HPV16 E6 regulates the proliferation, invasion, and apoptosis of cervical cancer cells by downregulating miR-504

Background: : A major challenge in cervical cancer radiotherapy is to tailor the radiation doses efficiently to both eliminate malignant cells and to reduce the side effects to normal tissue. Oncolytic adenoviral drug H101 is recently tested and approved for topical adjuvant treatment of several malignancies. Objective: This study is to evaluate the potential neoadjuvant radiotherapy benefits of H101 by testing the inhibitory function of H101 combined with radiation in different cervical cancer cells. Methods: Human cervical cancer cells C33a, SiHa, CaSki, and Hela were treated with varying concentrations of H101 alone or combined with radiation (2Gy or 4Gy). Cell viability and apoptosis were measured at indicated time intervals. HPV16 E6 and cellular p53 mRNA expression alteration were measured by qRT-PCR. RNA scope in-situ detect HPV E6 status. P53 protein alteration are detected by Western blot. Results: Cell viability and apoptosis show the combination of a high dose of H101 (MOI=1000, 10000) with radiation yielded a synergistic anti-cancer effect in all tested cervical cancer cell lines (P<0.05), with the greatest effect achieved in HPV negative C33a cells (P<0.05). Low HPV16 viral load SiHa cell was more sensitive to combination therapy than high HPV16 viral load CaSki cell (P<0.05). The combined treatment could reduce HPV16 E6 expression and increase cellular P53 level compared to radiation alone in SiHa and CaSki (P<0.05). Conclusions: Oncolytic adenoviral H101 effectively enhances the antitumor efficacy of radiation in cervical cancer cells and may serve as a novel combination therapy for cervical cancer.

Download Full-text

Disruption of repressive p130–DREAM complexes by human papillomavirus 16 E6/E7 oncoproteins is required for cell-cycle progression in cervical cancer cells

Journal of General Virology ◽

10.1099/vir.0.035352-0 ◽

2011 ◽

Vol 92 (11) ◽

pp. 2620-2627 ◽

Cited By ~ 28

Author(s):

Nurshamimi Nor Rashid ◽

Rohana Yusof ◽

Roger J. Watson

Keyword(s):

Cell Cycle ◽

Cervical Cancer ◽

Cancer Cells ◽

Cell Cycle Progression ◽

Human Papillomaviruses ◽

G1 Arrest ◽

Cycle Progression ◽

Hpv16 E6 ◽

Cervical Cancer Cells ◽

E6 And E7

Human papillomaviruses (HPVs) with tropism for mucosal epithelia are the major aetiological factors in cervical cancer. Most cancers are associated with so-called high-risk HPV types, in particular HPV16, and constitutive expression of the HPV16 E6 and E7 oncoproteins is critical for malignant transformation in infected keratinocytes. E6 and E7 bind to and inactivate the cellular tumour suppressors p53 and Rb, respectively, thus delaying differentiation and inducing proliferation in suprabasal keratinocytes to enable HPV replication. One member of the Rb family, p130, appears to be a particularly important target for E7 in promoting S-phase entry. Recent evidence indicates that p130 regulates cell-cycle progression as part of a large protein complex termed DREAM. The composition of DREAM is cell cycle-regulated, associating with E2F4 and p130 in G0/G1 and with the B-myb transcription factor in S/G2. In this study, we addressed whether p130–DREAM is disrupted in HPV16-transformed cervical cancer cells and whether this is a critical function for E6/E7. We found that p130–DREAM was greatly diminished in HPV16-transformed cervical carcinoma cells (CaSki and SiHa) compared with control cell lines; however, when E6/E7 expression was targeted by specific small hairpin RNAs, p130–DREAM was reformed and the cell cycle was arrested. We further demonstrated that the profound G1 arrest in E7-depleted CaSki cells was dependent on p130–DREAM reformation by also targeting the expression of the DREAM component Lin-54 and p130. The results show that continued HPV16 E6/E7 expression is necessary in cervical cancer cells to prevent cell-cycle arrest by a repressive p130–DREAM complex.

Download Full-text

Hypomethylated CpG around the transcription start site enables TERT expression and HPV16 E6 regulates TERT methylation in cervical cancer cells

Gynecologic Oncology ◽

10.1016/j.ygyno.2011.11.023 ◽

2012 ◽

Vol 124 (3) ◽

pp. 534-541 ◽

Cited By ~ 21

Author(s):

Jing Jiang ◽

Li-Jun Zhao ◽

Chao Zhao ◽

Guo Zhang ◽

Yun Zhao ◽

...

Keyword(s):

Cervical Cancer ◽

Cancer Cells ◽

Transcription Start Site ◽

Start Site ◽

Transcription Start ◽

Hpv16 E6 ◽

Cervical Cancer Cells ◽

Tert Expression

Download Full-text

Human Papillomavirus Type 16 E6 Induces Self-Ubiquitination of the E6AP Ubiquitin-Protein Ligase

Journal of Virology ◽

10.1128/jvi.74.14.6408-6417.2000 ◽

2000 ◽

Vol 74 (14) ◽

pp. 6408-6417 ◽

Cited By ~ 79

Author(s):

Wynn H. Kao ◽

Sylvie L. Beaudenon ◽

Andrea L. Talis ◽

Jon M. Huibregtse ◽

Peter M. Howley

Keyword(s):

Cervical Cancer ◽

Cancer Cells ◽

Half Life ◽

Mammalian Cells ◽

Human Papillomaviruses ◽

26S Proteasome ◽

Hpv16 E6 ◽

Ubiquitin Protein Ligase ◽

Cervical Cancer Cells

ABSTRACT The E6 protein of the high-risk human papillomaviruses (HPVs) and the cellular ubiquitin-protein ligase E6AP form a complex which causes the ubiquitination and degradation of p53. We show here that HPV16 E6 promotes the ubiquitination and degradation of E6AP itself. The half-life of E6AP is shorter in HPV-positive cervical cancer cells than in HPV-negative cervical cancer cells, and E6AP is stabilized in HPV-positive cancer cells when expression of the viral oncoproteins is repressed. Expression of HPV16 E6 in cells results in a threefold decrease in the half-life of transfected E6AP. E6-mediated degradation of E6AP requires (i) the binding of E6 to E6AP, (ii) the catalytic activity of E6AP, and (iii) activity of the 26S proteasome, suggesting that E6-E6AP interaction results in E6AP self-ubiquitination and degradation. In addition, both in vitro and in vivo experiments indicate that E6AP self-ubiquitination results primarily from an intramolecular transfer of ubiquitin from the active-site cysteine to one or more lysine residues; however, intermolecular transfer can also occur in the context of an E6-mediated E6AP multimer. Finally, we demonstrate that an E6 mutant that is able to immortalize human mammary epithelial cells but is unable to degrade p53 retains its ability to bind and degrade E6AP, raising the possibility that E6-mediated degradation of E6AP contributes to its ability to transform mammalian cells.

Download Full-text