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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously established a line of immortalized normal human articular chondrocytes, lbpva55, expressing the E6 and E7 transforming genes of the human papilloma virus type 16. With this study we investigated the phenotypic modulation ability of this cell line, cultured in different conditions, with the aim of validating its use for studies on cartilage metabolism and physiology. To this end, we performed a quantitative analysis, using real-time PCR technology, of the expression of the main structural components of the cartilage matrix (collagens I, II and aggrecan), of two transcription factors regulating chondrocyte differentiation (Sox-9 and Egr-1) and of some enzymes involved in matrix turnover (cathepsin B, MMP-1 and MMP-13). Results showed that, under defined conditions, lbpva55 cells were able to re-express the chondrocyte phenotype that was lost in a conventional monolayer condition, as demonstrated by an up-regulation of collagen II, the main marker of hyaline cartilage and Sox-9, a master gene regulator of chondrocytic differentiation. The gene expression profile of our immortalized cells compared with that of normal articular chondrocytes showed that this line could be used as a valid in vitro model for a better understanding of cell molecular mechanisms relevant for the development of new therapeutic approaches in rheumatic diseases and for the cartilage engineering field.
Int J Mol Med 2007 Jan
PMID:Induction of original phenotype of human immortalized chondrocytes: a quantitative gene expression analysis. 1714 52

A naked DNA vaccine delivered by gene gun into antigen-presenting cells (APCs) has emerged as an attractive strategy for antigen-specific cancer immunotherapy. However, APCs have a limited lifespan, hindering their long-term ability to prime antigen-specific T cells. Furthermore, the potency of DNA vaccines is limited by their inability to process and present antigens. Interleukin-6 (IL-6) could play a role in immunity and cell apoptosis. We explored how the DNA vaccine encodes IL-6 to a model tumor antigen, human papilloma virus type-16 (HPV-16) E7. Mice vaccinated with IL-6/E7 DNA exhibited dramatic increases in E7-specific T-cell immunities, anti-E7 antibody responses, and impressive anti-tumor effects against E7-expressing tumors. The in vitro results revealed that IL-6 enhances DNA vaccine potency through the major histocompatibility complex class I pathway via direct and cross-priming effects. In addition, the delivery of IL-6/E7 DNA prolonged the survival of transduced dendritic cells (DCs) in vivo. Our results indicated that the IL-6/E7 DNA vaccine combined the mechanisms of enhancing antigen processing and presentation with prolonging the survival of DCs. Using IL-6 represents an innovative approach to enhancing DNA vaccine potency and holds promise for cancer prevention and immunotherapy.
Mol Ther 2007 Oct
PMID:IL-6-encoding tumor antigen generates potent cancer immunotherapy through antigen processing and anti-apoptotic pathways. 1760 58

Inactivation of tumor suppressor p53 accompanies the majority of malignant diseases in humans. Restoration of p53 functions in tumor results in death of cancer cells, which can be used in cancer therapy. In cervical cancer a product of E6 gene of the human papilloma virus promotes accelerated degradation of p53 in proteasome system. Therefore, one of the approaches to reactivation of p53 in cervical carcinoma cells could be the use of small molecules that inhibit functions of viral proteins. By using as a test system human cervical carcinoma cells (HeLa cell line bearing human papilloma virus type 18, HPV-18) with introduced reporter construct that expresses beta-galactosidase under control of a p53-dependent promoter we carried out screening of a library of small molecules to select small molecules capable of reactivating transcriptional activity of p53. We then characterized the effects of two most active compounds in cell lines that differ in the status of p53-dependent signaling pathway. Both of the compounds caused specific activation of p53 in the cell lines expressing HPV-18, to a lesser extent--HPV-16, and do not cause any effect in control p53 negative cells, or in the cells with undisrupted p53 pathway. Activation of p53 in cervical carcinoma cells was accompanied by the induction of the p53-dependent gene CDKN1 (p21), by inhibition of proliferation, and by the induction of apoptosis. Both of the compounds were capable of deep inhibition of transcription from the HPV genome, which apparently was the cause for p53 reactivation in response to decreased expression of the E6 protein. The observed low toxicity for normal cells allows considering these chemical compounds as prototypes for future anticancer drugs.
Mol Biol (Mosk)
PMID:[Transcriptional inhibition of human papilloma virus in cervical carcinoma cells reactivates functions of the tumor suppressor p53]. 1768 29

The thymidine analogue 4-thiothymidine (S(4)TdR) is a photosensitizer for UVA radiation. The UV absorbance spectrum of S(4)TdR and its incorporation into DNA suggests that it might act synergistically with nonlethal doses of UVA to selectively kill hyperproliferative or cancerous skin cells. We show here that nontoxic concentrations of S(4)TdR combine with nonlethal doses of UVA to kill proliferating cultured skin cells. Established cell lines with a high fraction of proliferating cells were more sensitive than primary keratinocytes or fibroblasts to apoptosis induction by S(4)TdR/UVA. Although S(4)TdR plus UVA treatment induces stabilization of p53, cell death, as measured by apoptosis or clonal survival, occurs to a similar extent in both p53 wild-type and p53-null backgrounds. Furthermore, different types of human papilloma virus E6 proteins, which protect against UVB-induced apoptosis, have little effect on killing by S(4)TdR/UVA. S(4)TdR/UVA offers a possible therapeutic intervention strategy that seems to be applicable to human papilloma virus-associated skin lesions.
Mol Cancer Ther 2007 Sep
PMID:Thiothymidine plus low-dose UVA kills hyperproliferative human skin cells independently of their human papilloma virus status. 1787 46

The purification of "difficult" proteins for structural and functional studies remains a challenge. A widely used approach is their production as fusions with an affinity tag, so that a generic tag-based purification protocol can be applied. Alternatively, immuno-affinity using a protein-specific antibody allows purification of unmodified proteins in a single step, if mild elution conditions can be identified for dissociating the complex without disrupting the folding of the protein. Here, we describe a quantitative structure activity relationship (QSAR) strategy to predict optimized elution conditions from a mathematical model that relates target/antibody dissociation to environmental changes. We illustrate the strategy with the E6 protein of the human papilloma virus (HPV) 16, a highly unstable protein central to HPV-induced carcinogenesis. Surface plasmon resonance (SPR) was used to measure the kinetics of dissociation of an E6 peptide from an E6-specific antibody in a set of multivariate conditions, where three environmental factors (pH, NaCl concentration, and temperature) were varied. The QSAR model indicated that dissociation is favored at pH < 5, which is detrimental to E6 folding, and also at pH > or = 10 if the temperature is high. We verified that the conclusions of the QSAR study with the peptide were valid for the scFv1F4/E6 protein complex, and that the recovered protein was capable of mediating p53 degradation. Finally, we demonstrated that the optimized elution conditions (pH 10, 35 degrees C) were adequate for purifying the recombinant E6 protein from crude cell extracts.
J Mol Recognit
PMID:SPR identification of mild elution conditions for affinity purification of E6 oncoprotein, using a multivariate experimental design. 1805 Mar 61

Cervical cancer is the second most common malignant neoplasm in women, in terms of incidence and mortality rates worldwide, and is associated with excessive inflammation. This involves the expression of both pro- and anti-apoptotic proteins that have varied effect on tumor growth and metastasis. The objective of the present study was to elucidate the effect of hydrogen peroxide (H2O2) on apoptotic signal molecules in vitro in SiHa and CaSki cell lines expressing the human papilloma virus 16 E6 protein, which causes the ubiquitin-mediated degradation of p53 protein and is thus p53 deficient. The p53 is known to act as a cellular stress sensor and triggers apoptosis. We demonstrate, here, that in HPV 16 positive cell lines apoptosis is triggered by upregulation of p73, which causes activation of pro-apoptotic Bax accompanied by down regulation of anti-apoptotic Bcl xl, release of cytochrome c from mitochondria and activation of caspases-9 and -3.
Mol Cell Biochem 2008 Mar
PMID:Induction of apoptosis by hydrogen peroxide in HPV 16 positive human cervical cancer cells: involvement of mitochondrial pathway. 1806 Apr 74

E6-AP is a founding member of HECT (homologous to E6-AP C terminus) domain subfamily of E3 ubiquitin ligases. It degrades tumor suppressor p53 in association with the E6 oncoprotein of the human papilloma virus. However, there are conflicting reports on its role in the degradation of p53 in the absence of E6 oncoprotein. Here, we studied the role of E6-AP in regulation of p53 in mouse neuro 2a cells. Overexpression of E6-AP in neuro 2a cells increased the ubiquitylation and degradation of p53, which could be prevented upon deletion of HECT domain. E6-AP also directly ubiquitylated p53 in an in vitro ubiquitylation assay. Partial knockdown of E6-AP increased the levels of p53 and p53-dependent transcription. Partial knockdown also increased neuronal cell death, which may be mediated partly via p53. Our result suggests that E6-AP not only enhances the degradation of p53 but also regulates the neuronal cell growth.
Cell Mol Life Sci 2008 Feb
PMID:Regulation of turnover of tumor suppressor p53 and cell growth by E6-AP, a ubiquitin protein ligase mutated in Angelman mental retardation syndrome. 1819 66

Alloferon is a 13-amino acid peptide isolated from the bacteria-challenged larvae of the blow fly Calliphora vicina. The pharmaceutical value of the peptide has been well demonstrated by its capacity to stimulate NK cytotoxic activity and interferon (IFN) synthesis in animal and human models, as well as to enhance antiviral and antitumor activities in mice. Antiviral and the immunomodulatory effectiveness of alloferon have also been supported clinically proved in patients suffering with herpes simplex virus (HSV) and human papilloma virus (HPV) infections. To elucidate molecular response to alloferon treatment, we initially screened a model cell line in which alloferon enhanced IFN synthesis upon viral infection. Among the cell lines tested, Namalva was chosen for further proteomic analysis. Fluorescence difference gel electrophoresis (DIGE) revealed that the levels of a series of antioxidant proteins decreased after alloferon treatment, while at least three glycolytic enzymes and four heat-shock proteins were increased in their expression levels. Based on the result of our proteomic analysis, we speculated that alloferon may activate the NF-kappaB signaling pathway. IkappaB kinase (IKK) assay, Western blot analysis on IkappaBalpha and its phosphorylated form at Ser 32, and an NF-kappaB reporter assay verified our proteomics-driven hypothesis. Thus, our results suggest that alloferon potentiates immune cells by activating the NF-kappaB signaling pathway through regulation of redox potential. Since NF-kappaB activation is involved in IFN synthesis, our results provide further clues as to how the alloferon peptide may stimulate IFN synthesis.
Mol Cell Biochem 2008 Jun
PMID:Activation of NF-kappaB by alloferon through down-regulation of antioxidant proteins and IkappaBalpha. 1836 38

Breast carcinoma (BC) is a prevalent malignant tumour occurring in women. Many studies have indicated the role of human papilloma virus type 16 (HPV16) in the pathogenesis of BC; however, the correlations of HPV16 infection with the clinicopathologic features of BC and the expressions of c-erbB-2 and bcl-2 have not yet been elucidated. In this study, HPV16 was detected by amplifying the HPV16 E6 gene by the polymerase chain reaction method, and the expressions of c-erbB-2 and bcl-2 in 40 BCs and 20 normal breast tissue samples, obtained from Shaanxi Province, were examined using the streptavidin-peroxidase method with monoclonal antibodies specific to c-erbB-2 and bcl-2. The infection rate of HPV16 E6 and the positive expression rate of c-erbB-2 were significantly higher in the BCs than in the normal tissues (HPV16 E6: 60% vs. 5%; c-erbB-2: 42.5% vs. 5%, P < 0.05). However, the positive expression rate of bcl-2 was significantly lower in the BCs than in the normal tissues (67.5% vs. 95%, P < 0.05). The infection rate of HPV16 did not correlate with any of the pathological features observed (P > 0.05). HPV16 infection correlated with bcl-2 expression (P = 0.015) but not with c-erbB-2 expression (P = 0.747) in the BCs. Interestingly, HPV16 infection correlated with bcl-2 expression in grade I BCs (P = 0.018) but not in grade II-III BCs (P = 0.633). Our data suggest that HPV16 infection is correlated with bcl-2 expression in BCs.
Mol Biol Rep 2009 Apr
PMID:The correlations between HPV16 infection and expressions of c-erbB-2 and bcl-2 in breast carcinoma. 1842 47

High-risk human papilloma virus (HPV) encodes two oncoproteins, E6 and E7, which are vital to viral replication and contribute to the development of cervical cancer. HPV16 E7 can target over 20 cellular proteins, but is best known for inactivating the retinoblastoma (RB) tumor suppressor. RB functions by restraining cells from entering S-phase of the cell cycle, thus preventing aberrant proliferation. While it is well established that HPV16 E7 facilitates the degradation of the RB protein, the ability of the RB pathway to overcome E7 action is less well understood. In this study the RB-pathway was activated via the overexpression of the p16ink4a tumor suppressor or ectopic expression of an active allele of RB (PSM-RB). While p16ink4a had no influence on cell cycle progression, PSM-RB expression was sufficient to induce a cell cycle arrest in both SiHa and HeLa cells, HPV positive cervical cancer cell lines. Strikingly, this arrest led to the downregulation of E2F target gene expression, which was antagonized via enhanced HPV-E7 expression. Since downmodulation of E7 function is associated with chronic growth arrest and senescence, the effect of PSM-RB on proliferation and survival was evaluated. Surprisingly, sustained PSM-RB expression impeded the proliferation of SiHa cells, resulting in both cell cycle inhibition and cell death. From these studies we conclude that active RB expression can sensitize specific cervical cancer cells to cell cycle inhibition and cell death. Thus, targeted therapies involving activation of RB function may be effective in inducing cell death in cervical cancer.
Mol Carcinog 2009 Jan
PMID:Activation of the retinoblastoma tumor suppressor mediates cell cycle inhibition and cell death in specific cervical cancer cell lines. 1850 74


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