Biomaterial Database

The human papillomavirus 16 E6 protein can either protect or further sensitize cells to TNF: effect of dose. 2005

M Filippova, and T A Brown-Bryan, and C A Casiano, and P J Duerksen-Hughes

Department of Biochemistry and Microbiology, Center for Molecular Biology and Gene Therapy, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA.

High-risk strains of human papillomavirus, including HPV 16, cause human cervical carcinomas, due in part to the activity of their E6 oncogene. E6 interacts with a number of cellular proteins involved in host-initiated apoptotic responses. Paradoxically, literature reports show that E6 can both protect cells from and sensitize cells to tumor necrosis factor (TNF). To examine this apparent contradiction, E6 was transfected into U2OS cells and stable clones were treated with TNF. Intriguingly, clones with a high level of E6 expression displayed an increased sensitivity to TNF by undergoing apoptosis, while those with low expression were resistant. Furthermore, TNF treatment of cells in which the expression of E6 was regulated by the addition of doxycycline demonstrated clearly that while low levels of E6 protect cells from TNF, high levels sensitize cells. Together, these results demonstrate that virus-host interactions can be complex and that both quantitative and qualitative aspects are important in determining outcome.

UI	MeSH Term	Description	Entries
D009856	Oncogene Proteins, Viral	Products of viral oncogenes, most commonly retroviral oncogenes. They usually have transforming and often protein kinase activities.	Viral Oncogene Proteins,Viral Transforming Proteins,v-onc Proteins,Transforming Proteins, Viral,v onc Proteins
D012097	Repressor Proteins	Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.	Repressor Molecules,Transcriptional Silencing Factors,Proteins, Repressor,Silencing Factors, Transcriptional
D004318	Doxycycline	A synthetic tetracycline derivative with similar antimicrobial activity.	2-Naphthacenecarboxamide, 4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-, (4S-(4alpha,4aalpha,5alpha,5aalpha,6alpha,12aalpha))-,Alpha-6-Deoxyoxytetracycline,Atridox,BMY-28689,BU-3839T,Doryx,Doxycycline Calcium,Doxycycline Calcium Salt (1:2),Doxycycline Hemiethanolate,Doxycycline Hyclate,Doxycycline Monohydrate,Doxycycline Monohydrochloride, 6-epimer,Doxycycline Monohydrochloride, Dihydrate,Doxycycline Phosphate (1:1),Doxycycline-Chinoin,Hydramycin,Oracea,Periostat,Vibra-Tabs,Vibramycin,Vibramycin Novum,Vibravenos,Alpha 6 Deoxyoxytetracycline,BMY 28689,BMY28689,BU 3839T,BU3839T,Doxycycline Chinoin,Doxycycline Monohydrochloride, 6 epimer,Vibra Tabs
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D016159	Tumor Suppressor Protein p53	Nuclear phosphoprotein encoded by the p53 gene (GENES, P53) whose normal function is to control CELL PROLIFERATION and APOPTOSIS. A mutant or absent p53 protein has been found in LEUKEMIA; OSTEOSARCOMA; LUNG CANCER; and COLORECTAL CANCER.	p53 Tumor Suppressor Protein,Cellular Tumor Antigen p53,Oncoprotein p53,TP53 Protein,TRP53 Protein,p53 Antigen,pp53 Phosphoprotein,Phosphoprotein, pp53
D017209	Apoptosis	A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, i.e., DNA FRAGMENTATION. It is genetically programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.	Apoptosis, Extrinsic Pathway,Apoptosis, Intrinsic Pathway,Caspase-Dependent Apoptosis,Classic Apoptosis,Classical Apoptosis,Programmed Cell Death,Programmed Cell Death, Type I,Apoptoses, Extrinsic Pathway,Apoptoses, Intrinsic Pathway,Apoptosis, Caspase-Dependent,Apoptosis, Classic,Apoptosis, Classical,Caspase Dependent Apoptosis,Cell Death, Programmed,Classic Apoptoses,Extrinsic Pathway Apoptoses,Extrinsic Pathway Apoptosis,Intrinsic Pathway Apoptoses,Intrinsic Pathway Apoptosis
D045744	Cell Line, Tumor	A cell line derived from cultured tumor cells.	Tumor Cell Line,Cell Lines, Tumor,Line, Tumor Cell,Lines, Tumor Cell,Tumor Cell Lines
D048069	Tumor Necrosis Factors	A family of proteins that were originally identified by their ability to cause NECROSIS of NEOPLASMS. Their necrotic effect on cells is mediated through TUMOR NECROSIS FACTOR RECEPTORS which induce APOPTOSIS.	TNF Receptor Ligands,Tumor Necrosis Factor Superfamily Ligands,Necrosis Factors, Tumor,Receptor Ligands, TNF
D020169	Caspases	A family of intracellular CYSTEINE ENDOPEPTIDASES that play a role in regulating INFLAMMATION and APOPTOSIS. They specifically cleave peptides at a CYSTEINE amino acid that follows an ASPARTIC ACID residue. Caspases are activated by proteolytic cleavage of a precursor form to yield large and small subunits that form the enzyme. Since the cleavage site within precursors matches the specificity of caspases, sequential activation of precursors by activated caspases can occur.	Caspase