Inhibition of transforming growth factor alpha stimulation of human squamous cell carcinoma of the head and neck with anti-TGF-alpha antibodies and tyrphostin

BACKGROUND

Transforming growth factor alpha (TGF-alpha) and its receptor (EGF-R) may regulate normal and malignant epithelial cell growth by an autocrine mechanism. We investigated the role of TGF-alpha in regulating head and neck SCC tumor growth.

METHODS

TGF-alpha and EGF-R levels were measured in 7 SCC cell lines and 14 SCC biopsies by RIA, Scatchard, and Western analysis. TGF-alpha autocrine stimulation of DNA synthesis in SCC cell lines was assessed by incubation with TGF-alpha neutralizing antibodies and tyrphostin AG 1478, a selective and potent inhibitor of EGF-R kinase.

RESULTS

All SCC cell lines synthesized TGF-alpha and expressed elevated EGF-R levels compared to normal keratinocytes. Twelve of the 14 SCC biopsies contained TGF-alpha protein and 8 had specific EGF-R. Exogenous TGF-alpha or EGF significantly increased DNA synthesis in 4 of 5 SCC cell lines. TGF-alpha neutralizing antibodies or tyrphostin AG 1478 reduced DNA synthesis in the two SCC cell lines (FaDu and SCC9) tested.

CONCLUSIONS

These results indicate that SCC cell lines and tumors usually synthesize TGF-alpha, have elevated levels of EGF-R, and are mitogenically stimulated by a TGF-alpha autocrine system. Selective inhibition of the TGF-alpha system by EGF-R kinase inhibitors or TGF-alpha neutralizing antibodies may be useful strategies for treating SCC that overexpress TGF-alpha and its receptor.

Surgical management of velopharyngeal dysfunction: outcome analysis of autogenous posterior pharyngeal wall augmentation

Posterior pharyngeal wall augmentation has been advocated for patients having velopharyngeal dysfunction with a small coronal gap. Nonautogenous augmentation has not been accepted widely because of migration or extrusion of alloplastic implants and resorption of injected materials. Autogenous posterior pharyngeal wall augmentation has been performed for decades by Italian surgeons. A retrospective study was conducted to evaluate the efficacy of this procedure. Autogenous posterior pharyngeal wall augmentation, using a rolled superiorly based pharyngeal myomucosal flap, was performed on 14 patients, between November of 1989 and June of 1992, who fulfilled two criteria: velopharyngeal dysfunction unresponsive to speech therapy and a small (< 20 percent) coronal gap on velopharyngeal nasendoscopy. Of these, 3 patients had prior prosthetic velopharyngeal management, including 2 patients with Robin sequence. All patients were evaluated preoperatively and 3 months postoperatively with recorded (audio-videotape) perceptual, nasendoscopic, and fluoroscopic standardized speech and airway evaluations. The tapes were used for construction of a randomized master tape that was presented in blinded fashion and random order to three skilled raters for independent assessment of numerous perceptual and instrumental parameters of speech. The raters were uninvolved in the care of the patients or this study, and their intraobserver and interobserver reliabilities were known. Preoperatively, the majority of patients had nasal turbulence. All patients had variable degrees of hypernasality ranging from intermittent to pervasive. Parameters rated included (1) resonance (hypernasality, hyponasality, mixed), (2) auditory nasal emission (including nasal turbulence), and (3) visual characteristics regarding velopharyngeal closure. The visual parameters consisted of questions about whether a pharyngeal bulge was present or absent, descriptions of posterior pharyngeal wall movements with speech, level of closure, completeness of velopharyngeal closure, and quantitative descriptions of the percentage of velopharyngeal closure postoperatively. Examiners were instructed to look for a static and/or dynamic projection or bulge (i.e., Passavant's ridge) and, if a bulge was present, whether the level of velopharyngeal closure was on the same plane as the neoposterior pharyngeal bulge. Results of the extramural judgments of these parameters showed that there was no statistically significant tendency for patients' speech to be rated as more normal after the augmentation procedure than before it. We conclude that (1) autogenous posterior pharyngeal wall augmentation does not result in speech improvement and (2) autogenous posterior pharyngeal wall augmentation does not impair the nasal airway.

Impact of diagnosis-related groups on the quality of postoperative care of patients with neck dissections

Two hundred eighty patients underwent neck dissection over a 10-year period: 138 during the 5-year period before the institution of Diagnosis-Related Group (DRG) reimbursement and 142 during the 5 years after DRG regulations. A comparison of these two groups by site of tumor, stage of disease, histopathology, previous treatment, type of neck dissection, whether neck dissection was carried out alone or in combination with another procedure, presence of preexisting disease, postoperative complications, and mortality revealed no significant differences. A 35% reduction in the length of hospital stay from 16 to 10 days was identified in the post-DRG group with no detrimental effects on patient care. The variables found to have the greatest impact on length of hospital stay were the extent of operation and postoperative complications.

Lip reconstruction with motor and sensory innervated composite flaps

Among the most elegant of recent flap refinements are innervated composite skin-muscle-mucosal flaps that restore the oral sphincter and carry both motor and sensory nerves. These flaps are based on the orbicularis oris, depressor anguli oris, and levator anguli oris perioral muscles of facial expression. Each flap can be dissected in a manner that allows transfer of the muscle into the oral sphincteric ring while restoring lip form and preserves the motor and sensory innervation. Each flap can be designed to carry skin and mucosa as needed for cover, lining, and vermilion reconstruction. Choice is determined by the specific anatomic lip defects. The orbicularis oris flap is most useful for large central defects of either the upper or lower lip. The depressor anguli oris flap is most useful for lateral lower lip defects or total lower lip reconstruction with bilateral flaps. The levator anguli oris is most useful for upper lip lateral element defects or for total upper lip restoration with bilateral flaps and an Abbe flap philtral reconstruction. Innervated composite flaps demonstrate substantial advantages when compared with preceding methods because of the superior function conveyed by the sphincter reconstruction and preserved motor and sensory nerve innervation.

Epidermal growth factor binding and action on tympanic membranes

A significant percentage of tympanic membrane (TM) perforations require some form of therapy to heal. Topical application of epidermal growth factor (EGF), a potent mitogen for epidermal and mesodermal cells, promotes healing of injuries in tissues histologically similar to TM, such as cornea and skin. We evaluated TM as a target tissue for EGF action. Specific, high affinity receptors for EGF were detected in TM (Kd = 3.1 nM, 150 fmol receptor/mg protein). Autoradiography of iodine 125-EGF binding to intact TMs revealed that EGF receptors were present on cells in the stratified squamous epithelial layer and in the stromal/mucoepithelial layer. Repetitive treatment of perforated cat TMs with 20 micrograms of EGF formulated in saline induced substantial hyperplasia of epithelial and stromal layers compared to paired TMs treated with saline. A single treatment of perforated cat TMs with 50 micrograms of EGF formulated in a hydrogel or in shredded Gelfoam produced significantly (p less than .05) smaller perforations at 6 days following the operation compared to paired TMs treated with vehicles. These results demonstrate that TM is a target tissue for EGF and that topical treatment with EGF stimulates healing of TM perforations.