The ubiquitin specific protease 7 stabilizes HPV16E7 to promote HPV-mediated carcinogenesis.

Human papillomavirus (HPV) encoded E7 oncoprotein plays an important role in supporting the viral productive cycle and inducing cancer phenotypes. The ability of E7 to exercise these functions, partly, depends upon its steady-state level. HPV manipulates the host de-ubiquitination pathway to maintain the stability of its viral proteins. In this study, we uncovered that HPV interacts with the host ubiquitin specific protease 7 (USP7), a universal de-ubiquitinating enzyme, leading to the stabilization of E7 oncoprotein. We observed that HPV16E7 complexes with USP7 via the E7-CR3 domain, and this E7-USP7 complex exists predominantly in the nucleus. Our results showed that USP7 stabilizes and prolongs the half-life of HPV16E7 by antagonizing ubiquitination and proteasomal degradation. Consistently, when we inhibited USP7 activity using HBX 19818, HPV16E7 protein level was reduced and its turnover was increased. We also provide evidence that HBX 19818-induced USP7 inhibition can halt HPV-mediated carcinogenesis, including cell proliferation, invasion, migration and transformation. These findings indicate that USP7 plays an essential role in stabilizing E7. The specific and potent inhibitory effects of HBX 19818 on HPV-induced carcinogenesis provide a molecular insight, suggesting the potential of targeting USP7 as a new therapeutic approach for the treatment of HPV-associated cancers.

Human Papillomavirus 58 E7 T20I/G63S Variant Isolated from an East Asian Population Possesses High Oncogenicity.

Human papillomavirus (HPV) type 58 is the third most commonly detected HPV type in cervical cancer among Eastern Asians. Our previous international epidemiological studies revealed that HPV58 carrying an E7 natural variant, T20I/G63S (designated V1), was associated with a higher risk of cervical cancer. We recently showed that V1 possesses a greater ability to immortalize and transform primary cells, as well as degrading pRB more effectively, than the prototype and other common variants. In this study, we performed a series of phenotypic and molecular assays using physiologically relevant in vitro and in vivo models to compare the oncogenicity of V1 with that of the prototype and other common natural variants. Through activation of the AKT and K-Ras/extracellular signal-regulated kinase (ERK) signaling pathways, V1 consistently showed greater oncogenicity than the prototype and other variants, as demonstrated by increased cell proliferation, migration, and invasion, as well as induction of larger tumors in athymic nude mice. This study complements our previous epidemiological and molecular observations pinpointing the higher oncogenicity of V1 than that of the prototype and all other common variants. Since V1 is more commonly found in eastern Asia, our report provides insight into the design of HPV screening assays and selection of components for HPV vaccines in this region.IMPORTANCE Epidemiological studies have revealed that a wild-type variant of HPV58 carrying an E7 variation, T20I/G63S (V1), is associated with a higher risk of cervical cancer. We previously reported that this increased oncogenicity could be the result of the virus's greater ability to degrade pRB, thereby leading to an increased ability to grow in an anchorage-independent manner. In addition to this, this report further showed that this HPV variant induced activation of the AKT and K-Ras/ERK signaling pathways, thereby explaining its genuine oncogenicity in promoting cell proliferation, migration, invasion, and formation of tumors, all to a greater extent than the prototype HPV58 and other common variants.

A chicken liver cell line efficiently supports the replication of ALV-J possibly through its high level viral receptor and efficient protein expression system.

In this study, we identified a chicken liver cell line (LMH) which could strongly support the replication of ALV-J (Subgroup J of avian leukosis virus) with high viral titer. Notably, ALV-J was efficiently detected by ELISA in LMH cells 1 day before DF1 cells. In comparison with DF1 cells, LMH cells not only expressed higher levels of ALV-J receptor chNHE-1, but also possessed a more efficient protein expression system for foreign genes. Thus, LMH cells could be a novel tool to shorten the ALV-J eradication approach and accelerate studies on the pathogenesis and oncogenesis of ALV-J.

Changes in the Incidence and Human Papillomavirus-Positive Portion of Oropharyngeal Squamous Cell Carcinoma in Hong Kong.

The incidence of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is rising in the West, but little is known in Asia. This study elucidated changes in the incidence and HPV-positive portion of OPSCC in Hong Kong. Data from population-based cancer registry were used to analyze the incidence of OPSCC in association with other head and neck cancers. Archived tumor tissues were tested for HPV. From 1986 to 2020, there was a marked decrease in the incidence of nasopharyngeal and laryngeal cancers, but a persistent increase in OPSCC from 36 cases in 1986 to 116 cases in 2020. The average positive rate for high-risk HPV was 36.1% (112/310) among OPSCC diagnosed in 2010-2020. The HPV-positive rate in recent years was significantly higher than earlier cases (tonsil SCC: 64.7% (55/85) in 2016-2020 vs. 40.4% (19/47) in 2010-2015, p = 0.007). Patients with HPV-positive tonsil cancers were significantly younger than those negative (mean [SD]: 58.9 [9.9] vs. 64.3 [13.3] years, p = 0.006), but no significant difference was observed between genders. A persistent increase in the incidence of oropharyngeal cancer over the last few decades was observed in Hong Kong, which can be explained by the remarkable increase in HPV-positive tonsil cancers.

Oesophageal carcinoma: The prevalence of DNA tumour viruses and therapy.

Oesophageal carcinoma ranks the sixth leading cause of cancer death and affected 544,000 - 604,000 people in 2020. Patients often presented with a poor cancer prognosis with a low survival rate of 15-25%. Depending upon the cell type, oesophageal carcinoma is categorised into oesophageal squamous cell carcinoma (ESCC) and oesophageal adenocarcinoma (EAC). ESCC is predominantly reported in developing countries, while EAC is more common in developed countries. Aside from the presence of exogenous co-factors, such as cigarette smoking, alcohol consumption, obesity, gastroesophageal reflux disease (GERD); infection with oncogenic viruses is suspected to be one of the major factors contributing to EC development. Oncogenic viruses, including human papillomavirus (HPV), Epstein Barr virus (EBV), Cytomegalovirus (CMV) and Herpes Simplex Virus (HSV) have been detected in various proportions of EC samples. Nonetheless, their aetiological roles in EC remain debatable. In this review, we garnered previous studies that focus on the association between oncogenic viruses and EC. Among these oncogenic viruses, HPV appears to have a stronger association with EC than the others. In addition, we also discuss the pros and cons of the treatment regimens to treat EC patients, including immunotherapy, chemo- and chemoradiotherapy, and their efficacy.

Current Updates on Cancer-Causing Types of Human Papillomaviruses (HPVs) in East, Southeast, and South Asia.

Human papillomavirus (HPV) infection remains one of the most prominent cancer-causing DNA viruses, contributing to approximately 5% of human cancers. While association between HPV and cervical cancers has been well-established, evidence on the attribution of head and neck cancers (HNC) to HPV have been increasing in recent years. Among the cancer-causing HPV genotypes, HPV16 and 18 remain the major contributors to cancers across the globe. Nonetheless, the distribution of HPV genotypes in ethnically, geographically, and socio-economically diverse East, Southeast, and South Asia may differ from other parts of the world. In this review, we garner and provide updated insight into various aspects of HPV reported in recent years (2015-2021) in these regions. We included: (i) the HPV genotypes detected in normal cancers of the uterine cervix and head and neck, as well as the distribution of the HPV genotypes by geography and age groups; (ii) the laboratory diagnostic methods and treatment regimens used within these regions; and (iii) the oncogenic properties of HPV prototypes and their variants contributing to carcinogenesis. More importantly, we also unveil the similarities and discrepancies between these aspects, the areas lacking study, and the challenges faced in HPV studies.

Temporal-Geographical Dispersion of SARS-CoV-2 Spike Glycoprotein Variant Lineages and Their Functional Prediction Using in Silico Approach.

SARS-CoV-2 is a positive-sense single-stranded RNA virus with emerging mutations, especially on the Spike glycoprotein (S protein). To delineate the genomic diversity in association with geographic dispersion of SARS-CoV-2 variant lineages, we collected 939,591 complete S protein sequences deposited in the Global Initiative on Sharing All Influenza Data (GISAID) from December 2019 to April 2021. An exponential emergence of S protein variants was observed since October 2020 when the four major variants of concern (VOCs), namely, alpha (α) (B.1.1.7), beta (ß) (B.1.351), gamma (γ) (P.1), and delta (δ) (B.1.617), started to circulate in various communities. We found that residues 452, 477, 484, and 501, the 4 key amino acids located in the hACE2 binding domain of S protein, were under positive selection. Through in silico protein structure prediction and immunoinformatics tools, we discovered D614G is the key determinant to S protein conformational change, while variations of N439K, T478I, E484K, and N501Y in S1-RBD also had an impact on S protein binding affinity to hACE2 and antigenicity. Finally, we predicted that the yet-to-be-identified hypothetical N439S, T478S, and N501K mutations could confer an even greater binding affinity to hACE2 and evade host immune surveillance more efficiently than the respective native variants. This study documented the evolution of SARS-CoV-2 S protein over the first 16 months of the pandemic and identified several key amino acid changes that are predicted to confer a substantial impact on transmission and immunological recognition. These findings convey crucial information to sequence-based surveillance programs and the design of next-generation vaccines. IMPORTANCE Our study showed the global distribution of SARS-CoV-2 S protein variants from January 2020 to the end of April 2021. We highlighted the key amino acids of S protein subjected to positive selection. Using computer-aided approaches, we predicted the impact of the amino acid variations in S protein on viral infectivity and antigenicity. We also predicted the potential amino acid mutations that could arise in favor of SARS-CoV-2 virulence. These findings are vital for vaccine designing and anti-SARS-CoV-2 drug discovery in an effort to combat COVID-19.