Background:
Expression of fas receptors renders tumor cells potentially susceptible to the host immune system. in squamous cell carcinomas of the head and neck, fas has recently been found to be down-regulated in some cases; its prognostic value and correlation with clinicopathologic parameters, however, is yet to be delineated.
Methods:
Paraffin-embedded specimens of 88 primary laryngeal squamous cell carcinomas were investigated for fas protein expression by immunohistochemistry. apoptotic tumor cells were visualized using the nick end labeling method. to assess the immunologic reaction to the neoplasm, the intensity of lymphoplasmocytic stroma reaction was determined. the mean follow-up time amounted to 45.9 months (range, 1-144 months).
Results:
In tumor-adjacent normal mucosa and in most well-differentiated tumors, fas expression was restricted to basal and parabasal cell layers. a diffuse pattern of staining reactions predominated in high-grade lesions (p <.001). the degree of fas expression revealed a positive relationship with the intensity of lymphoplasmocytic stroma reaction (p =.002) but was unrelated to clinicopathologic parameters and to apoptotic rates of tumors. neither fas nor the lymphoplasmocytic stroma reaction had any impact on patient survival.
Conclusions:
Up-regulation of cell surface fas expression in laryngeal carcinoma seems to have a stimulatory effect on the immune cell infiltration of the stromal tissue. its lack of clinical relevance might be due to an inhibition of intracellular fas signal transduction, which represents a frequent strategy of tumor cells to escape fas-mediated apoptosis.