Protein-tyrosine kinases, oncogenes, and cancer.
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Animals↗
Biomedical subjects
J T Parsons
Publications and source records attributed to J T Parsons.
Cell adhesion or integrin clustering increases phosphorylation of a focal adhesion-associated tyrosine kinase.
We have recently shown that changes in tyrosine phosphorylation of a 130-kDa protein(s) (pp130) may be involved in integrin signaling (Kornberg, L., Earp, H.S., Turner, C., Prokop, and Juliano, R. L. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 8392-8396). One component of the pp130 protein complex reacts with an antibody generated against p125fak, which is a focal contact-associated tyrosine kinase (Schaller, M.D., Borgman, C. A., Cobb, B. S., Vines, R. R., Reynolds, A. B., and Parsons, J. T. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5192-5196). Both antibody-mediated integrin clustering and adhesion of KB cells to fibronectin leads to increased tyrosine phosphorylation of p125fak. The phosphorylation of p125fak is coincident with adhesion of cells to fibronectin and is maximal prior to cell spreading. Tyrosine phosphorylation of p125fak is induced when KB cells are allowed to adhere to fibronectin, collagen type IV, or laminin, but is not induced on polylysine. When KB cells are subjected to indirect immunofluorescence microscopy, p125fak colocalizes with talin in focal contacts. These data provide additional evidence that tyrosine kinases are involved in integrin signaling.
Animals↗
pp125FAK a structurally distinctive protein-tyrosine kinase associated with focal adhesions.
Expression of the Rous sarcoma virus-encoded oncoprotein, pp60v-src, subverts the normal regulation of cell growth, which results in oncogenic transformation. This process requires the intrinsic protein-tyrosine kinase activity of pp60v-src and is associated with an increase in tyrosine phosphorylation of a number of cellular proteins, candidate substrates for pp60v-src. We report here the isolation of a cDNA encoding a protein, pp125, that is a major phosphotyrosine-containing protein in untransformed chicken embryo cells and exhibits an increase in phosphotyrosine in pp60v-src-transformed chicken embryo cells. This cDNA encodes a cytoplasmic protein-tyrosine kinase which, based upon its predicted amino acid sequence and structure, is the prototype for an additional family of protein-tyrosine kinases. Immunofluorescence localization experiments show that pp125 is localized to focal adhesions; hence, we suggest the name focal adhesion kinase.
Amino Acid Sequence↗
The influence of dose and time on wound complications following post-radiation neck dissection.
Data on 205 patients who were treated with a planned unilateral neck dissection following radiation therapy were analyzed with the purpose of understanding how treatment factors affect the incidence of wound complications. There were 27 occurrences of wound complication in the patient series. Logistic regression was used to analyze the data. We found that the surgical technique of flap reconstruction gave a significant increase in wound complications. There was a suggestion, although not statistically significant, that higher total doses increased the complication rate, that lower fraction sizes reduced the complication rate, and that longer overall radiotherapy treatment times were associated with higher complication rates. There was no association between the incidence of complications and the time interval between the end of radiotherapy and surgery.
Carcinoma, Squamous Cell↗
Stage T3 squamous cell carcinoma of the glottic larynx: a comparison of laryngectomy and irradiation.
One-hundred eighteen patients with previously untreated T3 squamous cell carcinoma of the glottic larynx were treated with curative intent between March 1965 and November 1988 at the University of Florida. All patients were observed for at least 2 years and 83% were observed for 5 or more years. Fifty-three patients were treated with irradiation alone and 65 patients were treated with surgery alone (32) or combined with irradiation (33). Thirty-two patients treated with irradiation alone had twice-daily fractionation and the remainder had once-daily fractionation. The local-regional control rates, including patients successfully salvaged after a local-regional recurrence, were 81% after irradiation alone and 81% after surgery alone or combined with adjuvant irradiation. The local control rates for patients treated with irradiation alone were 53% after once-daily fractionation and 71% after twice-daily fractionation. There was no relationship between vocal cord mobility at 5000 cGy, at the end of radiotherapy, or at 1 month after treatment and subsequent local control. The 5-year cause-specific survival rates were 74% for patients treated with irradiation alone and 63% for patients treated surgically. The incidence of severe complications, including those associated with salvage procedures, was 15% for both treatment groups. The rates of laryngeal voice preservation were 66% after irradiation alone and 2% after surgery. Irradiation alone for selected patients with T3 glottic cancer resulted in similar rates of local-regional control, survival, and severe complications, with a significantly higher likelihood of voice preservation, compared with surgery.
Carcinoma, Squamous Cell↗
Does neck stage influence local control in squamous cell carcinomas of the head and neck?
Recently, reports have suggested that the probability of local control of head and neck cancers treated with radiotherapy alone is inversely related to the extent of neck node disease at presentation. This has led some to conclude that primary lesions in patients with neck node metastases should be treated more aggressively than lesions of the same T stage in patients presenting with a clinically negative neck. We reviewed the records of 607 patients with squamous cell carcinoma of the head and neck to determine the relationship between the extent of neck node disease at diagnosis and the probability of tumor control at the primary site. All patients were treated with continuous-course irradiation alone to the primary site and have a minimum follow-up of 2 years. Mucosal sites analyzed included the oropharynx (soft palate, tonsillar region, base of tongue), hypopharynx (pharyngeal wall, pyriform sinus), and supraglottic larynx. Patients with simultaneous primary lesions were excluded from the analysis. Parameters tested included T stage, N stage, and fractionation (once daily or twice daily). For statistical analyses, N stage was grouped as N0, N1, N2A-N3A, and N2B-N3B. Local control was analyzed using a multivariate analysis, the forward stepwise long-rank test of association of covariates. Multivariate analyses revealed that the following parameters significantly influenced local control: oropharynx, T stage only (p = .0010); hypopharynx, T stage (p = .001) and twice-daily fractionation (p = .0031); and supraglottic larynx, T stage only (p = .0002). No significant correlation was found between neck stage and primary tumor control on univariate or multivariate analyses. Our data do not support the conclusion that primary lesions are controlled less often in patients with clinically positive neck nodes.
Carcinoma, Squamous Cell↗
Radiation therapy for skin cancer near the eye: kilovoltage x-rays versus electrons.
When skin cancer near the eye is irradiated, a corneal shield is placed between the lids and globe to protect ocular structures. The effectiveness of the shield was evaluated with 250 kVp x-ray and 6-20 MeV electron beams. To simulate the clinical situation, a face phantom was constructed out of solid pieces of water-equivalent epoxy. In the region of the eye the phantom was milled to the exact contour of a human face. The phantom was used to reconstruct the setup that had been used to treat a patient with a 1-cm basal cell carcinoma of the mid portion of the lower lid. A medium-sized corneal shield (2-mm-thick lead plated with 0.1 mm gold) was placed on the eye portion of the phantom. A contoured lead (6 mm thick) face mask was placed on the surface of the phantom to define a 3-cm diameter radiation field that included only the inferior hemisphere of the shield. The doses that the cornea, lens, and retina would receive beneath the midpoint of the inferior hemisphere of the shield were measured using thermoluminescent and film dosimetry. With 6 to 8 MeV electrons, the corneal dose was 2 to 4 times higher than with 250 kVp x-rays. Corneal and lens doses rose rapidly with increasing electron beam energy such that with greater than 8 MeV the shield would provide relatively poor ocular protection. A scanning ion chamber and film dosimetry were used to determine the isodose profiles of 250 kVp x-ray and 6 MeV electron beams for a 3-cm diameter field collimated on the surface. With 250 kVp x-rays the 95% isodose area was 32% wider than with 6 MeV electrons. The ease of shielding and the ability to minimize field size argue in favor of kilovoltage x-rays for early-stage skin cancer near the eye.
Costs and Cost Analysis↗
Unknown primary squamous cell carcinoma of the head and neck: is mucosal irradiation necessary?
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Carcinoma, Squamous Cell↗
Management of T1 and T2 squamous cell carcinoma of the glottic larynx.
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Carcinoma, Squamous Cell↗
Integrin-dependent phosphorylation and activation of the protein tyrosine kinase pp125FAK in platelets.
We have investigated mechanisms involved in integrin-mediated signal transduction in platelets by examining integrin-dependent phosphorylation and activation of a newly identified protein tyrosine kinase, pp125FAK (FAK, focal adhesion kinase). This kinase was previously shown to be localized in focal adhesions in fibroblasts, and to be phosphorylated on tyrosine in normal and Src-transformed fibroblasts. We show that thrombin and collagen activation of platelets causes an induction of tyrosine phosphorylation of pp125FAK and that pp125FAK molecules isolated from activated platelets display enhanced levels of phosphorylation in immune-complex kinase assays. pp125FAK was not phosphorylated on tyrosine after thrombin or collagen treatment of Glanzmann's thrombasthenic platelets deficient in the fibrinogen receptor GPIIb-IIIa, or of platelets pretreated with an inhibitory monoclonal antibody to GP IIb-IIIa. Fibrinogen binding to GP IIb-IIIa was not sufficient to induce pp125FAK phosphorylation because pp125FAK was not phosphorylated on tyrosine in thrombin-treated platelets that were not allowed to aggregate. These results indicate that tyrosine phosphorylation of pp125FAK is dependent on platelet aggregation mediated by fibrinogen binding to the integrin receptor GP IIb-IIIa. The induction of tyrosine phosphorylation of pp125FAK was inhibited in thrombin- and collagen-treated platelets preincubated with cytochalasin D, which prevents actin polymerization following activation. Under all of these conditions, there was a strong correlation between the induction of tyrosine phosphorylation of pp125FAK in vivo and stimulation of the phosphorylation of pp125FAK in vitro in immune-complex kinase assays. This study provides the first genetic evidence that tyrosine phosphorylation of pp125FAK is dependent on integrin-mediated events, and demonstrates that there is a strong correlation between tyrosine phosphorylation of pp125FAK in platelets, and the activation of pp125FAK-associated phosphorylating activity in vitro.
Blood Platelets↗
Mutations within the 5' half of the avian retrovirus MC29 v-myc gene alter or abolish transformation of chicken embryo fibroblasts and macrophages.
Avian myelocytomatosis virus MC29 induces a wide variety of neoplastic diseases in infected birds and transforms cells of the macrophage lineage as well as fibroblasts and epithelial cells. A biological and biochemical analysis, carried out on a series of in-frame insertion and deletion mutations within the gag-myc gene of MC29, revealed several mutations within the 5' portion of the v-myc gene that encode proteins either completely defective for transformation or compromised in their ability to transform chicken embryo fibroblasts but not macrophages. Mutations within the 3' end of the v-myc gene which disrupt sequences encoding the basic/helix-loop-helix region were defective for transformation of both fibroblasts and macrophages. Eight variants were cloned into the replication-competent avian expression vector RCAS. Analysis of cells infected with transformation-defective, replication-competent viruses confirmed the expression of functionally defective Myc proteins. Further, expression of the transformation defective variant dl91-137 in chicken fibroblasts inhibited subsequent transformation by wild-type MC29. The results reported herein support the hypothesis that Myc proteins function as regulators of transcription in a variety of cell types and clearly point out the necessity of putative regulatory domains within the amino-terminal half of the Myc protein.
Animals↗
Mandibular lingual releasing approach.
The mandibular lingual releasing approach to oral cavity and oropharyngeal tumors provides excellent visualization for resection while integrity of the mandibular arch is preserved. A lingual floor-of-mouth flap is created, which allows delivery of these structures directly into the neck without lip splitting, mandibulotomy, or mandibulectomy. The procedure was carried out on 15 patients between 1987 and 1991, with followup ranging from 2 to 50 months. Nine patients had received previous radiation, whereas planned postoperative radiation was administered to five patients. The visualization afforded by this technique was very good, in that 12 patients had clear margins of resection. Three patients had close margins; recurrent disease developed in one of these patients 18 months later. Twelve of the patients were able to maintain their weight with an oral diet alone. Four postoperative fistulae occurred, three of these were in patients who had not been previously irradiated. The single fistula that did not spontaneously heal occurred in a patient who had received previous radiation and was also on long-term corticosteroids. Mandibular osteoradionecrosis developed in two patients who received postoperative radiation. The complication rate after previous radiation is acceptable; however, there is risk of mandibular osteoradionecrosis after high-dose postoperative radiation.
Adult↗
Identification and characterization of a cytoskeleton-associated, epidermal growth factor sensitive pp60c-src substrate.
In studies aimed at identifying and characterizing pp60c-src substrates that participate in the enhanced mitogenic response to epidermal growth factor (EGF) observed in murine C3H10T1/2 fibroblasts overexpressing c-src, we have identified a 75-kDa protein (p75) whose properties are consistent with those expected of such a substrate. We present evidence to show that p75 is immunologically related to a recently described, cytoskeleton-associated, pp60v-src substrate [Wu et al. (1991). Mol. Cell. Biol., 11, 5113-5124), and that its phosphotyrosine content is increased cooperatively by c-src overexpression and EGF stimulation. p75 is rapidly (within 2 min) phosphorylated on tyrosine upon EGF treatment and undergoes a second, prolonged phase of tyrosyl phosphorylation from 7 to 21 h after EGF addition, suggesting that tyrosyl phosphorylation of p75 is important for late as well as early events following EGF receptor activation. Enhanced tyrosyl phosphorylation of p75 is also seen when cells overexpressing c-src are treated with platelet-derived growth factor (PDGF), but significantly less phosphorylation is observed with insulin and fibroblast growth factor (FGF). Both basal and EGF-induced tyrosyl phosphorylation of p75 are reduced in cells overexpressing mutated forms of c-src (unmyristylated, or kinase deficient) as compared with wild-type c-src overexpressers, indicating the dependence of the enhanced tyrosyl phosphorylation on membrane-associated, enzymatically active pp60c-src. In cellular fractionation experiments p75 partitions with the cytosol, while immunofluorescence studies reveal a striking colocalization with pp60c-src at the plasma membrane and in the perinuclear region. Partial co-staining of p75 and actin occurs at the cell's periphery. These data provide evidence for p75 being a direct substrate of pp60c-src. The possible role of p75 in the enhanced response to EGF seen in c-src overexpressers is discussed.
Animals↗
Tyrosine phosphorylation of a 120,000 dalton membrane-associated protein by the neural form of pp60c-src, pp60c-src+.
The c-src proto-oncogene encodes a 60,000 dalton tyrosine kinase, pp60c-src, which is the prototype member of the family of non-receptor tyrosine kinases. A neural-specific form of pp60c-src, pp60c-src+, is detected only in neurons of the central nervous system. pp60c-src+ contains a six amino acid insert (neural insert) in the SH3 region that is generated by alternative splicing. Previous reports indicate that the profiles of proteins phosphorylated on tyrosine in chick embryo fibroblast (CEF) cells by pp60c-src+ or pp60c-src are equivalent. In this report, the activities of pp60c-src+ and pp60c-src, as well as the activated variants, pp60(527F+) and pp60(527F), were compared in CEF cells by examining the steady-state levels of tyrosine phosphorylation of several known pp60src substrates. Most substrates examined were phosphorylated on tyrosine to equivalent levels in CEF cells expressing either the neural- or fibroblast-specific src gene products. However, the relative extent of tyrosine phosphorylation of a 120 kDa protein (p120) was increased in cells expressing the neuronal forms of either c-src or c-src527F. The increased tyrosine phosphorylation of p120 did not appear to be caused by the neural insert facilitating a specific interaction between pp60c-src+ and p120. These data indicate that preferential phosphorylation of p120 in neural cells may contribute to the specialized function of pp60c-src+ in neural cells.
Animals↗
The SH2 and SH3 domains of pp60src direct stable association with tyrosine phosphorylated proteins p130 and p110.
Transformation of chicken embryo cells with the tyrosine kinase oncogene src results in the tyrosine phosphorylation of numerous cellular proteins. We have recently generated monoclonal antibodies to individual tyrosine phosphorylated cellular src substrates, several of which are directed to the phosphotyrosine-containing proteins p130 and p110. These proteins form stable complexes with activated variants of pp60src. Mutagenesis of the src homology domains (SH2 and SH3) of activated pp60src resulted in src variants with altered association with p130 and p110. Analysis of these variants showed that the SH3 domain was required for association of p110, while the SH2 domain contained residues necessary for the formation of the ternary complex involving p130, p110 and pp60src. Both the tyrosine phosphorylation status and pp60src association of p130 and p110 appeared to correlate, in part, with the extent of cell transformation. Biochemical analysis demonstrated that p130 and p110 were substrates of both serine/threonine and tyrosine kinases. In addition, p130 was redistributed from the nucleus to cellular membranes upon src transformation, whereas p110, which normally colocalized with cytoskeletal elements, was observed in adhesion plaques (podosomes) in src transformed cells. These data indicate that tyrosine phosphorylation of two different phosphoproteins may play a role during src transformation either by directing their interaction with pp60src, by redirecting subcellular distribution or both.
Animals↗
Tyrosine phosphorylation of three cellular proteins correlates with transformation of rat 1 cells by pp60src.
The analysis of phosphotyrosine-containing proteins in Rat 1 cells overexpressing either the tyrosine kinase pp60c-src or genetic variants containing alterations in functional and structural domains has led to the identification of three proteins whose tyrosine phosphorylation correlated with pp60src-induced cellular transformation. The tyrosine phosphorylation of one of these proteins, p120, has been previously shown by us and others to coincide with the presence of kinase-activated, membrane-associated pp60src in chicken embryo cells. The second protein was identified as the ras-associated GTPase-activating protein (GAP). The third protein whose tyrosine phosphorylation was markedly elevated in Rat 1 cells expressing activated, membrane-bound forms of pp60src had an apparent molecular mass of 64-67 kDa. The electrophoretic mobility of this protein varied in cells expressing different pp60src variants. The tyrosine-phosphorylated form of p64-67 was present in immune complexes containing GAP, suggesting a stable interaction between these two cellular proteins.
Animals↗
The role of radiation therapy in inverted papilloma of the nasal cavity and paranasal sinuses.
Between December 1969 and March 1985, seven patients with advanced biologically aggressive inverted or cylindrical cell papillomas were treated with irradiation at the University of Florida. Three patients were treated with radiation therapy alone, and four patients were irradiated either before (one patient) or after (three patients) resection. No recurrences were observed in six patients at 4.5, 7, 8, 8, 9, and 20 years following treatment (including two who died of intercurrent disease at 7 and 9 years after radiation therapy without evidence of recurrent tumor). One patient treated with irradiation alone for an advanced recurrent papilloma developed a local recurrence extending into the frontal lobe of the brain and died 17 months after radiation therapy. None of the patients experienced a significant complication of irradiation. Although surgery is generally the primary treatment modality for this disease, radiation therapy should be considered for patients with advanced, incompletely resected, or unresectable lesions.
Adult↗
Primary subglottic cancer: results of radical radiation therapy.
Between October 1964 and December 1985, six patients with primary squamous cell carcinoma of the subglottis were treated with radical radiation therapy at the University of Florida. The disease was staged as Tis (one patient), T2N0 (two patients), and T4N0 (three patients). Local control was achieved with irradiation in four patients (66%) who were observed for 3.5, 4, 4, and 5 years after radiation therapy. Two patients whose tumors recurred at the primary site underwent salvage laryngectomy, which was successful in one patient.
Aged↗