Recruitment of Antigen Presenting Cells to Skin Draining Lymph Node From HPV16E7-Expressing Skin Requires E7-Rb Interaction

RNA-based gene targeting therapies for human papillomavirus driven cancers

While platinum-based chemotherapy, radiation therapy and or surgery are effective in reducing human papillomavirus (HPV) driven cancer tumours, they have some significant drawbacks, including low specificity for tumour, toxicity, and severe adverse effects. Though current therapies for HPV-driven cancers are effective, severe late toxicity associated with current treatments contributes to the deterioration of patient quality of life. This warrants the need for novel therapies for HPV derived cancers. In this short review, we examined RNA-based therapies targeting the major HPV oncogenes, including short-interfering RNAs (siRNAs) and clustered regularly interspaced short palindromic repeats (CRISPR) as putative treatment modalities. We also explore other potential RNA-based targeting approaches such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and mRNA vaccines as future treatment modalities for HPV cancers. Some of these technologies have already been approved for clinical use for a range of other human diseases but not for HPV cancers. Here we explore the emerging evidence supporting the effectiveness of some of these gene-based therapies for HPV malignancies. In short, the evidence sheds promising light on the feasibility of translating these technologies into a clinically relevant treatment modality for HPV derived cancers and potentially other virally driven human cancers.

Regulatory T Cells but Not IL-10 Impair Cell-Mediated Immunity in Human Papillomavirus E7+ Hyperplastic Epithelium

High-risk human papillomavirus infection can induce cervical and other intraepithelial neoplasia and invasive cancers. A transgenic mouse expressing keratin 14 promotor-driven HPV16 E7 oncoprotein exhibits epithelial hyperplasia and mimics many features of human papillomavirus-related intraepithelial precancers. We have previously demonstrated that HPV16 E7-mediated epithelial hyperplasia suppresses T helper type 1 responses to intradermally delivered antigen and directs differentiation of CD4⁺ T cells towards a Foxp3⁺ regulatory phenotype (Treg). Here we establish that Foxp3⁺ Treg expansion from a transferred naive T-cell population is driven directly by the hyperplastic skin and is independent of pre-existing immune-modulated lymphocytes. However, depletion of endogenous CD25⁺ Tregs before priming of adoptively transferred T cells significantly improves antigen-specific CD8⁺ T-cell responses but not T helper type 1 responses. Deletion of IL-10 had no effect on Treg expansion, epidermal dendritic cell alteration, and suppression of induced T helper type 1 immunity in HPV16 E7-driven hyperplastic mice. Thus, HPV16 E7-mediated epithelial hyperplasia promotes expansion of peripheral Tregs in response to intradermal immunization that suppress antigen-specific CD8⁺ T-cell responses independently of IL-10, but depletion of these Tregs is not sufficient to restore T helper type 1 immunity.

An Overview of Cancer Prevention: Chemoprevention and Immunoprevention

Cancer prevention encompasses a broad spectrum of strategies designed to lower the chance of developing cancer and reduce the morbidity of established cancer. There are three levels of cancer prevention. Eliminating or mitigating cancer risk factors by adopting healthy behaviors and lifestyles, such as avoiding tobacco and alcohol use, exercising, eating a healthy diet, and applying sunscreen to protect against UV exposure, belongs to primary prevention and is the easiest and most effective way of preventing cancer for the general public. Secondary prevention includes screening to identify precancerous lesions and taking intervention measures to prevent disease progression to malignancy. Tertiary prevention refers to reducing or controlling the symptoms and morbidity of established cancer or the morbidity caused by cancer therapy. For high-risk populations, chemopreventive agents, such as selective estrogen receptor modulators (including tamoxifan and raloxifene) in breast cancer prevention and non-steroidal anti-inflammatory drugs (aspirin) in colorectal cancer prevention, and immunoprevention using human papillomavirus and hepatitis B virus vaccines in infection-related cancers have shown clear clinical benefits of reducing cancer incidences. In this review, we will summarize the current status of cancer prevention, focusing on the major agents that are clinically used for chemoprevention and immunoprevention.

Loss of HPV type 16 E7 restores cGAS-STING responses in human papilloma virus-positive oropharyngeal squamous cell carcinomas cells

Human papilloma viruses (HPV) are the main culprit in cervical and oropharyngeal cancers. HPV positive (+) cancers are regarded as 'oncogene addicted', displaying an absolute requirement for the continued expression of the oncogenes for their viability owing their survival, and thus making these genes salient targets for developing specific therapeutic agents. There is a strong association between HPV and oropharyngeal squamous cell carcinomas (OPSCC), a subset of head and neck cancers (HNCs). Alarmingly, HPV-associated OPSCC are on the rise globally, and the number of cases of HPV + OPSCCs surpasses that of cervical cancer in the USA. Here, we show that major HPV oncogenes, E6 and E7, are essential for the survival of HPV positive (+) OPSCCs, making these oncogenes salient targets for HPV-driven OPSCCs. HPV E7 is known to interact with STING, a component of the viral DNA-sensing cGAS-STING machinery which activates a pro-typical anti-viral type I interferon (IFN) response. Our recent work showed that E7 from HPV type 16 is responsible for the blockade of cGAS-STING responses in HPV + OPSCC cells. In this study, we show that CRISPR/Cas9-mediated loss of E7 from HPV + OPSCC cells, SCC2 and SCC104, restored cGAS-STING responses. Future work could involve HPV oncogene targeting leading to HPV + OPSCC tumour regression and that the combined use of STING agonists would induce favourable tumour clearance by activating appropriate anti-tumour responses.

HPV16 E7-Driven Epithelial Hyperplasia Promotes Impaired Antigen Presentation and Regulatory T-Cell Development

Human papillomaviruses infect keratinocytes and can lead to hyperproliferative dysplasia and malignant transformation if not cleared by the immune system. Human papillomavirus has evolved an array of mechanisms to evade and manipulate the immune system to improve replication efficiency and promote persistent infection. We here demonstrate that hyperproliferative skin expressing the high-risk human papillomavirus 16 E7 oncogene as a transgene drives immunomodulation of dendritic cells (DCs), resulting in reduced capacity to take up antigen and prime effector CD4⁺ T cell responses. The phenotype of DCs in the E7-expressing hyperproliferative skin was not reversible by activation through intradermal immunization. Naïve CD4⁺ T cells primed by E7-driven hyperproliferative skin acquired FoxP3 expression and an anergic phenotype. DC and T help modulation was dependent on E7-retinoblastoma protein interaction-driven epithelial hyperproliferation, rather than on expression of E7. Inhibition of binding of E7 to retinoblastoma protein, and of consequent epithelial hyperplasia, was associated with normal skin DC phenotype, and T helper type 1 effector responses to immunization were restored. We conclude that human papillomavirus-induced epithelial hyperplasia modulates epithelial DCs and inhibits T helper type 1 immunity while polarizing T-cell differentiation to a regulatory or anergic phenotype.