Biomedical subjects
Publications and source records attributed to Q Meng.
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Germ-line mutations of the breast cancer susceptibility gene 1 (BRCA1) confer a high risk for breast and ovarian cancer in women and prostate cancer in men. The BRCA1 protein contributes to cell proliferation, cell cycle regulation, DNA repair and apoptosis; however, the mechanisms underlying these functions of BRCA1 remain largely unknown. Here, we showed that, in Du-145 human prostate cancer cells, enhanced expression of BRCA1 resulted in constitutive activation of signal transducer and activator transcription factor 3 (STAT3) tyrosine and serine phosphorylation. Moreover, Janus kinase 1 (JAK1) and JAK2, the upstream activators of STAT3, were also activated by BRCA1. Immunoprecipitation assay showed that BRCA1 interacted with JAK1 and JAK2. Blocking STAT3 activation using antisense oligonucleotides significantly inhibited cell proliferation and triggered apoptosis in Du-145 cells with enhanced expression of BRCA1. These findings indicate that BRCA1 interacts with the components of the JAK-STAT signaling cascade and modulates its activation, which may provide a new critical survival signal for the growth of breast, ovarian and prostate cancers in the presence of normal BRCA1.
The BRCA1 gene was previously found to inhibit the transcriptional activity of the estrogen receptor [ER-alpha] in human breast and prostate cancer cell lines. In this study, we found that breast cancer-associated mutations of BRCA1 abolish or reduce its ability to inhibit ER-alpha activity and that domains within the amino- and carboxyl-termini of the BRCA1 protein are required for the inhibition. BRCA1 inhibition of ER-alpha activity was demonstrated under conditions in which a BRCA1 transgene was transiently or stably over-expressed in cell lines with endogenous wild-type BRCA1 and in a breast cancer cell line that lacks endogenous functional BRCA1 (HCC1937). In addition, BRCA1 blocked the expression of two endogenous estrogen-regulated gene products in human breast cancer cells: pS2 and cathepsin D. The BRCA1 protein was found to associate with ER-alpha in vivo and to bind to ER-alpha in vitro, by an estrogen-independent interaction that mapped to the amino-terminal region of BRCA1 (ca. amino acid 1-300) and the conserved carboxyl-terminal activation function [AF-2] domain of ER-alpha. Furthermore, several truncated BRCA1 proteins containing the amino-terminal ER-alpha binding region blocked the ability of the full-length BRCA1 protein to inhibit ER-alpha activity. Our findings suggest that the amino-terminus of BRCA1 interacts with ER-alpha, while the carboxyl-terminus of BRCA1 may function as a transcriptional repression domain. Oncogene (2001) 20, 77 - 87.
We have studied the influence of wasp venom immunotherapy (VIT) on cellular recruitment and cytokine mRNA expression during allergen-induced cutaneous late-phase responses (LPR). Nine subjects with a history of wasp sting anaphylaxis, and specific IgE in their sera underwent wasp VIT. Skin biopsies were taken 24 h after intradermal diluent and allergen before and after 3 months VIT. Pre-immunotherapy, there were significant allergen-induced increases in EG2(+) eosinophils, elastase(+) neutrophils, CD68(+) macrophages and IL-10 protein(+) cells, and increased expression of mRNA for IL-4, IL-13, IFN-gamma, IL-12, IL-10, TGF-beta, RANTES and eotaxin. When these allergen-induced changes in cytokine mRNA and cellular profiles were compared with those obtained after 3 months VIT there was a significant reduction in IL-4 mRNA (p=0.012) and increase in IL-10 protein(+) cells (p=0.004) with a trend to an increase in IL-10 mRNA (p=0.054). There were also significant reductions in eosinophils (p<0.004) and the size of the cutaneous LPR (p<0.01) but no change in mRNA to IFN-gamma, IL-13 or IL-12. Therefore, VIT is associated with a significant increase in cells positive for IL-10 protein but not IL-12 or IFN-gamma. These results suggest that induction of IL-10 may be important in VIT and occur independently of the switch to a Th1 phenotype. IL-10 generation may down-regulate IL-4 expression and eosinophil recruitment.
UNLABELLED: P73, a new p53 homologue, has been recently identified as a candidate tumor suppressor gene. PURPOSE: We studied the alterations in p73 in a panel of human cancer cell lines treated with the chemotherapeutic agent, Adriamycin (ADR), in comparison with the changes in p53. METHODS: P73 and p53 mRNA and protein were determined using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. ADR cytotoxicity was examined by a trypan blue dye exclusion assay. RESULTS: The cell lines bearing wild-type p53 were more susceptible to ADR than the cell lines bearing mutant p53. ADR treatment resulted in a significant accumulation of p53 protein and mRNA expression in the wild-type p53 cell lines and caused little (slight increase) or no influence on p53 expression in the cell lines with p53 mutation and deletion. However, in striking contrast to the alterations in p53, a decline in p73 at both the protein and mRNA levels was observed in all the cell lines examined following ADR treatment. Further studies indicated that this p53-independent downregulation of p73 was induced by ADR in a dose- and time-dependent manner. Moreover, the p73 protein decline was abrogated by the presence of proteasome inhibitors. CONCLUSIONS: Our findings revealed that although p73 shares a similar structural and functional composition with p53, there is a significant difference in the mechanisms that govern the responses of p53 and p73 to ADR-induced DNA damage.
BACKGROUND: Macrophage inflammatory protein (MIP)-1alpha binds to C-C chemokine receptor (CCR)-1 with high affinity. CCR-1 is expressed on neutrophils, eosinophils, monocytes, T lymphocytes and basophils; cells characteristic of atopic allergic inflammation. In vitro, MIP-1alpha is chemotactic for monocytes, T cells and basophils and is also a potent histamine-releasing factor for basophils and mast cells. Although increased levels of MIP-1alpha were shown in atopic allergic disorders, the kinetics of expression of these CC chemokines in vivo is largely unknown. OBJECTIVE: To investigate the kinetics of expression of MIP-1alpha and receptor CCR-1 and the relationships between the expression and infiltration of inflammatory cells in allergen-induced cutaneous late-phase reactions in atopic subjects. METHODS: Cryostat sections, obtained from skin biopsies from 10 human atopic subjects at 6, 24, 48, 72 h and 7 days after allergen challenge, were processed for immunohistochemistry and in situ hybridization using 35S-labelled riboprobes. RESULTS: The peak expression of allergen-induced mRNA for MIP-1alpha and CCR-1 was 6 h. This was maintained at 24 h, and gradually returned to base line at 7 days. At 6 h, the number of cells expressing MIP-1alpha mRNA significantly correlated with elastase+ neutrophils and BB-1+ basophils. At 24 h, the MIP-1alpha mRNA+ cells significantly correlated with CD68+ macrophages. There were significant inverse correlations between the numbers of MIP-1alpha mRNA cells and the numbers of Tryptase+ mast cells at 6 and 24 h after allergen challenge. CONCLUSION: Allergen-induced cutaneous late-phase reactions in humans were associated with increased expression of MIP-1alpha and CCR-1. This may be relevant to the infiltration of neutrophils, eosinophils, basophils and macrophages.
BACKGROUND: The demonstration of epsilon germline gene (Cepsilon) transcripts and mature mRNA for the epsilon heavy chain gene (Iepsilon) in the nasal mucosa suggested that IgE synthesis may occur in allergic rhinitis. OBJECTIVE: In view of our previous demonstration of increases in IL-4 mRNA(+) cells in asthmatic subjects, we assessed whether local IgE synthesis may also be a feature of bronchial asthma. METHODS: Fiberoptic bronchoscopic mucosa biopsy specimens were obtained from 9 atopic asthmatic subjects and 10 nonatopic normal (intrinsic) control subjects. To control for atopy, we also studied 9 nonatopic asthmatic subjects and 10 atopic nonasthmatic control subjects. Tissue was processed for immunohistochemistry for B cells (CD20) and in situ hybridization for Iepsilon and Cepsilon RNA(+) cells and IL-4 mRNA(+) cells. RESULTS: B-cell numbers in the bronchial mucosa were similar for asthmatic subjects compared with control subjects, whereas significantly higher numbers of Iepsilon RNA(+) (P =.02 and P =.04, respectively), Cepsilon RNA(+) (P =.01 and P =.03, respectively), and IL-4 mRNA(+) (P =.001 and P =.001, respectively) cells were observed in atopic asthmatic subjects and nonatopic asthmatic subjects, respectively, but not in atopic control subjects compared with nonatopic control subjects. In asthmatic subjects there were significant correlations between Iepsilon RNA(+) cells (r = 0.54, P =.02) and Cepsilon RNA(+) cells (r = 0.48, P =.05) when compared with the number of IL-4 mRNA(+) cells. CONCLUSION: Increases in Iepsilon and Cepsilon RNA(+) cells, but not B-cell numbers, in the bronchial mucosa provide evidence for local IgE synthesis in both atopic and nonatopic asthma. These changes appear to relate to asthma rather than atopy per se and, at least in part, may be under the regulation of IL-4.
BACKGROUND: Isolated late asthmatic reactions can be provoked by intradermal challenge of allergen-derived T-cell peptide epitopes. OBJECTIVE: The purpose of this study was to determine whether the isolated LAR is associated with the local accumulation of inflammatory cells, the expression of T(H)2 cytokines, and the production of pharmacologic mediators. METHODS: A randomized, placebo-controlled, crossover study design was used. The investigation involved bronchial and skin biopsies and bronchoalveolar lavage (BAL) fluids from 8 cat-allergic subjects who developed significant late asthmatic reactions 6 hours after intradermal injection of Fel d 1 chain 1-derived peptides (FC1Ps). RESULTS: Immunostaining of bronchial biopsy specimens showed no changes in the numbers of eosinophils, neutrophils, basophils, mast cells, CD3(+), CD4(+) or CD8(+) T cells, CD25(+) cells or macrophages, or cells mRNA(+) for IL-4, IL-5, or IL-13 when the FC1P day was compared with the diluent control day. There were also no significant differences in eosinophil numbers, either in BAL fluids or in peripheral blood after FC1P challenge. Furthermore, there were no significant alterations in the concentrations of histamine, histamine-releasing factors, or eicosanoids (LTC(4)/D(4)/E(4), PGD(2), PGE(2), TXB(2), PGF(2alpha)) in BAL fluids. FC1Ps induced a significant (P <.05) elevation in CD8(+) cells in the skin and an unexpected decrease in IL-5 in BAL fluids (P =.043). CONCLUSION: Part of the asthma process might involve T cell-dependent airway narrowing with no requirement for IgE, mast cells, or infiltrating inflammatory cells.
The B. subtilis pyrG gene, which encodes CTP synthetase, is located far from the pyrimidine biosynthetic operon on the chromosome and is independently regulated. The pyrG promoter and 5' leader were fused to lacZ and integrated into the chromosomes of several B. subtilis strains having mutations in genes of pyrimidine biosynthesis and salvage. These mutations allowed the intracellular pools of cytidine and uridine nucleotides to be manipulated by the composition of the growth medium. These experiments indicated that pyrG expression is repressed by cytidine nucleotides but is largely independent of uridine nucleotides. The start of pyrG transcription was mapped by primer extension to a position 178 nucleotides upstream of the translation initiation codon. A factor-independent termination hairpin lying between the pyrG promoter and its coding region is essential for regulation of pyrG expression. Primer-extended transcripts were equally abundant in repressed and derepressed cells when the primer bound upstream of the terminator, but they were much less abundant in repressed cells when the primer bound downstream of the terminator. Furthermore, deletion of the terminator from pyrG-lacZ fusions integrated into the chromosome yielded elevated levels of expression that was not repressible by cytidine. We suggest that cytidine repression of pyrG expression is mediated by an antitermination mechanism in which antitermination by a putative trans-acting protein is reduced by elevated levels of cytidine nucleotides. Conservation of sequences and secondary structural elements in the pyrG 5' leaders of several other gram-positive bacteria indicates that their pyrG genes are regulated by a similar mechanism.
We have developed an automated multiplex system for simultaneously screening hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) in blood donations. The assay, designated AMPLINAT MPX HBV/HCV/HIV-1 Test (AMPLINAT MPX), consists of virus extraction and target sequence-specific probe capture on specimen preparation workstation GT-X (Roche Diagnostics K.K., Tokyo, Japan) and amplification and detection by TaqMan PCR on the ABI PRISM 7700 Analyzer (Perkin-Elmer Applied Biosystems, Foster City, Calif.). An internal control (IC) is incorporated in the assay to monitor the extraction, target amplification, and detection processes. The assay yields qualitative results without discrimination of the three targets. Detection limits (95% confidence interval) are 22 to 60 copies/ml for HBV, 61 to 112 IU/ml for HCV, and 33 to 66 copies/ml for HIV-1, using a specimen input volume of 0.2 ml. The AMPLINAT MPX assay detects a broad range of genotypes or subtypes for all three viruses and has a specificity of 99.6% for all three viruses with seronegative specimens. In an evaluation of seroconversion panels, the AMPLINAT MPX assay detects HBV infection an average of 24 days before the detection of HBsAg by enzyme immunoassay. HCV RNA was detected an average of 31 days before HCV antibody. HIV-1 RNA was detected an average of 14 days before HIV-1 antibody and an average of 9 days before p24 antigen. The Japanese Red Cross has been evaluating the AMPLINAT MPX system since October 1999. The clinical performance indicates that the AMPLINAT MPX system is robust, sensitive, and reproducible, with a high percentage of valid assay runs (96.8%), a low false-positive rate (0.34%), and a low IC failure rate (0.24%).
Hepatocyte growth factor (scatter factor) (HGF/SF) is a pleiotrophic mediator of epithelial cell motility, morphogenesis, angiogenesis, and tumorigenesis. HGF/SF protects cells against DNA damage by a pathway from its receptor c-Met to phosphatidylinositol 3-kinase (PI3K) to c-Akt, resulting in enhanced DNA repair and decreased apoptosis. We now show that protection against the DNA-damaging agent adriamycin (ADR; topoisomerase IIalpha inhibitor) requires the Grb2-binding site of c-Met, and overexpression of the Grb2-associated binder Gab1 (a multisubstrate adapter required for epithelial morphogenesis) inhibits the ability of HGF/SF to protect MDCK epithelial cells against ADR. In contrast to Gab1 and its homolog Gab2, overexpression of c-Cb1, another multisubstrate adapter that associates with c-Met, did not affect protection. Gab1 blocked the ability of HGF/SF to cause the sustained activation of c-Akt and c-Akt signaling (FKHR phosphorylation). The Gab1 inhibition of sustained c-Akt activation and of cell protection did not require the Gab1 pleckstrin homology or SHP2 phosphatase-binding domain but did require the PI3K-binding domain. HGF/SF protection of parental MDCK cells was blocked by wortmannin, expression of PTEN, and dominant negative mutants of p85 (regulatory subunit of PI3K), Akt, and Pak1; the protection of cells overexpressing Gab1 was restored by wild-type or activated mutants of p85, Akt, and Pak1. These findings suggest that the adapter Gab1 may redirect c-Met signaling through PI3K away from a c-Akt/Pak1 cell survival pathway.
OBJECTIVE: This study was to analyze the relationship among pathology, clinic and laboratory indexes in 62 cases of the acute severe hepatitis (ASH) and 72 cases of the subacute severe hepatitis(SSH) to offer a correct diagnosis and recognition of the disease. METHODS: A total of 134 severe hepatitis cases with confirmed pathology treated in a course of 24 years were analyzed by programs of EXCEL 2000. RESULTS: When compared ASH with SSH, the onset of the age were 40 +/- 13 years old and 44 +/- 15 years old, P < 0.05, the rates of hepatitis coma were 100% and 66.7% respectively. The liver weight of all the cases decreased. The tests of TBiL, PTA, Cho, NH3 and WBC between ASH and SSH had significant differences. CONCLUSION: Hepatic encephalopathy is a necessary criterion for ASH. The TBiL, PTA and Cho changes are closely related with severe viral hepatitis, they not only are the essential laboratory indexes but also the indispensable factors for disease development and prognosis of severe viral hepatitis.
OBJECTIVE: Cerebral infarction, a common acute cereovascular disease, is one of the main complications of type 2 diabetes mellitus (DM). This paper is to explore the risk factors of cerebral infarction among type 2 DM patients. METHODS: A pair-matched case-control study was carried out. Data was analyzed with conditional logistic regression. RESULTS: One hundred and ten type 2 DM patients with cerebral infarction and controls were selected respectively. Results showed that higher educational level and physical exercises lowered the risk of cerebral infarction among type 2 DM patients. Higher HDL-C and blood sugar under control could also lower the risk of developing cerebral infarction among type 2 DM patients. The above factors seemed to have protective functions. Excessive salt intake and snoring increased the risks of cerebral infarction development among type 2 DM patients. Hypertension served as an independent risk factor while atrial fibrillation and hyperinsulinemia were important risk factors. High LDL-C, Apo-A, Lp(a), Fg increased the risk of cerebral infarction among type 2 DM patients. The study did not discover the relationship of smoking, drinking, oral contraception, menstrual and obstetrical history, TC, TG, Apo-A and cerebral infarction among type 2 DM patients. CONCLUSION: To prevent cerebral infarction among type 2 DM, measures need to be taken as control of salt intake; eating more vegetables; regular physical exercises; control of blood sugar, blood pressure and Hyperinsulinemia.
OBJECTIVE: To investigate the diagnostic features of CT and MRI in chordoma of the skull base (CSB) and to estimate their value of clinical application. METHODS: Sixteen patients with CSB were performed CT and MRI examinations of the head, and 13 patients with nasopharyngeal carcinoma (NPC) and 11 patients with pituitary adenoma (PA) which invaded the skull base were selected as control. In addition, 7 cases of chordoma were performed multiple planar reconstruction (MPR) of MRI. RESULTS: MRI was superior to CT in depicting the location and the extent of CSB. The bone destruction at mid-line skull base was demonstrated equally well on both CT and MRI. Based on the location of the tumor displayed on MRI, the CSB could be classified into selloclival, nasopharyngeal, and occipito-temperal types. The T2 weight imaging(T2WI) signal intensity of chordoma was significantly higher than those of NPC and PA (P < 0.01). On MPR images of MRI, oppressed and displaced optic nerves caused by chordoma were noted in 3 cases and encased optic nerves in 4 cases, encased abducent nerves in 7 cases with abducent paralysis and mildly oppressed oculomotor nerves in 3 cases. CONCLUSION: The extremely high T2WI signal intensity is the characteristic of MRI finding in CSB and has great differential value for the tumors of the skull base. The MPR of MRI plays an important role in the surgical treatment for these tumors.
OBJECTIVE: To investigate the operative modes for adrenal medullary hyperplasia. METHODS: 8 cases of adrenal medullary hyperplasia were treated with transposition of pedicled adrenal gland. The inferior and the medial blood vessel of adrenal gland were ligated. The superior blood vessel of adrenal gland was formed a 5.0- 6.0 cm pedicle and dragged to the subcutaneous of dorsum. RESULT: After follow-up for an average of 2 years, only 1 of the 8 patients did not recover as a result of psychosis and others had no symptoms but normal endocrine results. CONCLUSION: Transposition of the pedicled adrenal gland is a simple and satisfied way to treat patients with adrenal medullary hyperplasia.
Drug combinations that include nucleoside reverse transcriptase inhibitors (NRTIs) are remarkably effective in preventing maternal-viral transmission of HIV during pregnancy. However, there may be potential long-term risks for children exposed in utero. Examination of the genotoxic and mutagenic effects of two NRTIs, zidovudine [AZT (3'-azido-3'-deoxythymidine)] and didanosine [ddI (2',3'-dideoxyinosine)], in cultured human lymphoblastoid cells revealed multiplicative synergistic enhancement of AZT-DNA incorporation and mutant frequency induction in response to the combined drug exposure, as compared with single-drug exposures. Dose-related increases in DNA incorporation of AZT (as measured by a competitive RIA) and mutagenicity at the HPRT and TK loci (as assessed by cell-cloning assays) were observed in cells exposed in culture to AZT, or equimolar combinations of AZT + ddI, at exposure concentrations ranging from 3 to 30 times the maximum plasma levels found in humans. Because mutagenesis is strongly associated with tumor induction in experimental models, children exposed transplacentally to combinations of NRTIs may be at risk for cancer development later in life.
Epidemiological studies suggest that moderate alcohol consumption increases the risk of breast cancer, and that alcohol combined with estrogen replacement therapy may synergistically enhance the risk. However, the mechanism(s) of alcohol-induced mammary cancer is unknown. In human breast cancer cell lines, we found that ethanol (EtOH) caused a dose-dependent increase of up to 10- to 15-fold in the transcriptional activity of the liganded estrogen receptor (ER-alpha), but did not activate the nonliganded receptor. Significant stimulation of ER-alpha activity was observed at EtOH concentrations comparable with or less than blood alcohol levels associated with intoxication and at doses below the threshold for in vitro cytotoxicity. These findings may be explained, in part, by an EtOH-induced down-regulation of the expression of BRCA1, a potent inhibitor of ER-alpha activity, and, in part, by a modest increase in the ER-alpha levels. Our findings suggest that inactivation of BRCA1 and increased estrogen-responsiveness might contribute to alcohol-induced breast cancer.
Of the four known tissue inhibitors of metalloproteinases (TIMPs), TIMP-3 is distinguished by its tighter binding to the extracellular matrix. The present results show that glycosaminoglycans such as heparin, heparan sulfate, chondroitin sulfates A, B, and C, and sulfated compounds such as suramin and pentosan efficiently extract TIMP-3 from the postpartum rat uterus. Enzymatic treatment by heparinase III or chondroitinase ABC also releases TIMP-3, but neither one alone gives complete release. Confocal microscopy shows colocalization of heparan sulfate and TIMP-3 in the endometrium subjacent to the lumen of the uterus. Immunostaining of TIMP-3 is lost upon digestion of tissue sections with heparinase III and chondroitinase ABC. The N-terminal domain of human TIMP-3 was expressed and found to bind to heparin with affinity similar to that of full-length mouse TIMP-3. The A and B beta-strands of the N-terminal domain of TIMP-3 contain two potential heparin-binding sequences rich in lysine and arginine; these strands should form a double track on the outer surface of TIMP-3. Synthetic peptides corresponding to segments of these two strands compete for heparin in the DNase II binding assay. TIMP-3 binding may be important for the cellular regulation of activity of the matrix metalloproteinases.