Cells of the tumor front: A potential therapeutic target in head and neck cancer therapy? [Zellen der Tumorfront: Ein m?gliches therapeutisches Ziel bei der Behandlung von Kopf-Hals-Karzinomen?]

摘要

Background: With a frequency of about 90 %, head and neck squamous cell carcinomas (HNSCCs) are the most common malignancies of the upper aerodigestive tract. The cancer stem cell (CSC) hypothesis postulates that CSCs are the dangerous part of the tumor and are relevant to metastasis, invasiveness and resistance to chemotherapy. Methods: Tissue samples taken from HNSCCs and normal mucosa were tested for the expression of several established CSC markers. The expression and activity of the matrix metalloproteinase MMP-9 was also investigated. Results: Cells of the invasive tumor front expressed the basal stem cell markers CD44, ALDH1 and CK14. However, in contrast to the noninvasive basal cell layer of normal mucosa, HNSCC samples were also positive for active MMP-9, which lends the tumor its gelatinolytic activity. Conclusion: These observations suggest a model in which cells of the invasive front are derived from the basal cell layer of normal mucosa and harbour the CSCs. Future studies should thus focus on the cells of the invasive front in particular, since the activity of these cells may form the basis for tumor recurrence and therapy resistance.