Biomedical subjects

L You

Publications and source records attributed to L You.

At least 55 records · Page 3Linked to original sources

PubMed2000

Neurotrophic factors in the human cornea.

PURPOSE: To investigate neurotrophic growth factors and corresponding receptors in human and rabbit corneal epithelium and stroma. METHODS: Transcription of nerve growth factor (NGF), neurotrophin 3 (NT-3), NT-4, brain-derived neurotrophic factor (BDNF), glial cell line- derived neurotrophic factor (GDNF), and receptors Trk A-E, was investigated by reverse transcription-polymerase chain reaction. DNA dot blot analysis allowed to estimate transcription levels. Single cell proliferation assays were performed using recombinant NGF, BDNF, and GDNF. Mitogen-activated protein kinase signal transduction was investigated with Western blot analysis using antibodies against activated and total extracellular signal-regulated kinase (ERK) 1/2 and the jun N-terminal protein kinase (JNK) 1/2. RESULTS: Transcription of NGF, NT-3, BDNF, and Trk A, Trk B, Trk C, and Trk E receptors was detected in both ex vivo and cultured epithelium and stroma. Transcription of NT-4 was only detected in epithelium and transcription of GDNF only in stroma. Levels of transcription were higher for NT-3, NT-4, and the Trk receptors and lower for NGF, BDNF, and GDNF. NGF and GDNF stimulated both epithelial colony formation and proliferation, whereas BDNF only enhanced colony formation. Stromal proliferation was enhanced in serum-free medium. In epithelium, predominantly ERK 1 was activated by NGF, GDNF, and BDNF. In stromal cells NGF and GDNF stimulated phosphorylation of ERK 1 and JNK 1. CONCLUSIONS: Neurotrophic factors and tyrosine kinase receptors are transcribed in the human cornea. GDNF and NGF stimulate corneal epithelial proliferation, and the effect of the latter might be mediated by activation of ERK 1. Neurotrophic factors have very specific effects on phosphorylation of ERK and JNK in epithelial and stromal cells. The differential expression of NT-4 and GDNF suggests a regulatory function within the cytokine network of the cornea.

Animals↗

PubMed2000

[Matrix metalloproteinase-1 and coronary atheroslerotic plaque rupture].

OBJECTIVE: To investigate the relationship between matrix metalloproteinase-1 (MMP-1) and coronary atherosclerotic plaque rupture, and the cellular source of MMP-1 within the plaques. METHODS: 42 cases, among which 20 died of acute myocardial infarction, 10 with unstable angina history and 12 with stable angina history but died of other diseases, were selected. All the branch of coronary arteries were examined, parts of the segments were selected for immunohistochemical staining, 5 markers against alpha-smooth muscle actin, CD20, CD45RO, CD68 and MMP-1 were performed. RESULTS: Plaque rupture and thrombosis were found in almost all the cases of acute myocardial infarction and unstable angina. But in the cases of stable angina, the majority of the plaques were stable ones. The expression of MMP-1 in the ruptured plaques were stronger than the unruptured ones (t = -8.07, P < 0.05); Positive relationship was also noted between the expression of CD68 and MMP-1 (r = 0.75, P < 0.05). CONCLUSION: Macrophages are capable of degrading extracellular matrix by secreting MMP-1; Enhanced secretion of MMP-1 within the coronary atherosclerotic plaques has significant relationship with plaque rupture.

Angina, Unstable↗

PubMed1999

In utero exposure to antiandrogens alters the responsiveness of the prostate to p,p'-DDE in adult rats and may induce prostatic inflammation.

DDE is an environmental pollutant with antiandrogenic properties. Following administration to pregnant rats, DDE was shown to cause feminization in the male offspring at the neonatal stages but did not affect the pubertal growth of accessory sex organs. In this study, we examined the potential of in utero exposure to antiandrogens to alter the responsiveness of the male rats to subsequent DDE challenge. Pregnant Long-Evans rats were dosed by gavage from Gestation Day 14 to 18 at 0, 10 (low dose), or 100 (high dose) mg DDE, or 40 mg flutamide/kg body wt (bw)/day (in utero treatment). At approximately 80 days of age, the male offspring from each of the four in utero treatment groups were divided into two groups. One group received the adult treatment of four daily gavage administrations of DDE at 70 mg/kg bw (adult treatment), while the second group served as the adult treatment control (adult control). The in utero treatment resulted in 18, 31, and 53% reductions of ventral prostate weights at approximately 85 days of age compared to the control for the low- and high-dose DDE and flutamide groups, respectively. These results suggest that the in utero antiandrogen treatments produced a latent effect on prostate growth that became pronounced only in the postpubertal stage. The in utero treatment also altered the responsiveness of the prostate to the adult treatment, indicated by a significant reduction in ventral prostate weight that was seen only in the control group of the in utero treatment but not in the other groups. The in utero treatment was also associated with expression of testosterone-repressed prostatic message-2 in the adult ventral prostate. In addition, a few prostates in the high-dose DDE- and flutamide-treated groups of the in utero treatment were found to have chronic suppurative prostatitis. While other types of hormonal manipulations have been shown to incite similar responses in rat prostate, the possible linkage between in utero antiandrogen treatment and prostatic inflammation needs to be further evaluated.

Adipose Tissue↗

PubMed1999

Amplification and spread of viruses in a growing plaque.

The two-dimensional propagation of viruses through a "lawn" of receptive hosts, commonly called plaque growth, reflects the dynamics of interactions between viruses and host cells. Here we treat the amplification of viruses during plaque growth as a reaction-diffusion system, where interactions among the virus, uninfected host cells, and virus-producing host-virus complexes are accounted for using rates of viral adsorption to and desorption from the host-cell surface, rates of reproduction and release of progeny viruses by lysis of the host, and by the coupling of these reactions with diffusion of free virus within the agar support. Numerical solution of the system shows the development of a traveling wave of reproducing viruses, where the velocity of the wave is governed by the kinetic and diffusion parameters. The model has been applied to predict the propagation velocity of a bacteriophage plaque. Different mechanisms may account for the dependence of this velocity on the host density during early stages of a growing plaque. The model provides a means to explore how changes in the virus-host interactions may be manifest in a growing plaque.

Escherichia coli↗

PubMed1999

Modulation of testosterone-metabolizing hepatic cytochrome P-450 enzymes in developing Sprague-Dawley rats following in utero exposure to p,p'-DDE.

1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) causes sexual developmental aberrations in male rats through a likely mechanism of androgen receptor antagonism. DDE is also known to induce liver cytochrome P-450 (CYP). The expression of CYP enzymes is regulated by steroid hormones, which, in turn, are inactivated in the liver by CYP-catalyzed hydroxylations and subsequent conjugations. This study was undertaken to examine the potential of in utero DDE exposure to affect the developmental expression of the hepatic CYP enzymes that are responsible for testosterone hydroxylations. Pregnant Sprague-Dawley rats were dosed daily by gavage with DDE at 0, 10, or 100 mg/kg body weight or with flutamide at 40 mg/kg body weight from gestation day 14 to 18. Additional adult male rats were given seven daily doses of DDE at 100 mg/kg. Liver samples were collected from the offspring of the dosed dams on postnatal days (PND) 10 and 21 and from the adult rats a day after the last dosing. Assays for regioselective and sterospecific testosterone hydroxylase activities were performed using hepatic microsomal preparations. Specific liver CYP proteins were detected by immunoblotting. While the CYP2B1 and 3A1 and their hydroxylated testosterone products were highly elevated by the DDE treatments in both adult and developing rats, the responses of 2C11 and 2A1 were development-dependent. The flutamide treatment had little effect on CYP enzyme expression. This study demonstrated that developing offspring rats are susceptible to the hepatic CYP enzyme-modulating action of DDE following its administration to the pregnant dams.

Age Factors↗

PubMed1999

Transplacental and lactational transfer of p,p'-DDE in Sprague-Dawley rats.

p,p'-DDE (hereafter DDE), a persistent metabolite of p,p'-DDT, is a widespread environmental contaminant that can induce antiandrogenic developmental effects in rats. Quantitative measurements of the transfer of DDE from pregnant or lactating dams to the fetus or suckling neonate were performed, and physiologically based pharmacokinetic (PBPK) models for the transplacental and lactational transfer of DDE were developed. Pregnant Sprague-Dawley rats were dosed by gavage in corn oil with either 10 or 100 mg DDE per kg body wt per day from Gestation Day (gd) 14 to 18. DDE was analyzed in several maternal tissues as well as in fetal and neonatal tissues from gd 15 to Postnatal Day (pnd) 21. Fetal DDE concentrations were about threefold lower than corresponding placental concentrations. By adopting a cross-fostering design, the contributions of transplacental and lactational transfer were compared. In the pup liver, where DDE was detectable in the 100 mg/kg groups on pnd 10, the lactationally exposed group had DDE concentrations about 50 times higher than those of the in utero only exposure group; the lactation only exposure groups had DDE tissue dose profiles very similar to those of the in utero plus lactation exposure groups, indicating that the lactational route is far more important than the in utero route quantitatively. The PBPK models postulated initial absorption of DDE into both the blood circulation and lymphatic system with the primary storage sites being maternal and neonatal adipose tissues. Mobilization of DDE from its storage sites is postulated to occur via its association with mobilized fatty acids and lipoproteins. The results provide an overall framework for evaluating the tissue dosimetry of DDE and for understanding how maternal exposure to DDE could affect perinatal sexual development in utero or in the early postnatal period.

Adipose Tissue↗

PubMed1999

Developmental effects of dietary phytoestrogens in Sprague-Dawley rats and interactions of genistein and daidzein with rat estrogen receptors alpha and beta in vitro.

Estrogenic isoflavones, such as genistein and daidzein, are present in virtually all natural-ingredient rodent diets that use soy as a source of protein. Since these compounds are endocrine-active, it is important to determine whether the amounts present in rodent diets are sufficient to affect sexual development. The present study consisted of in vitro and in vivo parts. In the in vitro portion, human hepatoma cells were transfected with either rat estrogen receptor (ER) alpha or beta plus an estrogen-responsive luciferase reporter gene. Genistein and daidzein were complete agonists at both ERs, genistein being more potent than daidzein, and both compounds were more potent at ER beta than ER alpha. In combined studies with estradiol, genistein exerted additive effects with estradiol in vitro. In the in vivo portion of the study, groups of six pregnant Sprague-Dawley females were fed one of the following four diets, and the pups were maintained on the same diets until puberty: (1) a natural-ingredient, open-formula rodent diet (NIH-07) containing 16 mg genistein and 14 mg daidzein per 100 g of feed; (2) a soy- and alfalfa-free diet (SAFD) in which casein and corn oil were substituted for soy and alfalfa meal and soy oil, respectively, that contained no detectable isoflavones; (3) SAFD containing 0.02% genistein (GE.02); or (4) SAFD containing 0.1% genistein (GE.1). In the GE.1 group, effects of dietary genistein included a decreased rate of body-weight gain, a markedly increased (2.3-fold) uterine/body weight (U/BW) ratio on postnatal day (pnd) 21, a significant acceleration of puberty among females, and a marginal decrease in the ventral prostate weight on postnatal day (pnd) 56. However, developmental differences among the groups fed SAFD, GE.02, or NIH-07 were small and suggested minimal effects of phytoestrogens at normal dietary levels. In particular, on pnd 21, the U/BW ratio of the GE.02 and NIH-07 groups did not differ significantly from that of the SAFD group. Only one statistically significant difference was detected between groups fed SAFD and NIH-07: the anogenital distance (AGD) of female neonates on pnd 1 whose dams were fed NIH-07 was 12% larger than that of neonates whose dams were fed SAFD. The results suggest that normal amounts of phytoestrogens in natural-ingredient rodent diets may affect one developmental parameter, the female AGD, and that higher doses can affect several other parameters in both males and females. Based on these findings, we do not suggest replacing soy- and alfalfa-based rodent diets with phytoestrogen-free diets in most developmental toxicology studies. However, phytoestrogen-free diets are recommended for endocrine toxicology studies at low doses, to determine whether interactive effects may occur between dietary phytoestrogens and man-made chemicals.

Animals↗

PubMed1999

Morphometric and histological study of coronary plaques in stable angina and acute myocardial infarctions.

OBJECTIVE: To compare the morphological difference of coronary plaques in acute myocardial infarction and stable angina to clarify the occurrence basis of these two different myocardial events. METHODS: Sixty-eight acute myocardial infarction cases and 34 stable angina postmortem cases were studied. The coronary arteries were dissected en block, fixed, decalcified, sectioned at a 3 mm interval and processed routinely for histologic examination. A computor-aided planimeter was used to measure plaque and lipid core area. RESULTS: Among the total 4089 coronary blocks in acute myocardial infarction, 2087 (51.0%) had a lipid core over 40% of the plaque area; while among the total 2030 blocks in stable angina, only 209 (10.3%) had a lipid core over 40% of the plaque area (P < 0.05). Sixty-one of the 68 (89.7%) acute myocardial infarction cases had thrombi among which 56 occurred on ruptured plaques; while no thrombus was found in stable angina. In addition, atheroemboli were found in most of the thrombus-negative acute myocardial infarction cases (6/7) but none in SA cases. CONCLUSIONS: Acute myocardial infarction and stable angina had different morphologic basis of the coronary plaques. The former had more plaques with a large lipid core than the latter. Acute myocardial infarction was caused mainly by plaque rupture and associated thrombus. But atheroembolus could be another very important cause of acute myocardial infarction.

Aged↗

PubMed1999

[Morphometric study of inflammatory cells and smooth muscle cells in coronary plaques and their relation with plaque stability].

OBJECTIVE: To compare the content of inflammatory cells and smooth muscle cells in stable and unstable coronary plaques in order to clarify the role of these cells in the vulnerability of plaques. METHODS: Hearts from 12 postmortem acute myocardial infarction cases were studied. The epicardial coronary arteries were dissected en bloc, fixed, decalcified, cut at 4 mm intervals and routinely processed for HE sections. 163 stable plaques (with no or only little lipid core) and 163 unstable plaques (with lipid core size > 40% of plaque area) were studied immunohistochemically using monoclonal antibodies specific for macrophages (CD68), T lymphocytes (UCHL-1) and smooth muscle cells (actin). Computor aided planimetry was used to measure the positive area of different cells. RESULTS: The content of macrophage and T lymphocytes in unstable plaques were significantly higher than that in stable plaques (P < 0.05). CONCLUSIONS: Stable plaques and unstable plaques not only had different lipid core size but also had different inflammatory cell and smooth muscle cell content. The larger the lipid core and the more macrophages and T lymphocytes in the fibrous cap, the more unstable the plaque. The lipid core and inflammatory cells (including macrophages and T lymphocytes) are the two major determinants of the vulnerability of coronary plaques.

Actins↗

PubMed1999

Bone morphogenetic proteins and growth and differentiation factors in the human cornea.

PURPOSE: To investigate transcription of members of the transforming growth factor (TGF)-beta superfamily and corresponding receptors in human corneal epithelium and stroma. METHODS: Transcription of bone morphogenetic proteins (BMP)-2, BMP-3, BMP-4, BMP-5, and BMP-7; growth- differentiation factor (GDF)-5), and BMP receptors (BMPR) types I (BMPR-IA, BMPR-IB) and II (BMPR-II) was investigated by reverse transcription-polymerase chain reaction (RT-PCR) in ex vivo and cultured cells. For verification, PCR fragments were cloned and sequenced. DNA dot blot analysis was performed to estimate the level of transcription. RNA dot blots were performed to determine expression of GDF-5. Expression of BMP receptor proteins was investigated by immunohistochemistry. Single-cell clonal growth proliferation assays were performed using recombinant human GDF-5 and TGF-beta1. RESULTS: Transcription of BMP-2, BMP-3, BMP-4, BMP-5, and BMP-7 and receptors of BMPR-IA, BMPR-IB and BMPR-II was detected in ex vivo and cultured epithelium and stroma. The level of transcription was higher in cultured stroma for all factors, but the level for the receptors was higher in cultured epithelium. In contrast GDF-5 was transcribed only in stromal cells, suggesting that this cytokine may be an important mediator between keratocytes and epithelial cells. Furthermore, GDF-5 inhibited proliferation of corneal epithelial and stromal cells. CONCLUSIONS: Given the importance of the TGF-beta family during embryonic development, the results suggest that its members may be components of the corneal cytokine network and may participate in the regulation of cellular proliferation and differentiation.

Animals↗

PubMed1998

Regional brain dosimetry of trichloroethane in mice and rats following inhalation exposures.

While certain neuroactive volatile organic compounds (VOCs) have been reported to have an uneven distribution in various anatomically distinctive brain regions, this has not yet been reported for the short-chain aliphatic halogenated hydrocarbons. Therefore, the uptake and regional brain distribution of 1, 1, 1-trichloroethane (TRI) in mice and rats following inhalation exposure were examined. Male Sprague-Dawley rats and CD-1 mice were exposed to TRI at either 3500 or 5000 ppm for 10, 30, 60, or 120 min. Seven brain regions from rats and three from mice were sampled, and TRI concentrations in the blood and brain tissues were determined by headspace gas chromatography. In both species, the medulla oblongata was found to have the highest TRI concentrations, while cortex (in both species) and hippocampus (only sampled in rats) contained the lowest TRI concentrations. Substantial differences were also observed between the two species, as the mice exhibited higher capacity to accumulate TRI in the blood as well as in the brain regions. It appears that lipid content is a main factor influencing the differential disposition of TRI among the brains regions. Physiological differences in the respiratory systems of the two species and the physiochemical properties of the chemical favoring diffusion toward lipid-rich compartments could also have been expected to account for the patterns of regional distribution and species differences.

Administration, Inhalation↗

PubMed1998

Reduction in transforming growth factor-beta type II receptor in mouse lung carcinogenesis.

Transforming growth factor-beta (TGF-beta) is a growth modulator that inhibits the proliferation of many epithelial cells through interaction with its receptors, the type I and type II receptors (TGF-beta RI and RII) by activating their serine/threonine kinase activities. Loss of growth inhibition by TGF-beta is thought to contribute to the development of many types of tumors. To examine the roles of TGF-beta1, -beta2, and -beta3 and TGF-beta RI and RII in chemically induced mouse lung tumorigenesis, we used immunohistochemical and in situ hybridization analyses to measure the expression of their proteins and mRNAs in A/J mice treated with the carcinogen urethane to induce lung adenomas. Immunostaining for the TGF-beta ligands and receptors was detected in the epithelia of the bronchioles of untreated and treated A/J mice at similar levels. Immunostaining for the TGF-beta ligands and receptors was also detected in adenomas by 2 mo. While immunostaining for TGF-beta1, -beta2, and -beta3 and TGF-beta RI in adenomas was detected at levels comparable to those in bronchioles, immunostaining for TGF-beta RII was less intense in adenomas than in bronchioles. Decreased immunostaining for TGF-beta RII in adenomas persisted for at least 8 mo after exposure to urethane, whereas immunostaining for TGF-beta1, -beta2, and -beta3 and TGF-beta RI persisted at levels comparable to those in normal bronchioles. In situ hybridization studies conducted with TGF-beta receptor riboprobes showed a corresponding reduction in expression of TGF-beta RII mRNA but not of TGF-beta RI mRNA in adenomas compared with expression in bronchioles. Expression of TGF-beta RII mRNA was also examined in non-tumorigenic and tumorigenic mouse lung cells; expression of TGF-beta RII mRNA was lower in the tumorigenic cells derived from urethane-induced lung tumors. These data suggest that a decrease in expression of TGF-beta RII may contribute to autonomous cell growth and may play an important role in mouse lung carcinogenesis induced by urethane.

Activin Receptors, Type I↗

PubMed1998

Impaired male sexual development in perinatal Sprague-Dawley and Long-Evans hooded rats exposed in utero and lactationally to p,p'-DDE.

Although the pesticide DDT has been banned in the United States for decades, it remains at low levels in the environment. p,p'-DDE, a metabolite of DDT, was recently shown to inhibit the binding of androgens to the androgen receptor and to exert antiandrogenic effects in perinatal Long-Evans (LE) rats at a dose of 100 mg/kg/day administered to pregnant dams. In this study, we compared the effects of p,p'-DDE on male sexual development in offspring of Sprague-Dawley (SD) and LE rats. The chemical was dosed by gavage to pregnant dams at 10 or 100 mg/kg body wt from gestation day 14 to 18. The developing male rats were examined for sexual developmental landmarks, while the effects of p,p'-DDE on androgen receptor expression were evaluated in the testis and other reproductive organs. The tissue dosimetry of p,p'-DDE was also determined at different stages of development following in utero and lactational exposures. The higher p,p'-DDE dose induced a reduction in the male anogenital distance, an increase in retention of male thoracic nipples and alterations in expression of the androgen receptor in either one or both strains. A much weaker response was seen in the lower dose groups. Tissue and body fluid concentrations of p,p'-DDE were similar in the two strains in some tissues but dissimilar in others, particularly in the serum levels. Higher serum p,p'-DDE levels in the LE strain during pregnancy corresponded with an overall greater sensitivity of the LE strain to the antiandrogenic effects of p,p'-DDE. These results support the previous findings of p,p'-DDE antiandrogenicity in LE rats, extend the findings to SD rats, and suggest that the developmental effects of p,p'-DDE on male rat sexual differentiation are minimal at maternal doses below 10 mg/kg/day.

Animals↗

PubMed1998

Association of petrochemical exposure with spontaneous abortion.

OBJECTIVES: To assess the association between petrochemical exposure and spontaneous abortion, a retrospective epidemiological study in a large petrochemical complex in Beijing, China was conducted. METHODS: Plant employment records identified 3105 women who were married, were 20-44 years of age, and had never smoked. Of those, 3070 women (98.8%) reported at least one pregnancy. From this group, 2853 (93%) of the women participated in the study. According to their plant employment record, about 57% of these women workers reported occupational exposure to petrochemicals during the first trimester of their pregnancy. Trained interviewers administered a standardised questionnaire to this group of women and their husbands, collecting information on reproductive history, pregnancy outcomes, employment history, occupational exposure, smoking habits, alcohol consumption, indoor air pollution, and demographic variables. The results from the womens' first pregnancies were analysed. RESULTS: There was a significantly increased risk of spontaneous abortion for women working in all of the production plants with frequent exposure to petrochemicals (8.8%; range of 5.8%-9.8%) compared with those working in nonchemical plants (2.2%; range of 0.0%-7.1%). Also, when a comparison was made between exposed and non-exposed groups within each plant, exposure to petrochemicals was consistently associated with an increased risk of spontaneous abortion. The overall odds ratio (OR) was 2.7 (95% confidence interval (95% CI) 1.8 to 3.9) after adjusting for potential confounders. When the analysis was performed with the exposure information obtained from the women' interview responses for (self reported) exposures, the estimated OR for spontaneous abortions was 2.9 (95% CI 2.0 to 4.0). The analysis was repeated by excluding those 452 women who provided inconsistent reports between recalled exposure and work history, and a comparable risk of spontaneous abortion (OR 2.9; 95% CI 2.0 to 4.4) was found. In analyses for exposure to specific chemicals, an increased risk of spontaneous abortion was found with exposure to most chemicals, and the results for benzene (OR 2.5; 95% CI 1.7 to 3.7), gasoline (OR 1.8; 95% CI 1.1 to 2.9), and hydrogen sulphide (OR 2.3; 95% CI 1.2 to 4.4) were significant. CONCLUSION: An increased risk of spontaneous abortion was found associated with the exposure to petrochemicals, including benzene, gasoline, and hydrogen sulphide.

Abortion, Spontaneous↗

PubMed1998

Androgen receptor expression in the testes and epididymides of prenatal and postnatal Sprague-Dawley rats.

The androgen receptor (AR) plays a critical role in sexual differentiation and in the virilization of the male reproductive system. A clear understanding of AR expression at the early stages of sexual development will help elucidate the sensitivity of perinatal animals to endocrine modulation by external agents, such as some environmental chemicals. Immunohistochemistry was used in this study to localize the AR in the differentiating testis and epididymis of Sprague-Dawley rats starting from gestation day 15 until postnatal day 21. Positive AR staining was found on gestation day 15 in the mesenchymal as well as in the epithelial cells in the mesonephros. Weak staining was also observed in a small number of interstitial cells in the primordial testis at this age. The fetal interstitial and peritubular myoid cells showed positive AR immunoreactivity early in development, but the Sertoli cells did not overtly express the receptors until postnatal day 5. The intensity of staining and number of AR-positive cells in the testis and epididymis increased over time. The epithelium in the mesonephros-derived tissues, including rete testis and epididymis, appeared to exhibit a higher capacity to express AR than the rest of the testicular tissue. The results demonstrate that AR expression in the primordial male reproductive system is highly specific to time and cell type and modify previous understanding on the timing of AR expression in the testicular tissue. Since AR-positive cells at various developmental stages may be potential sites of interaction with chemicals that adversely affect sexual differentiation, improved understanding of AR ontogeny will help in investigating the effects of AR-reactive agents, such as environmental antiandrogens, with respect to specific windows of sensitivity.

Animals↗

PubMed1997

Differential regulation of protease and extracellular matrix protein expression by transforming growth factor-beta 1 in non-small cell lung cancer cells and normal human bronchial epithelial cells.

In addition to autoregulating its own expression, transforming growth factor-beta 1 (TGF-beta1) also regulates the production of proteases, protease inhibitors and extracellular matrix proteins. To investigate the relationship between plasminogen activator (PA), plasminogen activator inhibitor-1 (PAI-1) and the extracellular matrix in malignant and normal lung epithelial cells and to determine whether malignant lung epithelial cells may be more invasive than normal lung epithelial cells because of differences in expression of these proteins in response to TGF-beta, the regulation of PA, PAI-1, fibronectin, laminin and thrombospondin by TGF-beta1 in human non-small cell lung cancer (NSCLC) cells was examined and compared with normal human bronchial epithelial (NHBE) cells. TGF-beta1 caused a persistent increase in expression of the mRNAs for both PA and PAI-1 in NSCLC cells, with the increase in PAI-1 mRNA beginning several hours before that of PA mRNA. By immunoprecipitation analysis, it was shown that TGF-beta1 also induced a corresponding increase in the amount of PAI-1 protein in these NSCLC cells as well. In contrast, while TGF-beta1 also increased expression of PAI-1 mRNA in NHBE cells, expression of PA mRNA decreased simultaneously. Treatment of NSCLC cells with TGF-beta1 resulted in a persistent increase in expression of the mRNAs for fibronectin, laminin and thrombospondin; expression of fibronectin protein also increased after treatment with TGF-beta1 in these cells. When NHBE cells were similarly cultured in the presence of TGF-beta1, expression of fibronectin mRNA also increased in a persistent manner; however, only an early transient increase in the level of the mRNAs for laminin and thrombospondin was detected in these cells. These data show that there is differential regulation of the genes for PA and PAI-1 and the extracellular matrix protein fibronectin in response to TGF-beta1 not only when NSCLC and NHBE cells are compared, but also when different NSCLC cells are compared with each other.

Bronchi↗

PubMed1997

Identification of early growth response gene-1 (Egr-1) as a phorbol myristate acetate-induced gene in lung cancer cells by differential mRNA display.

Cellular regulatory genes including transcription factors may play an important role in the induction, maintenance, and progression of lung cancer. These regulatory genes are inducible by various mitogenic stimuli including phorbol myristate acetate (PMA). The differential mRNA display method was used to identify potential early response genes regulated by PMA in non-small cell lung cancer (NSCLC) cell lines. Using this technique, several cDNA fragments were found to be potentially differentially regulated by PMA in the squamous NSCLC cell line NCI-H157. One of these cDNA fragments of approximately 100 bp was determined to be differentially induced by at least 30-fold by PMA by northern blot analysis and to hybridize to a single 3.4 kb mRNA species. This cDNA fragment was cloned, sequenced, and identified to be identical to a portion of the 3'-untranslated region of the human early growth response gene-1 (Egr-1). Using Egr-1 cDNA as a probe, it was demonstrated that PMA induces Egr-1 mRNA expression in at least three other NSCLC cells as well. In addition, PMA caused a transient increase in expression of the Egr-1 transcript reaching a maximum level by 1 h before decreasing in NCI-H157 and three other types of NSCLC cells. Treatment of these NSCLC cells with TGF-beta1 showed a transient increase in Egr-1 mRNA similar to PMA which also reached a maximum level after 1 h. Normal human bronchial epithelial (NHBE) cells also showed a rapid, transient increase in expression of Egr-1 mRNA after treatment with PMA. In contrast, treatment of NHBE cells with TGF-beta1 showed that expression of Egr-1 mRNA increased by 1 h but reached a maximum level only after 6 h. These results indicate that both PMA and TGF-beta1 can induce Egr- mRNA expression in NSCLC cells and NHBE cells; however, while PMA induces Egr-1 mRNA similarly in both cell types, TGF-beta1 induces Egr-1 mRNA expression more rapidly and more transiently in NSCLC cells than in NHBE cells. Our results suggest that Egr-1 may play different roles in response to mitogens in normal and malignant lung cells.

Base Sequence↗

PubMed1997

Effects of transforming growth factor-beta 1 and phorbol ester on PAI-1 and PA genes in human lung cells.

Transforming growth factor-beta (TGF-beta) mediates the production of extracellular matrix proteins, proteases and protease inhibitors in epithelial cells. Both TGF-beta and phorbol-12-myristate-13-acetate (PMA) exert both positive and negative effects on mitogenesis in these as well as other cell types. Phorbol esters act through stimulation of protein kinase C (PKC) and are among the most potent tumor promoters known. The present study was conducted to determine whether the effect of TGF-beta in human non-small cell lung cancer (NSCLC) and normal human bronchial epithelial (NHBE) cells parallels that of the phorbol esters and whether this effect of TGF-beta involves PKC. TGF-beta 1 and PMA increased expression of TGF-beta 1 mRNA 24 hr after their addition to both NSCLC and NHBE cells. The effects of these agents on expression of the mRNAs for TGF-beta 2 and TGF-beta 3 were more complex; while TGF-beta 2 and TGF-beta 3 mRNAs increased transiently in response to TGF-beta 1 in NHBE cells and TGF-beta 3 mRNA increased transiently in some NSCLC cells, expression of these mRNAs decreased in most of these cells in response to PMA with the exception of the carcinoid NCI-H727 where TGF-beta 2 mRNA increased dramatically, TGF-beta 1 and PMA both caused a persistent increase in expression of the mRNAs for both plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator (PA) up to 24 hr in most NSCLC cells, with the increase in PAI-1 mRNA beginning several hours before that of PA mRNA. In contrast, while TGF-beta 1 also increased expression of PAI-1 mRNA in NHBE cells, the expression of PA mRNA decreased simultaneously. The effect of PMA on PAI-1 and PA mRNAs was opposite of TGF-beta 1 in these cells, with expression of PAI-1 mRNA decreasing and PA mRNA increasing after addition of PMA. These data show that there is parallel regulation of the genes for TGF-beta 1, PAI-1 and PA by TGF-beta 1 and PMA in NSCLC, but differential regulation of the genes for PAI-1 and PA by these agents in NHBE cells. The responses of the mRNAs and proteins of TGF-beta 1, PAI-1 and PA to TGF-beta 1 and PMA were inhibited by the serine/ threonine kinase inhibitor H7 in NSCLC cells. Treatment of NSCLC cells with TGF-beta 1 and PMA resulted in a persistent increase in the expression of fibronectin mRNA and protein. This response was blocked by the addition of H7. Inhibition of these effects by H7 in NSCLC cells suggests that H7 blocks TGF-beta responses by inhibiting a protein serine/threonine kinase(s). Because the effects of TGF-beta and PMA on the different TGF-beta isoforms, PA, PAI and fibronectin in NHBE and NSCLC cells are complex, our data suggest that there are distinct mechanisms for controlling the different TGF-beta isoforms, PA, PAI and extracellular matrix proteins in normal lung and lung cancer cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗