New Pancreatic Genomics Papers

This weeks batch of papers includes an interesting review of the current treatments available for pancreatic cancer and their biomolecular targets.  We also have a number of papers on microRNA targets and their roles in sensitizing pancreatic cancer tumors to gemcitabine.

The Pharma Strategy blog has a recent article on EGFR and KRAS inhibitors in colorectal cancer.  As you may recall from some of the articles in the Pancreatic Genomics group, EGFR and KRAS are both targets in pancreatic cancer.

  • Thymoquinone: Potential cure for inflammatory disorders and cancer.
    Biochemical pharmacology (2011).Chern Chiuh Woo, Alan Prem Kumar, Gautam Sethi, Kwong Huat Benny Tan et al.Thymoquinone is an active ingredient isolated from Nigella sativa and has been investigated for its anti-oxidant, anti-inflammatory and anticancer activities in both in vitro and in vivo models since its first extraction in 1960s. Its anti-oxidant/anti-inflammatory effect has been reported in various disease models, including encephalomyelitis, diabetes, asthma and carcinogenesis. Moreover, thymoquinone could act as a free radical and superoxide radical scavenger, as well as preserving the activity of various anti-oxidant enzymes such as catalase, glutathione peroxidase and glutathione-S-transferase. The anticancer effect(s) of thymoquinone are mediated through different modes of action, including anti-proliferation, apoptosis induction, cell cycle arrest, ROS generation and anti-metastasis/anti-angiogenesis. In addition, this quinone was found to exhibit anticancer activity through the modulation of multiple molecular targets, including p53, p73, PTEN, STAT3, PPAR-?, activation of caspases and generation of ROS. The anti-tumor effects of thymoquinone have also been investigated in tumor xenograft mice models for colon, prostate, pancreatic and lung cancer. The combination of thymoquinone and conventional chemotherapeutic drugs could produce greater therapeutic effect as well as reduce the toxicity of the latter. In this review, we summarize the anti-oxidant/anti-inflammatory and anticancer effects of thymoquinone with a focus on its molecular targets, and its possible role in the treatment of inflammatory diseases and cancer.

  • Heat shock protein 27 as a prognostic and predictive biomarker in pancreatic ductal adenocarcinoma.
    Journal of cellular and molecular medicine (2011).Claus Sch?fer, Hendrik Seeliger, Dominik C Bader, Gerald Assmann, Denise Buchner, Yang Guo, Andreas Ziesch, Andreas Palagyi, Stephanie Ochs, R?diger P Laubender, Andreas Jung, Enrico N De Toni, Thomas Kirchner, Burkhard G?ke, Christiane Bruns, Eike Gallmeier et al.A role of heat shock protein 27 (HSP27) as a potential biomarker has been reported in various tumor entities, but comprehensive studies in pancreatic cancer are lacking. Applying tissue microarray (TMA) analysis, we correlated HSP27 protein expression status with clinicopathologic parameters in pancreatic ductal adenocarcinoma specimens from 86 patients. Complementary, we established HSP27 overexpression and RNA-interference models to assess the impact of HSP27 on chemo- and radiosensitivity directly in pancreatic cancer cells. In the TMA study, HSP27 expression was found in 49% of tumor samples. Applying univariate analyses, a significant correlation was found between HSP27 expression and survival. In the multivariate Cox-regression model, HSP27 expression emerged as an independent prognostic factor. HSP27 expression also correlated inversely with nuclear p53 accumulation, indicating either protein interactions between HSP27 and p53 or TP53 mutation-dependent HSP27-regulation in pancreatic cancer. In the sensitivity studies, HSP27 overexpression rendered HSP27 low-expressing PL5 pancreatic cancer cells more susceptible towards treatment with gemcitabine. Vice versa, HSP27 protein depletion in HSP27 high-expressing AsPC-1 cells caused increased gemcitabine resistance. Importantly, HSP27 expression was inducible in pancreatic cancer cell lines as well as primary cells. Taken together, our study suggests a role for HSP27 as a prognostic and predictive marker in pancreatic cancer. Assessment of HSP27 expression could thus facilitate the identification of specific patient subpopulations that might benefit from individualized treatment options. Additional studies need to clarify whether modulation of HSP27 expression could represent an attractive concept to support the incorporation of hyperthermia in clinical treatment protocols for pancreatic cancer.

  • MicroRNA-21 is induced early in pancreatic ductal adenocarcinoma precursor lesions.
    Clinical chemistry (2010). Volume: 56, Issue: 4. Pages: 603-12.Ma?l Chalret du Rieu, J?r?me Torrisani, Janick Selves, Talal Al Saati, Anny Souque, Marl?ne Dufresne, Gregory J Tsongalis, Arief A Suriawinata, Nicolas Carr?re, Louis Buscail, Pierre Cordelier et al.Pancreatic ductal adenocarcinoma (PDAC) has the poorest overall prognosis among gastrointestinal cancers; however, curative resection in early-stage PDAC greatly improves survival rates, indicating the importance of early detection. Because abnormal microRNA production is commonly detected in cancer, we investigated noninvasive precursor pancreatic intraepithelial neoplasia (PanIN) lesions for microRNA production as a potential early biomarker of PDAC.

  • Metastatic pancreatic cancer: is gemcitabine still the best standard treatment? (Review).
    Oncology reports (2010). Volume: 23, Issue: 5. Pages: 1183-92.Mariacristina Di Marco, Roberto Di Cicilia, Marina Macchini, Elisabetta Nobili, Silvia Vecchiarelli, Giovanni Brandi, Guido Biasco et al.Pancreatic ductal adenocarcinoma is the fourth cause of death in the Western world. Surgery remains the only treatment offering an advantage in terms of overall survival (5-year survival range, 15-25%), but unfortunately only 10-20% of patients present resectable disease at the time of diagnosis. Hence chemotherapy, possibly combined with radiation therapy, remains the only treatment option aimed at palliation of symptoms and ensuring a better quality of life. Notwithstanding the efforts to find more effective therapies for the treatment of pancreatic cancer, significant results have not yet been achieved. Increasing interest has focused on integrated treatments, i.e. chemotherapy combined with targeted therapies, and a better selection of patients. This study examines the principal clinical trials that will help give clinicians an overview of the progress made in the systemic therapy for advanced pancreatic cancer patients in recent years.

    Published using Mendeley: The bibliography manager for researchers

  • Gemcitabine sensitivity can be induced in pancreatic cancer cells through modulation of miR-200 and miR-21 expression by curcumin or its analogue CDF.
    Cancer research (2010). Volume: 70, Issue: 9. Pages: 3606-17.Shadan Ali, Aamir Ahmad, Sanjeev Banerjee, Subhash Padhye, Kristin Dominiak, Jacqueline M Schaffert, Zhiwei Wang, Philip A Philip, Fazlul H Sarkar et al.Curcumin induces cancer cell growth arrest and apoptosis in vitro, but its poor bioavailability in vivo limits its antitumor efficacy. We have previously evaluated the bioavailability of novel analogues of curcumin compared with curcumin, and we found that the analogue CDF exhibited greater systemic and pancreatic tissue bioavailability. In this study, we evaluated the effects of CDF or curcumin alone or in combination with gemcitabine on cell viability and apoptosis in gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer (PC) cell lines. Mechanistic investigations revealed a significant reduction in cell viability in CDF-treated cells compared with curcumin-treated cells, which were also associated with the induction of apoptosis, and these results were consistent with the downregulation of Akt, cyclooxygenase-2, prostaglandin E(2), vascular endothelial growth factor, and NF-kappaB DNA binding activity. We have also documented attenuated expression of miR-200 and increased expression of miR-21 (a signature of tumor aggressiveness) in gemcitabine-resistant cells relative to gemcitabine-sensitive cells. Interestingly, CDF treatment upregulated miR-200 expression and downregulated the expression of miR-21, and the downregulation of miR-21 resulted in the induction of PTEN. These results prompt further interest in CDF as a drug modality to improve treatment outcome of patients diagnosed with PC as a result of its greater bioavailability in pancreatic tissue.

  • MicroRNA-21 in pancreatic cancer: correlation with clinical outcome and pharmacologic aspects underlying its role in the modulation of gemcitabine activity.
    Cancer research (2010). Volume: 70, Issue: 11. Pages: 4528-38.Elisa Giovannetti, Niccola Funel, Godefridus J Peters, Marco Del Chiaro, Leyla A Erozenci, Enrico Vasile, Leticia G Leon, Luca E Pollina, Annemieke Groen, Alfredo Falcone, Romano Danesi, Daniela Campani, Henk M Verheul, Ugo Boggi et al.MicroRNA-21 (miR-21) was reported to be overexpressed and contributes to invasion and gemcitabine resistance in pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to evaluate whether miR-21 expression was associated with the overall survival (OS) of PDAC patients treated with gemcitabine and to provide mechanistic insights for new therapeutic targets. miR-21 expression was evaluated in cells (including 7 PDAC cell lines, 7 primary cultures, fibroblasts, and a normal pancreatic ductal cell line) and tissues (neoplastic specimens from 81 PDAC patients and normal ductal samples) isolated by laser microdissection. The role of miR-21 on the pharmacologic effects of gemcitabine was studied with a specific miR-21 precursor (pre-miR-21). Patients with high miR-21 expression had a significantly shorter OS both in the metastatic and in the adjuvant setting. Multivariate analysis confirmed the prognostic significance of miR-21. miR-21 expression in primary cultures correlated with expression in their respective tissues and with gemcitabine resistance. Pre-miR-21 transfection significantly decreased antiproliferative effects and apoptosis induction by gemcitabine, whereas matrix metalloproteinase (MMP)-2/MMP-9 and vascular endothelial growth factor expression were upregulated. Addition of inhibitors of phosphoinositide 3-kinase and mammalian target of rapamycin resulted in decrease of phospho-Akt and prevented pre-miR-21-induced resistance to the proapoptotic effects of gemcitabine. miR-21 expression correlated with outcome in PDAC patients treated with gemcitabine. Modulation of apoptosis, Akt phosphorylation, and expression of genes involved in invasive behavior may contribute to the role of miR-21 in gemcitabine chemoresistance and to the rational development of new targeted combinations.

  • Clinical Potential of MicroRNAs in Pancreatic Ductal Adenocarcinoma.
    Pancreas (2011). Volume: 40, Issue: 8. Pages: 1165-71.Colin W Steele, Karin A Oien, Colin J McKay, Nigel B Jamieson et al.: Aggressive invasion and early metastases are characteristic features of pancreatic ductal adenocarcinoma (PDAC). More than 90% of patients have surgically nonresectable disease at presentation. Despite increasing knowledge of the genetics of this complex disease, systemic therapies, particularly gemcitabine, have modest clinical benefit and marginal survival advantage. MicroRNAs have been shown to have a role in oncogenesis, invasion, and metastases via epigenetic posttranscriptional gene regulation. Our objective was to discuss the clinical impact of microRNAs within PDAC.

  • Somatic mutations in the chromatin remodeling gene ARID1A occur in several tumor types.
    Human mutation (2011).Si?n Jones1, Meng Li, D Williams Parsons, Xiaosong Zhang, Jelle Wesseling, Petra Kristel, Marjanka K Schmidt, Sanford Markowitz, Hai Yan, Darell Bigner, Ralph H Hruban, James R Eshleman, Christine A Iacobuzio-Donahue, Michael Goggins, Anirban Maitra, Sami N Malek, Steve Powell, Bert Vogelstein, Kenneth W Kinzler, Victor E Velculescu, Nickolas Papadopoulos et al.Mutations in the chromatin remodeling gene ARID1A have recently been identified in the majority of ovarian clear cell carcinomas. To determine the prevalence of mutations in other tumor types, we evaluated 759 malignant neoplasms including those of the pancreas, breast, colon, stomach, lung, prostate, brain and blood (leukemias). We identified truncating mutations in 6% of the neoplasms studied; non-truncating somatic mutations were identified in an additional 0.4% of neoplasms. Mutations were most commonly found in gastrointestinal samples with 12 of 119 (10%) colorectal and 10 of 100 (10%) gastric neoplasms, respectively, harboring changes. More than half of the mutated colorectal and gastric cancers displayed microsatellite instability and the mutations in these tumors were out-of-frame insertions or deletions at mononucleotide repeats. Mutations were also identified in 2% to 8% of tumors of the pancreas, breast, brain (medulloblastomas), prostate, and lung, and none of these tumors displayed microsatellite instability. These findings suggest that the aberrant chromatin remodeling consequent to ARID1A inactivation contributes to a variety of different types of neoplasms. ?2011 Wiley Periodicals, Inc.

  • Molecular Determinants of Retinoic Acid Sensitivity in Pancreatic Cancer.
    Clinical cancer research : an official journal of the American Association for Cancer Research (2011).Sonal Gupta, Dipankar Pramanik, Radha Mukherjee, Nathaniel R Campbell, Sathyanarayanan Elumalai, Roeland F Dewilde, Seung-Mo Hong, Michael Goggins, Ana De Jesus-Acosta, Daniel Laheru, Anirban Maitra et al.PURPOSE: To identify a predictive molecular ‘signature’ for sensitivity to retinoic acid in pancreatic cancer. EXPERIMENTAL DESIGN: Fourteen patient-derived, low-passage pancreatic ductal adenocarcinoma (PDAC) lines with varied expression of fatty acid binding protein 5 (FABP5) and cellular retinoic acid binding protein 2 (CRABP2) were used to evaluate the response to all-trans retinoic acid (ATRA). Cell proliferation, apoptosis, and migration/invasion assays were used to measure the in vitro response. Tumor growth was monitored in subcutaneous xenografts in athymic nude mice for 4 weeks. RESULTS: Response to ATRA was observed to be dependent upon differential expression of FABP5 versus CRABP2. Thus, elevated FABP5 expression was associated with minimal cytotoxicity and tumor growth inhibition, and a paradoxical increase in migration and invasion. Conversely, CRABP2 expression in the absence of FABP5 was associated with significant tumor growth inhibition with ATRA, even in gemcitabine-resistant tumors. The ATRA-resistant phenotype of FABP5highCRABP2null cells could be circumvented by ectopic expression of CRABP2. Alternatively, re-expression of endogenous CRABP2 could be enabled in FABP5highCRABP2null PDAC lines by exposure to decitabine and trichostatin A, thereby relieving epigenetic silencing of the CRABP2 gene promoter. Immunohistochemical staining for FABP5 in archival human tissue microarrays identifies a subset of cases (13/63, ~20%) which are negative for FABP5 expression and might be candidates for ATRA therapy. CONCLUSIONS: The widely used agent ATRA deserves a “second look” in PDAC, but needs to be targeted to patient subsets with biopsy-proven FABP5-negative tumors, or be combined with a chromatin modifying agent in order to re-express endogenous CRABP2.

  • Benzyl Isothiocyanate Suppresses Pancreatic Tumor Angiogenesis and Invasion by Inhibiting HIF-?/VEGF/Rho-GTPases: Pivotal Role of STAT-3.
    PloS one (2011). Volume: 6, Issue: 10. Pages: e25799.Srinivas Reddy Boreddy, Ravi P Sahu, Sanjay K Srivastava et al.Our previous studies have shown that benzyl isothiocyanate (BITC) suppresses pancreatic tumor growth by inhibiting STAT-3; however, the exact mechanism of tumor growth suppression was not clear. Here we evaluated the effects and mechanism of BITC on pancreatic tumor angiogenesis. Our results reveal that BITC significantly inhibits neovasularization on rat aorta and Chicken-Chorioallantoic membrane. Furthermore, BITC blocks the migration and invasion of BxPC-3 and PanC-1 pancreatic cancer cells in a dose dependant manner. Moreover, secretion of VEGF and MMP-2 in normoxic and hypoxic BxPC-3 and PanC-1 cells was significantly suppressed by BITC. Both VEGF and MMP-2 play a critical role in angiogenesis and metastasis. Our results reveal that BITC significantly suppresses the phosphorylation of VEGFR-2 (Tyr-1175), and expression of HIF-?. Rho-GTPases, which are regulated by VEGF play a crucial role in pancreatic cancer progression. BITC treatment reduced the expression of RhoC whereas up-regulated the expression of tumor suppressor RhoB. STAT-3 over-expression or IL-6 treatment significantly induced HIF-1? and VEGF expression; however, BITC substantially suppressed STAT-3 as well as STAT-3-induced HIF-1? and VEGF expression. Finally, in vivo tumor growth and matrigel-plug assay show reduced tumor growth and substantial reduction of hemoglobin content in the matrigel plugs and tumors of mice treated orally with 12 ?mol BITC, indicating reduced tumor angiogenesis. Immunoblotting of BITC treated tumors show reduced expression of STAT-3 phosphorylation (Tyr-705), HIF-?, VEGFR-2, VEGF, MMP-2, CD31 and RhoC. Taken together, our results suggest that BITC suppresses pancreatic tumor growth by inhibiting tumor angiogenesis through STAT-3-dependant pathway.

  • Molecular Characteristics of Pancreatic Ductal Adenocarcinoma
    Pathology research international (2011). Pages: 620601.Niki A Ottenhof, Roeland F De Wilde, Anirban Maitra, Ralph H Hruban, G Johan A Offerhaus et al.Pancreatic cancer is an almost universally lethal disease and despite extensive research over the last decades, this has not changed significantly. Nevertheless, much progress has been made in understanding the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) suggesting that different therapeutic strategies based on these new insights are forthcoming. Increasing focus exists on designing the so-called targeted treatment strategies in which the genetic characteristics of a tumor guide therapy. In the past, the focus of research was on identifying the most frequently affected genes in PDAC, but with the complete sequencing of the pancreatic cancer genome the focus has shifted to defining the biological function that the altered genes play. In this paper we aimed to put the genetic alterations present in pancreatic cancer in the context of their role in signaling pathways. In addition, this paper provides an update of the recent advances made in the development of the targeted treatment approach in PDAC.

  • MicroRNAs in pancreatic ductal adenocarcinoma
    Volume: 17, Issue: 7. Pages: 817-827.Jong Y Park, James Helm, Domenico Coppola, Donghwa Kim, Mokenge Malafa, Seung Joon Kim et al.Ductal adenocarcinoma of the pancreas is a lethal cancer for which the only chance of long-term survival belongs to the patient with localized disease in whom a potentially curative resection can be done. Therefore, biomarkers for early detection and new therapeutic strategies are urgently needed. miRNAs are a recently discovered class of small endogenous non-coding RNAs of about 22 nucleotides that have gained attention for their role in downregulation of mRNA expression at the post-transcriptional level. miRNAs regulate proteins involved in critical cellular processes such as differentiation, proliferation, and apoptosis. Evidence suggests that deregulated miRNA expression is involved in carcinogenesis at many sites, including the pancreas. Aberrant expression of miRNAs may upregulate the expression of oncogenes or downregulate the expression of tumor suppressor genes, as well as play a role in other mechanisms of carcinogenesis. The purpose of this review is to summarize our knowledge of deregulated miRNA expression in pancreatic cancer and discuss the implication for potential translation of this knowledge into clinical practice.

  • Frequent loss of expression of the potential tumor suppressor gene DCC in ductal pancreatic adenocarcinoma.
    Cancer Research (1992). Volume: 52, Issue: 9. Pages: 2616-2619.M W H?hne, M E Halatsch, G F Kahl, R J Weinel et al.The development of colon carcinomas is associated with allelic deletions on chromosomes 5q, 17p, and 18q. The DCC gene located on chromosome 18q21.3 codes for a potential tumor suppressor gene related to cellular adhesion receptors. We investigated the expression of this gene in several pancreatic carcinoma cell lines and in patients with ductal adenocarcinomas of the pancreas. In 8 of 11 cell lines and in 4 of 8 primary tumors a complete extinction of DCC gene expression was observed, whereas the c-Ki-ras gene was mutated at codon 12 in 7 of 8 tumors. A highly reduced or absent expression of DCC was found in all low or undifferentiated pancreatic tumor cell lines, whereas in the more differentiated ones DCC expression was conserved. These data suggest that loss of DCC gene expression is an important factor in the development or progress of pancreatic adenocarcinoma and may be linked to the differentiated phenotype of the pancreatic tumor cell.

  • The miR-217 microRNA functions as a potential tumor suppressor in pancreatic ductal adenocarcinoma by targeting KRAS.
    Carcinogenesis (2010). Volume: 31, Issue: 10. Pages: 1726-1733.Wu-Gan Zhao, Shuang-Ni Yu, Zhao-Hui Lu, Yi-Hui Ma, Yu-Mei Gu, Jie Chen et al.Aberrantly expressed microRNA (miRNA) is frequently associated with a variety of cancers, including pancreatic ductal adenocarcinoma (PDAC). In this study, we investigated the expression and possible role of miR-217 in PDAC. Data obtained by locked nucleic acid in situ hybridization and real-time quantitative polymerase chain reaction showed that miR-217 was downregulated in 76.2% (16/21) of PDAC tissues and in all tested PDAC cell lines when compared with the corresponding normal pancreatic tissue. Overexpression of miR-217 in PDAC cells inhibited tumor cell growth and anchorage-independent colony formation and miR-217 decreased tumor cell growth in nude mouse xenografts in vivo. Using in silico predictions, KRAS was defined as a potential direct target of miR-217. Data from the dual-luciferase reporter gene assay showed that KRAS was a direct target of miR-217. Upregulation of miR-217 could decrease KRAS protein levels and reduce the constitutive phosphorylation of downstream AKT. Downregulation of miR-217 expression in PDAC cells could increase cell anchorage-independent colony formation and KRAS protein levels. Furthermore, miR-217 expression was observed to be negatively correlated with KRAS protein expression in PDAC cell lines. We conclude that the frequently downregulated miR-217 can regulate KRAS and function as a tumor suppressor in PDAC. Therefore, miR-217 may serve as a useful therapeutic agent for miRNA-based PDAC therapy.

  • The ARF tumor suppressor inhibits tumor cell colonization independent of p53 in a novel mouse model of pancreatic ductal adenocarcinoma metastasis.
    Molecular cancer research MCR (2011). Volume: 9, Issue: 7. Pages: 867-877.Viviane Palhares Muniz, J Matthew Barnes, Seema Paliwal, Xuefeng Zhang, Xiaoyun Tang, Songhai Chen, Kokou D Zamba, Joseph J Cullen, David K Meyerholz, Shari Meyers, J Nathan Davis, Steven R Grossman, Michael D Henry, Dawn E Quelle et al.Pancreatic ductal adenocarcinoma (PDAC) is an incurable, highly metastatic disease that is largely resistant to existing treatments. A better understanding of the genetic basis of PDAC metastasis should facilitate development of improved therapies. To that end, we developed a novel mouse xenograft model of PDAC metastasis to expedite testing of candidate genes associated with the disease. Human PDAC cell lines BxPC-3, MiaPaCa-2, and Panc-1 stably expressing luciferase were generated and introduced by intracardiac injections into immunodeficient mice to model hematogenous dissemination of cancer cells. Tumor development was monitored by bioluminescence imaging. Bioluminescent MiaPaCa-2 cells most effectively recapitulated PDAC tumor development and metastatic distribution in vivo. Tumors formed in nearly 90% of mice and in multiple tissues, including normal sites of PDAC metastasis. Effects of p14ARF, a known suppressor of PDAC, were tested to validate the model. In vitro, p14ARF acted through a CtBP2-dependent, p53-independent pathway to inhibit MiaPaCa-2-invasive phenotypes, which correlated with reduced tumor cell colonization in vivo. These findings establish a new bioluminescent mouse tumor model for rapidly assessing the biological significance of suspected PDAC metastasis genes. This system may also provide a valuable platform for testing innovative therapies.

  • Synergistic action of Smad4 and Pten in suppressing pancreatic ductal adenocarcinoma formation in mice.
    Oncogene (2010). Volume: 29, Issue: 5. Pages: 674-686.X Xu, B Ehdaie, N Ohara, T Yoshino, C-X Deng et al.Mutations of SMAD4/DPC4 are found in about 60% of human invasive pancreatic ductal adenocarcinomas (PDACs); yet, the manner in which SMAD4 deficiency enhances tumorigenesis remains elusive. Using a Cre-LoxP approach, we generated a mutant mouse carrying a targeted deletion of Smad4 in the pancreas. We showed that the absence of Smad4 alone did not trigger pancreas tumor formation; however, it increased the expression of an inactivated form of Pten, suggesting a role of Pten in preventing Smad4-/- cells from undergoing malignancy. To investigate this, we disrupted both Pten and Smad4. We showed that Pten deficiency initiated widespread premalignant lesions, and a low tumor incidence that was significantly accelerated by Smad4-deficiency. The absence of Smad4 in a Pten-mutant background enhanced cell proliferation and triggered transdifferentiation from acinar, centroacinar and islet cells, accompanied by activation of Notch1 signaling. We showed that all tumors developed in the Smad4/Pten-mutant pancreas exhibited high levels of pAKT and mTOR, and that about 50 and 83% of human pancreatic cancers examined showed increased pAKT and pmTOR, respectively. Besides the similarity in gene expression, the pAKT and/or pmTOR-positive human PDACs and mouse pancreatic tumors also shared some histopathological similarities. These observations indicate that Smad4/Pten-mutant mice mimic the tumor progression of human pancreatic cancers that are driven by activation of the AKT-mTOR pathway, and uncovered a synergistic action of Smad4 and Pten in repressing pancreatic tumorigenesis.

  • SERPINB5 and AKAP12 — Expression and promoter methylation of metastasis suppressor genes in pancreatic ductal adenocarcinoma
    BMC Cancer (2010). Volume: 10, Issue: 1. Pages: 549.Wolf A Mardin, Kostadin O Petrov, Andreas Enns, Norbert Senninger, Joerg Haier, Soeren T Mees et al.Background: Early metastasis and infiltration are survival limiting characteristics of pancreatic ductal adenocarcinoma (PDAC). Thus, PDAC is likely to harbor alterations in metastasis suppressor genes that may provide novel diagnostic and therapeutic opportunities. This study investigates a panel of metastasis suppressor genes in correlation to PDAC phenotype and examines promoter methylation for regulatory influence on metastasis suppressor gene expression and for its potential as a diagnostic tool. Methods: Metastatic and invasive potential of 16 PDAC cell lines were quantified in an orthotopic mouse model and mRNA expression of 11 metastasis suppressor genes determined by quantitative RT-PCR. Analysis for promoter methylation was performed using methylation specific PCR and bisulfite sequencing PCR. Protein expression was determined by Western blot. Results: In general, higher metastasis suppressor gene mRNA expression was not consistent with less aggressive phenotypes of PDAC. Instead, mRNA overexpression of several metastasis suppressor genes was found in PDAC cell lines vs. normal pancreatic RNA. Of the investigated metastasis suppressor genes, only higher AKAP12 mRNA expression was correlated with decreased metastasis (P < 0.05) and invasion scores (P < 0.01) while higher SERPINB5 mRNA expression was correlated with increased metastasis scores (P < 0.05). Both genes’ promoters showed methylation, but only increased SERPINB5 methylation was associated with loss of mRNA and protein expression (P < 0.05). SERPINB5 methylation was also directly correlated to decreased metastasis scores (P < 0.05). Conclusions: AKAP12 mRNA expression was correlated to attenuated invasive and metastatic potential and may be associated with less aggressive phenotypes of PDAC while no such evidence was obtained for the remaining metastasis suppressor genes. Increased SERPINB5 mRNA expression was correlated to increased metastasis and mRNA expression was regulated by methylation. Thus, SERPINB5 methylation was directly correlated to metastasis scores and may provide a diagnostic tool for PDAC.

  • Apoptotic pathways in pancreatic ductal adenocarcinoma
    Molecular Cancer (2008). Volume: 7, Issue: 64. Pages: 64.Rainer Hamacher, Roland M Schmid, Dieter Saur, G?nter Schneider et al.Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer related death. Despite the advances in understanding of the molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. Overall, the 5-year survival rate is less than 5% demonstrating the insufficiency of current therapies. Most cytotoxic therapies induce apoptosis and PDAC cells have evolved a plethora of molecular mechanisms to assure survival. We will present anti-apoptotic strategies working at the level of the death receptors, the mitochondria or involving the caspase inhibitors of the IAP family. Furthermore, the survival function of the phosphotidylinositol-3′ kinase (PI3K)/AKT- and NF-kappaB-pathways are illustrated. A detailed molecular knowledge of the anti-apoptotic mechanisms of PDAC cells will help to improve therapies for this dismal disease and therapeutic strategies targeting the programmed cell death machinery are in early preclinical and clinical development.
  • The tumor suppressor PTEN regulates T cell survival and antigen receptor signaling by acting as a phosphatidylinositol 3-phosphatase.
    The Journal of Immunology (2000). Volume: 164, Issue: 4. Pages: 1934-1939.X Wang, A Gj?rloff-Wingren, M Saxena, N Pathan, J C Reed, T Mustelin et al.The tumor suppressor gene PTEN encodes a 55-kDa enzyme that hydrolyzes both protein phosphotyrosyl and 3-phosphorylated inositol phospholipids in vitro. We have found that the latter activity is physiologically relevant in intact T cells. Expression of active PTEN lead to a 50% loss of transfected cells due to increased apoptosis, which was completely prevented by coexpression of a constitutively active, membrane-bound form of protein kinase B. A mutant of PTEN selectively lacking lipid phosphatase activity, but retaining protein phosphatase activity, had no effects on cell number. Active (but not mutant) PTEN also decreased TCR-induced activation of the mitogen-activated protein kinase ERK2 (extracellular signal-related kinase 2), as seen after inhibition of phosphatidylinositol 3-kinase. Our data indicate that PTEN is a phosphatidylinositol 3-phosphatase in T cells, and we suggest that PTEN may play a role in the regulation of T cell survival and TCR signaling by directly opposing phosphatidylinositol 3-kinase.

  • MicroRNA-150 directly targets MUC4 and suppresses growth and malignant behavior of pancreatic cancer cells.
    Carcinogenesis (2011).Sanjeev K Srivastava, Arun Bhardwaj, Seema Singh, Sumit Arora, Bin Wang, William E Grizzle, Ajay P Singh et al.Pancreatic cancer has the worst prognosis among all cancers due to its late diagnosis and lack of effective therapies. Therefore, identification of novel targets, which are differentially expressed and functionally involved in malignant phenotypes, is critical to achieve early diagnosis and development of effective therapeutic strategies against pancreatic cancer. We have previously shown that MUC4, an aberrantly overexpressed transmembrane mucin, promotes growth, invasion and metastasis of pancreatic cancer cells, thus underscoring its potential as a clinical target. Here, we report a novel microRNA-mediated mechanism underlying aberrant expression of MUC4 in pancreatic cancer. We demonstrate that the 3′ untranslated region (3’UTR) of MUC4 contains a highly conserved miR-150 binding motif and its direct interaction with miR-150 downregulates endogenous MUC4 protein levels. We also show that miR-150-mediated MUC4 downregulation is associated with a concomitant decrease in HER2 and its phosphorylated form, leading to reduced activation of downstream signaling. Furthermore, our findings demonstrate that miR-150 overexpression inhibits growth, clonogenicity, migration and invasion, and enhances intercellular adhesion in pancreatic cancer cells. Finally, our data reveal a downregulated expression of miR-150 in malignant pancreatic tissues, which is inversely associated with MUC4 protein levels. Altogether, these findings establish miR-150 as a novel regulator of MUC4 and a tumor suppressor miRNA in pancreatic cancer.

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About aspenbio

I write software for scientists. I'm interested in Java/Groovy/Grails, the Semantic Web and Cancer Biology.
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