| Autor: |
Amanda Psyrri, Paul Weinberger, Panteleimon Kountourakis, Clarence Sasaki, Eirini Pectasides, Eleni Boutati, Theodore Rampias |
| Rok vydání: |
2023 |
| DOI: |
10.1158/1541-7786.c.6542121 |
| Popis: |
We sought to determine the role of human papillomavirus (HPV) E6 and E7 oncogenes in nuclear β-catenin accumulation, a hallmark of activated canonical Wnt signaling pathway. We used HPV16-positive oropharyngeal cancer cell lines 147T and 090, HPV-negative cell line 040T, and cervical cell lines SiHa (bearing integrated HPV16) and HeLa (bearing integrated HPV18) to measure the cytoplasmic and nuclear β-catenin levels and the β-catenin/Tcf transcriptional activity before and after E6/E7 gene silencing. Repression of HPV E6 and E7 genes induced a substantial reduction in nuclear β-catenin levels. Luciferase assay showed that transcriptional activation of Tcf promoter by β-catenin was lower after silencing. The protein levels of β-catenin are tightly regulated by the ubiquitin/proteasome system. We therefore performed expression analysis of regulators of β-catenin degradation and nuclear transport and showed that seven in absentia homologue (Siah-1) mRNA and protein levels were substantially upregulated after E6/E7 repression. Siah-1 protein promotes the degradation of β-catenin through the ubiquitin/proteasome system. To determine whether Siah-1 is important for the proteasomal degradation of β-catenin in HPV16-positive oropharyngeal cancer cells, we introduced a Siah-1 expression vector into 147T and 090 cells and found substantial reduction of endogenous β-catenin in these cells. Thus, E6 and E7 are involved in β-catenin nuclear accumulation and activation of Wnt signaling in HPV-induced cancers. In addition, we show the significance of the endogenous Siah-1–dependent ubiquitin/proteasome pathway for β-catenin degradation and its regulation by E6/E7 viral oncoproteins in HPV16-positive oropharyngeal cancer cells. Mol Cancer Res; 8(3); 433–43 |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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