gms | German Medical Science

Introduction: Head and neck squamous cell carcinomas (HNSCC) are characterized by their early, primarily lymphatic metastatic spread and dramatic drop in the patients survival time if lymph node metastases are present at the time of diagnosis. After surgical removal of the primary tumor, radio(chemo)therapy is frequently added to the treatment scheme to target remaining tumor cells and induce programmed cell death, also known as apoptosis. However, regularly HNSCC tumors exhibit resistance to apoptosis induction. Also it was found that overexpression of the epidermal growth factor receptor (EGFR) is associated with poor prognosis of HNSCC patients. In this study, we therefore used HNSCC-derived cell lines to assess the influence EGFR stimulation has on the expression of anti apoptotic proteins. Materials and methods: 10 previously characterized HNSCC cell lines were used in this study. Stimulation of cell lines was performed with rising concentrations of EGF (0,0.1,1,10,100 and 1000ng/ml) for 12h. Western blot analysis was done under standard conditions. Actin was used as an input control.

Results: All cell lines exhibited Bcl-xL up-regulation after stimulation with 100ng/ml EGF. Some cell lines responded with Bcl-xL up-regulation at much lower EGF concentrations (0.1ng/ml) than other, that required significantly higher (10-100ng/ml) EGF levels.

Conclusion: EGFR-stimulation results in a variable up-regulation of Bcl-xL. Since different cell lines responded with a different sensitivity to EGFR-Stimulation it is likely that among different HNSCC-tumors in vivo there is also a significant difference in the extent of EGFR-dependent Bcl-xL expression. This potentially could explain, to some extent, the variable apoptosis resistance of HNSCC tumors as observed in a subgroup of HNSCC patients.