Angiosarcomas are rare malignant tumors of the endothelium, arising commonly from the head and neck region (AS-HN) and recently associated with ultraviolet (UV) exposure and human herpesvirus-7 infection. We examined 81 cases of angiosarcomas, including 47 cases of AS-HN, integrating information from whole genome sequencing, gene expression profiling and spatial transcriptomics (10X Visium). In the AS-HN cohort, we observed recurrent somatic mutations in CSMD3 (18%), LRP1B (18%), MUC16 (18%), POT1 (16%) and TP53 (16%). UV-positive AS-HN harbored significantly higher tumor mutation burden than UV-negative cases (p = 0.0294). NanoString profiling identified three clusters with distinct tumor inflammation signature scores (p < 0.001). Spatial transcriptomics revealed topological profiles of the tumor microenvironment, identifying dominant but tumor-excluded inflammatory signals in immune-hot cases and immune foci even in otherwise immune-cold cases. In conclusion, spatial transcriptomics reveal the tumor immune landscape of angiosarcoma, and in combination with multi-omic information, may improve implementation of treatment strategies.

The field of immuno-oncology is now at the forefront of cancer care and is rapidly evolving. The immune checkpoint blockade has been demonstrated to restore antitumor responses in several cancer types. However, durable responses can be observed only in a subset of patients, highlighting the importance of investigating the tumor microenvironment (TME) and cellular heterogeneity to define the phenotypes that contribute to resistance as opposed to those that confer susceptibility to immune surveillance and immunotherapy. In this review, we summarize how some of the most widely used conventional technologies and biomarkers may be useful for the purpose of predicting immunotherapy outcomes in patients, and discuss their shortcomings. We also provide an overview of how emerging single-cell spatial omics may be applied to further advance our understanding of the interactions within the TME, and how these technologies help to deliver important new insights into biomarker discovery to improve the prediction of patient response.

Angiosarcomas, clinically aggressive cancers of endothelial origin, are a rare subtype of soft-tissue sarcomas characterized by resistance to chemotherapy and dismal prognosis. In this study, we aim to identify the transcriptomic biomarkers of chemoresistance in angiosarcoma. We examined 72 cases of Asian angiosarcomas, including 35 cases treated with palliative chemotherapy, integrating information from NanoString gene expression profiling, whole transcriptome profiling (RNA-seq), immunohistochemistry, cell line assays, and clinicopathological data. In the chemoresistant cohort (defined as stable disease or progression), we observed the significant overexpression of genes, including SPP1 (log2foldchange 3.49, adj. p = 0.0112), CXCL13, CD48, and CLEC5A, accompanied by the significant enrichment of myeloid compartment and cytokine and chemokine signaling pathways, as well as neutrophils and macrophages. RNA-seq data revealed higher SPP1 expression (p = 0.0008) in tumor tissues over adjacent normal compartments. Immunohistochemistry showed a significant moderate positive correlation between SPP1 protein and gene expression (r = 0.7016; p < 0.00110), while higher SPP1 protein expression correlated with lower chemotherapeutic sensitivity in patient-derived angiosarcoma cell lines MOLAS and ISOHAS. In addition, SPP1 mRNA overexpression positively correlated with epithelioid histology (p = 0.007), higher tumor grade (p = 0.0023), non-head and neck location (p = 0.0576), and poorer overall survival outcomes (HR 1.84, 95% CI 1.07–3.18, p = 0.0288). There was no association with tumor mutational burden, tumor inflammation signature, the presence of human herpesvirus-7, ultraviolet exposure signature, and metastatic state at diagnosis. In conclusion, SPP1 overexpression may be a biomarker of chemoresistance and poor prognosis in angiosarcoma. Further investigation is needed to uncover the precise roles and underlying mechanisms of SPP1.

Cancer therapies developed using bacteria and their components have been around since the 19th century. Compared to traditional cancer treatments, the use of bacteria-derived compounds as cancer therapeutics could offer a higher degree of specificity, with minimal off-target effects. Here, we explored the use of soluble bacteria-derived toxins as a potential squamous cell carcinoma (SCC) therapeutic. We optimized a protocol to generate Staphylococcus aureus biofilm-conditioned media (BCM), where soluble bacterial products enriched in the development of biofilms were isolated from a bacterial culture and applied to SCC cell lines. Bioactive components of S. aureus ATCC 29213 (SA29213) BCM display selective toxicity towards cancerous human skin SCC-12 at low doses, while non-cancerous human keratinocyte HaCaT and fibroblast BJ-5ta are minimally affected. SA29213 BCM treatment causes DNA damage to SCC-12 and initiates Caspase 3-dependent-regulated cell death. The use of the novel SA29213 bursa aurealis transposon mutant library led to the identification of S. aureus alpha hemolysin as the main bioactive compound responsible for the observed SCC-12-specific toxicity. The antibody neutralisation of Hla eradicates the cytotoxicity of SA29213 BCM towards SCC-12. Hla displays high SCC-12-specific toxicity, which is exerted primarily through Hla-ADAM10 interaction, Hla oligomerisation, and pore formation. The high target specificity and potential to cause cell death in a controlled manner highlight SA29213 Hla as a good candidate as an alternative SCC therapeutic.

The opportunistic pathogen Staphylococcus aureus has an extremely complex relationship with humans. While the bacteria can exist as a commensal in many, it can cause a wide range of diseases and infections when turned pathogenic. Its presence is a determinant of chronicity and poor prognosis in numerous diseases, and its genomic plasticity causes S. aureus antimicrobial resistance to be one of the most dire contemporary medical problems to solve. Genetic manipulation of S. aureus has led to numerous findings that are vital in the fight against its pathogenesis. The utilisation of transposon mutant libraries for the systematic inspection of the S. aureus genome led to many landmark discoveries pertaining to the bacteria’s pathogenicity, antimicrobial resistance acquisition, and virulence regulation. In this review, we describe mutant libraries, and their significant contributions, from various S. aureus strains created with commonly used transposons. The general workflow for the construction of libraries will be presented, along with a discussion of the challenges of undertaking the task of large-scale library construction. As the accessibility of transposon mutant library construction, screening, and analysis increases, this genetic tool could be further exploited in the study of the S. aureus genome.