Abstract

HNSCC, being a global health concern, is the seventh most common cancer worldwide. The exosomes released by these tumor cells play a significant role in immunoregulation and HNSCC progression. However, the specific role of exosomes released by Cal27-HNSCC cells is yet to be studied

Methods

Cal27 cell lines are cultured in DMEM with 10% exosome-depleted FBS, for exosome isolation. Cell surface markers were determined on Cal27 tumor cells by flow cytometry. The exosomes are isolated from cell culture supernatants using size exclusion chromatography and the physical characteristics like size and morphology were measured using dynamic light scattering and transmission electron microscopy. The surface of these isolated exosomes was characterized for well-known tumor markers like Hsp70, CD9, CD63, and CD81 using flow cytometry. The binding affinity of surface Hsp70 positive exosomes to cmHsp70.1 monoclonal antibody (mAb) was determined by microscale thermophoresis and the influence of Cal27 derived exosomes on cytotoxic capacity of NK cells against Cal27 cells was investigated in cell death assays

Results

Cal27-derived exosomes, with an average size distribution of ~100 nm, exhibit various cell-surface markers and possess significant immunomodulatory effects on NK cells. Our study reveals that Cal27 cells, besides tetraspanins (CD9, CD63, and CD81), express different immunoregulatory ligands (eg, PD-L1, HLA-E, Hsp70) for NK cells. Upon co-incubation of monocytes with Cal27-derived exosomes, we observed an impaired immune response and cytotoxicity of treated NK cells against tumor cells

Discussion

Our findings highlight key implications for understanding HNSCC progression and developing a site-specific therapeutic strategy to modulate anti-cancer immune response

The authors declare that they have no conflict of interest.