Human papillomaviruses (HPVs) represent a diverse group of DNA viruses that infect epithelial cells of mucosal and cutaneous tissues, leading to a wide spectrum of clinical outcomes. Among various ...HPVs, alpha (α) and beta (β) types have garnered significant attention due to their associations with human health. α-HPVs are primarily linked to infections of the mucosa, with high-risk subtypes, such as HPV16 and HPV18, being the major etiological agents of cervical and oropharyngeal cancers. In contrast, β-HPVs are predominantly associated with cutaneous infections and are commonly found on healthy skin. However, certain β-types, notably HPV5 and HPV8, have been implicated in the development of non-melanoma skin cancers in immunocompromised individuals, highlighting their potential role in pathogenicity. In this review, we comprehensively analyze the similarities and differences between α- and β-HPV E6 oncoproteins, one of the major drivers of viral replication and cellular transformation, and how these impact viral fitness and the capacity to induce malignancy. In particular, we compare the mechanisms these oncoproteins use to modulate common cellular processes-apoptosis, DNA damage repair, cell differentiation, and the immune response-further shedding light on their shared and distinct features, which enable them to replicate at divergent locations of the human body and cause different types of cancer.
Human papillomaviruses (HPVs), which are small, double-stranded, circular DNA viruses infecting human epithelial cells, are associated with various benign and malignant lesions of mucosa and skin. ...Intensive research on the oncogenic potential of HPVs started in the 1970s and spread across Europe, including Croatia, and worldwide. Nowadays, the causative role of a subset of oncogenic or high-risk (HR) HPV types, led by HPV-16 and HPV-18, of different anogenital and head and neck cancers is well accepted. Two major viral oncoproteins, E6 and E7, are directly involved in the development of HPV-related malignancies by targeting synergistically various cellular pathways involved in the regulation of cell cycle control, apoptosis, and cell polarity control networks as well as host immune response. This review is aimed at describing the key elements in HPV-related carcinogenesis and the advances in cancer prevention with reference to past and on-going research in Croatia.
Human papillomaviruses (HPVs) infect the dividing cells of human epithelia and hijack the cellular replication machinery to ensure their own propagation. In the effort to adapt the cell to suit their ...own reproductive needs, the virus changes a number of processes, amongst which is the ability of the cell to undergo programmed cell death. Viral infections, forced cell divisions and mutations, which accumulate as a result of uncontrolled proliferation, all trigger one of several cell death pathways. Here, we examine the mechanisms employed by HPVs to ensure the survival of infected cells manipulated into cell cycle progression and proliferation.
Infection with human papillomaviruses (HPVs), in particular with HPV type 16, is now considered to be a key risk factor for the development of a subset of oropharyngeal squamous cell carcinomas ...(OPSCC) that show different epidemiological, clinical, and prognostic characteristics from HPV-negative (HPV−) OPSCCs. So far, extensive research efforts aiming to distinguish these two distinct entities have not identified specific biomarkers, nor led to different therapies. Previous research has shown that HPV16 E6 oncoprotein binds NHERF2, inducing its proteasomal degradation, and consequently increasing cell proliferation; we therefore aimed to investigate how this might be reflected in human histological samples. We analyzed NHERF2 expression patterns in HPV16-positive (HPV16+) and HPV− OPSCC samples, to investigate any potential differences in NHERF2 pattern. Interestingly, we observed a statistically significant decrease in NHERF2 levels in HPV16+ and poorly differentiated HPV− OPSCCs, compared with healthy tissue. Furthermore, we observed a significant reduction in the percentage of NHERF2 immunoreactive cancer cells in HPV16+ tumors, compared with well and moderately differentiated HPV− OPSCCs, suggesting the importance of 16E6’s targeting of NHERF2 in HPV-driven oncogenesis in the head and neck area.
Human papillomavirus (HPV) E6 and E7 oncoproteins are critical for development and maintenance of the malignant phenotype in HPV-induced cancers. These two viral oncoproteins interfere with a ...plethora of cellular pathways, including the regulation of cell cycle and the control of apoptosis, which are critical in maintaining normal cellular functions. E6 and E7 bind directly with certain components of the Ubiquitin Proteasome System (UPS), enabling them to manipulate a number of important cellular pathways. These activities are the means by which HPV establishes an environment supporting the normal viral life cycle, however in some instances they can also lead to the development of malignancy. In this review, we have discussed how E6 and E7 oncoproteins from alpha and beta HPV types interact with the components of the UPS, and how this interplay contributes to the development of cancer.
Background The Notch pathway combined with other signalling molecules acts specifically for the development of each blood cell type and differentiation stage. A causative role of Notch dysfunction in ...leukaemia development has been found in many studies so, initially only for T- acute lymphoblastic leukaemia (T-ALL) but more recently also for B cell and myeloid leukaemia. The aim of our study is to introduce a method for multiple direct analysis of the Notch pathway partners in a population of only 500 or fewer cells. The notion of this method consists in gaining insight into gene expression at the level of the malignant clone population. A small number of cells is a significant limitation when working on primary cells either when freshly isolated or when analysed after several days in cocultures. Methods The primers were designed to avoid genomic amplification through the selection of 3′ and 5′ primers that hybridise with different exons. Cell lines and primary cells were collected and multiplex quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) performed on a descending number of cells, ranging from 2,500 cells up to 50 cells per sample, for the Notch pathway genes and other transcription factors important for cell differentiation. ImageJ program, STATISTICA 13.1 software package and Student’s t-test were used for statistical evaluation. We checked protein expression by western blot. Results We characterised the gene expression levels of Notch, Ikaros and Parp genes in leukaemia cell lines of B and T origin and in primary leukaemia samples of limited size. We further compared our results to the cDNA analysis obtained by total RNA isolation from a large number of cells as routinely performed in clinical laboratories, and finally tested the method described on primary cells from leukaemia patients. Conclusions This rapid multiple gene expression analysis of a small population of cells provides efficient cell classification determining malignant changes as an important additional information for clinical leukaemia diagnostics as well as for in vitro studies of primary cells.
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.
While a small proportion of high‐risk (HR) alpha (α) human papillomaviruses (HPVs) is associated with numerous human malignancies, of which cervical cancer is the most prevalent, beta (β) HPVs ...predominantly act as co‐factors in skin carcinogenesis. A characteristic feature of both α‐ and β‐E6 oncoproteins is the presence of the LXXLL binding motif, which α‐E6s utilize to form a complex with E6AP and which enables β‐E6s to interact with MAML1. Here we show that multiple α‐E6 oncoproteins bind to MAML1 via the LXXLL binding motif and that this results in increased protein stability. Moreover, β‐E6 oncoprotein stability is also dependent on the interaction with MAML1. Additionally, in the absence of MAML1, endogenous HPV‐8 E6 and HPV‐18 E6 are rapidly degraded at the proteasome. Ablation of both E6AP and MAML1 leads to an even more profound downregulation of α‐E6 protein expression, whereas this is not observed with β‐E6. This highly suggests that there is one cellular pool for most of β‐E6 that interacts solely with MAML1, whereas there are two cellular pools of HR α‐E6, one forming a complex with MAML1 and the other interacting with E6AP. Furthermore, MAML1 induces HPV‐8 E6 shuttling from the nucleus to the cytosolic fraction, while MAML1 interaction with HR E6 induces a drastic nuclear and membrane upregulation of E6. Interestingly, the HR α‐E6/MAML1 complex does not affect targeting of some of the known HR E6 cellular substrates such as p53 and DLG1. However, MAML1 and E6AP joint co‐expression with HR α‐E6 leads to a significant increase in cellular proliferation, whereas silencing MAML1 decreases wound closure in HeLa cells. These results demonstrate that HR α‐E6 interaction with MAML1 results in a stable form of E6, which likely modulates MAML1's normal cellular activities, one consequence of which being an increased proliferative capacity of HPV‐transformed cancer cells. Thus, this study shows a novel function of the α‐E6 oncoprotein and how it's activity might affect HPV‐induced pathogenesis.
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