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1.
Biopreserv Biobank ; 15(3): 203-210, 2017 Jun.
Article in English | MEDLINE | ID: mdl-27929677

ABSTRACT

INTRODUCTION: Biosamples and associated clinical data accelerate translational and clinical research discoveries. A lack of high quality biosamples both stalls projects and limits research advances. In this study, we targeted a wide audience of University of California (UC) biobanking stakeholders who were either involved with the collection or the utilization of biosamples to assess the scope of their biobanking activities and their interest in virtual biobanking or cooperating in the formation of the UC-wide biorepository. MATERIALS AND METHODS: Each institutional review board from the five UC medical campuses' provided a dataset of potential researchers involved with biobanking. Once identified, a brief six item web-based questionnaire was administered electronically to these researchers. RESULTS: Most survey participants (80%) responded "yes" (n = 348) that they were actively collecting biosamples for research, and 68% of participants indicated they would either definitely (30%, n = 131) or maybe (38%, n = 166) request biosample materials now or within the next year. An equal proportion of participants responded yes (42% or n = 184) and maybe (42% or n = 182) when asked if they would voluntarily contribute specimens to a UC-wide virtual biobank. DISCUSSION: The results presented above show high levels of support among UC biobanking stakeholders for both requesting material from and contributing material to a UC-wide virtual biobank. In addition, a considerable number of individual researchers on our five UC medical campuses are conducting biospecimen research (i.e., well over n = 435 respondents).


Subject(s)
Biological Specimen Banks , Research Personnel/statistics & numerical data , Biomedical Research/trends , California , Ethics Committees, Research , Humans , Research Personnel/trends , Surveys and Questionnaires , Universities/statistics & numerical data
2.
J Exp Clin Cancer Res ; 33: 93, 2014 Nov 25.
Article in English | MEDLINE | ID: mdl-25422081

ABSTRACT

BACKGROUND: The Hedgehog (Hh) signaling pathway has been implicated in stem cell maintenance and its activation is aberrant in several types of cancer including mesothelioma. Protein kinase CK2 affects several cell signaling pathways through the mechanism of phosphorylation. METHODS: Protein and mRNA levels of CK2α and Gli1 were tested by quantitative RT-PCR and immunohistochemistry staining in mesothelioma samples and cell lines. Down-regulated Gli1 expression and transcriptional activity were demonstrated by RT-PCR, Western blot and luciferase reporter assay. RESULTS: In this study, we show that CK2α is over-expressed and a positive regulator of Hegdehog/Gli1 signaling in human malignant pleural mesothelioma. First of all, we found that the mRNA levels of CK2α and Gli1 were broadly elevated and correlated (n = 52, r = 0.401, P < 0.05), compared with LP9 (a normal mesothelial cell line). We then investigated their expression at the protein level, and found that all the 7 mesothelioma cell lines tested showed positive staining in CK2α and Gli1 immunohistochemistry. Correlation analysis by Pearson test for CK2α and Gli1 expression in the 75 mesothelioma tumors and the 7 mesothelioma cell lines showed that the two protein expression was significantly correlated (n = 82, r = 0.554, P < 0.01). Furthermore, we demonstrated that Gli1 expression and transcriptional activity were down-regulated after CK2α was silenced in two mesothelioma cell lines (H28 and H2052). CK2α siRNA also down-regulated the expression of Hh target genes in these cell lines. Moreover, treatment with a small-molecule CK2α inhibitor CX-4945 led to dose-dependent inhibition of Gli1 expression and transcriptional activity. Conversely, forced over-expression of CK2α resulted in an increase in Gli1 transcriptional activity in H28 cells. CONCLUSIONS: Thus, we report for the first time that over-expressed CK2α positively regulate Hh/Gli1 signaling in human mesothelioma.


Subject(s)
Hedgehog Proteins/metabolism , Lung Neoplasms/enzymology , Mesothelioma/enzymology , Pleural Neoplasms/enzymology , Signal Transduction , Transcription Factors/metabolism , Casein Kinase II/antagonists & inhibitors , Casein Kinase II/genetics , Casein Kinase II/metabolism , Cell Line, Tumor , Dose-Response Relationship, Drug , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Neoplastic , Hedgehog Proteins/genetics , Humans , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Mesothelioma/genetics , Mesothelioma/pathology , Mesothelioma, Malignant , Pleural Neoplasms/genetics , Pleural Neoplasms/pathology , Protein Kinase Inhibitors/pharmacology , RNA Interference , Signal Transduction/drug effects , Transcription Factors/genetics , Transcription, Genetic , Transfection , Zinc Finger Protein GLI1
3.
PLoS One ; 9(6): e98597, 2014.
Article in English | MEDLINE | ID: mdl-24893170

ABSTRACT

Serum microRNAs hold great promise as easily accessible and measurable biomarkers of disease. In prostate cancer, serum miRNA signatures have been associated with the presence of disease as well as correlated with previously validated risk models. However, it is unclear whether miRNAs can provide independent prognostic information beyond current risk models. Here, we focus on a group of low-risk prostate cancer patients who were eligible for active surveillance, but chose surgery. A major criteria for the low risk category is a Gleason score of 6 or lower based on pre-surgical biopsy. However, a third of these patients are upgraded to Gleason 7 on post surgical pathological analysis. Both in a discovery and a validation cohort, we find that pre-surgical serum levels of miR-19, miR-345 and miR-519c-5p can help identify these patients independent of their pre-surgical age, PSA, stage, and percent biopsy involvement. A combination of the three miRNAs increased the area under a receiver operator characteristics curve from 0.77 to 0.94 (p<0.01). Also, when combined with the CAPRA risk model the miRNA signature significantly enhanced prediction of patients with Gleason 7 disease. In-situ hybridizations of matching tumors showed miR-19 upregulation in transformed versus normal-appearing tumor epithelial, but independent of tumor grade suggesting an alternative source for the increase in serum miR-19a/b levels or the release of pre-existing intracellular miR-19a/b upon progression. Together, these data show that serum miRNAs can predict relatively small steps in tumor progression improving the capacity to predict disease risk and, therefore, potentially drive clinical decisions in prostate cancer patients. It will be important to validate these findings in a larger multi-institutional study as well as with independent methodologies.


Subject(s)
MicroRNAs/blood , Prostatic Neoplasms/blood , Prostatic Neoplasms/pathology , Humans , In Situ Hybridization , Male
4.
J Cell Mol Med ; 17(7): 854-62, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23651443

ABSTRACT

Protein kinase CK2 is frequently elevated in a variety of human cancers. The Notch1 signalling pathway has been implicated in stem cell maintenance and its aberrant activation has been shown in several types of cancer including lung cancer. Here, we show, for the first time, that CK2α is a positive regulator of Notch1 signalling in lung cancer cell lines A549 and H1299. We found that Notch1 protein level was reduced after CK2α silencing. Down-regulation of Notch1 transcriptional activity was demonstrated after the silencing of CK2α in lung cancer cells. Furthermore, small-molecule CK2α inhibitor CX-4945 led to a dose-dependent inhibition of Notch1 transcriptional activity. Conversely, forced overexpression of CK2α resulted in an increase in Notch1 transcriptional activity. Finally, the inhibition of CK2α led to a reduced proportion of stem-like CD44 + /CD24- cell population. Thus, we report that the inhibition of CK2α down-regulates Notch1 signalling and subsequently reduces a cancer stem-like cell population in human lung cancer cells. Our data suggest that CK2α inhibitors may be beneficial to the lung cancer patients with activated Notch1 signalling.


Subject(s)
Casein Kinase II/antagonists & inhibitors , Gene Expression Regulation, Neoplastic , Lung Neoplasms/metabolism , Receptor, Notch1/metabolism , Signal Transduction , CD24 Antigen/metabolism , Casein Kinase II/metabolism , Cell Line, Tumor , DNA/metabolism , Dose-Response Relationship, Drug , Down-Regulation , Flow Cytometry , Humans , Hyaluronan Receptors/metabolism , Immunohistochemistry , Naphthyridines/pharmacology , Neoplastic Stem Cells/cytology , Phenazines , Phenotype , RNA, Small Interfering/metabolism , Transcription, Genetic
5.
Cancer Res ; 71(2): 550-60, 2011 Jan 15.
Article in English | MEDLINE | ID: mdl-21098088

ABSTRACT

Recent prostate-specific antigen-based screening trials indicate an urgent need for novel and noninvasive biomarker identification strategies to improve the prediction of prostate cancer behavior. Noncoding microRNAs (miRNA) in the serum and plasma have been shown to have potential as noninvasive markers for physiologic and pathologic conditions. To identify serum miRNAs that diagnose and correlate with the prognosis of prostate cancer, we developed a multiplex quantitative reverse transcription PCR method involving the purification of multiplex PCR products followed by uniplex analysis on a microfluidics chip to evaluate 384 human miRNAs. Using Dgcr8 and Dicer knockout (small RNA-deficient) mouse ES cells as the benchmark, we confirmed the validity of our technique and uncovered a considerable lack of accuracy in previously published methods. Profiling 48 sera from healthy men and untreated prostate cancer patients with differing CAPRA scores, we identified miRNA signatures that allow us to diagnose cancer patients and correlate with a prognosis. These serum signatures include oncogenic and tumor-suppressive miRNAs, suggesting functional roles in prostate cancer progression.


Subject(s)
MicroRNAs/blood , Microfluidic Analytical Techniques/methods , Prostatic Neoplasms/blood , Prostatic Neoplasms/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , Case-Control Studies , Humans , Male , MicroRNAs/genetics , Prognosis , Prostatic Neoplasms/diagnosis
6.
Proteomics Clin Appl ; 3(5): 516-527, 2009 May 05.
Article in English | MEDLINE | ID: mdl-19834583

ABSTRACT

Cervical cancer originates with human papillomavirus (HPV) infection and progresses via histologically-defined premalignant stages. Here we compare normal cervical epithelium and patient-matched high grade squamous intraepithelial lesions (HSIL) with cervical carcinoma tissue from the same patient population (n=10 per group). Specimens were analyzed by combined laser capture microdissection and 2D-DIGE. Significant expression changes were seen with 53 spots resulting in identification of 23 unique proteins at the molecular level. These include eight that uniquely distinguish normal epithelium and HSIL and four that uniquely distinguish HSIL and carcinoma. In addition, one protein, cornulin, distinguishes all three states. Other identified proteins included differentiation markers, oncogene DJ-1, serpins, stress and interferon-responsive proteins, detoxifying enzymes, and serum transporters. A literature review, performed for all identified proteins, allowed most changes to be assigned to one of three causes: direct or indirect HPV oncoprotein interactions, growth selection during latency, or interactions in the lesion microenvironment. Selected findings were confirmed by immunohistochemistry using either frozen sections from the same cohort or formalin fixed paraffin embedded samples from a tissue microarray. Novel markers described here have potential applications for increasing the predictive value of current screening methods.

7.
Proteome Sci ; 7: 29, 2009 Aug 23.
Article in English | MEDLINE | ID: mdl-19698150

ABSTRACT

BACKGROUND: Infection with high-risk type human papilloma viruses (HPVs) is associated with cervical carcinomas and with a subset of head and neck squamous cell carcinomas. Viral E6 and E7 oncogenes cooperate to achieve cell immortalization by a mechanism that is not yet fully understood. Here, human keratinocytes were immortalized by long-term expression of HPV type 16 E6 or E7 oncoproteins, or both. Proteomic profiling was used to compare expression levels for 741 discrete protein features. RESULTS: Six replicate measurements were performed for each group using two-dimensional difference gel electrophoresis (2D-DIGE). The median within-group coefficient of variation was 19-21%. Significance of between-group differences was tested based on Significance Analysis of Microarray and fold change. Expression of 170 (23%) of the protein features changed significantly in immortalized cells compared to primary keratinocytes. Most of these changes were qualitatively similar in cells immortalized by E6, E7, or E6/7 expression, indicating convergence on a common phenotype, but fifteen proteins (~2%) were outliers in this regulatory pattern. Ten demonstrated opposite regulation in E6- and E7-expressing cells, including the cell cycle regulator p16INK4a; the carbohydrate binding protein Galectin-7; two differentially migrating forms of the intermediate filament protein Cytokeratin-7; HSPA1A (Hsp70-1); and five unidentified proteins. Five others had a pattern of expression that suggested cooperativity between the co-expressed oncoproteins. Two of these were identified as forms of the small heat shock protein HSPB1 (Hsp27). CONCLUSION: This large-scale analysis provides a framework for understanding the cooperation between E6 and E7 oncoproteins in HPV-driven carcinogenesis.

8.
Schizophr Bull ; 35(2): 437-42, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19279086

ABSTRACT

INTRODUCTION: Recent studies suggest that in addition to factors such as treatment side effects, suicide, and poor health habits, people with schizophrenia may have an increased risk of diabetes prior to antipsychotic treatment. Diabetes is associated with an increased pulse pressure (PP) and a shortened telomere. We tested the hypothesis that prior to antipsychotic treatment, schizophrenia and related disorders are associated with a shortened telomere, as well as an increased PP. METHODS: Telomere content (which is highly correlated with telomere length) and PP were measured in newly diagnosed, antipsychotic-naive patients with schizophrenia and related disorders on first clinical contact and in matched control subjects. Both groups were also administered an oral glucose tolerance test. RESULTS: Compared with control subjects, the patients with psychosis had decreased telomere content and an increased PP. As previously reported, they also had increased glucose concentrations at 2 hours. These differences could not be attributed to differences in age, ethnicity, smoking, gender, body mass index, neighborhood of residence, socioeconomic status, aerobic conditioning, or an increased cortisol concentration in the psychotic subjects. DISCUSSION: These results suggest that prior to antipsychotic use, nonaffective psychosis is associated with reduced telomere content and increased PP, indices that have been linked to an increased risk of diabetes and hypertension.


Subject(s)
Blood Pressure/physiology , Schizophrenia/diagnosis , Telomere/metabolism , Adolescent , Adult , Aging/physiology , Antipsychotic Agents/adverse effects , Antipsychotic Agents/therapeutic use , Blood Pressure/genetics , Diabetes Mellitus/blood , Diabetes Mellitus/metabolism , Diastole/genetics , Diastole/physiology , Female , Glucose Tolerance Test , Humans , Hydrocortisone/blood , Leukocytes/metabolism , Male , Middle Aged , Psychiatric Status Rating Scales , Psychotic Disorders/blood , Psychotic Disorders/diagnosis , Psychotic Disorders/genetics , Schizophrenia/genetics , Schizophrenia/metabolism
9.
In Vivo ; 21(2): 279-83, 2007.
Article in English | MEDLINE | ID: mdl-17436577

ABSTRACT

BACKGROUND: The green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) possesses anti-carcinogenic properties and was found to induce terminal differentiation in epidermal keratinocytes. Caspase-14, a member of the caspase family associated with epithelial cell differentiation, planned cell death, and barrier formation, is induced by EGCG in normal human epidermal keratinocytes but not in cancer cells. MATERIALS AND METHODS: A human epidermoid cancer cell line, A431, was co-transfected with a caspase-14-expressing pCMV vector and a GFP/neo-etpressingpCMVvector. Cell growth and tumorigenicity of the stable transfectant were determined in comparison to cells transfected with the control GFP/neo-expressing pCMV vector. RESULTS: Expression of exogenous caspase-14 led to growth inhibition and reduced the tumorigenicity of A431 cells. CONCLUSION: Pending future studies, caspase-14 could be used as a novel approach to skin cancer therapy via gene delivery systems.


Subject(s)
Caspase 14/genetics , Skin Neoplasms/prevention & control , Animals , Anticarcinogenic Agents/pharmacology , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/prevention & control , Catechin/analogs & derivatives , Catechin/pharmacology , Cell Division/drug effects , Cell Line, Tumor , Humans , Male , Mice , Mice, Nude , RNA, Small Interfering/genetics , Skin Neoplasms/pathology , Transplantation, Heterologous
10.
Autoimmunity ; 40(2): 138-47, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17364504

ABSTRACT

Sjogren's syndrome (SS) is a relatively common autoimmune disorder. A key feature of SS is lymphocytic infiltration of the salivary and lacrimal glands, associated with the destruction of secretory functions of these glands. Current treatment of SS targets the symptoms but is unable to reduce or prevent the damage to the glands. We reported previously that the major green tea polyphenol (GTP) epigallocatechin-3-gallate (EGCG) inhibits autoantigen expression in normal human keratinocytes and immortalized normal human salivary acinar cells (Hsu et al. 2005). However, it is not known whether GTPs have this effect in vivo, if they can reduce lymphocytic infiltration, or protect salivary acinar cells from tumor necrosis factor-alpha (TNF-alpha)-induced cytotoxicity. Here, we demonstrate that in the NOD mouse, a model for human SS, oral administration of green tea extract reduced the serum total autoantibody levels and the autoimmune-induced lymphocytic infiltration of the submandibular glands. Further, we show that EGCG protected normal human salivary acinar cells from TNF-alpha-induced cytotoxicity. This protection was associated with specific phosphorylation of p38 MAPK, and inhibitors of the p38 MAPK pathway blocked the protective effect. In conclusion, GTPs may provide a degree of protection against autoimmune-induced tissue damage in SS, mediated in part through activation of MAPK elements.


Subject(s)
Autoimmunity , Flavonoids/pharmacology , Phenols/pharmacology , Plant Extracts/pharmacology , Salivary Glands/drug effects , Sjogren's Syndrome/immunology , Tea/chemistry , Tumor Necrosis Factor-alpha/physiology , Animals , Catechin/analogs & derivatives , Catechin/pharmacology , Cell Line , Cell Survival/drug effects , Disease Models, Animal , Humans , Imidazoles/pharmacology , Lymphocytes/immunology , Lymphocytes/pathology , MAP Kinase Kinase 4/metabolism , MAP Kinase Kinase Kinases/antagonists & inhibitors , Mice , Mice, Inbred NOD , Phosphorylation , Polyphenols , Pyridines/pharmacology , Salivary Glands/pathology , Sjogren's Syndrome/pathology , Tumor Necrosis Factor-alpha/pharmacology , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors
11.
J Pharmacol Exp Ther ; 315(2): 805-11, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16046615

ABSTRACT

Autoimmune disorders, characterized by inflammation and apoptosis of target cells leading to tissue destruction, are mediated in part by autoantibodies against normal cellular components (autoantigens) that may be overexpressed. For example, antibodies against the autoantigens SS-A/Ro and SS-B/La are primary markers for systemic lupus erythematosus and Sjögren's syndrome. Recently, studies in animals demonstrated that green tea consumption may reduce the severity of some autoimmune disorders, but the mechanism is unclear. Herein, we sought to determine whether the most abundant green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), affects autoantigen expression in human cells. Cultures of pooled normal human primary epidermal keratinocytes and of an immortalized human salivary acinar cell line were incubated with 100 microM EGCG (a physiologically achievable level for topical application or oral administration) for various time periods and then analyzed by cDNA microarray analysis, reverse transcription-polymerase chain reaction, and Western blotting for expression of several major autoantigen candidates. EGCG inhibited the transcription and translation of major autoantigens, including SS-B/La, SS-A/Ro, coilin, DNA topoisomerase I, and alpha-fodrin. These findings, taken together with green tea's anti-inflammatory and antiapoptotic effects, suggest that green tea polyphenols could serve as an important component in novel approaches to combat autoimmune disorders in humans.


Subject(s)
Autoantigens/biosynthesis , Catechin/analogs & derivatives , Blotting, Western , Catechin/pharmacology , Cell Line , Down-Regulation/drug effects , Humans , Keratinocytes/drug effects , Keratinocytes/immunology , Oligonucleotide Array Sequence Analysis , RNA/biosynthesis , RNA/genetics , Reverse Transcriptase Polymerase Chain Reaction , Salivary Glands/cytology , Salivary Glands/drug effects , Salivary Glands/immunology
12.
Proteomics ; 5(7): 1746-57, 2005 May.
Article in English | MEDLINE | ID: mdl-15761955

ABSTRACT

Laser capture microdissection (LCM) provides the capability to isolate and analyze small numbers of cells from a specific area of a histologic section. LCM has particular value for analysis of early stage tumors, which are often small and intermixed with non-tumor tissue. It has previously been shown that a new generation of cysteine-reactive cyanine dyes can, in principle, provide increased sensitivity for two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) profiling when sample quantitities are limiting. However, the comparative advantage of the new dyes in a clinical setting has not been established. Here, we report that cysteine-reactive dyes allowed the identification of more features than established, lysine-reactive dyes with a given number of cells. This was true both with extracts prepared from human papillomavirus E6 and E7-transduced human keratinocytes, a model for early-stage cervical cancer, and with LCM samples. In an experiment comparing LCM clinical samples of gastric adenocarcinoma versus precancerous, spasmolytic polypeptide expressing metaplasia (SPEM) from the same patient, cysteine labeling allowed the identification of more than 1000 discrete protein spots in samples containing 5000 cells. This is a 5- to 50-fold smaller sample than used in previous studies. Both labeling methods had a comparable success rate for protein identification by mass spectrometry (MS). The proteins associated with more than 40 differentially abundant spots in the clinical samples were identified by MS. In this exploratory analysis, changes in expression levels of cytoskeletal proteins, molecular chaperones, and cell-signaling proteins were seen. The identification of a number of proteins that are potentially relevant to tumor progression suggests that the method holds promise for biomarker discovery.


Subject(s)
Carbocyanines/metabolism , Cysteine , Fluorescent Dyes/metabolism , Proteomics/methods , Staining and Labeling/methods , Adenocarcinoma/metabolism , Biomarkers , Cells, Cultured , Humans , Keratinocytes/metabolism , Lasers , Microdissection/methods , Stomach Neoplasms/metabolism
13.
Radiology ; 228(2): 488-92, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12801999

ABSTRACT

PURPOSE: To design and evaluate a construct that allows regulated expression of the magnetic resonance (MR) imaging reporter gene human tyrosinase under control of the tetracycline response element. MATERIALS AND METHODS: A breast cancer cell line (MCF-7) was transfected with a plasmid that codes for the tetracycline-controlled transactivator and a new construct. In this construct, the reporter gene human tyrosinase is under control of the tetracycline response element, thus allowing suppression of gene expression by adding doxycycline (tetracycline switched off). A reverse transcription polymerase chain reaction was conducted to evaluate gene expression. Additionally, immunohistochemical investigation of tyrosinase and melanin staining was undertaken to analyze the presence of these molecules. After culture in an iron- and holotransferrin-enriched medium, cells were imaged in a 1.0-T clinical MR imager by using a surface coil and T1-weighted spin-echo and gradient-echo sequences. RESULTS: Two stable transfected cell clones were established. Cells cultured with doxycycline showed no background expression of the human tyrosinase gene, whereas withdrawal of doxycycline resulted in detectable tyrosinase messenger RNA expression. Gene expression results in a detectable tyrosinase protein level and melanin content. Increased signal intensity on T1-weighted MR images in cells that expressed the reporter gene was observed in comparison to genetically identical cells with the reporter gene switched off. CONCLUSION: Our construct enables MR imaging of regulated tyrosinase gene expression in vitro.


Subject(s)
Breast Neoplasms/genetics , Gene Expression , Genes, Reporter , Magnetic Resonance Imaging , Monophenol Monooxygenase/genetics , Doxycycline/pharmacology , Humans , In Vitro Techniques , Plasmids , Reverse Transcriptase Polymerase Chain Reaction , Statistics, Nonparametric , Tetracycline/pharmacology , Transfection/methods , Tumor Cells, Cultured
14.
Virology ; 299(1): 72-87, 2002 Jul 20.
Article in English | MEDLINE | ID: mdl-12167343

ABSTRACT

The group of mucosal epithelia-infecting human papillomaviruses (HPV) can be subdivided in "low" and "high risk" HPV types. Both types induce benign neoplasia (condyloma), but only the infection with a "high risk" HPV type is causally associated with an increased risk of developing anogenital tumors. The oncogenic potential of high risk HPVs resides at least partially in the viral E6 protein. The E6 protein targets the cellular p53 protein for proteasome-dependent degradation, which is associated with the immortalizing and transforming functions of these viruses. Recently the E6-dependent proteasome-mediated destabilization of additional cellular proteins (E6TP1, c-myc, Bak, hMCM7, human scribble, E6AP, MAGI-1) has been described, but the cellular mechanisms controlling the viral E6 protein stability itself have been so far not analyzed. In this study, we transiently expressed the E6 genes of the high risk HPV type 16, the low risk HPV types 6a and 11, and the cutaneous epithelia-infecting HPV types 5 and 8 from a eucaryotic expression vector and compared the cellular steady-state levels of the expressed E6 proteins. We demonstrated that the high risk HPV 16 E6 protein possesses the lowest steady-state level in comparison to the low risk HPV type E6 proteins and the cutaneous epithelia-infecting HPV type E6 proteins. Inhibition of cellular proteasome-dependent protein degradation led to an increase in steady-state levels of high risk but not of low risk E6 proteins. Analysis of functionally deficient HPV 16 E6 proteins in p53 null- and p53 wild-type-expressing cell lines revealed that the cellular steady-state level of this protein is influenced neither by its p53- nor its E6AP-binding abilities.


Subject(s)
Ligases/metabolism , Oncogene Proteins, Viral/metabolism , Papillomaviridae/metabolism , Repressor Proteins , Tumor Suppressor Protein p53/metabolism , Animals , Antineoplastic Agents/pharmacology , COS Cells , Chlorocebus aethiops , Cysteine Endopeptidases , Gene Deletion , Humans , Leupeptins/pharmacology , Multienzyme Complexes/antagonists & inhibitors , Oncogene Proteins, Viral/analysis , Oncogene Proteins, Viral/genetics , Papillomavirus Infections/virology , Proteasome Endopeptidase Complex , Tumor Cells, Cultured , Tumor Suppressor Protein p53/genetics , Tumor Virus Infections/virology , Ubiquitin-Protein Ligases
15.
Proteomics ; 2(6): 697-705, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12112851

ABSTRACT

Tumors of the pancreas are characterized by a high intrinsic potency to develop chemoresistance towards cytotoxic drugs, which is the main cause of ineffective treatment. The phenomenon of multidrug resistance is known to be a multifactorial event in which several mechanisms act simultaneously. We investigated the response of pancreas tumor cells after exposure to the anthracycline daunorubicin (DRC), a well-known antitumor agent in chemotherapy, by two-dimensional gel electrophoresis (2-DE). DRC is known to cause DNA damage and to affect tumor cell growth. Importantly, we aimed at investigating alterations in the protein expression pattern after first contact of the tumor cells with DRC, thus simulating a situation close to clinical chemotherapy and elucidating cell survival strategies following initial drug exposure. A concentration dependent up-regulation of a variety of proteins was observed, indicating that cell response to DRC involves multiple signaling events. Since the p53 tumor suppressor is essentially involved in the regulation of cell growth and controlled cell death (apoptosis) after cellular stress (like DNA damage), we investigated the role of p53 in DRC-resistant and -sensitive pancreas carcinoma cells by measuring p53 transcriptional transactivation activities. No differences in p53 activities were observed in response to DRC treatment in both pancreas cell lines, whereas mamma carcinoma cells (MCF-7), possessing wild-type p53, demonstrated the expected increase in p53 transcriptional transactivation activity. Hence, the tested pancreas carcinoma cells harbor a mutant, nonfunctional p53. We additionally analyzed the steady state protein levels of the cyclin dependent kinase inhibitor p21(CIP1), which is known to be involved in cell cycle control. Interestingly, p21(CIP1 )was induced by DRC in sensitive cells in a concentration dependent manner and was highest in resistant cells. In conclusion, our results suggest that the induction of proteins by DRC in pancreas carcinoma cells, as observed by 2-DE, occurs independently from p53 signaling events, but is probably associated with increased levels of p21(CIP1).


Subject(s)
Antibiotics, Antineoplastic/pharmacology , DNA Damage , Daunorubicin/pharmacology , Electrophoresis, Gel, Two-Dimensional/methods , Pancreatic Neoplasms/drug therapy , Blotting, Western , Cyclin-Dependent Kinase Inhibitor p21 , Cyclins/metabolism , Drug Resistance, Neoplasm/genetics , Gene Expression/drug effects , Humans , Pancreatic Neoplasms/metabolism , Signal Transduction , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Transcriptional Activation , Transfection , Tumor Cells, Cultured , Tumor Suppressor Protein p53/metabolism , Up-Regulation
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