Biological activities and molecular targets of the human papillomavirus E7 oncoprotein

Clinical outcomes and prognostic factors of concurrent chemoradiotherapy for anal squamous cell carcinoma in Japan

BACKGROUND

Concurrent chemoradiotherapy (CCRT) is the standard treatment for locoregional anal squamous cell carcinoma (ASCC) in western countries. However, there have been few reports on the clinical outcomes of CCRT in Japan. This study aimed to evaluate the clinical outcomes of CCRT, prognostic factors, and the clinical impact of programmed cell death-ligand 1 (PD-L1) expression of ASCC in Japan.

METHODS

Patients with locoregional ASCC were enrolled between 2007 and 2017. All patients received CCRT consisting of ≥ 45 Gy of radiation, 5-fluorouracil, and mitomycin C. Disease-free survival (DFS), overall survival (OS), and adverse events (AEs) were estimated. Expression of p16 and PD-L1 were assessed by immunohistochemical staining (IHC).

RESULTS

This study included 36 patients, of whom 30 (83.3%) were female. Among the participants, 32 (88.9%) achieved complete clinical remission, while six (16.7%) experienced recurrence. The five-year DFS and five-year OS were 72.2% and 84.7%, respectively. Grades ≥ 3 serious AEs included neutropenia in 10 (27.7%) and perianal dermatitis in eight (22.2%). In a univariate analysis, male sex, lymph node metastasis, and large tumor size were significantly associated with worse outcome. In a multivariate analysis, tumor size was an independent factor associated with short DFS. Of the 30 patients whose biopsy specimens were available for IHC, 29 (96.7%) were positive for p16, and 13 (43.3%) were positive for PD-L1. However, PD-L1 expression did not show any clinical impact.

CONCLUSIONS

The comparative etiology, clinical outcomes, and prognostic factors of CCRT observed in Japanese patients with locoregional ASCC were consistent with western data.

Transcriptionally Active Human Papillomavirus Infection in a Minority of Esophageal Squamous Cell Carcinomas in North America

The role of Human papillomavirus (HPV) infection in esophageal squamous cell carcinoma (ESCC) is a topic of ongoing debate. This study used two screening approaches to look for evidence of HPV infection in esophageal squamous cell carcinoma. We initially checked for HPV infection in a randomly selected group of 53 ESCC cases. We did not detect any tumors positive for high-risk HPV. However, during clinical practice, we identified an HPV-positive ESCC in the distal esophagus, which tested positive for HPV16. This index case was TP53 wild-type, as determined by next-generation DNA sequencing (NGS). Since TP53 mutations are rare in other HPV-driven cancers, we improved our screening method by limiting our screen to a subset of ESCC cases without TP53 mutations. A second screen of 95 ESCCs (from 93 patients) sequenced by NGS revealed an additional 7 ESCCs with TP53 wild-type status (7.3% of the total). Of the 7 cases, 2 cases were found to be high-risk HPV positive. Both patients also tested positive for circulating cell-free HPV DNA and had a complete response to neoadjuvant chemoradiation. The index patient had microscopic residual tumor following neoadjuvant therapy. The patient underwent adjuvant immunotherapy and remained disease free after 22 months of surveillance. This study affirms the transcriptionally active status of high-risk HPV in a minority of ESCC patients in North America.

Noncanonical functions of telomerase and telomeres in viruses-associated cancer

The cause of cancer is attributed to the uncontrolled growth and proliferation of cells resulting from genetic changes and alterations in cell behavior, a phenomenon known as epigenetics. Telomeres, protective caps on the ends of chromosomes, regulate both cellular aging and cancer formation. In most cancers, telomerase is upregulated, with the telomerase reverse transcriptase (TERT) enzyme and telomerase RNA component (TERC) RNA element contributing to the maintenance of telomere length. Additionally, it is noteworthy that two viruses, human papillomavirus (HPV) and Epstein-Barr virus (EBV), utilize telomerase for their replication or persistence in infected cells. Also, TERT and TERC may play major roles in cancer not related to telomere biology. They are involved in the regulation of gene expression, signal transduction pathways, cellular metabolism, or even immune response modulation. Furthermore, the crosstalk between TERT, TERC, RNA-binding proteins, and microRNAs contributes to a greater extent to cancer biology. To understand the multifaceted roles played by TERT and TERC in cancer and viral life cycles, and then to develop effective therapeutic strategies against these diseases, are fundamental for this goal. By investigating deeply, the complicated mechanisms and relationships between TERT and TERC, scientists will open the doors to new therapies. In its analysis, the review emphasizes the significance of gaining insight into the multifaceted roles that TERT and TERC play in cancer pathogenesis, as well as their involvement in the viral life cycle for designing effective anticancer therapy approaches.

IRF3 activates RB to authorize cGAS-STING-induced senescence and mitigate liver fibrosis

Cytosolic double-stranded DNA surveillance by cyclic GMP-AMP synthase (cGAS)-Stimulator of Interferon Genes (STING) signaling triggers cellular senescence, autophagy, biased mRNA translation, and interferon-mediated immune responses. However, detailed mechanisms and physiological relevance of STING-induced senescence are not fully understood. Here, we unexpectedly found that interferon regulatory factor 3 (IRF3), activated during innate DNA sensing, forms substantial endogenous complexes in the nucleus with retinoblastoma (RB), a key cell cycle regulator. The IRF3-RB interaction attenuates cyclin-dependent kinase 4/6 (CDK4/6)-mediated RB hyperphosphorylation that mobilizes RB to deactivate E2 family (E2F) transcription factors, thereby driving cells into senescence. STING-IRF3-RB signaling plays a notable role in hepatic stellate cells (HSCs) within various murine models, pushing activated HSCs toward senescence. Accordingly, IRF3 global knockout or conditional deletion in HSCs aggravated liver fibrosis, a process mitigated by the CDK4/6 inhibitor. These findings underscore a straightforward yet vital mechanism of cGAS-STING signaling in inducing cellular senescence and unveil its unexpected biology in limiting liver fibrosis.

Downregulation of LAMB3 Altered the Carcinogenic Properties of Human Papillomavirus 16-Positive Cervical Cancer Cells

Nearly all cervical cancer cases are caused by infection with high-risk human papillomavirus (HR-HPV) types. The mechanism of cervical cell transformation is related to the powerful action of viral oncoproteins and cellular gene alterations. Transcriptomic data from cervical cancer and normal cervical cells were utilized to identify upregulated genes and their associated pathways. The laminin subunit beta-3 (LAMB3) mRNAwas overexpressed in cervical cancer and was chosen for functional analysis. The LAMB3 was predominantly expressed in the extracellular region and the plasma membrane, which play a role in protein binding and cell adhesion molecule binding, leading to cell migration and tissue development. LAMB3 was found to be implicated in the pathway in cancer and the PI3K-AKT signaling pathway. LAMB3 knockdown decreased cell migration, invasion, anchorage-dependent and anchorage-independent cell growth and increased the number of apoptotic cells. These effects were linked to a decrease in protein levels involved in the PI3K-AKT signaling pathway and an increase in p53 protein. This study demonstrated that LAMB3 could promote cervical cancer cell migration, invasion and survival.

Computational and AI-driven 3D structural analysis of human papillomavirus (HPV) oncoproteins E5, E6, and E7 reveal significant divergence of HPV E5 between low-risk and high-risk genotypes

There are over 220 identified genotypes of Human papillomavirus (HPV), and the HPV genome encodes 3 major oncogenes, E5, E6, and E7. Conservation and divergence in protein sequence and function between low-risk versus high-risk oncogenic HPV genotypes has not been fully characterized. Here, we used modern computational and structural folding algorithms to perform a comparative analysis of HPV E5, E6, and E7 between multiple low risk and high risk genotypes. We first identified significantly greater sequence divergence in E5 between low- and high-risk genotypes compared to E6 and E7. Next, we used AlphaFold to model the structure of papillomavirus proteins and complexes with high confidence, including some with no established consensus structure. We observed that HPV E5, but not E6 or E7, had a dramatically different 3D structure between low-risk and high-risk genotypes. To our knowledge, this is the first comparative analysis of HPV proteins using Alphafold artificial intelligence (AI) system. The marked differences in E5 sequence and structure in high-risk HPVs may contribute in important and underappreciated ways to the development of HPV-associated cancers.

Activating STING/TBK1 suppresses tumor growth via degrading HPV16/18 E7 oncoproteins in cervical cancer

Cervical cancer is the most common gynecologic cancer, etiologically related to persistent infection of human papillomavirus (HPV). Both the host innate immunity system and the invading HPV have developed sophisticated and effective mechanisms to counteract each other. As a central innate immune sensing signaling adaptor, stimulator of interferon genes (STING) plays a pivotal role in antiviral and antitumor immunity, while viral oncoproteins E7, especially from HPV16/18, are responsible for cell proliferation in cervical cancer, and can inhibit the activity of STING as reported. In this report, we find that activation of STING-TBK1 (TANK-binding kinase 1) promotes the ubiquitin-proteasome degradation of E7 oncoproteins to suppress cervical cancer growth. Mechanistically, TBK1 is able to phosphorylate HPV16/18 E7 oncoproteins at Ser71/Ser78, promoting the ubiquitination and degradation of E7 oncoproteins by E3 ligase HUWE1. Functionally, activated STING inhibits cervical cancer cell proliferation via down-regulating E7 oncoproteins in a TBK1-dependent manner and potentially synergizes with radiation to achieve better effects for antitumor. Furthermore, either genetically or pharmacologically activation of STING-TBK1 suppresses cervical cancer growth in mice, which is independent on its innate immune defense. In conclusion, our findings represent a new layer of the host innate immune defense against oncovirus and provide that activating STING/TBK1 could be a promising strategy to treat patients with HPV-positive cervical cancer.

Epidemiology, Molecular Pathogenesis, Immuno-Pathogenesis, Immune Escape Mechanisms and Vaccine Evaluation for HPV-Associated Carcinogenesis

Human papillomavirus (HPV) is implicated in over 90% of cervical cancer cases, with factors like regional variability, HPV genotype, the population studied, HPV vaccination status, and anatomical sample collection location influencing the prevalence and pathology of HPV-induced cancer. HPV-16 and -18 are mainly responsible for the progression of several cancers, including cervix, anus, vagina, penis, vulva, and oropharynx. The oncogenic ability of HPV is not only sufficient for the progression of malignancy, but also for other tumor-generating steps required for the production of invasive cancer, such as coinfection with other viruses, lifestyle factors such as high parity, smoking, tobacco chewing, use of contraceptives for a long time, and immune responses such as stimulation of chronic stromal inflammation and immune deviation in the tumor microenvironment. Viral evasion from immunosurveillance also supports viral persistence, and virus-like particle-based prophylactic vaccines have been licensed, which are effective against high-risk HPV types. In addition, vaccination awareness programs and preventive strategies could help reduce the rate and incidence of HPV infection. In this review, we emphasize HPV infection and its role in cancer progression, molecular and immunopathogenesis, host immune response, immune evasion by HPV, vaccination, and preventive schemes battling HPV infection and HPV-related cancers.

Recent advancement of nanomedicine-based targeted delivery for cervical cancer treatment

Cervical cancer is a huge worldwide health burden, impacting women in impoverished nations in particular. Traditional therapeutic approaches, such as surgery, radiation therapy, and chemotherapy, frequently result in systemic toxicity and ineffectiveness. Nanomedicine has emerged as a viable strategy for targeted delivery of therapeutic drugs to cancer cells while decreasing off-target effects and increasing treatment success in recent years. Nanomedicine for cervical cancer introduces several novel aspects that distinguish it from previous treatment options such as tailored delivery system, precision targeting, combination therapies, real-time monitoring and diverse nanocarriers to overcome the limitations of one another. This abstract presents recent advances in nanomedicine-based tailored delivery systems for the treatment of cervical cancer. Liposomes, polymeric nanoparticles, dendrimers, and carbon nanotubes have all been intensively studied for their ability to transport chemotherapeutic medicines, nucleic acids, and imaging agents to cervical cancer cells. Because of the way these nanocarriers are designed, they may cross biological barriers and preferentially aggregate at the tumor site, boosting medicine concentration and lowering negative effects on healthy tissues. Surface modification of nanocarriers with targeting ligands like antibodies, peptides, or aptamers improves specificity for cancer cells by identifying overexpressed receptors or antigens on the tumor surface. Furthermore, nanomedicine-based techniques have made it possible to co-deliver numerous therapeutic drugs, allowing for synergistic effects and overcoming drug resistance. In preclinical and clinical investigations, combination treatments comprising chemotherapeutic medicines, gene therapy, immunotherapy, and photodynamic therapy have showed encouraging results, opening up new avenues for individualized and multimodal treatment regimens. Furthermore, the inclusion of contrast agents and imaging probes into nanocarrier systems has enabled real-time monitoring and imaging of treatment response. This enables the assessment of therapy efficacy, the early diagnosis of recurrence, and the optimization of treatment regimens.

HPV Testing and its Role in Cervical Cancer Screening

The recognition that persistent infection with carcinogenic human papillomavirus (HPV) is a necessary cause of cervical precancer and cancer has led to the introduction of HPV testing into cervical cancer screening, either as a primary screening test or in conjunction with cervical cytology (i.e., co-testing). HPV testing has much higher sensitivity for detection of cervical precancer and provides greater long-term reassurance if negative compared to cytology. However, most HPV infections are transient, and do not progress to invasive cancer, thus triage tests are required to identify individuals who should be referred to colposcopy for diagnostic evaluation. This chapter begins with a description of the biology, natural history, and epidemiology of HPV as a foundation for understanding the role of HPV in cervical carcinogenesis. This section is followed by a detailed discussion regarding the introduction of HPV-based testing and triage into cervical cancer screening and management. Summarized triage tests include cervical cytology, HPV genotyping, p16/Ki-67 dual stain, and HPV and cellular methylation markers. The final section of this chapter includes an important discussion on cervical cancer disparities, particularly within the United States, followed by concluding remarks.

Concatenation of molecular docking and dynamics simulation of human papillomavirus type 16 E7 oncoprotein targeted ligands: In quest of cervical cancer's treatment

The Human papillomaviruses type 16 E7 oncoprotein is a 98-amino-acid, 11-kilodalton acidic oncoprotein with three conserved portions. Due to its interaction with the pRb-E2F complex, CKII, CKI (mostly p21), and even HDAC1, it possesses strong transformative and carcinogenic qualities that inhibit normal differentiation and cell cycle regulation. Here, we target the E7 oncoprotein using two prior research active compounds: asarinin and thiazolo[3,2-a]benzimidazole-3(2H)-one,2-(2-fluorobenzylideno)-7,8-dimethyl (thiazolo), and valproic acid as a control. We are performing molecular docking followed by molecular dynamic analysis. By acting as competitive inhibitors in the binding site, it was hypothesized that both drugs would inhibit E7-mediated pRb degradation and E7-mediated p21 degradation, resulting in decreased cell cycle progression, immortalization, and proliferation. In addition, we expect that the direct inhibitory action of valproic acid in E7 will target the CKII-mediated phosphorylation pathway necessary for destabilizing p130 and pRb. According to the results of the dynamic simulation, stable interactions exist between every compound. Despite the instability of E7 protein, stability results indicate that both natural chemicals are preferable, with thiazolo outperforming valproic acid.

Performance of p16/Ki67 Immunostaining for Triage of Elderly Women with Atypical Squamous Cells of Undetermined Significance

BACKGROUND

The p16/Ki67 technique has been poorly studied in postmenopausal women with ASC-US cytology. The objective of this study was to compare the accuracy of p16/Ki67 staining, HPV testing and HPV 16 genotyping for the identification of CIN2 + lesions in postmenopausal women with ASC-US cytology.

METHOD

A total of 324 postmenopausal women with positive ASC-US were included. The women underwent HPV test, colposcopy, and biopsy. The slides were discolored and then stained with the CINtec Plus Kit for p16/Ki67. The HPV test results were classified as HPV16 +, hrHPV+ (other hrHPV genotypes), or HPV negative.

RESULTS

The p16/Ki67 sensitivity for CIN2+ was 94.5%, the specificity 86.6%, PPV of 59% and NPV of 95.9%. The HPV test showed a sensitivity of 96.4% for CIN2+, a specificity of 62.8%, a PPV of 35% and a NPV of 98.8%. In postmenopausal women, the prevalence of genotype 16 decreases in favor of the other high-risk genotypes.

CONCLUSION

Given the low sensitivity of cytology and the low percentage of HPV16-positive cancers among elderly women, triage via cytology and genotyping is not the best strategy; double staining cytology shows high profiles of sensibility and specificity for CIN2+ in ASCUS postmenopausal women.

Irradiation is not sufficient to eradicate residual immortalized erythroid cells in in vitro-generated red blood cell products

BACKGROUND

The generation of immortalized erythroid progenitor cell lines capable of producing enough red blood cells (RBCs) for blood transfusion typically requires the overexpression of oncogenes in stem cells or progenitor cells to permanently proliferate immature cells. It is essential that any live oncogene-expressing cells are eliminated from the final RBC products for clinical use.

STUDY DESIGN AND METHODS

It is believed that safety issues may be resolved by using a leukoreduction filter or by irradiating the final products, as is conventionally done in blood banks; however, this has never been proven to be effective. Therefore, to investigate whether immortalized erythroblasts can be completely removed using γ-ray irradiation, we irradiated the erythroblast cell line, HiDEP, and the erythroleukemic cell line, K562 that overexpress HPV16 E6/E7. We then analyzed the extent of cell death using flow cytometry and polymerase chain reaction (PCR). The cells were also subjected to leukoreduction filters.

RESULTS

Using γ-ray irradiation at 25 Gy, 90.4% of HiDEP cells, 91.6% of K562-HPV16 E6/E7 cells, and 93.5% of non-transduced K562 cells were dead. In addition, 5.58 × 10⁷ HiDEP cells were passed through a leukoreduction filter, and 38 intact cells were harvested, revealing a filter removal efficiency of 99.9999%. However, both intact cells and oncogene DNA were still detected.

DISCUSSION

Irradiation cannot induce total cell death of oncogene-expressing erythroblasts and leukocyte filter efficiency is not 100%. Therefore, our findings imply that for clinical applications, safer methods should be developed to completely remove residual nucleated cells from cell line-derived RBC products.

Utilization of a cell-penetrating peptide-adaptor for delivery of human papillomavirus protein E2 into cervical cancer cells to arrest cell growth and promote cell death

BACKGROUND

Human papillomavirus (HPV) is the causative agent of nearly all forms of cervical cancer, which can arise upon viral integration into the host genome and concurrent loss of viral regulatory gene E2. Gene-based delivery approaches show that E2 reintroduction reduces proliferative capacity and promotes apoptosis in vitro.

AIMS

This work explored if our calcium-dependent protein-based delivery system, TAT-CaM, could deliver functional E2 protein directly into cervical cancer cells to limit proliferative capacity and induce cell death.

MATERIALS AND RESULTS

TAT-CaM and the HPV16 E2 protein containing a CaM-binding sequence (CBS-E2) were expressed and purified from Escherichia coli. Calcium-dependent binding kinetics were verified by biolayer interferometry. Equimolar TAT-CaM:CBS-E2 constructs were delivered into the HPV16+ SiHa cell line and uptake verified by confocal microscopy. Proliferative capacity was measured by MTS assay and cell death was measured by release of lactate dehydrogenase. As a control, human microvascular cells (HMECs) were used. As expected, TAT-CaM bound CBS-E2 with high affinity in the presence of calcium and rapidly disassociated upon its removal. After introduction by TAT-CaM, fluorescently labeled CBS-E2 was detected in cellular interiors by orthogonal projections taken at the depth of the nucleus. In dividing cells, E2 relocalized to regions associated with the mitotic spindle. Cells receiving a daily dose of CBS-E2 for 4 days showed a significant reduction in metabolic activity at low doses and increased cell death at high doses compared to controls. This phenotype was retained for 7 days with no further treatments. When subcultured on day 12, treated cells regained their proliferative capacity.

CONCLUSIONS

Using the TAT-CaM platform, bioactive E2 protein was delivered into living cervical cancer cells, inducing senescence and cell death in a time- and dose-dependent manner. These results suggest that this nucleic acid and virus-free delivery method could be harnessed to develop novel, effective protein therapeutics.

CDK4/6 Inhibition Induces Senescence and Enhances Radiation Response by Disabling DNA Damage Repair in Oral Cavity Squamous Cell Carcinoma

PURPOSE

HPV(-) OCSCC resists radiation treatment. The CDKN2A gene, encoding p16INK4A, is commonly disrupted in OCSCC. p16 inhibits CDK4/CDK6, leading to cell cycle arrest, but the biological sequelae of CDK4/6 inhibition in OCSCC remains understudied. This study examines whether inhibition of CDK4/6 enhances radiation response in OCSCC.

METHODS

MTT assays were performed in OCSCC cell lines HN5 and CAL27 following treatment with palbociclib. Clonogenic survival and synergy were analyzed after radiation (RT-2 or 4Gy), palbociclib (P) (0.5 µM or 1 µM), or concurrent combination treatment (P+RT). DNA damage/repair and senescence were examined. CDK4/6 were targeted via siRNA to corroborate P+RT effects. Three-dimensional immortalized spheroids and organoids derived from patient tumors (conditionally reprogrammed OCSCC CR-06 and CR-18) were established to further examine and validate responses to P+RT.

RESULTS

P+RT demonstrated reduced viability and synergy, increased β-gal expression (~95%), and ~two-fold higher γH2AX. Rad51 and Ku80 were reduced after P+RT, indicating impairment of both HR and NHEJ. siCDK4/6 increased senescence with radiation. Spheroids showed reduced proliferation and size with P+RT. CR-06 and CR-18 further demonstrated three-fold reduced proliferation and organoids size with P+RT.

CONCLUSION

Targeting CDK4/6 can lead to improved efficacy when combined with radiation in OCSCC by inducing senescence and inhibiting DNA damage repair.

Novel canonical and non-canonical viral antigens extend current targets for immunotherapy of HPV-driven cervical cancer

Current immunotherapeutic approaches for human papillomavirus (HPV)-driven cervical cancer target the viral oncogenes E6 and E7. We report viral canonical and alternative reading frame (ARF)-derived sequences presented on cervical tumor cells, including antigens encoded by the conserved viral gene E1. We confirm immunogenicity of the identified viral peptides in HPV-positive women, and women with cervical intraepithelial neoplasia. We observe consistent transcription of the E1, E6, and E7 genes in 10 primary cervical tumor resections from the four most common high-risk HPV subtypes (HPV16, 18, 31, and 45), suggesting the suitability of E1 as therapeutic target. We finally confirm HLA presentation of canonical peptides derived from E6 and E7, and ARF-derived viral peptides from a reverse-strand transcript spanning the HPV E1 and E2 genes in primary human cervical tumor tissue. Our results extend currently known viral immunotherapeutic targets in cervical cancer and highlight E1 as an important cervical cancer antigen.

Human Papilloma Virus-Infected Cells

Human papillomavirus (HPV) is associated with infection of different tissues, such as the cervix, anus, vagina, penis, vulva, oropharynx, throat, tonsils, back of the tongue, skin, the lungs, among other tissues. HPV infection may or may not be associated with the development of cancer, where HPVs not related to cancer are defined as low-risk HPVs and are associated with papillomatosis disease. In contrast, high-risk HPVs (HR-HPVs) are associated with developing cancers in areas that HR-HPV infects, such as the cervix. In general, infection of HPV target cells is regulated by specific molecules and receptors that induce various conformational changes of HPV capsid proteins, allowing activation of HPV endocytosis mechanisms and the arrival of the HPV genome to the human cell nucleus. After the transcription of the HPV genome, the HPV genome duplicates exponentially to lodge in a new HPV capsid, inducing the process of exocytosis of HPV virions and thus releasing a new HPV viral particle with a high potential of infection. This infection process allows the HPV viral life cycle to conclude and enables the growth of HPV virions. Understanding the entire infection process has been a topic that researchers have studied and developed for decades; however, there are many things to still understand about HPV infection. A thorough understanding of these HPV infection processes will allow new potential treatments for HPV-associated cancer and papillomatosis. This chapter focuses on HPV infection, the process that will enable HPV to complete its HPV life cycle, emphasizing the critical role of different molecules in allowing this infection and its completion during the HPV viral life cycle.

Investigation of Curcumin-Loaded OA400 Nanoparticle's Effect on the Expression of E6 and E7 Human Papilloma-Virus Oncogenes and P53 and Rb Factors in HeLa Cell Line

Background

Curcumin, a compound derived from the root of the Curcuma longa, has been confirmed as an anticancer, chemoprotective, and gene/protein regulatory agent. Nanoformulation of curcumin has been developed to increase its targeting efficiency, solubility, controlled release, and physical and chemical stability.

Objectives

This study investigated the effect of new nano-type curcumin, oleic acid-derived dendrosome (OA400 nanoparticles), on the expression of E6 and E7 human papillomavirus oncogenes and P53 and Rb factors in the HeLa cell line. After preparing nano-curcumin by mixing OA400 nano-carrier and curcumin, its effect was considered on the human cervical cancer cell line (HeLa cell line RRID: CVCL_003) and normal fibroblast cells.

Methods

MTT assay and flow cytometry were used to evaluate cell viability and apoptosis. Furthermore, real-time RT-PCR and western blot analyses assessed RNA and protein expression of E6, E7, P53, and Rb. Statistical analyses were performed by GraphPad Prism 7 software.

Results

The nanoformulation of curcumin could reduce the expression of E6 and E7 oncogenes and increase P53 and Rb tumor suppressors in HeLa cancerous cells at 15 μM concentration; however, it had no significant effect on the viability of normal fibroblast cells. On the other hand, curcumin altered the expression of these genes at a 50-μM concentration. Gene and protein expression analysis indicated the up-regulation of P53 and Rb factors and the down-regulation of E6 and E7 under the influence of nano-curcumin treatment more than curcumin.

Conclusions

These data indicate the potential of curcumin-loaded OA400 nanoparticles to be considered as a treatment option in cervical cancer investigations.

Pathological Similarities in the Development of Papillomavirus-Associated Cancer in Humans, Dogs, and Cats

Simple Summary

Papillomavirus (PV) infection affects many species, including humans and domestic animals, such as dogs and cats. Some of these infections involve the development of cancer due to the presence of PV. There are similarities in the pathology of these three PV-associated cancers, which may provide crucial insights into cancer development in these species, extrapolating both markers and possible treatment in the three species. For example, the oncoproteins E5, E6, and E7 are the main causes of the development of cancer associated with PV, and the possible therapies associated with the blockage or reduction of these oncoproteins can be of great benefit for the reduction and/or elimination of cancer associated with PV. Thus, our review focuses on the similarities in the context of pathology and biomarkers in canine, feline, and human cancers associated with PV. We review the main biomarkers, E5, E6, and E7 oncoproteins, and their overexpression in Canis familiaris, Felis catus, and human papillomavirus and their association with the development of cancer. Furthermore, we also discuss that a potential treatment for PV-related cancer is the reduction or blocking of these oncoproteins.

Abstract

Canis familiaris, Felis catus, and human papillomavirus are nonenveloped viruses that share similarities in the initiation and development of cancer. For instance, the three species overexpress the oncoproteins E6 and E7, and Canis familiaris and human papillomavirus overexpress the E5 oncoprotein. These similarities in the pathophysiology of cancer among the three species are beneficial for treating cancer in dogs, cats, and humans. To our knowledge, this topic has not been reviewed so far. This review focuses on the information on cancer research in cats and dogs comparable to that being conducted in humans in the context of comparative pathology and biomarkers in canine, feline, and human cancer. We also focus on the possible benefit of treatment associated with the E5, E6, and E7 oncoproteins for cancer in dogs, cats, and humans.

HPV18 oncoproteins driven expression of PKM2 reprograms HeLa cell metabolism to maintain aerobic glycolysis and viability

The molecular basis of human papillomavirus (HPV)-mediated cellular immortalization and malignant transformation has illustrated an indispensable role of viral E6/E7-oncoproteins. However, the impact of viral-oncoproteins on the metabolic phenotype of cancer cells remains ambiguous. We showed silencing of HPV18-encoded E6/E7-oncoprotein significantly reduced glucose consumption, lactate production, ATP level and viability. Silencing of HPV18-encoded E6/E7 in HeLa cells significantly down-regulated expression and activity of HK1, HK2, LDHA, and LDHB. Interestingly, there was an increased pyruvate kinase activity due to switch in expression from PKM2 isoform to PKM1. The switch in favor of alternatively spliced isoform PKM1, was regulated by viral-E6/E7-oncoprotein by inhibiting the c-Myc/hnRNP-axis. Further, the near absence of the PKM1 protein despite an adequate amount of PKM1 mRNA in HeLa cells was due to its proteasomal degradation. Our results suggests HPV18-encoded E6/E7 driven preferential expression of PKM2 is essential to support aerobic glycolysis and cell proliferation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-022-00776-w.

The HPV Induced Cancer Resource (THInCR): a Suite of Tools for Investigating HPV-Dependent Human Carcinogenesis

Human papillomaviruses (HPVs) are highly infectious and cause the most common sexually transmitted viral infections. They induce hyperproliferation of squamous epithelial tissue, often forming warts. Virally encoded proteins reprogram gene expression and cell growth to create an optimal environment for viral replication. In addition to their normal roles in infection, functional alterations induced by viral proteins establish conditions that frequently contribute to human carcinogenesis. In fact, ~5% of human cancers are caused by HPVs, with virtually all cervical squamous cell carcinomas (CESC) and an increasing number of head and neck squamous cell carcinomas (HNSC) attributed to HPV infection. The Cancer Genome Atlas (TCGA) molecularly characterized thousands of primary human cancer samples in many cancer types, including CESC and HNSC, and created a comprehensive atlas of genomic, epigenomic, and transcriptomic data. This publicly available genome-wide information provides an unprecedented opportunity to expand the knowledge of the role that HPV plays in human carcinogenesis. While many tools exist to mine these data, few, if any, focus on the comparison of HPV-positive cancers with their HPV-negative counterparts or adjacent normal control tissue. We have constructed a suite of web-based tools, The HPV Induced Cancer Resource (THInCR), to utilize TCGA data for research related to HPV-induced CESC and HNSC. These tools allow investigators to gain greater biological and medical insights by exploring the impacts of HPV on cellular gene expression (mRNA and microRNA), altered gene methylation, and associations with patient survival and immune landscape features. These tools are accessible at https://thincr.ca/. IMPORTANCE The suite of analytical tools of THInCR provides the opportunity to investigate the roles that candidate target genes identified in cell lines or other model systems contribute to in actual HPV-dependent human cancers and is based on large-scale TCGA data sets. Expression of target genes, including both mRNA and microRNA, can be correlated with HPV gene expression, epigenetic changes in DNA methylation, patient survival, and numerous immune features, like leukocyte infiltration, interferon gamma response, T cell response, etc. Data from these analyses may immediately provide evidence to validate in vitro observations, reveal insights into mechanisms of virus-mediated alterations in cell growth, behavior, gene expression, and innate and adaptive immunity and may help hypothesis generation for further investigations.

AIB1 is a novel target of the high-risk HPV E6 protein and a biomarker of cervical cancer progression

The high-risk human papillomaviruses (HPV-16, -18) are critical etiologic agents in human malignancy, most importantly in cervical cancer. These oncogenic viruses encode the E6 and E7 proteins that are uniformly retained and expressed in cervical cancers and required for maintenance of the tumorigenic phenotype. The E6 and E7 proteins were first identified as targeting the p53 and pRB tumor suppressor pathways, respectively, in host cells, thereby leading to disruption of cell cycle controls. In addition to p53 degradation, a number of other functions and critical targets for E6 have been described, including telomerase, Myc, PDZ-containing proteins, Akt, Wnt, mTORC1, as well as others. In this study, we identified Amplified in Breast Cancer 1 (AIB1) as a new E6 target. We first found that E6 and hTERT altered similar profiling of gene expression in human foreskin keratinocytes (HFK), independent of telomerase activity. Importantly, AIB1 was a common transcriptional target of both E6 and hTERT. We then verified that high-risk E6 but not low-risk E6 expression led to increases in AIB1 transcript levels by real-time RT-PCR, suggesting that AIB1 upregulation may play an important role in cancer development. Western blots demonstrated that AIB1 expression increased in HPV-16 E6 and E7 expressing (E6E7) immortalized foreskin and cervical keratinocytes, and in three of four common cervical cancer cell lines as well. Then, we evaluated the expression of AIB1 in human cervical lesions and invasive carcinoma using immunohistochemical staining. Strikingly, AIB1 showed positivity in the nucleus of cells in the immediate suprabasal epithelium, while nuclei of the basal epithelium were negative, as evident in the Cervical Intraepithelial Neoplasia 1 (CIN1) samples. As the pathological grading of cervical lesions increased from CIN1, CIN2, CIN3 carcinoma in situ and invasive carcinoma, AIB1 staining increased progressively, suggesting that AIB1 may serve as a novel histological biomarker for cervical cancer development. For cases of invasive cervical carcinoma, AIB1 staining was specific to cancerous lesions. Increased expression of AIB1 was also observed in transgenic mouse cervical neoplasia and cancer models induced by E6E7 and estrogen. Knockdown of AIB1 expression in E6E7 immortalized human cervical cells significantly abolished cell proliferation. Taken together, these data support AIB1 as a novel target of HPV E6 and a biomarker of cervical cancer progression.

miR-34a negatively regulates cell cycle factor Cdt2/DTL in HPV infected cervical cancer cells

MicroRNAs have emerged as an important regulator of cell cycle and various other cellular processes. Aberration in microRNAs has been linked with development of several cancers and other diseases but still very little is known about the mechanism by which they regulate these cellular events. High risk human papilloma virus (HR HPV) is the causative agent of 99% of cervical cancer cases which attenuates multiple tumor suppressors and checkpoint factors of the host cell. The viral proteins also stabilize many oncogenic factors, including an essential cell cycle regulator Cdt2/DTL which in turn promotes cell transformation and proliferation. In this study, we report that a micro-RNA, miR-34a by suppressing HPV E6 protein, destabilizes Cdt2/DTL protein level in HPV infected cervical cancer cell lines. Destabilization of Cdt2 stabilizes pro-apoptotic and onco-suppressor proteins like p21 and Set8 and suppresses cell proliferation, invasion and migration capabilities of the HPV positive cervical cancer cells. Overexpression of either HPV E6 or Cdt2 genes along with miR-34a restored back the suppressed proliferation rate. This study is the first-ever report to show that miR-34a regulates cell cycle factor Cdt2 by suppressing viral E6 protein level, thus opening up the possibility of exploring miR-34a as a specific therapy for cervical cancer treatment.

High-Risk Human Papillomavirus Oncogenic E6/E7 mRNAs Splicing Regulation

High-risk human papillomavirus infection may develop into a persistent infection that is highly related to the progression of various cancers, including cervical cancer and head and neck squamous cell carcinomas. The most common high-risk subtypes are HPV16 and HPV18. The oncogenic viral proteins expressed by high-risk HPVs E6/E7 are tightly involved in cell proliferation, differentiation, and cancerous transformation since E6/E7 mRNAs are derived from the same pre-mRNA. Hence, the alternative splicing in the E6/E7-coding region affects the balance of the E6/E7 expression level. Interrupting the balance of E6 and E7 levels results in cell apoptosis. Therefore, it is crucial to understand the regulation of E6/E7 splice site selection and the interaction of splicing enhancers and silencers with cellular splicing factors. In this review, we concluded the relationship of different E6/E7 transcripts with cancer progression, the known splicing sites, and the identified cis-regulatory elements within high-risk HPV E6/E7-coding region. Finally, we also reviewed the role of various splicing factors in the regulation of high-risk HPV oncogenic E6/E7 mRNA splicing.

Cell cycle regulation: p53-p21-RB signaling

The retinoblastoma protein RB and the transcription factor p53 are central tumor suppressors. They are often found inactivated in various tumor types. Both proteins play central roles in regulating the cell division cycle. RB forms complexes with the E2F family of transcription factors and downregulates numerous genes. Among the RB-E2F target genes, a large number code for key cell cycle regulators. Their transcriptional repression by the RB-E2F complex is released through phosphorylation of RB, leading to expression of the cell cycle regulators. The release from repression can be prevented by the cyclin-dependent kinase inhibitor p21/CDKN1A. The CDKN1A gene is transcriptionally activated by p53. Taken together, these elements constitute the p53-p21-RB signaling pathway. Following activation of p53, for example by viral infection or induction of DNA damage, p21 expression is upregulated. High levels of p21 then result in RB-E2F complex formation and downregulation of a large number of cell cycle genes. Thus, p53-dependent transcriptional repression is indirect. The reduced expression of the many regulators leads to cell cycle arrest. Examination of the p53-p21-RB targets and genes controlled by the related p53-p21-DREAM signaling pathway reveals that there is a large overlap of the two groups. Mechanistically this can be explained by replacing RB-E2F complexes with the DREAM transcriptional repressor complex at E2F sites in target promoters. In contrast to RB-E2F, DREAM can downregulate genes also through CHR transcription factor binding sites. This results in a distinct gene set controlled by p53-p21-DREAM signaling independent of RB-E2F. Furthermore, RB has non-canonical functions without binding to E2F and DNA. Such a role of RB supporting DREAM formation may be exerted by the RB-SKP2-p27-cyclin A/E-CDK2-p130-DREAM link. In the current synopsis, the mechanism of regulation by p53-p21-RB signaling is assessed and the overlap with p53-p21-DREAM signaling is examined.

Loss of the E6AP ubiquitin ligase induces p53-dependent phosphorylation of HPV-18 E6 in cells derived from cervical cancer

Cancer-causing HPV E6 oncoproteins contain a well-characterised phospho-acceptor site within the PDZ (PSD-95/Dlg/ZO-1) binding motif (PBM) at the C-terminus of the protein. Previous studies have shown that the threonine or serine residue in the E6 PBM is subject to phosphorylation by several stress-responsive cellular kinases, upon the induction of DNA damage in cervical cancer-derived cells. However, there is little information about the regulation of E6 phosphorylation in the absence of DNA damage and whether there may be other pathways by which E6 is phosphorylated. In this study, we demonstrate that loss of E6AP results in a dramatic increase in the levels of phosphorylated E6 (pE6), despite the expected overall reduction in total E6 protein levels. Furthermore, phosphorylation of E6 requires transcriptionally active p53 and occurs in a manner which is dependent upon DNA PK. These results identify a novel feedback loop, where loss of E6AP results in upregulation of p53, leading to increased levels of E6 phosphorylation, which in turn correlates with increased association with 14-3-3 and inhibition of p53 transcriptional activity. IMPORTANCE This study demonstrates that the knockdown of E6AP from cervical cancer-derived cells leads to an increase in phosphorylation of the E6 oncoprotein. We show that this phosphorylation of E6 requires p53 transcriptional activity and the enzyme DNA PK. This study therefore defines a feedback loop whereby activation of p53 can induce phosphorylation of E6 and which in turn can inhibit p53 transcriptional activity, independently of E6's ability to target p53 for degradation.

Nanotechnology-Based Weapons to Combat Human Papillomavirus Infection Associated Diseases

Persistent human papillomavirus (HPV) infection will eventually lead to clinical problems, varying from verrucous lesions to malignancies like cervical cancer, oral cancer, anus cancer, and so on. To address the aforementioned problems, nanotechnology-based strategies have been applied to detect the virus, prevent the interaction between virus and mammalian cells, and treat the virus-infected cells, due mainly to the unique physicochemical properties of nanoparticles. In this regard, many nanotechnology-based chemotherapies, gene therapy, vaccination, or combination therapy have been developed. In this Minireview, we outline the pathogenesis of HPV infection and the recent advances in nanotechnology-based weapons that can be applied in combating HPV-associated diseases.

HPV and Recurrent Respiratory Papillomatosis: A Brief Review

Recurrent Respiratory Papillomatosis (RRP) is a rare but severe manifestation of human papillomavirus (HPV). As our knowledge about HPV infections has expanded, it has become possible to understand the course of RRP disease and unravel plausible efficient methods to manage the disease. However, the surge in reports on HPV has not been accompanied by a similar increase in research about RRP specifically. In this paper, we review the clinical manifestation and typical presentation of the illness. In addition, the pathogenesis and progression of the disease are described. On the other hand, we discuss the types of treatments currently available and future treatment strategies. The role of vaccination in both the prevention and treatment of RRP will also be reviewed. We believe this review is essential to update the general knowledge on RRP with the latest information available to date to enhance our understanding of RRP and its management.

Target-binding behavior of IDPs via pre-structured motifs

Pre-Structured Motifs (PreSMos) are transient secondary structures observed in many intrinsically disordered proteins (IDPs) and serve as protein target-binding hot spots. The prefix "pre" highlights that PreSMos exist a priori in the target-unbound state of IDPs as the active pockets of globular proteins pre-exist before target binding. Therefore, a PreSMo is an "active site" of an IDP; it is not a spatial pocket, but rather a secondary structural motif. The classical and perhaps the most effective approach to understand the function of a protein has been to determine and investigate its structure. Ironically or by definition IDPs do not possess structure (here structure refers to tertiary structure only). Are IDPs then entirely structureless? The PreSMos provide us with an atomic-resolution answer to this question. For target binding, IDPs do not rely on the spatial pockets afforded by tertiary or higher structures. Instead, they utilize the PreSMos possessing particular conformations that highly presage the target-bound conformations. PreSMos are recognized or captured by targets via conformational selection (CS) before their conformations eventually become stabilized via structural induction into more ordered bound structures. Using PreSMos, a number of, if not all, IDPs can bind targets following a sequential pathway of CS followed by an induced fit (IF). This chapter presents several important PreSMos implicated in cancers, neurodegenerative diseases, and other diseases along with discussions on their conformational details that mediate target binding, a structural rationale for unstructured proteins.

Human papillomavirus 16 L1 gene methylation as a potential biomarker for predicting anal intraepithelial neoplasia in men who have sex with men (MSM)

The human papillomavirus (HPV) 16 early promoter and L1 gene methylation were quantitatively measured using pyrosequencing assay in anal cells collected from men who have sex with men (MSM) to determine potential biomarkers for HPV-related anal cancer. The methylation patterns of HPV16 genes, including the early promoter (CpG 31, 37, 43, 52, and 58) and L1 genes (CpG 5600, 5606, 5609, 5615, 7136, and 7145), were analyzed in 178 anal samples. The samples were diagnosed as normal, anal intraepithelial neoplasia (AIN) 1, AIN2, and AIN3. Low methylation levels of the early promoter (< 10%) and L1 genes (< 20%) were found in all detected normal anal cells. In comparison, medium to high methylation (≥ 20–60%) in the early promoter was found in 1.5% (1/67) and 5% (2/40) of AIN1 and AIN2-3 samples, respectively. Interestingly, slightly increased L1 gene methylation levels (≥ 20–60%), especially at the HPV16 5’L1 regions CpGs 5600 and 5609, were demonstrated in AIN2-3 specimen. Moreover, a negative correlation between high HPV16 L1 gene methylation at CpGs 5600, 5609, 5615, and 7145 and a percentual CD4 count was found in AIN3 HIV positive cases. When comparing the methylation status of AIN2-3 to that of normal/AIN1 lesions, the results indicated the potential of using HPV16 L1 gene methylation as a biomarker for HPV-related cancer screening.

Molecular Characterization of Human Papillomavirus Type 159 (HPV159)

Human papillomavirus type 159 (HPV159) was identified in an anal swab sample and preliminarily genetically characterized by our group in 2012. Here we present a detailed molecular in silico analysis that showed that the HPV159 viral genome is 7443 bp in length and divided into five early and two late genes, with conserved functional domains and motifs, and a non-coding long control region (LCR) with significant regulatory sequences that allow the virus to complete its life cycle and infect novel host cells. HPV159, clustering into the cutaneotropic Betapapillomavirus (Beta-PV) genus, is phylogenetically most similar to HPV9, forming an individual phylogenetic group in the viral species Beta-2. After testing a large representative collection of clinical samples with HPV159 type-specific RT-PCR, in addition to the anal canal from which the first HPV159 isolate was obtained, HPV159 was further detected in other muco-cutaneous (4/181, 2.2%), mucosal (22/764, 2.9%), and cutaneous (14/554, 2.5%) clinical samples, suggesting its extensive tissue tropism. However, because very low HPV159 viral loads were estimated in the majority of positive samples, it seemed that HPV159 mainly caused clinically insignificant infections of the skin and mucosa. Using newly developed, highly sensitive HPV159-specific nested PCRs, two additional HPV159 LCR viral variants were identified. Nevertheless, all HPV159 mutations were demonstrated outside important functional domains of the LCR, suggesting that the HPV159 viral variants were most probably not pathogenically different. This complete molecular characterization of HPV159 enhances our knowledge of the genome characteristics, tissue tropism, and phylogenetic diversity of Beta-PVs that infect humans.

Interpretations on the Interaction between Protein Tyrosine Phosphatase and E7 Oncoproteins of High and Low-Risk HPV: A Computational Perception

The most prevalent and common sexually transmitted infection is caused by human papillomavirus (HPV) among sexually active women. Numerous genotypes of HPV are available, among which the major oncoproteins E6 and E7 lead to the progression of cervical cancer. The E7 oncoprotein interacts with cytoplasmic tumor suppressor protein PTPN14, which is the key regulator of cellular growth control pathways effecting the reduction of steady-state level. Disrupting the interaction between the tumor suppressor and the oncoprotein is vital to cease the development of cancer. Hence, the mechanism of interaction between E7 and tumor suppressor is explored through protein-protein and protein-ligand binding along with the conformational stability studies. The obtained results state that the LXCXE domain of HPV E7 of high and low risks binds with the tumor suppressor protein. Also, the small molecules bind in the interface of E7-PTPN14 that disrupts the interaction between the tumor suppressor and oncoprotein. These results were further supported by the dynamics simulation stating the stability over the bounded complex and the energy maintained during postdocking as well as postdynamics calculations. These observations possess an avenue in the drug discovery that leads to further validation and also proposes a potent drug candidate to treat cervical cancer caused by HPV.

Relevance of Human Papillomaviruses in Head and Neck Cancer-What Remains in 2021 from a Clinician's Point of View?

Human papillomaviruses (HPV) cause a subset of head and neck cancers (HNSCC). HPV16 predominantly signs responsible for approximately 10% of all HNSCC and over 50% of tonsillar (T)SCCs. Prevalence rates depend on several factors, such as the geographical region where patients live, possibly due to different social and sexual habits. Smoking plays an important role, with non-smoking patients being mostly HPV-positive and smokers being mostly HPV-negative. This is of unparalleled clinical relevance, as the outcome of (non-smoking) HPV-positive patients is significantly better, albeit with standard and not with de-escalated therapies. The results of the first prospective de-escalation studies have dampened hopes that similar superior survival can be achieved with de-escalated therapy. In this context, it is important to note that the inclusion of p16^INK4A (a surrogate marker for HPV-positivity) in the 8th TMN-classification has only prognostic, not therapeutic, intent. To avoid misclassification, highest precision in determining HPV-status is of utmost importance. Whenever possible, PCR-based methods, still referred to as the "gold standard”, should be used. New diagnostic antibodies represent some hope, e.g., to detect primaries and recurrences early. Prophylactic HPV vaccination should lead to a decline in HPV-driven HNSCC as well. This review discusses the above aspects in detail.

Cell-Penetrating Peptides-Based Liposomal Delivery System Enhanced Immunogenicity of Peptide-Based Vaccine against Group A Streptococcus

Peptide-based vaccine development represents a highly promising strategy for preventing Group A Streptococcus (GAS) infection. However, these vaccines need to be administered with the help of a delivery system and/or immune adjuvant. Cell-penetrating peptides (CPPs) have been used as a powerful tool for delivering various therapeutic agents, including peptides, as they can overcome the permeability barrier of cell membranes. Here, we used CPPs to deliver our lead lipopeptide-based vaccine (LCP-1). CPPs were anchored through a spacer to LCP-1-bearing multilamellar and unilamellar liposomes and administered to Swiss outbred mice. Tat47-57 conjugated to two palmitic acids via a (Gly)6 spacer (to form a liposome-anchoring moiety) was the most efficient system for triggering immune responses when combined with multilamellar liposomes bearing LCP-1. The immunostimulatory potential of a variety of other CPPs was examined following intranasal administration in mice. Among them, LCP-1/liposomes/Tat47-57 and LCP-1/liposomes/KALA induced the highest antibody titers. The antibodies produced showed high opsonic activity against clinically isolated GAS strains D3840 and GC2 203. The use of the CPP-liposome delivery system is a promising strategy for liposome-based GAS vaccine development.

Expression of miR-34a and miR-15b during the progression of cervical cancer in a murine model expressing the HPV16 E7 oncoprotein

The high-risk human papillomavirus (HR-HPV) E7 oncoprotein appears to be a major determinant for cell immortalization and transformation altering critical processes such as cell proliferation, apoptosis, and immune response. This oncoprotein plays an essential role in cervical carcinogenesis, but other cofactors such as long-term use of hormonal contraceptives are necessary to modulate the risk of cervical cancer (CC). The role of HR-HPVs in the alteration of microRNA (miRNA) levels in persistent viral infections currently remains unclear. The aim of this study was to evaluate the miR-34a and miR-15b expression levels in the murine HPV16K14E7 (K14E7) transgenic model after chronic estrogen (E₂) treatment and their involvement in CC. Interestingly, results showed that, although miR-34a expression is elevated by the HPVE7 oncogene, this expression was downregulated in the presence of both the E7 oncoprotein and chronic E₂ in cervical carcinoma. On the other hand, miR-15b expression was upregulated along cervical carcinogenesis mainly by the effect of E₂. These different changes in the expression levels of miR-34a and miR-15b along cervical carcinogenesis conduced to low apoptosis levels, high cell proliferation and finally, to cancerous cervical tissue development. In this work, we also determined the relative mRNA expression of Cyclin E2 (Ccne2), Cyclin A2 (Ccna2), and B cell lymphoma 2 (Bcl-2) (target genes of miR-34a and miR-15b); Sirtuin 1 (Sirt1), Cmyc, and Bax (miR-34a target genes); and p21/WAF1 (mir15b target gene) and the H-ras oncogene. Given the modifications in the expression levels of miR-34a and miR-15b during the development of cervical cancer, it will be useful to carry out further investigation to confirm them as molecular biomarkers of cancer.

HPV and Other Microbiota; Who's Good and Who's Bad: Effects of the Microbial Environment on the Development of Cervical Cancer-A Non-Systematic Review

Cervical cancer is responsible for around 5% of all human cancers worldwide. It develops almost exclusively from an unsolved, persistent infection of the squamocolumnar transformation zone between the endo- and ecto-cervix with various high-risk (HR) human papillomaviruses (HPVs). The decisive turning point on the way to persistent HPV infection and malignant transformation is an immune system weakened by pathobionts and oxidative stress and an injury to the cervical mucosa, often caused by sexual activities. Through these injury and healing processes, HPV viruses, hijacking activated keratinocytes, move into the basal layers of the cervical epithelium and then continue their development towards the distal prickle cell layer (Stratum spinosum). The microbial microenvironment of the cervical tissue determines the tissue homeostasis and the integrity of the protective mucous layer through the maintenance of a healthy immune and metabolic signalling. Pathological microorganisms and the resulting dysbiosis disturb this signalling. Thus, pathological inflammatory reactions occur, which manifest the HPV infection. About 90% of all women contract an HPV infection in the course of their lives. In about 10% of cases, the virus persists and cervical intra-epithelial neoplasia (CIN) develops. Approximately 1% of women with a high-risk HPV infection incur a cervical carcinoma after 10 to 20 years. In this non-systematic review article, we summarise how the sexually and microbial mediated pathogenesis of the cervix proceeds through aberrant immune and metabolism signalling via CIN to cervical carcinoma. We show how both the virus and the cancer benefit from the same changes in the immune and metabolic environment.

Restoring the DREAM Complex Inhibits the Proliferation of High-Risk HPV Positive Human Cells

High-risk (HR) human papillomaviruses are known causative agents in 5% of human cancers including cervical, ano-genital and head and neck carcinomas. In part, HR-HPV causes cancer by targeting host-cell tumor suppressors including retinoblastoma protein (pRb) and RB-like proteins p107 and p130. HR-HPV E7 uses a LxCxE motif to bind RB proteins, impairing their ability to control cell-cycle dependent transcription. E7 disrupts DREAM (Dimerization partner, RB-like, E2F and MuvB), a transcriptional repressor complex that can include p130 or p107, but not pRb, which regulates genes required for cell cycle progression. However, it is not known whether disruption of DREAM plays a significant role in HPV-driven tumorigenesis. In the DREAM complex, LIN52 is an adaptor that binds directly to p130 via an E7-like LxSxE motif. Replacement of the LxSxE sequence in LIN52 with LxCxE (LIN52-S20C) increases p130 binding and partially restores DREAM assembly in HPV-positive keratinocytes and human cervical cancer cells, inhibiting proliferation. Our findings demonstrate that disruption of the DREAM complex by E7 is an important process promoting cellular proliferation by HR-HPV. Restoration of the DREAM complex in HR-HPV positive cells may therefore have therapeutic benefits in HR-HPV positive cancers.

GBAF, a small BAF sub-complex with big implications: a systematic review

ATP-dependent chromatin remodeling by histone-modifying enzymes and chromatin remodeling complexes is crucial for maintaining chromatin organization and facilitating gene transcription. In the SWI/SNF family of ATP-dependent chromatin remodelers, distinct complexes such as BAF, PBAF, GBAF, esBAF and npBAF/nBAF are of particular interest regarding their implications in cellular differentiation and development, as well as in various diseases. The recently identified BAF subcomplex GBAF is no exception to this, and information is emerging linking this complex and its components to crucial events in mammalian development. Furthermore, given the essential nature of many of its subunits in maintaining effective chromatin remodeling function, it comes as no surprise that aberrant expression of GBAF complex components is associated with disease development, including neurodevelopmental disorders and numerous malignancies. It becomes clear that building upon our knowledge of GBAF and BAF complex function will be essential for advancements in both mammalian reproductive applications and the development of more effective therapeutic interventions and strategies. Here, we review the roles of the SWI/SNF chromatin remodeling subcomplex GBAF and its subunits in mammalian development and disease.

The E3 Ubiquitin Ligase Mind Bomb 1 Controls Adenovirus Genome Release at the Nuclear Pore Complex

Adenoviruses (AdVs) cause respiratory, ocular, and gastrointestinal tract infection and inflammation in immunocompetent people and life-threatening disease upon immunosuppression. AdV vectors are widely used in gene therapy and vaccination. Incoming particles attach to nuclear pore complexes (NPCs) of post-mitotic cells, then rupture and deliver viral DNA (vDNA) to the nucleus or misdeliver to the cytosol. Our genome-wide RNAi screen in AdV-infected cells identified the RING-type E3 ubiquitin ligase Mind bomb 1 (Mib1) as a proviral host factor for AdV infection. Mib1 is implicated in Notch-Delta signaling, ciliary biogenesis, and RNA innate immunity. Mib1 depletion arrested incoming AdVs at NPCs. Induced expression of full-length but not ligase-defective Mib1 in knockout cells triggered vDNA uncoating from NPC-tethered virions, nuclear import, misdelivery of vDNA, and vDNA expression. Mib1 is an essential host factor for AdV uncoating in human cells, and it provides a new concept for licensing virion DNA delivery through the NPC.

Werner Syndrome Protein (WRN) Regulates Cell Proliferation and the Human Papillomavirus 16 Life Cycle during Epithelial Differentiation

Human papillomaviruses recruit a host of DNA damage response factors to their viral genome to facilitate homologous recombination replication in association with the viral replication factors E1 and E2. We previously demonstrated that SIRT1 deacetylation of WRN promotes recruitment of WRN to E1-E2 replicating DNA and that WRN regulates both the levels and fidelity of E1-E2 replication. The deacetylation of WRN by SIRT1 results in an active protein able to complex with replicating DNA, but a protein that is less stable. Here, we demonstrate an inverse correlation between SIRT1 and WRN in CIN cervical lesions compared to normal control tissue, supporting our model of SIRT1 deacetylation destabilizing WRN protein. We CRISPR/Cas9 edited N/Tert-1 and N/Tert-1+HPV16 cells to knock out WRN protein expression and subjected the cells to organotypic raft cultures. In N/Tert-1 cells without WRN expression, there was enhanced basal cell proliferation, DNA damage, and thickening of the differentiated epithelium. In N/Tert-1+HPV16 cells, there was enhanced basal cell proliferation, increased DNA damage throughout the epithelium, and increased viral DNA replication. Overall, the results demonstrate that the expression of WRN is required to control the proliferation of N/Tert-1 cells and controls the HPV16 life cycle in these cells. This complements our previous data demonstrating that WRN controls the levels and fidelity of HPV16 E1-E2 DNA replication. The results describe a new role for WRN, a tumor suppressor, in controlling keratinocyte differentiation and the HPV16 life cycle.IMPORTANCE HPV16 is the major human viral carcinogen, responsible for around 3 to 4% of all cancers worldwide. Our understanding of how the viral replication machinery interacts with host factors to control/activate the DNA damage response to promote the viral life cycle remains incomplete. Recently, we demonstrated a SIRT1-WRN axis that controls HPV16 replication, and here we demonstrate that this axis persists in clinical cervical lesions induced by HPV16. Here, we describe the effects of WRN depletion on cellular differentiation with or without HPV16; WRN depletion results in enhanced proliferation and DNA damage irrespective of HPV16 status. Also, WRN is a restriction factor for the viral life cycle since replication is disrupted in the absence of WRN. Future studies will focus on enhancing our understanding of how WRN regulates viral replication. Our goal is to ultimately identify cellular factors essential for HPV16 replication that can be targeted for therapeutic gain.

The human papillomavirus E6 protein targets apoptosis-inducing factor (AIF) for degradation

Oncoprotein E6 of high-risk human papillomavirus (HPV) plays a critical role in inducing cell immortalization and malignancy. E6 downregulates caspase-dependent pathway through the degradation of p53. However, the effect of HPV E6 on other pathways is still under investigation. In the present study, we found that HPV E6 directly binds to all three forms (precursor, mature, and apoptotic) of apoptosis-inducing factor (AIF) and co-localizes with apoptotic AIF. This binding induced MG132-sensitive reduction of AIF expression in the presence of E6 derived from HPV16 (16E6), a cancer-causing type of HPV. Conversely, E6 derived from a non-cancer-causing type of HPV, HPV6 (6E6), did not reduce the levels of AIF despite its interaction with AIF. Flow cytometric analysis revealed that 16E6, but not 6E6, suppressed apoptotic AIF-induced chromatin degradation (an indicator of caspase-independent apoptosis) and staurosporine (STS, a protein kinase inhibitor)-induced apoptosis. AIF knockdown reduced STS-induced apoptosis in both of 16E6-expressing and 6E6-expressing cells; however, the reduction in 16E6-expressing cells was lower than that in 6E6-expressing cells. These findings indicate that 16E6, but not 6E6, blocks AIF-mediated apoptosis, and that AIF may represent a novel therapeutic target for HPV-induced cervical cancer.

Role of the oral microbiota in cancer evolution and progression

Bacteria identified in the oral cavity are highly complicated. They include approximately 1000 species with a diverse variety of commensal microbes that play crucial roles in the health status of individuals. Epidemiological studies related to molecular pathology have revealed that there is a close relationship between oral microbiota and tumor occurrence. Oral microbiota has attracted considerable attention for its role in in‐situ or distant tumor progression. Anaerobic oral bacteria with potential pathogenic abilities, especially Fusobacterium nucleatum and Porphyromonas gingivalis, are well studied and have close relationships with various types of carcinomas. Some aerobic bacteria such as Parvimonas are also linked to tumorigenesis. Moreover, human papillomavirus, oral fungi, and parasites are closely associated with oropharyngeal carcinoma. Microbial dysbiosis, colonization, and translocation of oral microbiota are necessary for implementation of carcinogenic functions. Various underlying mechanisms of oral microbiota‐induced carcinogenesis have been reported including excessive inflammatory reaction, immunosuppression of host, promotion of malignant transformation, antiapoptotic activity, and secretion of carcinogens. In this review, we have systemically described the impact of oral microbial abnormalities on carcinogenesis and the future directions in this field for bringing in new ideas for effective prevention of tumors.

Activating the DNA Damage Response and Suppressing Innate Immunity: Human Papillomaviruses Walk the Line

Activation of the DNA damage response (DDR) by external agents can result in DNA fragments entering the cytoplasm and activating innate immune signaling pathways, including the stimulator of interferon genes (STING) pathway. The consequences of this activation can result in alterations in the cell cycle including the induction of cellular senescence, as well as boost the adaptive immune response following interferon production. Human papillomaviruses (HPV) are the causative agents in a host of human cancers including cervical and oropharyngeal; HPV are responsible for around 5% of all cancers. During infection, HPV replication activates the DDR in order to promote the viral life cycle. A striking feature of HPV-infected cells is their ability to continue to proliferate in the presence of an active DDR. Simultaneously, HPV suppress the innate immune response using a number of different mechanisms. The activation of the DDR and suppression of the innate immune response are essential for the progression of the viral life cycle. Here, we describe the mechanisms HPV use to turn on the DDR, while simultaneously suppressing the innate immune response. Pushing HPV from this fine line and tipping the balance towards activation of the innate immune response would be therapeutically beneficial.

Canine papillomavirus type 16 associated to squamous cell carcinoma in a dog: virological and pathological findings

Papillomaviruses (PVs) are circular double-stranded DNA virus belonging to Papillomaviridae family. During the infection cycle, PVs translate proteins that can influence cell growth and differentiation, leading to epidermal hyperplasia and papillomas (warts) or malignant neoplasms. Canis familiaris papillomaviruses (CPVs) have been associated with different lesions, such as oral and cutaneous papillomatosis, pigmented plaques, and squamous cell carcinomas (SCCs). Here, we report a clinical case of a mixed bred female dog with pigmented plaques induced by CPV16 (Chipapillomavirus 2) that progressed to in situ and invasive SCCs. Gross and histological findings were characterized, and the lesions were mainly observed in ventral abdominal region and medial face of the limbs. In situ hybridization (ISH) revealed strong nuclear hybridization signals in the neoplastic epithelial cells, as well as in the keratinocytes and koilocytes of the pigmented viral plaques. The full genome of the CPV16 recovered directly from the lesions was characterized, and the phylogenetic relationships were determined. The identification of oncoprotein genes (E5, E6, and E7) by high throughput sequencing (HTS) and their expected domains are suggestive of the malignant transformation by CPV16.

The Role of Apoptin in Chicken Anemia Virus Replication

Apoptin is the Vp3 protein of chicken anemia virus (CAV), which infects the thymocytes and erythroblasts in young chickens, causing chicken infectious anemia and immunosuppression. Apoptin is highly studied for its ability to selectively induce apoptosis in human tumor cells and, thus, is a protein of interest in anti-tumor therapy. CAV apoptin is known to localize to different subcellular compartments in transformed and non-transformed cells, depending on the DNA damage response, and the phosphorylation of several identified threonine residues. In addition, apoptin interacts with molecular machinery such as the anaphase promoting complex/cyclosome (APC/C) to inhibit the cell cycle and induce arrest in G2/M phase. While these functions of apoptin contribute to the tumor-selective effect of the protein, they also provide an important fundamental framework to apoptin’s role in viral infection, pathogenesis, and propagation. Here, we reviewed how the regulation, localization, and functions of apoptin contribute to the viral life cycle and postulated its importance in efficient replication of CAV. A model of the molecular biology of infection is critical to informing our understanding of CAV and other related animal viruses that threaten the agricultural industry.

Preparation, Characterization and Diagnostic Valuation of Two Novel Anti-HPV16 E7 Oncoprotein Monoclonal Antibodies

At present, the clinical detection method of human papillomavirus (HPV) is mainly based on the PCR method. However, this method can only be used to detect HPV DNA and HPV types, and cannot be used to accurately predict cervical cancer. HPV16 E7 is an oncoprotein selectively expressed in cervical cancers. In this study, we prepared an HPV16 E7-histidine (HIS) fusion oncoprotein by using a prokaryotic expression and gained several mouse anti-HPV16 E7-HIS fusion oncoprotein monoclonal antibodies (mAbs) by using hybridoma technology. Two mAbs, 69E2 (IgG2a) and 79A11 (IgM), were identified. Immunocytochemistry, immunofluorescence, immunohistochemistry, and Western blot were used to characterize the specificity of these mAbs. The sequences of the nucleotide bases and predicted amino acids of the 69E2 and 79A11 antibodies showed that they were novel antibodies. Indirect enzyme-linked immunosorbent assay (ELISA) with overlapping peptides, indirect competitive ELISA, and 3D structural modeling showed that mAbs 69E2 and 79A11 specifically bound to the three exposed peptides of the HPV16 E7 (HPV16 E7_49–66, HPV16 E7_73–85, and HPV16 E7_91–97). We used these two antibodies (79A11 as a capture antibody and 69E2 as a detection antibody) to establish a double-antibody sandwich ELISA based on a horseradish peroxidase (HRP)-labeled mAb and tetramethylbenzidine (TMB) detection system for quantitative detection of the HPV16 E7-HIS fusion oncoprotein, however, it was not ideal. Then we established a chemiluminescence immunoassay based on a labeled streptavidin-biotin (LSAB)-ELISA method and luminol detection system—this was sufficient for quantitative detection of the HPV16 E7-HIS fusion oncogenic protein in ng levels and was suitable for the detection of HPV16-positive cervical carcinoma tissues. Collectively, we obtained two novel mouse anti-HPV16 E7 oncoprotein mAbs and established an LSAB-lumino-dual-antibody sandwich ELISA method for the detection of the HPV16 E7-HIS fusion oncogenic protein, which might be a promising method for the diagnosis of HPV16-type cervical cancers in the early stage.

Suppression of a Subset of Interferon-Induced Genes by Human Papillomavirus Type 16 E7 via a Cyclin Dependent Kinase 8-Dependent Mechanism

Persistent infection by human papillomaviruses (HPVs), small, double-stranded DNA viruses that infect keratinocytes of the squamous epithelia, can lead to the development of cervical and other cancers. The viral oncoprotein E7 contributes to viral persistence in part by regulating host gene expression through binding host transcriptional regulators, although mechanisms responsible for E7-mediated transcriptional regulation are incompletely understood. Type I IFN signaling promotes the expression of anti-viral genes, called interferon-stimulated genes (ISGs), through the phosphorylation and activation of STAT1. In this study, we have observed that the CR3 domain of E7 contributes to the episomal maintenance of viral genomes. Transcriptome analysis revealed that E7 transcriptionally suppresses a subset of ISGs but not through regulation of STAT1 activation. Instead, we discovered that E7 associates with Mediator kinase CDK8 and this is correlated with the recruitment of CDK8 to ISG promoters and reduced ISG expression. E7 fails to suppress ISGs in the absence of CDK8, indicating that CDK8 function contributes to the suppression of ISGs by E7. Altogether, E7/CDK8 association may be a novel mechanism by which E7 inhibits innate immune signaling.

Hyperbranched poly(β-amino ester) based polyplex nanopaticles for delivery of CRISPR/Cas9 system and treatment of HPV infection associated cervical cancer

Persistent high-risk HPV infection is the main factor for cervical cancer. HPV E7 oncogene plays an important role in HPV carcinogenesis. Down-regulation of E7 oncogene expression could induce growth inhibition in HPV-positive cells and thus treats HPV related cervical cancer. Here we developed a non-virus gene vector based on poly(amide-amine)-poly(β-amino ester) hyperbranched copolymer (hPPC) for the delivery of CRISPR/Cas9 system to specifically cleave HPV E7 oncogene in HPV-positive cervical cancer cells. The diameter of polyplex nanoparticles (NPs) formed by hPPCs/linear poly(β-amino ester) (PBAE) and plasmids were approximately 300 nm. These hPPCs/PBAE-green fluorescence protein plasmids polyplex NPs showed high transfection efficiency and low toxicity in cells and mouse organs. By cleaving HPV16 E7 oncogene, reducing the expression of HPV16 E7 protein and increasing intracellular retinoblastoma 1 (RB1) amount, hPPCs/PBAE-CRISPR/Cas9 therapeutic plasmids polyplex NPs, especially highly branched hPPC1-plasmids polyplex NPs, exhibited strong growth inhibition of cervical cancer cells in vitro and xenograft tumors in nude mice. Together, the hPPCs/PBAE polyplex NPs to deliver HPV16 E7 targeted CRISPR/Cas9 system in this study could potentially be applied to treat HPV-related cervical cancer.