E6 proteins from high-risk HPV, low-risk HPV, and animal papillomaviruses activate the Wnt/β-catenin pathway through E6AP-dependent degradation of NHERF1

Molecular aspects of cervical cancer: a pathogenesis update

Cervical cancer (CC) is a significant health problem, especially in low-income countries. Functional studies on the human papillomavirus have generated essential advances in the knowledge of CC. However, many unanswered questions remain. This mini-review discusses the latest results on CC pathogenesis, HPV oncogenesis, and molecular changes identified through next-generation technologies. Interestingly, the percentage of samples with HPV genome integrations correlates with the degree of the cervical lesions, suggesting a role in the development of CC. Also, new functions have been described for the viral oncoproteins E5, E6, and E7, resulting in the acquisition and maintenance of cancer hallmarks, including proliferation, immune response evasion, apoptosis, and genomic instability. Remarkably, E5 oncoprotein affects signaling pathways involved in the expression of interferon-induced genes and EGFR-induced proliferation, while E6 and E7 oncoproteins regulate the DNA damage repair and cell cycle continuity pathways. Furthermore, next-generation technologies provide vast amounts of information, increasing our knowledge of changes in the genome, transcriptome, proteome, metabolome, and epigenome in CC. These studies have identified novel molecular traits associated with disease susceptibility, degree of progression, treatment response, and survival as potential biomarkers and therapeutic targets.

LncRNA WWTR1-AS1 upregulates Notch3 through miR-136 to increase cancer cell stemness in cervical squamous cell carcinoma

BACKGROUND

This Study investigated the role of WWTR1-AS1 in cervical squamous cell carcinoma (CSCC).

RESULTS

WWTR1-AS1 expression was upregulated in CSCC tissues. WWTR1-AS1 was predicted to interact with miR-136, whereas correlation analysis revealed that there was no close correlation between WWTR1-AS1 and miR-136 across CSCC samples. Moreover, WWTR1-AS1 and miR-136 did not regulate the expression of each other. In addition, overexpression of WWTR1-AS1 increased the expression levels of Notch3, which could be targeted by miR-136. Cell stemness analysis indicated that the overexpression of WWTR1-AS1 and Notch3 increased CSCC cell stemness and the capacity of CSCC cell to grow as spheroids. Overexpression of miR-136 decreased CSCC cell stemness and reversed the effects of overexpression of WWTR1-AS1 on Notch3 in CSCC cells.

CONCLUSION

Therefore, WWTR1-AS1 may upregulate Notch3 through miR-136 to increase cancer cell stemness in CSCC.

An m1A/m6A/m5C-associated long non-coding RNA signature: Prognostic and immunotherapeutic insights into cervical cancer

BACKGROUND

Cervical cancer (CC) remains a significant clinical challenge, even though its fatality rate has been declining in recent years. Particularly in developing countries, the prognosis for CC patients continues to be suboptimal despite numerous therapeutic advances.

METHODS

Using The Cancer Genome Atlas database, we extracted CC-related data. From this, 52 methylation-related genes (MRGs) were identified, leading to the selection of a 10 long non-coding RNA (lncRNA) signature co-expressed with these MRGs. R programming was employed to filter out the methylation-associated lncRNAs. Through univariate, least absolute shrinkage and selection operator (i.e. LASSO) and multivariate Cox regression analysis, an MRG-associated lncRNA model was constructed. The established risk model was further assessed via the Kaplan-Meier method, principal component analysis, functional enrichment annotation and a nomogram. Furthermore, we explored the potential of this model with respect to guiding immune therapeutic interventions and predicting drug sensitivities.

RESULTS

The derived 10-lncRNA signature, linked with MRGs, emerged as an independent prognostic factor. Segmenting patients based on their immunotherapy responses allowed for enhanced differentiation between patient subsets. Lastly, we highlighted potential compounds for distinguishing CC subtypes.

CONCLUSIONS

The risk model, associated with MRG-linked lncRNA, holds promise in forecasting clinical outcomes and gauging the efficacy of immunotherapies for CC patients.

The effects of HPV oncoproteins on host communication networks: Therapeutic connotations

Human papillomavirus (HPV) infections are a leading cause of viral-induced malignancies worldwide, with a prominent association with cervical and head and neck cancers. The pivotal role of HPV oncoproteins, E5, E6, and E7, in manipulating cellular events, which contribute to viral pathogenesis in various ways, has been extensively documented. This article reviews the influence of HPV oncoproteins on cellular signaling pathways within the host cell, shedding light on the underlying molecular mechanisms. A comprehensive understanding of these molecular alterations is essential for the development of targeted therapies and strategies to combat HPV-induced premalignancies and prevent their progress to cancer. Furthermore, this review underscores the intricate interplay between HPV oncoproteins and some of the most important cellular signaling pathways: Notch, Wnt/β-catenin, MAPK, JAK/STAT, and PI3K AKT/mTOR. The treatment efficacies of the currently available inhibitors on these pathways in an HPV-positive context are also discussed. This review also highlights the importance of continued research to advance our knowledge and enhance therapeutic interventions for HPV-associated diseases.

Human papillomavirus associated cervical lesion: pathogenesis and therapeutic interventions

Human papillomavirus (HPV) is the most prevalent sexually transmitted virus globally. Persistent high-risk HPV infection can result in cervical precancerous lesions and cervical cancer, with 70% of cervical cancer cases associated with high-risk types HPV16 and 18. HPV infection imposes a significant financial and psychological burden. Therefore, studying methods to eradicate HPV infection and halt the progression of precancerous lesions remains crucial. This review comprehensively explores the mechanisms underlying HPV-related cervical lesions, including the viral life cycle, immune factors, epithelial cell malignant transformation, and host and environmental contributing factors. Additionally, we provide a comprehensive overview of treatment methods for HPV-related cervical precancerous lesions and cervical cancer. Our focus is on immunotherapy, encompassing HPV therapeutic vaccines, immune checkpoint inhibitors, and advanced adoptive T cell therapy. Furthermore, we summarize the commonly employed drugs and other nonsurgical treatments currently utilized in clinical practice for managing HPV infection and associated cervical lesions. Gene editing technology is currently undergoing clinical research and, although not yet employed officially in clinical treatment of cervical lesions, numerous preclinical studies have substantiated its efficacy. Therefore, it holds promise as a precise treatment strategy for HPV-related cervical lesions.

The construction of a prognostic model of cervical cancer based on four immune-related LncRNAs and an exploration of the correlations between the model and oxidative stress

Introduction: The immune-related lncRNAs (IRLs) are critical for the development of cervical cancer (CC), but it is still unclear how exactly ILRs contribute to CC. In this study, we aimed to examine the relationship between IRL and CC in detail. Methods: First, the RNAseq data and clinical data of CC patients were collected from The Cancer Genome Atlas (TCGA) database, along with the immune genes from the Import database. We used univariate cox and least absolute shrinkage and selection operator (lasso) to obtain IRLs for prediction after screening the variables. According to the expression levels and risk coefficients of IRLs, the riskscore were calculated. We analyzed the relationship between the model and oxidative stress. We stratified the risk model into two as the high and low-risk groups. We also evaluated the survival differences, immune cell differences, immunotherapeutic response differences, and drug sensitivity differences between the risk groups. Finally, the genes in the model were experimentally validated. Results: Based on the above analyses, we further selected four IRLs (TFAP2A.AS1, AP000911.1, AL133215.2, and LINC02078) to construct the risk model. The model was associated with oxidative-stress-related genes, especially SOD2 and OGG1. Patients in the high-risk group had a lower overall survival than those in the low-risk group. Riskscore was positively correlated with resting mast cells, neutrophils, and CD8+ T-cells. Patients in the low-risk group showed a greater sensitivity to immunosuppression therapy. In addition, we found that patients with the PIK3CA mutation were more sensitive to chemotherapeutic agents such as dasatinib, afatinib, dinaciclib and pelitinib. The function of AL133215.2 was verified, which was consistent with previous findings, and AL133215.2 exerted a pro-tumorigenic effect. We also found that AL133215.2 was closely associated with oxidative-stress-related pathways. Discussion: The results suggested that risk modeling might be useful for prognosticating patients with CC and opening up new routes for immunotherapy.

HPV E6 inhibits E6AP to regulate epithelial homeostasis by modulating keratinocyte differentiation commitment and YAP1 activation

Human papillomaviruses (HPV) cause persistent infections by modulating epithelial homeostasis in cells of the infected basal layer. Using FUCCI and cell-cell competition assays, we have identifed regulatory roles for E6AP and NHERF1, which are the primary HPV11 E6 cellular targets, as well as being targets of the high-risk E6 proteins, in processes governing epithelial homeostasis (i.e. cell density, cell cycle entry, commitment to differentiation and basal layer delamination). Depletion of E6AP, or expression of HPV11 or 16E6 increased keratinocyte cell density and cell cycle activity, and delayed the onset of differentiation; phenotypes which were conspicuously present in HPV11 and 16 infected patient tissue. In line with proposed E6 functions, in HPV11 condyloma tissue, E6AP and NHERF1 were significantly reduced when compared to uninfected epithelium. In experimental systems, loss of HPV11 E6/E6AP binding abolished 11E6's homeostasis regulatory functions, while loss of E6/NHERF1 binding reduced the cell density threshold at which differentiation was triggered. By contrast, a NHERF1-binding mutant of 16E6 was not compromised in its homeostasis functions, while E6AP appeared essential. RNA sequencing revealed similar transcriptional profiles in both 11 and 16E6-expressing cells and E6AP-/- cells, with YAP target genes induced, and keratinocyte differentiation genes being downregulated. HPV11 E6-mediated Yap activation was observed in 2D and 3D (organotypic raft) cell culture systems and HPV-infected lesions, with both NHERF1, which is a regulator of the Hippo and Wnt pathways, and E6AP, playing an important role. As the conserved binding partner of Alpha group HPV E6 proteins, the precise role of E6AP in modulating keratinocyte phenotype and associated signalling pathways has not previously been defined. Our study suggests a model in which the preserved functions of the low and high-risk Alpha E6 proteins modulate epithelial homeostasis via E6AP activity, and lead to alteration of multiple downstream pathways, including those involving NHERF1 and YAP.

HPV E6 promotes cell proliferation of cervical cancer cell by accelerating accumulation of RBM15 dependently of autophagy inhibition

The mechanism of m6A modification in HPV-related cervical cancer remains unclear. This study explored the role of methyltransferase components in HPV-related cervical cancer and the mechanism. The levels of methyltransferase components and autophagy, ubiquitylation of RBM15 protein and the co-localization of lysosomal markers LAMP2A and RBM15 were measured. CCK-8 assay, flow cytometry, clone formation experiment and immunofluorescence assay were conducted to measure cell proliferation. The mouse tumor model was developed to study the cell growth in vivo. The binding of RBM15 to c-myc mRNA and m6A modifcation of c-myc mRNA were analyzed. The expressions of METTL3, RBM15 and WTAP were higher in HPV-positive cervical cancer cell lines than those in HPV-negative cells, especially RBM15. HPV-E6 knock-down inhibited the expression of RBM15 protein and promoted its degradation, but couldn't change its mRNA level. Autophagy inhibitor and proteasome inhibitor could reverse those effects. HPV-E6 siRNA could not enhance ubiquitylation modification of RBM15, but could enhance autophagy and the co-localization of RBM15 and LAMP2A. RBM15 overexpression could enhance cell proliferation, block the inhibitory effects of HPV-E6 siRNA on cell growth, and these effects could be reserved by cycloeucine. RBM15 could bind to c-myc mRNA, resulting in an increase to m6A level and protein expression of c-myc, which could be blocked by cycloeucine. HPV-E6 can downregulate autophagy, inhibit the degradation of RBM15 protein, induce the accumulation of intracellular RBM15, and increase the m6A modification on c-myc mRNA, resulting in an increase of c-myc protein and a growth promotion for cervical cancer cells.

Additive energetic contributions of multiple peptide positions determine the relative promiscuity of viral and human sequences for PDZ domain targets

Protein-protein interactions that involve recognition of short peptides are critical in cellular processes. Protein-peptide interaction surface areas are relatively small and shallow, and there are often overlapping specificities in families of peptide-binding domains. Therefore, dissecting selectivity determinants can be challenging. PDZ domains are a family of peptide-binding domains located in several intracellular signaling and trafficking pathways. These domains are also directly targeted by pathogens, and a hallmark of many oncogenic viral proteins is a PDZ-binding motif. However, amidst sequences that target PDZ domains, there is a wide spectrum in relative promiscuity. For example, the viral HPV16 E6 oncoprotein recognizes over double the number of PDZ domain-containing proteins as the cystic fibrosis transmembrane conductance regulator (CFTR) in the cell, despite similar PDZ targeting-sequences and identical motif residues. Here, we determine binding affinities for PDZ domains known to bind either HPV16 E6 alone or both CFTR and HPV16 E6, using peptides matching WT and hybrid sequences. We also use energy minimization to model PDZ-peptide complexes and use sequence analyses to investigate this difference. We find that while the majority of single mutations had marginal effects on overall affinity, the additive effect on the free energy of binding accurately describes the selectivity observed. Taken together, our results describe how complex and differing PDZ interactomes can be programmed in the cell.

Additive energetic contributions of multiple peptide positions determine the relative promiscuity of viral and human sequences for PDZ domain targets

Protein-protein interactions that include recognition of short sequences of amino acids, or peptides, are critical in cellular processes. Protein-peptide interaction surface areas are relatively small and shallow, and there are often overlapping specificities in families of peptide-binding domains. Therefore, dissecting selectivity determinants can be challenging. PDZ domains are an example of a peptide-binding domain located in several intracellular signaling and trafficking pathways, which form interactions critical for the regulation of receptor endocytic trafficking, tight junction formation, organization of supramolecular complexes in neurons, and other biological systems. These domains are also directly targeted by pathogens, and a hallmark of many oncogenic viral proteins is a PDZ-binding motif. However, amidst sequences that target PDZ domains, there is a wide spectrum in relative promiscuity. For example, the viral HPV16 E6 oncoprotein recognizes over double the number of PDZ domain-containing proteins as the cystic fibrosis transmembrane conductance regulator (CFTR) in the cell, despite similar PDZ targeting-sequences and identical motif residues. Here, we determine binding affinities for PDZ domains known to bind either HPV16 E6 alone or both CFTR and HPV16 E6, using peptides matching WT and hybrid sequences. We also use energy minimization to model PDZ-peptide complexes and use sequence analyses to investigate this difference. We find that while the majority of single mutations had a marginal effect on overall affinity, the additive effect on the free energy of binding accurately describes the selectivity observed. Taken together, our results describe how complex and differing PDZ interactomes can be programmed in the cell.

Alteration of Na/H exchange regulatory factor-1 protein levels in anogenital lesions positive for mucosal high-risk human papillomavirus type 16

Mucosal high-risk (HR) human papillomaviruses (HPV) are associated with anogenital carcinogenesis. The products of two early genes, E6 and E7, act as major viral oncoproteins. Functional studies in experimental models showed that HPV16 E6 induces degradation of the PDZ protein, the Na+/H+ exchanger regulatory factor-1 (NHERF-1). Here, we determined NHERF-1 protein levels by immunohistochemistry (IHC) in (i) benign anogenital warts (n = 8) (ii) premalignant lesions (L-SIL and H-SIL) (n = 43) and (iii) invasive cervical squamous cell carcinomas (SCC) (n = 17). A decrease of NHERF-1 protein level was not observed in genital warts in comparison to healthy epithelium. Conversely, a clearly decrease in NHERF-1 protein levels was observed in HPV16-positive pre-malignant and malignant lesions, while the phenomenon was much attenuated in lesions induced by other HR HPV types. In conclusion, these findings show that mucosal HPV types differently impact on NHERF-1 protein level in benign and malignant anogenital lesions.

Human papillomavirus type 16 E6 induces cell competition

High-risk human papillomavirus (HPV) infections induce squamous epithelial tumors in which the virus replicates. Initially, the virus-infected cells are untransformed, but expand in both number and area at the expense of uninfected squamous epithelial cells. We have developed an in vitro assay in which colonies of post-confluent HPV16 expressing cells outcompete and displace confluent surrounding uninfected keratinocytes. The enhanced colony competition induced by the complete HPV16 genome is conferred by E6 expression alone, not by individual expression of E5 or E7, and requires E6 interaction with p53. E6-expressing keratinocytes undermine and displace adjacent normal keratinocytes from contact with the attachment substrate, thereby expanding the area of the E6-expressing colony at the expense of normal keratinocytes. These new results separate classic oncogenicity that is primarily conferred by HPV16 E7 from cell competition that we show is primarily conferred by E6 and provides a new biological role for E6 oncoproteins from high-risk human papillomaviruses.

Microbial infections can change the fate and behavior of normal vertebrate cells to resemble oncogenic cells. High-risk papillomaviruses induce infected squamous epithelial cells to form tumors, some of which evolve into malignancies. The present work shows that the enhanced competitiveness of HPV16-infected cells for the basal cell surface is primarily due to the expression of the E6 oncoprotein and not the E7 or E5 oncoproteins. Compared to normal keratinocytes, E6 induces a super-competitor phenotype while E5 and E7 do not. This work shows the importance of measuring oncoprotein traits not only as cell autonomous traits, but in the context of competition with uninfected cells and shows the potential of papillomavirus oncoproteins to be novel genetic probes for the analysis of cell competition.

The Biological Relevance of NHERF1 Protein in Gynecological Tumors

Gynecological cancer management remains challenging and a better understanding of molecular mechanisms that lead to carcinogenesis and development of these diseases is needed to improve the therapeutic approaches. The Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein that contains modular protein-interaction domains able to interact with molecules with an impact on carcinogenesis and cancer progression. During recent years, its involvement in gynecological cancers has been explored, suggesting that NHERF1 could be a potential biomarker for the development of new targeted therapies suitable to the management of these tumors. This comprehensive review provides an update on the recent study on NHERF1 activity and its pathological role in cervical and ovarian cancer, as well as on its probable involvement in the therapeutic landscape of these cancer types.

Infection by High-Risk Human Papillomaviruses, Epithelial-to-Mesenchymal Transition and Squamous Pre-Malignant or Malignant Lesions of the Uterine Cervix: A Series of Chained Events?

Wound healing requires static epithelial cells to gradually assume a mobile phenotype through a multi-step process termed epithelial-to-mesenchymal transition (EMT). Although it is inherently transient and reversible, EMT perdures and is abnormally activated when the epithelium is chronically exposed to pathogens: this event deeply alters the tissue and eventually contributes to the development of diseases. Among the many of them is uterine cervical squamous cell carcinoma (SCC), the most frequent malignancy of the female genital system. SCC, whose onset is associated with the persistent infection of the uterine cervix by high-risk human papillomaviruses (HR-HPVs), often relapses and/or metastasizes, being resistant to conventional chemo- or radiotherapy. Given that these fearsome clinical features may stem, at least in part, from the exacerbated and long-lasting EMT occurring in the HPV-infected cervix; here we have reviewed published studies concerning the impact that HPV oncoproteins, cellular tumor suppressors, regulators of gene expression, inflammatory cytokines or growth factors, and the interactions among these effectors have on EMT induction and cervical carcinogenesis. It is predictable and desirable that a broader comprehension of the role that EMT inducers play in SCC pathogenesis will provide indications to flourish new strategies directed against this aggressive tumor.

ERa-36 instead of ERa mediates the stimulatory effects of estrogen on the expression of viral oncogenes HPV E6/E7 and the malignant phenotypes in cervical cancer cells

High risk human papillomavirus (HPV) is the main causative factor of cervical cancer. In addition, estrogen and its receptors are also involved in the development of carcinogenesis. The canonical estrogen receptor ERα is frequently deficient while its variant ERα-36 is highly expressed in cervical cancer cells. The biological significance for this receptor transition from ERα to ERα-36 remains unclear. In the present study, the results of RT-PCR and Western blot demonstrated that ERα and ERα-36 function antagonistically on the expression of the viral oncogenes HPV E6 and E7. At mRNA and protein levels, ERα inhibited HPV E6/E7 expression whereas ERα-36 stimulated HPV E6/E7 expression. Overexpression of ERα-36 promoted cell proliferation while reintroduction of ERα into cervical cancer cells did not significantly affect cell proliferation which is in line with the different effects of . ERα-36 and ERα on the expression of cell cycle regulator, namely p53, p21 and cyclin D1. Furthermore, ERα suppressed whereas ERα-36 promoted the migration and invasion of cervical cancer cells, which should be related to the oppositive roles of ERα and ERα-36 in the Wnt/β-catenin/MRTF-A signaling pathway which is activated by HPV E7. Results of this study suggest that ERα functions as a tumor suppressor whereas ERα-36 is an oncoprotein in cervical cancer cells. ERα deficiency together with ERα-36 overexpression might enhance the expression of HPV E6/E7 genes and facilitate the development of cervical cancer. Targeting ERα-36 with selective antagonists should be a promising strategy for cervical cancer therapy.

The biology of papillomavirus PDZ associations: what do they offer papillomaviruses?

The high-risk α-type papillomaviruses have a C-terminal PDZ-binding motif (PBM) on one of the two major oncoproteins E6 or E7; the vast majority on E6. The PBM is essential for the high-risk HPV life cycle, for episomal maintenance of the virus genome, and for maintaining the mitotic stability of the infected cell. The question is why only these viruses have PBMs - are there specific constraints imposed by the mucosal epithelium in which these viruses replicate? However the low-risk α-HPVs, such as HPV-6 and HPV-11 replicate extremely efficiently without a PBM, while viruses of the alpha8 group, such as HPV-40, replicate well with a very primitive PBM. So what does PDZ-binding capacity contribute to the fitness of the virus?

Implications of viral infection in cancer development

Since the identification of the first human oncogenic virus in 1964, viruses have been studied for their potential role in aiding the development of cancer. Through the modulation of cellular pathways associated with proliferation, immortalization, and inflammation, viral proteins can mimic the effect of driver mutations and contribute to transformation. Aside from the modulation of signaling pathways, the insertion of viral DNA into the host genome and the deregulation of cellular miRNAs represent two additional mechanisms implicated in viral oncogenesis. In this review, we will discuss the role of twelve different viruses on cancer development and how these viruses utilize the abovementioned mechanisms to influence oncogenesis. The identification of specific mechanisms behind viral transformation of human cells could further elucidate the process behind cancer development.

Human papillomavirus E6 and E7: What remains?

Decades of research on the human papillomavirus oncogenes, E6 and E7, have given us huge amounts of data on their expression, functions and structures. We know much about the very many cellular proteins and pathways that they influence in one way or another. However, much of this information is quite discrete, referring to one activity examined under one condition. It is now time to join the dots to try to understand a larger picture: how, where and when do all these interactions occur... and why? Examining these questions will also show how many of the yet obscure cellular processes work together for cellular and tissue homeostasis in health and disease.

Host PDZ-containing proteins targeted by SARS-CoV-2

Small linear motifs targeting protein interacting domains called PSD‐95/Dlg/ZO‐1 (PDZ) have been identified at the C terminus of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) proteins E, 3a, and N. Using a high‐throughput approach of affinity‐profiling against the full human PDZome, we identified sixteen human PDZ binders of SARS‐CoV‐2 proteins E, 3A, and N showing significant interactions with dissociation constants values ranging from 3 to 82 μm. Six of them (TJP1, PTPN13, HTRA1, PARD3, MLLT4, LNX2) are also recognized by SARS‐CoV while three (NHERF1, MAST2, RADIL) are specific to SARS‐CoV‐2 E protein. Most of these SARS‐CoV‐2 protein partners are involved in cellular junctions/polarity and could be also linked to evasion mechanisms of the immune responses during viral infection. Among the binders of the SARS‐CoV‐2 proteins E, 3a, or N, seven significantly affect viral replication under knock down gene expression in infected cells. This PDZ profiling identifying human proteins potentially targeted by SARS‐CoV‐2 can help to understand the multifactorial severity of COVID19 and to conceive effective anti‐coronaviral agents for therapeutic purposes.

miR-4417 targets lncRNA PSMG3-AS1 to suppress cell invasion and migration in cervical squamous cell carcinoma

Although long non-coding RNA (lncRNA) PSMG3-AS1 has been reported to participate in cancer biology, its role in cervical squamous cell carcinoma (CSCC) is unknown. The present study aimed to investigate the role of the lncRNA PSMG3-AS1 in CSCC. The expression levels of PSMG3-AS1 in both CSCC and non-tumor tissues from 64 patients with CSCC were measured by reverse transcription-quantitative PCR. The potential interaction between miR-4417 and PSMG3-AS1 was predicted using IntaRNA 2.0. Overexpression of miR-4417 and PSMG3-AS1 were achieved in CSCC cells to further explore the potential interaction between them. The effects of overexpression of miR-4417 and PSMG3-AS1 on CSCC cell invasion and migration were assessed by Transwell assay. The results revealed that PSMG3-AS1 expression was upregulated in CSCC tissues, and its high expression levels predicted a poor survival in patients with CSCC. miR-4417 expression was downregulated in CSCC tissues and was inversely correlated with PSMG3-AS1 expression. Moreover, miR-4417 was predicted to interact with PSMG3-AS1. In CSCC cells, overexpression of miR-4417 decreased the expression levels of PSMG3-AS1, while overexpression of PSMG3-AS1 did not affect miR-4417 expression. Transwell assay demonstrated that overexpression of PSMG3-AS1 increased CSCC cell invasion and migration. However, overexpression of miR-4417 inhibited CSCC cell invasion and migration, and attenuated the effects of PSMG3-AS1 overexpression in CSCC cells. In conclusion, the present study indicated that miR-4417 may target PSMG3-AS1 to suppress cancer cell invasion and migration in CSCC.

LncRNA MCM3AP-AS1 inhibits cell proliferation in cervical squamous cell carcinoma by down-regulating miRNA-93

Background: MCM3AP antisense RNA 1 (MCM3AP-AS1) is characterized as an oncogenic lncRNA in hepatocellular carcinoma and glioblastoma. We analyzed TCGA dataset and observed the down-regulation of MCM3AP-AS1 in cervical squamous cell carcinoma (CSCC). The present study was therefore performed to investigate the role of MCM3AP-AS1 in CSCC.

Methods: A total of 64 female patients with CSCC (38–68 years old; mean age: 53.1 ± 6.5 years old) were enrolled in the present study. RT-qPCR was performed to evaluate gene expression. Methylation specific PCR (MSP) was performed to assess the methylation of miR-93 gene after the overexpression and silencing of MCM3AP-AS1. Cell transfections were performed to investigate the interactions between MCM3AP-AS1 and miR-93. Cell proliferation was assessed by CCK-8 assay.

Results: The results showed that MCM3AP-AS1 was down-regulated in CSCC and predicted poor survival. The expression levels of MCM3AP-AS1 were inversely correlated with the expression levels of miR-93. Overexpression of MCM3AP-AS1 led to down-regulation of miR-93, while silencing of MCM3AP-AS1 played an opposite role in CSCC cells. Methylation-specific PCR revealed that MCM3AP-AS1 could positively regulate the methylation of miR-93 gene. Cell proliferation analysis showed that overexpression of MCM3AP-AS1 led to reduced proliferation rate of CSCC cells. Silencing of MCM3AP-AS1 played an opposite role and overexpression of miR-93 reduced the effects of overexpressing MCM3AP-AS1.

Conclusions: Therefore, MCM3AP-AS1 may inhibit cell proliferation in CSCC by down-regulating miRNA-93.

Therapeutic strategies of different HPV status in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the 9^th most common malignant tumor in the world. Based on the etiology, HNSCC has two main subtypes: human papillomavirus (HPV) -related and HPV-unrelated. HPV-positive HNSCC is more sensitive to treatment with favorable survival. Due to the different biological behaviors, individual therapy is necessary and urgently required to deduce the therapeutic intensity of HPV-positive disease and look for a more effective and toxicity-acceptable regimen for HPV-negative disease. EGFR amplification and PI3K/AKT/mTOR pathway aberrant activation are quite common in HPV-positive HNSCC. Besides, HPV infection alters immune cell infiltrating in HNSCC and encompasses a diverse and heterogeneous landscape with more immune infiltration. On the other hand, the chance of HPV-negative cancers harboring mutation on the P53 gene is significantly higher than that of HPV-positive disease. This review focuses on the updated preclinical and clinical data of HPV-positive and HPV-negative HNSCC and discusses the therapeutic strategies of different HPV status in HNSCC.

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.

Structure of High-Risk Papillomavirus 31 E6 Oncogenic Protein and Characterization of E6/E6AP/p53 Complex Formation

The degradation of p53 is a hallmark of high-risk human papillomaviruses (HPVs) of the alpha genus and HPV-related carcinogenicity. The oncoprotein E6 forms a ternary complex with the E3 ubiquitin ligase E6-associated protein (E6AP) and tumor suppressor protein p53 targeting p53 for ubiquitination. The extent of p53 degradation by different E6 proteins varies greatly, even for the closely related HPV16 and HPV31. HPV16 E6 and HPV31 E6 display high sequence identity (∼67%). We report here, for the first time, the structure of HPV31 E6 bound to the LxxLL motif of E6AP. HPV16 E6 and HPV31 E6 are structurally very similar, in agreement with the high sequence conservation. Both E6 proteins bind E6AP and degrade p53. However, the binding affinities of 31 E6 to the LxxLL motif of E6AP and p53, respectively, are reduced 2-fold and 5.4-fold compared to 16 E6. The affinity of E6-E6AP-p53 ternary complex formation parallels the efficacy of the subsequent reaction, namely, degradation of p53. Therefore, closely related E6 proteins addressing the same cellular targets may still diverge in their binding efficiencies, possibly explaining their different phenotypic or pathological impacts.IMPORTANCE Variations of carcinogenicity of human papillomaviruses are related to variations of the E6 and E7 interactome. While different HPV species and genera are known to target distinct host proteins, the fine differences between E6 and E7 of closely related HPVs, supposed to target the same cellular protein pools, remain to be addressed. We compare the oncogenic E6 proteins of the closely related high-risk HPV31 and HPV16 with regard to their structure and their efficiency of ternary complex formation with their cellular targets p53 and E6AP, which results in p53 degradation. We solved the crystal structure of 31 E6 bound to the E6AP LxxLL motif. HPV16 E6 and 31 E6 structures are highly similar, but a few sequence variations lead to different protein contacts within the ternary complex and, as quantified here, an overall lower binding affinity of 31 E6 than 16 E6. These results align with the observed lower p53 degradation potential of 31 E6.

Six-lncRNA Immune Prognostic Signature for Cervical Cancer

Background

This study searched for immune-related long noncoding RNAs (lncRNAs) to predict the prognosis of patients with cervical cancer.

Method

We obtained immunologically relevant lncRNA expression profiles and clinical follow-up data from cervical cancer patients from The Cancer Genome Atlas database and the Molecular Signatures Database. Cervical cancer patients were randomly divided into a training group, testing group and combined group. The immune prognostic signature was constructed by Least Absolute Shrinkage and Selection Operator Cox regression, prognosis was analyzed by Kaplan-Meier curves between different groups, and the accuracy of the prognostic model was assessed by receiver operating characteristic-area under the curve (ROC-AUC) analysis.

Results

A six-lncRNA immune prognostic signature (LIPS) was constructed to predict the prognosis of cervical cancer. The six lncRNAs are as follows: AC009065.8, LINC01871, MIR210HG, GEMIN7-AS1, GAS5-AS1, and DLEU1. A ROC-AUC analysis indicated that the model could predict the prognosis of cervical cancer patients in different subgroups. A Kaplan-Meier analysis showed that patients with high risk scores had a poor prognosis; these results were equally meaningful in the subgroup analyses. Risk scores differed depending on the clinical pathology and tumor grade and were independent risk factors for cervical cancer prognosis. Gene set enrichment analysis revealed an association between the LIPS and the immune response, Wnt signaling pathway, and TGF beta signaling pathway.

Conclusion

Our study shows that the six-LIPS can predict the prognosis of cervical cancer and contribute to decisions regarding the immunotherapeutic strategy.

A ubiquitin variant-based affinity approach selectively identifies substrates of the ubiquitin ligase E6AP in complex with HPV-11 E6 or HPV-16 E6

The E6 protein of both mucosal high-risk human papillomaviruses (HPVs) such as HPV-16, which have been causally associated with malignant tumors, and low-risk HPVs such as HPV-11, which cause the development of benign tumors, interacts with the cellular E3 ubiquitin ligase E6-associated protein (E6AP). This indicates that both HPV types employ E6AP to organize the cellular proteome to viral needs. However, whereas several substrate proteins of the high-risk E6-E6AP complex are known, e.g. the tumor suppressor p53, potential substrates of the low-risk E6-E6AP complex remain largely elusive. Here, we report on an affinity-based enrichment approach that enables the targeted identification of potential substrate proteins of the different E6-E6AP complexes by a combination of E3-selective ubiquitination in whole-cell extracts and high-resolution MS. The basis for the selectivity of this approach is the use of a ubiquitin variant that is efficiently used by the E6-E6AP complexes for ubiquitination but not by E6AP alone. By this approach, we identified ∼190 potential substrate proteins for low-risk HPV-11 E6 and high-risk HPV-16 E6. Moreover, subsequent validation experiments in vitro and within cells with selected substrate proteins demonstrate the potential of our approach. In conclusion, our data represent a reliable repository for potential substrates of the HPV-16 and HPV-11 E6 proteins in complex with E6AP.

High-Risk HPV Oncoproteins and PD-1/PD-L1 Interplay in Human Cervical Cancer: Recent Evidence and Future Directions

Cervical cancer is the fourth most common malignancy in women worldwide and a leading cause of cancer-related mortality in developing countries. Important etiological factors in this cancer are high-risk human papillomaviruses (HPV), as roughly 96% of cervical cancer cases are positive for these oncoviruses. On the other hand, it has been recently pointed out that E6/E7 oncoproteins of high-risk HPV can upregulate the programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) axis. Likewise, several recent reports showed that checkpoint blockades targeting PD-1/PD-L1 pathways have achieved efficient clinical responses via suppressing cancer progression and improving survival in several types of human cancers including metastatic cervical cancer. In this review, we summarize recent advances in our understanding of the PD-1/PD-L1 signaling pathway and its interaction with high-risk HPV and their oncoproteins, which could have an important impact on the management of HPV-associated cancers including cervical.

Inferring Virus-Host relationship between HPV and its host Homo sapiens using protein interaction network

Human papilloma virus (HPV) is a serious threat to human life globally with over 100 genotypes including cancer causing high risk HPVs. Study on protein interaction maps of pathogens with their host is a recent trend in ‘omics’ era and has been practiced by researchers to find novel drug targets. In current study, we construct an integrated protein interaction map of HPV with its host human in Cytoscape and analyze it further by using various bioinformatics tools. We found out 2988 interactions between 12 HPV and 2061 human proteins among which we identified MYLK, CDK7, CDK1, CDK2, JAK1 and 6 other human proteins associated with multiple viral oncoproteins. The functional enrichment analysis of these top-notch key genes is performed using KEGG pathway and Gene Ontology analysis, which reveals that the gene set is enriched in cell cycle a crucial cellular process, and the second most important pathway in which the gene set is involved is viral carcinogenesis. Among the viral proteins, E7 has the highest number of associations in the network followed by E6, E2 and E5. We found out a group of genes which is not targeted by the existing drugs available for HPV infections. It can be concluded that the molecules found in this study could be potential targets and could be used by scientists in their drug design studies.

LncRNA LUADT1 Promotes Oral Squamous Cell Carcinoma Cell Proliferation by Regulating miR-34a/GAS1 Axis

Introduction

The oncogenic role of lncRNA LUADT1 has been investigated only in lung cancer. This study aimed to investigate the role of LUADT1 in oral squamous cell carcinoma (OSCC).

Patients and Methods

The expression levels of LUADT1 in paired OSCC and non-tumor tissues from OSCC patients were determined by RT-qPCR. A 5-year follow-up study was performed to analyze the prognostic value of LUADT1 for OSCC. Dual-luciferase assay and overexpression experiments were performed to assess the interactions among LUADT1, miR-34a and GASL1. Cell proliferation was analyzed by cell proliferation assay.

Results

In this study, we found that LUADT1 was upregulated in OSCC and predicted poor survival. LUADT1 was predicted to interact with miR-34a, which was confirmed by dual-luciferase activity assay. However, overexpression experiments showed that they did not affect the expression of each other. Interestingly, overexpression of LUADT1 resulted in upregulation of GAS1, a target of miR-34a. Cell proliferation assay revealed that overexpression of LUADT1 and GAS1 resulted in promoted cell proliferation. MiR-34a played an opposite role and reversed the effects of LUADT1 overexpression.

Conclusion

LUADT1 may promote OSCC proliferation by regulating miR-34a/GAS1 axis.

Human Papillomavirus E6/E7 Expression in Preeclampsia-Affected Placentae

Whether HPV is causative of pregnancy complications is uncertain. E6 and E7 affect functions underling preeclampsia (PET) in cultured trophoblasts, but whether E6 and E7 is produced in the placenta is uncertain. Here, we investigated whether E6/E7 was expressed in the placentae from pregnancies with PET, other pregnancy complications (fetal growth restriction (FGR) and diabetes mellitus), and uncomplicated pregnancies. Placental tissues collected from two geographical locations were subjected to RNAscope analyses of high- and low- risk E6/E7, and individual HPV types identified using an HPV array. High-risk E6/E7 expression was increased in both PET cohorts, (81% and 86% of patients positive for high-risk HPV DNA compared to 13% of control patients). Various HPV types were identified. Although HPV 18 was the most frequent in all cohorts, the majority of individuals had multiple HPV types (55% of the PET compared to 25% of the control cohort). Further evidence that E6 and E7 is present early when placental pathology underlying preeclampsia is established, is provided with the finding of high-risk E6/E7 in the first-trimester placenta anchoring trophoblast. In conclusion, E6/E7 expression and multiple HPV types were frequent in placentae from preeclampsia-complicated pregnancies.

lncRNA NR2F1-AS1 Regulates miR-17/SIK1 Axis to Suppress the Invasion and Migration of Cervical Squamous Cell Carcinoma Cells

lncRNA NR2F1-AS1 has been reported to be upregulated in hepatocellular carcinoma and plays oncogenic roles. Through the analysis of TCGA dataset, we observed the downregulation of NR2F1-AS1 in cervical squamous cell carcinoma (CSCC). This study was performed to analyze the functionality of NR2F1-AS1 in CSCC. It was observed that NR2F1-AS1 was significantly downregulated in tumor tissues than in paired non-tumor tissues in CSCC patients. Levels of NR2F1-AS1 decreased with increased in clinical stages. NR2F1-AS1 can directly interact with miR-17. Overexpression experiments showed that NR2F1-AS1 and miR-17 have no significant effects on the expression of each other. Interestingly, NR2F1-AS1 overexpression led to the upregulation of SIK1, a target of miR-17. Transwell assay analysis revealed decreased invasion and migration rates of CSCC cells after NR2F1-AS1 and SIK1 overexpression. miR-17 overexpression played an opposite role and reduced the effects of NR2F1-AS1 and SIK1 overexpression. Therefore, NR2F1-AS1 regulates miR-17/SIK1 axis to suppress the invasion and migration of CSCC cells.

Multiple regions of E6AP (UBE3A) contribute to interaction with papillomavirus E6 proteins and the activation of ubiquitin ligase activity

The HECT domain E3 ubiquitin ligase E6AP (UBE3A) is critical for the development of human papillomavirus (HPV) associated cancers, the neurodevelopment disorder Angelman Syndrome, and some cases of autism spectrum disorders. How E6AP recognizes its cellular targets and how its ubiquitin ligase activity is triggered remain poorly understood, and HPV E6 proteins are models for these processes. We examined diverse E6 proteins from human and non-human papillomaviruses and identified two different modes of interaction between E6 and E6AP. In Type I interactions, E6 can interact directly with the LXXLL peptide motif alone of E6AP (isolated from the rest of E6AP), and then recruit cellular substrates such as p53. In Type II interactions, E6 proteins require additional auxiliary regions of E6AP in either the amino terminus or in the carboxy-terminal HECT domain to interact with the LXXLL peptide motif of E6AP. A region of E6AP amino-terminal to the LXXLL peptide motif both augments association with E6 proteins and is required for E6 proteins to trigger ubiquitin ligase activity in the carboxy-terminal HECT ubiquitin ligase domain of E6AP. In Type I interactions, E6 can associate with E6AP and recruit p53, but a Type II interaction is required for the degradation of p53 or NHERF1. Interestingly, different E6 proteins varied in E6AP auxiliary regions that contributed to enhanced association, indicating evolutionary drift in the formation of Type II interactions. This classification of E6-E6AP interaction types and identification of a region in the E6AP amino terminus that is important for both E6 association and stimulation of ubiquitin ligase activity will inform future structural data of the E6-E6AP complex and future studies aiming to interfere with the activity of the E6-E6AP complex.