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Specific inhibition of a human papillomavirus E2 trans-activator by intracellular delivery of its repressor
R B Pepinsky1, E J Androphy, K Corina
1Biogen, Inc., Cambridge, MA 02142.
Abstract:
Papillomaviruses are the causative agents of benign and malignant epithelial tumors of the skin and mucosa. They encode a DNA-binding protein, E2, that regulates viral transcription and replication, making it an important therapeutic target. By deleting the amino-terminal trans-activation domain of human papillomavirus type 16 (HPV-16) E2 while retaining its carboxy-terminal DNA binding and dimerization domain, an E2 repressor (E2R) that efficiently inhibits transcriptional activation by full-length HPV E2 was generated. To deliver this repressor protein into animal cells, we have utilized the human immunodeficiency virus type 1 (HIV-1) Tat protein which itself is taken up efficiently into intact cells. Chimeras of E2R and the cellular uptake domain of Tat specifically inhibited E2-dependent reporter gene expression in COS-7 cells. Treatment of cervical intraepithelial neoplasia cells having episomally replicating HPV-31 DNA with this Tat-E2R protein led to a dose-dependent loss of HPV DNA copies and inhibition of cell growth. Tat-mediated delivery can be a valuable tool for assessing protein function and may allow the development of novel therapeutic proteins having intracellular targets.
Insights
Researchers developed a novel therapeutic protein by combining a human papillomavirus (HPV) E2 repressor with HIV-1 Tat protein for cellular delivery. This Tat-E2R protein effectively inhibited HPV replication and cell growth in preclinical models.
Area of Science:
- Virology
- Molecular Biology
- Oncology
Background:
- Papillomaviruses cause epithelial tumors and possess an E2 protein crucial for viral transcription and replication.
- The E2 protein is a significant therapeutic target due to its regulatory role.
Purpose of the Study:
- To develop a novel therapeutic strategy targeting papillomavirus replication.
- To assess the efficacy of a novel engineered protein delivered via a cell-penetrating peptide.
Main Methods:
- Generated an E2 repressor (E2R) by modifying the HPV-16 E2 protein.
- Fused E2R with the HIV-1 Tat protein's cell-penetrating domain for enhanced cellular uptake.
- Tested the Tat-E2R chimera's ability to inhibit E2-dependent gene expression in COS-7 cells.
- Evaluated the Tat-E2R protein's effect on HPV-31 DNA replication and cervical cancer cell growth.
Main Results:
- The Tat-E2R chimera efficiently inhibited E2-dependent reporter gene expression.
- Treatment with Tat-E2R resulted in a dose-dependent reduction of HPV-31 DNA copies in cervical cancer cells.
- Tat-E2R treatment inhibited the growth of cervical intraepithelial neoplasia cells.
Conclusions:
- Tat-mediated delivery is a viable method for introducing functional proteins into cells.
- Engineered E2 repressor proteins delivered by Tat show promise for targeting papillomavirus infections.
- This approach may lead to new therapeutic strategies for epithelial tumors caused by papillomaviruses.