Hypoxia-induced tumor-derived exosomes increased endothelial secretion of CCL26 and promoted tumor-associated phenotypes in head and neck squamous cell carcinoma, with these effects reduced by CCL26 neutralization or genetic silencing of the CCL26 receptor CCR3, according to findings published in Head & Neck.
Researchers modeled hypoxia using cobalt chloride–treated head and neck squamous cell carcinoma cell lines Cal 27, Detroit-562, and FaDu. Exosomes from normoxic and hypoxic conditions were applied to human umbilical vein endothelial cells, and the endothelial secretome was profiled using cytokine arrays covering 120 proteins, with enzyme-linked immunosorbent assay validating chemokine levels. Functional assays assessed cell viability, migration, invasion, and endothelial tube formation. Additional analyses included transcriptomic data sets and immunohistochemistry in tumor samples from 23 patients with nonmetastatic disease and 24 patients with metastatic disease.
Hypoxic exosomes altered 25 proteins in endothelial secretomes derived from Detroit-562 cells and 52 proteins in those derived from FaDu cells, with most changes reflecting increased protein levels. CCL26 was among the chemokines consistently increased, and enzyme-linked immunosorbent assay confirmed higher levels following hypoxic vs normoxic exosome exposure.
CCL26-enriched secretomes increased viability, migration, and invasion of head and neck squamous cell carcinoma cells and enhanced endothelial tube formation. Neutralization of CCL26 reduced these effects, and genetic silencing of CCR3 produced similar reductions in tumor-associated phenotypes. These findings were based on in vitro assays and require validation in vivo.
In translational analyses, expression of CCL26 and hypoxia-inducible factor 1 alpha was higher in tumor vs normal tissue samples. CCL26 expression was also higher in metastatic vs primary tumors. Higher expression of both markers was associated with advanced stage, higher grade, lymph node involvement, and poorer overall survival. Immunohistochemistry showed stronger staining for both markers in metastatic tumors, while CD31 expression did not differ between metastatic and nonmetastatic samples.
The researchers noted limitations, including lack of validation under controlled hypoxic chamber conditions, absence of rescue experiments using recombinant CCL26, and lack of epitope-independent validation of CCL26 neutralization approaches.
“Hypoxia-induced exosomes derived from HNSCC cells can significantly reshape the protein profile of recipient endothelial cell secretomes, primarily through the presence of elevated CCL26 chemokine,” wrote lead researcher Ozel Capik of Erzurum Technical University and colleagues.
Disclosures: The researchers reported no conflicts of interest.
Source: Head & Neck
