TGF-alpha protein and receptor localization in laryngotracheal tissue

Model for evaluating the effect of growth factors on the larynx

Growth factors are proteins that help regulate the inflammatory response and wound healing in tissues. After laryngotracheal surgery, proper wound healing is important in maintaining the reconstructed airway. The application of growth factor to the respiratory mucosa of the larynx and its effect on wound healing within the airway have not been studied. This study was designed to establish a model for the evaluation of wound healing after the application of growth factor to composite respiratory mucosa and cartilage surfaces at the time of laryngotracheoplasty. Forty rabbits underwent anterior cricoid cartilage split with or without the use of a cartilage graft. Platelet-derived growth factor or a placebo substance was applied to the wound at the time of surgery. This study offers a model for studying wound healing in the airway that is reproducible with limited morbidity.

Quantitative immunohistochemical analysis of transforming growth factor-alpha and epidermal growth factor receptor in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) mRNA are up-regulated in squamous cell carcinoma of the head and neck (SCCHN) tissues.

METHODS

Immunohistochemical staining with monoclonal antibodies to TGF-alpha and EGFR was undertaken to identify the cellular origin in tissue obtained from cancer patients and controls and to determine the correlation between mRNA expression levels and two methods of immunohistochemical evaluation.

RESULTS

TGF-alpha protein staining occurred in the suprabasal layers and spared the basal layer of normal controls. Conversely, in histologically normal mucosa from SCCHN patients, TGF-alpha was present throughout the epithelium, including the basal layer. EGFR staining was negligible in normal mucosa from control patients without cancer and relatively increased in SCCHN tissues. Increasing staining intensity was correlated with worsening dysplasia and closer proximity to the tumor. Using computerized image analysis to quantify the intensity of immunostaining, the mean optical density (MOD) of TGF-alpha staining in histologically normal mucosa (P = 0.049) and tumors (P = 0.005) from SCCHN patients was significantly higher than in control normal mucosa from noncancer patients (1.9- and 1.7-fold, respectively). EGFR MOD was also greater in the histologically normal mucosa (P = 0.009) and tumors (P = 0.006) from SCCHN patients than in control normal mucosa (1.8- and 1.9-fold, respectively). For both TGF-alpha (P = 0.668) and EGFR (P = 0.116), the MOD was similar for both tumor and histologically normal mucosa from SCCHN patients.

CONCLUSIONS

TGF-alpha and EGFR protein expression is increased early in head and neck squamous cell carcinogenesis and can be quantitated by computerized image analysis of immunohistochemical staining. Altered distribution of TGF-alpha protein in histologically normal mucosa from SCCHN patients compared with control mucosa from patients without cancer suggests a switch from a paracrine to an autocrine pathway.