Expression profiles of angiogenic growth factors in squamous cell carcinomas of the head and neck

Abstract

Inhibition of angiogenesis by blocking angiogenic cytokines or their pathways has become a major target in experimental cancer therapies. This therapeutical approach requires a profound knowledge of growth factor profiles that contribute to tumor growth and progression. The respective knowledge is presently rather incomplete for head and neck squamous cell carcinomas (HNSCC). Therefore we studied expression of several angiogenic cytokines including VEGF, bFGF, PDGF‐AB, PDGF‐BB, G‐CSF and GM‐CSF in HNSCC in vivo and in vitro. In tumor tissues expression of all cytokines was observed albeit with marked differences concerning intensity and distribution pattern. Quantification of the cytokines in the supernatant of 15 tissue‐corresponding HNSCC cultures revealed that VEGF, PDGF‐AB and less frequently GM‐CSF were secreted in high amounts of up to 13 ng/ml/10⁶ cells. Twenty percent of the HNSCC cultures expressed only 1 cytokine in biologically active amounts, 60% 2 or 3 and 20% expressed the maximum of 4 cytokines simultaneously. Interestingly, we observed a distinct cytokine pattern: HNSCC cells secreting only 1 or 2 cytokines presented always with either VEGF and/or PDGF‐AB, while G‐CSF and GM‐CSF were secreted primarily together with VEGF and PDGF‐AB. The number of cytokines expressed by HNSCC cells correlated with the microvessel density of the original tumor and with the clinical outcome: tumors producing at least 3 cytokines revealed a significantly poorer patient prognosis. Our data indicate a major role for VEGF and PDGF‐AB in HNSCC and that the additional secretion of G‐CSF or GM‐CSF might contribute to a poorer prognosis in patients suffering from these tumors.