bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2101: PMEPA1 co-operates with the androgen responsive gene, NEDD4-1, to control the androgen receptor levels in human prostate cancer cells
Authors: Li Hua , Chijioke Juliet , Sharad Shashwat , Dobi Albert , Srivastava Shiv
Published: July 2012

Androgen receptor (AR) is a male hormone receptor and a nuclear transcriptional factor that plays central role in the differentiation and growth of the prostate gland and alterations of the AR network contribute to prostate tumorigenesis. The stability of the AR protein has been known to be regulated by the MDM2 E3 ubiquitin ligase. Recent investigations from our group suggest the role of PMEPA1-NEDD4-1 negative feedback loop in the regulation of AR protein levels in prostate cancer cells. In the PMEPA1-NEDD4-1 feedback loop, AR transcriptionally activates PMEPA1, which in turn provides a docking platform to recruit NEDD4-1 E3 ubiquitin ligase, to facilitate the proteasome dependent degradation of the AR. We hypothesize that decreased or absent PMPEA1 expression observed in more than 65% for prostate tumors may lead to the gain of AR functions which contribute to prostate tumorigenesis. Here we further investigate how PMEPA1 recruits NEDD4-1 to alter AR protein levels and AR signaling in prostate cancer cells.

Androgen receptor positive prostate cancer cells lines, LNCaP and VCaP, were treated with synthetic androgen R1881 for 24 hours. The androgen receptor, PMEPA1 and NEDD4-1 were knocked down with specific small interfering RNA (siRNA) molecules. Wild-type AR and mt AR (T877A) were ectopically expressed in LNCaP cells with adenoviral expression vectors. Protein levels of AR, PMEPA1, NEDD4-1, as well as AR responsive gene PSA were assessed by immunoblot assays.

Our new observations revealed that that NEDD4-1 was androgen inducible in both LNCaP and VCaP cells. Over-expression of wild-type and mutant AR (T877A) resulted in the upregulation of NEDD4-1 in LNCaP cells. Consistent with these findings, inhibition of AR by siRNA lead to down-regulation of NEDD4-1. As expected, loss of PMEPA1 in LNCaP cells induced up-regulation of AR and NEDD4-1 in an androgen dose-dependent manner. Knockdown of NEDD4-1, rather than NEDD4-2, resulted in elevation of androgen receptor levels and decreases of PMEPA1 expression in LNCaP cells.

Our data suggest that NEDD4-1 is an androgen inducible gene and a complex inter-relationship between PMEPA1, NEDD4-1 and AR. Intriguingly, the AR degradation function of NEDD4-1 depends on the availability of PMEPA1. Thus PMEPA1-NEDD4-1 co-operation is critical for the regulation of androgen receptor protein levels. In conclusion, loss of PMEPA1 in human prostate cancer may also lead to the activation of NEDD4-1 through elevated AR signaling, representing a feed-forward event in tumorigenesis.

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 2101. doi:10.1158/1538-7445.AM2011-2101
Abstract 2102: The germline nonsense variant K1019X results in loss of tumor suppressing function of EphB2 in prostate cancer cells
Authors: Salhia Bodour , Hussain Khateeb Hyder , Carpten John
Published: July 2012

Prostate cancer (PC) is the most common form of cancer in all men and also the second leading cause of cancer related deaths. On average, African American (AA) males are twice as likely to develop prostate cancer and three times more likely to die from it compared with Caucasian men. Previously we combined nonsense-mediated RNA decay microarrays and array-based comparative genomic hybridization for the genome-wide identification of genes with biallelic inactivation involving nonsense mutations and loss of the wild-type allele (Huusko et al, Nature Genetics 2004). This approach enabled us to identify previously unknown mutations in the receptor tyrosine kinase gene EphB2 in ∼7% of prostate tumors. EPHB2 is a member of the tyrosine kinase receptor family of proteins and regulates intracellular signaling pathways involved in cell growth, migration, adhesion, and polarity. Furthermore, there is also strong evidence for EphB2 as a tumor suppressor in colorectal cancer. There are two main isoforms (1 and 2) of the EphB2 gene, which is the result of alternative splicing. Previous studies from our lab also shows that a germline 3055A>T nonsense variant (K1019X) in the EphB2 gene differs in frequency between AA and Caucasian males, is associated with increased risk for PC in AA men with a positive family history, and may be an important genetic risk factor for prostate cancer in AA. The DU145 prostate cancer cell line, originating from a brain metastasis, carries a truncating mutation of isoform 1 of EphB2 and a deletion of the remaining allele. Transfection of DU145 cells, which lack functional EPHB2, with wild-type EPHB2 suppresses clonogenic growth. The goal of this project is to determine the effect of the K1019X mutation on the growth of DU145 cells. Introduction of wild-type and 3055A>T EphB2 into DU145 cells using a lentiviral-based vector led to successful expression as seen by RT-PCR and western blot analysis. We also demonstrated using RT-PCR and western blot analysis that while DU145 cells lack functional expression of the isoform 1, there is expression of the second isoform, implying that the tumor suppressing function of EPHB2 may be unique to isoform 1. Using a sulforhodamine B assay we demonstrated that the K1019X mutation inhibits growth suppression of DU145 cells as compared with wild-type EPHB2. These initial findings suggest that the K1019X is a true functional variant and support the role of the K1019X in increasing prostate cancer risk in AA.

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 2102. doi:10.1158/1538-7445.AM2011-2102
Abstract 2107: Downregulation of ASPP2 in choriocarcinoma contributes to increased migratory potential through Src activation
Authors: Mak Victor CY , Lee Lee , Siu Michelle KY , Wong Oscar GW , Lu Xin , Ngan Hextan YS , Wong Esther , Cheung Annie NY
Published: July 2012

Gestational choriocarcinoma is a malignant tumour derived from placental trophoblast and is the most aggressive member of gestational trophoblastic disease (GTD). Apoptotic stimulating protein of p53-2 (ASPP2) is a tumor suppressor member of the ASPP family which transactivates p53-dependent apoptotic pathway. In this study, we examined the expression profile of ASPP2 in choriocarcinoma in comparison with normal placentas and hydatidiform moles which is a type of GTD that carries malignant potential. Results from quantitative PCR and immunohistochemical studies showed that downregulation of ASPP2 was detected in choriocarcinoma at both RNA and protein levels. ASPP2-transfected choriocarcinoma cells (namely JEG-3 and JAR) showed an increase in apoptosis and a decrease in cell migration as detected by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and wound healing assays respectively, illustrating the complex action of ASPP2 on cell functions other than program cell death. Transfection of ASPP2 but not ASPP1, another tumor suppressive member of the ASPP family, decreased Src-pY416 phosphorylation, suggesting an inactivating effect of ASPP2 on Src. Moreover, this ASPP2-induced inactivation of Src could be abolished by RNA interference using Csk small interfering RNA (siRNA). All these findings suggested that the ability of ASPP2 to attenuate Src activation was specific to ASPP2 in a Csk dependent manner. Taken together, we demonstrated a loss of tumor suppressive ASPP2 in choriocarcinoma with effects on cell migration as well as apoptosis. We also unveiled a possible mechanistic link between ASPP2 and Csk/Src signaling pathway, implicating the multiple cellular functions of ASPP2.

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 2107. doi:10.1158/1538-7445.AM2011-2107
Abstract 2120: Secreted protein acidic and rich in cysteine, like 1(SPARCL1), inhibits aggressiveness and relates to better prognosis in colorectal cancers
Authors: Zhang Hang , Hu Hanguang , Ge Weiting , Liu Xiyong , Chen Huarong , Yu Shujing , Zhang Suzhan , Yen Yun , Zheng Shu
Published: July 2012

Secreted protein that's acidic and rich in cysteine, like 1(SPARCL1), an extracellular de-adhesion glycoprotein, was down-regulated in several solid cancers such as non-small cell lung cancer and pancreatic cancer. Our previous study revealed that expression of SPARCL1 was negatively related to liver metastasis of colorectal cancer (CRC). To clarify the function of SPARCL1 and its mechanism in CRC, the overexpression cell clone, RKO-SPARCL1, was created for illustrating biological behavior of SPARCL1 in vitro and in vivo. It was shown that SPARCL1 significantly reduced colony formation (p=0.027), invasion ability (p=0.001) and adhesion (p=0.04) of CRC cells in vitro. In comparison with vector control (RKO-pLXSN), RKO-SPARCL1 displayed significantly reduction in liver metastatic nodules in intrasplenic injection nude mice model (p=0.009). Meanwhile, tissue samples from 412 CRC patients were reassembled as tissue microarray for an outcome study. The antibody against SPARCL1 was developed for Immunohistochemistry (IHC) staining to assess the expression level of SPARCL1. Uni- and multivariate Logistic analysis demonstrated that SPARCL1 was negatively related with poorly tumor differentiation (p=0.001), lymph node metastasis (Odds ratio, OR=0.67, 95% 0.45-1.00) and distant metastasis (OR=0.39, 95% 0.18-0.82). The Kaplan-Meier analysis revealed that overexpression of SPARCL1 was significantly related to better overall survival in CRCs (p=0.004). Furthermore, the multivariate COX proportional hazard analysis demonstrated that SPARCL1 significantly reduced the risk of death from CRC (Hazard ratio, HR=0.57, 95% 0.39-0.84). Based on bioinformatics gene ontology analysis for gene expression microarray, overexpression of SPARCL1 significantly inhibited focal adhesion pathway and other tumor-associated oncogenes, such as S100A4 and ERBB3, in RKO cell line. Therefore, it is concluded that SPARCL1 may function as a tumor suppressor inhibiting the aggressiveness of cancer cells and reducing the risk of death from CRCs. It is suggested that SPARCL1 may serve as a prognostic biomarker for CRCs.

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 2120. doi:10.1158/1538-7445.AM2011-2120
Abstract 2124: Comprehensive analysis of hormone receptor status during prostate cancer progression: A novel prognostic role for pAR and ERbeta
Authors: Ruiz Christian , Zlobec Inti , Stuerm Susanna , Rey Silvia , Schneider Sandra , Oeggerli Martin , Gasser Thomas , Zellweger Tobias , Bachmann Alexander , Bubendorf Lukas
Published: July 2012

Aims: Patients with advanced prostate cancer (PrCa) are usually treated with androgen withdrawal. Although this therapy is effective at the beginning, nearly all prostate cancers become refractory to it. Hormone receptors play a crucial role during this progression. Aim of this study was to analyze the genomic and expression status of hormone receptors in prostate cancer and the evolution of these markers in the development of castration-resistance.

Methods: We selected 915 transurethral resection (TURP) specimens from 107 untreated PrCa and from 101 castration-resistant (CR) PrCa. These samples were used for the construction of a tissue microarray (TMA). In addition, we included 56 distant metastases. We analyzed the androgen receptor (AR) gene copy number by fluorescence in-situ hybridization and the expression profiles of AR, phosphorylated AR (pAR), ERβ, ERα and the proliferation marker Ki67 by immunohistochemistry.

Results: AR gene amplification was almost restricted to PrCa and was significantly associated with increased AR protein expression (p<0.0001) and higher tumor cell proliferation (p=0.001). Interestingly, although pAR was predominantly found in the CR PrCa (p=0.003), pAR expression in untreated PrCa patients identified a subgroup of patients with poor survival (p<0.05). In contrast to ERα expression, which was restricted to CR PrCA cells (10%), ERβ was found in 40% of the PrCa, independent of treatment status. Similar to pAR, the presence of ERβ in untreated patients was significantly associated with adverse prognosis (p<0.005).

Conclusions: This is the first comprehensive study comparing the hormonal receptor status in a large cohort of hormone-naïve and CR PrCa. Our results strongly suggest a major role for pAR and ERβ in untreated PrCa. Expression of these markers might be a mechanism of CR tumor growth.

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 2124. doi:10.1158/1538-7445.AM2011-2124
Abstract 2125: Circadian crosstalk modulation of estrogen receptor alpha promoter activity
Authors: Villa Linda M. , Cousins Sarah , Capelluto Daniel G.S. , Finkielstein Carla V.
Published: July 2012

The proper timing of cell division is a major factor contributing to the regulation of normal growth and emerges as a fundamental process in the development of most cancers. The existence in most, if not all, living organisms of many behavioral and physiological events that occur at well-defined and controlled times argues for the presence of time-keeping systems that allow them to adapt to cyclic changes in environmental conditions. Disruption of circadian rhythm has recently emerged as a new potential risk factor in the development of cancer, pointing to the core gene period 2 (per2) as a tumor suppressor. Circadian disruption has been epidemiologically linked to a raising number of estrogen dependent tumors identified in night-shift workers. In the present study, we investigate the signaling molecules that modulate the circadian expression of estrogen receptor alpha (ERa). ERa mRNA oscillates in a 24 h period and, unlike the circadian factor Per2, ERa peaks during the light phase of the day. Because up regulation of ER relates to tumor development, defining the mechanisms of ERa expression will contribute to our comprehension of cellular proliferation and regulation of normal developmental processes. Transcriptional activation of ERa was measured using a reporter system in Chinese Hamster Ovary and MCF-7 cell lines. Data show that Per2 influence ERa transcription through a non-canonical mechanism independent of its circadian counterparts. Promoter analysis using the Alibaba 2.0 suite revealed the presence of various putative novel partners. Among them, OCT-1 was found to directly interact with Per2 and with corresponding response element within the ERa promoter bit in vitro and endogenously in CHO and MCF-7 cells. The predicted binding site of OCT-1 is 867 bps downstream of the promoter. Pull-down assays were used to map direct interaction of various Per2 recombinant proteins and the DNA-binding domain of OCT-1. Radiolabeled OCT-1 was found to bind to the C-terminal end of Per2. Electrophoretic mobility shift assays were used to determine direct binding of OCT-1 to the promoter and chromatine immunoprecipitation validate the interactions in cells. Fluorescence anisotropy and surface plasmon resonance were employed to establish the binding affinity of OCT-1 to the ERa promoter and Per2. OCT-1 was found to have a high affinity for the ERa promoter (∼10 nM). Overall, our data points towards a direct regulation of estrogen receptor signaling by circadian modulators.

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 2125. doi:10.1158/1538-7445.AM2011-2125
Abstract 2127: The role of FOXD3 in resistance to PLX4032/4720-induced cell death in mutant B-RAF melanoma cells
Authors: Basile Kevin J. , Abel Ethan V. , Aplin Andrew E.
Published: July 2012

Melanoma cells driven by mutant B-RAF are highly resistant to chemotherapeutic treatment. Recent phase I results with PLX4032/RG7204, which selectively inhibits BRAF/MEK/ERK1/2 signaling in mutant B-RAF cells, has given encouragement to this struggling field. Despite initial tumor shrinkage, most responders in the trial experienced tumor relapse over time. Furthermore, 19% of patients failed to show any significant tumor regression. These findings indicate that both intrinsic and acquired resistance will hamper the clinical efficacy of PLX4032. We have previously shown that the stemness factor, FOXD3, is up-regulated following inhibition of mutant B-RAF-MEK signaling in mutant B-RAF melanoma cells. Here, we show that up-regulation of FOXD3 after PLX4032 and PLX4720 (the non-clinical tool compound for PLX4032) treatment confers resistance to cell death. siRNA-mediated knockdown of FOXD3 significantly enhanced the cell death response after PLX4032/4720 treatment in mutant B-RAF melanoma cell lines. Additionally, up-regulation of FOXD3 after PLX4720 treatment was attenuated in non-adherent conditions and correlated with enhanced cell death. Ectopic expression of FOXD3 in non-adherent cells significantly reduced cell death in response to PLX4720 treatment. Together, these data indicate that up-regulation of FOXD3 is an adaptive response to B-RAF inhibitors that promotes a state of drug resistance.

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 2127. doi:10.1158/1538-7445.AM2011-2127
Abstract 2130: Overcoming chemotherapy resistance by targeting LDHA mediated glycolysis
Authors: Liu Zixing , Zhou Ming , Zhao Yuhua , Yan Ding , Liu Hao , Tan Ming
Published: July 2012

Taxol is one of the most effective chemotherapeutic agents for the treatment of patients with breast cancer. Despite impressive clinical responses initially, the majority of patients eventually develop resistance to Taxol. Lactate dehydrogenase-A (LDH-A) is one of the predominant isoforms of LDH expressed in breast tissue, which controls the conversion of pyruvate to lactate and plays an important role in glucose metabolism. In this study we investigated the role of LDH-A in mediating Taxol resistance in human breast cancer cells. Taxol-resistant subclones, derived from the cancer cell line MDA-MB-435, sustained continuous growth in high concentrations of Taxol while the Taxol-sensitive cells could not. The increased expression and activity of LDH-A were detected in Taxol-resistant cells when compared with their parental cells. The downregulation of LDH-A by siRNA significantly increased the sensitivity of Taxol-resistant cells to Taxol. A higher sensitivity to the specific LDH inhibitor, oxamate, was found in the Taxol-resistant cells. Furthermore, treating cells with the combination of Taxol and oxamate showed a synergistical inhibitory effect on Taxol-resistant breast cancer cells by promoting apoptosis in these cells. LDH-A plays an important role in Taxol resistance and inhibition of LDH-A re-sensitizes Taxol-resistant cells to Taxol. This supports that Warburg effect is a property of Taxol resistant cancer cells and may play an important role in the development of Taxol resistance. To our knowledge, this is the first report showing that the increased expression of LDH-A plays an important role in Taxol resistance of human breast cancer cells. This study provides valuable information for the future development and use of targeted therapies, such as oxamate, for the treatment of patients with Taxol-resistant 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 2130. doi:10.1158/1538-7445.AM2011-2130
Abstract 2136: Expression of fusion proteins in acute myeloid leukemia cells increases sensitivity to histone deacetylase inhibitors
Authors: Petruccelli Luca A. , Rice Kim L. , Pettersson Filippa , Nichol Jessica N. , Skoulikas Sophia , Licht Jonathan D. , Miller Wilson H.
Published: July 2012

Acute myeloid leukemias (AMLs) are often characterized by chromosomal translocations resulting in the expression of fusion proteins (FP). Some FP have been demonstrated to recruit histone deacetylases (HDACs) and repress the expression of DNA repair genes. This may result in an increased sensitivity to histone deacetylase inhibitors (HDI) due to their ability to also down-regulate DNA repair gene expression and induce DNA damage. We have tested the sensitivity of PLZF-RARα, PML-RARα and AML1-ETO inducible cell lines to HDI in order to characterize changes in the mechanisms of cell death.

Treatment of U937 cells with vorinostat results in DNA damage as measured by the COMET assay, followed by cell death. To test the effect of FP expression, U937 cells stably transfected with PLZF-RARα, PML-RARα or AML1-ETO cDNA under the control of a tetracycline-off or a zinc-inducible system were treated with vorinostat and assayed for cell death in the presence/absence of FP. FP expression resulted in increased cell death and caspase-3/7 activation. This effect was found to be largely caspase driven as pre-treatment with the pan-caspase inhibitor Z-VAD-FMK resulted in protection against vorinostat-induced cell death. In addition, FP expressing cells were also exposed to the DNA-targeting agents Doxorubicin, Etoposide, Cisplatin and ionizing radiation. Again, FP expression resulted in increased cell death.

In addition, we investigated the effect of FP expression on vorinostat sensitivity using a PLZF-RARα murine hematopoietic model. A retroviral expression system was used to overexpress PLZF-RARα in lineage-depleted (Lin-) murine hematopoietic progenitors, followed by vorinostat treatment in the absence/presence of PLZF-RARα. The increased sensitivity of FP expressing cells to HDI and DNA-targeting agents suggests a mechanism where the combination of an FP expression and HDI results in an increased accumulation of DNA damage, leading to enhanced cell death.

These findings are significant as they point to FP expressing AMLs as a target group that may respond better to HDI-based 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 2136. doi:10.1158/1538-7445.AM2011-2136
Abstract 391: Inflammatory mediators of prostate cancer metastasis
Authors: Martinez-Ferrer Magaly , Qi Ying , Sanchez Maria M. , Bhowmick Neil A.
Published: July 2012

Inflammation has been linked to the initiation and metastatic progression of prostate cancer. We previously reported results showing that CX3CL1 and IL-15 were predominantly down-regulated in prostate cancer patients that develop biochemical recurrence following prostatectomy. This study tests the hypothesis that chemokine biomarkers that predict biochemical recurrence of prostate cancer regulate metastatic progression of the cancer. In order to determine the function of the chemokines, PC3 and LNCaP prostate cancer cell lines were used alone and in combination with conditioned media from prostate stromal cells expressing the chemokines of interest. IL-15 and CX3CL1 cDNAs were subcloned into lentiviral constructs. The lentiviral constructs were transduced into prostate stromal cells developed from wild type C57BL/6 mice. Seventy-two hours conditioned media was used to verify the expression of the respective chemokines by ELISA. The individual prostate cancer cell lines (PC3 and LNCaP) were incubated in the respective stromal conditioned media and characterized for measurable characteristics that promote a cancer cell to be metastatic. In this study we show that IL-15 and CX3CL1 significantly decreased (P<0.0001) PC3 proliferation in vitro. Furthermore, IL-15 and CX3CL1 also had the ability to significantly inhibit migration of PC3 prostate cancer cells in vitro (P<0.01). Introducing IL-15 and CX3CL1 into the stromal microenvironment of the androgent independent PC3 cells significantly increased apoptosis (P<0.05). No significant changes were observed in the androgen dependent LNCaP prostate cancer cells. Our results indicate that IL-15 and CX3CL1 may suppress metastasis in vitro by decreasing proliferation and migration, and increasing apoptosis in the highly metastatic PC3 prostate cancer cell line. The studies will help to enable the dissection of the role of the chemokines on cancer cells in the context of its stromal micronvironment.

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 391. doi:10.1158/1538-7445.AM2011-391
Abstract 4069: 2-deoxyglucose and compound C reversed acidification but enhanced growth inhibition in colon cancer cells treated with metformin and phenformin
Authors: Lea Michael A. , Chako Jerel , Bolikal Sandhya , Hong Ji-Young , Chung Ryan , Ortega Andres , desBordes Charles
Published: July 2012

A report that effects of butyrate on some cells may be mediated by activation of AMP-dependent kinase (AMPK) prompted us to examine if other AMPK activators can induce differentiation and inhibit proliferation of colon cancer cells in a manner similar to butyrate. Using induction of alkaline phosphatase as a marker, we observed that compound C, an AMPK inhibitor, could decrease the differentiating effect of butyrate or valproate on SW1116 and Caco-2 colon cancer cells. On the other hand, A769662, an activator of AMPK did not increase alkaline phosphatase activity and decreased the induction seen with butyrate. Metformin was observed to be less effective than butyrate in the induction of alkaline phosphatase but was more effective as a growth inhibitor. Phenformin was found to be a more potent growth inhibitor than metformin and both compounds cause acidification of the medium when incubated with colon cancer cells. pH changes were monitored with a pH electrode and by the decrease in absorbance of phenol red at 560 nm. Coincubation with compound C decreased the acidification caused by the biguanides. Combined incubation of 2-deoxyglucose with either of the biguanides prevented the acidification of the medium but enhanced the growth inhibitory effects. Growth inhibitory effects of biguanides appeared less with a tetrazolium reduction assay than with thymidine incorporation but supported the conclusion that combination with 2-deoxyglucose could increase growth inhibition caused by biguanides.

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 4069. doi:10.1158/1538-7445.AM2011-4069
Abstract 4097: Sorafenib sensitizes solid tumors to TRAIL or TRAIL receptor agonist antibodies
Authors: Abdulghani Junaid , Allen Joshua E. , Dicker David T. , Smith Charles D. , Humphreys Robin C. , El-Deiry Wafik S.
Published: July 2012

Solid carcinomas display considerable resistance to chemotherapeutic drugs and tumor cell apoptosis-inducing agents such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cell death. A phase III clinical trial with the multi-kinase inhibitor sorafenib (Nexavar) in Hepatoceullular carcinoma (HCC) was completed leading to the first FDA-approved drug therapy for liver cancer in 2007. Phase I/II trials have been completed with a fully-human anti-TRAIL death receptor 1 (DR4) agonist antibody (mapatumumab) in non small-cell lung carcinoma and non-Hodgkin's lymphoma and phase I trials with an anti-TRAIL-R2 (DR5) monoclonal antibody (lexatumumab) in advanced cancers. We hypothesized that sorafenib and TRAIL or sorafenib and TRAIL receptor agonist antibodies (mapatumumab or lexatumumab) may overcome resistance to apoptosis in a panel of TRAIL-resistant solid carcinoma cell lines. We observed that sorafenib induces apoptosis of HepG2 and Hep3B cells in a dose-dependent manner. In addition, sorafenib is a potent sensitizer of HCC cell lines to TRAIL. We have also found that single agent lexatumumab causes cell death in HepG2, Hep3B and SNU449 cells whereas mapatumumab does not. The combination of sorafenib with TRAIL or either TRAIL receptor agonist antibody enhances apoptosis in HCC cell lines. We found that in other solid tumor types including prostate, breast and colon cancer there is a synergistic interaction between sorafenib and TRAIL or TRAIL receptor agonist antibodies. Furthermore, these combinations prevent the growth of tumors in vivo. Sorafenib downregulates the expression of Mcl-1 protein, a member of the Bcl-2 family that has been previously found to be overexpressed in about 50% of HCC patient samples. Sorafenib was also found to inhibit Stat3 activation by Jak2 kinases. These findings suggest a molecular rationale for combining these agents in therapy of solid tumors in clinical trials.

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 4097. doi:10.1158/1538-7445.AM2011-4097
Abstract 411: Absence of leukotriene B4 receptor-1 promotes colon tumorigenesis in the ApcMin/+ mice by modulating gut microbiota
Authors: Jala Venkatakrishna R. , Maturu Paramahamsa , Krishnan Elangovan , Mathis Steven P. , Subbbarao Krishnaprasad , Bodduluri Sobha R. , Wang Min , Jenson Alfred B. , Proctor Mary L. , Bodduluri Haribabu
Published: July 2012

Leukotriene B4, a potent lipid mediator of inflammation acts through the G-protein coupled receptor, BLT1. The BLT1-/- mice displayed substantial protection in inflammatory disease models of arthritis, asthma and atherosclerosis. To examine the role of BLT1 in progression of cancers known to be promoted by inflammation, we crossed the BLT1-/- mice onto mice with a heterozygous mutation in the adenomatous polyposis coli (ApcMin/+) gene. The BLT1-/-ApcMin/+ mice demonstrated an increase in the rate of spontaneous intestinal tumor development and accelerated mortality. Unlike ApcMin/+ mice that develop mostly small intestinal tumors the BLT1-/-ApcMin/+ mice developed large colonic adenomas. Tumors from the BLT1-/-ApcMin/+ mice showed increased rates of proliferation, decrease in apoptosis and an increase in the expression of tumor promoting inflammatory markers such as TNF-α and CXCL1 and COX2 when compared to tumors from the ApcMin/+ mice. Microarray analysis of transcriptome showed that the paradoxical increase in inflammation in tumors from the BLT1-/-ApcMin/+ mice is coincidental with defective host response to infections. The expression of angiogenins, a class of antibacterial proteins was significantly reduced in tumors from BLT1-/-ApcMin/+ mice. Further, analysis of gut flora (by 16S ribosomal DNA sequences) identified major differences in microbiome colonizing the BLT1-/-ApcMin/+ and ApcMin/+ mice. BLT1-/-ApcMin/+ mice rederived and raised under germ-free conditions are completely protected from colon cancer development.

To examine the role of Toll-like receptor mediated signaling events involved in tumor promotion in the absence of BLT1, we developed BLT1/MyD88 double deficient mice. The BLT1-/-MyD88-/- mice were highly susceptible to lethal neonatal infections indicating the cooperative interactions between TLR and leukotriene pathways in host response. These BLT1-/-MyD88-/- mice could be rescued by treatment with a broad-spectrum antibiotic. The MyD88-/-ApcMin/+ mice are highly protected from intestinal cancers. The BLT1-/-MyD88-/-ApcMin/+ mice are also highly protected indicating that BLT1-mediated host defense acts upstream of MyD88-mediated tumor promoting inflammation. While both BLT1 and MyD88 are important in host defense only the MyD88 but not BLT1 activated pathways are required to initiate tumor promoting inflammation. These results identify novel roles for gut microbiota in promoting colon cancer and for BLT1 in preventing the colon cancer development by shaping the gut microbiome.

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 411. doi:10.1158/1538-7445.AM2011-411
Abstract 4179: Mitochondrial DNA haplogroup M7b/c associated with the clinical outcome of OSCC in Taiwan
Authors: Hsieh Ling-Ling , Lai Chih-Husiung , Huang Shiang-Fu , Chen I-How , Liao Chun-Ta , Wang Hung-Ming
Published: July 2012

A large volume of studies have indicated that polymorphisms in the mitochondrial genome are associated with risk of various diseases, including cancer. However, only few studies examined the effect of polymorphisms on cancer outcome. To explore the possible role of mitochondrial polymorphisms on clinical outcome of oral squamous cell carcinomas (OSCCs) in Taiwan, whole mitochondrial genome was genotyped by DNA direct sequencing and haplogroup was defined using HaploGrep program in 305 OSCCs. One hundred and sixty-five variant sites with minor allele frequency (MAF) >3 % were found in our study. Among them, 6 variant sites (1 mtLP in HVR2 and 5 SNPs at T204C, C4071T, C4850T, T16311C, T16362C) were associated with overall survival. An index score designated as the total effects of the genotypes of these 6 variant sites on survival for each individual was also developed using the estimates from the Cox model. We found that individual with the higher index score had the poorer disease-free and overall survival. In addition, an association between Asian specific haplogroup M7b/c (containing C4071T variant) and poor overall survival was observed. In conclusion, the findings provide the first evidence pointing toward mitochondrial variants affect the clinical outcome in OSCC.

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 4179. doi:10.1158/1538-7445.AM2011-4179
Abstract 4186: Survival time for patients with glioblastomas is highly correlated with increased expression of major mitotic checkpoint genes
Authors: Bie Li , Xia Xiao-Qin , Qiu Ji-qing , Cheng Pui , Rondeau Gaelle , Zhao Gang , McClelland Michael
Published: July 2012

Glioblastomas are the most common and deadly CNS neoplasms. Survival time correlates with pathological grade; most World Health Organization grade III and grade IV cases die within one year of diagnosis, whereas lower grades sometimes live for years. With the goal of optimizing objective prognostic molecular staging methods for gliomas, we examined three independent microarray datasets with a total of 6 normal, 14 grade I- II, 13 grade III and 13 grade IV gliomas, using a cross-platform analysis suite (http://www.webarraydb.org). We noticed that a number of mitotic spindle assembly checkpoint (SAC) genes had transcript levels significantly altered across different pathological grades. SAC genes ensure that accurate chromosome segregation is maintained during mitosis. Previous studies have shown failure of the mitotic spindle assembly checkpoint (SAC) leads to genomic instability and neoplastic transformation. Several studies of malignant tumor suggested that increased mRNA levels of the mitotic checkpoint correlates with tumor progression, including in breast cancer and bladder cancer. Eight major mitotic spindle checkpoint genes that had significant increases in gene expression levels with increasing glioma grade in the microarray data (p < 0.001, ANOVA) were selected for quantitative reverse transcription PCR (qRT-PCR) analysis in 40 additional glioma tumors and 6 normal brain tissues; BUB1, BUB1B, BUB3, CENPE, MAD1L1, MAD2L1, CDC20, and TTK. One of these genes, CDC20, is already known to be differentially expressed across grades and inclusion allowed the relative performance of other genes to be assessed. In our study, the average mRNA transcript levels for all of these checkpoint genes increased with increasing grade. The correlations with grade had a significance level of p<0.05 (ANOVA) for BUB1, BUB1B, CENPE, MAD1L1 and CDC20. Mutations or epigenetic changes in these five genes have not yet been noted to play a significant role in the causation of chromosomal instability in glioblastomas, nor in most other cancers, an exception being BUB1mutations in some cases of colorectal cancer. The consistently high level of these particular transcripts in aggressive gliomas is perhaps due to compensation for other defects in the cell machinery that would otherwise be catastrophic. Kaplan-Meier analysis showed that BUB1B and CDC20 were independent prognostic indicators for overall survival (p<0.05). Further regression analysis indicated that changes in expression of BUB1B and CDC20, and perhaps CENPE, rival glioma grade as excellent prognosticators of survival.

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 4186. doi:10.1158/1538-7445.AM2011-4186
Abstract 4192: Role of NF-κB regulators A20 and CARD11 in middle eastern diffuse large B cell lymphoma
Authors: Abubaker Jehad , Bavi Prashant , Jehan Zeenath , Al-Haqawi Wael , Sultana Mehar , Belgaumi Sameer M. , Siraj Sarah , Ajarim Dahish , Al-Dayel Fouad , Uddin Shahab , Al-Kuraya Khawla S.
Published: July 2012

Aberrant NF-κB regulation has been observed in many hematopoietic malignancies including diffuse large B cell lymphoma (DLBCL). NF-κB gene plays a role in lymphomagenesis through the transcriptional activation of genes associated with cell proliferation, angiogenesis, metastasis, tumor promotion, inflammation and suppression of apoptosis. CARD11 and A20 genes are known positive and negative regulators of the NF-kB activation pathway and can alternate the NF-kB activity. Considering the potential therapeutic utility of targeting NF-kB and its key modulators, we studied CARD11 genetic alterations (mutations and amplifications), A20 mutations, and immunohistochemical expressions of A20 and CARD11 protein in 150 DLBCL samples. Incidence of CARD11 and A20 mutations was 10.7% and 15.3% of respectively. NF-kB activation was significantly associated with A20 mutation (p=0.0456) thereby highlighting the role of A20 as a tumor suppressor gene and its role in NF-kB inhibition. Interestingly, CARD11 amplification was seen in a significant proportion of the DLBCL (23%) and was linked to NFkB activation (p = 0.0111). A poor overall survival was noted in the DLBCL harboring A20 mutations (p=0.0491) and also in the DLBCL showing presence of CARD11 gene amplification (p=0.0588). Our study highlights the role of CARD11 gene amplifications as a novel mechanism for NF-kB activation and demonstrates clinico-pathological significance of CARD11 and A20 alterations in Middle Eastern DLBCL.

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 4192. doi:10.1158/1538-7445.AM2011-4192
Abstract 4194: Constitutive DNA-damage signaling promotes cancer cell proliferation through Chk1-CIP2A pathway independent of ATM-ATR
Authors: Khanna Anchit , Böckelman Camilla , Schreck Ilona , Weiss Carsten , Visakorpi Tapio , Ristimäki Ari , Westermarck Jukka
Published: July 2012

DNA damage is a hallmark of malignantly transformed cells. Accordingly, overexpression of the DNA damage activated kinases has been observed in different human cancers. However, it is unclear whether constitutive DNA damage present in unperturbed cancer cells promotes tumourigenesis.

Here we show that increased activity of DNA damage sensitive kinase Chk1 promotes proliferation of several cancer cell types by stimulating expression of CIP2A protein. Either chemical or genetic inhibition of Chk1, and not of ATM-ATR, results in potent inhibition of CIP2A protein expression levels. Importantly, Chk1 siRNA-elicited inhibition of cell proliferation and clonogenic growth is rescued by overexpression of CIP2A from a heterologous promoter. Moreover, in clinical (human) tumor samples there is a significant association between CIP2A and Chk1 expression in both ovarian and gastric cancers. Intriguingly, meta-analysis of seventeen published genome wide studies on different types of cancers unveils a striking similarity in the gene expression patterns of both CIP2A and Chk1. Amongst these, 12/17 studies show overexpression (top 10%) of both these proteins. Additionally, similarly to CIP2A, increased Chk1 expression is shown to correlate with tumor progression in human cancer.

In summary, these results identify a novel function for DNA damage kinase Chk1 in regulation of the human oncoprotein CIP2A. In general, these results provide an unprecented molecular mechanism by which constitutive DNA damage present in cancer cells promotes tumourigenesis. Additionally, as CIP2A is not significantly expressed in most of the normal human tissues, it is proposed that targeting of CIP2A might abrogate the Chk1-mediated support of proliferation without concerns related to anticancer therapy directly targeting Chk1.

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 4194. doi:10.1158/1538-7445.AM2011-4194
Abstract 4205: Regulation of Hif-1α expression by NADPH oxidase 5 (Nox5) in human cancer cell lines
Authors: Antony Smitha , Wu Yongzhong , Liu Han , Jiang Guojian , Juhasz Agnes , Lu Jiamo , Roy Krishnendu K. , Doroshow James H.
Published: July 2012

Reactive oxygen species (ROS) produced by NADPH oxidases (Noxs) participate in signaling cascades regulating proliferation. However, the relative contribution to tumor cell growth by the seven Nox homologues (Nox1-5 and Duox 1 and 2) remains unclear. Several studies have proposed that Nox5 plays a role in promoting cell proliferation in Hairy cell leukemia, Barrett's esophageal adenocarcinoma cells, and in prostate cancer; however, little is known about the signaling pathways mediated by Nox5. We explored the functional role of Nox5 in a variety of tumor cell lines, including the NCI-60 cell panel; real time RT-PCR revealed that several melanoma lines express Nox4 and Nox5, but no Nox1 mRNA; and that prostate cell lines express Nox5 mRNA. Of the Nox5- expressing NCI-60 human cancer cell lines, we studied UACC-257 melanoma and PC-3 prostate cancer cells. These lines were characterized for variations in their N-terminus Ca2+ binding domains; RT-PCR revealed that both cell lines expressed the Nox5α and Nox5γ forms. The functional role of Nox5 in UACC-257 and PC-3 cells was studied by generating stable Nox5-overexpressing clones, and by transiently silencing Nox5 that was expressed endogenously, as well as that in clones stably overexpressing Nox5. Redox-sensitive assays for both intra- and extracellular ROS production confirmed that Nox5 was functional and generated superoxide in UACC-257 and PC-3 clones overexpressing Nox5. Nox5 could be activated by the phorbol ester PMA and by the Ca2+ ionophore ionomycin in overexpressing clones. This enzymatic activity was Ca2+- and flavin dehydrogenase-dependent; the calcium chelator BAPTA-AM and the flavoprotein inhibitor DPI (200nM) significantly decreased Nox5-mediated ROS production. Overexpression of Nox5 in UACC-257 cells resulted in increased normoxic Hif-1α expression that was also Ca2+-, flavin dehydrogenase- and ROS-dependent. Silencing Nox5 by RNAi significantly inhibited both endogenous and PMA-stimulated ROS production, confirming that ROS production was Nox5-mediated. Knockdown of both endogenous and overexpressed Nox5 in both UACC-257 and PC-3 cells resulted in decreased Hif-1α expression. Studies to characterize the mechanisms by which Nox5 modulates cell proliferation through the HIF-1α pathway are ongoing. Our experiments suggest that Nox5 expression may play an important role in the generation of high local concentrations of ROS that could contribute to activation of Hif-1α and promote cell proliferation in human cancers.

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 4205. doi:10.1158/1538-7445.AM2011-4205
Abstract 4209: Genotoxic effects of arsenic trioxide-induced oxidative stress in human hepatocellular carcinoma (HepG2) cells
Authors: Brown Erika T. , Yedjou Clement G. , Tchounwou Paul B.
Published: July 2012

Recent studies in our laboratory indicated that oxidative stress plays a key role in arsenic trioxide (ATO)-induced cytotoxicity in human cancer cells. In the present investigation, we used human hepatocellular carcinoma (HepG2) cells as a model to determine whether arsenic induced DNA damage is mediated through oxidative stress. To achieve this goal, oxidative stress biomarkers were measured by lipid peroxidation, glutathione peroxidase, and catalase assays, respectively. The degree of DNA damage was estimated by the means of comet assay. The results of the lipid peroxidation showed a significant increase (p <0.05) of malondialdehyde (MDA) levels with increasing ATO concentrations. Results from the glutathione peroxidase and catalase assays showed a gradual decrease in antioxidant enzyme activity in ATO-treated cells as compared the control. In regard to the comet assay, a significant increase (p < 0.05) in comet tail-length and percentages of DNA cleavage were observed in ATO-treated cells using the comet assay. Taken together, our research demonstrated that oxidative stress modulates ATO mediated DNA damage in HepG2 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 4209. doi:10.1158/1538-7445.AM2011-4209