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Background: 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). Methods: 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. Results: 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). Conclusion: 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. [ABSTRACT FROM AUTHOR]

The electromotility of outer hair cell is considered to be based on voltage-dependent conformational changes in the motor protein prestin. The structure and function of prestin have been increasingly examined in recent years. To obtain further information on prestin, a method to stably obtain prestin as the material for this research is required. This study attempted to construct a stable expression system for prestin on Chinese hamster ovary (CHO) cells and its function was evaluated. His-tagged prestin expression vectors were transfected into CHO cells and high-expression clones were obtained by drug selection and limiting dilution method. The expression and activity of prestin were examined by Western blotting and immunofluorescent experiments and by patch clamping. Clones with high fluorescent intensity tended to exhibit bell-shaped non-linear capacitance, suggesting the active function of prestin in such clones. The stable expression and activity of prestin in CHO cells were confirmed in 7 clones out of twelve clones developed. Although expression levels were 1/60-1/30 of those in OHCs, cell line maintaining the stable expression of functional prestin with His tag will be advantageous for future analyses of its structure and function. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Epstein‐Barr virus (EBV)‐associated nasopharyngeal carcinoma (NPC) cells have high metastatic potential. Recent research has revealed that the interaction of between tumor cells and the surrounding stroma plays an important role in tumor invasion and metastasis. In this study, we showed the prognostic value of expression of SPARC, an extracellular matrix protein with multiple cellular functions, in normal adjacent tissues (NAT) surrounding NPC. In the immunohistochemical analysis of 51 NPC biopsy specimens, SPARC expression levels were significantly elevated in the NAT of EBER (EBV‐encoded small RNA)‐positive NPC compared to that in the NAT of EBER‐negative NPC. Moreover, increased SPARC expression in NAT was associated with a worsening of overall survival. The enrichment analysis of RNA‐seq of publicly available NPC and NAT surrounding NPC data showed that high SPARC expression in NPC was associated with epithelial mesenchymal transition promotion, and there was a dynamic change in the gene expression profile associated with interference of cellular proliferation in NAT, including SPARC expression. Furthermore, EBV‐positive NPC cells induce SPARC expression in normal nasopharyngeal cells via exosomes. Induction of SPARC in cancer‐surrounding NAT cells reduced intercellular adhesion in normal nasopharyngeal structures and promoted cell competition between cancer cells and normal epithelial cells. These results suggest that epithelial cells loosen their own binding with the extracellular matrix as well as stromal cells, facilitating the invasion of tumor cells into the adjacent stroma by activating cell competition. Our findings reveal a new mechanism by which EBV creates a pro‐metastatic microenvironment by upregulating SPARC expression in NPC. [ABSTRACT FROM AUTHOR]