Cutaneous Squamous Cell Carcinoma (cSCC) is a keratinocyte-derived skin cancer with an increasing incidence worldwide. Extracellular vesicles (EVs) are small membrane-bound vesicles that are produced by virtually all cells of the human body. EVs play important roles in intercellular communication in particular in the tumor microenvironment. Despite the essential role of the stroma in cSCC growth and progression little is known about the role and characteristics of cSCC-derived EVs. The goal of this project was to systematically characterize the cell surface markers of normal keratinocyte- and cSCC-derived EVs. To this end, EVs were isolated from conditioned medium of normal human epidermal keratinocytes (NHEKs) and human cSCC cell lines (UT-SCC-7, UT-SCC-111 and A431) by size-exclusion chromatography. EVs were characterized by nanoparticle tracking analysis (NTA) for size distribution and concentration. Tetraspanin-positive EVs were identified by FACS using specific antibodies recognizing CD9, CD63 or CD81. The expression of 37 surface proteins was analyzed by multiplex bead-based flow cytometry assay. Results from our analysis suggest that cSCC cell lines secrete an increased number of EVs relative to NHEKs. In terms of cell surface markers, we detected an unusual heterogeneity among cSCC cell lines: while there was a number of cell surface proteins that were expressed exclusively on cSCC-derived EVs there was no EV surface marker which was completely absent from NHEK-EVs but present on the EVs of all three cSCC cell lines. These results suggest that there is a substantial heterogeneity among cSCCs in terms of EV-surface markers, which could limit the utility of EVs in distinguishing healthy skin cells from cancer cells.

ESDR496 - Comprehensive analysis of extracellular vesicles surface markers produced by normal keratinocytes human cutaneous squamous cell carcinoma cell lines reveals phenotypic heterogeneity

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.