MPC-3100 in combination with erlotinib or sorafenib in xenograft models.

Methods: Three to five million cells, depending on cell-type, were implanted subcutaneously into athymic mice (nu/nu) for tumor studies. Dosing was initiated when median tumor volume was >100 mm3. All compounds were dosed orally, once daily. MPC-3100 (100 mg/kg) and erlotinib (100 mg/kg) were dosed on Days 1-21 and sorafenib (60 mg/kg) was dosed on Days 1-9.

Results: Anti-tumor activity for the combination of MPC-3100 and erlotinib was compared to that of the single agents in a lung cancer (A549) xenograft model sensitive to EGFR inhibition. Administration of MPC-3100 or erlotinib resulted in 52% and 64% tumor growth inhibition (TGI), respectively relative to vehicle by the end of dosing on Day 19. By contrast, the combination of MPC-3100 and erlotinib resulted in 30% tumor regression over the same period. Thus the combination of MPC-3100 and erlotinib was more effective at inhibiting tumor growth than either agent alone (p<0.05). The combined anti-tumor activity of MPC-3100 and sorafenib was compared to administration of the single agents in a xenograft model with the melanoma cell line A375 that harbors the activating B-raf mutation, V600E. The median tumor volume (MTV) of the cohorts dosed with vehicle, MPC-3100 or sorafenib as single agents was comparable and increased by 4.8-, 6.4- and 8.2-fold, respectively by the end of dosing on study Day 20, whereas MTV of the cohort dosed with a combination of MPC-3100 and sorafenib increased by only 1.6-fold. The combination of MPC-3100 and sorafenib resulted in 66% tumor growth inhibition relative to vehicle on Day 20 and was more effective at inhibiting tumor growth than single agent (p<0.05).

Conclusions: The combination of MPC-3100 with erlotinib or sorafenib shows greater anti-tumor activity than either agent alone. Thus, in addition to its broad activity in xenograft models as a single agent, MPC-3100 has the potential to be combined with other targeted therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2628. doi:10.1158/1538-7445.AM2011-2628
Abstract 2632: SAHA loosens chromatin structure and increases DNA damage in human lung cancer cells induced by arsenic trioxide
Authors: Chien Chia-Wen , Yao Ju-Hsien , Chang Shih-Yu , Lee Pei-Chih , Lee Te-Chang
Published: June 2012

The efficacy of arsenic trioxide (ATO) against acute promyelocytic leukemia (APL) and relapsed APL has been well-documented. ATO may cause DNA damage through the generation of reactive oxygen intermediates. Histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), modulates gene or protein expression via histone dependent or independent pathway that may result in chromatin decondensation, cell cycle arrest, differentiation, and apoptosis. The objective of this study is to investigate whether ATO and SAHA could synergistically enhanced cell killing to cancer cells. The present studies showed that combined treatment with ATO and SAHA results in enhanced suppression of non-small cell lung carcinoma (NSCLC) H1299 cells in vitro and in xenograft mouse model. By analyzing the annexin V positive cells, apoptotic cell death is significantly enhanced in combined treatment. At the doses used, ATO does not interfere with the cell cycle progression, whereas SAHA induces the expression of p21WAF1/CIP1 and leads to G1 arrest. By the aid of Comet assay, we demonstrated that ATO induces DNA breaks in H1299 cells, but not SAHA. However, co-treatment with SAHA and ATO significantly increases ATO-induced DNA damage. Moreover, SAHA enhances acetylation of histone H3 and sensitize genomic DNA to DNase I digestion. Our present results suggest that SAHA may result in chromatin relaxation, and lead to cells become more susceptible to ATO for causing DNA damage. Therefore, combination of SAHA with ATO may provide effective approach to treatment of lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2632. doi:10.1158/1538-7445.AM2011-2632
Abstract 2635: CBP501-calmodulin binding contributes to sensitizing tumor cells to CDDP and BLM
Authors: MINE NAOKI , Yamamoto Sayaka , Saito Naoya , Kufe Donald W. , VonHoff Daniel D. , Kawabe Takumi
Published: June 2012

CBP501 is an anti-cancer drug candidate currently under the Phase II clinical trials on non-small cell lung carcinoma (NSCLC) and malignant pleural mesotherioma (MPM). CBP501 was originally described as a unique G2 checkpoint-directed agent that binds to 14-3-3, inhibiting the actions of Chk1, Chk2, MAPKAP-K2, or C-Tak1. However, unlike a G2 checkpoint inhibitor, CBP501 clearly enhances the G2/M accumulation induced by cisplatin (CDDP) or bleomycin (BLM) at low dose and short exposure to tumor cells. It does not affect the accumulation at G2/M by radiation, doxorubicin or 5-FU treatment in the same condition. Our recent findings point to an additional mechanis of action (MOA) for CBP501.

The enhanced G2/M accumulation by CDDP results from increased intracellular platinum concentration, which leads to increased binding of platinum to DNA. The observed CBP501-induced platinum accumulation is negated in the presence of excess Ca2+. Some calmodulin (CaM) inhibitors behave similarly to CBP501. But the therapeutic window of CBP501 was broader than CaM inhibitors. Furthermore, analysis by surface plasmon resonance (SPR) reveals a direct, high-affinity molecular interaction between CBP501 and CaM (Kd=4.62×10−8M) that is reversed by Ca2+, whereas the Kd for the complex between CBP501 and 14-3-3 is some 10-fold weaker and is Ca2+-independent. We conclude that calmodulin inhibition plays important role in the activity of CBP501 in sensitizing cancer cells to CDDP or BLM. This report presents the prospects for the development of a new class of anti-cancer drugs through the addition of unique calmodulin inhibition.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2635. doi:10.1158/1538-7445.AM2011-2635
Abstract 2645: PEITC induces cell death in melanoma cells through redox mechanisms
Authors: Ahmed Kausar Begam Riaz , Feng Li , Huang Peng
Published: June 2012

Melanoma is one of the deadliest types of cancers accounting for about 80% of skin cancer deaths. Reactive oxygen species (ROS), produced by the mitochondrial respiratory chain and other biochemical mechanisms, play a critical role in melanoma progression through activation of transcription factors AP-1 and NF- κB and loss of E-cadherin. However, a further elevated level of ROS in cells, beyond a certain cellular threshold, may lead to mitochondrial damage, cytotoxicity and subsequent cell death. Hence, increasing ROS levels by either activating a ROS-generating enzyme or by depletion of antioxidants is a plausible strategy to induce cell killing in melanoma cells. The natural compound β-phenylethyl isothiocyanate (PEITC) found in cruciferous vegetables exhibits significant antitumor activity. Recent studies demonstrated that PEITC selectively induced cancer cell death by disabling the glutathione antioxidant system. Based on these observations, we hypothesize that PEITC may preferentially eliminate melanoma cells through ROS-mediated mechanism due to the increased basal ROS levels in melanoma cells and their high dependence on glutathione. To test this hypothesis, the cytotoxic effect of PEITC was tested in a panel of melanoma cell lines in comparison with normal melanocytes. Our results demonstrated that PEITC had time- and concentration-dependent antiproliferative effect in melanoma cells. The inhibitory effect is melanoma specific, since PEITC had minimum cytotoxic activity in normal melanocytes. Further analysis of ROS by FACS using the fluorescent dye DCFDA revealed that this cell death was primarily due to increased ROS accumulation triggered by PEITC-induced depletion of cellular glutathione. This aberrant increase in ROS caused mitochondrial membrane damage, as determined by biochemical analysis using Rhodamine 123, and subsequent cell death through apoptosis. Importantly, PEITC was very effective in melanoma cells, which exhibited resistance to standard anti-tumor drugs like temozolomide (TMZ) and carmustine (BCNU). Our study suggests that PEITC may be an effective anti-melanoma therapeutic agent that warrants further pre-clinical and clinical investigation. Our work is now directed towards identifying other ROS related cellular mechanisms that can be exploited to increase the therapeutic specificity and sensitivity of PEITC in melanoma cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2645. doi:10.1158/1538-7445.AM2011-2645
Abstract 2651: Cucurbitacin I (JSI-124) activates the JNK signaling pathway leading to transcriptional up-regulation of vascular endothelial growth factor in B leukemia cells
Authors: Ishdorj Ganchimeg , Johnston James B. , Gibson Spence B.
Published: June 2012

JSI-124 (Cucurbitain I) is a biochemical compound isolated from the herbal plant families, which have been used as folk medicines for centuries in Asian countries. The molecular mechanisms for this inhibitor acts primarily through STAT3 inhibition in many tumors, including chronic lymphocytic leukemia. However, other molecular targets of JSI-124 are not fully understood. The objective of this study was to determine the molecular targets of JSI-124 beyond STAT3. Chemotherapeutic drugs often induce a stress response in cancer cells. One of early stress response pathways is the c-Jun N-terminal kinase (JNK) pathway. Herein, we show that JSI-124 activates JNK and increased the expression of c-Jun protein in the B leukemia cell lines BJAB, I-83 and NALM-6. Interestingly, the inhibition of the JNK signaling pathway failed to effect JSI-124 induced cell cycle arrest or apoptosis in these leukemia cells but repressed c-Jun level. Furthermore, JNK activation also failed to effect JSI-124 inhibition of STAT3 phosphorylation in these cells. It is known that one of the important factors involved in JNK signaling is Vascular Endothelial Growth Factor (VEGF). We found that JSI-124 treated BJAB cells showed an increased in mRNA and protein level in VEGF in BJAB, I-83 and NALM-6 cells. Knockdown of c-Jun expression and inhibition of JNK activation significantly blocked JSI-124 induced VEGF expression. Taken together, our data demonstrate that JSI-124 activates JNK signaling pathway leading to VEGF expression independent of inhibition of STAT3 activation. This could lead to increased angiogenesis in B leukemia cells treated with JSI-124.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2651. doi:10.1158/1538-7445.AM2011-2651
Abstract 2653: Nelfinavir induces apoptosis in hormone-resistant prostate cancer cells through inhibition of regulated intramembrane proteolysis of SREBP-1 and ATF6
Authors: Guan Min
Published: June 2012

We previously reported that nelfinavir-induced apoptosis in liposarcoma is a direct result of regulated intramembrane proteolysis (RIP) inhibition mediated through inhibition of site-2 protease (S2P) activity. We now report similar effects in hormone-resistant prostate cancer (HR-PC) cells. Nelfinavir-mediated RIP inhibition leads to accumulation of unprocessed sterol regulatory element binding protein-1 (SREBP-1) and activating transcription factor 6 (ATF6). This results in endoplasmic reticulum (ER) stress and inhibition of the unfolded protein response (UPR), which leads to autophagy and caspase activation. Confocal microscopy and proliferation studies demonstrate that nelfinavir inhibits the nuclear translocation of SREBP-1-EGFP and ATF6-EGFP fusion proteins, and reduces PC proliferation, similar to the situation observed in site-1 protease (S1P) and S2P-siRNA knockdown cells. Western blotting in nelfinavir and S1P and/or S2P-siRNA knockdown cells confirms accumulation of precursor SREBP-1 and ATF6. Treatment of PC cells with DCI, an S1P inhibitor did not affect SREBP-1 processing. In contrast, 1,10-phenanthroline, an S2P inhibitor, reproduces the molecular and biological phenotype observed in nelfinavir-treated HR-PC cells. These results are consistent with the hypothesis that S2P is a target of nelfinavir. These findings, together with our previous report, provide new insight into the mechanism of nelfinavir-mediated induction of ER stress and cell death in cancer, and are the first to report targeting S2P therapeutically for cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2653. doi:10.1158/1538-7445.AM2011-2653
Abstract 267: E2F1 regulates human TRAIL promoter and mediates Interferon alpha 2a response
Authors: Kunigal Sateesh S. , Joshi Bharat , Chellappan Srikumar S.
Published: June 2012

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/APO2L) is a member of the TNF gene superfamily that induces apoptosis upon engagement of cognate death receptors. While TRAIL is relatively non-toxic to normal cells, it selectively induces apoptosis in many transformed cells and has been explored as an anti-cancer agent. Earlier studies have shown the upstream region of human TRAIL gene, contain NFAT, AP-1, and Sp1 binding sites which have been shown to regulate expression of multiple cytokines, but the transcriptional regulation of TRAIL has not yet been elucidated in detail. An examination of the human TRAIL promoter showed the presence of five binding sites for the E2F transcription factors. E2F1 is a transcription factor that plays a well-documented role in cell cycle regulation, differentiation and senescence. In addition to its proliferative effects, E2F1 has been shown to have potent apoptotic properties as well, under appropriate conditions. E2F1 can induce apoptosis via several p53-dependent or -independent mechanisms, either through direct transactivation of proapoptotic genes such as p73, apaf-1 (apoptosis protease-activating factor 1) and caspases or transcriptional repression. Studies presented here show that the human TRAIL promoter is E2F responsive in multiple lung cancer cell lines. Chromatin immunoprecipitation assays showed the recruitment of E2F1 as well as Rb to the TRAIL promoter and transient transfection of E2F1 could induce the expression of a TRAIL-luciferase reporter construct. TRAIL could be repressed by Rb, but this repression could be overcome by the transient transfection of ASK-1, Raf-1 or p38 kinases as well as cycling D or E, suggesting that this promoter is responsive to extracellular signals that can regulate Rb function. It has been shown that stimulation of natural killer cells by Interferon alpha-2a leads to upregulated TRAIL expression. We find that Interferon alpha 2a (IFN α 2a) stimulated lung cancer cell lines exhibited high TRAIL luciferase activity and depletion of E2F1 by siRNA techniques prevented the induction of TRAIL. These results suggest that E2F1 as a critical regulator of TRAIL expression and might facilitate death-receptor-mediated apoptosis. These observations raise the possibility that E2F-mediated regulation of TRAIL might have effects on the immune response of lung cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 267. doi:10.1158/1538-7445.AM2011-267
Abstract 2670: Decreased expression of miR-302 contributes radioresistance of breast cancer cells
Authors: Liang Zhongxing , Guo Donna , Votaw John R. , Wang Ya , Shim Hyunsuk
Published: June 2012

Radiotherapy is a common treatment strategy for many solid tumors, including breast cancer. Unfortunately, solid tumors can be resistant or develop resistance to radiotherapy. Though many studies have been conducted to further elucidate the mechanisms of radioresistance, they remain largely obscure due to the complex genetic cellular response to radiation and involvement of a large number of genes. MicroRNA, a recently discovered class of small, functional, non-coding RNA, is one of such class of potential regulators. A single microRNA can target a large number of genes and regulate several signal pathways simultaneously. Thus, miRNAs may be involved in the complex radioresistance of tumor cells. In the present study, we characterized miR-302 family members (miR-302s) pre-clinically as novel biomarkers for radiotherapy resistance. Our results showed that miR-302s were downregulated in irradiated breast cancer cells. Furthermore, we found, with a bioinformatic analysis, that AKT and RAD52, two critical regulators of radioresistance, are the predicted targets of miR-302s. Additionally, the expression levels of miR-302a were inversely consistently with those of AKT and RAD52. More promisingly, our data have demonstrated that miR-302a mimics sensitized breast cancer MDA-MB-231 cells to radiation therapy and reduced the expression of AKT and RAD52. Collectively, loss of miR-302s may be involved in the radioresistance of breast cancer cells, mainly through the release of repression of AKT and RAD52. Thus, our findings suggest that decreased expression of miR-302s contributes to radiotherapy-resistance and restoration of miR-302 baseline expression sensitizes breast cancer cells to radiotherapy. These data suggest that miR-302s may be potential sensitizers to radiotherapy and represent a novel strategy for radiotherapy of breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2670. doi:10.1158/1538-7445.AM2011-2670
Abstract 2674: Radio-sensitizer eluting nanoporous coatings on fiducials markers: Biological in-situ dose-painting for IGRT
Authors: Sridhar Srinivas , Nagesha Dattatri , Tada Dayane , Kumar Rajiv , Makrigiorgos G. Mike , Cormack Robert
Published: June 2012

Image-guided radiation treatments routinely utilize implantable devices, such as radio-opaque fiducials or brachytherapy spacers, for improved spatial accuracy. We study the hypothesis that the therapeutic efficiency of IGRT can be further enhanced by biological in-situ dose painting (BIS-IGRT) using local delivery of radiosensitizers embedded within nanoparticles and nanoporous polymer matrices coating gold fiducial markers. Biocompatible polymers loaded with model molecules were coated as a thin film on gold fiducials. The nanoporous morphology of the polymer coatings allowed the controlled release of the molecules and nanoparticles. Two experimental approaches were studied: (i) a free drug release system Doxorubicin, a hydrophilic drug in Poly(methyl methacrylate (PMMA) coating and (ii) Poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles loaded with Coumarin-6, a model for a fluorescent hydrophobic drug, in a chitosan matrix applied as fiducial coating. Temporal release kinetics measurements in buffer were carried out using fluorescence spectroscopy. For flat gold films and gold fiducials coated with Doxorubicin in PMMA matrix, an initial release of Dox within the first few hours was followed by a sustained release over the course of next 3 months. Release of Dox from within PMMA matrix is dependent on the concentration of Dox, ratio of PMMA/Dox, thickness of PMMA/Dox coating on gold surface. The release profile of coumarin-6 loaded nanoparticles from chitosan film on gold fiducials showed a continuous release of NPs from the coating during forty days. (63±10)% of NPs were released in twenty days. After that, the release became slower and additional 37% of release was observed after twenty-days. Spatial release profiles in an agarose phantom were also measured and compared with release kinetics models. Results show that dosage and rate of release of these radiosensitizers can be precisely tailored to achieve the desired release profile for BIS-IGRT.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2674. doi:10.1158/1538-7445.AM2011-2674
Abstract 2715: Host genomic environment determines HTLV-1 clone size in vivo
Authors: Gillet Nicolas , Malani Nirav , Melamed Anat , Gormley Niall , Carter Richard , Bentley David , Berry Charles , Bushman Frederic , Taylor Graham , Bangham Charles
Published: June 2012

HTLV-1 persists by driving clonal proliferation of infected T-lymphocytes. A high proviral load predisposes to the inflammatory and malignant diseases associated with HTLV-1. Yet the reasons for the remarkable variation within and between individuals in the size of HTLV-1-infected clones remain unknown. We devised a high-throughput protocol to map the genomic location and quantify the abundance of >91,000 distinct integration sites from 61 HTLV-1+ individuals and >2,100 sites from in vitro infection. We show that a typical HTLV-1-infected host carries between 500 and 5000 distinct integrated proviral clones. We demonstrate that negative selection dominates during chronic infection, favouring survival of proviruses integrated in transcriptionally silenced DNA: this selection is significantly stronger in asymptomatic carriers. The high proviral load characteristic of HTLV-1-associated inflammatory disease results from a larger number of integrated proviruses and not as previously believed from a difference in clonality. The abundance of surviving integrated proviruses is determined by genomic features of the flanking DNA and the transcriptional orientation of the provirus relative to the nearest host gene. HTLV-1 clonal expansion in vivo is favoured by orientation of the provirus in the same sense as the nearest host gene.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2715. doi:10.1158/1538-7445.AM2011-2715
Abstract 2716: Overexpression of p16INK4a in Merkel cell carcinoma
Authors: Yu Dawen , Zhang Hong , Carrigg Alison , Wang-Rodriguez Jessica , Liu Yu-Tsueng
Published: June 2012

Merkel cell polyomavirus (MCV) is a recently discovered human oncogenic virus. The majority of Merkel cell carcinomas (MCC) have been found to be infected with MCV. The MCV large T antigen (LTA) consists of an Rb binding motif that is functionally analogous to the E7 protein of high-risk human papillomavirus (HPV) types (eg. 16 and 18). It has been well documented that inactivation of Rb leads to overexpression of p16INK4a. Clinically, immunohistochemistry for p16INK4a has proven useful in the diagnosis of HPV driven epithelial malignancies including cervical as well as head and neck cancers. The present study explores the relationship between MCV infection and p16INK4a expression using an in vitro cell culture system and 10 clinical specimens of MCC that have been diagnosed at the San Diego VA Hospital over a 21 year period. First, IMR-90 cells were transfected with MCV LTA plasmids, which carry either wild-type or mutant Rb binding motif for immunofluorescence analysis. Only cells transfected with wild-type, but not mutant LTA, were associated with p16INK4a up-regulation. Furthermore, a strong positive correlation was established between MCV LTA and p16INK4a expression in formalin-fixed, paraffin-embedded MCC samples by immunohistochemical staining using p16INK4a and MCV LTA specific monoclonal antibodies, and real-time PCR to detect MCV with two pairs of primers. In conclusion, strong association between p16INK4a expression and MCC suggests that the MCV and HPV related carcinomas share some common oncogenic pathways. In addition, p16INK4a positivity can be a useful diagnostic tool in differentiating MCC from other small blue cell tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2716. doi:10.1158/1538-7445.AM2011-2716
Abstract 2717: Detection of Merkel cell polyomavirus in chronic lymphocytic leukemia cells by fluorescence in situ hybridization (FISH)
Authors: Speel Ernst-Jan M. , Haugg Anke , Pantulu Naga Deepa , Pallasch Christian , Kurz Anna K. , Kassem Ahmad , Frenzel Lukas , Sodenkamp Sebastian , Kvasnicka Hans M. , Wendtner Clemens , Zur Hausen Axel
Published: June 2012

Background: Merkel cell polyomavirus (MCPyV) is detected in approximately 80% of Merkel cell carcinomas (MCC). A number of previous studies have shown that MCC patients are at a significantly increased risk to develop chronic lymphocytic leukemia (CLL) and vice versa. Until recently, clonal integration and truncating mutations of the Large T antigen (LTAg) of MCPyV were restricted to MCC. We have recently reported the presence of the MCPyV in highly purified tumor cells of CLL (n = 19/70, 27.1%) (Blood. 2010 Sep 3). Of these, six revealed a novel 246 bp deletion in the helicase gene of the LTAg. The presence of MCPyV was confirmed by immunohistochemistry.

Material and Method: Here we aimed to determine the presence of MCPyV by fluorescence in situ hybridization (FISH) analysis in CLL cells in order to evaluate whether MCPyV was integrated or episomal. For this purpose we performed FISH analysis as previously described (Int J Cancer. 2005, 115:419-428) using the MCPyV genome as FISH probe. We tested 2 of the previously reported MCPyV positive CLL cases (EDTA decalcified bone marrow trephines) and MCPyV-positive MCC (n = 5). In addition, we tested MCPyV-negative tumors, e.g. breast and colon cancers. All tissues were formalin-fixed and paraffin-embedded.

Results: Specific MCPyV DNA by FISH analysis was detected in the nuclei of MCPyV-positive CLL and MCC cells. In contrast to particularly punctate FISH signals in MCC indicating viral integration, the nuclear FISH signals of the CLL cases revealed especially granular signals, indicative for integrated MCPyV DNA together with transcribed viral RNA (Int J Cancer. 2008, 122:2656-2664). No signals were obtained by MCPyV FISH in breast or colon cancer specimens.

Conclusion: The specific detection of MCPyV in CLL cells further supports our previous report of a possible involvement of MCPyV in a significant subset of CLL. The specific but rather granular nuclear FISH signals in MCPyV positive CLL cells needs further study to evaluate if it is also generated by co-existing episomal virus copies, by viral RNA or by the decalcification process. In addition, more CLL cases will be analyzed for the presence of MCPyV.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2717. doi:10.1158/1538-7445.AM2011-2717
Abstract 2720: Cidofovir modulates HPV E6 and E7 as well as p53, Rb and MDM2 in HPV16 naturally transformed head and neck squamous cell carcinoma and enhances chemosensitivity to Cisplatin
Authors: Park Jung Je , Kommareddi Pavan K , Nair Thankam S. , Seo Ji Hyun , Jeon Sea-Yuong , Kim Sang Yoon , Prince Mark E. , Bradford Carol R. , Carey Thomas E.
Published: June 2012

Purpose: The increasing incidence of oropharyngeal head and neck squamous cell carcinoma (HNSCC) is largely associated with sexually transmitted infection with high risk human papillomavirus (HPV), particularly HPV16. Cidofovir is an acyclic nucleoside phosphate that has broad antiviral activity against DNA viruses and is used clinically in recurrent respiratory papillomatosis. It is not known whether Cidofovir has any therapeutic effects on naturally transformed and non-transformed HNSCC cell lines.

Experimental Design: We investigated the effects of Cidofovir on naturally HPV16 transformed HNSCC cell lines, and compared these with the effects on non-transformed HNSCC cell lines from similar tumor sites. We performed RT-PCR in HPV16 transformed cell lines to evaluate the effect of Cidofovir on HPV16 E6 and E7 gene transcription. Modulation of p53, Rb, MDM2, p21(WAF1), and p16 protein levels were studied by Western blot analysis. To evaluate chemosensitivity in the cells, we pretreated the tumor cell with Cidofovir followed by Cisplatin and then assessed cell cycle by FACS analysis, and survival by clonogenic, cell viability, and MTT assays.

Results: HPV16 transformed cell lines exhibited decreased E6 and E7 expression after treatment with Cidofovir. This treatment also increased p53 and Rb as well as MDM2, and p21(WAF1) in HPV16 transformed cell lines. We demonstrated that the combination of Cidofovir and Cisplatin treatment enhanced chemosensitivity in HPV16 transformed cell lines, but the effect in HPV negative tumor cells was less pronounced.

Conclusion: Our results suggest that Cidofovir may have a role in senisitizing HPV16 naturally transformed HNSCC to conventional treatment and could reduce unwanted toxicity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2720. doi:10.1158/1538-7445.AM2011-2720
Abstract 2721: Comparative responses of HPV-positive vs HPV-negative head and neck cancer cells to radiation and/or chemotherapeutic drugs
Authors: Kimple Randall J. , Yang Robert Z. , Armstrong Eric A. , Lambert Paul F. , Harari Paul M.
Published: June 2012

Purpose: HPV is associated with a growing proportion of head and neck squamous cell carcinomas (HNSCCs), which show improved clinical outcome compared with non-HPV associated HNSCC. Whether this improved outcome reflects enhanced responsiveness to radiation and/or chemotherapy remains unclear. There is little data available regarding the radio- and chemo-sensitivity of HPV-associated HNSCC. We provide detailed analysis of radiation response profiles in verified HPV-positive HNSCC lines.

Methods: Degenerate PCR and Southern blot were used to confirm HPV status in HNSCC human tumor cell lines. Clonogenic survival assays were used to assess radiation sensitivity. Proliferation assays were used to assess sensitivity to chemotherapy. Western blot was used to assess EGFR expression, activity, and the effect of EGFR inhibitor treatment.

Results: Clonal expansion of existing HPV-positive HNSCC cell lines was performed to confirm the presence of a homogeneous population of cells and HPV-integration status confirmed by Southern Blot. HPV-positive cells were more sensitive to radiation-induced cell death compared to HPV-negative cells using single dose and fractionated radiation exposure regimens. Of the HPV+ cells tested to date, we have seen further radiosensitization with exposure to EGFR inhibitors (e.g., enhancement ratio 1.27 for UM-SCC47 with erlotinib) despite similar response to the EGFR inhibitor alone. HPV+ tumor xenografts have been raised in immunocompromised mice for in vivo radiation and chemotherapy response assessment.

Conclusions: Consistent with clinical reports, HPV-associated HNSCC cells exhibit increased sensitivity to radiation. The in vitro sensitivity of HPV-positive HNSCC to chemotherapy is in progress, as is the response evaluation of HPV+ xenografts to radiation and chemotherapy. Underlying molecular mechanisms for altered response profiles in HPV+ HNSCC are considered as they pertain to future clinical trial designs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2721. doi:10.1158/1538-7445.AM2011-2721
Abstract 273: Protein kinase C-iota self regulates its expression by regulating the activity of the transcription factor Elk-1
Authors: Pillai Prajit Pillai P. , Acevedo-Duncan Mildred
Published: June 2012

Protein kinase C-iota (PKC-ι), a member of the atypical PKC family of Ser/Thr kinases has been recognized as an oncogene. PKC-ι manifests its effect by targeting various aspects of cancer cells such as growth, invasion and survival. Bcr-Abl has been shown to regulate the activation of the transcription factor ELK-1 which in turn regulates the expression of PKC-ι. Alternatively, we hypothesize that PKC-ι self regulates its expression by directly regulating the activity of ELK-1. Our preliminary data from immunoprecipitation studies show that PKC-ι directly associates with Elk-1 in neuroblastoma and glioma cells. PKC-ι directly phosphorylated cytoplasmic Elk-1 at Ser 383 in these cells. It has been reported that phosphorylation of cytoplasmic Elk-1 at Ser 383 results in conformational change that promotes the nuclear translocation of Elk-1, increased DNA binding and upregulation of its transcriptional activity. Furthermore, our data from cell cycle analysis showed that the nuclear translocation of Elk-1 coincided with the phosphorylation of cytoplasmic Elk-1 by PKC-ι. Robust phosphorylation of cytoplasmic Elk-1 was observed in the G1/S cell cycle phases, however, as the cells entered the M-phase, no phosphorylation of ELK-1 was observed. Similarly, the cytoplasmic to nuclear ratio of Elk-1 decreased as the cells entered the M-phase suggesting the role of PKC-ι in the promoting the nuclear translocation of Elk-1. Thus, our data supports our hypothesis that PKC-ι self regulates its expression by regulating the transcriptional activity of Elk-1.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 273. doi:10.1158/1538-7445.AM2011-273
Abstract 274: PGC-1α over-expression is related to increased cell proliferation and tumorigenesis
Authors: Park Joo-In , Shin Sung-Won , Park Eun-Seon , Yun Seong-Hoon , Lee Seon-A , Jeong Jin-Sook , Kwak Jong-Young
Published: June 2012

Peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) is a coactivator interacting with multiple transcription factors and regulates several metabolic processes. Recent studies have focused on the role of several coactivators in cancer. Especially, a role of PGC-1α in cancer has been controversial. Some studies show that the expression level of PGC-1α decreased in certain cancer tissues and PGC-1α over-expression induces apoptosis in ovarian cancer cells. On the contrary, it has been found that PGC-1α promotes cell growth in prostate cancer cells, suggesting that PGC-1α may be involved in the pathogenesis of cancer. However, the molecular mechanism for it has not been clarified. Thus, the role of PGC-1α in the cell proliferation and tumorigenesis was evaluated using human embryonic kidney HEK293 cells that stably over-expressed PGC-1α. Forced expression of PGC-1α in HEK293 cells resulted in increased cell proliferation and anchorage-independent growth in soft agar. In addition, HEK293 cells that highly expressed PGC-1α enhanced tumor formation when these cells are subcutaneously injected into the bilateral flanks of immunodeficient Balb/c mice. To find out the molecular targets for increased proliferation and tumorigenesis by PGC-1α, GeneFishing DEG screening system was employed. As a result, one up-regulated gene (acyl-CoA binding protein; ACBP) was identified. Up-regulated ACBP expression was confirmed by Western blot and immunofluorescence microscopy. The expression of ACBP was decreased by PGC-1α siRNA transfection. These data suggest that the expression of ACBP may be related to the expression of PGC-1α. In addition, down-regulation of ACBP and PGC-1α by siRNA transfections resulted in the decreased cell proliferation. Taken together, these findings suggest that PGC-1α may promote cell proliferation and tumorigenesis. Thus, PGC-1α can be a good candidate for a molecular therapeutic target for cancers. However, the detailed molecular mechanisms for up-regulation of ACBP by PGC-1α are remained unresolved. Thus, further studies on the clarification of molecular interactions of ACBP and PGC-1α are needed.

This study was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) through the Medical Research Center for Cancer Molecular Therapy at Dong-A University (R13-2002-044-05002-0).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 274. doi:10.1158/1538-7445.AM2011-274
Abstract 2759: Association between genetic variations in DNA damage response pathways and risk for gene methylation in sputum from smokers
Authors: Leng Shuguang , Stidley Christine A. , Willink Randall P. , Liu Yushi , Picchi Maria A. , Berg David Van Den , Gilliland Frank D. , Crowell Richard E. , Belinsky Steven A.
Published: June 2012

The detection of gene promoter hypermethylation in sputum containing exfoliated epithelial cells is a promising biomarker for detecting early incident lung cancer. Therefore, identifying factors that influence the propensity for this epigenetic process throughout the respiratory epithelium is a high priority. The genes and the pathways they modulate underlying the inter-individual susceptibility to DNA methylation remain largely elusive. Accumulating evidence from our group and others implicate DNA damage as an important step in the acquisition of de novo methylation. We hypothesized that genetic variations in genes (n=66) involved in carcinogen metabolism and DNA damage response, including DNA damage repair, cell cycle control, apoptosis, and methylation related pathways will be associated with gene methylation in sputum from lung-cancer free smokers. Three databases including HapMap Stage I database, University of Southern California DNA repair and Children Pulmonary Function Development Oligo Pool Assay (OPA) database, and NIBC dbSNPs database were used to select a comprehensive set of SNPs (OPA1, n=1536) to capture the major genetic variations in these genes. A pilot study for testing the association between these SNPs and risk for methylation was conducted in a subset of people (n=261) selected from Lovelace Smokers Cohort (LSR) based on their methylation index (8-gene panel). Two gene-based analyses were conducted to rank the genes and 683 tagging SNPs from the top 42 genes were selected based on the OPA1 and the HapMap Stage II databases and genotyped in all people (n=1177) with methylation data (12-gene panel) in baseline sputum samples in LSR. The effect of SNPs was tested under an additive inheritance model. A reproducible association was identified in SNPs from the TP53, GSTP1, LIG1, CASP8, BOK, and PMAIP1 genes between the pilot study and the entire study. Ongoing functional studies reveled an association between genotype and expression of LIG1 in bronchial epithelial cells from smokers. This study identified six genes involved in carcinogen detoxification and DNA damage response that were associated with risk for gene methylation in sputum from smokers. (Supported from National Cancer Institute R01 CA097356 and the State of New Mexico as a direct appropriation from the Tobacco Settlement Fund)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2759. doi:10.1158/1538-7445.AM2011-2759
Abstract 276: Role of AP1 elements and TCL1 protein in regulation of the gene encoding PTPROt (protein tyrosine phosphatase receptor-type O) in chronic lymphocytic leukemia
Authors: Motiwala Tasneem , Datta Jharna , Kutay Huban , Roy Satavisha , Checovich Allyn , Zanesi Nicola , Kaou Mohamed , Johnson Amy , Hagan John , Byrd John C. , Croce Carlo M. , Jacob Samson T.
Published: June 2012

The gene for protein tyrosine phosphatase receptor-type O encodes two functional isoforms in a tissue-specific manner. The full-length form is expressed in epithelial cells, particularly in the brain and kidney, whereas the truncated form (PTPROt) is primarily expressed in hematopoietic cells. We have previously demonstrated that PTPROt is a bona fide tumor suppressor (J Biol Chem. 2009 Jan 2;284(1):455-64) and is down-regulated in primary CLL samples (Clin Cancer Res. 2007 Jun 1;13(11):3174-81). Further, studies from two laboratories including ours have shown that Syk and Lyn, two key protein tyrosine kinases involved in B-cell receptor signaling, are substrates of PTPROt, igniting interest in understanding deregulation of this tyrosine phosphatase in CLL. While the PTPRO promoter is methylated, the mechanism of its silencing in the pathogenesis of CLL is unexplored. Here, we utilized the Tcl1 transgenic (Tg) mouse model of CLL and a cell line with TPA-inducible expression of PTPROt to elucidate the mechanism of PTPROt silencing. This study demonstrates that PTPROt is transcriptionally silenced in CD19+ spleen B cells from Tcl1 transgenic (Tg) mouse when compared to wild type mice. As observed with primary human CLL, the methylation of PTPRO CGI (CpG island) is significantly higher in Tcl1 Tg CLL B-lymphocytes than in normal B lymphocytes. Significant suppression of PTPROt is also observed at very early time-point (∼7 wks) in CD19+ spleen B-cells from Tcl1 Tg mice compared to normal spleen B-lymphocytes from age-matched WT mice in the absence of detectable methylation at CGI. This data suggests that transcriptional silencing occurs prior to methylation. To understand further the potential transcriptional mechanism of PTPROt suppression in CLL, the role of AP1 in the expression of this gene was explored. We first demonstrate that AP-1 activation by TPA in U937 cells induces PTPROt expression with concurrent recruitment of c-fos and c-jun to its promoter. PTPROt promoter is also responsive to over- and under-expression of AP-1 confirming the role of AP-1 in PTPROt expression. Next, we demonstrate that Tcl1 can repress PTPROt promoter by altering c-fos expression and c-jun activation state. These findings further substantiate the importance of TCL1 in the pathogenesis of CLL.

[Supported, in part, by grants CA101956 and CA086978].

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 276. doi:10.1158/1538-7445.AM2011-276