High Risk ?-HPV E6 Impairs Translesion Synthesis by Blocking POL? Induction.
Ontology highlight
ABSTRACT:
SUBMITTER: Wendel SO
PROVIDER: S-EPMC7793514 | biostudies-literature | 2020 Dec
REPOSITORIES: biostudies-literature
Publications
High Risk α-HPV E6 Impairs Translesion Synthesis by Blocking POLη Induction.
Wendel Sebastian O SO Snow Jazmine A JA Bastian Tyler T Brown Laura L Hernandez Candy C Burghardt Emily E Kahn Andrew A Murthy Vaibhav V Neill Daniel D Smith Zachary C ZC Ault Kevin K Tawfik Ossama O Wu Cen C Wallace Nicholas A NA
Cancers 20201223 1
High risk genus α human papillomaviruses (α-HPVs) express two versatile oncogenes (α-HPV E6 and E7) that cause cervical cancer (CaCx) by degrading tumor suppressor proteins (p53 and RB). α-HPV E7 also promotes replication stress and alters DNA damage responses (DDR). The translesion synthesis pathway (TLS) mitigates DNA damage by preventing replication stress from causing replication fork collapse. Computational analysis of gene expression in CaCx transcriptomic datasets identified a frequent in ...[more]
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Project description:Many DNA tumor viruses inhibit or repurpose host DNA repair pathways to evade viral defense mechanisms or promote their own replication. High risk genus α human papillomaviruses (α-HPVs) express two versatile oncogenes (α-HPV E6 and E7) that use both approaches simultaneously. To identify new interactions with DNA repair pathways, we conducted a computational analysis of gene expression in cervical cancer (CaCx) transcriptomic datasets and identified a frequent upregulation of translesion synthesis (TLS) genes. TLS polymerase genes, particularly the gene for POLη (POLH), did not follow this pattern. Characterization of α-HPV oncogene expressing cell lines and premalignant cervical tissue confirm these data. They also show that the increased TLS protein abundance come in response to nucleoside depletion. Primary and transformed cell lines to demonstrate that α-HPV E6 blocks POLη induction by degrading p53. Lack of POLη dooms the pathway, preventing it from facilitating tolerance of replication stress. Failed TLS results in replication fork stalling and collapse into deleterious double strand breaks in the DNA (DSBs). Consequently, cellular genome fidelity decreases in a manner consistent with the mutations that accumulate during CaCx progression. Alterations in TLS are determinants for the efficacy of the chemotherapeutics most often used to treat CaCx (cisplatin and carboplatin). Exogenous expression of POLη protected CaCx cells from cisplatin-associated toxicity/damage, effectively stabilizing their genome. TLS polymerase expression is also a prognostic factor in CaCx. Analysis of the cancer genome atlas database (TCGA) shows increased expression of these genes correlated with over a decade shorter median survival.
2020-05-01 | GSE145976 | GEO
Project description:A subset of human papillomaviruses (HPVs) are the cause of virtually every cervical cancer. These so-called "high-risk" HPVs encode two major oncogenes (HPV E6 and E7) that are necessary for transformation. Among "high-risk" HPVs, HPV16 causes most cervical cancers and is often used as a representative model for oncogenic HPVs. The HPV16 E7 oncogene facilitates the HPV16 lifecycle by binding and destabilizing RB, which ensures the virus has access to cellular replication machinery. RB destabilization increases E2F1-responsive gene expression and causes replication stress. While HPV16 E6 mitigates some of the deleterious effects associated with this replication stress by degrading p53, cells undergo separate adaptations to tolerate the stress. Here, we demonstrate that this includes the activation of the translesion synthesis (TLS) pathway, which prevents replication stress from causing replication fork collapse. We show that significantly elevated TLS gene expression is more common in cervical cancers than 15 out of the 16 the other cancer types that we analyzed. In addition to increased TLS protein abundance, HPV16 E7 expressing cells have a reduced ability to induct a critical TLS factor (POLη) in response to replication stress-inducing agents. Finally, we show that increased expression of at least one TLS gene is associated with improved survival for women with cervical cancer.
| S-EPMC9583550 | biostudies-literature
Project description:In eukaryotic cells, the Rad6/Rad18-dependent monoubiquitination of the proliferating cell nuclear antigen (PCNA) plays an essential role in the switching between replication and translesion DNA synthesis (TLS). The DNA polymerase Polη binds to PCNA via a consensus C-terminal PCNA-interacting protein (PIP) motif. It also specifically interacts with monoubiquitinated PCNA thanks to a recently identified ubiquitin-binding domain (UBZ). To investigate whether the TLS activity of Polη is always coupled to PCNA monoubiquitination, we monitor the ability of cell-free extracts to perform DNA synthesis across different types of lesions. We observe that a cis-syn cyclobutane thymine dimer (TT-CPD), but not a N-2-acetylaminofluorene-guanine (G-AAF) adduct, is efficiently bypassed in extracts from Rad18-deficient cells, thus demonstrating the existence of a Polη-dependent and Rad18-independent TLS pathway. In addition, by complementing Polη-deficient cells with PIP and UBZ mutants, we show that each of these domains contributes to Polη activity. The finding that the bypass of a CPD lesion in vitro does not require Ub-PCNA but nevertheless depends on the UBZ domain of Polη, reveals that this domain may play a novel role in the TLS process that is not related to the monoubiquitination status of PCNA.
| S-EPMC2965212 | biostudies-literature
Project description:The E6 oncoprotein from high-risk genus alpha human papillomaviruses (α-HPVs), such as HPV 16, has been well characterized with respect to the host-cell proteins it interacts with and corresponding signaling pathways that are disrupted due to these interactions. Less is known regarding the interacting partners of E6 from the genus beta papillomaviruses (β-HPVs); however, it is generally thought that β-HPV E6 proteins do not interact with many of the proteins known to bind to α-HPV E6. Here we identify p300 as a protein that interacts directly with E6 from both α- and β-HPV types. Importantly, this association appears much stronger with β-HPV types 5 and 8-E6 than with α-HPV type 16-E6 or β-HPV type 38-E6. We demonstrate that the enhanced association between 5/8-E6 and p300 leads to p300 degradation in a proteasomal-dependent but E6AP-independent manner. Rather, 5/8-E6 inhibit the association of AKT with p300, an event necessary to ensure p300 stability within the cell. Finally, we demonstrate that the decreased p300 protein levels concomitantly affect downstream signaling events, such as the expression of differentiation markers K1, K10 and Involucrin. Together, these results demonstrate a unique way in which β-HPV E6 proteins are able to affect host-cell signaling in a manner distinct from that of the α-HPVs.
| S-EPMC3161984 | biostudies-literature
Project description:High-risk human papillomavirus (HPV)-positive head and neck squamous cell carcinomas (HNSCCs) are highly invasive; however the identity of downstream effectors responsible for their aggressive phenotype remains underinvestigated. Here, we report that HPV-mediated up-regulation of heparanase enzyme can provide mechanistic explanation for augmented invasiveness of HPV-positive HNSCCs. Heparanase is the sole mammalian enzyme (endo-β-d-glucuronidase) degrading heparan sulphate glycosaminoglycan, key polysaccharide of the extracellular matrix. Cleavage of heparan sulphate by heparanase leads to disassembly of extracellular barriers, enabling local invasion and metastatic spread of the tumour, and releases heparan sulphate-bound growth factors from the extracellular depots. Heparanase is tightly implicated in head and neck cancer progression; yet, molecular mechanisms underlying transcriptional activation of the heparanase gene in HNSCC are largely unknown. We found that HPV16 oncogene E6 is capable of inducing overexpression of heparanase in HNSCC. Notably, radiation treatment dose-dependently suppresses E6-induced heparanase expression in vitro. Our results provide the first evidence for a functional involvement of HPV in heparanase induction in head and neck tumourigenesis and, given ongoing clinical testing of several heparanase-inhibiting compounds, offer important avenue for future therapeutic exploration in HNSCC, as well as other HPV-associated malignancies (i.e. cervical carcinoma).
| S-EPMC3916129 | biostudies-literature
Project description:Every year, approximately 470,000 new cases of cervical cancer are diagnosed and approximately 230,000 women worldwide die of the disease, with the majority (approximately 80%) of these cases and deaths occurring in developing countries. Human papillomaviruses (HPVs) are the etiological agents in nearly all cases (99.7%) of cervical cancer, and the HPV E6 protein is one of two viral oncoproteins that is expressed in virtually all HPV-positive cancers. E6 hijacks a cellular ubiquitin ligase, E6AP, resulting in the ubiquitylation and degradation of the p53 tumor suppressor, as well as several other cellular proteins. While the recent introduction of prophylactic vaccines against specific HPV types offers great promise for prevention of cervical cancer, there remains a need for therapeutics. Biochemical characterization of E6 and E6AP has suggested approaches for interfering with the activities of these proteins that could be useful for this purpose. PUBLICATION HISTORY : Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).
| S-EPMC2582798 | biostudies-literature
Project description:The human papillomavirus (HPV) HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6.
| S-EPMC4767726 | biostudies-literature
Project description:All living organisms are continually exposed to agents that damage their DNA, which threatens the integrity of their genome. As a consequence, cells are equipped with a plethora of DNA repair enzymes to remove the damaged DNA. Unfortunately, situations nevertheless arise where lesions persist, and these lesions block the progression of the cell's replicase. In these situations, cells are forced to choose between recombination-mediated "damage avoidance" pathways or a specialized DNA polymerase (pol) to traverse the blocking lesion. The latter process is referred to as Translesion DNA Synthesis (TLS). As inferred by its name, TLS not only results in bases being (mis)incorporated opposite DNA lesions but also bases being (mis)incorporated downstream of the replicase-blocking lesion, so as to ensure continued genome duplication and cell survival. Escherichia coli and Salmonella typhimurium possess five DNA polymerases, and while all have been shown to facilitate TLS under certain experimental conditions, it is clear that the LexA-regulated and damage-inducible pols II, IV, and V perform the vast majority of TLS under physiological conditions. Pol V can traverse a wide range of DNA lesions and performs the bulk of mutagenic TLS, whereas pol II and pol IV appear to be more specialized TLS polymerases.
| S-EPMC4231548 | biostudies-literature
Project description:Background:
The National Cancer Institute (NCI) Surgery Branch has developed an experimental therapy for treating patients with cancer that involves taking white blood cells from the patient, growing them in the laboratory in large numbers, genetically modifying these specific cells with a type of virus (retrovirus) to attack only the tumor cells, and then giving the cells back to the patient. This type of therapy is called gene transfer. Researchers want to test this on human papilloma virus (HPV)-associated cancers.
Objective:
- The purpose of this study is to determine a safe number of these cells to infuse and to see if these particular tumor-fighting cells (Anti-HPV E6) can shrink tumors associated with HPV and test the toxicity of this treatment.
Eligibility:
- Adults age 18-66 with an HPV-16-associated cancer.
Design:
* Work up stage: Patients will be seen as an outpatient at the National Institutes of Health (NIH) clinical Center and undergo a history and physical examination, scans, x-rays, lab tests, and other tests as needed
* Leukapheresis: If the patients meet all of the requirements for the study they will undergo leukapheresis to obtain white blood cells to make the anti HPV E6 cells. {Leukapheresis is a common procedure, which removes only the white blood cells from the patient.}
* Treatment: Once their cells have grown, the patients will be admitted to the hospital for the conditioning chemotherapy, the anti HPV E6 cells and aldesleukin. They will stay in the hospital for about 4 weeks for the treatment.
Follow up: Patients will return to the clinic for a physical exam, review of side effects, lab tests, and scans about every 1-3 months for the first year, and then every 6 months to 1 year as long as their tumors are shrinking. Follow up visits take up to 2 days.
| 2177506 | ecrin-mdr-crc
Project description:PurposeHigh-risk human papillomaviruses (HR HPV) cause cervical cancer, and in these cancers, HPV type 16 is the most common HR type. The HR viral oncogenes E6 and E7 partner with cellular proteins to drive cancer and modulate immune pathways; previously, we demonstrated in keratinocytes that HPV 16 E6 and high expression of the endogenous host protein partner NFX1-123 led to the increased expression of multiple genes, including Notch1, secretory leukocyte peptidase inhibitor (SLPI), and retinoic acid early transcript 1G (RAET1G). The present study was conducted to determine if NFX1-123 was highly expressed in cervical cancer and if genes increased by NFX1-123 and 16E6 in keratinocytes were also increased in cervical cancers.Materials and methodsThe Cancer Genome Atlas (TCGA) database and The Human Protein Atlas database were used to compare relative mRNA and protein gene expression, respectively, in the normal cervix and cervical cancers. Formalin-fixed paraffin-embedded (FFPE) normal cervix and HPV 16 positive cervical cancer samples were analyzed for relative protein expression by immunohistochemical staining. Protein expression of a subset of regulated genes was quantified by Western blot of HPV positive and negative cell lines.ResultsImmunohistochemical staining of HPV 16 positive cervical dysplasias and cancers revealed high NFX1-123, Ki67, and Notch1 expression. NFX1 and NFX1L1 mRNA levels were increased in cervical cancers compared to normal cervix in the TCGA database. Fourteen genes previously identified as upregulated in keratinocytes with 16E6 and overexpressed NFX1-123 also had high mRNA expression and selected genes had high protein expression in cervical cancers and cell lines.ConclusionIn cervical cancer, NFX1-123 is highly expressed, and 16E6 and NFX1-123 together alter the expression of a wide set of genes. The involvement of these genes in cell proliferation, differentiation, invasion, and metastasis provides further insight into potential ways that HR HPVs promote cancer initiation and maintenance.
| S-EPMC7326398 | biostudies-literature