Comprehensive Transcriptome Analysis Reveals the Distinct Gene Expression Patterns of Tumor Microenvironment in HPV-Associated and HPV-Non Associated Tonsillar Squamous Cell Carcinoma
Authors: Alahmadi Reham M. , Marraiki Najat , Alswayyed Mohammed , Khoja Hatim A. , Al-Anazi Abdullah E. , Alahmadi Rawan M. , Alkusayer Meshael M. , Alosaimi Bandar , Awadalla Maaweya 
Published: November 2023

Head and neck squamous cell carcinomas (HNSCCs) are a common type of cancer, ranking as the sixth most prevalent cancer worldwide and having a high morbidity and mortality rate. Among oropharyngeal squamous cell carcinoma (OPSCC) cancers, tonsillar squamous cell carcinoma (TSCC) is the most prevalent and has a particularly aggressive clinical course with poor disease outcomes. The tumor microenvironment (TME) of HNSCC is complex and heterogeneous, playing a crucial role in effective cancer therapy. Understanding the interaction between cancer inflammation, immunity, oncogenes, and tumor suppressor genes is essential for developing effective cancer treatments. This study aimed to gain a comprehensive understanding of the transcriptomes of the TME in TSCC, both associated with human papillomavirus (HPV) and not associated with HPV. The gene expression profiles of 168 genes linked to various cellular mediators and factors involved in inflammation, immunity crosstalk, transcription, signal transduction, oncogenesis, tumor suppression, angiogenesis, and apoptosis were analyzed. We identified 40 differentially expressed genes related to the communication between tumor cells and the cellular mediators of inflammation and immunity crosstalk. In HPV-positive TSCC patients, 33 genes were over-expressed with a fold change greater than 1.5, and 26 of these genes were unique to this group. In contrast, HPV-negative TSCC patients had 11 up-regulated genes. The results further showed that 48 gene transcripts related to oncogenesis, tumor suppression, angiogenesis, and apoptosis were up-regulated in both HPV-positive and HPV-negative TSCC patients. Among the HPV-positive TSCC patients, 37 genes were over-expressed, while the HPV-negative TSCC patients had 11 up-regulated genes. The tumor microenvironment (TME) of HPV-associated and HPV-non-associated TSCC exhibited distinct characteristics, including the dysregulation of various genes involved in cellular mediators, inflammation, immunity crosstalk, transcription factors, immune signaling pathways, signal transduction, oncogenesis, tumor suppression, angiogenesis, and apoptosis. Additionally, we detected six Hr-HPV genotypes in 81% of the TSCC patients, with HPV-16 and HPV-35 being the most common types, followed by HPV-45 and HPV-18. HPV-39 and 31 were also identified. The presence of Hr-HPV genotypes in TSCC patients varied from single to multiple infections. In conclusion, we observed distinct heterogeneity in the transcriptome of the microenvironment in HPV-associated and non-associated TSCC. Further in vitro and in vivo studies are needed to investigate the functional implications of the identified over-expressed genes. Also, deeper molecular pathways and immunological studies on the TME are required to determine the potential of targeting genes for cancer therapy.