Purification and characterization of chitosanase and Exo-beta-D-glucosaminidase from a Koji mold, Aspergillus oryzae IAM2660

Chitosan-degrading activity was detected in the culture fluid of Aspergillus oryzae, A. sojae, and A. flavus among various fungal strains belonging to the genus Aspergillus. One of the strong producers, A. oryzae IAM2660 had a higher level of chitosanolytic activity when N-acetylglucosamine (GlcNAc) was used as a carbon source. Two chitosanolytic enzymes, 40 kDa and 135 kDa in molecular masses, were purified from the culture fluid of A. oryzae IAM2660. Viscosimetric assay and an analysis of reaction products by thin-layer chromatography clearly indicated the endo- and exo-type cleavage manner for the 40-kDa and 135-kDa enzymes, respectively. The 40-kDa enzyme, designated chitosanase, catalyzed a hydrolysis of glucosamine (GlcN) oligomers larger than pentamer, glycol chitosan, and chitosan with a low degree of acetylation (0-30%). The 135-kDa exo-beta-D-glucosaminidase,enzyme,named released a single GlcN residue from the GlcN oligomers and chitosan, but did not release GlcNAc residues from either GlcNAc oligomer or colloidal chitin.

4-[3-(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)phenyl]benzoic acid and heterocyclic-bridged analogues are novel retinoic acid receptor subtype and retinoid X receptor alpha agonists

Aromatic retinoids having a meta-substituted aromatic ring bridge, such as 4-[3-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)phenyl]benzo ic acid and its 3,5-diaryl-substituted 4,5-dihydroisoxazole analogue, function as retinoid receptor panagonists by activating both retinoic acid and retinoid X receptors to induce gene transcription, and thereby provide novel scaffolds for retinoid drug development. Both classes of these ligand-inducible transcription factors are involved in mediating the inhibitory effects of retinoids on cancer cell growth.

sp2-bridged diaryl retinoids: effects of bridge-region substitution on retinoid X receptor (RXR) selectivity

RXR class selectivity and RXR transcriptional activation activity compared to those for the retinoic acid receptor subtypes were enhanced on the 4-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenylethenyl)be nzoic acid scaffold and its 3-methyl analogue by replacing their 1,1-ethenyl bridge by a 1,1-(2-methylpropenyl) or cyclopropylidenylmethylene group.

Induction of differentiation by 1alpha-hydroxyvitamin D(5) in T47D human breast cancer cells and its interaction with vitamin D receptors

The role of the active metabolite of vitamin D, 1,25 dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), in cell differentiation is well established. However, its use as a differentiating agent in a clinical setting is precluded due to its hypercalcaemic activity. Recently, we synthesised a relatively non-calcaemic analogue of vitamin D(5), 1alpha-hydroxyvitamin D(5) (1alpha(OH)D(5)), which inhibited the development of carcinogen-induced mammary lesions in culture and suppressed the incidence of chemically induced mammary carcinogmas in rats. In the present study, we determined the differentiating effects of 1alpha-(OH)D(5) in T47D human breast cancer cells and compared its effects with 1,25(OH)(2)D(3). Cells incubated with either 10 or 100 nM of the analogues inhibited cell proliferation in a dose-dependent manner, as measured by the dimethylthiazolyl-2,5-diphenyltetrazolium bromide (MTT) assay. Similar growth-inhibitory effects were also observed for MCF10(neo) cells. Both vitamin D analogues induced cell differentiation, as determined by induction of casein expression and lipid production. However, MCF10(neo) cells failed to respond to either vitamin D analogue and did not undergo cell differentiation. Since the cell differentiating effect of vitamin D is considered to be mediated via the vitamin D receptor (VDR), we examined the induction of VDR using reverse transcriptase-polymerase chain reaction (RT-PCR) in both cells. The results showed that, in T47D cells, both 1,25(OH)(2)D(3) and 1alpha(OH)D(5) induced VDR in a dose-dependent manner. Moreover, both analogues of vitamin D upregulated the expression of vitamin D response element-chloramphenicol acetyl transferase (VDRE-CAT). These results collectively indicate that 1alpha-(OH)D(5) may mediate its cell-differentiating action via VDR in a manner similar to that of 1,25(OH)(2)D(3).

Orphan receptor COUP-TF is required for induction of retinoic acid receptor beta, growth inhibition, and apoptosis by retinoic acid in cancer cells

Retinoic acid receptor beta (RARbeta) plays a critical role in mediating the anticancer effects of retinoids. Expression of RARbeta is highly induced by retinoic acid (RA) through a RA response element (betaRARE) that is activated by heterodimers of RARs and retinoid X receptors (RXRs). However, RARbeta induction is often lost in cancer cells despite expression of RARs and RXRs. In this study, we provide evidence that orphan receptor COUP-TF is required for induction of RARbeta expression, growth inhibition, and apoptosis by RA in cancer cells. Expression of COUP-TF correlates with RARbeta induction in a variety of cancer cell lines. In addition, stable expression of COUP-TF in COUP-TF-negative cancer cells restores induction of RARbeta expression, growth inhibition, and apoptosis by RA, whereas inhibition of COUP-TF by expression of COUP-TF antisense RNA represses the RA effects. In a transient transfection assay, COUP-TF strongly induced transcriptional activity of the RARbeta promoter in a RA- and RARalpha-dependent manner. By mutation analysis, we demonstrate that the effect of COUP-TF requires its binding to a DR-8 element present in the RARbeta promoter. The binding of COUP-TF to the DR-8 element synergistically increases the RA-dependent RARalpha transactivation function by enhancing the interaction of RARalpha with its coactivator CREB binding protein. These results demonstrate that COUP-TF, by serving as an accessory protein for RARalpha to induce RARbeta expression, plays a critical role in regulating the anticancer activities of retinoids.

[Development of a multi-channel physiological telemetry system]

OBJECTIVE

To develop an instrument used in measurement of physiological parameters in laboratories or field. Method A: computer was used to process data in the telemetry system. The frequency-time division modulation technique was adopted. The low frequency signals were directly connected to the computer serial port after demodulation, and measurement control was achieved by single-chip computer. Temperature measurement results were obtained by conversion table.

RESULT

It is capable of telemeter and processing ECG, wind speed and temperature signals in real-time. Good results were gained in high temperature condition and -17 degrees C environment.

CONCLUSION

The instrument has many advantages, such as high accuracy, good processing ability, reliability, long operation distance, small volume and easy operation.

Resistance of HBL100 human breast epithelial cells to vitamin D action

Vitamin D analogs are effective inhibitors of breast cancer cell growth, but many breast cancer cell lines show various degrees of resistance to the growth inhibitory effect of vitamin D. In this study, we investigated the mechanism of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] resistance of the human breast epithelial cell line HBL100, which had been immortalized by Simian virus 40 (SV40) large T antigen. We determined the expression, DNA binding and transactivation activity of vitamin D3 receptor (VDR) in HBL100 and a vitamin D-sensitive ZR75-1 breast cancer cell line. Western blot analysis revealed a comparable expression of VDR gene in both cell lines. However, gel retardation assays demonstrated nuclear proteins from ZR75-1 cells but not from HBL100; cells expressed a 9-fold increase in the binding activity with a vitamin D response element (VDRE). Using a transient transfection assay, we showed that the VDRE was activated by 8-fold in ZR75-1. However, in HBL100 cells there was no activation observed in response to 1,25(OH)2D3. On the other hand, co-transfection of a VDR expression vector could restore 1,25(OH)2D3-induced VDRE transcription in HBL100 cells. Moreover, stable expression of VDR in HBL100 cells resulted in enhanced sensitivity of the cells to the growth inhibitory effect of 1,25(OH)2D3. Since CV-1 cells express very little endogenous VDR, the interactions of VDR and large T antigen were carried out in these cells. By transient co-transfection, we observed that expression of the large T antigen strongly inhibited 1,25(OH)2D3-induced VDRE transcriptional activity in a dose-dependent fashion in CV-1 cells. At 120 ng VDR concentration, the inhibition was completely reversed. Thus the loss of the growth inhibitory effect of vitamin D3 in HBL100 cells may be caused by the expression of the large T antigen in the cells, and provide further evidence that VDR is required for efficient growth inhibition by vitamin D3.

Effects of trans-retinoic acid, 9-cis-retinoic acid, 1alpha,25-(dihydroxy)vitamin D3 and a novel apoptosis-inducing retinoid on breast cancer and endothelial cell growth

Breast cancer cell growth inhibition was not synergistically enhanced by trans-retinoic acid (RA) or 9-cis-RA plus 1alpha,25-(dihydroxy)vitamin D3 (DHVD). The retinoid/DHVD combinations did lower their 50% effective concentrations for inhibiting retinoid-sensitive MCF-7, but not retinoid-refractory BT-20, breast cancer cell growth. In contrast, the synthetic retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid (AHPN) and its analog SR11389 inhibited the growth of both cell lines. Unlike RA, 9-cis-RA and DHVD, AHPN and SR11389 also potently inhibited human umbilical vascular endothelial cell growth. These results on AHPN and SR11389 suggest that angiogenesis of tumor microvasculature should also be an effective therapeutic target for this new compound class.

Molecular determinants of AHPN (CD437)-induced growth arrest and apoptosis in human lung cancer cell lines

6-[3-(1-Adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN or CD437), originally identified as a retinoic acid receptor gamma-selective retinoid, was previously shown to induce growth inhibition and apoptosis in human breast cancer cells. In this study, we investigated the role of AHPN/CD437 and its mechanism of action in human lung cancer cell lines. Our results demonstrated that AHPN/CD437 effectively inhibited lung cancer cell growth by inducing G0/G1 arrest and apoptosis, a process that is accompanied by rapid induction of c-Jun, nur77, and p21(WAF1/CIP1). In addition, we found that expression of p53 and Bcl-2 was differentially regulated by AHPN/CD437 in different lung cancer cell lines and may play a role in regulating AHPN/CD437-induced apoptotic process. On constitutive expression of the c-JunAla(63,73) protein, a dominant-negative inhibitor of c-Jun, in A549 cells, nur77 expression and apoptosis induction by AHPN/CD437 were impaired, whereas p21(WAF1/CIP1) induction and G0/G1 arrest were not affected. Furthermore, overexpression of antisense nur77 RNA in A549 and H460 lung cancer cell lines largely inhibited AHPN/CD437-induced apoptosis. Thus, expression of c-Jun and nur77 plays a critical role in AHPN/CD437-induced apoptosis. Together, our results reveal a novel pathway for retinoid-induced apoptosis and suggest that AHPN/CD437 or analogs may have a better therapeutic efficacy against lung cancer.

Interaction of BAG-1 with retinoic acid receptor and its inhibition of retinoic acid-induced apoptosis in cancer cells

BAG-1 (also known as RAP46) is an anti-apoptotic protein, which has been shown previously to interact with a number of nuclear hormone receptors, including receptors for glucocorticoid, estrogen, and thyroid hormone. We show here that BAG-1 also interacts with retinoic acid receptor (RAR). Gel retardation assays demonstrated that in vitro translated BAG-1 protein could effectively inhibit the binding of RAR but not retinoid X receptor (RXR) to a number of retinoic acid (RA) response elements (RAREs). A glutathione S-transferase-BAG-1 fusion protein also specifically bound RAR but not RXR. Interaction of BAG-1 and RAR could also be demonstrated by yeast two-hybrid assays. In transient transfection assays, co-transfection of BAG-1 expression plasmid inhibited the transactivation activity of RAR/RXR heterodimers but not RXR/RXR homodimers. When stably expressed in breast cancer cell lines, BAG-1 inhibited binding of RAR/RXR heterodimer to a number of RAREs and suppressed RA-induced growth inhibition and apoptosis. In addition, RA-induced suppression of Bcl-2 expression was abrogated by overexpression of BAG-1. These results demonstrate that BAG-1 can regulate retinoid activities through its interaction with RAR and suggest that elevated levels of BAG-1 protein could potentially contribute to retinoid resistance in cancer cells.

Regulation of RAR beta expression by RAR- and RXR-selective retinoids in human lung cancer cell lines: effect on growth inhibition and apoptosis induction

Retinoids regulate the growth and differentiation of human tracheobronchial epithelial cells. In this study, we investigated the effects of all-trans-retinoic acid (trans-RA) and receptor class-selective retinoids on the growth and apoptosis of human lung cancer cell lines. Trans-RA significantly inhibited the growth of Calu-6 and H460 cells, accompanied by induction of RA receptor (RAR) beta expression. In contrast, it had little effect on the growth of H292, SK-MES-1 and H661 lung cancer cell lines, in which RAR beta expression was not induced. Stable expression of RAR beta in RAR beta-negative, trans-RA-resistant SK-MES-1 and H661 lung cancer cells led to recovery of trans-RA-induced growth inhibition, which occurred, however, only at low serum concentration. Using fluorescent microscopy and the terminal deoxyribonucleotidyl transferase (TdT) assay, we demonstrated that induction of apoptosis by trans-RA contributed to its growth-inhibitory effect in trans-RA-sensitive lung cancer cell lines. Analysis of RAR-selective and retinoid X receptor (RXR)-selective retionoids showed that activation of both RARs and RXRs could induce growth inhibition in trans-RA-sensitive lung cancer cells. Also, an additive synergistic effect on growth inhibition and RAR beta induction was observed when cells were treated with combinations of RAR-selective and RXR-selective retinoids. Together, our results show that expression of RAR beta plays a role in mediating retinoid response in lung cancer cells and that activation of RARs or RXRs contributes to induction of RAR beta, growth inhibition and apoptosis by retinoids.

Breast cancer genome anatomy: correlation of morphological changes in breast carcinomas with expression of the novel gene product Di12

To determine which genes may be activated or inactivated during breast cancer development, we employed two cloning strategies (subtractive hybridization and differential display) using RNA samples from a human breast tumor and its matching normal breast cell line. Of 950 clones isolated, 102 cDNA inserts were analysed by DNA sequencing and database searching. We found 30 clones that were obviously unidentified, with no significant homology to any listed human gene. We focused upon one of the novel genes, Di12, that is differentially expressed as a 1.35 kb RNA in breast cancer tissues and cell-lines, and in several normal tissues. A full length cDNA of this gene was cloned, and its DNA sequence revealed an open reading frame of 339 amino acids. Antibodies to the ten N-terminal amino acids were developed to investigate the expression of Di12 in breast cancer cell-lines and tumors. The Di12 protein was found in tissue sections of infiltrating ductal carcinomas (IDCs), but not in benign or normal breast specimens. RT-PCR analysis confirmed expression of Di12 in 80% of infiltrating ductal carcinomas (IDCs). As IDC constitutes approximately 70% of breast cancers seen clinically, the level of Di12 expression may be predictive of disease progression.

Regulation of RAR beta expression by RAR- and RXR-selective retinoids in human lung cancer cell lines: effect on growth inhibition and apoptosis induction

Retinoids regulate the growth and differentiation of human tracheobronchial epithelial cells. In this study, we investigated the effects of all-trans-retinoic acid (trans-RA) and receptor class-selective retinoids on the growth and apoptosis of human lung cancer cell lines. Trans-RA significantly inhibited the growth of Calu-6 and H460 cells, accompanied by induction of RA receptor (RAR) beta expression. In contrast, it had little effect on the growth of H292, SK-MES-1 and H661 lung cancer cell lines, in which RAR beta expression was not induced. Stable expression of RAR beta in RAR beta-negative, trans-RA-resistant SK-MES-1 and H661 lung cancer cells led to recovery of trans-RA-induced growth inhibition, which occurred, however, only at low serum concentration. Using fluorescent microscopy and the terminal deoxyribonucleotidyl transferase (TdT) assay, we demonstrated that induction of apoptosis by trans-RA contributed to its growth-inhibitory effect in trans-RA-sensitive lung cancer cell lines. Analysis of RAR-selective and retinoid X receptor (RXR)-selective retionoids showed that activation of both RARs and RXRs could induce growth inhibition in trans-RA-sensitive lung cancer cells. Also, an additive synergistic effect on growth inhibition and RAR beta induction was observed when cells were treated with combinations of RAR-selective and RXR-selective retinoids. Together, our results show that expression of RAR beta plays a role in mediating retinoid response in lung cancer cells and that activation of RARs or RXRs contributes to induction of RAR beta, growth inhibition and apoptosis by retinoids.

Electrospray mass spectrum of a per(onio)-substituted benzene: retention of coulombic charge upon collisionally activated decomposition

The hexakis (4-diemthylaminopyridyl) benzene hexacation of 1 is investigated as an extreme example of the ability of electrospray ionization to allow transfer of small multivalent ions to the gas phase. The hexacationized benzene ring ions are stabilized by forming gas phase complexes with two to five trifluoromethanesulfonate counterions. MS/MS analysis reveals that their fragmentation takes place by loss of neutrals such as trifluoromethanesulfonic acid and 4-dimethylaminopyridine; no rupture of the benzene or pyridine rings was observed in spite of accumulation of positive charge in a restricted geometry.

Characterization of human N8 protein

We have shown before that the N8 mRNA is expressed at higher levels in lung tumor and lung tumor-derived cell lines than normal lung cells. In this paper, we have characterized the N8 protein, and studied its properties. The N8 gene encodes a major 24 kDa protein and its expression correlates well with the N8 mRNA expression pattern observed in different cell lines. N8 protein is capable of forming a homodimer or multimeter in vitro. It is a phosphorylated cytoplasmic protein and phosphorylation occurs mainly at serine residues. N8 protein is expressed at higher levels in epithelial cells than in mesenchymal cells. N8 protein expression is induced in a fibroblast cell line expressing adenoviral Ela protein, which acquired epithelial-like characteristics. Furthermore, ectopic expression of N8 protein in NIH3T3 cells converts them into a spheroid form. These spheroids also have some of the characteristic features of epithelial cells. Taken together, these results suggest that the N8 protein may be associated with the development or maintenance of epithelial cell phenotype.

Inhibition of trans-retinoic acid-resistant human breast cancer cell growth by retinoid X receptor-selective retinoids

All-trans-retinoic acid (trans-RA) and other retinoids exert anticancer effects through two types of retinoid receptors, the RA receptors (RARs) and retinoid X receptors (RXRs). Previous studies demonstrated that the growth-inhibitory effects of trans-RA and related retinoids are impaired in certain estrogen-independent breast cancer cell lines due to their lower levels of RAR alpha and RARbeta. In this study, we evaluated several synthetic retinoids for their ability to induce growth inhibition and apoptosis in both trans-RA-sensitive and trans-RA-resistant breast cancer cell lines. Our results demonstrate that RXR-selective retinoids, particularly in combination with RAR-selective retinoids, could significantly induce RARbeta and inhibit the growth and induce the apoptosis of trans-RA-resistant, RAR alpha-deficient MDA-MB-231 cells but had low activity against trans-RA-sensitive ZR-75-1 cells that express high levels of RAR alpha. Using gel retardation and transient transfection assays, we found that the effects of RXR-selective retinoids on MDA-MB-231 cells were most likely mediated by RXR-nur77 heterodimers that bound to the RA response element in the RARbeta promoter and activated the RARbeta promoter in response to RXR-selective retinoids. In contrast, growth inhibition by RAR-selective retinoids in trans-RA-sensitive, RAR alpha-expressing cells most probably occurred through RXR-RAR alpha heterodimers that also bound to and activated the RARbeta promoter. In MDA-MB-231 clones stably expressing RAR alpha, both RARbeta induction and growth inhibition by RXR-selective retinoids were suppressed, while the effects of RAR-selective retinoids were enhanced. Together, our results demonstrate that activation of RXR can inhibit the growth of trans-RA-resistant MDA-MB-231 breast cancer cells and suggest that low cellular RAR alpha may regulate the signaling switch from RAR-mediated to RXR-mediated growth inhibition in breast cancer cells.

Randomized, controlled trial of high-dose intravenous pyridoxine in the treatment of recurrent seizures in children

To determine the efficacy of pyridoxine in treating seizures, 90 infants and children with recurrent convulsions primarily due to acute infectious diseases were enrolled in the present study. Forty patients were treated with high-dose pyridoxine (30 or 50 mg/kg/day) by intravenous infusion, and 50 subjects served as controls. Antiepileptic drugs and other therapies were similar in the two groups except for pyridoxine. Clinical efficacy criteria were based on the frequency of convulsions per day and on the duration of individual seizures after therapy was initiated. The results indicated that total response rates in the pyridoxine group and control group were 92.5% and 64%, respectively (chi-square = 14.68, P < .001). After initiation of therapy, seizures resolved after 2.4 +/- 1.4 days in the pyridoxine group and after 3.7 +/- 2.0 days in the control group (t = 3.67, P < .001). No adverse effects of pyridoxine were apparent during the observation period. We conclude that pyridoxine is an effective, safe, well-tolerated, and relatively inexpensive adjunct to routine antiepileptic drugs for treatment of recurrent seizures in children.

Effects of receptor class- and subtype-selective retinoids and an apoptosis-inducing retinoid on the adherent growth of the NIH:OVCAR-3 ovarian cancer cell line in culture

Comparison of the adherent growth inhibition of NIH:OVCAR-3 ovarian cancer cells by retinoid receptor class-selective and subtype-selective compounds with their receptor binding affinities and transcriptional activation activities indicated no correlation for RAR alpha and RAR gamma although both receptors are present. Retinoids that activated RXR alpha inhibited cell growth in the range as all-trans-retinoic acid and 9-cis-retinoic acid. The most potent inhibitor was 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid (AHPN), which has been found to inhibit breast and lung cancer and leukemia cell growth and induce cancer cell apoptosis through a pathway independent of the retinoid receptors.

Propranolol and bepridil attenuating levothyroxine-induced rat cardiac hypertrophy and mitochondrial Ca2+ Mg(2+)-ATPase activity elevation

AIM

To study the effects of propranolol and bepridil on levothyroxine-induced rat cardiac hypertrophy and mitochondrial Ca2+ Mg(2+)-ATPase activity elevation.

METHODS

Rat heart hypertrophy was induced by i.p., levothyroxine 1 mg.kg-1.d-1 x 10 d. Then rats were treated by ig propranolol (Pro) or bepridil (Bep) 10 mg.kg-1 daily. Ca2+ Mg(2+)-ATPase activity and enzyme kinetic parameters were assayed.

RESULTS

The activity and Vmax of mitochondrial Ca2+ Mg(2+)-ATPase isolated from hypertrophic left ventricle were 25 +/- 4 and 35.1 +/- 0.8 mumol Pi.h-1/mg protein, respectively, those of normal were 6.7 +/- 1.8 and 10 +/- 4 mumol Pi.h-1/mg protein, respectively. Apparent K(m) of the hypertrophic group Ca2+ Mg(2+)-ATPase was 0.4 +/- 0.12 mmol.L-1 ATP, and that of normal was 0.59 +/- 0.22 mmol.L-1 ATP. The total protein quantity of hypertrophic left ventricle was 80 +/- 30 mg, and that of normal was 47 +/- 9 mg. After treated with Pro or Bep (both 10 mg.kg-1 ig), the cardiac hypertrophy was attenuated, the enzyme activity and Vmax as well as total protein quantity of hypertrophic left ventricle were reduced to normal level, but apparent K(m) was not affected.

CONCLUSION

Both Pro and Bep prevented the myocardium and its mitochondria from ischemia and overload calcium injury.

Increased expression of the ETS-related transcription factor FLI-1/ERGB correlates with and can induce the megakaryocytic phenotype

The human leukemia cell line K562 can be induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) to differentiate along the megakaryocytic pathway, generating morphological changes and increased expression of lineage-specific surface markers. We report that TPA-treated K562 cells also express higher levels of FLI-1/ERGB, a member of the ETS family of transcription factors. Furthermore, introduction of a retroviral construct expressing human FLI-1/ERGB into K562 cells induces changes similar to those seen following TPA treatment, including increased adherence to the surface of the culture vessel and altered size and morphology. Infected cells exhibit higher levels of the megakaryocyte marker CD41a and, to a lesser extent, CD49b. These markers, as well as virally encoded FLI-1/ERGB-specific RNA and protein, are expressed at the highest levels in the attached cell population, while the growth rate of adherent cells is reduced, and the fraction of cells in G0-G1 is increased. FLI-1/ERGB virus-infected cells also exhibit increased expression of hemoglobin, a marker of erythroid differentiation. Our results suggest FLI-1/ERGB plays a role in controlling differentiation and gene expression along the megakaryocyte/platelet pathway, and further implicate ETS-related genes in the control of multiple developmentally regulated hematopoietic genes.

Rubber stoppers as sources of contaminants in electrospray analysis of peptides and proteins

Using MS/MS, we have identified ions at m/z 399, 421, 609.4, and 819.9 as those of tris (2-butoxyethyl) phosphate, originating in the gray rubber stoppers commonly used as closures in commercial sources of peptides and proteins. The compound is readily extracted by contact with organic solvents such as alcohol or acetic acid and even by water alone. Zinc salts of proteins are also observed, presumably from zinc oxide fillers present in the stoppers.

Biochemical characteristics and differentiating activity of 4-oxo analogs of retinoic acid

3-Methyl-4-oxoretinoic acid and 3-cinnamyl-4-oxoretinoic acid bind to a cellular retinoic acid-binding protein (CRABP-II) and to a retinoic acid-receptor protein (RARa). These analogs of 4-oxoretinoic acid, as well as the parent compound, have less binding affinity than retinoic acid. Cotransfection assays in CV-1 cells with plasmids containing cDNAs for RAR alpha, RAR beta and RAR gamma (homodimers) and RAR alpha-RXR alpha and RAR beta-RXR alpha (heterodimers), indicate that 3-cinnamyl-4-oxoretinoic acid induces relatively less transcriptional activity than 4-oxoretinoic acid and its 3-methyl analog, both of which are less effective than retinoic acid. In differentiating mouse F9 embryocarcarcinoma cells, the order of effectiveness is retinoic acid > 4-oxoretinoic acid = 3-methyl-4-oxoretinoic acid > 3-cinnamyl-4-oxoretinoic acid. This order of potency is similar to that for inhibition of induction of ornithine decarboxylase (ODC) activity and for prevention of papillomas on the skin of mice. Binding to CRABP-II and activation of RARs appear to be important factors for expression of differentiating activity, inhibition of induction of ODC activity and prevention of papillomas on the skin of mice.

Changes in liver membrane potentials after partial hepatectomy in rats

Changes in potential differences (PD) across hepatocyte membranes after partial hepatectomy may play an important role in hepatic homeostatic mechanisms and regenerative activity. To date, few studies have attempted to describe the extent and duration of such changes. In the present study, we documented PD values immediately before and for a 24-hour period after a partial hepatectomy (PHx) of 70% in healthy adult rats. We also documented PD changes after 30% and 90% PHx and PD values in different lobes of the same liver before and after PHx. Our findings showed that the liver depolarizes promptly (within 5 minutes of PHx) and that changes in PD are sustained for approximately 18 hours before returning to baseline values. We also observed that the magnitude of hepatic depolarization correlates with the extent of PHx. Finally, we did not observe regional differences in PD recordings from various lobes before and after PHx. These findings enhance our understanding of the physiological changes that occur in regenerating livers after PHx in rats.

Retinoid receptors in human lung cancer and breast cancer

Retinoids, the natural and synthetic vitamin A derivatives, are known to inhibit the proliferation of lung cancer and breast cancer cells and the growth of carcinogen-induced bronchogenic squamous cell carcinoma and mammary tumors, and have been used as chemoprevention agents against both types of cancer. However, clinical trials of retinoids in patients with advanced lung cancer and breast cancer have not been successful. In studying how retinoid sensitivity is lost in cancer cells, we have found that lack of the retinoic acid receptor beta (RAR beta) gene expression and its abnormal regulation by retinoic acid (RA) are common features in human lung cancer and breast cancer cells. The absence and abnormal RA regulation of RAR beta correlates with the loss of anti-proliferation effect of RA in hormone-independent breast cancer cells, and is due to different abnormalities found in cancer cells. Furthermore, expression of RAR beta gene in hormone-independent breast cancer cells restores their RA sensitivity. These data demonstrate that RAR beta can mediate the growth inhibitory effect of RA and suggest that the lack of RAR beta may contribute to retinoid resistance in certain cancer cells.