CD44(+) tumor cells promote early angiogenesis in head and neck squamous cell carcinoma

The role of CD44 in progression of head and neck squamous cell carcinoma (HNSCC) has been controversial. The goal of this study was to study the effects of CD44(+) tumor cells on the initial stages of tumor angiogenesis and to evaluate CD44 as a potential marker of tumor angiogenesis. The CD44 gene expression was studied using the Cancer Genome Atlas (TCGA) Head and Neck Cancer data base. Expression levels of CD44 and of microvascular density (MVD) markers were assessed by immunohistochemistry performed with tissue microarrays in a cohort of 49 HNSCC patients, 11 patients with dysplasia and 12 control oral mucosa tissues. The 4-nitroquinoline-1-oxide oral carcinogenesis mouse model was used to study CD44 expression during carcinogenesis. Gelatin sponges seeded with CD44(+), CD44(-) and unsorted cancer cells suspended in Matrigel were implanted in NOD/SCID mice into a dorsal skinfold chamber and compared to non-seeded sponges as controls. Angiogenic response was assessed by intravital microscopy. In the TCGA analysis, CD44 gene expression correlated with various pro-angiogenic genes. In human HNSCC tissues, CD44 expression was upregulated and was associated with blood vessels, although no correlation between MVD and CD44 expression was found. During oral carcinogenesis CD44 expression was upregulated. In dorsal skinfold chambers, CD44(+) cells showed a significantly higher MVD than CD44(-) or unsorted cells (p < 0.001). The results indicate that CD44(+) cells contain pro-angiogenic factors and stimulate tumor angiogenesis in HNSCC. Thus, CD44 might emerge as a potential angiogenic biomarker and a therapeutic target for anti-angiogenic therapies.