Biology subjects

Stott, S. L.

Publications and source records attributed to Stott, S. L..

5 recordsLinked to original sources

bioRxiv2026

Chemotherapy-induced transfer of apoptotic machinery in extracellular vesicles between somatic and germ cells of the testis: mechanistic insights into onco-fertility preservation in pre-pubertal boys

Extracellular vesicles (EVs) are increasingly recognized as critical mediators of intercellular communication, not least during cellular stress or therapy. While EV signalling is well-studied in various tissues, its role in the prepubertal testicular environment is not well understood. Chemotherapy, commonly used in paediatric oncology, poses a significant risk to spermatogonial stem cells (SSCs) and may affect long-term fertility in cancer survivors. The role of EVs in chemotherapy-induced testicular damage in these patients is unknown and may be important for developing new fertility preservation methods. Immortalised murine Sertoli (TM4) and spermatogonial (GC1-spg) cell lines were used to investigate cisplatin-induced changes in EV biogenesis, release, and function in an in vitro model of the prepubertal testicular microenvironment. Our findings indicate that cisplatin significantly increases EV secretion and internalisation by recipient cells. Notably, EVs from cisplatin-exposed Sertoli cells exhibit a novel pro-apoptotic phenotype when co-cultured with chemotherapy-naive Sertoli cells. Proteomic profiling of these EVs shows enrichment of apoptosis-regulatory proteins including caspases, activating Caspase-3/7 in recipient Sertoli cells. Conversely, germ cells exposed to Sertoli cell-derived EVs displayed reduced levels of apoptosis as well as a chemoprotective role to germ cells undergoing treatment with cisplatin. These findings indicate a dual role for Sertoli cell-derived EVs in mediating (1) apoptosis in Sertoli cells and (2) protection of germ cells following cisplatin exposure. The presence of pro-apoptotic molecules, especially caspases, in chemotherapy-induced Sertoli cell EVs provides mechanism for the induction of somatic cell apoptosis. Furthermore, their protective effects on germ cells demonstrate the complexity of EV-mediated signalling between testicular cell types. Manipulating EV biogenesis and cargo loading could be a promising approach to reduce chemotherapy-related gonadotoxicity and preserve fertility in childhood cancer patients.

cell biology↗

bioRxiv2024

Dendritic cell effector mechanisms and tumor immune microenvironment infiltration define TLR8 modulation and PD-1 blockade

The potent immunostimulatory effects of toll-like receptor 8 (TLR8) agonism in combination with PD-1 blockade have resulted in various preclinical investigations, yet the mechanism of action in humans remains unknown. To decipher the combinatory mode of action of TLR8 agonism and PD-1 blockade, we employed a unique, open-label, phase 1b pre-operative window of opportunity clinical trial (NCT03906526) in head and neck squamous cell carcinoma (HNSCC) patients. Matched pre- and post-treatment tumor biopsies from the same lesion were obtained. We used single-cell RNA sequencing and custom multiplex staining to leverage the unique advantage of same-lesion longitudinal sampling. Patients receiving dual TLR8 agonism and anti-PD-1 blockade exhibited marked upregulation of innate immune effector genes and cytokines, highlighted by increased CLEC9A+ dendritic cell and CLEC7A/SYK expression. This was revealed via comparison with a previous cohort from an anti-PD-1 blockade monotherapy single-cell RNA sequencing study. Furthermore, in dual therapy patients, post-treatment mature dendritic cells increased in adjacency to CD8+ T-cells. Increased tumoral cytotoxic T-lymphocyte densities and expanded CXCL13+CD8+ T- cell populations were observed in responders, with increased tertiary lymphoid structures (TLSs) across all three patients. This study provides key insights into the mode of action of TLR8 agonism and anti-PD-1 blockade immune targeting in HNSCC patients.

immunology↗

bioRxiv2024

Distinct phenotypic consequences of cholangiocarcinoma-associated FGFR2 alterations depend on biliary epithelial maturity

Epithelial cancers disrupt tissue architecture and are often driven by mutations in genes that play important roles in normal epithelial morphogenesis. The intrahepatic biliary system is an epithelial tubular network that forms within the developing liver via the de novo initiation and expansion of apical lumens. Intrahepatic biliary tumors (intrahepatic cholangiocarcinoma) commonly harbor activating genomic alterations in the FGFR2 receptor tyrosine kinase, which plays important roles in epithelial morphogenesis in other developmental settings. Using a physiologic and quantitative 3D model we demonstrate that FGFR signaling is important for biliary morphogenesis and that oncogenic FGFR2 fusions and in-frame deletions disrupt biliary architecture. Importantly, we show that the trafficking of and signaling from the FGFR2 mutants, as well as their phenotypic impacts, are governed by the epithelial state of the cell. Unexpectedly, we also found that distinct tumor-driving FGFR2 mutants disrupt biliary morphogenesis in completely different and clinically relevant ways, informing our understanding of morphogenesis and tumorigenesis and highlighting the importance of convergent studies of both.

cancer biology↗

bioRxiv2022

Viral proteins and virus-like particles of the LTR5_Hs endogenous retrovirus in human primordial germ cell-like cells

The hominoid-specific endogenous retrovirus LTR5_Hs is transcriptionally activated in human primordial germ cell-like cells (hPGCLCs), a pluripotent stem cell-derived cell culture model of PGCs. Here, taking the unique advantage of our novel cell culture method to obtain large amounts of pure hPGCLCs, we performed proteomics profiling of hPGCLCs and detected various viral proteins produced from the LTR5_Hs RNA via ribosomal frameshifting. We also present transmission electron microscopy images of 100-nm diameter virus-like particles (VLPs) assembled at the surface of hPGCLCs. Compared to hPGCLCs, expression of LTR5_Hs RNA is far weaker in human seminomas, the germ cell tumors resembling PGCs. Re-analysis of published single cell RNA-seq data of human embryos revealed strong activation of LTR5_Hs in migrating PGCs but suppressed in PGCs upon they reach the gonadal anlagen. In the microfluidics-supported polarized embryoids mimicking peri-implantation stages of human embryos, LTR5_Hs RNA was detected by RNA in situ hybridization in NANOG+/TFAP2C+/SOX17+ cells resembling freshly emerged PGCs. These results support that human germ cells produce LTR5_Hs proteins and VLPs during their earliest stages of normal development until their settlement in the gonadal anlagen. SUMMARY STATEMENTThe hominoid-specific endogenous retrovirus LTR5_Hs is activated in a cell culture model resembling early-stage human primordial germ cells, producing not only viral RNA but also retrovirus proteins and virus-like particles.

developmental biology↗

bioRxiv2021

Single cell proteomics of tumor compartments identifies differential kinase activities defining sensitivity to mTOR-PI3-kinase inhibition

Cancer therapy often results in heterogeneous responses in different metastatic lesions in the same patient. Inter- and intra-tumor heterogeneity in proteomic signaling within the various tumor compartments and its impact on therapy are not well characterized due to the limited sensitivity of single cell proteomic approaches. To overcome this barrier, we applied single cell mass cytometry with a customized 29-antibody panel [against cell states, receptor tyrosine kinases (RTK) and phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR)-, mitogen-activated protein kinase (MAPK)-, and cytokine-signaling] to PTEN-deleted orthotopic prostate cancer xenograft models to measure the evolution of kinase activities in different tumor compartments during metastasis and upon drug treatment. Compared with primary tumors and circulating tumor cells (CTCs), bone metastases but not lung and liver metastases exhibited elevated PI3K/mTOR signaling and RTKs including c-Met protein, which, when suppressed, impaired tumor growth in the bone. Intra-tumoral heterogeneity within tumor compartments also arises from highly proliferative EpCAMhigh epithelial cells with increased PI3K and mTOR kinase activities co-existing with poorly proliferating EpCAMlow mesenchymal populations with reduced kinase activities, findings recapitulated in epithelial and mesenchymal CTC populations in metastatic prostate and breast cancer patients. Increased kinase activity in EpCAMhigh cells rendered them more sensitive to PI3K/mTOR inhibition and drug resistant EpCAMlow populations with reduced kinase activity emerged over time. Taken together, single cell proteomics identified microenvironment- and cell state-dependent activation of kinase networks creating heterogeneity and differential drug sensitivity among and within tumor populations across different sites, defining a new paradigm of drug responses to kinase inhibitors.

cancer biology↗