Identification of E6/E7-Dependent MicroRNAs in HPV-Positive Cancer Cells

A State-of-the-Art Review on the Recent Advances in Exosomes in Oncogenic Virus

Background and Aims

Oncogenic viruses are responsible for approximately 12% of human malignancies, influencing various cancer processes through intricate interactions with host cells. Exosomes (EXOs), nanometric-sized microvesicles involved in cell communication, have emerged as critical mediators in these interactions. This review aims to explore the mechanisms by which EXOs produced by cells infected with oncogenic viruses promote cancer growth, enhance viral transmissibility, and act as immunomodulators.

Methods

A comprehensive review was conducted, focusing on recent studies highlighting the mechanisms by which EXOs facilitate the oncogenic potential of viruses. The analysis included the characterization of exosomal content, such as microRNAs (miRNAs) and proteins, and their effects on tumor microenvironments and immune responses. A search was performed using databases including PubMed, ScienceDirect, and Google Scholar. MeSH keywords related to EXOs, oncogenic viruses, and cancer were used to retrieve relevant review, systematic, and research articles.

Results

Findings indicate that EXOs from oncogenic virus-infected cells carry viral components that facilitate infection and inflammation. These EXOs alter the tumor microenvironment, contributing to the development of virus-associated cancers. Additionally, the review highlights the growing interest among researchers regarding the implications of EXOs in cancer progression and their potential role in enhancing the oncogenicity of viruses.

Conclusion

The findings underscore the pivotal role of EXOs in mediating the oncogenic effects of viruses, suggesting that targeting exosomal pathways may provide new therapeutic avenues for managing virus-associated cancers. Further research is needed to fully elucidate the functional mechanisms of EXOs in viral oncogenesis.

HPV16 E6 promoting cervical cancer progression through down-regulation of miR-320a to increase TOP2A expression

BACKGROUND

Cervical cancer (CC) has become the fourth most common cancer worldwide and it is mainly caused by the infection of human papillomavirus (HPV), especially high-risk HPV16. Aberrant miRNA expression in CC is closely related to HPV16 infection, and the regulation of HPV16 E6 expression can affect a variety of miRNA expression. This study aims to exploring the miRNAs involved in E6 regulation in CC.

METHODS

Our study screened differentially expressed miRNAs in cervical cells of HPV16 infected and uninfected cervical cancer patients by analyzing the GSE81137 dataset of the gene expression omnibus database (GEO), and identified miR-320a that plays an anti-tumor role and is associated with good prognosis of cervical cancer. Explore the effect of HPV16 E6 on the expression of miR-320a in cervical cancer, and verify whether HPV16 E6 regulates the downstream target gene TOP2A expression through miR-320a, thereby affecting cervical cancer cell proliferation, apoptosis, migration, invasion, and EMT in vitro and in vivo.

RESULTS

The bioinformatic methods selected the miR-320a, which was differentially expressed in cervical cells from HPV16-infected patients compared to uninfected patients. We further demonstrated that miR-320a level was regulated by HPV16 E6, which promoted the CC cell proliferation, migration, invasion, and inhibited apoptosis. In addition, we predicted the downstream target genes of miR-320a and confirmed that TOP2A was one of its targeting proteins. Moreover, HPV16 E6 promoted the TOP2A expression in CC cells through down-regulating miR-320a, leading to promoting CC development.

CONCLUSIONS

We confirmed that HPV16 E6 promoted the TOP2A expression through down-regulation of miR-320a, thus promoting CC development, and the HPV16 E6/miR-320a/TOP2A axis may perform as a potential target for CC treatment.

The Triaging Effect of the Human Papillomavirus 16/18 E7 Oncoprotein Assay in HPV 16/18-Positive Patients for High-Grade Cervical Intraepithelial Neoplasia Screening: A Cross-Sectional Study

Objective: To investigate the triaging efficacy of the human papillomavirus (HPV) 16/18 E7 oncoprotein assay for high-grade cervical intraepithelial neoplasia (CIN2+) screening in HPV 16/18-positive patients in a tertiary hospital in China. Methods: We collected 476 cervical cell samples from women who tested positive for HPV 16/18 in the gynecological clinic of Peking Union Medical College Hospital between September 2018 and September 2022 and analyzed them by the HPV 16/18 E7 oncoprotein assay before colposcopy and biopsy. The study assessed the triaging efficacy of the HPV 16/18 E7 oncoprotein assay in HPV 16/18-positive patients by analyzing its performance against the gold standard of histologically confirmed CIN2+. Results: The positive rate of the HPV 16/18 E7 oncoprotein assay was 41.0% (114/278) in the negative for intraepithelial lesions and malignancy/CIN1 group and 80.3% (159/198) in the CIN2+ group. For triage of women with a positive HPV 16/18 test for CIN2+ detection, the HPV 16/18 E7 oncoprotein assay had a sensitivity, specificity, positive predictive value, and negative predictive value of 80.3%, 59.4%, 58.5%, and 80.9%, respectively. Furthermore, longitudinal follow-up of five patients showed a good correlation between the expression of the HPV 16/18 E7 oncoprotein and cervical lesion grades. Conclusions: As a triage method for HPV 16/18-positive patients, the HPV 16/18 E7 oncoprotein assay improves the specificity, reduces the colposcopy referral rate, and has the potential for long-term monitoring of high-grade CIN.

Expression and molecular regulation of non-coding RNAs in HPV-positive head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent malignancy worldwide. Accumulating evidence suggests that persistent HPV infection is closely related to a subset of HNSCC types, and the incidence of human papillomavirus (HPV)-positive HNSCC has been annually increasing in recent decades. Although the carcinogenesis of HPV-positive HNSCC has not been completely elucidated, it has been well confirmed that E6 and E7, the main viral oncoproteins are responsible for the maintenance of malignant transformation, promotion of cell proliferation, and increase in tumor invasion. Moreover, compared with HPV-negative HNSCC, HPV-positive HNSCC shows some special clinical-pathological features, which are possibly related to HPV infection and their specific regulatory mechanisms. Non-coding RNA (ncRNA) is a class of RNA lacking the protein-coding function and playing a critical regulatory role via multiple complex molecular mechanisms. NcRNA is an important regulatory pattern of epigenetic modification, which can exert significant effects on HPV-induced tumorigenesis and progression by deregulating downstream genes. However, the knowledge of ncRNAs is still limited, hence, a better understanding of ncRNAs could provide some insights for exploring the carcinogenesis mechanism and identifying valuable biomarkers in HPV-positive HNSCC. Therefore, in this review, we mainly focused on the expression profile of ncRNAs (including lncRNA, miRNA, and circRNA) and explored their regulatory role in HPV-positive HNSCC, aiming to clarify the regulatory mechanism of ncRNAs and identify valuable biomarkers for HPV-positive HNSCC.

Small extracellular vesicles as key players in cancer development caused by human oncogenic viruses

Background

Exosomes are the smallest group of extracellular vesicles in size from 30 to 150 nm, surrounded by a lipid bilayer membrane, and originate from multivesicular bodies secreted by different types of cells, such as virus-infected cells. The critical role of exosomes is information transfer among cells, representing a unique way for intercellular communication via a load of many kinds of molecules, including various signaling proteins and nucleic acids. In this review, we aimed to comprehensively investigate the role of exosomes in promoting human oncogenic viruses-associated cancers.

Methods

Our search was conducted for published researches between 2000 and 2022 by using several international databases includeing Scopus, PubMed, and Web of Science as well as Google scholar. We also reviewed additional evidence from relevant published articles.

Results

It has been shown that exosomes can create the conditions for viral spread in viral infections. Exosome secretion in a human tumor virus can switch on the cell signaling pathways by transferring exosome-encapsulated molecules, including viral oncoproteins, signal transduction molecules, and virus-encoded miRNAs, into various cells.

Conclusion

Given the role of exosomes in viruses-associated cancers, they can also be considered as molecular targets in diagnosis and treatment.

A HPV16-related prognostic indicator for head and neck squamous cell carcinoma

Background

The human papillomavirus (HPV) is emerging as an important risk factor in head and neck squamous cell carcinoma (HNSCC) patients. This has been observed particularly in the case of HPV16. The HPV16+ HNSCC subtype has distinct pathological, clinical, molecular, and prognostic characteristics. This study aimed to identify potential microRNAs (miRNAs) and their roles in HPV16+ HNSCC progression.

Method

miRNA, mRNA and the clinical data of 519 HNSCC and 44 HNSCC-negative samples were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed miRNAs (DEMs) in HPV16-related HNSCC tissues with prognostic value were selected. DEM levels were assessed based on clinicopathological parameters and overall survival (OS). Target genes were also predicted and functional analysis based on Gene Set Enrichment Analysis (GSEA) were then performed.

Results

In HPV16+ HNSCC tissues, miR-99a-3p and miR-4746-5p were significantly upregulated. In contrast, miR-411-5p was shown to be downregulated. miR-99a-3p^highmiR-411-5p^lowmiR-4746-5p^high expression could estimate improved OS and low frequent perineural invasion (PNI). Predicted target genes were enriched in cell growth, neuroepithelial cell differentiation, MAPK and FoxO signaling pathways. Epithelial mesenchymal transition (EMT) gene set and invasion related genes were downregulated in miR-99a-3p^highmiR-411-5p^lowmiR-4746-5p^high HNSCC patients.

Conclusion

miR-99a-3p, miR-411-5p and miR-4746-5p might participate in HPV16+ HNSCC progression through EMT related pathways and affect prognosis.

EGFR overexpression increases radiotherapy response in HPV-positive head and neck cancer through inhibition of DNA damage repair and HPV E6 downregulation

High-risk Human Papillomavirus (HPV) infections have recently emerged as an independent risk factor in head and neck squamous cell carcinoma (HNSCC). There has been a marked increase in the incidence of HPV-induced HNSCC subtype, which demonstrates different genetics with better treatment outcome. Despite the favourable prognosis of HPV-HNSCC, the treatment modality, consisting of high dose radiotherapy (RT) in combination with chemotherapy (CT), remains similar to HPV-negative tumours, associated with toxic side effects. Epidermal growth factor receptor (EGFR) is overexpressed in over 80% of HNSCC and correlates with RT resistance. EGFR inhibitor Cetuximab is the only FDA approved targeted therapy for both HNSCC subtypes, however the response varies between HNSCC subtypes. In HPV-negative HNSCC, Cetuximab sensitises HNSCC to RT improving survival rates. To reduce adverse cytotoxicity of CT, Cetuximab has been approved for treatment de-escalation of HPV-positive HNSCC. The results of several recent clinical trials have concluded differing outcome to HPV-negative HNSCC. Here we investigated the role of EGFR in HPV-positive HNSCC response to RT. Remarkably, in HPV-positive HNSCC cell lines and in vivo tumour models, EGFR activation was strongly indicative of increased RT response. In response to RT, EGFR activation induced impairment of DNA damage repair and increased RT response. Furthermore, EGFR was found to downregulate HPV oncoproteinE6 expression and induced p53 activity in response to RT. Collectively, our data uncovers a novel role for EGFR in virally induced HNSCC and highlights the importance of using EGFR-targeted therapies in the context of the genetic makeup of cancer.

Potential oncogenic roles of mutant-p53-derived exosomes in the tumor-host interaction of head and neck cancers

The wide-ranging collection of malignancies arising at the upper aerodigestive tract is categorized as head and neck cancer (HNC), the sixth most prevalent cancer worldwide. Infection with human papillomavirus (HPV) or exposure to carcinogens is the leading causes of HPV+ and HPV- HNCs development, respectively. HPV+ and HPV- HNCs are different in clinical and molecular aspects. Specifically, HPV- HNCs tightly associate with missense mutants of the TP53 gene (encoding for the p53 protein), suggesting a central role for mutant p53 gain-of-function (GOF) in driving tumorigenesis. In contrast, in HPV + HNC, the sequence of TP53 typically remains intact, while the protein is degraded. In tumor cells, the status of the TP53 gene affects the cargo of secreted exosomes. In this review, we describe the accumulated knowledge regarding the involvement of exosomes and p53 on cellular interactions between HPV+ and HPV- HNC cells, and the surrounding tumor microenvironment (TME). Moreover, we envision how TP53 status may determine exosomes cargo in HNC, and, consequently, modify the TME. The potential roles of exosomes described herein are based on both our studies and the studies of others on mutant p53-derived exosomes. Specifically, we showed how exosomes are shed by cancer cells harboring mutant p53 communicate with tumor-associated macrophages in the colon as well as with cancer-associated fibroblasts in the lung, creating immunosuppressive conditions and promoting invasiveness. Altogether, exosomes in HNC in the context of TP53 status are understudied and extensive research is required to shed light on the biology of HPV+ and HPV- HNC.

miR‑218 functions as a tumor suppressor gene in cervical cancer

Previous microRNA (miR) microarray analysis revealed that miR‑218 is downregulated in cervical cancer tissues. The present study aimed to further evaluate the expression of miR‑218 in cervical cancer specimens, determine the association between its expression with disease progression, and investigate the roles of miR‑218 in cervical cancer cells. Tissue specimens were obtained from 80 patients with cervical squamous cell carcinoma, 30 patients with high‑grade cervical intraepithelial neoplasia [(CIN) II/III] and 15 patients with low‑grade CIN (CINI); in addition, 60 plasma samples were obtained from patients with cervical cancer, and 15 normal cervical tissue specimens and 30 plasma samples were obtained from healthy women. These samples were used for analysis of miR‑218 expression via reverse transcription‑-quantitative PCR. In addition, tumor cells were transfected with miR‑218 mimics, human papillomavirus (HPV)16 E6/E7 small interfering RNA, or their respective negative controls to determine the viability, colony formation, migration and invasion of cells using MTT, colony formation, wound healing and Transwell assays, respectively. Target genes of miR‑218 were bioinformatically predicted and analyzed using Gene Ontology (GO) terms. The results revealed that miR‑218 was downregulated in the tumor tissues and plasma of patients with cervical cancer, with expression associated with the advanced clinicopathological characteristics of patients, including HPV positivity, tumor size, blood vessel invasion and lymph node metastasis. Furthermore, miR‑218 overexpression reduced tumor cell viability and xenograft growth, and suppressed tumor cell migration and invasion. HPV was detected in 75% of the 80 patients with cervical cancer, and HPV positivity was inversely associated with miR‑218 expression. In addition, bioinformatics analysis predicted that roundabout guidance receptor 1 (ROBO1) was a target gene of miR‑218; miR‑218 overexpression significantly reduced ROBO1 levels. Furthermore, GO analysis revealed that ROBO1 was involved in regulating cell proliferation, adhesion and migration, and the cell cycle. In conclusion, the findings of the present study suggested that miR‑218 may possess antitumor activities in cervical cancer.

Alcohol Exposure Impacts the Composition of HeLa-Derived Extracellular Vesicles

Extracellular vesicles are nanosized vesicles that are under intense investigation for their role in intercellular communication. Extracellular vesicles have begun to be examined for their role in disease protection and their role as disease biomarkers and/or vaccine agents. The goal of this study was to investigate the effects of alcohol exposure on the biogenesis and composition of extracellular vesicles derived from the cervical cancer line, HeLa. The HeLa cells were cultured in exosome-free media and were either mock-treated (control) or treated with 50 mM or 100 mM of alcohol for 24 h and 48 h. Our results demonstrated that alcohol significantly impacts HeLa cell viability and exosome biogenesis/composition. Importantly, our studies demonstrate the critical role of alcohol on HeLa cells, as well as HeLa-derived extracellular vesicle biogenesis and composition. Specifically, these results indicate that alcohol alters extracellular vesicles’ packaging of heat shock proteins and apoptotic proteins. Extracellular vesicles serve as communicators for HeLa cells, as well as biomarkers for the initiation and progression of disease.

Exosomes in virus-associated cancer

Exosomes are phospholipid bilayer membrane-enclosed vesicles in a size from 30 to 150 nm, carrying a variety of active components, such as proteins, mRNA and miRNAs, and are involved in intercellular communication. Exosomes are released by almost all living cells and detected in various biological fluids. Viruses especially oncogenic viruses have been reported to influence the formation of virus-associated cancer through reshaping the tumor microenvironment via exosomes. In this review, a role of exosomes released by oncogenic virus-infected cells in promoting or inhibiting cancer formation is outlined. Moreover, the prospects and challenges of exosome applications in cancer therapies are critically discussed.

Pathogens and Their Effect on Exosome Biogenesis and Composition

Exosomes are nanosized membrane microvesicles (30⁻100 nm) that have the capability to communicate intercellularly and transport cell components (i.e., miRNA, mRNA, proteins and DNA). Exosomes are found in nearly every cell type (i.e., mast cells, dendritic, tumor, and macrophages). There have been many studies that have shown the importance of exosome function as well as their unique packaging and targeting abilities. These characteristics make exosomes ideal candidates to act as biomarkers and therapeutics for disease. We will discuss the biogenesis, composition, and relationship of exosomes with non-viral microbial infections including gram-negative bacteria, gram-positive bacteria, Leishmania and Trypanosoma cruzi.