Relationship between tumor suppressor gene RUNX3 expression and cell proliferation and apoptosis in colonic cancer cell line Lovo

AIM: To investigate the expression and methylation status of tumor suppressor gene RUNX3 in human colon cancer cell line Lovo and explore the effects of 5-aza-2'-deoxycytidine (5-Aza-CdR) on the proliferation and apoptosis of Lovo cells and the expression of RUNX3 gene.

METHODS: Human colon cancer cell line Lovo was treated with 5-Aza-CdR, a specific methyltransferase inhibitor, at the concentrations of 0.4, 4 and 40 μmol/L for 3 d, and then cultured in RPMI 1640 medium for 5 d. The activation of Lovo cells was respectively observed by Tetrazolium salt colorimetric (MTT) assay before and after 5-Aza-CdR treatment. The change in expression of RUNX3 mRNA was observed by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The apoptosis was analyzed by flow cytometry. The methylation status of gene promoter was determined by methylation-specific PCR (MSP).

RESULTS: Lovo cells treated with 5-Aza-CdR (0.4, 4, 40 μmol/L) displayed a slowed growth rate in different degrees in contrast with those in the control group and their growth rates decreased accordingly with the increase of 5-Aza-CdR concentration. There were significant increases in RUNX3 mRNA expression (0.46 ± 0.06, 0.71 ± 0.06, 0.84 ± 0.07 vs 0, P < 0.01) and apoptotic rates of Lovo cells (10.95% ± 2.09%, 17.61% ± 1.51%, 26.60% ± 1.89% vs 2.92% ± 0.93%, P < 0.01) after 5-Aza-CdR treatment in comparison with those in the control group. The level of RUNX3 mRNA expression and the apoptotic rates of Lovo cells were increased in correlation with 5-Aza-CdR concentration (F = 168.4, F = 145.7, P < 0.01). Methylation of RUNX3 promoter region was confirmed in Lovo cells of control group and detected partly in 5-Aza-CdR-treated group.

CONCLUSION: 5-Aza-CdR is able to reverse the methylation status of RUNX3 promoter region. The re-expression of RUNX3 gene can inhibit Lovo cell growth and partly induce Lovo cell apoptosis.

A community-based epidemiological study of periodontal disease in Keelung, Taiwan: a model from Keelung community-based integrated screening programme (KCIS No. 18)

AIMS

To estimate the prevalence and severity of periodontal disease (PD) in the Taiwanese population aged 35-44 years and to investigate the association between demographic factors and PD.

MATERIALS AND METHODS

Between 2003 and 2005, residents of Keelung of the appropriate age were invited to screening. The community periodontal index (CPI) and loss of attachment (LA) index were used to measure the periodontal status at subject (prevalence) and sextant levels (severity). Basic demographic information was also collected by a questionnaire.

RESULTS

Of 8462 enrollees, 94.8% had some signs of PD, of whom 29.7% had periodontal pockets >3 mm and 35% LA >3 mm. Calculus was the most common problem in terms of both prevalence (49.6%) and severity (affecting an average of 3.0 sextants per person). Risk factors for poor periodontal status (as measured by CPI) were older age (odds ratio, OR: 1.44), male gender (OR: 2.70), low education level (OR: 1.40), and being a manual worker (OR: 1.51). Similar findings were observed for LA.

CONCLUSION

The prevalence of PD in 35-44-year-olds was found to be high in this large community-based study of screening for PD with CPI and LA. Poorer periodontal health was observed in males, the less educated, and manual workers.

Survivin: Potential role in diagnosis, prognosis and targeted therapy of gastric cancer

Survivin is a protein that is highly expressed in a vast number of malignancies, but is minimally expressed in normal tissues. It plays a role as an inhibitor of cell death in cancer cells, thus facilitating the growth of these cells. In the case of gastric cancer, survivin is over-expressed in tumor cells and plays a role in the carcinogenesis process. Several studies on gastric cancer have indicated that there is a relationship between survivin expression and the ultimate behavior of the carcinoma. Since the expression pattern of survivin is selective to cancer cells, it has been described as an “ideal target” for cancer therapy. Currently, several pre-clinical and clinical trials are on-going to investigate the effects of interfering with survivin function in cancer cells as a biologic therapy. Survivin is a potentially significant protein in the diagnosis, prognosis and treatment of gastric tumors.

Synthesis, crystal structure and biological activity of 2-[2-(quinolin-2-yl)vinyl]-8-hydroxyquinoline and 2-[2-(quinolin-4-yl)vinyl]-8-hydroxyquinoline

Two new isomeric 8-hydroxyquinoline derivatives with quinoline groups have been synthesized by Perkin condensation. Their structures were characterized by EI-MS,1H NMR spectroscopy, elemental analysis and FT–IR spectroscopy; crystal structures were determined by X-ray crystallography. 2-[2-(Quinolin-2-yl)vinyl]-8-hydroxyquinoline crystallizes in the tetragonal space groupI41/aand 2-[2-(quinolin-4-yl)vinyl]-8-hydroxyquinoline crystallizes in the monoclinic space groupP21/n. Hydrogen bonds and intermolecular interactions are observed in the compounds and stabilize their structures. The biological activities were investigated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and flow cytometry analysis, and the results revealed that the two compounds had effects on the proliferation of rat mesenchymal stem cells.

[In vitro cultivation of Echinococcus multilocularis metacestodes and observation of their growth]

OBJECTIVE

To observe the growth and development of Echinococcus multilocularis metacestodes under in vitro cultivation.

METHODS

Hepatoma cell line was used for the cultivation. The number and morphology of the cysts were observed under light microscope. The parasite tissue was fixed and observed under electron microscope.

RESULTS

During the first 21 days of cultivation, metacestodes in cyst-suspension derived cultures increased dramatically, and from the 22nd day on, the number of cysts remained as 6-7 times more than that of the 3rd-4th day of culture. Budding of new cysts was observed and the diameter of the cysts increased as time went on. On the 22nd day, larger cysts occupied 30%. Cysts were found with morphology between protoscolex and metacestode.

CONCLUSION

An in vitro cultivation for the cysts of E. multilocularis has been established and basic feature of growth and development of the larvae observed.

Neural differentiation of mesenchymal-like stem cells from cord blood is mediated by PKA

Mesenchymal stem cells (MSC) are multipotent and give rise to distinctly differentiated cells from all three germ layers. While umbilical cord blood derived mesenchymal-like cells were previously shown to be capable of differentiating into the neural lineage both in vitro and in vivo, the underlying molecular mechanisms and signal transduction pathways remain to be elucidated. In this study, we show that mesenchymal-like cells from umbilical cord blood are capable of neural differentiation and this capability is mediated by the Protein kinase A (PKA) signal transduction pathway. While activation of PKA via experimental cAMP upregulation leads to outgrowth of neurite-like structures as well as expression of neural marker genes, blocking PKA activity completely abolishes all these features. Thus, our results demonstrate that PKA function is sufficient and required for neurite-like outgrowth and regulation of neural specific gene expression in mesenchymal-like stem cells from cord blood.

Population-based family case-control proband study on familial aggregation of metabolic syndrome: finding from Taiwanese people involved in Keelung community-based integrated screening (KCIS no. 5)

A population-based case-control proband study was undertaken to elucidate familial aggregation, independent environmental factors, and the interaction between them. A total of 7308 metabolic syndrome (MET-S) cases were identified from the Keelung community-based integrated screening programme between 1999 and 2002. The study has a case-control/family sampling design. A total of 1417 case probands were randomly selected from 3225 metabolic syndrome cases and the corresponding 2458 controls selected from 16,519 subjects without metabolic syndrome by matching on sex, age (+/-3 years) and place of residence. The generalized estimation equation model was used to estimate odds ratios and corresponding 95% confidence intervals. The risk for having metabolic syndrome among family members for cases versus control probands was 1.56-fold (1.29-1.89) after controlling for significant environmental factors. Higher risk of metabolic syndrome was found in parents than spouse. Low education against high education had 2.06-fold (1.36-3.13) risk for metabolic syndrome. Betel quid chewing was positively associated with the risk of MET-S, with 1.99-fold (1.13-3.53) risk for 1-9 pieces and 1.76-fold (0.96-3.23) risk for >or=10 pieces compared with non-chewer. Moderate and high intensity of non-occupational exercise led to 21.0% (OR=0.79 (0.63-0.98)) and 26.0% (OR=0.74 (0.59-0.94)) reduction in the risk for metabolic syndrome, respectively. The frequent consumption of vegetable reduced 24.0% (OR=0.76 (0.62-0.92)) risk for MET-S. The frequent consumption of coffee was associated the increased risk for metabolic syndrome (OR=1.32 (1.07-1.64)). The present study confirmed the risk of metabolic syndrome not only has the tendency towards familial aggregation but is affected by independent effect of environmental or individual correlates.

8-Hydroxyquinoline derivatives induce the proliferation of rat mesenchymal stem cells (rMSCs)

A series of 8-hydroxyquinoline derivatives with different substituted groups at 2- or 5-position have been synthesized and characterized. Their effects on the proliferation of the rat marrow-derived mesenchymal stem cells (rMSCs) have been evaluated by MTT assay and flow cytometry. We also analyzed the ability of these compounds to regulate the proliferation of rMSCs and the relationship with the structures of 8-hydroxyquinoline. Compounds 8-11, in which, the vinyl-substituents are on the 2-position of 8-hydroxyquinoline, appear to be able to induce the proliferation of rMSCs. These results show that compounds 8-11 provide a kind of new substances for regulating the proliferation of rMSCs.

Evolution of multiple disease screening in Keelung: a model for community involvement in health interventions?

OBJECTIVE

Screening for cancer and other chronic conditions tends to be conducted in independent programmes; that is, screening for one disease at a time. The Keelung community-based multiple disease screening programme, developed in Keelung city, Taiwan, is a notable exception. Here, we report on the Keelung programme's ethos and development within the community, focusing on equity of delivery of the service, and community involvement. In addition, we present some preliminary cost-effectiveness analyses of multiple disease screening.

METHODS

The Keelung programme offers screening for breast, colorectal and liver cancers, cervical and oral neoplasia, all of which have an evidence base for their efficacy, and for diabetes, hypertension, osteoporosis and hyperlipidaemia, which are of unknown efficacy. We assessed variability of coverage rates of the Keelung Community-based Integrated Screening (KCIS) programme with age and socioeconomic status, availability of facilities for referral of positive screenees, and numbers of community social workers, general practitioners and local hospitals involved in the programme. We also assessed in qualitative terms how the programme interacts with non-health agencies. Finally, we simulated activities and costs for a variety of single- and multiple-disease screening situations.

RESULTS

Between 1999 and 2003, coverage increased overall from 14.7 to 34.4%, and increased most dramatically in people aged 60-79 years (from around 30 to 60%) and in those of lower educational status (from around 40 to 70%). There was a significant growth in the involvement of social workers and volunteers in the programme, and an increase in the availability of local diagnostic and care facilities for those screened positive. In addition, there was substantial involvement of non-health agencies in publicizing the programme. In the health economic simulations, compared with no screening, the extra costs to gain an additional life year were estimated as 667 US dollars, 608 US dollars, 4227 and 4789 US dollars for multiple screening with 100% attendance, multiple screening with 70% attendance, single disease screening with 100% attendance and single disease screening with 30% attendance at each programme (i.e. 74% attendance for at least one out of four programmes), respectively.

CONCLUSIONS

The innovative design and outreach procedures of the KCIS have led to a growth in delivery of screening services to groups sometimes overlooked (equity), community involvement in health care (participation) and the use of non-health organizations for publicity and health education (collaboration). Simulation studies indicate that multiple disease screening may be more cost-effective than single disease screening.

[Roles of vasodilator-stimulated phosphoprotein in the regulation of cytoskeleton]

Regulation of cytoskeletal dynamics is required to coordinate cell adhesion, morphology change and cell motility. Vasodilator-stimulated phosphoprotein (VASP) is an actin-binding protein which is composed of EVH1, EVH2 domains and PRR. It has been implicated in actin-based processes such as axon guidance, T cell polarization and fibroblast migrations. The regulation of VASP phosphorylation, which is controlled by PKG (cGMP-dependent protein kinase) and PKA (cAMP-dependent protein kinase), could correspond to the "switch" process in its communication with cytoskeleton during modification of focal adhesion.

Transformation systems of non-Saccharomyces yeasts

This review describes the transformation systems including vectors, replicons, genetic markers, transformation methods, vector stability, and copy numbers of 13 genera and 31 species of non-Saccharomyces yeasts. Schizosaccharomyces pombe was the first non-Saccharomyces yeast studied for transformation and genetics. The replicons of non-Saccharomyces yeast vectors are from native plasmids, chromosomal DNA, and mitochondrial DNA of Saccharomyces cerevisiae, non-Saccharomyces yeasts, protozoan, plant, and animal. Vectors such as YAC, YCp, YEp, YIp, and YRp were developed for non-Saccharomyces yeasts. Forty-two types of genes from bacteria, yeasts, fungi, and plant were used as genetic markers that could be classified into biosynthetic, dominant, and colored groups to construct non-Saccharomyces yeasts vectors. The LEU2 gene and G418 resistance gene are the two most popular markers used in the yeast transformation. All known transformation methods such as spheroplast-mediating method, alkaline ion treatment method, electroporation, trans-kingdom conjugation, and biolistics have been developed successfully for non-Saccharomyces yeasts, among which the first three are most widely used. The highest copy number detected from non-Saccharomyces yeasts is 60 copies in Kluyveromyces lactis. No general rule is known to illustrate the transformation efficiency, vector stability, and copy number, although factors such as vector composition, host strain, transformation method, and selective pressure might influence them.

Bcl-2 is not reduced in the death of MCF-7 cells at low genistein concentration

Soy consumption has been associated with a lower incidence of breast cancer in Southeast Asia. Among the phytochemicals in soy, genistein has been suggested to be chemopreventive. Because genistein is an estrogen-receptor (ER) agonist, the chemopreventive mechanism has been attributed to its ability to compete with estrogen for receptor binding. In this study, we used an ER-positive cell line to investigate the effects of different genistein concentrations on the apoptotic response. The threshold concentration at which a significant number of cells underwent apoptosis was titrated to be 25 micromol/L. At or above this concentration, c-jun N-terminus kinase was activated and Bax and Bcl-2 expression were both elevated. The elevated Bcl-2 protein might neutralize the proapoptotic effect of Bax. Therefore, the mechanism of genistein-induced apoptosis at this concentration might rely largely on the stress pathway rather than the pathway mediated by the Bcl-2 family of proteins.

Low-dose genistein induces cyclin-dependent kinase inhibitors and G(1) cell-cycle arrest in human prostate cancer cells

Genistein, a naturally occurring isoflavone found chiefly in soy products, reportedly has antiprostate cancer effects, but the mechanisms underlying these effects are unknown. We studied the antiproliferative and apoptosis-inducing effects of genistein in the androgen-sensitive human prostate cancer cell line LNCaP. Viable cell number was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay; cell-cycle progression and apoptosis were evaluated by flow cytometry; apoptosis was also assessed by a histone enzyme-linked immunosorbent assay; and the expression of several cell-cycle- and apoptosis-related genes and their gene products was determined by northern blot analysis, western blot analysis, and/or assays based on polymerase chain reaction. Physiologic concentrations of genistein (< or = 20 microM) decreased LNCaP viable cell number in a dose-dependent manner, induced a G(1) cell-cycle block, decreased prostate-specific antigen mRNA expression, and increased p27(KIP1) and p21(WAF1) (mRNA and protein) but had no effect on apoptosis or the mRNA expression of the apoptosis- and cell-cycle-related markers bcl-2, bax, Rb, and proliferating cell nuclear antigen. Higher concentrations of genistein (> 20 microM) did induce apoptosis. We conclude that genistein (at physiologic concentrations) exerts potent antiproliferative effects on LNCaP cells by inducing a G(1) cell-cycle block. The antiproliferative effects of genistein may be mediated by increased levels of p27(KIP1) and p21(WAF1), which are negative cell-cycle regulators that act as cyclin-dependent kinase inhibitors and that have been recently linked with prostate carcinogenesis. These findings may provide insights into the mechanisms underlying the apparent antiprostate cancer effects of soy consumption observed in epidemiologic studies.

Effects of calorie restriction on thymocyte growth, death and maturation

We previously reported that calorie restriction (CR) significantly delays the spontaneous development of thymic lymphomas and other neoplasms in p53-deficient mice and their wild-type littermates. The purpose of the present study was to further characterize the anti-lymphoma effects of CR by assessing thymocyte growth, death and maturation in response to acute (6 day) and chronic (28 day) CR regimens. Male C57BL/6J mice fed a CR diet (restricted to 60% of control ad libitum intake) for 6 days displayed a severe reduction in thymic size and cellularity, as well as a decrease in splenic size and cellularity; these declines were sustained through 28 days of CR. Mice maintained on a CR diet for 28 days also displayed a significant depletion in the cell numbers of all four major thymocyte subsets defined by CD4 and CD8 expression. Analysis within the immature CD4(-)8(-) thymocyte subset further revealed an alteration in normal CD44 and CD25 subset distribution. In particular, CR for 28 days resulted in a significant decrease in the percentage of the proliferative CD44(-)25(-) subset. In addition, a significant increase in the percentage of the early, pro-T cell CD44(+)25(-) population was detected, indicative of a CR-induced delay in thymocyte maturation. Taken together, these findings suggest that CR suppresses (through several putative mechanisms) lymphomagenesis by reducing the pool of immature thymocytes that constitute the lymphoma-susceptible subpopulation.

Low-dose genistein induces cyclin-dependent kinase inhibitors and G(1) cell-cycle arrest in human prostate cancer cells

Genistein, a naturally occurring isoflavone found chiefly in soy products, reportedly has antiprostate cancer effects, but the mechanisms underlying these effects are unknown. We studied the antiproliferative and apoptosis-inducing effects of genistein in the androgen-sensitive human prostate cancer cell line LNCaP. Viable cell number was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay; cell-cycle progression and apoptosis were evaluated by flow cytometry; apoptosis was also assessed by a histone enzyme-linked immunosorbent assay; and the expression of several cell-cycle- and apoptosis-related genes and their gene products was determined by northern blot analysis, western blot analysis, and/or assays based on polymerase chain reaction. Physiologic concentrations of genistein (< or = 20 microM) decreased LNCaP viable cell number in a dose-dependent manner, induced a G(1) cell-cycle block, decreased prostate-specific antigen mRNA expression, and increased p27(KIP1) and p21(WAF1) (mRNA and protein) but had no effect on apoptosis or the mRNA expression of the apoptosis- and cell-cycle-related markers bcl-2, bax, Rb, and proliferating cell nuclear antigen. Higher concentrations of genistein (> 20 microM) did induce apoptosis. We conclude that genistein (at physiologic concentrations) exerts potent antiproliferative effects on LNCaP cells by inducing a G(1) cell-cycle block. The antiproliferative effects of genistein may be mediated by increased levels of p27(KIP1) and p21(WAF1), which are negative cell-cycle regulators that act as cyclin-dependent kinase inhibitors and that have been recently linked with prostate carcinogenesis. These findings may provide insights into the mechanisms underlying the apparent antiprostate cancer effects of soy consumption observed in epidemiologic studies.

Catecholamines and angiotensinogen gene expression in kidney proximal tubular cells

To investigate the molecular mechanism(s) of action of catecholamines on the expression of the angiotensinogen (ANG) gene in kidney proximal tubular cells, we used opossum kidney (OK) cells with a fusion gene containing the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (rANG N-1498/+18), permanently integrated into their genomes. The level of expression of the ANG-GH fusion gene was quantified by the amount of immunoreactive-hGH (IR-hGH) secreted into the medium. The addition of norepinephrine (NE), isoproterenol (a beta1/beta2-adrenergic receptor (AR) agonist) and iodoclonidine (an alpha2-AR agonist) stimulated the expression of the ANG-GH fusion gene in a dose-dependent manner, whereas the addition of epinephrine and phenylephrine (alpha1-AR agonist) had no effect. The stimulatory effect of NE was blocked by the presence of propranolol (beta-AR blocker), atenolol (beta1-AR blocker), yohimbine (alpha2-AR blocker), Rp-cAMP (an inhibitor of cAMP-dependent protein kinase AI & AII) and staurosporine (an inhibitor of protein kinase C), but was not blocked by ICI 118, 551 (beta2-AR blocker) and prazosin (alpha1-AR blocker). The addition of a combination of isoproterenol and iodoclonidine or a combination of 8-Bromo-cAMP (8-Br-cAMP) and phorbol 12-myristate (PMA) synergistically stimulated the expression of the ANG-GH fusion gene as compared to the addition of isoproterenol, iodoclonidine, 8-Br-cAMP or PMA alone. Furthermore, the addition of NE, 8-Br-cAMP or PMA stimulated the expression of pOGH (rANG N-806/-779/-53/+18), a fusion gene containing the putative cAMP responsive element (CRE, ANG N-806/-779) upstream of the ANG promoter (ANG N-53/+18) in OK cells, but had no effect on the expression of fusion genes containing the mutant of the CRE. Gel mobility shift assays revealed that the ANG-CRE binds with the DNA-binding domain (bZIP254-327) of the cAMP-responsive binding protein (CREB). The binding of the labeled ANG-CRE to CREB (bZIP254-327) was displaced by unlabeled ANG-CRE and the CRE of the somatostatin gene but not by the mutants of the ANG-CRE. Finally, NE stimulated the phosphorylation of CREB in OK cells. These studies demonstrate that the molecular mechanism(s) of NE action on the expression of the ANG gene in OK cells may be mediated via both the PKA and PKC signalling pathways and via the phosphorylation of CREB. The phosphorylated CREB then interacts with the CRE in the 5'-flanking region of the ANG gene and subsequently stimulates the gene expression.

Inhibition of aromatase activity and expression in MCF-7 cells by the chemopreventive retinoid N-(4-hydroxy-phenyl)-retinamide

The effect of the chemopreventive synthetic retinoid N-(4-hydroxyphenyl)-retinamide (4-HPR) on aromatase activity and expression was examined. 4-HPR caused a dose-dependent inhibition of aromatase activity in microsomes isolated from JEG-3 human placental carcinoma cells. The kinetics of inhibition were analysed by double-reciprocal plot. The Km of the substrate increased and the Vmax of the reaction decreased in the presence of 4-HPR, indicating that enzyme inhibition involved both competition for the substrate-binding site and non-competitive mechanisms. To determine whether 4-HPR would also inhibit aromatase activity in intact cells, MCF-7 human breast cancer cells were incubated with or without cAMP in the presence of 4-HPR. 4-HPR inhibited both basal and cAMP-induced aromatase activity in intact MCF-7 cells. The induction of aromatase mRNA expression in MCF-7 cells by cAMP was inhibited in cells treated with 4-HPR. These results indicate that 4-HPR inhibits both the enzymatic activity and expression of aromatase. These activities may play an important role in the known chemopreventive effect of 4-HPR towards breast cancer.

Molecular mechanism(s) of insulin action on the expression of the angiotensinogen gene in kidney proximal tubular cells

To investigate the molecular mechanism(s) of insulin action on the expression of the angiotensinogen (ANG) gene in kidney proximal tubular cells, we constructed a fusion gene, pOGH (hANG N-1064/+27), containing the 5'-flanking regulatory sequence of the human ANG gene fused with the human growth hormone (hGH) gene as a reporter and stably integrated the fusion gene into the opossum kidney (OK) cell genomes. The level of expression of pOGH (hANG N-1064/+27) was quantified by the amount of immunoreactive hGH secreted into the medium. The addition of a high level of D(+)-glucose (25 mM) or phorbol 12-myristate 13-acetate (PMA, 10(-7) M) stimulated the expression of the fusion gene in OK cells. The stimulatory effect of glucose (25 mM) was blocked by insulin and tolrestat (an inhibitor of aldose reductase). Tolrestat also inhibited the increase of cellular DAG and PKC activity stimulated by 25 mM glucose. While insulin did not affect the cellular DAG and PKC activity, it did block the stimulatory effect of high glucose (25 mM) and PMA on the expression of the fusion gene. Finally, PD98059 (an inhibitor of mitogen-activated protein kinase kinase (MEK)) enhanced the stimulatory effect of high levels of glucose and blocked the inhibitory effect of insulin on the expression of the fusion gene as well as on the phosphorylation of MEK and mitogen-activated protein kinase (MAPK). In contrast, Wortmannin (an inhibitor of phosphatidylinositol-3-kinase) did not block the inhibitory effect of insulin on the ANG gene expression. These studies demonstrate that the action of insulin, blocking the stimulatory effect of a high level of D(+)-glucose (25 mM) on the ANG gene expression is mediated, at least in part, via the 5'-flanking region of the ANG gene and MAPK signal transduction pathway.

Coordinated regulation of two TRAIL-R2/KILLER/DR5 mRNA isoforms by DNA damaging agents, serum and 17beta-estradiol in human breast cancer cells

A search of the Genebank database revealed that there are two distinct gene sequences with the common name of TRAIL-R2/Killer/DR5. Using reverse transcription-polymerase chain reaction (RT-PCR), we confirmed the existence of two isoforms of TRAIL-R2/Killer/DR5 mRNA, which we have designated the long and short isoforms based on their electrophoretic mobility. We found that both the long and short mRNA isoforms are ubiquitously expressed in human tissues and cell lines. The long form generally predominates, but the proportion of the two isoforms varies depending on the tissue type. Treatment of MCF-7 human breast cancer cells with the DNA damaging drugs adriamycin, campthothecin, or etoposide causes a coordinated up-regulation of both isoforms. Treatment of the p53-mutant T-47D breast cancer cell line with adriamycin also results in up-regulation of both isoforms, suggesting that adriamycin up-regulates TRAIL-R2/Killer/DR5 expression independent of functional p53. The expression of both mRNA isoforms are increased in MCF-7 cells cultured in charcoal-stripped fetal bovine serum compared to normal serum, suggesting that sex steroid hormones may play a role in the negative regulation of their expression. This was confirmed in MCF-7 cells cultured in stripped serum supplemented with 17beta-estradiol, which also resulted in a decrease in the mRNA expression of both isoforms. These results demonstrate that the TRAIL-R2/Killer/DR5 gene gives rise to two distinct forms of mRNA, and that these two forms are coordinately regulated by DNA damage and 17beta-estradiol in human breast cancer cells. The functional significance of the two isoforms remains to be determined.

Paradoxical regulation of Bcl-2 family proteins by 17beta-oestradiol in human breast cancer cells MCF-7

Tumorigenesis is related to the dysregulation of cell growth or cell death pathways. Hence, elucidation of the mechanisms involved in the modulation of pro- or anti-apoptotic proteins is important in furthering understanding of breast cancer aetiology and may aid in designing prevention and treatment strategies. In the present study, we examined the role of 17beta-oestradiol on the regulation of apoptosis in the breast cancer cell line MCF-7. Using multi-probe RNAase protection assays, we found changes in the mRNA levels of several Bcl-2 family proteins upon treatment of MCF-7 cells with 17beta-oestradiol. Unexpectedly, we found a paradoxical effects of 17beta-oestradiol on two anti-apoptotic proteins Bcl-2 and Bcl-x. Treatment with 17beta-oestradiol resulted in up-regulation of Bcl-2 mRNA and protein, but down-regulated Bcl-x(L) mRNA and protein. The effect of 17beta-oestradiol on Bcl-x(L) occurred at concentration-dependent fashion. The effect was specific to 17beta-oestradiol since other steroid hormones exert no effect on Bcl-x(L). Tamoxifen, an anti-oestrogen, blocked the down-regulation of Bcl-x(L) by 17beta-oestradiol demonstrating this effect is oestrogen receptor-dependent. We speculate that different members of the Bcl-2 family proteins may be regulated through different pathway and these pathways may be modulated by 17beta-oestradiol.

The molecular biology of Schwanniomyces occidentalis klocker

This review describes the molecular studies of Schwanniomyces occidentalis (Debaryomyces occidentalis) concerning transformation, genome, gene cloning, gene structure, gene expression and its characteristics to application. Schw. occidentalis appears to have at least five or seven chromosomes and no native plasmid from the yeast has been reported. Four transformation systems based on complement of Schw. occidentalis auxotrophic mutants were established. Vectors with the replicon of 2-micron plasmid and autonomous replication sequences (ARS) of Saccharomyces cerevisiae and Schw. occidentalis ARS replicated extrachromosomally in Schw. occidentalis transformants, without modification of the transformed vector DNA. So far, at least 21 Schw. occidentalis genes encoding 14 different proteins have been cloned. Most of the Schw. occidentalis genes have shown homologies (45 to 91%) with the corresponding genes of other organisms, especially of S. cerevisiae. However, some Schw. occidentalis genes possess other unique structures for their operators, promoters, transcription initiation sites, and terminators. Some foreign genes were expressed in Schw. occidentalis, while Schw. occidentalis genes functioned in other yeasts and bacteria, Escherichia coli, and Streptomyces lividans. Due to a strong ability of secretion and low level of glycosylation, Schw. occidentalis might be a promising host to produce heterologous proteins.

Molecular mechanism(s) of action of isoproterenol on the expression of the angiotensinogen gene in opossum kidney proximal tubular cells

BACKGROUND

beta-adrenoceptors are present in the renal proximal tubules. We have previously reported that isoproterenol stimulates the accumulation of intracellular cAMP and the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells via the beta 1-adrenoceptor. We hypothesized that the molecular mechanism(s) of action of isoproterenol on the expression of the ANG gene is mediated via the interaction of the phosphorylated cAMP-responsive element binding protein (CREB) and the cAMP-responsive element (CRE; that is, ANG N-806/-779) in the 5'-flanking region of the rat ANG gene.

METHODS

The fusion genes containing the putative ANG-CRE of the rat ANG gene inserted upstream of the rat ANG basal promoter (ANG N-53/+18) fused to a human growth hormone (hGH) gene as reporter were stably cotransfected, with or without the plasmid containing the cDNA for 43 kDa CREB, into the OK cells. The effect of various agonists and antagonists of adrenoceptors on the expression of the fusion genes was evaluated by the amount of immunoreactive hGH secreted into the culture medium. The interactions of OK cellular nuclear protein(s) with the ANG N-806/779 were determined by gel mobility shift assays and by Southwestern and Western blot analysis.

RESULTS

The addition of isoproterenol, forskolin, or 8-Bromo-cAMP (8-Br-cAMP) stimulated the expression of pOGH (ANG N-806/-779/-53/+18) by 135, 150, and 160%, respectively, but not mutants of the ANG N-806/-779. The stimulatory effect of isoproterenol was blocked in the presence of propranolol, Rp-cAMP, and atenolol, but not by the presence of stauro-sporine, U73122, and ICI 118,551. Transient transfection of the plasmid containing the cDNA for the catalytic subunit of protein kinase A further enhanced the stimulatory effect of 43 kDa CREB on the expression of the fusion gene. The gel mobility shift assays revealed the the nuclear protein(s) of OK cells binds to the radioactive-labeled ANG N-806/-779. The binding of the labeled ANG N-806/-779 to the OK cell nuclear protein(s) was displaced by unlabeled ANG N-806/-779, but not by the CRE of the somatostatin gene, the CRE of the tyrosine amino-transferase gene, or the mutants of the ANG N-806/-779. Southwestern blot analysis revealed that the labeled ANG N-806/-779 binds to two nuclear species of 43 and 35 kDa proteins. Western blot analysis, however, revealed that rabbit polyclonal antibodies against the 43 kDa CREB interacted with only the 43 kDa molecular species but not with the 35 kDa species.

CONCLUSION

These studies demonstrate that the stimulatory effect of isoproterenol on the expression of the ANG gene may be mediated, at least in part, via the interaction of the phosphorylated CREB and the CRE in the 5'-flanking region of the rat ANG gene. The novel 35 kDa nuclear protein that is immunologically different from the 43 kDa CREB may also play a role in the expression of the ANG gene.

Differential effects of chemotherapeutic agents on the Bcl-2/Bax apoptosis pathway in human breast cancer cell line MCF-7

The present study explored the effects of three commonly used chemotherapeutic agents on the Bcl-2/Bax apoptosis pathway and the interaction of these chemotherapeutic drugs with the estradiol-mediated regulation of this pathway. Our results showed that: (1) Treatment of MCF-7 cells with Adriamycin resulted in time- and concentration-dependent decreases in Bcl-2 and increases in Bax mRNA and protein levels. (2) Camptothecin elicited similar trends on Bcl-2 and Bax as Adriamycin, while etoposide, at 50-100 fold (1-5 microM) the effective concentration of Adriamycin and camptothecin, only resulted in an increase in Bax mRNA levels. (3) Adriamycin and camptothecin, but not etoposide, were effective in suppressing estradiol-stimulated increases in Bcl-2 mRNA levels. Our study provides evidence that the Bcl-2/Bax apoptosis pathway may be differentially regulated by chemotherapeutic agents. In addition, interaction between these agents and estradiol on the Bcl-2/Bax apoptosis pathway may also exist.

Mechanistic studies of the effects of the retinoid N-(4-hydroxyphenyl)retinamide on prostate cancer cell growth and apoptosis

To explore the mechanisms underlying the chemopreventive effects of the synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) in prostate cancer, we evaluated the anti-proliferative and apoptosis-inducing effects of 4-HPR in the androgen-sensitive human prostate cancer cell line LNCaP. 4-HPR decreased the number of viable LNCaP cells (as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) in a dose-dependent manner. Although 4-HPR exerted a modest G1 cell-cycle block (as determined by flow cytometry), its effect on reduced cell number appeared to result primarily from induction of apoptosis (as measured by an enzyme-linked immunosorbent assay and flow-cytometric assays). The mitogenic effects of R1881, a non-metabolizable androgen that potently induces LNCaP cell proliferation, was completely blocked by greater than 0.5 microM 4-HPR. Furthermore, increasing the R1881 concentration in the presence of 2.0 microM 4-HPR increased apoptotic cell death. 4-HPR decreased prostate-specific antigen (PSA) protein levels in conditioned medium and decreased PSA mRNA expression. 4-HPR also decreased the ratio of bcl-2 to bax mRNA expression in LNCaP cells by approximately 45%, indicating that the apoptotic effects of 4-HPR may be mediated, at least in part, by alterations in the bcl-2/bax-regulated apoptotic pathway. N-acetylcysteine (4 mM) completely blocked the anti-proliferative and apoptotic-inducing effects of 4-HPR, suggesting that an oxidative mechanism may be involved. We concluded that (i) 4-HPR exerts growth-suppressive and apoptotic effects on LNCaP cells, (ii) 4-HPR can interact with androgen to suppress proliferation and induce apoptosis, (iii) the apoptotic effects of 4-HPR may be mediated in part by the bcl-2/bax pathway, and (iv) a pro-oxidant mechanism may contribute to the anti-proliferative and apoptotic-inducing effects of 4-HPR.

A simple program to calculate codon bias index

A computer program (PCBI) was developed to quickly calculate codon bias index (CBI). PCBI can analyze a gene containing introns. The 22 preferred codons defined from Saccharomyces cerevisiae were used in PCBI as the standard to measure the CBI values. However, users can modify the preferred codons to suit each organism. The data PCBI provides include DNA sequence of open reading frame without introns, amino acid sequence of gene product, a table of amino acid composition, a table of codon usage and (G + C) content, parameters for calculating CBI, and the value of CBI. PCBI runs on a DOS or Windows environment, but results can be saved in ASCII text format.

Molecular mechanism(s) of action of norepinephrine on the expression of the angiotensinogen gene in opossum kidney cells

BACKGROUND

Norepinephrine (NE) is the major endogenous neurotransmitter of the renal sympathetic nerves interacting with both the alpha- and beta-adrenoceptors in the renal proximal tubules. We have previously reported that isoproterenol and iodoclonidine stimulate the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells via the beta1-adrenoceptor and alpha2-adrenoceptor, respectively. We hypothesized that NE may interact with the beta- and/or alpha2-adrenoceptors to stimulate the expression of the ANG gene in OK cells.

METHODS

The fusion genes containing the various lengths of the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter were stably transfected into the OK cells. The stimulatory effect of NE on the expression of the fusion genes was evaluated by the amount of immunoreactive hGH (IR-hGH) secreted into the culture medium.

RESULTS

The addition of NE stimulated the expression of the fusion gene, pOGH (ANG N-1498/+18) in a dose-dependent manner. The stimulatory effect of NE was inhibited in the presence of propranolol, atenolol, Rp-cAMP, yohimbine, staurosporine, H-7 and U73122 but not in the presence of ICI 118,551 and prazosin. The addition of a combination of isoproterenol and iodoclonidine synergistically stimulated the expression of pOGH (ANG N-1498/+18) as compared to the addition of isoproterenol and iodoclonidine alone. Furthermore, the addition of NE, forskolin, 8-Br-cAMP or phorbol 12-myristate (PMA) stimulated the expression of pOGH (ANG N-806/-779/-53/+18), a fusion gene containing the putative cAMP responsive element (CRE, ANG N-806/-779) upstream of the ANG promoter (ANG N-53/+ 18) in OK 95 cells, but had no effect on the expression of fusion genes containing the mutant of the CRE.

CONCLUSION

These studies demonstrate that the stimulatory effect of NE on the expression of the ANG gene in OK cells may be mediated via both the beta1- and alpha2-adrenoceptors and via the CRE (ANG N-806/-779) in the 5'flanking region of rat ANG gene.

Effect of curcumin on the aryl hydrocarbon receptor and cytochrome P450 1A1 in MCF-7 human breast carcinoma cells

We examined the interaction of curcumin, a dietary constituent and chemopreventive compound, with the carcinogen activation pathway mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 mammary epithelial carcinoma cells. Curcumin caused a rapid accumulation of cytochrome P450 1A1 (CYP1A1) mRNA in a time- and concentration-dependent manner, and CYP1A1 monooxygenase activity increased as measured by ethoxyresorufin-O-deethylation. Curcumin activated the DNA-binding capacity of the AhR for the xenobiotic responsive element of CYP1A1 as measured by the electrophoretic-mobility shift assay (EMSA). Curcumin was able to compete with the prototypical AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin for binding to the AhR in isolated MCF-7 cytosol, indicating that it interacts directly with the receptor. Although curcumin could activate the AhR on its own, it partially inhibited the activation of AhR, as measured by EMSA, and partially decreased the accumulation of CYP1A1 mRNA caused by the mammary carcinogen dimethylbenzanthracene (DMBA). Curcumin competitively inhibited CYP1A1 activity in DMBA-treated cells and in microsomes isolated from DMBA-treated cells. Curcumin also inhibited the metabolic activation of DMBA, as measured by the formation of DMBA-DNA adducts, and decreased DMBA-induced cytotoxicity. These results suggest that the chemopreventive effect of curcumin may be due, in part, to its ability to compete with aryl hydrocarbons for both the AhR and CYP1A1. Curcumin may thus be a natural ligand and substrate of the AhR pathway.

Diosmin and diosmetin are agonists of the aryl hydrocarbon receptor that differentially affect cytochrome P450 1A1 activity

We investigated the effect of the chemopreventive compound diosmin and its aglycone form, diosmetin, on the carcinogen activation pathway mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 human breast epithelial cancer cells. Treatment of the cells with diosmin caused a dose-dependent increase in the metabolism of the mammary carcinogen 7,12-dimethylbenz(a)anthracene (DMBA), as assessed by increased formation of DMBA-DNA adducts and by DMBA-induced cytotoxicity. In contrast, treatment of the cells with diosmetin decreased both parameters. Diosmetin, but not diosmin, directly inhibited cytochrome P450 1A1 (CYP1A1) activity in a noncompetitive manner in microsomes isolated from DMBA-treated cells, as assayed by ethyoxyresorufin-O-deethylase activity. Treatment of the cells with diosmin or diosmetin, on the other hand, caused a dose- and time-dependent increase in CYP1A1 activity in intact cells that was comparable to that induced by DMBA or by the aryl hydrocarbon benzo(a)pyrene. Both diosmin and diosmetin caused an increase in the transcription of the CYP1A1 gene, as measured by increased levels of CYP1A1 mRNA. Both compounds caused the activation of the DNA-binding capacity of the AhR for the xenobiotic-responsive element of CYP1A1. These results indicate that diosmin and diosmetin are natural dietary agonists of the AhR, causing a potent increase in CYP1A1 transcription and CYP1A1 activity; however, only diosmetin is capable of inhibiting CYP1A1 enzyme activity, thus inhibiting carcinogen activation.

Differential effect of genistein on transforming growth factor beta 1 expression in normal and malignant mammary epithelial cells

Our present study demonstrates that the isoflavone genistein exerts a differential response in normal and malignant breast epithelial cells. The addition of genistein results in a dose-dependent increase in TGF-beta 1 mRNA expression in normal human mammary epithelial cells (HMEC) but not in tumor-derived MCF-7 cells. Genistein inhibits the growth and also causes an increase in apoptosis of HMEC. The increased expression of TGF-beta 1 may contribute to the growth inhibitory as well as apoptotic effects of genistein on HMEC.

Concomitant alterations in distribution of 70 kDa heat shock proteins, cytoskeleton and organelles in heat shocked 9L cells

Maintenance of cell architecture and positioning of organelles are major functions of the cytoskeleton. On the other hand, induction of heat shock proteins (HSPs) and reorganization of the cytoskeleton are the most significant changes in heat-shocked mammalian cells. We examine the alterations in HSP70 and its constitutively expressed cognate, HSC70, as well as the cytoskeleton and organelles in 9L rat brain tumor cells upon heat shock. We employed fluorescence microscopy and scanning electron microscopy to follow these changes. Levels of HSP70s were quantified by Western blotting. Accumulation of HSC70 was more transient and the protein translocated to and subsequently exited from the nucleus more rapidly than HSP70. Changes in actin microfilaments include the nuclear localization of actin fraction and disappearance of cytoplasmic microfilament bundles, while the cortical actin microfilaments were almost unaffected. Furthermore, microtubules retracted slightly from the cell periphery but remained largely unchanged. In contrast, the intermediate filaments collapsed into the perinuclear region. The mitochondria converted from filamentous into granular forms and clustered in a region overlapping with the collapsed intermediate filaments. All of the above alterations are reversible and largely reverted after 8 h of recovery. The effect on Golgi organization was very transient and the apparatus assumed a normal appearance within 4 h after the heat treatment. The ER, on the other hand, was totally unaffected by the heat treatment. These observations help correlate the sequential events following a stress like heat shock and suggest possible physiological functions of these essential constituents of a cell under stress.

Increased UDP-glucuronosyltransferase activity and decreased prostate specific antigen production by biochanin A in prostate cancer cells

Our laboratory has characterized androgen metabolism in an androgen-responsive prostate cancer cell line (LNCaP) and showed that these cells accumulated intracellular testosterone primarily as glucuronidated metabolites. Using a cell-free assay with testosterone as substrate, we showed that LNCaP had UDP-glucuronosyltransferase (UDPGT) activity. Because dietary factors, such as flavonoids in soy products, may reduce the risk for hormone-dependent cancers, we studied the effects of flavonoids on testosterone-UDPGT activity. LNCaP cells were exposed to selected flavonoids for up to 6 days. The increase in UDPGT-specific activity was linear over this period. Of the compounds tested, biochanin A was the most potent, with increased activity at concentration range 0.5-50 microM. Activities were linear for time and protein and were unaffected by flavonoids added directly to the assay. Kinetics studies showed no change in Km for testosterone in the face of these large increases in specific activity. Cellular metabolism of testosterone reflected the increase in enzyme activity. Intact cells treated with biochanin A produced testosterone-glucuronide from testosterone at twice the rate of controls. The steroid form of the UDPGT transcript was expressed in LNCaP cells and was enhanced in biochanin A-treated LNCaP cells. Additionally, biochanin A markedly decreased prostate specific antigen (PSA) level against the effect of testosterone on PSA production. Biochanin A significantly decreased the testosterone-stimulated release of PSA, presumably because biochanin A increased UDPGT and increased the intracellular glucuronidation of testosterone. These studies suggest that the modulation of hormone metabolism by dietary factors may be important in the prevention and treatment of prostate cancer.

Regulation of death promoter Bak expression by cell density and 17 beta-estradiol in MCF-7 cells

In the current study we examined the regulation of Bak, a death promoter of an apoptotic pathway, in the human breast cancer cell line MCF-7. We observed a time-dependent increase in both Bak mRNA and protein levels which appeared to correlate well with the increase in cell density. We also found that treatment of cells with 17beta-estradiol resulted in inhibition of the time-dependent increases in Bak mRNA and protein. The effects of estradiol appeared to be via estrogen receptor as treatment of cells with progesterone did not effect Bak expression. Our study provides additional molecular evidence for (1) a link between apoptosis pathways and cell-cell and/or cell-cell matrix interactions and (2) a role for estradiol in the modulation of signals between apoptosis pathways and cell-cell and/or cell-cell matrix interactions.

Effect of glucose on the expression of the angiotensinogen gene in opossum kidney cells

To investigate whether D(+)-glucose has a stimulatory effect on the expression of the angiotensinogen (Ang) gene in opossum kidney (OK) cells, we used OK cells with a fusion gene containing various lengths of the 5'-flanking regulatory sequence of the rat Ang gene fused with the human growth hormone (hGH) gene as a reporter, stably integrated into their genomes. The level of expression of the fusion gene was quantified by the amount of immunoreactive-human growth hormone (IR-hGH) secreted into the medium. The addition of D(+)-glucose stimulated the expression of pOGH (Ang N-1498/+18) in OK 27 cells in a dose-dependent manner (5 to 25 mM), whereas the addition of D-mannitol, L-glucose and 2-deoxy-D-glucose (25 mM) had no effect. The stimulatory effect of D(+)-glucose (25 mM) was blocked by the presence of staurosporine or H7 (an inhibitor of protein kinase C) or U73122 (an inhibitor of phospholipase C and A2) but not blocked by the presence of Rp-cAMP (an inhibitor of cAMP-dependent protein kinase A). The addition of D(+)-glucose (25 mM) also stimulated the expression of pOGH (Ang N-960/+18) and pOGH (Ang N-688/+18) in OK 960 and OK 688 cells, respectively. It had no stimulatory effect, however, on the expression of pOGH (Ang N-280/+18) and pOGH (Ang N-35/+18) in OK 280 and OK 35 cells, respectively. The addition of D(+)-glucose also had no effect on the expression of pTKGH in OK 13 cells, an OK cell line, into which had been stably integrated a fusion gene, pTKGH containing the promoter/enhancer DNA sequence of the viral thymidine-kinase (TK) gene fused with a human growth hormone gene as a reporter. These studies demonstrate that the stimulatory effect of high D(+)-glucose concentration (25 mM) on the expression of the angiotensinogen-growth hormone fusion genes in OK cells is mediated via the 5'-flanking region of the angiotensinogen gene and the protein kinase C signal transduction pathway. Our data indicate that a high glucose concentration may activate the renin-angiotensin system in the renal proximal tubular cells.

Differential effects of dietary phyto-oestrogens daidzein and equol on human breast cancer MCF-7 cells

The in vitro effects of two closely related phyto-oestrogens daidzein and equol on the oestrogen receptor positive human breast cancer cells MCF-7 were examined. There is differential metabolism of daidzein in humans, and the conversion of daidzein to equol by intestinal microbes occurs only in 30% of the population. The differential potency of these two compounds is thus of considerable importance since it may be likely that the relative risk of hormone-dependent cancers may be higher in 'non-responders'. In the present study, we compared the ability of both these compounds to induce mRNA expression of the oestrogen-responsive pS2 gene, to compete with oestradiol for binding to the oestrogen receptor (ER) and to affect cellular proliferation. Our studies demonstrate that equol is a 100-fold more potent than daidzein in stimulating an oestrogenic response. Equol was also more effective than daidzein in competing with 3H-oestradiol for binding to the ER. These results suggest that equol has a higher affinity for the ER. Both compounds stimulated the growth of MCF-7 cells in a concentration-dependent manner (10(-8)-10(-5)M). Although equol exhibits oestrogenic activity, exposure of MCF-7 cells to equol simultaneously with oestradiol was effective in reducing pS2 mRNA expression. This was not observed with daidzein. However, long-term exposure of MCF-7 cells to both daidzein and equol resulted in the downregulation of ER mRNA expression.

Plasmids in Lactobacillus

This review describes Lactobacillus plasmids on distribution, structure, function, vector construction, vector stability, application, and prospective. About 38% of species of the genus Lactobacillus were found to contain plasmids with different sizes (from 1.2 to 150 kb) and varied numbers (1 or more). Some Lactobacillus plasmids with small sizes were highly similar to those of single strand plasmids from other Gram-positive bacteria. The extensive sequence homologies of plus origins, replication initiation proteins, minus origins, cointegration sites, and the presence of single strand intermediates supported the fact that these small Lactobacillus plasmids replicate with a rolling-circle replication mechanism. Some Lactobacillus plasmid replicons were of broad host range that could function in other Gram-positive bacteria, and even in Escherichia coli, while replicons of other Gram-positive bacteria also function in Lactobacillus. Although most Lactobacillus plasmids are cryptic, some plasmid-encoded functions have been discovered and applied to vector construction and Lactobacillus identification, detection, and modification.

Angiotensinogen gene expression is stimulated by the cAMP-responsive element binding protein in opossum kidney cells

It has been reported previously that the addition of isoproterenol or forskolin stimulates the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) 27 cells, an OK cell line with a fusion gene containing the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (ANG N-1498/+18), permanently integrated into their genomes. To investigate whether the effect of isoproterenol or forskolin on the expression of the ANG gene is mediated via the nuclear 43-kD cAMP-responsive element binding protein (CREB), OK 27 cells were transiently transfected with an expression plasmid containing the cDNA for the 43-kD CREB (pRSV/CREB). The level of expression of the pOGH (ANG N-1498/+18) in OK 27 cells was estimated by the amount of immunoreactive hGH secreted into the culture medium. Transfection of pRSV/CREB alone stimulated the expression of pOGH (ANG N-1498/+18). The addition of isoproterenol or forskolin further enhanced the stimulatory effect of pRSV/ CREB on the expression of pOGH (ANG N-1498/+18). The enhancing effect of isoproterenol was inhibited by the presence of propranolol (an inhibitor of beta-adrenoceptors) and (R)-p-adenosine 3'5'-cyclic monophospho-orthioate (Rp)-cAMP (an inhibitor of cAMP-dependent protein kinase A I and II). Transfection of pRSV/CREB had no effect on the expression of thymidine kinase growth hormone in OK 13 cells, an OK cell line with a fusion gene containing the promoter/enhancer DNA sequence of the viral thymidine-kinase gene fused with an hGH gene as a reporter, thymidine kinase growth hormone, permanently integrated into their genomes. These studies demonstrate that isoproterenol stimulates the expression of ANG gene via the cAMP-dependent protein kinase A and probably via the interaction of the 43-kD CREB with the 5'-flanking region of the ANG gene. Our data indicate that the nuclear 43-kD CREB may have a modulatory role on the expression of the ANG gene in OK cells.

Effects of dehydroepiandrosterone and calorie restriction on the Bcl-2/Bax-mediated apoptotic pathway in p53-deficient mice

Modulation of apoptosis through altered expression of Bcl-2 and/or Bax may be a mechanism by which dehydroepiandrosterone (DHEA) administration and calorie restriction (CR) exert their chemopreventive effects in p53-deficient (p53-/-) mice. Using immunohistochemical detection we found that treatment with both DHEA and CR resulted in decreased expression of the PCNA proliferation marker in the thymus. In addition, treatment with DHEA also increased the rate of apoptosis in the thymus, resulting in marked thymic atrophy. Thus, both DHEA and CR appear to shift cell number homeostasis by favoring apoptosis. To further understand the molecular mechanisms by which DHEA and CR exert their effects, we examined two components of the apoptotic pathway, Bcl-2 and Bax. We found that p53-/- mice have much higher levels of Bcl-2 mRNA in the thymus than wild-type (p53+/+) mice. Treatment of p53-/- animals with DHEA resulted in decreased Bcl-2 but not Bax mRNA levels in the thymus. In contrast, CR did not change either Bcl-2 or Bax mRNA expression. The present study provides molecular evidence that DHEA and CR may modulate tumorigenesis through alterations in the apoptotic and/or proliferative pathways.

Effect of N-(4-hydroxyphenyl)retinamide on apoptosis in human breast cancer cells

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) has been used in breast cancer prevention and treatment. However, the molecular mechanisms mediating the effects of 4-HPR remain elusive. In the present study, we examined the effects of 4-HPR on components of apoptosis pathway (i.e Bcl-2 and Bax) and apoptotic death in both estrogen receptor-positive and estrogen receptor-negative cell lines. We found that: (1) 4-HPR treatment resulted in decreased Bcl-2 mRNA but not Bax mRNA levels; (2) the effect of 4-HPR on Bcl-2 mRNA level was different from other retinoids; (3) 4-HPR treatment induced apoptosis in both estrogen receptor-positive and -negative cells. Hence, the breast cancer chemopreventive properties of 4-HPR may involve modulation of apoptosis pathways.

Dopaminergic receptors and angiotensinogen gene expression in opossum kidney cells

To investigate whether expression of the renal angiotensinogen gene is regulated by dopaminergic receptors, we used opossum kidney (OK 27) cells with a fusion gene containing the 5'- flanking regulatory sequence of the rat angiotensinogen gene fused with a human growth hormone (hGH) gene as a reporter [pOGH, angiotensinogen nucleotide (N) -1498/+18], permanently integrated into their genomes. The level of expression of pOGH (angiotensinogen N-1498/+18) in OK 27 was evaluated by the amount of immunoreactive hGH (ir-hGH) secreted into the culture medium. In the absence of 3-isobutyl-1-methylxanthine (IBMX), addition of dopamine (10(-13) to 10(-5)M) had minimal effect on the expression of the pOGH (angiotensinogen N-1498/+18) in OK 27 cells. In the presence of IBMX, addition of low concentrations (10(-13) and 10(-7) M) of dopamine stimulated the expression of pOGH angiotensinogen N-1498/+18) in OK 27 cells in a dose-dependent manner, whereas high concentrations (i.e., > 10(-7) M) had minimal effect. The stimulatory effect of dopamine on the expression of pOGH (angiotensinogen N-1498/+18) was inhibited by the presence of SCH-23390 (D1-dopaminergic receptor antagonist) and spiperone (D2-dopaminergic receptor antagonist), but not by ketanserin (5 HT2/5HT1c-serotonergic receptor antagonist). Moreover, the stimulatory effect of dopamine was inhibited by the presence of U-73122 (an inhibitor of phospholipase C and phospholipase A2) or staurosporine (an inhibitor of protein kinase C) or (R)-p-adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMP[S]; an inhibitor of cAMP-dependent protein kinase AI and II). Addition of low concentrations (10(-13) to 10(-9)M) of SKF-82958 (D1-dopaminergic receptor agonist) or PPHT (D2-dopaminergic receptor agonist) also stimulated the expression of pOGH (angiotensinogen N-1498/+18). The stimulatory effect of SKF-82958 was inhibited by the presence of SCH-23390 or Rp-cAMP[S], whereas the effect of PPHT was inhibited by the presence of spiperone or staurosporine. These studies demonstrate that the expression of pOGH (angiotensinogen N-1498/+18) in OK 27 cells is modulated by dopaminergic receptor agonists.

beta-Adrenoceptors and dexamethasone synergistically stimulate the expression of the angiotensinogen gene in opossum kidney cells

We transiently co-transfected opossom kidney (OK) cells with the plasmid containing the cDNA for beta 1-adrenoceptor (pBC-beta 1 AR) or beta 2-adrenoceptor (pBC-beta 2 AR) and a fusion gene with the 5'-flanking region of the angiotensinogen (ANG) gene linked to a bacterial chloramphenicol acetyl transferase (CAT) coding sequence as a reporter, pOCAT (ANG N-1498/ +18). Co-transfection of plasmid pBC-beta 1 AR or pBC-beta 2 AR alone enhanced the expression of pOCAT (ANG N-1498/+18). The addition of isoproterenol further stimulated the expression of pOCAT (ANG N-1498/ +18) when co-transfected with pBC-beta 1AR, but not with pBC-beta 2AR. Moreover, the addition of a combination of dexamethasone and isoproterenol synergistically stimulated the expression of pOCAT (ANG N-1498/+18) when co-transfected with pBC-beta 1AR, but not when cotransfected with pBC-beta 2AR. The synergistic effect of dexamethasone and isoproterenol was inhibited by the presence of RU 486 (an antagonist of glucocorticoid) or Rp-cAMP (an inhibitor of cAMP-dependent protein kinase A I and II). To localize the putative cAMP-responsive element (CRE) and glucocorticoid responsive element (GRE) in the ANG gene, we constructed the fusion gene by inserting the DNA fragment, ANG N-806 to N-465 upstream of the thymidine kinase (TK) promoter fused to a CAT gene and introduced them with pBC-beta 1AR into OK cells. The addition of dexamethasone or isoproterenol alone stimulated the expression of pTKCAT (ANG N-806/-465). The addition of isoproterenol and dexamethasone synergistically stimulated the transcriptional activity of pTKCAT (N-806/-465). These studies demonstrate that the beta 1-adrenoceptor and dexamethasone act synergistically to stimulate the expression of the ANG gene in OK cells via the putative CRE and GREs in the 5'-flanking region of the rat ANG gene. These data should aid in the understanding of the molecular mechanism(s) of the stimulatory effect of catecholamines/glucocorticoid induced expression of the ANG gene in the kidney.

Molecular effects of genistein on estrogen receptor mediated pathways

Genistein, a component of soy products, may play a role in the prevention of breast and prostate cancer. However, little is known about the molecular mechanisms involved. In the present study, we examined the effects of genistein on the estrogen receptor positive human breast cancer cell line MCF-7. We observed that genistein stimulated estrogen-responsive pS2 mRNA expression at concentrations as low as 10(-8) M and these effects can be inhibited by tamoxifen. We also showed that genistein competed with [3H]estradiol binding to the estrogen receptor with 50% inhibition at 5 x 10(-7) M. Thus, the estrogenic effect of genistein would appear to be a result of an interaction with the estrogen receptor. The effect of genistein on growth of MCF-7 cells was also examined. Genistein produced a concentration-dependent effect on the growth of MCF-7 cells. At lower concentrations (10(-8)-10(-6) M) genistein stimulated growth, but at higher concentrations (> 10(-5) M) genistein inhibited growth. The effects of genistein on growth at lower concentrations appeared to be via the estrogen receptor pathway, while the effects at higher concentrations were independent of the estrogen receptor. We also found that genistein, though estrogenic, can interfere with the effects of estradiol. In addition, prolonged exposure to genistein resulted in a decrease in estrogen receptor mRNA level as well as a decreased response to stimulation by estradiol.

Alpha-adrenoceptors and angiotensinogen gene expression in opossum kidney cells

To investigate whether alpha (alpha)-adrenoceptor agonists have a stimulatory effect on the expression of the angiotensinogen (Ang) gene in opossum kidney (OK) cells, we used OK 27 cells with a fusion gene containing the 5'-flanking regulatory sequence of the rat angiotensinogen gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (Ang N-1498/+18), permanently integrated into their genomes. The level of expression of the pOGH (Ang N-1498/+18) was quantitated by the amount of immunoreactive-human growth hormone (IR-hGH) secreted into the medium. The addition of iodoclonidine (alpha 2-adrenoceptor agonist, 10(-13) to 10(-9) M) and phorbol 12-myristate 13-acetate (PMA, 10(-13) to 10(-5) M) stimulated the expression of pOGH (Ang N-1498/+18) in a dose-dependent manner, whereas the addition of phenylephrine (alpha 1-adrenoceptor agonist, 10(-13) to 10(-5) M) had no effect. The stimulatory effect of iodoclonidine was blocked by the presence of yohimbine (alpha 2-adrenoceptor antagonist) and staurosporine (an inhibitor of protein kinase C) but not blocked by the presence of prazosin (alpha 1-adrenoceptor antagonist) or Rp-cAMP (an inhibitor of cAMP-dependent protein kinase A). The addition of iodoclonidine, phenylephrine or PMA had no effect on the expression of pTKGH in OK 13 cells, an OK cell line, into which had been stably integrated a fusion gene, pTKGH containing the promoter/enhancer DNA sequence of the viral thymidine-kinase (TK) gene fused with a human growth hormone gene as a reporter.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of estrogen on apoptotic pathways in human breast cancer cell line MCF-7

We utilized a reverse transcription-PCR method to examine the effect of estrogen on the expression of mRNA for Bcl-2 and Bax, two modulatory proteins in the apoptotic pathway, in human breast cancer cell line MCF-7. We found that the bcl-2 mRNA levels in the cells exposed to 17 beta-estradiol were higher than those of control cells. Although the relative bax mRNA levels remained unchanged, the changes in bcl-2 mRNA level occurred in a time- and concentration-dependent fashion. In addition, pretreatment with 17 beta-estradiol protected MCF-7 cells from apoptosis. Our study provides evidence that responses of breast epithelial cells toward a steroid sex hormone involve regulation of the apoptotic pathway.

Investigation of the active site cysteine residue of rat liver mitochondrial aldehyde dehydrogenase by site-directed mutagenesis

To determine the active site cysteine residue in aldehyde dehydrogenase, we mutated amino acid residues 49, 162, and 302 of recombinantly expressed rat liver mitochondrial (class 2) aldehyde dehydrogenase. The C49A and C162A mutants were fully active tetrameric enzymes, although the C162A mutant was found to be highly unstable. The C302A mutant was also a tetramer and bound coenzyme, but lacked both dehydrogenase and esterase activities. To test for the role of cysteine 302 as a nucleophile, the residue was mutated to a serine, a poor nucleophile. this C302S mutant was active but was a much poorer catalyst, with a kcat/Km value 7 x 10(5) times lower than that of the recombinant native enzyme. Unlike with native enzyme where deacylation is rate limiting, formation of the serine hemiacetal intermediate appeared to be the rate-limiting step. Cysteine 302 is the only strictly conserved cysteine residue among all the available sequences of the aldehyde dehydrogenase superfamily, supporting the role of this residue as the active site nucleophile of aldehyde dehydrogenase.

Expression of the angiotensinogen gene is synergistically stimulated by 8-BrcAMP and Dex in opossum kidney cells

We transiently transfected fusion genes with the 5'-flanking region of the angiotensinogen gene linked to a bacterial chloramphenicol acetyltransferase (CAT) coding sequence as a reporter into opossum kidney (OK) cells. The addition of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) (10(-3)-10(-7) M) or forskolin (10(-9)-10(-5) M) stimulated the expression of the plasmid pOCAT [angiotensinogen nucleotide (N) -1498/+18] fusion gene in OK cells in a dose-dependent manner. The addition of dexamethasone (Dex) (10(-6) M) further enhanced the stimulatory effect of 8-BrcAMP or forskolin, whereas the addition of (R)-p-adenosine 3',5'-cyclic monophosphorothioate [(Rp)-cAMP[S], an inhibitor of cAMP-dependent protein kinase A, I and II] blocked the stimulatory effect of 8-BrcAMP. Furthermore, the addition of 8-BrcAMP (10(-3) M) or Dex (10(-6) M) or a combination of both stimulated the expression of pOCAT (angiotensinogen N -1138/+18), pOCAT (angiotensinogen N -960/+18), pOCAT (angiotensinogen N -814/+18), and pOCAT (angiotensinogen N -688/+18), but had no effect on the expression of pOCAT (angiotensinogen N -280/+18), pOCAT (angiotensinogen N -198/+18), pOCAT (angiotensinogen N -110/+18), pOCAT (angiotensinogen N -53/+18), and pOCAT (angiotensinogen N -35/+18). To further localize the putative cAMP-responsive element (CRE) in the angiotensinogen gene, we constructed fusion genes by inserting the DNA fragments angiotensinogen N -814 to N -689, angiotensinogen N -814 to N -761, and angiotensinogen N -760 to N -689 of the 5'-flanking region of the angiotensinogen gene upstream of the thymidine kinase (TK) promoter fused to a CAT gene and introduced them into OK cells.(ABSTRACT TRUNCATED AT 250 WORDS)