Functional characterization of alternatively spliced GSN in head and neck squamous cell carcinoma

Indisulam Shows an Anti-Cancer Effect on HPV+ and HPV- Head and Neck Cancer

Background/Objectives: HPV+ head and neck squamous cell carcinoma has been shown to have a unique genomic background, requiring researchers to study it as its own distinct type of cancer. HPV+ tumors have been shown to exhibit fewer genetic mutations in cancer drivers as opposed to their HPV- counterparts. In this paper, we explored how targeting post-transcriptional changes, specifically alternative splicing events, could serve as a potential mechanism to treat HPV+ cancer. Methods: Using indisulam, a drug that targets alternative splicing through the degradation of RBM39, we treated various HPV+ and HPV- cell lines and assessed tumor cell viability. We also tested indisulam in vivo to evaluate its effect on tumor volume. Additionally, we analyzed gene expression differences between indisulam-treated subjects and their non-treated counterparts. Results: Indisulam treatment led to a reduction in tumor cell viability in both HPV+ and HPV- cell lines. In vivo experiments showed a reduction in tumor volume following indisulam treatment. Gene expression analysis revealed that indisulam induces consistent differential gene expression changes and highly enriches interferon pathways in treated HPV+ cell lines. Conclusions: These findings suggest that targeting alternative splicing via indisulam may be a promising therapeutic approach for HPV+ cancers. Further research is required to establish indisulam as a viable anti-cancer treatment in clinical settings.

Identifying Strong Neoantigen MHC-I/II Binding Candidates for Targeted Immunotherapy with SINE

The discovery of tumor-derived neoantigens which elicit an immune response through major histocompatibility complex (MHC-I/II) binding has led to significant advancements in immunotherapy. While many neoantigens have been discovered through the identification of non-synonymous mutations, the rate of these is low in some cancers, including head and neck squamous cell carcinoma. Therefore, the identification of neoantigens through additional means, such as aberrant splicing, is necessary. To achieve this, we developed the splice isoform neoantigen evaluator (SINE) pipeline. Our tool documents peptides present on spliced or inserted genomic regions of interest using Patient Harmonic-mean Best Rank scores, calculating the MHC-I/II binding affinity across the complete human leukocyte antigen landscape. Here, we found 125 potentially immunogenic events and 9 principal binders in a cohort of head and neck cancer patients where the corresponding wild-type peptides display no MHC-I/II affinity. Further, in a melanoma cohort of patients treated with anti-PD1 therapy, the expression of immunogenic splicing events identified by SINE predicted response, potentially indicating the existence of immune editing in these tumors. Overall, we demonstrate SINE's ability to identify clinically relevant immunogenic neojunctions, thus acting as a useful tool for researchers seeking to understand the neoantigen landscape from aberrant splicing in cancer.

Alternative Splicing Landscape of Head and Neck Squamous Cell Carcinoma

Head and neck malignancies are a significant global health concern, with head and neck squamous cell carcinoma (HNSCC) being the sixth most common cancer worldwide accounting for > 90% of cases. In recent years, there has been growing recognition of the potential role of alternative splicing (AS) in the etiology of cancer. Increasing evidence suggests that AS is associated with various aspects of cancer progression, including tumor occurrence, invasion, metastasis, and drug resistance. Additionally, AS is involved in shaping the tumor microenvironment, which plays a crucial role in tumor development and response to therapy. AS can influence the expression of factors involved in angiogenesis, immune response, and extracellular matrix remodeling, all of which contribute to the formation of a supportive microenvironment for tumor growth. Exploring the mechanism of AS events in HNSCC could provide insights into the development and progression of this cancer, as well as its interaction with the tumor microenvironment. Understanding how AS contributes to the molecular changes in HNSCC cells and influences the tumor microenvironment could lead to the identification of new therapeutic targets. Targeted chemotherapy and immunotherapy strategies tailored to the specific AS patterns in HNSCC could potentially improve treatment outcomes and reduce side effects. This review explores the concept, types, processes, and technological advancements of AS, focusing on its role in the initiation, progression, treatment, and prognosis of HNSCC.

OutSplice: A Novel Tool for the Identification of Tumor-Specific Alternative Splicing Events

Protein variation that occurs during alternative splicing has been shown to play a major role in disease onset and oncogenesis. Due to this, we have developed OutSplice, a user-friendly algorithm to classify splicing outliers in tumor samples compared to a distribution of normal samples. Several tools have previously been developed to help uncover splicing events, each coming with varying methodologies, complexities, and features that can make it difficult for a new researcher to use or to determine which tool they should be using. Therefore, we benchmarked several algorithms to determine which may be best for a particular user's needs and demonstrate how OutSplice differs from these methodologies. We find that despite detecting a lower number of genes with significant aberrant events, OutSplice is able to identify those that are biologically impactful. Additionally, we identify 17 genes that contain significant splicing alterations in tumor tissue that were discovered across at least 5 of the tested algorithms, making them good candidates for future studies. Overall, researchers should consider a combined use of OutSplice with other splicing software to help provide additional validation for aberrant splicing events and to narrow down biologically relevant events.

Gelsolin Can Be a Prognostic Biomarker and Correlated with Immune Infiltrates in Gastric Cancer

BACKGROUND

Gelsolin (GSN) is the most widely expressed actin-severing protein in humans, which could regulate cell morphology, differentiation, movement and apoptosis. This study aims to explore the GSN as a prognostic biomarker of stomach adenocarcinoma (STAD).

METHODS

In this study, we used several online databases to comprehensively analyze the role of GSN in STAD. Oncomine and HPA databases were used to explore the GSN expression in various cancer, especially in gastric cancer. Then, UALCAN database was used to evaluate the relationship between GSN expression and promoter methylation in clinical characteristics. Finally, we used TIMER to analyze the correlation between GSN expression and immune infiltrates in gastric cancer.

RESULTS

GSN was down-regulated in gastric cancer, and decreased expression of GSN was related to worse survival. The GSN expression was significantly related to tumor purity in STAD and significantly correlated with infiltrating level of various immune cells, especially the dendritic cells.

CONCLUSION

Our study proposes that GSN can be served as the biomarker of disease and neoantigen for STAD treatment, which can improve the deficiency of disease-specific targeted therapies currently exist.

Development of alternative splicing signature in lung squamous cell carcinoma

Increasing evidence demonstrated that alternative splicing (AS) plays a vital role in tumorigenesis and clinical outcome of patient. However, systematical analysis of AS in lung squamous cell carcinoma (LUSC) is lacking and greatly necessary. Thus, this study was to systematically estimate the function of AS events served as prognostic indicators in LUSC. Among 31,345 mRNA AS events in 9633 genes, we detected 1996 AS in 1409 genes which have significant connection with overall survival (OS) of LUSC patients. Then, prognostic model based on seven types of AS events was established and we further constructed a combined prognostic model. The Kaplan–Meier curve results suggested that seven types of AS signatures and the combined prognostic model could exhibit robust performance in predicting prognosis. Patients in the high-risk group had significantly shorter OS than those in the low-risk group. The ROC showed all prognostic models had high accuracy and powerful predictive performance with different AUC ranging from 0.837 to 0.978. Moreover, the combined prognostic model had highest performance in risk stratification and predictive accuracy than single prognostic models and had higher accuracy than other mRNA model. Finally, a significant correlation network between survival-related AS genes and prognostic splicing factors (SFs) was established. In conclusion, our study provided several potential prognostic AS models and constructed splicing network between AS and SFs in LUSC, which could be used as potential indicators and treatment targets for LUSC patients.

The clinical significance of apolipoprotein L1 in head and neck squamous cell carcinoma

Approximately 500,000 new head and neck squamous cell carcinoma (HNSCC) cases are detected every year around the world, and its incidence ranks sixth among all cancer types globally. Among these cases, oral squamous cell carcinoma (OSCC) and laryngeal squamous cell carcinoma (LSCC) are HNSCC subtypes with high incidence rates, especially in China. The present study examines the association between the apolipoprotein L1 (APOL1) mRNA and protein expression and clinical parameters in HNSCC. The two most common types (oral and larynx) of HNSCC were selected for subgroup analyses. Immunohistochemistry (IHC) was used to detect APOL1 protein expression levels in HNSCC clinical specimens. It was demonstrated that APOL1 protein expression in 221 cases of HNSCC was higher compared with that in normal tissues. Consistent upregulation of APOL1 protein was also found in subgroups of OSCC and LSCC. Through mining the ArrayExpress, The Cancer Genome Atlas and the Gene Expression Omnibus databases, microarrays and RNA sequencing data for HNSCC were retrieved, which were used to analyze APOL1 mRNA expression levels. The results showed that APOL1 expression was higher in both OSCC and LSCC subtypes, as well as in HNSCC, compared with that in non-cancerous squamous epithelium. The summary receiver operating characteristic analysis showed that APOL1 had potential as a diagnostic biomarker for HNSCC, OSCC and LSCC. Thus, upregulation of APOL1 may contribute to the tumorigenesis of HNSCC.

Chromatin structure regulates cancer-specific alternative splicing events in primary HPV-related oropharyngeal squamous cell carcinoma

Human papillomavirus-related oropharyngeal squamous cell carcinoma (HPV+ OPSCC) represents a unique disease entity within head and neck cancer with rising incidence. Previous work has shown that alternative splicing events (ASEs) are prevalent in HPV+ OPSCC, but further validation is needed to understand the regulation of this process and its role in these tumours. In this study, eleven ASEs (GIT2, CTNNB1, MKNK2, MRPL33, SIPA1L3, SNHG6, SYCP2, TPRG1, ZHX2, ZNF331, and ELOVL1) were selected for validation from 109 previously published candidate ASEs to elucidate the post-transcriptional mechanisms of oncogenesis in HPV+ disease. In vitro qRT-PCR confirmed differential expression of 9 of 11 ASE candidates, and in silico analysis within the TCGA cohort confirmed 8 of 11 candidates. Six ASEs (MRPL33, SIPA1L3, SNHG6, TPRG1, ZHX2, and ELOVL1) showed significant differential expression across both methods. Further evaluation of chromatin modification revealed that ASEs strongly correlated with cancer-specific distribution of acetylated lysine 27 of histone 3 (H3K27ac). Subsequent epigenetic treatment of HPV+ HNSCC cell lines (UM-SCC-047 and UPCI-SCC-090) with JQ1 not only induced downregulation of cancer-specific ASE isoforms, but also growth inhibition in both cell lines. The UPCI-SCC-090 cell line, with greater ASE expression, also showed more significant growth inhibition after JQ1 treatment. This study confirms several novel cancer-specific ASEs in HPV+OPSCC and provides evidence for the role of chromatin modifications in regulation of alternative splicing in HPV+OPSCC. This highlights the role of epigenetic changes in the oncogenesis of HPV+OPSCC, which represents a unique, unexplored target for therapeutics that can alter the global post-transcriptional landscape.

Systemic Analysis of RNA Alternative Splicing Signals Related to the Prognosis for Head and Neck Squamous Cell Carcinoma

Alternative splicing (AS) is an important mechanism that is responsible for the production of protein diversity. An increasing body of evidence has suggested that out-of-control AS is closely related to the genesis and development of cancer. Systematic analysis of genome-wide AS in head and neck squamous cell carcinoma (HNSCC) has not yet been carried out, and consideration of this topic remains at the preliminary stage and requires further investigation. In this study, systemic bioinformatic analysis was carried out on the genome-wide AS events of 555 clinical HNSCC samples from the TCGA database. Firstly, we statistically analyzed the distributions of seven AS event types in HNSCC samples. Then, through univariate survival analysis, we observed the relationship between AS and the prognosis of the disease and found that 437 intersections of AS events were significantly related to overall survival. Among them, 335 cross-genes showed a high degree of consistency in the genes associated with overall survival and recurrence. The overall survival was significantly related to AS events. Besides, the frequency of overall survival-related ES events was evidently reduced, while the AP and the AT events were increased. In addition, AT events accounted for the largest proportion. Further, multiple regression model analysis proved that AS could become a new classification method for HNSCC, and KEGG enrichment analysis proved that most genes and proteins interacting with AS events had different biological functions and were associated with a variety of diseases. Finally, through the selection of characteristic HNSCC genes and the construction of a prognostic model, seven cross-genes related to survival and recurrence were screened out, and these characteristic genes were verified by multivariate survival model analysis so as to classify the prognosis at different splicing times and gene expression levels. These results have laid a solid foundation for our further research and play a decisive role in showing the correlation of AS with the prognosis of HNSCC.

Comprehensive characterization of the alternative splicing landscape in head and neck squamous cell carcinoma reveals novel events associated with tumorigenesis and the immune microenvironment

Alternative splicing (AS) has emerged as a key event in tumor development and microenvironment formation. However, comprehensive analysis of AS and its clinical significance in head and neck squamous cell carcinoma (HNSC) is urgently required. Methods: Genome-wide profiling of AS events using RNA-Seq data from The Cancer Genome Atlas (TCGA) program was performed in a cohort of 464 patients with HNSC. Cancer-associated AS events (CASEs) were identified between paired HNSC and adjacent normal tissues and evaluated in functional enrichment analysis. Splicing networks and prognostic models were constructed using bioinformatics tools. Unsupervised clustering of the CASEs identified was conducted and associations with clinical, molecular and immune features were analyzed. Results: We detected a total of 32,309 AS events and identified 473 CASEs in HNSC; among these, 91 were validated in an independent cohort (n = 15). Functional protein domains were frequently altered, especially by CASEs affecting cancer drivers, such as PCSK5. CASE parent genes were significantly enriched in pathways related to HNSC and the tumor immune microenvironment, such as the viral carcinogenesis (FDR < 0.001), Human Papillomavirus infection (FDR < 0.001), chemokine (FDR < 0.001) and T cell receptor (FDR < 0.001) signaling pathways. CASEs enriched in immune-related pathways were closely associated with immune cell infiltration and cytolytic activity. AS regulatory networks suggested a significant association between splicing factor (SF) expression and CASEs and might be regulated by SF methylation. Eighteen CASEs were identified as independent prognostic factors for overall and disease-free survival. Unsupervised clustering analysis revealed distinct correlations between AS-based clusters and prognosis, molecular characteristics and immune features. Immunogenic features and immune subgroups cooperatively depict the immune features of AS-based clusters. Conclusion: This comprehensive genome-wide analysis of the AS landscape in HNSC revealed novel AS events related to carcinogenesis and immune microenvironment, with implications for prognosis and therapeutic responses.