Dominant negative mutations in human PPARgamma associated with severe insulin resistance, diabetes mellitus and hypertension

Thiazolidinediones are a new class of antidiabetic agent that improve insulin sensitivity and reduce plasma glucose and blood pressure in subjects with type 2 diabetes. Although these agents can bind and activate an orphan nuclear receptor, peroxisome proliferator-activated receptor gamma (PPARgamma), there is no direct evidence to conclusively implicate this receptor in the regulation of mammalian glucose homeostasis. Here we report two different heterozygous mutations in the ligand-binding domain of PPARgamma in three subjects with severe insulin resistance. In the PPARgamma crystal structure, the mutations destabilize helix 12 which mediates transactivation. Consistent with this, both receptor mutants are markedly transcriptionally impaired and, moreover, are able to inhibit the action of coexpressed wild-type PPARgamma in a dominant negative manner. In addition to insulin resistance, all three subjects developed type 2 diabetes mellitus and hypertension at an unusually early age. Our findings represent the first germline loss-of-function mutations in PPARgamma and provide compelling genetic evidence that this receptor is important in the control of insulin sensitivity, glucose homeostasis and blood pressure in man.

Divergence of melanocortin pathways in the control of food intake and energy expenditure

Activation of melanocortin-4-receptors (MC4Rs) reduces body fat stores by decreasing food intake and increasing energy expenditure. MC4Rs are expressed in multiple CNS sites, any number of which could mediate these effects. To identify the functionally relevant sites of MC4R expression, we generated a loxP-modified, null Mc4r allele (loxTB Mc4r) that can be reactivated by Cre-recombinase. Mice homozygous for the loxTB Mc4r allele do not express MC4Rs and are markedly obese. Restoration of MC4R expression in the paraventricular hypothalamus (PVH) and a subpopulation of amygdala neurons, using Sim1-Cre transgenic mice, prevented 60% of the obesity. Of note, increased food intake, typical of Mc4r null mice, was completely rescued while reduced energy expenditure was unaffected. These findings demonstrate that MC4Rs in the PVH and/or the amygdala control food intake but that MC4Rs elsewhere control energy expenditure. Disassociation of food intake and energy expenditure reveals unexpected divergence in melanocortin pathways controlling energy balance.

Profiling membrane lipids in plant stress responses. Role of phospholipase D alpha in freezing-induced lipid changes in Arabidopsis

A sensitive approach based on electrospray ionization tandem mass spectrometry has been employed to profile membrane lipid molecular species in Arabidopsis undergoing cold and freezing stresses. Freezing at a sublethal temperature induced a decline in many molecular species of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) but induced an increase in phosphatidic acid (PA) and lysophospholipids. To probe the metabolic steps generating these changes, lipids of Arabidopsis deficient in the most abundant phospholipase D, PLD alpha, were analyzed. The PC content dropped only half as much, and PA levels rose only half as high in the PLD alpha-deficient plants as in wild-type plants. In contrast, neither PE nor PG levels decreased significantly more in wild-type plants than in PLD alpha-deficient plants. These data suggest that PC, rather than PE and PG, is the major in vivo substrate of PLD alpha. The action of PLD alpha during freezing is of special interest because Arabidopsis plants that are deficient in PLD alpha have improved tolerance to freezing. The greater loss of PC and increase in PA in wild-type plants as compared with PLD alpha-deficient plants may be responsible for destabilizing membrane bilayer structure, resulting in a greater propensity toward membrane fusion and cell death in wild-type plants.

Mice lacking ghrelin receptors resist the development of diet-induced obesity

Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHSR; ghrelin receptor). Since its discovery, accumulating evidence has suggested that ghrelin may play a role in signaling and reversing states of energy insufficiency. For example, ghrelin levels rise following food deprivation, and ghrelin administration stimulates feeding and increases body weight and adiposity. However, recent loss-of-function studies have raised questions regarding the physiological significance of ghrelin in regulating these processes. Here, we present results of a study using a novel GHSR-null mouse model, in which ghrelin administration fails to acutely stimulate food intake or activate arcuate nucleus neurons. We show that when fed a high-fat diet, both female and male GHSR-null mice eat less food, store less of their consumed calories, preferentially utilize fat as an energy substrate, and accumulate less body weight and adiposity than control mice. Similar effects on body weight and adiposity were also observed in female, but not male, GHSR-null mice fed standard chow. GHSR deletion also affected locomotor activity and levels of glycemia. These findings support the hypothesis that ghrelin-responsive pathways are an important component of coordinated body weight control. Moreover, our data suggest that ghrelin signaling is required for development of the full phenotype of diet-induced obesity.

Cloning and expression of AP-2, a cell-type-specific transcription factor that activates inducible enhancer elements

Human AP-2 is a sequence-specific DNA-binding protein that interacts with inducible viral and cellular enhancer elements to stimulate transcription of selected genes. Here, we report the isolation and characterization of a human cDNA clone containing the entire protein-coding region of AP-2. The deduced primary amino acid sequence of AP-2 does not contain a domain resembling any previously identified DNA binding motif. However, an interesting feature of the AP-2 protein is a clustered arrangement of proline and glutamine residues that have been found recently within the activation domains of other transcription factors. Expression of the AP-2 clone in bacteria yields a protein that binds to DNA and activates transcription in vitro in a comparable manner to native human AP-2. Transfection of cDNA clones into Drosophila cells indicates that the AP-2 gene product can also activate gene expression in vivo in a DNA template-dependent manner. Expression of endogenous AP-2 is repressed in a hepatoma cell line and stimulated following retinoic-acid-induced differentiation of a human teratocarcinoma cell line. This indicates that AP-2 may be a transcription factor involved in the control of developmentally regulated gene expression.

Neural tube, skeletal and body wall defects in mice lacking transcription factor AP-2

The retinoic acid-inducible transcription factor AP-2 is expressed in epithelial and neural crest cell lineages during murine development. AP-2 can regulate neural and epithelial gene transcription, and is associated with overexpression of c-erbB-2 in human breast-cancer cell lines. To ascertain the importance of AP-2 for normal development, we have derived mice containing a homozygous disruption of the AP-2 gene. These AP-2-null mice have multiple congenital defects and die at birth. In particular, the AP-2 knockout mice exhibit anencephaly, craniofacial defects and thoraco-abdominoschisis. Skeletal defects occur in the head and trunk region, where many bones are deformed or absent. Analysis of these mice earlier in embryogenesis indicates a failure of cranial neural-tube closure and defects in cranial ganglia development. We have shown that AP-2 is a fundamental regulator of mammalian craniofacial development.

A Phase II Study of Pembrolizumab in EGFR-Mutant, PD-L1+, Tyrosine Kinase Inhibitor Naïve Patients With Advanced NSCLC

BACKGROUND

Despite the significant antitumor activity of pembrolizumab in NSCLC, clinical benefit has been less frequently observed in patients whose tumors harbor EGFR mutations compared to EGFR wild-type patients. Our single-center experience on the KEYNOTE-001 trial suggested that pembrolizumab-treated EGFR-mutant patients, who were tyrosine kinase inhibitor (TKI) naïve, had superior clinical outcomes to those previously treated with a TKI. As TKI naïve EGFR-mutants have generally been excluded from pembrolizumab studies, data to guide treatment decisions in this patient population is lacking, particularly in patients with programmed death ligand 1 (PD-L1) expression ≥50%.

METHODS

We conducted a phase II trial (NCT02879994) of pembrolizumab in TKI naive patients with EGFR mutation-positive, advanced NSCLC and PD-L1-positive (≥1%, 22C3 antibody) tumors. Pembrolizumab was administered 200 mg every 3 weeks. The primary endpoint was objective response rate. Secondary endpoints included safety of pembrolizumab, additional pembrolizumab efficacy endpoints, and efficacy and safety of an EGFR TKI after pembrolizumab.

RESULTS

Enrollment was ceased due to lack of efficacy after 11 of 25 planned patients were treated. Eighty-two percent of trial patients were treatment naïve, 64% had sensitizing EGFR mutations, and 73% had PD-L1 expression ≥50%. Only 1 patient had an objective response (9%), but repeat analysis of this patient's tumor definitively showed the original report of an EGFR mutation to be erroneous. Observed treatment-related adverse events were similar to prior experience with pembrolizumab, but two deaths within 6 months of enrollment, including one attributed to pneumonitis, were of concern.

CONCLUSIONS

Pembrolizumab's lack of efficacy in TKI naïve, PD-L1+, EGFR-mutant patients with advanced NSCLC, including those with PD-L1 expression ≥50%, suggests that it is not an appropriate therapeutic choice in this setting.

Analysis of the DNA-binding and activation properties of the human transcription factor AP-2

The mammalian transcription factor AP-2 is a sequence-specific DNA-binding protein expressed in neural crest lineages and regulated by retinoic acid. Here we report a structure/function analysis of the DNA-binding and transcription activation properties of the AP-2 protein. DNA contact studies indicate that AP-2 binds as a dimer to a palindromic recognition sequence. Furthermore, cross-linking and immunoprecipitation data illustrate that AP-2 exists as a dimer even in the absence of DNA. Examination of cDNA mutants reveals that the sequences responsible for DNA binding are located in the carboxy-terminal half of the protein. In addition, a domain mediating dimerization forms an integral component of this DNA-binding structure. Expression of AP-2 in mammalian cells demonstrates that transcriptional activation requires an additional amino-terminal domain that contains an unusually high concentration of proline residues. This proline-rich activation domain also functions when attached to the heterologous DNA-binding region of the GAL4 protein. This study reveals that although AP-2 shares an underlying modular organization with other transcription factors, the regions of AP-2 involved in transcriptional activation and DNA binding/dimerization have novel sequence characteristics.

Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness

1. There is little unequivocal evidence to date in support of a positive relationship between egg size and offspring fitness in birds. Although 40 studies (of 34 species) have considered the effect of variation in egg size on chick growth and/or survival up to fledgling only 12 studies have controlled for other characters potentially correlated both with egg size and offspring fitness. Of these only two have reported a significant residual effect of egg size on chick growth (in the roseate tern and European blackbird) and three a residual effect on chick survival (all in seabirds: common tern, lesser black-backed gull and kittiwake). 2. More consistent evidence exists, though from fewer studies, for a positive relationship between egg size and offspring fitness early in the chick-rearing period; chick growth and chick survival being dependent on egg size in 8 of 10 studies and 4 of 5 studies respectively. It is suggested that the most important effect of variation in egg size might be in determining the probability of offspring survival in the first few days after hatching. 3. Egg size explains on average 66% of the variation in chick mass at hatching (n = 35 studies) but only 30% of the variation in chick body size (n = 18). When effects of hatching body size are controlled for chick mass remains significantly correlated with egg size, though the reverse is not true. This supports the hypothesis that large eggs give rise to heavier chicks at hatching, i.e., chicks with more nutrient (yolk) reserves, rather than structurally larger chicks. 4. Egg composition increased isometrically with increasing egg size in about half the studies so far reported (n equals approximately 20). However, in seabirds, and some passerines, larger eggs contain disproportionately more albumen, whilst in some waterfowl percentage yolk content increases with increasing egg size. Changes in albumen content largely reflect variation in the water content of eggs, but changes in yolk content involve variation in lipid content, and therefore in egg 'quality.' The adaptive significance of variation in egg composition is considered; females may adjust egg composition facultatively to maximise the benefits to their offspring of increased reproductive investment. 5. Considerations for future research are discussed with particular emphasis on experimental studies and the application of new techniques.

Impaired growth hormone responses to growth hormone-releasing factor in obesity. A pituitary defect reversed with weight reduction

To investigate whether the impaired growth hormone secretion associated with obesity is a result of a hypothalamic or a pituitary disorder and whether it is a cause or a consequence of obesity, we studied plasma growth hormone responses to growth hormone-releasing factor in morbidly obese patients before gastrointestinal surgical therapy, in formerly obese subjects who had lost considerable weight postoperatively, and in non-obese controls. Growth hormone secretion was also assessed in response to insulin-induced hypoglycemia (in seven patients preoperatively and four postoperatively). In patients studied preoperatively, growth hormone responses to growth hormone-releasing factor were markedly impaired (P less than 0.001 as compared with controls), whereas in patients studied postoperatively they were partially restored to normal (P less than 0.05 as compared with those studied preoperatively). Growth hormone responses to insulin-induced hypoglycemia were similarly diminished in obese patients studied before operation (P less than 0.02). The growth hormone response to growth hormone-releasing factor was inversely correlated with the percentage of ideal body weight (P less than 0.01) and directly correlated with the growth hormone response to insulin (P less than 0.01). The impaired responsiveness to growth hormone-releasing factor suggests that the diminished response to insulin hypoglycemia is mediated by an impaired pituitary response to endogenous growth hormone-releasing factor. The reversibility of the defect after weight reduction suggests that it is a consequence rather than a cause of obesity.

Activation and adoptive transfer of Epstein-Barr virus-specific cytotoxic T cells in solid organ transplant patients with posttransplant lymphoproliferative disease

The treatment of Epstein-Barr virus (EBV)-associated lymphoproliferative disease (PTLD) in EBV seronegative solid organ transplant recipients who acquire their EBV infection after engraftment poses a considerable challenge because of underlying immunosuppression that inhibits the virus-specific cytotoxic T cell (CTL) response in vivo. We have developed a protocol for activating autologous EBV-specific CTL lines from these patients and show their potential use for immunotherapy against PTLD in solid organ transplant patients. Peripheral blood mononuclear cells from a panel of solid organ transplant recipients with and without active PTLD were used to assess EBV-specific memory CTL responses. The activation protocol involved cocultivation of peripheral blood mononuclear cells with an autologous lymphoblastoid cell line under conditions that favored expansion of virus-specific CTL and hindered the proliferation of allospecific T cells. These CTL consistently showed (i) strong EBV-specificity, including reactivity through defined epitopes in spite of concurrent immunosuppressive therapy, and (ii) no alloreactivity toward donor alloantigens. More importantly, adoptive transfer of these autologous CTLs into a single patient with active PTLD was coincident with a very significant regression of the PTLD. These results demonstrate that a potent EBV-specific memory response can be expanded from solid organ recipients who have acquired their primary EBV infection under high levels of immunosuppressive therapy and that these T cells may have therapeutic potential against PTLD.

Randomized trial of allopurinol in the prevention of calcium oxalate calculi

In a double-blind study, we examined the efficacy of allopurinol in the prevention of recurrent calcium oxalate calculi of the kidney. Sixty patients with hyperuricosuria and normocalciuria who had a history of calculi were randomly assigned to receive either allopurinol (100 mg three times daily) or a placebo. After the study, the placebo group had 63.4 percent fewer calculi (P less than 0.001), whereas the allopurinol group had 81.2 percent fewer calculi (P less than 0.001). During the study period, the mean rate of calculous events was 0.26 per patient per year in the placebo group and 0.12 in the allopurinol group. When the treatment groups were compared by actuarial analysis, the allopurinol group was found to have a significantly longer time before recurrence of calculi (P less than 0.02). We conclude that allopurinol is effective in the prevention of calcium oxalate stones in patients with hyperuricosuria. The large reduction in the frequency of calculi in the placebo group underscores the positive treatment bias that regularly occurs in trials of prophylaxis against renal calculi when historical controls are used.

Time-varying magnetic fields: effect on DNA synthesis

Human fibroblasts have exhibited enhanced DNA synthesis when exposed to sinusoidally varying magnetic fields for a wide range of frequencies (15 hertz to 4 kilohertz) and amplitudes (2.3 X 10(-6) to 5.6 X 10(-4) tesla). This effect, which is at maximum during the middle of the S phase of the cell cycle, appears to be independent of the time derivative of the magnetic field, suggesting an underlying mechanism other than Faraday's law. The threshold is estimated to be between 0.5 X 10(-5) and 2.5 X 10(-5) tesla per second. These results bring into question the allegedly specific magnetic wave shapes now used in therapeutic devices for bone nonunion. The range of magnetic field amplitudes tested encompass the geomagnetic field, suggesting the possibility of mutagenic interactions directly arising from short-term changes in the earth's field.

Reproductive effects of long-term exposure to Bisphenol A in the fathead minnow (Pimephales promelas)

Bisphenol A (BPA), a high-volume chemical used to make polycarbonate plastic, epoxy resins, and other chemicals has been reported to be weakly estrogenic. To investigate the effects of long-term exposure to Bisphenol A, a multigeneration study was conducted in which fathead minnows (Pimephales promelas) were exposed to water concentrations of BPA in the range from 1 to 1280 micrograms/L. In this paper, we report the growth and reproductive effects of BPA on sexually mature adults in the F0 generation (after 43, 71, and 164 d of exposure) and the effects on hatchability in the F1 generation. Mean measured concentrations of BPA in the water for all doses, over a 164-d exposure period, were between 70% and 96% of nominal. An inhibitory effect of BPA on somatic growth (length and weight) occurred in adult male fish exposed to 640 and 1280 micrograms/L (after 71 and 164 d). BPA induced vitellogenin synthesis (VTG; a biomarker for estrogen exposure) in males at concentrations of 640 and 1280 micrograms/L after 43 d and 160 micrograms/L after 71 d. In females, plasma VTG concentrations were elevated above controls only after 164-d exposure to 640 micrograms/L. Inhibition of gonadal growth (as measured by the gonadosomatic index) occurred in both males and females at concentrations of 640 and 1280 micrograms/L after 164 d. In males, a concentration of 16 micrograms/L altered the proportion of sex cell types in the testis, suggesting inhibition of spermatogenesis. Concentrations of BPA that induced VTG synthesis and affected gonadal development were lower than those that resulted in discernible effects on reproductive output. Egg production was inhibited at a BPA concentration of 1280 micrograms/L, and hatchability in the F1 generation was reduced at a BPA concentration of 640 micrograms/L (there were not enough eggs spawned in the 1280 micrograms/L group for hatchability studies to be conducted). The results demonstrate that BPA acts as a weak estrogen to fish when administered via the water, with effects on breeding at and above 640 micrograms/L.

Clinical information for research; the use of general practice databases

General practice computers have been widely used in the United Kingdom for the last 10 years and there are over 30 different systems currently available. The commercially available databases are based on two of the most widely used systems--VAMP Medical and Meditel. These databases provide both longitudinal and cross-sectional data on between 1.8 and 4 million patients. Despite their availability only limited use has been made of them for epidemiological and health service research purposes. They are a unique source of population-based information and deserve to be better recognized. The advantages of general practice databases include the fact that they are population based with excellent prescribing data linked to diagnosis, age and gender. The problems are that their primary purpose is patient care and the database population is constantly changing, as well as the usual problems of bias and confounding that occur in any observational studies. The barriers to the use of general practice databases include the cost of access, the size of the databases and that they are not structured in a way that easily allows analysis. Proper utilization of these databases requires powerful computers, staff proficient in writing computer programs to facilitate analysis and epidemiologists skilled in their use. If these structural problems are overcome then the databases are an invaluable source of data for epidemiological studies.

Regulation of transcription factor AP-2 by the morphogen retinoic acid and by second messengers

The expression of the transcription factor AP-2 recently has been shown to be enhanced during retinoic acid (RA)-induced differentiation of NT2 cells, a human teratocarcinoma cell line. Here we show that this induction of AP-2 mRNA is at the level of transcription and is transient, reaching a peak 48-72 hr after the addition of RA and declining thereafter, even in the continuous presence of RA. Increased levels of AP-2 mRNA are reflected in a similar elevation of AP-2 protein and accompanied by an increase in the AP-2-binding site-dependent transcriptional activity of a reporter gene. AP-2 also has been proposed to confer TPA and cAMP inducibility on promoters/enhancers containing AP-2-binding sites. We investigated the effect of these agents on the expression of AP-2 protein and mRNA. Our experiments demonstrate that expression of the AP-2 gene in HeLa cells is not elevated significantly by TPA or by a calcium ionophore and is not enhanced at all by agents that increase intracellular cAMP concentration. In fact, AP-2 mRNA is repressed by both TPA and the calcium ionophore A23187 through a delayed response. These data suggest that the AP-2-binding site-mediated cAMP and TPA responses are not regulated at the level of AP-2 expression but, rather, achieved either by post-translational changes in AP-2 or in conjunction with another protein.

Migratory movements, depth preferences, and thermal biology of Atlantic bluefin tuna

The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of >1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic.

Peroxynitrite modification of protein thiols: oxidation, nitrosylation, and S-glutathiolation of functionally important cysteine residue(s) in the sarcoplasmic reticulum Ca-ATPase

Skeletal muscle contraction and relaxation is efficiently modulated through the reaction of reactive oxygen-nitrogen species with sarcoplasmic reticulum protein thiols in vivo. However, the exact locations of functionally important modifications are at present unknown. Here, we determine by HPLC-MS that the modification of one (out of 24) Cys residue of the sarcoplasmic reticulum (SR) Ca-ATPase isoform SERCA1, Cys(349), by peroxynitrite is sufficient for the modulation of enzyme activity. Despite the size and nature of the SR Ca-ATPase, a 110 kDa membrane protein, identification and quantitation of Cys modification was achieved through labeling with 4-(dimethylamino)phenylazophenyl-4'-maleimide (DABMI) and/or N-(2-iodoethyl)trifluoroacetamide (IE-TFA) followed by an exhaustive tryptic digestion and on-line HPLC-UV-electrospray MS analysis. The reaction with IE-TFA generates aminoethylcysteine, a new trypsin cleavage site, which allows the production of specific peptide fragments that are diagnostic for IE-TFA labeling, conveniently identified by mass spectrometry. Exposure of the SR Ca-ATPase to low concentrations (0.1 mM) of peroxynitrite resulted in the fully reversible chemical modification of Cys at positions 344, 349, 471, 498, 525, and 614 (nitrosylation of Cys(344) and Cys(349) was seen), whereas higher concentrations of peroxynitrite (0.45 mM) additionally affected Cys residues at positions 636, 670, and 674. When the SR Ca-ATPase was exposed to 0.45 mM peroxynitrite in the presence of 5.0 mM glutathione (GSH), thiol modification became partially reversible and S-glutathiolation was detected for Cys residues at positions 344, 349, 364, 498, 525, and 614. The extent of enzyme inactivation (determined previously) quantitatively correlated with the loss of labeling efficiency (i) of a single Cys residue and (ii) of the tryptic fragment containing both Cys(344) and Cys(349). Earlier results had shown that the independent selective modification of Cys(344) is functionally insignificant [Kawakita, M., and Yamashita, T. (1987) J. Biochem. (Tokyo) 102, 103-109]. Thus, we conclude that modification of only Cys(349) is responsible for the modulation of the SR Ca-ATPase activity by peroxynitrite.

Management of invasive candidal infections: results of a prospective, randomized, multicenter study of fluconazole versus amphotericin B and review of the literature

We conducted a prospective, randomized, multicenter study comparing fluconazole and amphotericin B in the treatment of candidal infections. One hundred and sixty-four patients (60 of whom were neutropenic) with documented or presumed invasive candidiasis were assigned to treatment with either fluconazole (400 mg daily) or amphotericin B (25-50 mg daily; 0.67 mg/kg daily for neutropenic patients). Clinical response and survival rates were assessed at 48 hours, after 5 days, and at the end of therapy. Overall response rates to fluconazole and amphotericin B were similar (66% and 64%, respectively). There were no differences in response as related to site of infection, pathogen, time to defervescence, relapse, or survival rates between the groups. Adverse effects were more frequent with amphotericin B (35%) than with fluconazole (5%; P < .0001). The results of this study confirm that fluconazole is as effective as but better tolerated than amphotericin B in the treatment of candidal infections.

Glucagon-like peptide-1 receptor stimulation increases blood pressure and heart rate and activates autonomic regulatory neurons

Glucagon-like peptide-1 (GLP-1) released from the gut functions as an incretin that stimulates insulin secretion. GLP-1 is also a brain neuropeptide that controls feeding and drinking behavior and gastric emptying and elicits neuroendocrine responses including development of conditioned taste aversion. Although GLP-1 receptor (GLP-1R) agonists are under development for the treatment of diabetes, GLP-1 administration may increase blood pressure and heart rate in vivo. We report here that centrally and peripherally administered GLP-1R agonists dose-dependently increased blood pressure and heart rate. GLP-1R activation induced c-fos expression in the adrenal medulla and neurons in autonomic control sites in the rat brain, including medullary catecholamine neurons providing input to sympathetic preganglionic neurons. Furthermore, GLP-1R agonists rapidly activated tyrosine hydroxylase transcription in brainstem catecholamine neurons. These findings suggest that the central GLP-1 system represents a regulator of sympathetic outflow leading to downstream activation of cardiovascular responses in vivo.

Multiinstitutional phase II trial of paclitaxel, carboplatin, and concurrent radiation therapy for locally advanced non-small-cell lung cancer

PURPOSE

Combined modality therapy for non-small-cell lung cancer (NSCLC) has produced promising results. A multiinstitutional phase II clinical trial was conducted to evaluate the activity and toxicity of paclitaxel, carboplatin, and concurrent radiation therapy on patients with locally advanced NSCLC.

PATIENTS AND METHODS

Forty previously untreated patients with inoperable locally advanced NSCLC entered onto a phase II study from March 1995 to December 1996. On an outpatient basis for 7 weeks, patients received paclitaxel 50 mg/m2 weekly over 1 hour; carboplatin at (area under the curve) AUC 2 weekly; and radiation therapy of 66 Gy in 33 fractions. After chemoradiation therapy, patients received an additional two cycles of paclitaxel 200 mg/m2 over 3 hours and carboplatin at AUC 6 every 3 weeks.

RESULTS

Thirty-nine patients were eligible for the study. The survival rates at 12 months were 56.3%, and at 24 months, 38.3%, with a median overall survival of 20.5 months. The progression-free survival rates at 12 months were 43.6%, and at 24 months, 34.7%, with a median progression-free survival of 9.0 months. Two patients did not receive more than 2 weeks of concurrent chemoradiotherapy and were not assessable for toxicity and response. The overall response rate (partial plus complete response) of 37 assessable patients was 75.7%. The major toxicity was esophagitis. Seventeen patients (46%) developed grade 3 or 4 esophagitis. However, only two patients developed late esophageal toxicity with stricture at 3 and 6 months posttreatment.

CONCLUSION

Combined modality therapy with paclitaxel, carboplatin, and radiation is a promising treatment for locally advanced NSCLC that has a high response rate and acceptable toxicity and survival rates. A randomized trial will be necessary to fully evaluate the usefulness of these findings.

The developmentally regulated transcription factor AP-2 is involved in c-erbB-2 overexpression in human mammary carcinoma

Overexpression of the c-erbB-2/HER2 protooncogene in breast carcinoma is controlled not only by the degree of amplification of the gene but also at the level of gene transcription. Thus, whether or not the gene is amplified, the activity of the c-erbB-2 promoter is enhanced in overexpressing cells through the binding of an additional transcription factor, OB2-1, whose activity is increased in these lines. Here we describe further characterization of OB2-1 and show that it is identical to the developmentally regulated transcription factor AP-2. Functional assays confirm that AP-2 is able to regulate c-erbB-2 expression in mammary-derived cell lines. Furthermore, although AP-2 is barely detectable in cells with the low c-erbB-2 expression phenotype, protein levels are clearly elevated in a panel of c-erbB-2-overexpressing lines. These findings demonstrate an important role for this transcription factor in human cancer.

Characterization of a dimerization motif in AP-2 and its function in heterologous DNA-binding proteins

The mammalian transcription factor AP-2 is a retinoic acid inducible sequence-specific DNA-binding protein that is developmentally regulated. In this report, the functional domains necessary for AP-2 DNA binding were studied. AP-2 required a dimerization domain and an adjacent region of net basic charge to achieve a sequence-specific protein:DNA interaction. The sequences responsible for dimerization consisted of two putative amphipathic alpha helices separated by a large intervening span region. This helix-span-helix (HSH) domain was unable to bind DNA when separated from the basic region, but was still capable of dimerization. The ability of the HSH domain to function as a module that promotes DNA binding through dimerization was further demonstrated by attaching it to the heterologous basic region of the c-Jun proto-oncogene product. The resulting chimeric protein specifically recognized an AP-1 DNA-binding site in the absence of an intact c-Jun leucine repeat and in a manner that was dependent on the presence of a functional AP-2 dimerization domain.