The role of RNA-binding proteins in the processing of mRNAs produced by carcinogenic papillomaviruses

The splicing factor kinase, SR protein kinase 1 (SRPK1) is essential for late events in the human papillomavirus life cycle

Human papillomaviruses (HPV) infect epithelia to cause benign lesions or warts. However, the so-called "high risk" HPVs infecting the anogenital region and the oropharynx can cause precancerous lesions that may progress to malignant tumours. Understanding the HPV life cycle is important to the discovery of novel antiviral therapies. HPV uses cellular splicing to produce the full suite of viral mRNAs. Members of the serine/arginine rich (SR) protein family can positively regulate splicing. SR protein activity and cellular location is regulated by phosphorylation of their serine-arginine domains. SR protein kinases (SRPK) can phosphorylate SR proteins. This licenses their nuclear entry and promotes nuclear splicing together with another SR protein kinase, Clk1. SRPIN340 is a specific inhibitor of SRPK1. It has been reported to inhibit replication of HCV, Sindbis virus and HIV. We show here that SRPIN340 inhibits the expression of the viral replication and transcription factor, E2. Loss of HPV E4 and L1 late proteins was also observed. RNA sequencing showed SRPIN340 treatment resulted in gene expression changes opposite to those induced by HPV16 infection. In particular, the loss of the epithelial barrier was restored. SRPIN340 treatment led to changes in alternative splicing of 935 RNAs and pathway analysis showed a predominance of changes to RNAs encoding proteins involved in chromatin conformation, DNA repair and RNA processing. Short term SRPIN340 treatment (two to three days) was not associated with changes in proliferation or differentiation of keratinocytes. Since SRPK1 controls the E2 viral replication and transcription factor, targeting this kinase, or the phosphorylation events it mediates, could be considered as a therapeutic strategy for HPV16 infection.

Host microRNA-31-5p represses oncogenic herpesvirus lytic reactivation by restricting the RNA-binding protein KHDRBS3-mediated viral gene expression

Oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV), an etiological agent of Kaposi's sarcoma and primary effusion lymphoma, employs a biphasic life cycle consisting of latency and lytic replication to achieve lifelong infection. Despite its essential role in KSHV persistence and tumorigenicity, much remains unknown about how KSHV lytic reactivation is regulated. Leveraging high-throughput transcriptomics, we identify microRNA-31-5p (miR-31-5p) as a key regulator of KSHV lytic reactivation capable of restricting KSHV entry into the lytic replication cycle. Ectopic expression of miR-31-5p impairs KSHV lytic gene transcription and production of lytic viral proteins, culminating in dramatic reduction of infectious virion production during KSHV reactivation. miR-31-5p overexpression also markedly reduces the expression of critical viral early genes, including the master regulator of the latent-lytic switch, KSHV replication and transcription activator (RTA) protein. Through mechanistic studies, we demonstrate that miR-31-5p represses KSHV lytic reactivation by directly targeting the KH domain protein KHDRBS3, an RNA-binding protein known to regulate RNA processing including alternative splicing. Our study highlights KHDRBS3 as an essential proviral host factor that is key to the successful completion of KSHV lytic replication and suggests its novel function in viral lytic gene transcription during KSHV reactivation. Taken together, these findings reveal a previously unrecognized role for the miR-31-5p/KHDRBS3 axis in regulating the KSHV latency-lytic replication switch and provide insights into gene expression regulation of lytic KSHV, which may be leveraged for lytic cycle-targeted therapeutic strategies against KSHV-associated malignancies.

Integrative machine learning frameworks to uncover specific protein signature in neuroendocrine cervical carcinoma

OBJECTIVE

Neuroendocrine cervical carcinoma (NECC) is a rare but highly aggressive tumor. The clinical management of NECC follows neuroendocrine neoplasms and cervical cancer in general. However, the diagnosis and prognosis of NECC remain dismal. The aim of this study was to identify a specific protein signature for the diagnosis of NECC.

METHODS

Protein and gene expression data for NECC and other cervical cancers were retrieved or downloaded from self-collected samples or public resources. Eleven machine-learning algorithms were packaged into 66 combinations, of which we selected the optimal algorithm, including randomForest, SVM-RFE, and LASSO, to select key NECC specific dysregulated proteins (kNsDEPs). The diagnostic effect of kNsDEPs was validated by a set of predictive models and immunohistochemical staining method. The dysregulation patterns of kNsDEPs were further investigated in other neuroendocrine carcinomas.

RESULTS

Our results showed that NECC displays distinctive biological characteristics, such as HPV18 infection, and exhibits unique molecular features, particularly an enrichment in cytoskeleton-related functions. Furthermore, secretagogin (SCGN), adenylyl cyclase-associated protein 2 (CAP2), and calcyclin-binding protein (CACYBP) were identified as kNsDEPs. These kNsDEPs play a central role in cytoskeleton protein binding and showcase robust diagnostic ability and specificity for NECC. Moreover, the concurrent upregulation of SCGN and CACYBP, along with the downregulation of CAP2, represents a unique feature of NECC, distinguishing it from other neuroendocrine carcinomas.

CONCLUSIONS

This study uncovers the significance of kNsDEPs and elucidates their regulated networks in the context of NECC. It highlights the pivotal role of kNsDEPs in NECC diagnosis, thus offering promising prospects for the development of diagnostic biomarkers for NECC.

An exploration of the natural and acquired immunological mechanisms to high-risk human papillomavirus infection and unmasking immune escape in cervical cancer: A concise synopsis

The most common STD that triggers cervical cancer is the human papillomavirus. More than 20 types of human papillomavirus (HPV) can induce uterine cervical cancer. Almost all women acquire genital HPV infection soon after their first intercourse, with most of them clearing the virus within 3 years. An immune response is necessary to clear. The first responders to HPV infection are the innate immune system elements composed of macrophages, keratinocytes, natural killer cells, and natural killer T-lymphocytic (NKT) cells. Cytotoxic T lymphocytes (CTLs) comprise the second line of defense and kill HPV16-infected cells expressing various peptides derived from their transforming early viral oncoproteins, mainly E2•E6. Even though HPV can manage to trick away our immune systems, first of all, it is important to emphasize that HPV replication does not kill the host cells. It does not replicate viral antigens or cause inflammation. The HPV16 E6 and E7 genes suppress host cell type 1 interferons (IFNs), which are detectable after infection. The patient may have immunological tolerance; hence, there are no costimulatory signals from inflammatory cytokines like IFNs during antigen recognition. Evidence shows that HlA class I generations have been inhibited by HPV16 E5, which could protect this tumor cell from CTL attack. HPV16 E7 is responsible for initiating immunotolerance and increasing regulatory T cells (Treg) to repress immunological regression. Evasion from immune system protection plays a critical role in the outcome of persistent HPV infection and the development of cervical cancer. Vaccination against HPV16 and 18 during adolescence is the most effective method for preventing cervical cancer in women, considering the immunological processes involved.

Alternative splicing in the genome of HPV and its regulation

Persistent infection with high-risk human papillomavirus (HR-HPV) is the main cause of cervical cancer. These chronic infections are characterized by high expression of the HPV E6 and E7 oncogenes and the absence of the L1 and L2 capsid proteins. The regulation of HPV gene expression plays a crucial role in both the viral life cycle and rare oncogenic events. Alternative splicing of HPV mRNA is a key mechanism in post-transcriptional regulation. Through alternative splicing, HPV mRNA is diversified into various splice isoforms with distinct coding potentials, encoding multiple proteins and influencing the expression of HPV genes. The spliced mRNAs derived from a donor splicing site within the E6 ORF and one of the different acceptor sites located in the early mRNA contain E6 truncated mRNAs, named E6*. E6* is one of the extensively studied splicing isoforms. However, the role of E6* proteins in cancer progression remains controversial. Here, we reviewed and compared the alternative splicing events occurring in the genomes of HR-HPV and LR-HPV. Recently, new HPV alternative splicing regulatory proteins have been continuously discovered, and we have updated the regulation of HPV alternative splicing. In addition, we summarized the functions of known splice isoforms from three aspects: anti-tumorigenic, tumorigenic, and other cancer-related functions, including not only E6*, but also E6^E7, E8^E2, and so on. Comprehending their contributions to cancer development enhances insights into the carcinogenic mechanisms of HPV and explores the potential utility of alternative splicing in the diagnosis and treatment of cervical cancer.

hnRNP H controls alternative splicing of human papillomavirus type 16 E1, E6, E7, and E6^E7 mRNAs via GGG motifs

The mRNAs encoding the human papillomavirus type 16 (HPV16) E6 and E7 oncogene mRNAs are subjected to extensive alternative RNA splicing at multiple regulated splice sites. One of the most extensively used 5'-splice sites in the HPV16 genome is named SD880 and is located immediately downstream of the E7 open reading frame. Here, we show that a cluster of three GGG-motifs adjacent to HPV16 SD880 interacts with heterogeneous nuclear ribonucleoprotein (hnRNP) H that cooperates with SD880 to stimulate splicing to the upstream HPV16 3'-splice site SA742. This splice site is located in the E7 coding region and is required for the production of the HPV16 226^742 mRNA that encodes the E6^E7 fusion protein. Enhancement of HPV16 E6^E7 mRNA production by hnRNP H occurred at the expense of the intron-retained E6 mRNAs and the spliced E7 mRNAs, demonstrating that hnRNP H controls the relative levels of E6, E7, and E6^E7 proteins. Unexpectedly, overexpression of hnRNP H also promoted retention of the downstream E1 encoding intron and enhanced E1 protein production. We concluded that hnRNP H plays an important role in the HPV16 gene expression program.IMPORTANCEHere, we show that hnRNP H binds to multiple GGG-motifs downstream of human papillomavirus type 16 (HPV16) splice site SD880 and acts in concert with SD880 to promote expression of the HPV16 E6^E7 mRNA. The E6^E7 protein has been shown previously to stabilize the HPV16 E6 and E7 oncoproteins and may as such contribute to the carcinogenic properties of HPV16. In its capacity of major regulator of HPV16 oncogene expression, hnRNP H may be exploited as a target for antiviral drugs to HPV16.

RNA binding protein RALY facilitates colorectal cancer metastasis via enhancing exosome biogenesis in m6A dependent manner

Tumor metastasis is the leading cause of cancer-related death in patients with colorectal cancer (CRC). Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA-binding proteins, involved in the tumorigenesis and metastasis of various cancers. However, the molecular mechanisms of hnRNPs in CRC metastasis remain unclear. This study aims to uncover the pivotal roles and molecular mechanisms of hnRNPs in CRC metastasis. Clinical database analysis suggested that the expression of hnRNP-Associated with Lethal Yellow (RALY, an important member of hnRNPs) was strongly correlated with the aggressiveness and survival of CRC patients. Gain- and loss-of-function studies demonstrated that RALY promotes the production of exosomes by increasing the formation of multivesicular bodies (MVBs) and enhancing the fusion of MVBs with the plasma membrane. Notably, RALY directly interacts with phospholipase D2 (PLD2) to enable exosome biogenesis, and cooperates with RBM15b to control PLD2 mRNA stability in an m6A-dependent manner. RALY-mediated exosome secretion activates pro-tumor macrophages and further facilitates CRC metastasis, while rescue experiments in vivo further confirmed that RALY-mediated exosome biogenesis facilitates CRC metastasis. Collectively, our findings demonstrate that RALY promotes exosome biogenesis and facilitates colorectal cancer metastasis by upregulating PLD2 and enhancing exosome production in an m6A-dependent manner, suggesting potential therapeutic strategies for combating CRC metastasis.

Knowledge on Human Papillomavirus Infections, Cancer Biology, Immune Interactions, Vaccination Coverage and Common Treatments: A Comprehensive Review

Human papillomavirus (HPV) is a circular, double-stranded DNA virus and recognized as the most prevalent sexually transmitted infectious agent worldwide. The HPV life cycle encompasses three primary stages. First, the virus infiltrates the basal cells of the stratified epidermis. Second, there is a low-level expression of viral genes and preservation of the viral genome in the basal layer. Lastly, productive replication of HPV occurs in differentiated cells. An effective immune response, involving various immune cells, including innate immunity, keratinocytes, dendritic cells, and natural killer T cells, is instrumental in clearing HPV infection and thwarting the development of HPV-associated tumors. Vaccines have demonstrated their efficacy in preventing genital warts, high-grade precancerous lesions, and cancers in females. In males, the vaccines can also aid in preventing genital warts, anal precancerous lesions, and cancer. This comprehensive review aims to provide a thorough and detailed exploration of HPV infections, delving into its genetic characteristics, life cycle, pathogenesis, and the role of high-risk and low-risk HPV strains. In addition, this review seeks to elucidate the intricate immune interactions that govern HPV infections, spanning from innate immunity to adaptive immune responses, as well as examining the evasion mechanisms used by the virus. Furthermore, the article discusses the current landscape of HPV vaccines and common treatments, contributing to a holistic understanding of HPV and its associated diseases.

Alteration of RNA m6A methylation mediates aberrant RNA binding protein expression and alternative splicing in condyloma acuminatum

Background

Condyloma acuminatum (CA) is caused by low-risk human papillomavirus, and is characterized by high recurrence after treatment. The RNA modification N6-methyladenosine (m6A) plays an important role during diverse viral infections, including high-risk HPV infection in cervical cancer. However, it is unclear whether low-risk HPV infection changes the RNA m6A methylation in CA.

Methods

High-throughputm6A-sequencing was performed to profile the transcriptome-wide mRNA modifications of CA tissues infected by LR-HPVs and the paired normal tissues from CA patients. We further investigated the regulation of alternative splicing by RNA binding proteins (RBPs) with altered m6A modification and constructed a regulatory network among these RBPs, regulated alternative splicing events (RASEs) and regulated alternative splicing genes (RASGs) in CA.

Results

The results show that the m6A level in CA tissues differed from that in the paired controls. Furthermore, cell cycle- and cell adhesion- associated genes with m6A modification were differentially expressed in CA tissues compared to the paired controls. In particular, seven RNA binding protein genes with specific m6A methylated sites, showed a higher or lower expression at the mRNA level in CA tissues than in the paired normal tissues. In addition, these differentially expressed RNA binding protein genes would regulate the alternative splicing pattern of apoptotic process genes in CA tissue.

Conclusions

Our study reveals a sophisticated m6A modification profile in CA tissue that affects the response of host cells to HPV infection, and provides cues for the further exploration of the roles of m6A and the development of a novel treatment strategy for CA.

HPV and RNA Binding Proteins: What We Know and What Remains to Be Discovered

Papillomavirus gene regulation is largely post-transcriptional due to overlapping open reading frames and the use of alternative polyadenylation and alternative splicing to produce the full suite of viral mRNAs. These processes are controlled by a wide range of cellular RNA binding proteins (RPBs), including constitutive splicing factors and cleavage and polyadenylation machinery, but also factors that regulate these processes, for example, SR and hnRNP proteins. Like cellular RNAs, papillomavirus RNAs have been shown to bind many such proteins. The life cycle of papillomaviruses is intimately linked to differentiation of the epithelial tissues the virus infects. For example, viral late mRNAs and proteins are expressed only in the most differentiated epithelial layers to avoid recognition by the host immune response. Papillomavirus genome replication is linked to the DNA damage response and viral chromatin conformation, processes which also link to RNA processing. Challenges with respect to elucidating how RBPs regulate the viral life cycle include consideration of the orchestrated spatial aspect of viral gene expression in an infected epithelium and the epigenetic nature of the viral episomal genome. This review discusses RBPs that control viral gene expression, and how the connectivity of various nuclear processes might contribute to viral mRNA production.

RNA elements that control human papillomavirus mRNA splicing-targets for therapy?

Human papillomaviruses (HPVs) cause more than 4.5% of all cancer in the world and more than half of these cases are attributed to human papillomavirus type 16 (HPV16). Prophylactic vaccines are available but antiviral drugs are not. Novel targets for therapy are urgently needed. Alternative RNA splicing is extensively used by HPVs to express all their genes and HPV16 is no exception. This process must function to perfection since mis-splicing could perturb the HPV gene expression program by altering mRNA levels or by generating dysfunctional mRNAs. Cis-acting RNA elements on the viral mRNAs and their cognate cellular trans-acting factors control papillomavirus RNA splicing. The precise but delicate nature of the splicing process renders splicing sensitive to interference. As such, papillomavirus RNA splicing is a potential target for therapy. Here we summarize our current understanding of cis-acting HPV16 RNA elements that control HPV16 mRNA splicing via cellular proteins and discuss how they may be exploited as targets for therapy to papillomavirus infections and cancer.

The human papillomavirus late life cycle and links to keratinocyte differentiation

Regulation of human papillomavirus (HPV) gene expression is tightly linked to differentiation of the keratinocytes the virus infects. HPV late gene expression is confined to the cells in the upper layers of the epithelium where the virus capsid proteins are synthesized. As these proteins are highly immunogenic, and the upper epithelium is an immune-privileged site, this spatial restriction aids immune evasion. Many decades of work have contributed to the current understanding of how this restriction occurs at a molecular level. This review will examine what is known about late gene expression in HPV-infected lesions and will dissect the intricacies of late gene regulation. Future directions for novel antiviral approaches will be highlighted.

A novel HPV16 splicing enhancer critical for viral oncogene expression and cell immortalization

High-risk carcinogenic human papillomaviruses (HPVs), e.g. HPV16, express the E6 and E7 oncogenes from two mRNAs that are generated in a mutually exclusive manner by splicing. The HPV16 E7 mRNA, also known as the E6*I/E7 mRNA, is produced by splicing between splice sites SD226 and SA409, while E6 mRNAs retain the intron between these splice sites. We show that splicing between HPV16 splice sites SD226 and SA409 is controlled by a splicing enhancer consisting of a perfect repeat of an adenosine-rich, 11 nucleotide sequence: AAAAGCAAAGA. Two nucleotide substitutions in both 11 nucleotide sequences specifically inhibited production of the spliced E6*I/E7 mRNA. As a result, production of E7 protein was reduced and the ability of HPV16 to immortalize human primary keratinocytes was abolished. The splicing-enhancing effect was mediated by the cellular TRAP150/THRAP3 protein that also enhanced splicing of other high-risk HPV E6*I/E7 mRNAs, but had no effect on low-risk HPV mRNAs. In summary, we have identified a novel splicing enhancer in the E6 coding region that is specific for high-risk HPVs and that is critically linked to HPV16 carcinogenic properties.

Novel Serine-Arginine Protein Kinase Inhibitors for Treating Cancer

Described herein are novel serine-arginine protein kinase (SRPK) inhibitors, their pharmaceutical compositions, the use of such compounds in treating cancer, and processes for preparing such compounds.

Evaluation of the clinical efficacy of vaginal treatment options for persistent high-risk human papillomavirus infection after excisional treatment of cervical high-grade squamous intraepithelial lesions: a systematic review and Bayesian network meta-analysis

BACKGROUND

To evaluate the clinical efficacy of different vaginal administration on cervical persistent high-risk human papillomavirus (HR-HPV) infection after excisional treatment for high-grade squamous intraepithelial lesions (HSIL).

METHODS

Six databases (PubMed, EmBase, Cochrane Central, China Knowledge Network database, China Biomedical Literature Service, and WanFang database) were searched to collect randomized controlled trials (RCTs) of various types of vaginal administration compared to no treatment on persistent HR-HPV infection after HSIL excisional treatment, and comprehensive analysis of the clearance of different drugs on HR-HPV was performed using Bayesian reticulation meta-analysis.

RESULTS

The study analyzed the efficacy of eight interventions, including Interferon, Baofukang, Paiteling, Bletilla striata Sanhuang Powder, Lactobacilli vaginal capsules, Fuanning + Interferon, Interferon + Lactobacilli vaginal capsules, and Interferon + Baofukang, on the clearance of HR-HPV after excisional treatment through pooling and analyzing data from 52 RCTs. The results of the study demonstrated that Interferon + Lactobacilli vaginal capsules [OR 16.0 (95% CIs 8.1-32.0)], Interferon + Fuanning [OR 16.0 (95% CIs 1.1-52.0)], and Interferon + Baofukang [OR 14.0 (95% CIs 6.8-28.0)] were all found to significantly improve postoperative HR-HPV clearance rates when compared to no treatment. Furthermore, when studies with high-risk bias were excluded, Interferon + Lactobacilli vaginal capsules [OR 8.6 (95% CIs 4.7-19.0)] and Interferon + Baofukang [OR 22.0 (95% CIs 8.7-59.0)] were still found to be positively associated with increased postoperative HR-HPV clearance rate. Additionally, the study´s results also indicate that Interferon + Baofukang was effective in enhancing the postoperative HR-HPV clearance rates, mainly when the studies were restricted to a follow-up period of at least 12 months [OR 9.6 (95% CIs 2.9-34.0)]. However, it is important to note that the majority of the trials (29 out of 52, 51.6%) were rated as moderate to high risk of bias, and the certainty of the evidence was moderate to very low.

CONCLUSION

The application of various forms of vaginal administration, except for individual use of Lactobacilli vaginal capsules, is more efficacious than no treatment in patients with cervical persistent HR-HPV infection after excisional treatment. However, all of the estimates of the effect size for change in the efficiency of HR-HPV clearance are uncertain. Our confidence in effect estimates and ranking of treatments is low, which needs larger, more rigorous, and longer follow-up RCTs to resolve.

hnRNP K induces HPV16 oncogene expression and promotes cervical cancerization

PURPOSE

This study aims to explore the expression of hnRNP K in cervical carcinogenesis and to investigate the regulatory role of hnRNP K on HPV16 oncogene expression as well as biological changes in cervical cancer cells.

METHODS

In total 1042 subjects, including 573 with the normal cervix and 469 with different grades of cervical lesions were enrolled in this study to explore the association between hnRNP K and HPV16 oncogene expression in cervical carcinogenesis. Additionally, the Gene Omnibus (GEO) database was used to analyze hnRNP K mRNA expression in cervical cancerization. Meanwhile, the effects of hnRNP K on cell biological functions and HPV16 oncogene expression were investigated in Siha cells. Moreover, Function analyses were conducted using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases after ChIP-seq.

RESULTS

hnRNP K was highly expressed in cervical cancer and precancerous lesions, and positively correlated with HPV16 E6, but negatively correlated with HPV16 E2 and HPV16 E2/E6 ratio. hnRNP K induced cell proliferation, inhibited apoptosis and caused cell cycle arrest in the S phase, and particularly increased HPV16 E6 protein expression.

CONCLUSION

This study revealed that hnRNP K overexpression has important warning significance for the malignant transformation of cervical lesions, and could be used as a potential therapeutic target for inhibiting the carcinogenicity of HPV16 and prevention of cervical carcinogenesis.

Immune landscape of viral cancers: Insights from single-cell sequencing

Viral infections trigger a wide range of immune responses thought to drive tumorigenesis and malignant progression. Dissecting virus-induced changes in the tumor immune microenvironment (TIME) is therefore crucial to identify key leukocyte populations that may represent novel targets for cancer therapy. Single-cell sequencing approaches have now been widely applied to the analysis of various tumors, thus enabling multiomics characterization of the highly heterogeneous TIME that bulk-sequencing cannot fully elucidate. In this review, we summarized key recent findings from sequencing studies of the immune infiltrate and antitumor response in virus-associated cancers at single cell resolution. Additionally, we also reviewed recent developments in immunotherapy for virus-associated cancers. We anticipate that the strategic use of single-cell sequencing will advance our understanding of the TIME of viral cancers, leading to the development of more potent novel treatments.

Advanced Nanomedicine for High-Risk HPV-Driven Head and Neck Cancer

The incidence of high-risk Human Papillomavirus (HR-HPV)-driven head and neck squamous cell carcinoma (HNSCC) is on the rise globally. HR-HPV-driven HNSCC displays molecular and clinical characteristics distinct from HPV-uninvolved cases. Therapeutic strategies for HR-HPV-driven HNSCC are under investigation. HR-HPVs encode the oncogenes E6 and E7, which are essential in tumorigenesis. Meanwhile, involvement of E6 and E7 provides attractive targets for developing new therapeutic regimen. Here we will review some of the recent advancements observed in preclinical studies and clinical trials on HR-HPV-driven HNSCC, focusing on nanotechnology related methods. Materials science innovation leads to great improvement for cancer therapeutics including HNSCC. This article discusses HPV-E6 or -E7- based vaccines, based on plasmid, messenger RNA or peptide, at their current stage of development and testing as well as how nanoparticles can be designed to target and access cancer cells and activate certain immunology pathways besides serving as a delivery vehicle. Nanotechnology was also used for chemotherapy and photothermal treatment. Short interference RNA targeting E6/E7 showed some potential in animal models. Gene editing by CRISPR-CAS9 combined with other treatments has also been assessed. These advancements have the potential to improve the outcome in HR-HPV-driven HNSCC, however breakthroughs are still to be awaited with nanomedicine playing an important role.

Post-Transcriptional Gene Regulation by HPV 16E6 and Its Host Protein Partners

Human papillomavirus type 16 (HPV 16) is the most common oncogenic type of HPV in cervical, anogenital, and head and neck cancers, making HPV 16 an important high-risk HPV (HR HPV) type. To create an environment permissible for viral maintenance and growth and to initiate and support oncogenesis, the HR HPV protein E6 functions to dysregulate normal cellular processes. HR HPV type 16 E6 (16E6) has previously been shown to bind cellular proteins in order to transcriptionally activate genes and to target regulatory proteins for degradation. We have identified an additional functional model for 16E6. First, 16E6 binds to cellular RNA processing and binding proteins, specifically cytoplasmic poly(A) binding proteins (PABPCs) and NFX1-123. Then, 16E6 hijacks those proteins' functions to post-transcriptionally regulate cellular immortalization, growth, and differentiation genes and pathways in keratinocytes. In this review, we have highlighted studies that introduce this new model of 16E6 functionality. Understanding ways in which HR HPV dysregulates cellular processes-particularly at the level of post-transcriptional gene regulation-presents new ways to consider mechanisms underlying DNA tumor virus function and new areas for therapeutic target development in HPV-associated cancers.

TLR9 in the Human Papilloma Virus Infections: Friend or Foe?

Immune system plays dual roles during human papilloma virus (HPV) infections, from defense against the virus to induction or stimulation of the HPV-related cancers. It appears that various differences within the immune-related genes and the functions of the immunological parameters of the patients are the main factors responsible for the roles played by immune system during HPV infections. Toll-like receptors (TLRs) play key roles in the recognition of viruses and activation of immune responses. The molecules also can alter the target cell intracellular signaling and may participate in the transformation of the infected cells. TLR9 is the unique intracellular member of TLRs that recognize foreign DNA, including viral DNA. Thus, TLR9 may play significant roles in the defense against HPV and its related cancers. This review article discusses TLR9 antiviral and pathological roles during HPV infection.