Related Experiment Video
Updated: Jun 17, 2026
Use of Interferon-γ Enzyme-linked Immunospot Assay to Characterize Novel T-cell Epitopes of Human Papillomavirus
Published on: March 8, 2012
Expression of human papillomavirus type 16 E7 oncoprotein alters keratinocytes expression profile in response to
Enrique Boccardo1, Carina Victoria Manzini Baldi, Alex Fiorini Carvalho
1Virology Group, Ludwig Institute for Cancer Research, São Paulo 01323-903, Brazil. eboccardo@ludwig.org.br
Abstract:
Acute expression of E7 oncogene from human papillomavirus (HPV) 16 or HPV18 is sufficient to overcome tumor necrosis factor (TNF)-alpha cytostatic effect on primary human keratinocytes. In the present study, we investigated the molecular basis of E7-induced TNF resistance through a comparative analysis of the effect of this cytokine on the proliferation and global gene expression of normal and E7-expressing keratinocytes. Using E7 functional mutants, we show that E7-induced TNF resistance correlates with its ability to mediate pRb degradation and cell transformation. On the other hand, this effect does not depend on E7 sequences required to override DNA damage-induced cell cycle arrest or extend keratinocyte life span. Furthermore, we identified a group of 66 genes whose expression pattern differs between normal and E7-expressing cells upon cytokine treatment. These genes are mainly involved in cell cycle regulation suggesting that their altered expression may contribute to sustained cell proliferation even in the presence of a cytostatic stimulus. Differential expression of TCN1 (transcobalamin I), IFI44 (Interferon-induced protein 44), HMGB2 (high-mobility group box 2) and FUS [Fusion (involved in t(12;16) in malignant liposarcoma)] among other genes were further confirmed by western-blot and/or real-time polymerase chain reaction. Moreover, FUS upregulation was detected in HPV-positive cervical high-grade squamous intraepithelial lesions when compared with normal cervical tissue. Further evaluation of the role of such genes in TNF resistance and HPV-associated disease development is warranted.
Insights
Human papillomavirus (HPV) E7 oncogene confers resistance to tumor necrosis factor-alpha (TNF-alpha) in keratinocytes by degrading pRb. This resistance is linked to altered expression of cell cycle genes, including FUS, which is upregulated in HPV-associated cervical lesions.
Area of Science:
- Oncology
- Virology
- Molecular Biology
Background:
- Human papillomavirus (HPV) oncoproteins, particularly E7, are implicated in cervical cancer development.
- Tumor necrosis factor-alpha (TNF-alpha) typically inhibits keratinocyte proliferation.
- Understanding how HPV evades TNF-alpha-induced growth inhibition is crucial for cancer research.
Purpose of the Study:
- To elucidate the molecular mechanisms behind E7-mediated resistance to TNF-alpha in keratinocytes.
- To identify genes and pathways affected by E7 expression in the context of TNF-alpha treatment.
- To investigate the role of E7 in cell transformation and its correlation with TNF-alpha resistance.
Main Methods:
- Comparative analysis of normal and E7-expressing keratinocytes treated with TNF-alpha.
- Utilized E7 functional mutants to dissect specific E7 activities.
- Global gene expression profiling and validation using Western blot and real-time PCR.
- Analysis of FUS expression in clinical HPV-positive cervical lesions.
Main Results:
- E7 expression confers resistance to TNF-alpha's cytostatic effects in keratinocytes.
- E7-induced TNF-alpha resistance is dependent on pRb degradation and cell transformation capabilities of E7.
- Identified 66 differentially expressed genes, predominantly involved in cell cycle regulation, in E7-expressing cells upon TNF-alpha treatment.
- Confirmed upregulation of TCN1, IFI44, HMGB2, and FUS.
- FUS upregulation was observed in HPV-positive cervical intraepithelial lesions.
Conclusions:
- E7 oncogene mediates TNF-alpha resistance in keratinocytes through pRb degradation and cell transformation.
- Altered expression of cell cycle-related genes contributes to sustained proliferation despite TNF-alpha.
- FUS is a potential biomarker for HPV-associated cervical lesions and warrants further investigation in TNF-alpha resistance and disease progression.
Related Concept Videos
02:38Mitogens and the Cell Cycle
01:33Cancer-Critical Genes I: Proto-oncogenes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
02:23Abnormal Proliferation
01:06Induced Pluripotent Stem Cells
Somatic cells are...
02:07Tumor Progression
Colon cancer is one of the best-documented examples of tumor progression. Early mutation in the APC gene in colon cells causes a small growth on the colon wall called a polyp. With time, this polyp grows into a benign, pre-cancerous tumor. Further...
02:07Tumor Progression
Colon cancer is one of the best-documented examples of tumor progression. Early mutation in the APC gene in colon cells causes a small growth on the colon wall called a polyp. With time, this polyp grows into a benign, pre-cancerous tumor. Further...