Degradation of the retinoblastoma tumor suppressor by the human papillomavirus type 16 E7 oncoprotein is important for functional inactivation and is separable from proteasomal degradation of E7

Comprehensive insights into human papillomavirus and cervical cancer: Pathophysiology, screening, and vaccination strategies

This article provides an in-depth review of the Human Papillomavirus (HPV), a predominant etiological factor in cervical cancer, exploring its pathophysiology, epidemiology, and mechanisms of oncogenesis. We examine the role of proteins, DNA methylation markers, and non-coding RNAs as predictive biomarkers in cervical cancer, highlighting their potential in refining diagnostic and prognostic practices. The evolution and efficacy of cervical cancer screening methods, including the Papanicolaou smear, HPV testing, cytology and HPV test, and colposcopy techniques, are critically analyzed. Furthermore, the article delves into the current landscape and future prospects of prophylactic HPV vaccines and therapeutic vaccines, underscoring their significance in the prevention and potential treatment of HPV-related diseases. This comprehensive review aims to synthesize recent advances and ongoing challenges in the field, providing a foundation for future research and clinical strategies in the prevention and management of cervical cancer.

Therapeutic Strategies in Advanced Cervical Cancer Detection, Prevention and Treatment

Cervical cancer is ranked the fourth most common cause of cancer related deaths amongst women. The situation is particularly dire in low to lower middle-income countries. It continues to affect these countries due to poor vaccine coverage and screening. Cervical cancer is mostly detected in the advanced stages leading to poor outcomes. This review focuses on the progress made to date to improve early detection and targeted therapy using both circulating RNA. Vaccine has played a major role in cervical cancer control in vaccinated young woman in mainly developed countries yet in low-income countries with challenges of 3 dose vaccination affordability, cervical cancer continues to be the second most deadly amongst women. In this review, we show the progress made in reducing cervical cancer using vaccination that in combination with other treatments that might improve survival in cervical cancer. We further show with both miRNA and siRNA that targeted therapy and specific markers might be ideal for early detection of cervical cancer in low-income countries. These markers are either upregulated or down regulated in cancer providing clue to the stage of the cancer.

MicroRNAs and human viral diseases: A focus on the role of microRNA-29

The viral replication can impress through cellular miRNAs. Indeed, either the antiviral responses or the viral infection changes through cellular miRNAs resulting in affecting many regulatory signaling pathways. One of the microRNA families that is effective in human cancers, diseases, and viral infections is the miR-29 family. Members of miR-29 family are effective in different viral infections as their roles have appeared in regulation of immunity pathways either in innate immunity including interferon and inflammatory pathways or in adaptive immunity including activation of T-cells and antibodies production. Although miR-29a affects viral replication by suppressing antiviral responses, it can inhibit the expression of viral mRNAs via binding to their 3'UTR. In the present work, we discuss the evidence related to miR-29a and viral infection through host immunity regulation. We also review roles of other miR-29 family members by focusing on their role as biomarkers for diagnosing and targets for viral diseases management.

Assessment of malignant potential for HPV types 16, 52, and 58 in the uterine cervix within a Korean cohort

High-risk human papillomavirus (HR-HPV) is the primary carcinogen in uterine cervical carcinoma. While genotype-specific carcinogenic risks have been extensively studied in Western populations, data from Korean are sparse. This study evaluates the malignant potential of the three most prevalent HR-HPVs in Korea: HPV16, HPV52, and HPV58. We analyzed 230 patients who underwent cervical conization and had been tested for HPV within a year prior to the procedure, excluding those with multiple infections. This analysis was confined to patients with single HPV infections and assessed outcomes of CIN3+, which includes carcinoma in situ (CIN3) and invasive carcinoma. The incidence of invasive cervical cancer was 6.7% for HPV16, 1.7% for HPV52, and 2.0% for HPV58; however, these differences were not statistically significant (p = 0.187). The rate of CIN3+ for HPV16, HPV52, and HPV58 were 70.6%, 51.7%, and 58.8%, respectively. Despite the small sample size, which may limit the robustness of statistical analysis, the data suggest a higher observed risk with HPV16. These findings highlight the need for vigilant clinical management tailored to specific HPV genotypes and support the implementation of a nine-valent vaccine in Korea. Physicians should be aware of these genotype-specific risks when treating patients.

HPV oncogenes expressed from only one of multiple integrated HPV DNA copies drive clonal cell expansion in cervical cancer

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.

Bioinformatics analysis of photoexcited natural flavonoid glycosides as the inhibitors for oropharyngeal HPV oncoproteins

The presence of oropharyngeal human papillomavirus (HPV)-18 E6 and E7 oncoproteins is highly significant in the progression of oropharyngeal cancer. Natural flavonoid compounds have potential as photosensitizers for light-activated antimicrobial therapy against HPV-associated oropharyngeal cancer. This study evaluated five natural flavonoid glycosides including Fisetin, Kaempferol, Morin, Myricetin, and Quercetin as photosensitizers against HPV-18 E6 and E7 oncoproteins using computational methods. After obtaining the amino acid sequences of HPV-18 E6 and E7, various tools were used to predict and verify their properties. The PubChem database was then examined to identify potential natural flavonoid glycosides, followed by predictions of their drug-likeness and ADMET properties. Subsequently, molecular docking was conducted to enhance the screening accuracy and to gain insights into the interactions between the natural compounds and the active sites of HPV-18 E6 and E7 oncoproteins. The protein structures of E6 and E7 were predicted and validated to be reliable. The results of molecular docking demonstrated that Kaempferol exhibited the highest binding affinity to both E6 and E7. All compounds satisfied Lipinski's rules of drug-likeness, except Myricetin. They showed high absorption, distribution volume and similar ADMET profiles with no toxicity. In summary, natural flavonoid glycosides, especially Kaempferol, show potential as photosensitizers for antimicrobial photodynamic therapy against HPV-associated oropharyngeal cancer through inhibition of E6 and E7 oncoproteins. These findings provide insights into the development of novel therapeutic strategies based on antimicrobial photodynamic therapy.

Impact of HPV strains on molecular mechanisms of cervix cancer

PURPOSE

Cervical cancer accounts for a high number of deaths worldwide. Risk factors are extensive for cervix cancer but Human papillomavirus (HPV) plays a prime role in its development. Different strains of HPV are prevalent globally, which show different grades of mortality and morbidity among women. This study is planned to evaluate the molecular mechanism of different strains of HPV infection and progression leading to cervix cancer.

METHODS

This review includes different research articles on cervix cancer progression reported from India and all over the world.

RESULTS

HPV 16 and 18 are prevalent strains using heparan sulfate-independent and dependent pathways for viral replication inside the cell. It also uses transcription mechanisms through NF-kappa B, FOXA-1, and AP-1 genes while strains like HPV-35, 45, and 52 are also predominant in India, which showed a very slow mechanism of progression due to which mortality rate is low after their infection with these strains.

CONCLUSION

HPV uses E6 and E7 proteins which activate NF-kappa B and AP-1 pathway which suppresses the tumor suppressor gene and activates cytokine production, causing inflammation and leading to a decrease in apoptosis due to Caspase-3 activation. In contrast, the E7 protein involves HOXA genes and decreases apoptotic factors due to which mortality and incidence rates are low in viruses that use E7 motifs. Some HPV strains employ the cap-dependent pathway, which is also associated with lower mortality and infection rates.

MmuPV1 E6 induces cell proliferation and other hallmarks of cancer

IMPORTANCE

The Mus musculus papillomavirus 1 (MmuPV1) E6 and E7 proteins are required for MmuPV1-induced disease. Our understanding of the activities of MmuPV1 E6 has been based on affinity purification/mass spectrometry studies where cellular interacting partners of MmuPV1 E6 were identified, and these studies revealed that MmuPV1 E6 can inhibit keratinocyte differentiation through multiple mechanisms. We report that MmuPV1 E6 encodes additional activities including the induction of proliferation, resistance to density-mediated growth arrest, and decreased dependence on exogenous growth factors. Proteomic and transcriptomic analyses provided evidence that MmuPV1 E6 increases the expression and steady state levels of a number of cellular proteins that promote cellular proliferation and other hallmarks of cancer. These results indicate that MmuPV1 E6 is a major driver of MmuPV1-induced pathogenesis.

Regulatory Effect of Ficus carica Latex on Cell Cycle Progression in Human Papillomavirus-Positive Cervical Cancer Cell Lines: Insights from Gene Expression Analysis

Cervical cancer presents a significant global health concern with high-risk human papillomaviruses (HPVs) identified as the main cause of this cancer. Although current treatment methods for cervical cancer can eliminate lesions, preventing metastatic spread and minimizing tissue damage remain a major challenge. Therefore, the development of a safer and innovative therapeutic approach is of the utmost importance. Natural products like fig latex, derived from the Ficus carica tree, have demonstrated promising anti-cancer properties when tested on cervical cancer cell lines. However, the specific mechanisms by which fig latex exerts its effects are still unknown. In this study, we conducted RNA-Seq analysis to explore how fig latex may counteract carcinogenesis in HPV-positive cervical cancer cell lines, namely, CaSki (HPV type 16-positive) and HeLa (HPV type 18-positive). Our results from this investigation indicate that fig latex influences the expression of genes associated with the development and progression of cervical cancer, including pathways related to "Nonsense-Mediated Decay (NMD)", "Cell Cycle regulation", "Transcriptional Regulation by TP53", and "Apoptotic Process". This selective impact of fig latex on cancer-related pathways suggests a potential novel therapeutic approach for HPV-related cervical cancer.

Identification and characterisation of novel potential phospho-acceptor sites in HPV-16 E7

Several studies have described functional regulation of high-risk human papillomaviruses (HPVs), E6 and E7 oncoproteins via posttranslational modifications (PTMs). However, how these PTMs modulate the activity of E6 and E7, particularly in their targeting of cellular proteins, is not completely understood. In this study, we show that HPV16 E7 can be phosphorylated by casein kinase I (CKI) and glycogen synthase kinase 3 (GSK3). This principal phosphorylation occurs at threonine residues 5 and 7 with a more minor role for residues 19-20 in the N-terminal region of 16 E7. Intriguingly, whilst mutational analyses suggest that residues 5 and 7 may be dispensable for the transformation of primary baby rat kidney cells by E7, intact residues 19 and 20 are required. Furthermore, negative charges at these residues (TT19-20DD) enhance the pRb-E7 interaction and cells display increased proliferation and invasion capacities. Using a proteomic approach with a phosphorylated peptide spanning the TT19-20 region of HPV16 E7, we have identified a panel of new, phospho-specific E7 interacting partners. These results shed new light on the complexity of N-terminal phosphorylation of E7 and how this can contribute towards expanding the repertoire of E7 targeted pathways.

Targeted inhibition of BET proteins in HPV-16 associated head and neck squamous cell carcinoma reveals heterogeneous transcription response

Integrated human papillomavirus (HPV-16) associated head and neck squamous cell carcinoma (HNSCC) tumors have worse survival outcomes compared to episomal HPV-16 HNSCC tumors. Therefore, there is a need to differentiate treatment for HPV-16 integrated HNSCC from other viral forms. We analyzed TCGA data and found that HPV+ HNSCC expressed higher transcript levels of the bromodomain and extra terminal domain (BET) family of transcriptional coregulators. However, the mechanism of BET protein-mediated transcription of viral-cellular genes in the integrated viral-HNSCC genomes needs to be better understood. We show that BET inhibition downregulates E6 significantly independent of the viral transcription factor, E2, and there was overall heterogeneity in the downregulation of viral transcription in response to the effects of BET inhibition across HPV-associated cell lines. Chemical BET inhibition was phenocopied with the knockdown of BRD4 and mirrored downregulation of viral E6 and E7 expression. Strikingly, there was heterogeneity in the reactivation of p53 levels despite E6 downregulation, while E7 downregulation did not alter Rb levels significantly. We identified that BET inhibition directly downregulated c-Myc and E2F expression and induced CDKN1A expression. Overall, our studies show that BET inhibition provokes a G1-cell cycle arrest with apoptotic activity and suggests that BET inhibition regulates both viral and cellular gene expression in HPV-associated HNSCC.

Human papillomaviruses: Knowns, mysteries, and unchartered territories

There has been an explosion in the number of papillomaviruses that have been identified and fully sequenced. Yet only a minute fraction of these has been studied in any detail. Most of our molecular research efforts have focused on the E6 and E7 proteins of "high-risk," cancer-associated human papillomaviruses (HPVs). Interactions of the high-risk HPV E6 and E7 proteins with their respective cellular targets, the p53 and the retinoblastoma tumor suppressors, have been investigated in minute detail. Some have thus questioned if research on papillomaviruses remains an exciting and worthwhile area of investigation. However, fundamentally new insights on the biological activities and cellular targets of the high-risk HPV E6 and E7 proteins have been discovered and previously unstudied HPVs have been newly associated with human diseases. HPV infections continue to be an important cause of human morbidity and mortality and since there are no antivirals to combat HPV infections, research on HPVs should remain attractive to new investigators and biomedical funding agencies, alike.

Do Concurrent Multiple Infections with High-Risk HPVs Carry a More Malignant Potential than a Single Infection in the Uterine Cervix?

The high-risk human papillomavirus (HR-HPV) has been known as the most important carcinogen in uterine cervical carcinoma. However, there is limited evidence of the malignant potential of these concurrent multiple infections. This study included women who had undergone cervical conization. They underwent an HPV test by cervical swab within 12 months before the surgery. They were divided into two groups: one with a single infection with HR-HPV16 and the other with concurrent multiple infections with HR-HPVs, including genotype 16. Pathologic examination classified cases as CIS+ to assess and compare the malignant potential in both groups, including carcinoma in situ (CIS) and invasive carcinoma. Of the 220 patients infected with HR-HPV16, the single infection group consisted of 120 patients (54.5%), whereas the concurrent multiple infections consisted of 100 (45.5%) patients. The rates of HSIL were significantly higher in the concurrent multiple infection group. However, the odds ratio for CIS+ did not show a significant difference between both groups (1.417, 95% CI = 0.831-2.414, p = 0.200). The malignant potential was not significantly different between concurrent multiple infections with HR-HPVs, including 16, and a single infection with 16 in Korean women.

A small molecule targeting the interaction between human papillomavirus E7 oncoprotein and cellular phosphatase PTPN14 exerts antitumoral activity in cervical cancer cells

Human papillomavirus (HPV)-induced cancers still represent a major health issue for worldwide population and lack specific therapeutic regimens. Despite substantial advancements in anti-HPV vaccination, the incidence of HPV-related cancers remains high, thus there is an urgent need for specific anti-HPV drugs. The HPV E7 oncoprotein is a major driver of carcinogenesis that acts by inducing the degradation of several host factors. A target is represented by the cellular phosphatase PTPN14 and its E7-mediated degradation was shown to be crucial in HPV oncogenesis. Here, by exploiting the crystal structure of E7 bound to PTPN14, we performed an in silico screening of small-molecule compounds targeting the C-terminal CR3 domain of E7 involved in the interaction with PTPN14. We discovered a compound able to inhibit the E7/PTPN14 interaction in vitro and to rescue PTPN14 levels in cells, leading to a reduction in viability, proliferation, migration, and cancer-stem cell potential of HPV-positive cervical cancer cells. Mechanistically, as a consequence of PTPN14 rescue, treatment of cancer cells with this compound altered the Yes-associated protein (YAP) nuclear-cytoplasmic shuttling and downstream signaling. Notably, this compound was active against cervical cancer cells transformed by different high-risk (HR)-HPV genotypes indicating a potential broad-spectrum activity. Overall, our study reports the first-in-class inhibitor of E7/PTPN14 interaction and provides the proof-of-principle that pharmacological inhibition of this interaction by small-molecule compounds could be a feasible therapeutic strategy for the development of novel antitumoral drugs specific for HPV-associated cancers.

Evidence for direct interaction between the oncogenic proteins E6 and E7 of high-risk human papillomavirus (HPV)

Human papillomaviruses (HPVs) are DNA tumor viruses that infect mucosal and cutaneous epithelial cells of more than 20 vertebrates. High-risk HPV causes about 5% of human cancers worldwide, and the viral proteins E6 and E7 promote carcinogenesis by interacting with tumor suppressors and interfering with many cellular pathways. As a consequence, they immortalize cells more efficiently in concert than individually. So far, the networks of E6 and E7 with their respective cellular targets have been studied extensively but independently. However, we hypothesized that E6 and E7 might also interact directly with each other in a novel interaction affecting HPV-related carcinogenesis. Here, we report a direct interaction between E6 and E7 proteins from carcinogenic HPV types 16 and 31. We demonstrated this interaction via cellular assays using two orthogonal methods: coimmunoprecipitation and flow cytometry-based FRET assays. Analytical ultracentrifugation of the recombinant proteins revealed that the stoichiometry of the E6/E7 complex involves two E7 molecules and two E6 molecules. In addition, fluorescence polarization showed that (I) E6 binds to E7 with a similar affinity for HPV16 and HPV31 (in the same micromolar range) and (II) that the binding interface involves the unstructured N-terminal region of E7. The direct interaction of these highly conserved papillomaviral oncoproteins may provide a new perspective for studying HPV-associated carcinogenesis and the overall viral life cycle.

Integrative Analysis of a Large Real-World Cohort of Small Cell Lung Cancer Identifies Distinct Genetic Subtypes and Insights into Histologic Transformation

Small cell lung cancer (SCLC) is a recalcitrant neuroendocrine carcinoma with dismal survival outcomes. A major barrier in the field has been the relative paucity of human tumors studied. Here we provide an integrated analysis of 3,600 "real-world" SCLC cases. This large cohort allowed us to identify new recurrent alterations and genetic subtypes, including STK11-mutant tumors (1.7%) and TP53/RB1 wild-type tumors (5.5%), as well as rare cases that were human papillomavirus-positive. In our cohort, gene amplifications on 4q12 are associated with increased overall survival, whereas CCNE1 amplification is associated with decreased overall survival. We also identify more frequent alterations in the PTEN pathway in brain metastases. Finally, profiling cases of SCLC containing oncogenic drivers typically associated with NSCLC demonstrates that SCLC transformation may occur across multiple distinct molecular cohorts of NSCLC. These novel and unsuspected genetic features of SCLC may help personalize treatment approaches for this fatal form of cancer.

SIGNIFICANCE

Minimal changes in therapy and survival outcomes have occurred in SCLC for the past four decades. The identification of new genetic subtypes and novel recurrent mutations as well as an improved understanding of the mechanisms of transformation to SCLC from NSCLC may guide the development of personalized therapies for subsets of patients with SCLC. This article is highlighted in the In This Issue feature, p. 1501.

Interaction between Human Papillomavirus-Encoded E6 Protein and AurB Induces Cell Immortalization and Proliferation-A Potential Target of Intervention

The human papillomavirus E6 and E7 oncoproteins interact with a different subset of host proteins, leading to dysregulation of the apoptotic, cell cycle, and signaling pathways. In this study, we identified, for the first time, that Aurora kinase B (AurB) is a bona fide interacting partner of E6. We systematically characterized the AurB-E6 complex formation and its consequences in carcinogenesis using a series of in vitro and cell-based assays. We also assessed the efficacy of Aurora kinase inhibitors in halting HPV-mediated carcinogenesis using in vitro and in vivo models. We showed that AurB activity was elevated in HPV-positive cells, and this correlated positively with the E6 protein level. E6 interacted directly with AurB in the nucleus or mitotic cells. A previously unidentified region of E6, located upstream of C-terminal E6-PBM, was important for AurB-E6 complex formation. AurB-E6 complex led to reduced AurB kinase activity. However, the AurB-E6 complex increased the hTERT protein level and its telomerase activity. On the other hand, AurB inhibition led to the inhibition of telomerase activity, cell proliferation, and tumor formation, even though this may occur in an HPV-independent manner. In summary, this study dissected the molecular mechanism of how E6 recruits AurB to induce cell immortalization and proliferation, leading to the eventual cancer development. Our findings revealed that the treatment of AZD1152 exerted a non-specific anti-tumor effect. Hence, a continuous effort to seek a specific and selective inhibitor that can halt HPV-mediated carcinogenesis should be warranted.

Therapeutic efficacy of a VSV-GP-based human papilloma virus vaccine in a murine cancer model

Human papilloma virus (HPV) infections are associated with almost all cervical cancers and to a lower extend also with anogenital or oropharyngeal cancers. HPV proteins expressed in HPV-associated tumors are attractive antigens for cancer vaccination strategies as self-tolerance, which is associated with most endogenous tumor-associated antigens, does not need to be overcome. In this study, we generated a live attenuated cancer vaccine based on the chimeric vesicular stomatitis virus VSV-GP, which has previously proven to be a potent vaccine vector and oncolytic virus. Genes at an earlier position in the genome more to the 3' end are expressed stronger compared to genes located further downstream. By inserting an HPV16-derived antigen cassette consisting of E2, E6 and E7 into VSV-GP either at first (HPVp1) or fifth (HPVp5) position in VSV-GP's genome we aimed to analyze the effect of vaccine antigen position and consequently expression level on viral fitness, immunogenicity, and anti-tumoral efficacy in a syngeneic mouse tumor model. HPVp1 expressed higher amounts of HPV antigens compared to HPVp5 in vitro but had a slightly delayed replication kinetic which overall translated into increased HPV-specific T cell responses upon vaccination of mice. Immunization with both vectors protected mice in prophylactic and in therapeutic TC-1 tumor models with HPVp1 being more effective in the prophylactic setting. Taken together, VSV-GP is a promising candidate as therapeutic HPV vaccine and first position of the vaccine antigen in a VSV-derived vector seems to be superior to fifth position.

Aspergillus Species and Human Papillomavirus Infections in Epithelial Tumors of Nasal and Paranasal Cavities

Background: There are diverse lesions originating from the paranasal sinuses and nasal cavity. Tobacco use, alcohol consumption, and malnutrition have been identified to play a role in the development of head and neck carcinomas. Recently, fungi and viruses have been recognized as potential causes of nasal cavity and paranasal tumors. Objectives: This study aimed at specifying the prevalence of Aspergillus and human papillomavirus (HPV) infections in the epithelial tumors of nasal cavity and paranasal sinuses. Methods: In this cross-sectional study, 57 paraffin-embedded tissue samples of malignant and benign lesions of the paranasal sinuses and nasal cavity were evaluated for the presence of Aspergillus and HPV DNA by nested polymerase chain reaction (nPCR) technique with specific primers. Results: Despite the absence of angular hyphae (acute angle) of the fungus on histopathological slides, overall, 10 (17.54%) out of 57 paraffin-embedded samples were found to be positive for Aspergillus species. However, HPV-DNA was not found in any of the samples. Conclusions: Our data suggest that fungal infections (especially aspergillosis) as an etiological factor can be contributed to the development of sinonasal cancer and, therefore, they should be considered in the management of patients with sinonasal cancer. In addition, PCR can provide an alternative to culture-dependent identification methods.

Human papillomavirus in the setting of immunodeficiency: Pathogenesis and the emergence of next-generation therapies to reduce the high associated cancer risk

Human papillomavirus (HPV), a common sexually transmitted virus infecting mucosal or cutaneous stratified epithelia, is implicated in the rising of associated cancers worldwide. While HPV infection can be cleared by an adequate immune response, immunocompromised individuals can develop persistent, treatment-refractory, and progressive disease. Primary immunodeficiencies (PIDs) associated with HPV-related disease include inborn errors of GATA, EVER1/2, and CXCR4 mutations, resulting in defective cellular function. People living with secondary immunodeficiency (e.g. solid-organ transplants recipients of immunosuppression) and acquired immunodeficiency (e.g. concurrent human immunodeficiency virus (HIV) infection) are also at significant risk of HPV-related disease. Immunocompromised people are highly susceptible to the development of cutaneous and mucosal warts, and cervical, anogenital and oropharyngeal carcinomas. The specific mechanisms underlying high-risk HPV-driven cancer development in immunocompromised hosts are not well understood. Current treatments for HPV-related cancers include surgery with adjuvant chemotherapy and/or radiotherapy, with clinical trials underway to investigate the use of anti-PD-1 therapy. In the setting of HIV co-infection, persistent high-grade anal intraepithelial neoplasia can occur despite suppressive antiretroviral therapy, resulting in an ongoing risk for transformation to overt malignancy. Although therapeutic vaccines against HPV are under development, the efficacy of these in the setting of PID, secondary- or acquired- immunodeficiencies remains unclear. RNA-based therapeutic targeting of the HPV genome or mRNA transcript has become a promising next-generation therapeutic avenue. In this review, we summarise the current understanding of HPV pathogenesis, immune evasion, and malignant transformation, with a focus on key PIDs, secondary immunodeficiencies, and HIV infection. Current management and vaccine regimes are outlined in relation to HPV-driven cancer, and specifically, the need for more effective therapeutic strategies for immunocompromised hosts. The recent advances in RNA-based gene targeting including CRISPR and short interfering RNA (siRNA), and the potential application to HPV infection are of great interest. An increased understanding of both the dysregulated immune responses in immunocompromised hosts and of viral persistence is essential for the design of next-generation therapies to eliminate HPV persistence and cancer development in the most at-risk populations.

E6-Encoded by Cancer-Causing Human Papillomavirus Interacts with Aurora Kinase A To Promote HPV-Mediated Carcinogenesis

The expression of human papillomavirus (HPV) oncoproteins perturbed multiple cellular events of the host cells, leading to the formation of cancer phenotypes. Our current and previous studies indicated that Aurora kinase A (AurA), a mitotic regulator that is often aberrantly expressed in human cancers, is preferentially bound to E6-encoded by cancer-causing HPV. AurA is believed to be important for the proliferation and survival of HPV-positive cells. Nonetheless, the interaction between AurA and E6, and the mechanism of how this association is involved in carcinogenesis, have not been elucidated clearly. Hence, we performed a series of biochemical assays to characterize the AurA-E6 association and complex formation. We found the C-terminus of E6, upstream of the PDZ binding motif of E6, is important to forming the AurA-E6 complex in the nucleus. We also showed that the expression level of E6 corresponded positively with AurA expression. Meanwhile, the functional consequences of the AurA-E6 association to AurA kinase function and host cellular events were also delineated. Intriguingly, we revealed that AurA-E6 association regulated the expression of cyclin E and phosphor-Histone H3, which are involved in G1/S and mitotic phases of the cell cycle, respectively. Depletion of AurA also reduced the invasive ability of HPV-positive cells. AurA inhibition may not be sufficient to reduce the oncogenic potential exerted by E6. Altogether, our study unleashed the mechanism of how HPVE6 deploy AurA to promote cancer phenotypes, particularly through dysregulation of cell cycle checkpoints and suggests that the AurA-E6 complex possesses a therapeutic value. IMPORTANCE We unveiled the mechanism of how HPV employs Aurora kinase A (AurA) of host cells to exert its oncogenic capability synergistically. We systematically characterized the mode of interaction between E6-encoded by cancer-causing HPV and AurA. Then, we delineated the consequences of AurA-E6 complex formation on AurA kinase function and changes to cellular events at molecular levels. Using a cell-based approach, we unleashed that disruption of AurA-E6 association can halt cancer phenotype exhibited by HPV-positive cancer cells. Our findings are vital for the designing of state-of-the-art therapies for HPV-associated cancers.

Green Tea in Reproductive Cancers: Could Treatment Be as Simple?

Green tea originates from the tea plant Camellia sinensis and is one of the most widely consumed beverages worldwide. Green tea polyphenols, commonly known as catechins, are the major bioactive ingredients and account for green tea's unique health benefits. Epigallocatechin-3-gallate (EGCG), is the most potent catechin derivative and has been widely studied for its pro- and anti-oxidative effects. This review summarizes the chemical and chemopreventive properties of green tea in the context of female reproductive cancers. A comprehensive search of PubMed and Google Scholar up to December 2022 was conducted. All original and review articles related to green tea or EGCG, and gynecological cancers published in English were included. The findings of several in vitro, in vivo, and epidemiological studies examining the effect of green tea on reproductive cancers, including ovarian, cervical, endometrial, and vulvar cancers, are presented. Studies have shown that this compound targets specific receptors and intracellular signaling pathways involved in cancer pathogenesis. The potential benefits of using green tea in the treatment of reproductive cancers, alone or in conjunction with chemotherapeutic agents, are examined, shedding light on new therapeutic strategies for the management of female reproductive cancers.

HPV-16 E7 Interacts with the Endocytic Machinery via the AP2 Adaptor μ2 Subunit

Human papillomavirus (HPV) E7 plays a major role in HPV-induced malignancy, perturbing cell cycle regulation, and driving cell proliferation. Major targets of cancer-causing HPV E7 proteins are the pRB family of tumor suppressors, which E7 targets for proteasome-mediated degradation and whose interaction is promoted through an acidic patch, downstream of the LXCXE motif in E7, that is subject to phosphorylation by casein kinase II (CKII). In this study we show that HPV-16 E7 targets the AP2-complex, which plays a critical role in cargo recognition in clathrin-mediated endocytosis. Intriguingly, HPV-16 E7 contains a specific amino acid sequence for AP2 recognition, and this overlaps the pRb LXCXE recognition sequence but involves completely different amino acid residues. HPV-16 E7 does this by binding to the AP2-μ2 adaptor protein subunit via residues 25-YEQL-28 within the LXCXE motif. Point mutations at Y25 within 22-LYCYE-26 suggest that the interaction of E7 with AP2-μ2 is independent from pRB binding. In cells, this interaction is modulated by acidic residues downstream of LXCXE, with the binding being facilitated by CKII-phosphorylation of the serines at positions 31 and 32. Finally, we also show that association of HPV-16 E7 with the AP2 adaptor complex can contribute to cellular transformation under low-nutrient conditions, which appears to be mediated, in part, through inhibition of AP2-mediated internalization of epidermal growth factor receptor (EGFR). This indicates that E7 can modulate endocytic transport pathways, with one such component, EGFR, most likely contributing toward the ability of E7 to induce cell transformation and malignancy. These studies define a new and unexpected role for HPV-16 E7 in targeting clathrin-mediated endocytosis. IMPORTANCE Despite being a very small protein, HPV-E7 has a wide range of functions within the infected cell, many of which can lead to cell transformation. High-risk HPV-E7 deregulates the function of many cellular proteins, perturbing cellular homeostasis. We show that a novel target of HPV-E7 is the clathrin-adaptor protein 2 complex (AP2) μ2 subunit, interacting via residues within E7's pRB-binding region. Mutational studies show that an AP2 recognition motif is present in the CR2 region and is conserved in >50 HPV types, suggesting a common function for this motif in HPV biology. Mutational analysis suggests that this motif is important for cellular transformation, potentially modulating endocytosis of growth factor receptors such as EGFR, and thus being a novel activity of E7 in modulating clathrin-mediated endocytosis and cargo selection. This study has important implications for the molecular basis of E7 function in modulating protein trafficking at the cell surface.

The Four Homeostasis Knights: In Balance upon Post-Translational Modifications

A cancer outcome is a multifactorial event that comes from both exogenous injuries and an endogenous predisposing background. The healthy state is guaranteed by the fine-tuning of genes controlling cell proliferation, differentiation, and development, whose alteration induces cellular behavioral changes finally leading to cancer. The function of proteins in cells and tissues is controlled at both the transcriptional and translational level, and the mechanism allowing them to carry out their functions is not only a matter of level. A major challenge to the cell is to guarantee that proteins are made, folded, assembled and delivered to function properly, like and even more than other proteins when referring to oncogenes and onco-suppressors products. Over genetic, epigenetic, transcriptional, and translational control, protein synthesis depends on additional steps of regulation. Post-translational modifications are reversible and dynamic processes that allow the cell to rapidly modulate protein amounts and function. Among them, ubiquitination and ubiquitin-like modifications modulate the stability and control the activity of most of the proteins that manage cell cycle, immune responses, apoptosis, and senescence. The crosstalk between ubiquitination and ubiquitin-like modifications and post-translational modifications is a keystone to quickly update the activation state of many proteins responsible for the orchestration of cell metabolism. In this light, the correct activity of post-translational machinery is essential to prevent the development of cancer. Here we summarize the main post-translational modifications engaged in controlling the activity of the principal oncogenes and tumor suppressors genes involved in the development of most human cancers.

HPV 16 E7 alters translesion synthesis signaling

A subset of human papillomaviruses (HPVs) are the cause of virtually every cervical cancer. These so-called "high-risk" HPVs encode two major oncogenes (HPV E6 and E7) that are necessary for transformation. Among "high-risk" HPVs, HPV16 causes most cervical cancers and is often used as a representative model for oncogenic HPVs. The HPV16 E7 oncogene facilitates the HPV16 lifecycle by binding and destabilizing RB, which ensures the virus has access to cellular replication machinery. RB destabilization increases E2F1-responsive gene expression and causes replication stress. While HPV16 E6 mitigates some of the deleterious effects associated with this replication stress by degrading p53, cells undergo separate adaptations to tolerate the stress. Here, we demonstrate that this includes the activation of the translesion synthesis (TLS) pathway, which prevents replication stress from causing replication fork collapse. We show that significantly elevated TLS gene expression is more common in cervical cancers than 15 out of the 16 the other cancer types that we analyzed. In addition to increased TLS protein abundance, HPV16 E7 expressing cells have a reduced ability to induct a critical TLS factor (POLη) in response to replication stress-inducing agents. Finally, we show that increased expression of at least one TLS gene is associated with improved survival for women with cervical cancer.

Repression of Memo1, a Novel Target of Human Papillomavirus Type 16 E7, Increases Cell Proliferation in Cervical Cancer Cells

Human papillomavirus (HPV)-induced carcinogenesis is associated with unregulated expression of the oncoproteins E6 and E7. HPV E7 is a viral protein that lacks enzymatic activity; however, it can target several cellular proteins to induce cell transformation and promote uncontrolled proliferation. Although several E7 targets have been described, there are still gaps in the understanding of how this oncoprotein drives cells toward malignancy. Here, using a small HPV type 16 (HPV16) E7 peptide in a proteomic approach, we report Memo1 as a new E7 binding partner, interacting through the aspartic and glutamic acid residues (E80 and D81) in the C-terminal region of HPV16 E7. Furthermore, we demonstrate that HPV16 E7 targets Memo1 for proteasomal degradation through a Cullin2-dependent mechanism. In addition, we show that overexpression of Memo1 decreases cell transformation and proliferation and that reduction of Memo1 levels correlate with activation of Akt and an increase in invasion of HPV-positive cervical cancer cell lines. Our results show a novel HPV E7 interacting partner and describe novel functions of Memo1 in the context of HPV-induced malignancy. IMPORTANCE Although numerous targets have been reported to interact with the HPV E7 oncoprotein, the mechanisms involved in HPV-induced carcinogenesis and the maintenance of cell transformation are still lacking. Here, through pulldown assays using a peptide encompassing the C-terminal region of HPV16 E7, we report Memo1 as a novel E7 interactor. High levels of Memo1 correlated with reduced cell proliferation and, concordantly, knockdown of Memo1 resulted in Akt activation in HPV-positive cell lines. These results highlight new mechanisms used by HPV oncoproteins to modulate proliferation pathways in cervical cancer cells and increase our understanding of the link between Memo1 protein and cancer.

Regulation of HPV E7 Stability by E6-Associated Protein (E6AP)

High-risk human papillomaviruses (HPVs) are responsible for most human cervical cancers, and uncontrolled expression of the two key viral oncoproteins, E6 and E7, stimulates the induction of carcinogenesis. Previous studies have shown that both E6 and E7 are closely associated with different components of the ubiquitin proteasome pathway, including several ubiquitin ligases. Most often these are utilized to target cellular substrates for proteasome-mediated degradation, but in the case of E6, the E6AP ubiquitin ligase plays a critical role in controlling E6 stability. We now show that knockdown of E6AP in HPV-positive cervical cancer-derived cells causes a marked decrease in E7 protein levels. This is due to a decrease in the E7 half-life and occurs in a proteasome-dependent manner. In an attempt to define the underlying mechanism, we show that E7 can also associate with E6AP, albeit in a manner different from that of E6. In addition, we show that E6AP-dependent stabilization of E7 also leads to an increase in the degradation of E7's cellular target substrates. Interestingly, ectopic overexpression of E6 oncoprotein results in lower levels of E7 protein through sequestration of E6AP. We also show that increased E7 stability in the presence of E6AP increases the proliferation of the cervical cancer-derived cell lines. These results demonstrate a surprising interplay between E6 and E7, in a manner which is mediated by the E6AP ubiquitin ligase. IMPORTANCE This is the first demonstration that E6AP can directly help stabilize the HPV E7 oncoprotein, in a manner similar to that observed with HPV E6. This redefines how E6 and E7 can cooperate and potentially modulate each other's activity and further highlights the essential role played by E6AP in the viral life cycle and malignancy.

CIGB-300 Peptide Targets the CK2 Phospho-Acceptor Domain on Human Papillomavirus E7 and Disrupts the Retinoblastoma (RB) Complex in Cervical Cancer Cells

CIGB-300 is a clinical-grade anti-Protein Kinase CK2 peptide, binding both its substrate’s phospho-acceptor site and the CK2α catalytic subunit. The cyclic p15 inhibitory domain of CIGB-300 was initially selected in a phage display library screen for its ability to bind the CK2 phospho-acceptor domain ofHPV-16 E7. However, the actual role of this targeting in CIGB-300 antitumoral mechanism remains unexplored. Here, we investigated the physical interaction of CIGB-300 with HPV-E7 and its impact on CK2-mediated phosphorylation. Hence, we studied the relevance of targeting E7 phosphorylation for the cytotoxic effect induced by CIGB-300. Finally, co-immunoprecipitation experiments followed by western blotting were performed to study the impact of the peptide on the E7–pRB interaction. Interestingly, we found a clear binding of CIGB-300 to the N terminal region of E7 proteins of the HPV-16 type. Accordingly, the in vivo physical interaction of the peptide with HPV-16 E7 reduced CK2-mediated phosphorylation of E7, as well as its binding to the tumor suppressor pRB. However, the targeting of E7 phosphorylation by CIGB-300 seemed to be dispensable for the induction of cell death in HPV-18 cervical cancer-derived C4-1 cells. These findings unveil novel molecular clues to the means by which CIGB-300 triggers cell death in cervical cancer cells.

The Diagnostic Value of Circulating Cell-Free HPV DNA in Plasma from Cervical Cancer Patients

Circulating cell-free HPV DNA (ccfHPV DNA) may serve as a marker for cervical cancer. In this study, we used digital droplet PCR (ddPCR) to detect and quantify ccfHPV DNA in plasma from patients with HPV16- or HPV18-associated cervical cancer. Blood samples from 60 patients diagnosed with cervical cancer (FIGO IA1-IVA) at Aarhus or Odense University Hospital (June 2018 to March 2020) were collected prior to treatment, and patients were subdivided into an early stage (n = 30) and a late-stage subgroup (n = 30) according to disease stage. Furthermore, blood samples from eight women with HPV16- or 18-associated premalignant conditions (CIN3), and 15 healthy controls were collected. ddPCR was used to analyze plasma from all participants. ccfHPV DNA was detected in 19 late-stage patients (63.33%), 3 early stage patients (10.00%), and none of the CIN3 patients or controls. Quantitative evaluation showed significant correlations between ccfHPV DNA level and stage, tumor score, and tumor size. Thus, our results indicate that ccfHPV DNA may not be a useful marker for early detection of cervical cancer. However, for patients with advanced stage cervical cancer, ccfHPV DNA level represents a promising tool to establish tumor burden, making it useful for establishing treatment response and monitoring the disease.

Functional genomic analysis of CDK4 and CDK6 gene dependency across human cancer cell lines

Cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6) are key cell cycle regulators that are frequently dysregulated in human malignancies. CDK4/6 inhibitors are clinically approved for the treatment of hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer, but improved specificity and reduced toxicity might expand their use to other indications. Through analysis of publicly available genome-wide loss-of-function data combined with single and dual-targeting CRISPR assays, we found differential cell proliferation vulnerability of cell lines to either CDK4 deletion alone, CDK6 deletion alone, combined CDK4/CDK6 deletion, or neither. CDK6 expression was the best single predictor of CDK4 (negatively correlated) and CDK6 (positively correlated) dependencies in the cancer cell lines, with adenocarcinoma cell lines being more sensitive to CDK4 deletion and hematologic and squamous cancer cell lines being more sensitive to CDK6 deletion. RB-E2F signaling was confirmed as a main downstream node of CDK4/6 in these experiments as shown by the survival effects of RB1 deletion. Finally, we show in a subset of cancer cell lines not dependent on CDK4/6 that CDK2-CCNE1 is an important alternative dependency for cell proliferation. Together, our comprehensive data exploration and functional experiments delineate the landscape of pan-cancer CDK4/6 gene dependencies and define unique cancer cell populations that might be sensitive to CDK4-selective or CDK6-selective inhibitors.

Phytocompounds from the medicinal and dietary plants: Multi-target agents for cancer prevention and therapy

Cervical cancer is the fourth leading cause of cancer death among women worldwide. Due to cervical cancer's high incidence and mortality, there is an unmet demand for effective diagnostic, therapeutic, and preventive agents. At present, the preferred treatment strategies for advanced metastatic cervical cancer include surgery, radiotherapy, and chemotherapy. However, cervical cancer is gradually developing resistance to chemotherapy, thereby reducing its efficacy. Over the last several decades, phytochemicals, a general term for compounds produced from plants, have gained attention for their role in preventing cervical cancer. This role in cervical cancer prevention has garnered attention on the medicinal properties of fruits and vegetables. Phytochemicals are currently being evaluated for their ability to block proteins involved in carcinogenesis and chemoresistance against cervical cancer. Chemoresistance to cancer drugs like cisplatin, doxorubicin, and 5-fluorouracil has become a significant limitation of drug-based chemotherapy. However, the combination of cisplatin with other phytochemicals has been identified as a promising alternative to subjugate cisplatin resistance. Phytochemicals are promising chemo-preventive and chemotherapeutic agents as they possess antioxidant, anti-inflammatory, and anti-proliferative potential against many cancers, including cervical cancer. Furthermore, the ability of the phytochemicals to modulate cellular signaling pathways through up and down regulation of various proteins has been claimed for their therapeutic potential. Phytochemicals also display a wide range of biological functions, including cell cycle arrest, apoptosis induction, inhibition of invasion, and migration in cervical cancer cells. Numerous studies have revealed the critical role of different signaling proteins and their signaling pathways in the pathogenesis of cervical cancer. Here, we review the ability of several dietary phytochemicals to alter carcinogenesis by modulating various molecular targets.

Human Papillomaviruses as Infectious Agents in Gynecological Cancers. Oncogenic Properties of Viral Proteins

Human papillomaviruses (HPVs), which belong to the Papillomaviridae family, constitute a group of small nonenveloped double-stranded DNA viruses. HPV has a small genome that only encodes a few proteins, and it is also responsible for 5% of all human cancers, including cervical, vaginal, vulvar, penile, anal, and oropharyngeal cancers. HPV types may be classified as high- and low-risk genotypes (HR-HPVs and LR-HPVs, respectively) according to their oncogenic potential. HR-HPV 16 and 18 are the most common types worldwide and are the primary types that are responsible for most HPV-related cancers. The activity of the viral E6 and E7 oncoproteins, which interfere with critical cell cycle points such as suppressive tumor protein p53 (p53) and retinoblastoma protein (pRB), is the major contributor to HPV-induced neoplastic initiation and progression of carcinogenesis. In addition, the E5 protein might also play a significant role in tumorigenesis. The role of HPV in the pathogenesis of gynecological cancers is still not fully understood, which indicates a wide spectrum of potential research areas. This review focuses on HPV biology, the distribution of HPVs in gynecological cancers, the properties of viral oncoproteins, and the molecular mechanisms of carcinogenesis.

Targeted Next Generation Sequencing for Human Papillomavirus Genotyping in Cervical Liquid-Based Cytology Samples

At present, human papillomavirus (HPV) testing is replacing morphology-based cytology as the primary tool for cervical cancer screening in several countries. However, the HPV assays approved for screening lack detection for all but one of the possibly carcinogenic HPV types and do not genotype all included HPV types. This study demonstrates the use of a targeted HPV next generation sequencing (NGS) panel to detect and genotype all 25 carcinogenic, probably carcinogenic, and possibly carcinogenic HPV types as well as the low-risk types HPV6 and HPV11. The panel was validated using a cohort of 93 paired liquid-based cytology samples (general practitioner (GP)-collected cervical samples and cervico-vaginal self-samples (SS)). Overall, the targeted panel had a sensitivity (GP = 97.7%, SS = 92.1%) and specificity (GP = 98.0%, SS = 96.4%) similar to the commercial HPV assays, Cobas® 4800 HPV DNA test (Roche) and CLART® HPV4S assay (GENOMICA). Interestingly, of the samples that tested positive with the NGS panel, three (6.4%) of the GP-collected samples and four (9.1%) of the self-samples tested positive exclusively for HPV types only included in the NGS panel. Thus, targeted HPV sequencing has great potential to improve the HPV screening programs since, as shown here, it can identify additional HPV positive cases, cases with HPV integration, variants in the HPV genome, and which HPV type is dominant in multi-infected cases.

The Retinoblastoma Tumor Suppressor Is Required for the NUP98-HOXA9-Induced Aberrant Nuclear Envelope Phenotype

Chromosomal translocations involving the nucleoporin NUP98 gene are recurrently identified in leukemia; yet, the cellular defects accompanying NUP98 fusion proteins are poorly characterized. NUP98 fusions cause changes in nuclear and nuclear envelope (NE) organization, in particular, in the nuclear lamina and the lamina associated polypeptide 2α (LAP2α), a regulator of the tumor suppressor retinoblastoma protein (RB). We demonstrate that, for NUP98-HOXA9 (NHA9), the best-studied NUP98 fusion protein, its effect(s) on nuclear architecture largely depend(s) on RB. Morphological alterations caused by the expression of NHA9 are largely diminished in the absence of RB, both in human cells expressing the human papillomavirus 16 E7 protein and in mouse embryonic fibroblasts lacking RB. We further show that NHA9 expression associates with distinct histone modification. Moreover, the pattern of trimethylation of histone H3 lysine-27 is affected by NHA9, again in an RB-dependent manner. Our results pinpoint to an unexpected interplay between NUP98 fusion proteins and RB, which may contribute to leukemogenesis.

CRISPR/Cas9-based inactivation of human papillomavirus oncogenes E6 or E7 induces senescence in cervical cancer cells

Human papillomaviruses (HPVs) such as HPV16 and HPV18 can cause cancers of the cervix, anogenital and oropharyngeal sites. Continuous expression of the HPV oncoproteins E6 and E7 are essential for transformation and maintenance of cancer cells. Therefore, therapeutic targeting of E6 or E7 genes can potentially treat HPV-related cancers. Here we report that CRISPR/Cas9-based knockout of E6 or E7 can trigger cellular senescence in HPV18 immortalized HeLa cells. Specifically, E6 or E7-inactivated HeLa cells exhibited characteristic senescence markers like enlarged cell surface area, increased β-galactosidase expression and loss of lamin B1. Since E6 and E7 are bicistronic transcripts, inactivation of HPV18 E6 resulted in knockout of both E6 and E7 and increasing levels of p53/p21 and pRb/p21, respectively. Knockout of HPV18 E7 resulted in decreased E6 expression with activation of pRb/p21 pathway. Taken together, our study demonstrates cellular senescence as an alternative outcome of HPV oncogene inactivation by CRISPR/Cas9.

The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis

Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy-as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7-the not-so-good, the bad and the ugly-and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.

The Mus musculus Papillomavirus Type 1 E7 Protein Binds to the Retinoblastoma Tumor Suppressor: Implications for Viral Pathogenesis

The species specificity of papillomaviruses has been a significant roadblock for performing in vivo pathogenesis studies in common model organisms. The Mus musculus papillomavirus type 1 (MmuPV1) causes cutaneous papillomas that can progress to squamous cell carcinomas in laboratory mice. The papillomavirus E6 and E7 genes encode proteins that establish and maintain a cellular milieu that allows for viral genome synthesis and viral progeny synthesis in growth-arrested, terminally differentiated keratinocytes. The E6 and E7 proteins provide this activity by binding to and functionally reprogramming key cellular regulatory proteins. The MmuPV1 E7 protein lacks the canonical LXCXE motif that mediates the binding of multiple viral oncoproteins to the cellular retinoblastoma tumor suppressor protein, RB1. Our proteomic experiments, however, revealed that MmuPV1 E7 still interacts with RB1. We show that MmuPV1 E7 interacts through its C terminus with the C-terminal domain of RB1. Binding of MmuPV1 E7 to RB1 did not cause significant activation of E2F-regulated cellular genes. MmuPV1 E7 expression was shown to be essential for papilloma formation. Experimental infection of mice with MmuPV1 expressing an E7 mutant that is defective for binding to RB1 caused delayed onset, lower incidence, and smaller sizes of papillomas. Our results demonstrate that the MmuPV1 E7 gene is essential and that targeting noncanonical activities of RB1, which are independent of RB1's ability to modulate the expression of E2F-regulated genes, contribute to papillomavirus-mediated pathogenesis. IMPORTANCE Papillomavirus infections cause a variety of epithelial hyperplastic lesions, or warts. While most warts are benign, some papillomaviruses cause lesions that can progress to squamous cell carcinomas, and approximately 5% of all human cancers are caused by human papillomavirus (HPV) infections. The papillomavirus E6 and E7 proteins are thought to function to reprogram host epithelial cells to enable viral genome replication in terminally differentiated, normally growth-arrested cells. E6 and E7 lack enzymatic activities and function by interacting and functionally altering host cell regulatory proteins. Many cellular proteins that can interact with E6 and E7 have been identified, but the biological relevance of these interactions for viral pathogenesis has not been determined. This is because papillomaviruses are species specific and do not infect heterologous hosts. Here, we use a recently established mouse papillomavirus (MmuPV1) model to investigate the role of the E7 protein in viral pathogenesis. We show that MmuPV1 E7 is necessary for papilloma formation. The retinoblastoma tumor suppressor protein (RB1) is targeted by many papillomaviral E7 proteins, including cancer-associated HPVs. We show that MmuPV1 E7 can bind RB1 and that infection with a mutant MmuPV1 virus that expresses an RB1 binding-defective E7 mutant caused smaller and fewer papillomas that arise with delayed kinetics.

The Role of Viruses in Carcinogenesis and Molecular Targeting: From Infection to Being a Component of the Tumor Microenvironment

About a tenth of all cancers are caused by viruses or associated with viral infection. Recent global events including the coronavirus disease-2019 (COVID-19) pandemic means that human encounter with viruses is increased. Cancer development in individuals with viral infection can take many years after infection, demonstrating that the involvement of viruses in cancer development is a long and complex process. This complexity emanates from individual genetic heterogeneity and the many steps involved in cancer development owing to viruses. The process of tumorigenesis is driven by the complex interaction between several viral factors and host factors leading to the creation of a tumor microenvironment (TME) that is ideal and promotes tumor formation. Viruses associated with human cancers ensure their survival and proliferation through activation of several cellular processes including inflammation, migration, and invasion, resistance to apoptosis and growth suppressors. In addition, most human oncoviruses evade immune detection and can activate signaling cascades including the PI3K-Akt-mTOR, Notch and Wnt pathways associated with enhanced proliferation and angiogenesis. This expert review examines and synthesizes the multiple biological factors related to oncoviruses, and the signaling cascades activated by these viruses contributing to viral oncogenesis. In particular, I examine and review the Epstein-Barr virus, human papillomaviruses, and Kaposi's sarcoma herpes virus in a context of cancer pathogenesis. I conclude with a future outlook on therapeutic targeting of the viruses and their associated oncogenic pathways within the TME. These anticancer strategies can be in the form of, but not limited to, antibodies and inhibitors.

Metabolic Control by DNA Tumor Virus-Encoded Proteins

Viruses co-opt a multitude of host cell metabolic processes in order to meet the energy and substrate requirements for successful viral replication. However, due to their limited coding capacity, viruses must enact most, if not all, of these metabolic changes by influencing the function of available host cell regulatory proteins. Typically, certain viral proteins, some of which can function as viral oncoproteins, interact with these cellular regulatory proteins directly in order to effect changes in downstream metabolic pathways. This review highlights recent research into how four different DNA tumor viruses, namely human adenovirus, human papillomavirus, Epstein-Barr virus and Kaposi's associated-sarcoma herpesvirus, can influence host cell metabolism through their interactions with either MYC, p53 or the pRb/E2F complex. Interestingly, some of these host cell regulators can be activated or inhibited by the same virus, depending on which viral oncoprotein is interacting with the regulatory protein. This review highlights how MYC, p53 and pRb/E2F regulate host cell metabolism, followed by an outline of how each of these DNA tumor viruses control their activities. Understanding how DNA tumor viruses regulate metabolism through viral oncoproteins could assist in the discovery or repurposing of metabolic inhibitors for antiviral therapy or treatment of virus-dependent cancers.

The struggle of a good friend getting old: cellular senescence in viral responses and therapy

Cellular senescence is a state of stable cell cycle arrest associated with macromolecular alterations and secretion of pro-inflammatory cytokines and molecules. Senescence-associated phenotypes restrict damage propagation and activate immune responses, two essential processes involved in response to viral infections. However, excessive accumulation and persistence of senescent cells can become detrimental and promote pathology and dysfunctions. Various pharmacological interventions, including antiviral therapies, lead to aberrant and premature senescence. Here, we review the molecular mechanisms by which viral infections and antiviral therapy induce senescence. We highlight the importance of these processes in attenuating viral dissemination and damage propagation, but also how prematurely induced senescent cells can promote detrimental adverse effects in humans. We describe which sequelae due to viral infections and treatment can be partly due to excessive and aberrant senescence. Finally, we propose that pharmacological strategies which eliminate senescent cells or suppress their secretory phenotype could mitigate side effects and alleviate the onset of additional morbidities. These strategies can become extremely beneficial in patients recovering from viral infections or undergoing antiviral therapy.

The human papillomavirus oncoproteins: a review of the host pathways targeted on the road to transformation

Persistent infection with high-risk human papillomaviruses (HR-HPVs) is the causal factor in over 99 % of cervical cancer cases, and a significant proportion of oropharyngeal and anogenital cancers. The key drivers of HPV-mediated transformation are the oncoproteins E5, E6 and E7. Together, they act to prolong cell-cycle progression, delay differentiation and inhibit apoptosis in the host keratinocyte cell in order to generate an environment permissive for viral replication. The oncoproteins also have key roles in mediating evasion of the host immune response, enabling infection to persist. Moreover, prolonged infection within the cellular environment established by the HR-HPV oncoproteins can lead to the acquisition of host genetic mutations, eventually culminating in transformation to malignancy. In this review, we outline the many ways in which the HR-HPV oncoproteins manipulate the host cellular environment, focusing on how these activities can contribute to carcinogenesis.

Histone Deacetylase Inhibitors as Therapeutic Interventions on Cervical Cancer Induced by Human Papillomavirus

The role of epigenetic modifications on the carcinogenesis process has received a lot of attention in the last years. Among those, histone acetylation is a process regulated by histone deacetylases (HDAC) and histone acetyltransferases (HAT), and it plays an important role in epigenetic regulation, allowing the control of the gene expression. HDAC inhibitors (HDACi) induce cancer cell cycle arrest, differentiation, and cell death and reduce angiogenesis and other cellular events. Human papillomaviruses (HPVs) are small, non-enveloped double-stranded DNA viruses. They are major human carcinogens, being intricately linked to the development of cancer in 4.5% of the patients diagnosed with cancer worldwide. Long-term infection of high-risk (HR) HPV types, mainly HPV16 and HPV18, is one of the major risk factors responsible for promoting cervical cancer development. In vitro and in vivo assays have demonstrated that HDACi could be a promising therapy to HPV-related cervical cancer. Regardless of some controversial studies, the therapy with HDACi could target several cellular targets which HR-HPV oncoproteins could be able to deregulate. This review article describes the role of HDACi as a possible intervention in cervical cancer treatment induced by HPV, highlighting the main advances reached in the last years and providing insights for further investigations regarding those agents against cervical cancer.

Targeted next generation sequencing panel for HPV genotyping in cervical cancer

Cervical cancer are generally caused by a persistent infection with the oncogenic virus, HPV. Patients with HPV integration are more prone to develop cervical cancer than patients without integration. In this proof-of-concept study, we aimed to develop a sensitive method based on targeted amplicon based NGS for early and precise detection of high-risk HPV-genotypes that are highly associated with the development of cervical cancer. Furthermore, we aimed to investigate if amplicon based NGS allowed for HPV genotyping in cervical lesions and whether it could detect HPV integration. The cohort included a group of CIN3⁺ biopsies (n = 64), CIN2 samples that progressed (n = 5), CIN2 samples that regressed (n = 3), healthy controls (n = 10), and plasma samples (n = 10) from cervical cancer patients. Sequencing was performed using a custom targeted NGS panel designed to detect all 25 high-risk and probably high-risk and two low-risk HPV genotypes. The method was validated by the SPF₁₀ PCR-DEIA-LiPA₂₅ assay. In the cohort, the following HPV genotypes were identified: HPV-16, 18, 31, 33, 35, 45, 51, 52, 56, 58, and 59. When comparing the results from the SPF₁₀ PCR-DEIA-LiPA₂₅ analyses with the NGS analyses, there was close to a perfect agreement (K = 0.92) among the genotyped HPV types, while in the two cases with complete disagreement, a third assay was applied, and here the results of the NGS analyses were confirmed. Whereas multiple HPV types were detected by the SPF₁₀ PCR-DEIA-LiPA₂₅ assay, the NGS analysis clearly suggest that there is one predomentant HPV type. The NGS assay was capable of detecting HPV-16 in a previous false-negative sample classified by the INNO-LiPA assay, emphasizing the importance of including multiple regions of the HPV genome when genotyping. For the 10 plasma samples, our NGS analyses showed full agreement with the digital droplet PCR (ddPCR) analyses of HPV positive as well as negative plasma samples. Lastly, the custom panel was capable of detecting the integration of HPV-16 in the SiHa cell line. The HPV panel provides a highly cost-effective method for HPV detection and genotyping, as exemplified by a list price of around 75 € per sample. In conclusion, the current study demonstrates that targeted NGS is capable of detecting and genotyping HPV in both FFPE biopsies and plasma samples. This method provides for early diagnosis and prognosis of cervical cancer disease progression, thereby optimizing the potential of recovery and survival for these patients.

An increase of microRNA-16-1 is associated with the high proliferation of squamous intraepithelial lesions in the presence of the integrated state of HR-HPV in liquid cytology samples

Studies of cervical cancer (CC) have reported that microRNA-16-1 (miR-16-1), which is an oncomiR, is increased in the tissues and cell lines of CC. The aim of the present study was to investigate the association of miRNA-16-1 expression level with squamous cell carcinoma (SCC), the presence of squamous intraepithelial lesions (SIL) and the integration of high-risk human papillomavirus (HR-HPV) DNA. The current study analyzed 80 samples obtained from women by liquid-based cytology, which revealed that 20 were negative for SIL (NSIL) and without HPV, 20 were low-grade SIL (LSIL), 20 were high-grade SIL (HSIL), and 20 were diagnosed as SCC with HR-HPV. The genotyping of the viral DNA was conducted via an INNO-LiPA-HPV array, the expression of miR-16-1 was determined by reverse transcription-quantitative PCR, and the physical state of the HR-HPV was ascertained by in situ hybridization with amplification with tyramide. A total of eight HR-HPV genotypes were distinguished; the most frequent of these being HPV16, followed by multiple infection with HR-HPV (including HPV16). The mixed state of the HR-HPV was observed in 60 and 65% of LSIL and HSIL cases, respectively, while an integrated HR-HPV state was identified in 90% of cases with SCC. The expression level of miR-16-1 increased according to the grade of SIL, and cases with HSIL exhibited a significantly higher miR-16-1 expression level compared with women with NSIL (P<0.001; Table II). It can therefore be determined that the expression of miR-16-1 effects cellular proliferation, due to the viral integration of various HR-HPV genotypes in unique infection or in multiple infection. Thus, the overexpression of miR-16-1 could be monitored in women with LSIL, in order to discard a major lesion.

Human-Derived Model Systems in Gynecological Cancer Research

The human female reproductive tract (FRT) is a complex system that combines series of organs, including ovaries, fallopian tubes, uterus, cervix, vagina, and vulva; each of which possesses unique cellular characteristics and functions. This versatility, in turn, allows for the development of a wide range of epithelial gynecological cancers with distinct features. Thus, reliable model systems are required to better understand the diverse mechanisms involved in the regional pathogenesis of the reproductive tract and improve treatment strategies. Here, we review the current human-derived model systems available to study the multitude of gynecological cancers, including ovarian, endometrial, cervical, vaginal, and vulvar cancer, and the recent advances in the push towards personalized therapy.

HPV-Induced Oropharyngeal Cancer and the Role of the E7 Oncoprotein Detection via Brush Test

Background: High risk human papillomavirus (hr-HPV)-associated oropharyngeal cancers (OPCs) are characterized by significantly better therapy responses. In order to implement a de-escalated treatment strategy for this tumor entity, it is highly crucial to accurately distinguish HPV-associated OPCs from non-HPV-associated ones. Methods: In this prospective study, 56 patients with histologically confirmed OPC were evaluated. A commercially available sandwich ELISA test system was used for the detection of hr-HPV E7 oncoprotein targeting the genotypes 16, 18 and 45. Results were presented as optical density. Positivity for HPV DNA and p16 immunohistochemistry (IHC) was taken as the reference method. Results: E7 positivity was significantly associated with the reference method (p = 0.048). The sensitivity, specificity, positive predictive value and negative predictive value for the E7 oncoptotein was 60.9% (95% CI 38.5 to 80.3%), 66.7% (95% CI 46% to 83.5%), 64.2% (95% CI 49.4 to 77.4%) and 63.01% (95% CI 48.9–75.2%), respectively, for the cutoff provided by the manufacturer. Conclusions: We found a significant association between E7 oncoprotein detection and the currently used combination. We believe that the use of the ELISA based E7 antigen test could be a valuable addition in cases of ambiguous findings and may be used in combination with other techniques to distinguish between HPV-driven and non-HPV-driven OPCs. However, the low sensitivity of the assay coupled with the small sample size in our study may represent a limitation. We recommend that future larger studies elucidate the diagnostic value of the E7 brush test.

Proteasome-dependent protein quality control of the peroxisomal membrane protein Pxa1p

Peroxisomes are eukaryotic organelles that function in numerous metabolic pathways and defects in peroxisome function can cause serious developmental brain disorders such as adrenoleukodystrophy (ALD). Peroxisomal membrane proteins (PMPs) play a crucial role in regulating peroxisome function. Therefore, PMP homeostasis is vital for peroxisome function. Recently, we established that certain PMPs are degraded by the Ubiquitin Proteasome System yet little is known about how faulty/non-functional PMPs undergo quality control. Here we have investigated the degradation of Pxa1p, a fatty acid transporter in the yeast Saccharomyces cerevisiae. Pxa1p is a homologue of the human protein ALDP and mutations in ALDP result in the severe disorder ALD. By introducing two corresponding ALDP mutations into Pxa1p (Pxa1^MUT), fused to mGFP, we show that Pxa1^MUT-mGFP is rapidly degraded from peroxisomes in a proteasome-dependent manner, while wild type Pxa1-mGFP remains relatively stable. Furthermore, we identify a role for the ubiquitin ligase Ufd4p in Pxa1^MUT-mGFP degradation. Finally, we establish that inhibiting Pxa1^MUT-mGFP degradation results in a partial rescue of Pxa1p activity in cells. Together, our data demonstrate that faulty PMPs can undergo proteasome-dependent quality control. Furthermore, our observations may provide new insights into the role of ALDP degradation in ALD.

Human papillomavirus E7 binds Oct4 and regulates its activity in HPV-associated cervical cancers

Octamer binding transcription factor-4 (Oct4), is highly expressed in stem cells and has indispensable roles in pluripotency and cellular reprogramming. In contrast to other factors used for cellular reprogramming, a role for Oct4 outside embryonic stem cells has been elusive and highly controversial. Emerging evidence implicates Oct4 in the carcinogenic process, but the mechanism through which Oct4 may be functioning in cancers is not fully appreciated. Here, we provide evidence that Oct4 is expressed in human cervical cancer and this expression correlates with the presence of the human papillomavirus (HPV) oncogenes E6 and E7. Surprisingly, the viral oncogenes can complement exogenously provided Oct4 in reprogramming assays, providing functional validation for their ability to activate Oct4 transcription in Mouse Embryonic Fibroblasts (MEFs). To interrogate potential roles of Oct4 in cervical cancers we knocked-down Oct4 in HPV(+) (HeLa & CaSki) and HPV(-) (C33A) cervical cancer cell lines and found that Oct4 knockdown attenuated clonogenesis, only in the HPV(+) cells. More unexpectedly, cell proliferation and migration, were differentially affected in HPV(+) and HPV(-) cell lines. We provide evidence that Oct4 interacts with HPV E7 specifically at the CR3 region of the E7 protein and that introduction of the HPV oncogenes in C33A cells and human immortalised keratinocytes generates Oct4-associated transcriptional and phenotypic patterns, which mimic those seen in HPV(+) cells. We propose that a physical interaction of Oct4 with E7 regulates its activity in HPV(+) cervical cancers in a manner not seen in other cancer types.

Genome-Wide Transcriptome Analysis of Human Papillomavirus 16-Infected Primary Keratinocytes Reveals Subtle Perturbations Mostly due to E7 Protein Expression

It is established that the host cell transcriptomes of natural lesions, organotypic rafts, and human papillomavirus (HPV)-immortalized keratinocytes are altered in the presence of HPV genomes. However, the establishment of HPV-harboring cell lines requires selection and immortalization, which makes it impossible to distinguish between alterations directly induced by HPV or indirectly by the need for immortalization or selection. To address direct effects of HPV infection on the host cell transcriptome, we have used our recently established infection model that allows efficient infection of primary keratinocytes with HPV16 virions. We observed only a small set of genes to be deregulated at the transcriptional level at 7 days postinfection (dpi), most of which fall into the category regulated by pocket proteins pRb, p107, and p130. Furthermore, cell cycle genes were not deregulated in cells infected with a virus lacking E7 despite the presence of episomal genome and viral transcripts. These findings imply that the majority of transcriptional changes are due to the E7 protein impairing pocket protein function. Additional pathways, such as the Fanconi anemia-BRCA pathway, became perturbed only after long-term culturing of infected cells. When grown as organotypic raft cultures, keratinocytes infected with wild-type but not E7 mutant virus had perturbed transcriptional regulation of pathways previously identified in natural lesions and in rafts derived from immortalized keratinocytes. We conclude that the HPV infection model provides a valuable tool to distinguish immediate transcriptional alterations from those induced by persistent infection and the need for selection and immortalization.IMPORTANCE To establish infection and complete the viral life cycle, human papillomavirus (HPV) needs to alter the transcriptional program of host cells. Until recently, studies were restricted to keratinocyte-derived cell lines immortalized by HPV due to the lack of experimental systems to efficiently infect primary keratinocytes. Need for selection and immortalization made it impossible to distinguish between alterations induced by HPV and secondary adaptation due to selection and immortalization. With our recent establishment of an extracellular matrix (ECM)-to-cell transfer system allowing efficient infection of primary keratinocytes, we were able to identify transcriptional changes attributable to HPV16 infection. Most perturbed genes fall into the class of S-phase genes, which are regulated by pocket proteins. Indeed, infection with viruses lacking E7 abrogated most transcriptional changes. It is important to note that many transcriptional alterations thought to be important for the HPV life cycle are actually late events that may reflect immortalization and, possibly, disease progression.

Preclinical Activity of Ribociclib in Squamous Cell Carcinoma of the Head and Neck

Cell-cycle pathway impairments resulting in CDK4 and 6 activation are frequently observed in human papillomavirus (HPV)-negative squamous cell carcinoma of the head and neck (SCCHN). We investigated the activity of ribociclib, a CDK4/6 inhibitor, in SCCHN models with the aim of identifying predictive biomarkers of response. HPV-negative or HPV-positive SCCHN cell lines (n = 8) and patient-derived tumor xenograft (PDTX) models (n = 6) were used. The models were classified according to their sensitivity to ribociclib to investigate potential predictive biomarkers. Ribociclib had a cytostatic effect in some HPV-negative SCCHN models but had no effect in HPV-positive models. In SCCHN cell lines and PDTXs, the retinoblastoma (Rb) protein expression level correlated with ribociclib activity. Rb knockdown was, however, not sufficient to block G₀-G₁ arrest induced by ribociclib in Detroit-562 where p107, p130, and Forkhead BOX M1 (FOXM1) were also implicated in ribociclib activity. Cell lines harboring epithelial-to-mesenchymal transition (EMT) features were less sensitive to ribociclib than those with an epithelial phenotype. Rb downregulation induced EMT in our Rb-expressing SCCHN cell lines. However, ribociclib still had significant activity in one PDTX model with high Rb and vimentin expression, suggesting that the presence of vimentin alone is not enough to induce ribociclib resistance. These findings suggest that CDK4/6 inhibitors should be investigated in patients with HPV-negative SCCHN with high Rb expression and an epithelial phenotype. Although these biomarkers are not predictive in all cases, they may enrich the population that could benefit from CDK4/6 inhibitors.