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Yu L, Majerciak V, Lobanov A, Mirza S, Band V, Liu H, Cam M, Hughes SH, Lowy DR, Zheng ZM. HPV oncogenes expressed from only one of multiple integrated HPV DNA copies drive clonal cell expansion in cervical cancer. mBio 2024; 15:e0072924. [PMID: 38624210 PMCID: PMC11077993 DOI: 10.1128/mbio.00729-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 03/22/2024] [Indexed: 04/17/2024] Open
Abstract
The integration of HPV DNA into human chromosomes plays a pivotal role in the onset of papillomavirus-related cancers. HPV DNA integration often occurs by linearizing the viral DNA in the E1/E2 region, resulting in the loss of a critical viral early polyadenylation signal (PAS), which is essential for the polyadenylation of the E6E7 bicistronic transcripts and for the expression of the viral E6 and E7 oncogenes. Here, we provide compelling evidence that, despite the presence of numerous integrated viral DNA copies, virus-host fusion transcripts originate from only a single integrated HPV DNA in HPV16 and HPV18 cervical cancers and cervical cancer-derived cell lines. The host genomic elements neighboring the integrated HPV DNA are critical for the efficient expression of the viral oncogenes that leads to clonal cell expansion. The fusion RNAs that are produced use a host RNA polyadenylation signal downstream of the integration site, and almost all involve splicing to host sequences. In cell culture, siRNAs specifically targeting the host portion of the virus-host fusion transcripts effectively silenced viral E6 and E7 expression. This, in turn, inhibited cell growth and promoted cell senescence in HPV16+ CaSki and HPV18+ HeLa cells. Showing that HPV E6 and E7 expression from a single integration site is instrumental in clonal cell expansion sheds new light on the mechanisms of HPV-induced carcinogenesis and could be used for the development of precision medicine tailored to combat HPV-related malignancies. IMPORTANCE Persistent oncogenic HPV infections lead to viral DNA integration into the human genome and the development of cervical, anogenital, and oropharyngeal cancers. The expression of the viral E6 and E7 oncogenes plays a key role in cell transformation and tumorigenesis. However, how E6 and E7 could be expressed from the integrated viral DNA which often lacks a viral polyadenylation signal in the cancer cells remains unknown. By analyzing the integrated HPV DNA sites and expressed HPV RNAs in cervical cancer tissues and cell lines, we show that HPV oncogenes are expressed from only one of multiple chromosomal HPV DNA integrated copies. A host polyadenylation signal downstream of the integrated viral DNA is used for polyadenylation and stabilization of the virus-host chimeric RNAs, making the oncogenic transcripts targetable by siRNAs. This observation provides further understanding of the tumorigenic mechanism of HPV integration and suggests possible therapeutic strategies for the development of precision medicine for HPV cancers.
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Affiliation(s)
- Lulu Yu
- Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Vladimir Majerciak
- Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Alexei Lobanov
- CCR Collaborative Bioinformatics Resource (CCBR), National Cancer Institute, Bethesda, Maryland, USA
| | - Sameer Mirza
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Vimla Band
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Haibin Liu
- Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Maggie Cam
- CCR Collaborative Bioinformatics Resource (CCBR), National Cancer Institute, Bethesda, Maryland, USA
| | - Stephen H. Hughes
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Douglas R. Lowy
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Zhi-Ming Zheng
- Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
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Wittrup KD. Antitumor Antibodies Can Drive Therapeutic T Cell Responses. Trends Cancer 2017; 3:615-620. [PMID: 28867165 DOI: 10.1016/j.trecan.2017.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/03/2017] [Accepted: 07/05/2017] [Indexed: 12/31/2022]
Abstract
The classical view of therapeutic monoclonal antibodies (mAbs) against tumor-associated antigens (TAAs) is that their mechanism of action is dominated by signal blocking or the cytotoxicity of Fc-driven innate immune effector functions. We review here a mounting body of evidence that anti-TAA mAbs are capable of profoundly synergizing with T cell-directed immunotherapies such as checkpoint blockade and adoptive cell therapy. Two key components account for this synergy: (i) a self-vaccinal effect mediated by dendritic cells (DCs); and (ii) an inflammatory repolarization of the tumor microenvironment. Efficient exploitation of these mechanisms has tremendous therapeutic potential.
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Affiliation(s)
- K Dane Wittrup
- Biological Engineering and Chemical Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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