The high-risk HPV E6 target scribble (hScrib) is required for HPV E6 expression in cervical tumour-derived cell lines

ABSTRACT Human papillomavirus (HPV) E6 oncoprotein targets certain tumor suppressors such as MAGI-1 and SAP97/hDlg for degradation. A short peptide at the C terminus of E6 interacts specifically with the PDZ domains of these tumor suppressors, which is a property unique to high-risk HPVs that are associated with cervical cancer. The detailed recognition mechanisms between HPV E6 and PDZ proteins are unclear. To understand the specific binding of cellular PDZ substrates by HPV E6, we have solved the crystal structures of the complexes containing a peptide from HPV18 E6 bound to three PDZ domains from MAGI-1 and SAP97/Dlg. The complex crystal structures reveal novel features of PDZ peptide recognition that explain why high-risk HPV E6 can specifically target these cellular tumor suppressors for destruction. Moreover, a new peptide-binding loop on these PDZs is identified as interacting with the E6 peptide. Furthermore, we have identified an arginine residue, unique to high-risk HPV E6 but outside the canonical core PDZ recognition motif, that plays an important role in the binding of the PDZs of both MAGI-I and SAP97/Dlg, the mutation of which abolishes E6's ability to degrade the two proteins. Finally, we have identified a dimer form of MAGI-1 PDZ domain 1 in the cocrystal structure with E6 peptide, which may have functional relevance for MAGI-1 activity. In addition to its novel insights into the biochemistry of PDZ interactions, this study is important for understanding HPV-induced oncogenesis; this could provide a basis for developing antiviral and anticancer compounds.

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Up-regulation of peroxiredoxin 3 by high-risk human papillomavirus in cervical cancer cells

Archives of Medical Science ◽

10.5114/aoms/125932 ◽

2021 ◽

Author(s):

Hou-Li Liu ◽

Xiao-Juan Sun ◽

Xiaoyan Li ◽

Jingmin Li ◽

Xianyong Bai ◽

...

Keyword(s):

Oxidative Stress ◽

Cervical Cancer ◽

Human Papillomavirus ◽

High Risk ◽

Cancer Cells ◽

Cell Lines ◽

Cervical Cancer Cells ◽

Cancer Tissues ◽

High Risk Hpv ◽

Peroxiredoxin 3

IntroductionPeroxiredoxin 3 (PRX3) is a member of PRX family with antioxidant functions by scavenging hydrogen peroxide. Since the development of cervical cancer is causally linked to high-risk human papillomavirus (HPV) that induces oxidative stress, we conducted the present study to investigate the response of PRX3 to high-risk HPV infection.Material and methodsThis study included fifty-six patients with invasive squamous cervical cancer and sixty control patients with hysteromyoma. Enzyme-linked immunosorbent assay was performed to detect cervical oxidative stress and serum PRX3. The expression of PRX3 and oncoprotein E6 of HPV16 or HPV18 was examined in cervical cancer tissues by immunohistochemistry. Western Blot was applied to detect the expression of PRX3 and E6 in cervical cancer cell lines including CaSki, HeLa, and C33A.ResultsPatients with cervical cancer showed higher serum PRX3 than control patients with hysteromyoma. Levels of oxidative markers in cervical cancer tissues were elevated as compared to normal cervical epithelia. PRX3 expression was upregulated in cervical cancer tissues and the upregulation was positively associated with the expression of E6 of HPV16 or HPV18. The association was confirmed in HPV-containing cervical cancer cell lines including CaSki and HeLa.ConclusionsOur results indicated a positive response of PRX3 to HPV-induced oxidative stress. Serum PRX3 might be a potential indicator of active amplification of high-risk HPV in cervical cancer cells.

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HPVE6-USP46 Mediated Cdt2 Stabilization Reduces Set8 Mediated H4K20-Methylation to Induce Gene Expression Changes

Cancers ◽

10.3390/cancers14010030 ◽

2021 ◽

Vol 14 (1) ◽

pp. 30

Author(s):

Shashi Kiran ◽

Briana Wilson ◽

Shekhar Saha ◽

Julia Ann Graff ◽

Anindya Dutta

Keyword(s):

Gene Expression ◽

Amino Acid ◽

High Risk ◽

Cell Lines ◽

Deletion Mapping ◽

Helix Loop Helix ◽

Induced Tumors ◽

Transformed Cell Lines ◽

High Risk Hpv

E6 from high-risk strains of HPV is well known to transform cells by deregulating p53. We reported that in HPV transformed cell-lines E6 from high-risk HPV can recruit the USP46 deubiquitinase to substrates such as Cdt2 and stabilize the latter, and that USP46 is important for growth of HPV induced tumors in xenografts. Here we show that in cervical cancer biopsies the stabilization of Cdt2 in the HPV-induced cancers leads to the decrease of a CRL4-Cdt2 substrate, the histone H4K20 mono-methyltransferase Set8, and decrease in H4K20me1 or H4K20me3 that can be detected by immunohistochemistry. In HPV-transformed cancer cell lines in vitro, knockdown of E6 decreases Cdt2 and increases Set8. Co-knockdown of Set8 shows that some of the gene expression changes produced by E6 knockdown is due to the increase of Set8. EGFR and EGFR regulated genes were identified in this set of genes. Turning to the mechanism by which E6 stabilizes Cdt2, we find that a purified E6:USP46 complex has significantly more de-ubiquitinase activity in vitro than USP46 alone, demonstrating that E6 can directly interact with USP46 in the absence of other proteins and that it can substitute for the known activators of USP46, UAF1 and WDR20. Deletion mapping of Cdt2 shows that there are three discrete, but redundant, parts of the substrate that are essential for stabilization by E6: USP46. The helix–loop–helix region or the WD40 repeat driven beta-propeller structure of Cdt2 are dispensable for the stabilization implying that interaction with DDB1 (and the rest of the CRL4 complex) or with the substrate of the CRL4-Cdt2 E3 ligase is not necessary for E6:USP46 to interact with and stabilize Cdt2. The identification of 50 amino acid stretches in the 731 amino acid Cdt2 protein as being important for the stabilization by E6 underlines the specificity of the process. In summary, E6 activates the deubiquitinase activity of USP46, stabilizes Cdt2 utilizing multiple sites on Cdt2, and leads to degradation of Set8 and changes in gene-expression in HPV-transformed cells.

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Oncoproteins of High-Risk HPV and EBV Cooperate to Enhance Cell Motility and Invasion of Human Breast Cancer Cells via Erk1/Erk2 and β-Catenin Signaling Pathways

Frontiers in Oncology ◽

10.3389/fonc.2021.630408 ◽

2021 ◽

Vol 11 ◽

Author(s):

Ishita Gupta ◽

Ayesha Jabeen ◽

Semir Vranic ◽

Ala-Eddin Al Moustafa ◽

Hamda Al-Thawadi

Keyword(s):

Breast Cancer ◽

High Risk ◽

Cell Motility ◽

Cell Lines ◽

Cancer Cell ◽

Breast Cancer Cell ◽

Human Breast Cancer ◽

Breast Cancer Cell Lines ◽

Human Breast ◽

High Risk Hpv

Breast cancer is a leading cause of death in women around the world. Most breast cancer-related deaths are a result of complications from the metastatic spread. Several recent studies reported that high-risk human papillomaviruses (HPVs) and Epstein–Barr virus (EBV) are co-presented in different types of human carcinomas including breast; however, the cooperative effects between high-risk HPVs and EBV oncoproteins in human breast cancer have not been investigated yet. Thus, we herein explored the cooperation outcome between E6/E7 and latent membrane protein 1 (LMP1) oncoproteins of high-risk HPV type 16 and EBV, respectively, in two human breast cancer cell lines, MCF7 and MDA-MB-231. Our data revealed that the cooperation of E6/E7 and LMP1 oncoproteins stimulates cell proliferation and deregulates cell cycle progression of human breast cancer and normal mammary cells; in parallel, we noted that E6/E7/LMP1 incite colony formation of both breast cancer cell lines but not normal cells. More significantly, our results point out that the co-expression of E6/E7 and LMP1 oncoproteins enhances cell motility and invasion of MCF7 and MDA-MB-231 cell lines; this is accompanied by deregulation of epithelial–mesenchymal transition biomarkers including E-cadherin, β-catenin, fascin, and vimentin. The molecular pathway analysis of HPV and EBV oncoproteins cooperation shows that it can enhance the phosphorylation of extracellular signal-regulated kinases (Erk1/Erk2) in addition to β-catenin, which could be behind the effect of this cooperation in our cell models. The study clearly suggests that high-risk HPV and EBV coinfection can play an important role in breast cancer progression via Erk1/Erk2 and β-catenin signaling pathways.

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