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Abstract Tissue fibrosis and extracellular matrix (ECM) stiffening have been shown to promote tumor cell proliferation, metastasis, and chemoresistance in a range of cancers. Stiffness of the ECM can lead to changes in cancer cell behavior, including enhanced proliferation, activation of mechano-sensitive signaling pathways, and potential genomic damage, with implications for cancer progression and immune responses. Recent research suggests stiff matrix may also induce the release of tumor-derived small extracellular vesicles (sEVs) that promote tumor growth. Tumor-derived sEVs carry bioactive cargo, such as micro-RNAs (miRNAs) and DNA fragments, and function as a unique form of intracellular communication promoting cell survival, growth, and metastasis. Understanding these mechano-sensing mechanisms is essential for identifying potential targets in precision medicine for solid tumor treatment. However, the influence of tumor stiffness on secretory cues, and their subsequent role in immunomodulation and/or chemo-resistance has not been extensively studied. This project aims to explore how tumor stiffness can alter cell responses to genotoxic stress and how these responses can perpetuate feedback to the immune system through the release of secretory cues such as sEVs. Here, we outline the isolation and characterization of tumor-derived sEVs obtained from culture media of oral squamous cell carcinoma (OSCC) spheroids, cultured at varying stiffness (0. 2kPa-1. 5kPa). In this project, we use OSCC lines that are either sensitive or resistant to cisplatin (HSC-3 and HN-5, respectively). To explore the immunomodulatory effects of these tumor-derived sEVs, we first established a consistent supply of CD206+ve macrophages differentiated from human induced pluripotent stem cells (iMacs), following the established protocol of Douthwaite et al (2021). iMacs were then treated with sEVs with their resulting immunophenotype, and activation assessed. These preliminary experiments provide a step towards understanding how the biophysical environment influences tumor cell resistance to therapy and how sEVs can modulate the relationship between cancer cells and macrophages. Citation Format: Bethany R. Bareham, Matthew Dibble, Leila Mouhib, Aitor Bermejo Arteagabeitia, Subhankar Mukhopadhyay, Maddy Parsons. Mechano-chemical control of secretory cues regulating immune tolerance, survival and invasion in oral squamous cell carcinomas abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5569.
Bareham et al. (Fri,) studied this question.