Triiodothyronine (T3) upregulates the expression of proto-oncogene TGFA independent of MAPK/ERK pathway activation in the human breast adenocarcinoma cell line, MCF7

ABSTRACT Objective: To verify the physiological action of triiodothyronine T3 on the expression of transforming growth factor α (TGFA) mRNA in MCF7 cells by inhibition of RNA Polymerase II and the MAPK/ERK pathway Materials and methods: The cell line was treated with T3 at a physiological dose (10−9M) for 10 minutes, 1 and 4 hour (h) in the presence or absence of the inhibitors, α-amanitin (RNA polymerase II inhibitor) and PD98059 (MAPK/ERK pathway inhibitor). TGFA mRNA expression was analyzed by RT-PCR. For data analysis, we used ANOVA, complemented with the Tukey test and Student t-test, with a minimum significance of 5%. Results: T3 increases the expression of TGFA mRNA in MCF7 cells in 4 h of treatment. Inhibition of RNA polymerase II modulates the effect of T3 treatment on the expression of TGFA in MCF7 cells. Activation of the MAPK/ERK pathway is not required for T3 to affect the expression of TGFA mRNA. Conclusion: Treatment with a physiological concentration of T3 after RNA polymerase II inhibition altered the expression of TGFA. Inhibition of the MAPK/ERK pathway after T3 treatment does not interfere with the TGFA gene expression in a breast adenocarcinoma cell line.

Salivary transforming growth factor alpha in patients with Sjögren's syndrome and reflux laryngitis / Estudo da concentração salivar do fator transformador de crescimento alfa em indivíduos com Sindrome de Sjögren e refluxo laringofaríngeo

Introduction: Saliva plays a key role in the homeostasis of the digestive tract, through its inorganic components and its protein growth factors. Sjögren's syndrome patients have a higher prevalence of gastroesophageal reflux disease and laryngopharyngeal reflux. Decreased salivary transforming growth factor alpha levels were observed in dyspeptic patients, but there have been no studies in patients with Sjögren's syndrome and laryngopharyngeal reflux. Objective: To compare the salivary transforming growth factor alpha levels of patients with Sjögren's syndrome and laryngopharyngeal reflux to those of healthy controls. Methods: This is a prospective controlled study. Twelve patients with Sjögren's syndrome and laryngopharyngeal reflux and 11 controls were prospectively evaluated. Spontaneous and stimulated saliva samples were obtained to establish salivary transforming growth factor alpha concentrations. Results: The salivary transforming growth factor alpha levels of patients were significantly higher than those of healthy controls. Five patients with laryngopharyngeal reflux also had erosive esophagitis; their salivary transforming growth factor alpha levels were comparable to controls. Conclusion: Salivary transforming growth factor alpha level was significantly higher in patients with Sjögren's syndrome and laryngopharyngeal reflux when compared to the control group. .

Introdução: A saliva exerce influência primordial na homeostase do sistema digestório, pelos seus componentes inorgânicos e pelos fatores de crescimento. Indivíduos com sindrome de Sjögren (SS) apresentam maior incidência da doença do refluxo gastroesofágico (DRGE) e do refluxo laringofaríngeo (RLF). Concentrações salivares diminuídas do fator transformador de crescimento alfa (TGF-α) foram observadas em doentes dispépticos, porém não há estudos em populações com SS e RLF. Objetivo: Comparar concentrações salivares do TGF-α; de indivíduos com SS e RLF a de controles saudáveis. Método: Trata-se de um estudo prospectivo controlado. Doze pacientes com SS e RLF e 11 indivíduos controles saudáveis tiveram amostras salivares espontâneas e estimuladas coletadas para estabelecer concentração de TGF-α. Resultados: A concentração salivar de TGF-α; foi estatisticamente maior no grupo estudo para ambas amostras. Este aumento foi confirmado nos sete indivíduos do grupo estudo que não apresentavam esofagite erosiva quando comparados ao grupo controle, porém não houve diferença estatística da concentração de TGF-α; entre pacientes do grupo estudo que apresentava mesofagite erosiva em comparação ao grupo controle. Conclusão: A concentração salivar de TGF-α; foi estatisticamente maior no grupo de indivíduos com SS e RLF, sem esofagite erosiva. .

Expression of ErbB Receptor Proteins and TGF-alpha during Diethylnitrosamine-induced Hepatocarcinogenesis in the Rat Liver / 대한간학회지

BACKGROUND/AIMS: ErbB receptor proteins are transmembrane tyrosine kinase receptors; when they are activated by interaction with ligands, they generate diverse cellular responses, especially during lesion development and progression to cancer. In this study the expression of ErbB receptors and TGF-alpha were investigated using an experimental cirrhosis rat model giving rise to hepatocellular neoplasms, similar to human liver diseases. METHODS: Fifty three male rats received intraperitoneal injection of diethylnitrosamine (DEN, 50 mg/kg), weekly for 18 weeks. Until the eighth week, two rats were sacrificed every two weeks and from the tenth to the eighteenth week, five rats were sacrificed weekly. Grossly, dyschromatic and dysmorphic nodules were counted and categorized into three groups: N1/N2/N3: 3 mm or = 10 mm in diameter. All nodules were examined, histologically. Antibodies for GSTp, TGF-alpha, EGF-R, ErbB2, ErbB3 and ErbB4 were used for immunohistochemistry. RESULTS: The onset of cirrhoses was noted from the twelfth week. Preneoplastic foci, hepatocellular adenomas (HCA) and hepatocellular carcinomas (HCC) were noted from the second, eleventh and fifteenth week, respectively. The nodules (N1/N2/N3: 397/258/64) included regenerating nodule; RN (N1/N2/N3: 72.3%/15.9%/0%), HCA (N1/N2/N3: 27.2%/82.2%/7.6%) and HCC (N1/N2/N3: 0.5%/ 1.9%/92.4%). EGF-R was expressed in 12.5% of RN, 64.7% HCA and 75.2% HCC. TGF-alpha was expressed in 92.4% of RN, 91.3% HCA and 93.2% HCC. Sixty eight percent of TGF-alpha expressing nodules showed concurrent EGF-R expression. ErbB2 was expressed in 83.6% of RN, 72.9% HCA and 88.7% HCC. ErbB4 was expressed in 95.2% of RN, 86.3% HCA and 62.5% HCC. CONCLUSIONS: Increased expression of EGF-R and decreased expression of ErbB4, might be related with tumor progression during DEN-induced hepatocarcinogenesis.

Study of events leading cellular senescence to human mammary epithelial cancer cells in vitro.

Role of various growth regulatory factors in inducing senescence in cultured HMEC cells have been investigated in ten cases of breast cancer. The histological grade of tumour cells is found to play significant role in controlling the proliferation and phenotypic charateristics of cultured HMEC cells during primary culture and also number of subsequent passages resulting in complete cellular senescence in them. Effects of conditioned media (CM) collected from primary and senescent cultures of these HMEC cells had also been studied on proliferation of their own HMEC cells used as target cells, to evaluate the role of various autocrine growth factors produced by them. Significant increase in proliferation of target cells was noticed on their exposure to CM from senescent cultures, while cessation of their proliferation was found on their exposure to CM from senscent cultures, suggesting that HMEC cells produce growth promoting factors during primary culture and growth inhibitory factors on subsequent passages, responsible for inducing features of cellular senescence in them. The role of epidermal growth factors (EGF) and transforming growth factors (TGF) alpha and beta as autocrine factors in inducing senescence of cultured HMEC cells were also investigated. Deletion of EGF from growth media initially caused decreased proliferation to target HMEC cells, followed by improvement in their proliferation. Supplementation of growth media by TGF-alpha induced significant increase in proliferation of target cells. Addition of epidermal growth factors receptor (EGFR) antibody to cells exposed to media devoid of EGF and media supplemented with TGF-alpha showed marked suppression of proliferation of target cells. The morphologic and phenotypic characteristics of target HMEC cells exposed to TGF-alpha were also found similar to those HMEC cells grown during primary culture, suggesting autocrine production of EGF and TGF-alpha by cultured HMEC cells during primary culture. Supplementation of TGF-beta to growth media induced marked suppression of proliferation to target cells along with morphologic and phenotypic features of terminal differntiation or senescence. Exposure of senescent cells to media supplemented with EGF and TGF-alpha could not induce their proliferation. This suggest that HMEC cells on subsequent passages undergo some genetic and phenotypic alterations resulting in production of growth inhibitory factor like TGF-beta which induces cessation of their proliferation alone with features of senescence.

The effect of aflatoxin B1 on the expression of early response genes and transforming growth factor-alpha in CCl4 induced rat liver injury

Aflatoxin B1 (AFB1), a fungal toxin produced by Aspergillus flavus, is known to be a possible hepatocarcinogen. But the molecular biologic changes which may occur following exposure to AFB1 are not known and thus the carcinogenesis is not yet understood. This study was performed to examine the expressions of c-myc, c-fos and TGF-alpha genes and to investigate the possible role of those molecular biologic changes in hepatic regeneration and in the development of hepatocellular carcinoma (HCC). Sprague-Dawley rats were divided into 3 groups: Carbon tetrachloride (CCl4) only was administered to group I, AFB1 only was administered to group II and a combination of AFB1 and CCl4 was administered to group III. The animals were sacrificed at 0.5, 1, 2, 6, 12, 24, 48, and 72 hours after treatment. In addition to the examination of the hematoxylin-eosin stained sections, hepatic regeneration and apoptosis were analyzed quantitatively by bromodeoxyuridine (BrdU)-anti-BrdU immunohistochemistry and TUNEL assay utilizing apoptosis kit, respectively. The hepatic expressions of c-myc, c-fos and transforming growth factor-alpha (TGF-alpha) were examined by immunohistochemistry and studied by Western blot. The number of BrdU labelled cells and the degree of necrosis/apoptosis were comparable among the different groups. Livers of the group II rats showed nearly normal histology without regeneration and necrosis/apoptosis. In groups I and III, the number of BrdU- labelled cells showed an increase at 48 hours after treatment, and the increment was significantly higher in group I than in group III. Most BrdU-labelled cells were mature hepatocytes in group I, whereas in group III they appeared to be less mature. In group I, apoptosis showed an increase at around 24 hours, but appeared in group III as early as 12 hours after treatment and persisted through 48 hours. The expression of c-myc and c-fos were also different between the experimental groups. The expression intensity of c-myc in group I was highest at 1 hour and decreased thereafter. In groups II and III, the expressions were much more intense than in group I, except at 1 hour, and the increased intensity persisted throughout the experiment. Group II in particular showed a peak intensity at 30 minutes and at 6 hours after treatment. In group I, c-fos was strongly expressed only at 24 hours, but in group III, there was progressively increased expression with peak intensity at 24 hours. TGF-alpha was expressed in similar intensities in all groups throughout the experiment. These results suggest that AFB1 may evoke an intense and protracted expression of c-myc, provocating the CCl4-induced necrosis of hepatocytes, and a prolonged expression of c-fos, including persistent signals for regeneration which in turn may activate the replication of immature cells. These findings will aid further investigation of molecular biologic and histologic characteristics of the hepatotoxic and hepatocarcinogenic mechanism of AFB1 in rats. And these results in rats, together with clinico-epidemiologic and molecular biologic investigations in humans and other animals, suggest that AFB1 may supply hepatocarcinogenic background in early exposure time in AFB1-contaminated areas of China and Korea.