The Major Constituent of Green Tea, Epigallocatechin-3-Gallate (EGCG), Inhibits the Growth of HPV18-Infected Keratinocytes by Stimulating Proteasomal Turnover of the E6 and E7 Oncoproteins

Epigallocatechin-3-gallate (EGCG), the primary bioactive polyphenol in green tea, has been shown to inhibit the growth of human papilloma virus (HPV)-transformed keratinocytes. Here, we set out to examine the consequences of EGCG treatment on the growth of HPV18-immortalised foreskin keratinocytes (HFK-HPV18) and an authentic HPV18-positive vulvar intraepithelial neoplasia (VIN) clone, focusing on its ability to influence cell proliferation and differentiation and to impact on viral oncogene expression and virus replication. EGCG treatment was associated with degradation of the E6 and E7 oncoproteins and an upregulation of their associated tumour suppressor genes; consequently, keratinocyte proliferation was inhibited in both monolayer and organotypic raft culture. While EGCG exerted a profound effect on cell proliferation, it had little impact on keratinocyte differentiation. Expression of the late viral protein E4 was suppressed in the presence of EGCG, suggesting that EGCG was able to block productive viral replication in differentiating keratinocytes. Although EGCG did not alter the levels of E6 and E7 mRNA, it enhanced the turnover of the E6 and E7 proteins. The addition of MG132, a proteasome inhibitor, to EGCG-treated keratinocytes led to the accumulation of the E6/E7 proteins, showing that EGCG acts as an anti-viral, targeting the E6 and E7 proteins for proteasome-mediated degradation.

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Identification of Unusual E6 and E7 Proteins within Avian Papillomaviruses: Cellular Localization, Biophysical Characterization, and Phylogenetic Analysis

Journal of Virology ◽

10.1128/jvi.01777-08 ◽

2009 ◽

Vol 83 (17) ◽

pp. 8759-8770 ◽

Cited By ~ 26

Author(s):

Koenraad Van Doorslaer ◽

Abdellahi Ould M'hamed Ould Sidi ◽

Katia Zanier ◽

Vladimir Rybin ◽

François Deryckère ◽

...

Keyword(s):

Cell Proliferation ◽

Cellular Localization ◽

Binding Domain ◽

Single Domain ◽

Zinc Binding ◽

Resonance Spectroscopy ◽

E6 And E7 ◽

E7 Proteins ◽

Zinc Binding Domain ◽

Terminal Domains

ABSTRACT Papillomaviruses (PVs) are a large family of small DNA viruses infecting mammals, reptiles, and birds. PV infection induces cell proliferation that may lead to the formation of orogenital or skin tumors. PV-induced cell proliferation has been related mainly to the expression of two small oncoproteins, E6 and E7. In mammalian PVs, E6 contains two 70-residue zinc-binding repeats, whereas E7 consists of a natively unfolded N-terminal region followed by a zinc-binding domain which folds as an obligate homodimer. Here, we show that both the novel francolin bird PV Francolinus leucoscepus PV type 1 (FlPV-1) and the chaffinch bird PV Fringilla coelebs PV contain unusual E6 and E7 proteins. The avian E7 proteins contain an extended unfolded N terminus and a zinc-binding domain of reduced size, whereas the avian E6 proteins consist of a single zinc-binding domain. A comparable single-domain E6 protein may have existed in a common ancestor of mammalian and avian PVs. Mammalian E6 C-terminal domains are phylogenetically related to those of single-domain avian E6, whereas mammalian E6 N-terminal domains seem to have emerged by duplication and subsequently diverged from the original ancestral domain. In avian and mammalian cells, both FlPV-1 E6 and FlPV-1 E7 were evenly expressed in the cytoplasm and the nucleus. Finally, samples of full-length FlPV-1 E6 and the FlPV-1 E7 C-terminal zinc-binding domain were prepared for biophysical analysis. Both constructs were highly soluble and well folded, according to nuclear magnetic resonance spectroscopy measurements.

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Individual and Complementary Effects of Human Papillomavirus Oncogenes on Epithelial Cell Proliferation and Differentiation

Cells Tissues Organs ◽

10.1159/000441716 ◽

2015 ◽

Vol 201 (2) ◽

pp. 97-108 ◽

Cited By ~ 5

Author(s):

Sven Bergner ◽

Gordana Halec ◽

Markus Schmitt ◽

François Aubin ◽

Angel Alonso ◽

...

Keyword(s):

Cell Proliferation ◽

Human Papillomavirus ◽

Three Dimensional ◽

Morphological Characteristics ◽

Intraepithelial Neoplasia ◽

Vector System ◽

Proliferation Markers ◽

Raft Culture ◽

E6 And E7 ◽

Differentiation And Proliferation

Previous studies on human papillomavirus (HPV) type 16 protein functions have established the oncogenic nature of three viral proteins: E5, E6 and E7. Here we have studied the functions of these proteins by functional deletion of the individual E5, E6 or E7, or both E6 and E7 oncogenes in the context of the whole viral genome. These mutants, or the intact wild-type genome, were expressed from the natural viral promoters along with differentiation of epithelial HaCaT cells in three-dimensional collagen raft cultures. High episomal viral copy numbers were obtained using a transfection-based loxp-HPV16-eGFP-N1 vector system. All epithelial equivalents carrying the different HPV type 16 genomes showed pronounced hyperplastic and dysplastic morphology. Particularly the E7 oncogene, with contribution of E6, was shown to enhance cell proliferation. Specifically, the crucial role of E7 in HPV-associated hyperproliferation was clearly manifested. Based on morphological characteristics, immunohistochemical staining for differentiation and proliferation markers, and low expression of E1^E4, we propose that our raft culture models produce cervical intraepithelial neoplasia (CIN)1 and CIN2-like tissue. Our experimental setting provides an alternative tool to study concerted functions of HPV proteins in the development of epithelial dysplasia.

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Therapeutic Potential of EGCG, a Green Tea Polyphenol, for Treatment of Coronavirus Diseases

Life ◽

10.3390/life11030197 ◽

2021 ◽

Vol 11 (3) ◽

pp. 197

Author(s):

Junsoo Park ◽

Rackhyun Park ◽

Minsu Jang ◽

Yea-In Park

Keyword(s):

Green Tea ◽

Therapeutic Potential ◽

Epigallocatechin Gallate ◽

Major Constituent ◽

Future Research ◽

Tea Polyphenol ◽

Egcg Treatment ◽

Main Protease ◽

Green Tea Polyphenol ◽

3Cl Protease

Epigallocatechin gallate (EGCG) is a major catechin found in green tea, and there is mounting evidence that EGCG is potentially useful for the treatment of coronavirus diseases, including coronavirus disease 2019 (COVID-19). Coronaviruses encode polyproteins that are cleaved by 3CL protease (the main protease) for maturation. Therefore, 3CL protease is regarded as the main target of antivirals against coronaviruses. EGCG is a major constituent of brewed green tea, and several studies have reported that EGCG inhibits the enzymatic activity of the coronavirus 3CL protease. Moreover, EGCG has been reported to regulate other potential targets, such as RNA-dependent RNA polymerase and the viral spike protein. Finally, recent studies have demonstrated that EGCG treatment interferes with the replication of coronavirus. In addition, the bioavailability of EGCG and future research prospects are discussed.

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Papillomavirus E7 Oncoproteins Share Functions with Polyomavirus Small T Antigens

Journal of Virology ◽

10.1128/jvi.03282-14 ◽

2014 ◽

Vol 89 (5) ◽

pp. 2857-2865 ◽

Cited By ~ 11

Author(s):

Elizabeth A. White ◽

Rebecca E. Kramer ◽

Justin H. Hwang ◽

Arun T. Pores Fernando ◽

Nana Naetar ◽

...

Keyword(s):

T Antigen ◽

Human Papillomaviruses ◽

T Antigens ◽

Tumor Viruses ◽

Murine Polyomavirus ◽

Cellular Pathways ◽

E6 And E7 Oncoproteins ◽

E6 And E7 ◽

Transforming Proteins ◽

E7 Proteins

ABSTRACTMany of the small DNA tumor viruses encode transforming proteins that function by targeting critical cellular pathways involved in cell proliferation and survival. In this study, we have examined whether some of the functions of the polyomavirus small T antigens (ST) are shared by the E6 and E7 oncoproteins of two oncogenic papillomaviruses. Using three different assays, we have found that E7 can provide some simian virus 40 (SV40) or murine polyomavirus (PyV) ST functions. Both human papillomavirus 16 (HPV16) and bovine papillomavirus (BPV1) E7 proteins are capable of partially substituting for SV40 ST in a transformation assay that also includes SV40 large T antigen, the catalytic subunit of cellular telomerase, and oncogenic Ras. Like SV40 ST, HPV16 E7 has the ability to override a quiescence block induced by mitogen deprivation. Like PyV ST, it also has the ability to inhibit myoblast differentiation. At least two of these activities are dependent upon the interaction of HPV16 E7 with retinoblastoma protein family members. For small T antigens, interaction with PP2A is needed for each of these functions. Even though there is no strong evidence that E6 or E7 share the ability of small T to interact with PP2A, E7 provides these functions related to cellular transformation.IMPORTANCEDNA tumor viruses have provided major insights into how cancers develop. Some viruses, like the human papillomaviruses, can cause cancer directly. Both the papillomaviruses and the polyomaviruses have served as tools for understanding pathways that are often perturbed in cancer. Here, we have compared the functions of transforming proteins from several DNA tumor viruses, including two papillomaviruses and two polyomaviruses. We tested the papillomavirus E6 and E7 oncoproteins in three functional assays and found that E7 can provide some or all of the functions of the SV40 small T antigen, another well-characterized oncoprotein, in two of these assays. In a third assay, papillomavirus E7 has the same effect as the murine polyomavirus small T protein. In summary, we report several new functions for the papillomavirus E7 proteins, which will contribute new insights into the roles of viruses in cancer and the cellular pathways they perturb in carcinogenesis.

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Epigallocatechin-3-Gallate (EGCG), an Active Compound of Green Tea Attenuates Acute Lung Injury Regulating Macrophage Polarization and Krüpple-Like-Factor 4 (KLF4) Expression

Molecules ◽

10.3390/molecules25122853 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2853 ◽

Cited By ~ 2

Author(s):

Saleh A. Almatroodi ◽

Ahmad Almatroudi ◽

Mohammed A. Alsahli ◽

Mohammad A. Aljasir ◽

Mansoor Ali Syed ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Oxidative Damage ◽

Green Tea ◽

Macrophage Polarization ◽

Major Constituent ◽

Total Leucocyte Count ◽

Protective Effects ◽

Egcg Treatment ◽

Macrophage Polarisation

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are serious clinical complications with a high frequency of morbidity and mortality. The initiation and amplification of inflammation is a well-known aspect in the pathogenesis of ALI and related disorders. Therefore, inhibition of the inflammatory mediators could be an ideal approach to prevent ALI. Epigallocatechin-3-gallate (EGCG), a major constituent of green tea, has been shown to have protective effects on oxidative damage and anti-inflammation. The goal of the present study was to determine whether EGCG improves phenotype and macrophage polarisation in LPS-induced ALI. C57BL/6 mice were given two doses of EGCG (15 mg/kg) intraperitoneally (IP) 1 h before and 3 h after LPS instillation (2 mg/kg). EGCG treatment improved histopathological lesions, Total Leucocyte count (TLC), neutrophils infiltration, wet/dry ratio, total proteins and myeloperoxidase (MPO) activity in LPS-induced lung injury. The results displayed that EGCG reduced LPS-induced ALI as it modulates macrophage polarisation towards M2 status. Furthermore, EGCG also reduced the expression of proinflammatory M1 mediators iNOS TNF-α, IL-1β and IL-6 in the LPS administered lung microenvironment. In addition, it increased the expression of KLF4, Arg1 and ym1, known to augment the M2 phenotype of macrophages. EGCG also alleviated the expression of 8-OHdG, nitrotyrosine, showing its ability to inhibit oxidative damage. TREM1 in the lung tissue and improved lung regenerative capacity by enhancing Ki67, PCNA and Ang-1 protein expression. Together, these results proposed the protective properties of EGCG against LPS-induced ALI in may be attributed to the suppression of M1/M2 macrophages subtype ratio, KLF4 augmentation, lung cell regeneration and regulating oxidative damage in the LPS-induced murine ALI.

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Global Effects of Human Papillomavirus Type 18 E6/E7 in an Organotypic Keratinocyte Culture System

Journal of Virology ◽

10.1128/jvi.78.17.9041-9050.2004 ◽

2004 ◽

Vol 78 (17) ◽

pp. 9041-9050 ◽

Cited By ~ 43

Author(s):

Peggy A. Garner-Hamrick ◽

J. M. Fostel ◽

Wei-Ming Chien ◽

N. Sanjib Banerjee ◽

Louise T. Chow ◽

...

Keyword(s):

Human Papillomavirus ◽

Culture System ◽

Human Keratinocytes ◽

Protein Translation ◽

Primary Human Keratinocytes ◽

Raft Culture ◽

Dna And Rna ◽

E6 And E7 ◽

E7 Proteins ◽

Hpv 18

ABSTRACT The effects of human papillomavirus type 18 (HPV-18) E6 and E7 proteins on global patterns of host gene expression in primary human keratinocytes grown in organotypic raft culture system were assessed. Primary human keratinocytes were infected with retroviruses that express the wild-type HPV-18 E6 and E7 genes from the native differentiation-dependent HPV enhancer-promoter. Total RNA was isolated from raft cultures and used to generate probes for querying Affymetrix U95A microarrays, which contain >12,500 human gene sequences. Quadruplicate arrays of each E6/E7-transduced and empty vector-transduced samples were analyzed by 16 pairwise comparisons. Transcripts altered in ≥12 comparisons were selected for further analysis. With this approach, HPV-18 E6/E7 expression significantly altered the expression of 1,381 genes. A large increase in transcripts associated with DNA and RNA metabolism was observed, with major increases noted for transcription factors, splicing factors, and DNA replication elements, among others. Multiple genes associated with protein translation were downregulated. In addition, major alterations were found in transcripts associated with the cell cycle and cell differentiation. Our study provides a systematic description of transcript changes brought about by HPV-18 E6/E7 in a physiologically relevant model and should furnish a solid source of information to guide future studies.

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Epitome mapping of E6 and E7 proteins from high-risk oncogenic HPV types 16, 18 and 45

10.21203/rs.2.24484/v1 ◽

2020 ◽

Author(s):

Wan-Xiang Xu ◽

Hai-Ping Tang ◽

Jian Wang ◽

Jian-Min Zhan ◽

Wen-Bo Lian ◽

...

Keyword(s):

Cervical Cancer ◽

High Risk ◽

Sequence Alignment ◽

Cell Epitope ◽

Homologous Proteins ◽

B Cell Epitope ◽

Hpv Types ◽

E6 And E7 Oncoproteins ◽

E6 And E7 ◽

E7 Proteins

Abstract Background It is crucial to reveal entire epitomes of more target homologous proteins and specificity of each mapped B cell epitope (BCE) within them for the development of high-risk (hr-) human papillomavirus (HPV) type-specific diagnostic reagents. Methods Recombinant E6 and -E7 oncoproteins from HPV16/18/45 were immunized mice to prepare Rabbit antisera. Overlapping 16mer/8mer-peptides for two rounds of antigenic peptide and fine BCE motif mapping were expressed as GST188 fusion proteins. Fine BCEs were delineated by Western blot and sequence alignment. Results In this work, we decoded six epitomes of E6 and E7 oncoproteins from three HPV types 16, 18 and 45 that are the most common hr-HPVs in cervical cancer patients worldwide, in which total 35 fine BCEs (8, 6 and 4 for E6; 7, 6 and 4 for E7) were mapped using rabbit antisera to respective recombinant proteins. The specificity of each mapped BCE among 20 defined or possible hr-HPVs was delineated by sequence alignment based on BCE minimal motif. According to similarities of immune responses to E6/E7 existed among rabbit and humans, 7 human-recognizing (HR) BCE motifs in HR-peptides of HPV16/18-E6 and E7 proteins were delimitated by comparing with corresponding rabbit-recognizing BCEs. Also, the unique BCE distribution within three delineated E7 epitomes was confirmed, in which almost mapped BCEs were clustered at the first half of the molecules, suggesting that it may be a common characteristic of hr-HPV E7 proteins. Conclusions The results would form the basis for identifying HR-BCEs and developing serodiagnostic reagents used in HPV-based cervical cancer screening and HPV-positive women managing.

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E6 and E7 oncoproteins: Potential targets of cervical cancer

Current Medicinal Chemistry ◽

10.2174/0929867327666201111145546 ◽

2020 ◽

Vol 27 ◽

Author(s):

Ramarao Malla ◽

Mohammad Amjad Kamal

Keyword(s):

Cervical Cancer ◽

Drug Resistance ◽

Host Cell ◽

Molecular Mechanisms ◽

Immune Therapy ◽

Cervical Lesions ◽

Diagnostic Strategies ◽

E6 And E7 Oncoproteins ◽

E6 And E7

: Cervical cancer (CC) is the fourth leading cancer in women in the age group 15-44 globally. Experimental as well as epidemiological studies identified that type16 and 18 HPV cause 70% of precancerous cervical lesions as well as cervical cancer worldwide by bringing about genetic as well as epigenetic changes in the host genome. The insertion of the HPV genome triggers various defense mechanisms including the silencing of tumor suppressor genes as well as activation of oncogenes associated with cancer metastatic pathway. E6 and E7 are small oncoproteins consisting of 150 and 100 amino acids respectively. These oncoproteins affect the regulation of the host cell cycle by interfering with p53 and pRb. Further these oncoproteins adversely affect the normal functions of the host cell by binding to their signaling proteins. Recent studies demonstrated that E6 and E7 oncoproteins are potential targets for CC. Therefore, this review discusses the role of E6 and E7 oncoproteins in metastasis and drug resistance as well as their regulation, early oncogene mediated signaling pathways. This review also uncovers the recent updates on molecular mechanisms of E6 and E7 mediated phytotherapy, gene therapy, immune therapy, and vaccine strategies as well as diagnosis through precision testing. Therefore, understanding the potential role of E6/E7 in metastasis and drug resistance along with targeted treatment, vaccine, and precision diagnostic strategies could be useful for the prevention and treatment of cervical cancer.

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Versatile Health Benefits of Catechin from Green Tea (Camellia sinensis)

Current Nutrition & Food Science ◽

10.2174/1573401313666171003150503 ◽

2019 ◽

Vol 15 (1) ◽

pp. 3-10 ◽

Cited By ~ 4

Author(s):

Satheesh Babu Natarajan ◽

Suriyakala Perumal Chandran ◽

Sahar Husain Khan ◽

Packiyaraj Natarajan ◽

Karthiyaraj Rengarajan

Keyword(s):

Green Tea ◽

Camellia Sinensis ◽

Health Benefits ◽

Epigallocatechin Gallate ◽

Extraction Methods ◽

Major Constituent ◽

Epicatechin Gallate ◽

Wide Range ◽

Green Tea Catechin ◽

Anti Inflammatory

Background: Tea (Camellia sinensis, Theaceae) is the second most consumed beverage in the world. Green tea is the least processed and thus contain rich antioxidant level, and believed to have most of the health benefits. Methods: We commenced to search bibliographic collection of peer reviewed research articles and review articles to meet the objective of this study. Results: From this study, we found that the tea beverage contains catechins are believed to have a wide range of health benefits which includes neuroprotective, anti-inflammatory, antiulcer, antiviral, antibacterial, and anti-parasitic effects. The four major catechin compounds of green tea are epigallocatechin (EGC), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG), of which EGCG is the major constituent and representing 50-80% of the total catechin content. And also contain xanthine derivatives such as caffeine, theophylline, and theobromine, and the glutamide derivative theanine. It also contains many nutritional components, such as vitamin E, vitamin C, fluoride, and potassium. We sum up the various green tea phytoconstituents, extraction methods, and its medicinal applications. Conclusion: In this review article, we have summarized the pharmacological importance of green tea catechin which includes antioxidant potential, anti-inflammatory, antimicrobial, anticancer, antidiabetic and cosmetic application.

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