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Nasopharyngeal carcinoma (NPC) is very common in southern China and Southeast Asia. In regions where NPC is endemic, undifferentiated subtypes constitute most cases and are invariably associated with Epstein-Barr virus (EBV) infection, whereas the differentiated subtype is more common in other parts of the world. Undifferentiated NPC is a unique malignancy with regard to its epidemiology, etiology, and clinical presentation. Clinically, NPC is highly invasive and metastatic, but sensitive to both chemotherapy and radiotherapy (RT). Overall prognosis has dramatically improved over the past three decades because of advances in management, including the improvement of RT technology, the broader application of chemotherapy, and more accurate disease staging. Despite the excellent local control with modern RT, distant failure remains a challenging problem. Advances in molecular technology have helped to elucidate the molecular pathogenesis of NPC. This article reviews the contribution of EBV gene products to NPC pathogenesis and the current management of NPC.

Latent membrane protein 1 (LMP1) is a primary oncogene encoded by the Epstein‐Barr virus, and various portions of LMP1 are detected in nasopharyngeal carcinoma (NPC) tumor cells. LMP1 has been extensively studied since the discovery of its transforming property in 1985. LMP1 promotes cancer cell growth during NPC development and facilitates the interaction of cancer cells with surrounding stromal cells for invasion, angiogenesis, and immune modulation. LMP1 is detected in 100% of pre‐invasive NPC tumors and in approximately 50% of advanced NPC tumors. Moreover, a small population of LMP1‐expressing cells in advanced NPC tumor tissue is proposed to orchestrate NPC tumor tissue maintenance and development through cancer stem cells and progenitor cells. Recent studies suggest that LMP1 activity shifts according to tumor development stage, but it still has a pivotal role during all stages of NPC development. Epstein‐Barr virus LMP1 is a primary oncogene that transform various mammalian cells. LMP1 also modulates nasopharyngeal carcinoma microenvironment and contributes NPC development.

Cancer cells show a dynamic metabolic landscape, requiring a sufficient supply of nucleotides to proliferate. They are highly dependent on de novo purine biosynthetic pathways for their nucleotide requirements. Phosphoribosyl pyrophosphate amidotransferase (PPAT), catalyzing the first step of de novo purine biosynthesis, is highly expressed in various cancers. We observed an increased expression of PPAT in nasopharyngeal carcinoma (NPC). Moreover, our ribonucleic acid sequencing analysis showed high PPAT expression in Epstein–Barr virus‐positive NPC, which was supported by in vitro analysis. Through a gene knockdown study, we showed that the suppression of PPAT expression reduced the proliferation and invasion of NPC cells. We also demonstrated the regulation of PPAT by glutamine, a cosubstrate for PPAT. A glutamine antagonist, 6‐diazo‐5‐oxo‐L‐norleucine, blocked glutamine‐mediated induction of PPAT and reduced NPC cell proliferation. Immunohistochemical analysis of PPAT in NPC tissues revealed increased expression of PPAT with disease progression, which was significantly associated with poor prognosis. In summary, this study highlighted the biological function of PPAT in NPC, establishing its potential as a novel prognostic biomarker for aggressive NPC and a promising therapeutic target. We investigated the role of phosphoribosyl pyrophosphate amidotransferase (PPAT) in nasopharyngeal carcinoma (NPC), revealing heightened PPAT expression in Epstein–Barr virus‐positive NPC. The research establishes PPAT as a crucial factor influencing NPC cell proliferation and invasion, with glutamine identified as a key regulator; the study suggests PPAT as a potential prognostic biomarker and therapeutic target for aggressive NPC.

Cancer immune responses are generated in secondary lymphoid organs, such as the lymph nodes and tonsils. In the current study, transcriptional profiles of peritumoral tonsillar tissues (PTTs) from oropharyngeal cancers (OPCs) were assessed and compared with those of inflammatory tonsils and regional lymph nodes (rLNs). RNA samples of PTTs and rLNs from 13 OPCs, and 4 inflammatory tonsils were subjected to microarray analysis, and differentially expressed genes (DEGs) identified from 730 nCounter Panel immune-related genes. Gene Set enrichment Analysis (GSEA) was used for DEG profiling of PTTs and rLNs between lymph node metastasis-negative and metastasis-positive cases. The top 20 genes, as ranked by GSEA metric scores, were extracted and subjected to principal component analysis (PCA). The correlation of each patient's PCA score with lymph node status was assessed by Receiver Operating Characteristics (ROC) analysis. Comparing DEG analyses of PTTs with those of inflammatory tonsils and rLNs revealed 144 and 45 upregulated genes, respectively. ClueGO, a widely used Cytoscape plug-in, revealed activated pathways in PTTs, including lymphocyte proliferation (followed by T cell activation involved in the immune response) and positive regulation of leukocyte migration (followed by antimicrobial humoral immune response mediated by antimicrobial peptides) as the most significantly enriched immune system process functions in the gene ontology when comparing inflammatory tonsils and rLNs. The area under the ROC curves of PTTs and rLNs were 0.806 and 0.389, and were significant by DeLong's test (p = 0.025). PTTs exhibit unique immunological features distinguishing them from inflammatory tonsils and rLNs. Gene expression analysis of PTTs is useful for investigating the mechanism of OPC lymphatic spread, even compared with analysis of rLNs.

Several epidemiological studies have suggested that Epstein–Barr virus (EBV) lytic infection is essential for the development of nasopharyngeal carcinoma (NPC), as the elevation of antibody titers against EBV lytic proteins is a common feature of NPC. Although ZEBRA protein is a key trigger for the initiation of lytic infection, whether its expression affects the prognosis and pathogenesis of NPC remains unclear. In this study, 64 NPC biopsy specimens were analyzed using immunohistochemistry. We found that ZEBRA was significantly associated with a worsening of progression‐free survival in NPC (adjusted hazard ratio, 3.58; 95% confidence interval, 1.08–11.87; p = 0.037). Moreover, ZEBRA expression positively correlated with key endocrinological proteins, estrogen receptor α, and aromatase. The transcriptional level of ZEBRA is activated by estrogen in an estrogen receptor α‐dependent manner, resulting in an increase in structural gene expression levels and extracellular virus DNA copy number in NPC cell lines, reminiscent of lytic infection. Interestingly, it did not suppress cellular proliferation or increase apoptosis, in contrast with cells treated with 12‐O‐tetradecanoylphorbol‐13‐acetate and sodium butyrate, indicating that viral production induced by estrogen is not a cell lytic phenomenon. Our results suggest that intratumoral estrogen overproduced by aromatase could induce ZEBRA expression and EBV reactivation, contributing to the progression of NPC. We have revealed that EBV lytic protein ZEBRA is significantly associated with poor prognosis of nasopharyngeal carcinoma. Moreover, our study suggests that locally expressed intratumoral estrogen induces EBV lytic protein ZEBRA expression from the gene expression level. We expect of the development of novel treatment modalities such as anti‐hormonal treatment.

Nasopharyngeal carcinoma (NPC) is caused by infection with Epstein–Barr virus (EBV) and endemic in certain geographic regions. EBV lytic gene, BALF2, closely associates with viral reactivation and BALF2 gene variation, the H‐H‐H strain, causes NPC in endemic region, southern China. Here, we investigate whether such EBV variations also affect NPC in a non‐endemic region, Japan. Viral genome sequencing with 47 EBV isolates of Japanese NPC were performed and compared with those of other EBV‐associated diseases from Japan or NPC in Southern China. EBV genomes of Japanese NPC are different from those of other diseases in Japan or endemic NPC; Japanese NPC was not affected by the endemic strain (the BALF2 H‐H‐H) but frequently carried the type 2 EBV or the strain with intermediate risk of endemic NPC (the BALF2 H‐H‐L). Seven single nucleotide variations were specifically associated with Japanese NPC, of which six were present in both type 1 and 2 EBV genomes, suggesting the contribution of the type 2 EBV‐derived haplotype. This observation was supported by a higher viral titer and stronger viral reactivation in NPC with either type 2 or H‐H‐L strains. Our results highlight the importance of viral strains and viral reactivation in the pathogenesis of non‐endemic NPC. Epstein–Barr virus (EBV) genome variation such as BALF2 that is associated with viral reactivation is a risk factor of nasopharyngeal carcinoma (NPC) in endemic regions such as southern China. We found unique BALF2 genome variation in EBV isolates of NPC in Japan, an non‐endemic region, different from endemic NPC. We revealed the importance of viral strains and their reactivation in the pathogenesis of non‐endemic NPC.

Alport syndrome (AS) is a genetic disorder characterized by progressive nephritis, hearing loss, and visual impairment. Quantitative analyses of hearing in AS are rare. We conducted a retrospective chart review of clinical features and longitudinal follow-up of patients with AS, including multiple evaluations of pure-tone audiograms in each individual and examination of the relationships between hearing loss and genetic variants. Twelve AS cases from eight Japanese families were studied: one family had an autosomal dominant COL4A4 variant and seven carried X-linked variants in COL4A5 ; all cases presented with moderate hearing loss. Progression of hearing loss was 0.25, 0.29, 0.57, and 2.60 dB HL/year at 500, 1000, 4000, and 8000 Hz, respectively. During follow-up (1–10 years), all families exhibited mid-frequency hearing loss. Hearing loss onset occurred later than renal symptoms in all patients with COL4A5 variants, and the COL4A4 variant did not cause renal symptoms. Hearing loss severity and age of onset appeared to vary depending on the characteristics of the genetic variants, indicating genotype–phenotype correlations; however, hearing decline was predominantly at high frequencies, regardless of genetic variation. These findings provide valuable insights into genotype–phenotype correlations in AS, particularly regarding hearing loss progression and characteristics.

Cisplatin (CDDP) has been a key drug for chemotherapy in patients with head and neck squamous cell carcinoma. Nephrotoxicity is one of its adverse reactions that are dose limiting. To increase its antitumor effects and reduce such toxicity problems, polymeric micelles carrying CDDP (NC‐6004) have been developed. The present study was designed to evaluate the efficacy and safety of NC‐6004 for oral squamous cell carcinoma. In vitro antitumor activity was assayed in four oral squamous cell carcinoma cell lines. To investigate the antitumor and nephrotoxic effects of NC‐6004, nude mice bearing OSC‐19 were administered NC‐6004 or CDDP. The in vitro growth‐inhibitory effect of NC‐6004 was significantly less than that of CDDP. However, both NC‐6004 and CDDP showed equivalent antitumor effects in vivo. Mice with CDDP developed renal cell apoptosis; however, those injected with NC‐6004 were almost free of renal cell injury. Moreover, in an orthotopic tongue cancer model using OSC‐19, NC‐6004 reduced the rate of sentinel lymph node metastasis to lower than that with CDDP. In conclusion, considering the potential advantages in terms of noticeable antitumor activity, lymphatic drug delivery and reduced nephrotoxicity, NC‐6004 represents a significant structural improvement in the development of a platinum complex.

Cancer immune responses are generated in secondary lymphoid organs, such as the lymph nodes and tonsils. In the current study, transcriptional profiles of peritumoral tonsillar tissues (PTTs) from oropharyngeal cancers (OPCs) were assessed and compared with those of inflammatory tonsils and regional lymph nodes (rLNs). RNA samples of PTTs and rLNs from 13 OPCs, and 4 inflammatory tonsils were subjected to microarray analysis, and differentially expressed genes (DEGs) identified from 730 nCounter Panel immune-related genes. Gene Set enrichment Analysis (GSEA) was used for DEG profiling of PTTs and rLNs between lymph node metastasis-negative and metastasis-positive cases. The top 20 genes, as ranked by GSEA metric scores, were extracted and subjected to principal component analysis (PCA). The correlation of each patient's PCA score with lymph node status was assessed by Receiver Operating Characteristics (ROC) analysis. Comparing DEG analyses of PTTs with those of inflammatory tonsils and rLNs revealed 144 and 45 upregulated genes, respectively. ClueGO, a widely used Cytoscape plug-in, revealed activated pathways in PTTs, including lymphocyte proliferation (followed by T cell activation involved in the immune response) and positive regulation of leukocyte migration (followed by antimicrobial humoral immune response mediated by antimicrobial peptides) as the most significantly enriched immune system process functions in the gene ontology when comparing inflammatory tonsils and rLNs. The area under the ROC curves of PTTs and rLNs were 0.806 and 0.389, and were significant by DeLong's test (p = 0.025). PTTs exhibit unique immunological features distinguishing them from inflammatory tonsils and rLNs. Gene expression analysis of PTTs is useful for investigating the mechanism of OPC lymphatic spread, even compared with analysis of rLNs.

Human papillomavirus (HPV) is a known risk factor for oropharyngeal cancer (OPC), with distinct HPV-positive and HPV-negative subtypes. Reactive oxygen species have been implicated in the carcinogenesis of several malignancies. Superoxide dismutase 2 (SOD2), a mitochondrial enzyme, is highly influenced by oxidative stress. This study investigated whether SOD1 and SOD2 expression in OPC affects primary tumor progression, lymph node metastasis, stage, and overall survival (OS). Biopsy or surgically resected specimens from 72 patients with OPC were analyzed via immunohistochemical staining for SOD1 and SOD2. The proportion of stained cells within the tumor area was assessed. Associations between SOD1 and SOD2 expression, T classification, N classification, and stage were evaluated. Factors correlated with OS in OPC were also examined. No significant differences in SOD1 or SOD2 expression were observed concerning T or N classification, or stage. However, high SOD2 expression was identified as a significant poor prognostic factor for OS. Regardless of HPV status, SOD2 expression predicts poor prognosis in OPC. Evaluating SOD2 expression may help predict OPC prognosis.