[Synthesis of benzodihydropyran derivatives and evaluation of their preliminary biological activities on bone and vascular tissues]

AIM

To screen optimal drugs against postmenopausal osteoporosis with cardiovascular protective activities.

METHODS

A series of benzodihydropyran derivatives were designed and synthesized in view of comprehensive observations of raloxifene and ipriflavone. The antiosteoporosis activities of compounds a-e (10(-7) mol.L-1) on the proliferation of human osteoblast cell HOS TE85 were studied. The cardiovascular protective activities were evaluated by observing their effects on proliferation of human vascular endothelium cell ECV-304 and their protective effects on ECV-304 damaged by H2O2.

RESULTS

Their structures were determined by spectrums. Compounds a, b and c (10(-7) mol.L-1) were shown to significantly help proliferation of HOS TE85. In addition, b, d and e (10(-8) mol.L-1) helped proliferation of ECV-304 significantly. Compounds b and c (10(-6) mol.L-1) showed strong protective activity on ECV-304 damaged by H2O2. Compounds b and c shifted the KCl dose-response curves to the right and decreased the maximal response.

CONCLUSION

Compounds b and c showed some bone and vascular protective activities which benefit postmenopausal and cardiovascular diseases.

Combined prostaglandin and nitric oxide inhibition produces anatomic remodeling and closure of the ductus arteriosus in the premature newborn baboon

After birth, the full-term ductus arteriosus actively constricts and undergoes extensive histologic changes that prevent subsequent reopening. These changes are thought to occur only if a region of intense hypoxia develops within the ductus wall after the initial active constriction. In preterm infants, indomethacin-induced constriction of the ductus is often transient and is followed by reopening. Prostaglandins and nitric oxide both play a role in inhibiting ductus closure in vitro. We hypothesized that combined inhibition of both prostaglandin and nitric oxide production (with indomethacin and N-nitro-L-arginine (L-NA), respectively) may be required to produce the degree of functional closure that is needed to cause intense hypoxia. We used preterm (0.67 gestation) newborn baboons that were mechanically ventilated for 6 d: 6 received indomethacin alone, 7 received indomethacin plus L-NA, and 16 received no treatment (control). Just before necropsy, only 25% of control ductus and 33% of indomethacin-treated ductus were closed on Doppler examination; in contrast, 100% of the indomethacin-plus-L-NA-treated ductus were closed. Control and indomethacin-treated baboons developed negligible-to-mild ductus hypoxia (EF5 technique). Similarly, there was minimal evidence of ductus remodeling. In contrast, indomethacin-plus-L-NA-treated baboons developed intense hypoxia in regions where the ductus was most constricted. The hypoxic muscle strongly expressed vascular endothelial growth factor, and proliferating luminal endothelial cells filled and occluded the lumen. In addition, cells in the most hypoxic regions were undergoing DNA fragmentation. In conclusion, preterm newborns are capable of remodeling their ductus, just like the full-term newborn, if they can reduce their luminal blood flow to a point that produces intense ductus wall hypoxia. Combined prostaglandin and nitric oxide inhibition may be necessary to produce permanent closure of the ductus and prevent reopening in preterm infants.

Accelerated hazards regression model and its adequacy for censored survival data

The accelerated hazards regression model is introduced to study the relationship between survival times and covariates through a scale change between hazard functions. The model is also compared with several other popular classes of regression models for censored survival data in statistical literature. Test statistics are proposed and studied to assess the model's adequacy. Actual data from a randomized clinical trial of biodegradable carmustine polymer for treatment of brain cancer are analyzed to demonstrate the potential application of the regression model and the proposed test statistics.

X-ray crystal structure of proto-oncogene product c-Rel bound to the CD28 response element of IL-2

BACKGROUND

The proto-oncogene product c-Rel is a Rel/NF-kappaB family transcription factor that plays a critical role in lymphoid cell development and mediates CD28-induced expression of interleukin 2 (IL-2). The CD28 response element (CD28RE) in the IL-2 enhancer is nonameric and similar to the kappaB DNA target sites recognized by p65 homodimers.

RESULTS

We have determined and refined the X-ray crystal structure of the c-Rel homodimer complexed to the CD28RE DNA site, 5'-AGAAATTCC-3', to 2.85 A resolution. The c-Rel homodimer binds CD28RE in a mode similar to that observed in the p65/IL-8 kappaB crystallographic complex. Binding studies reveal that the c-Rel homodimer recognizes the CD28RE with higher affinity as compared to other canonical kappaB sequences despite the nonconsensus A:T base pair at the 5' end of the CD28RE. Preferential recognition of the CD28RE by c-Rel results from the direct contacts between the protein and the DNA as well as intrasubunit interactions between the beta(f)-beta(g) loop in the dimerization domain and the DNA-contacting loop L1 of the N-terminal domain. Not only do these loops have different conformations in other Rel/DNA crystallographic complexes, but they also contain two of the five oncogenic point mutations found in v-Rel.

CONCLUSIONS

The current structure indicates that a non-DNA-contacting loop in the dimerization domain and the DNA-contacting loop L1 may play critical roles in defining affinity and specificity. Two amino acid changes in these segments may account for the differential DNA binding by v-Rel as compared to that of c-Rel.

Factors that increase the contractile tone of the ductus arteriosus also regulate its anatomic remodeling

Permanent closure of the full-term newborn ductus arteriosus (DA) occurs only if profound hypoxia develops within the vessel wall during luminal obliteration. We used fetal and newborn baboons and lambs to determine why the immature DA fails to remodel after birth. When preterm newborns were kept in a normoxic range (Pa(O(2)): 50-90 mmHg), 86% still had a small patent DA on the sixth day after birth; in addition, the preterm DA wall was only mildly hypoxic and had only minimal remodeling. The postnatal increase in Pa(O(2)) normally induces isometric contractile responses in rings of DA; however, the excessive inhibitory effects of endogenous prostaglandins and nitric oxide, coupled with a weaker intrinsic DA tone, make the preterm DA appear to have a smaller increment in tension in response to oxygen than the DA near term. We found that oxygen concentrations, beyond the normoxic range, produce an additional increase in tension in the preterm DA that is similar to the contractile response normally seen at term. We predicted that preterm newborns, kept at a higher Pa(O(2)), would have increased DA tone and would be more likely to obliterate their lumen. We found that preterm newborns, maintained at a Pa(O(2)) >200 mmHg, had only a 14% incidence of patent DA. Even though DA constriction was due to elevated Pa(O(2)), obliteration of the lumen produced profound hypoxia of the DA wall and the same features of remodeling that were observed at term. DA wall hypoxia appears to be both necessary and sufficient to produce anatomic remodeling in preterm newborns.

Identification of differentially expressed genes by serial analysis of gene expression in human prostate cancer

Prostate cancer is the leading cause of cancer death in American males. To better understand the genetic bases of this disease, we have generated a comprehensive molecular profile of human prostate. The gene expression pattern in normal and prostate cancer tissues was analyzed by serial analysis of gene expression (SAGE). A total of 133,217 transcripts were analyzed, and 35,185 distinct SAGE tags were identified representing 19,287 genes. Comparison of the transcripts in normal and tumor tissue revealed 156 differentially expressed genes (P < 0.05), of which 88 genes were up-regulated and 68 genes were down-regulated in the tumor tissue. Based on SAGE data, we estimate that the transcriptome for human prostate is approximately 37,000. Several differentially expressed genes identified by SAGE were selected for confirmation using immunohistochemistry. Some genes (e.g., E2F4) were overexpressed in tumor epithelial cells and some (e.g., Daxx) were increased in tumor stroma. Further characterization of the role of E2F4 and Daxx as well as other differentially expressed genes may provide useful insights into the mechanism of prostate cancer development.

In utero remodeling of the fetal lamb ductus arteriosus: the role of antenatal indomethacin and avascular zone thickness on vasa vasorum proliferation, neointima formation, and cell death

BACKGROUND

The ductus arteriosus (DA) of newborn infants exposed in utero to indomethacin is resistant to postnatal indomethacin; we hypothesized that this is due to ductus constriction in utero, with subsequent remodeling of the vessel.

METHODS AND RESULTS

Infusion of fetal lambs with indomethacin for 48 hours constricted the DA and increased the thickness of the avascular zone of the DA, which in turn induced the expression of vascular endothelial growth factor, endothelial nitric oxide synthase (due to ingrowth of vasa vasorum), neointima formation, and loss of smooth muscle cells; moderate degrees of DA constriction in utero increased NO production, which inhibited DA contractility. Marked degrees of DA constriction decreased tissue distensibility and contractile capacity.

CONCLUSIONS

DA patency is no longer controlled primarily by prostaglandins once it has been exposed to indomethacin in utero.

Identification of 10 novel snoRNA gene clusters from Arabidopsis thaliana

Ten novel small nucleolar RNA (snoRNA) gene clusters, consisting of two or three snoRNA genes, respectively, were identified from Arabidopsis thaliana. Twelve of the 25 snoRNA genes in these clusters are homologous to those of yeast and mammals according to the conserved antisense sequences that guide 2'-O-ribose methylation of rRNA. The remaining 13 snoRNA genes, including two 5.8S rRNA methylation guides, are new genes identified from A.thaliana. Interestingly, seven methylated nucleotides, predicted by novel snoRNAs Z41a-Z46, are methylated neither in yeast nor in vertebrates. Using primer extension at low dNTP concentration the six methylation sites were determined as expected. These snoRNAs were recognized as specific guides for 2'-O:-ribose methylation of plant rRNAs. Z42, however, did not guide the expected methylation of 25S rRNA in our assay. Thus, its function remains to be elucidated. The intergenic spacers of the gene clusters are rich in uridine (up to 40%) and most of them range in size from 35 to 100 nt. Lack of a conserved promoter element in each spacer and the determination of polycistronic transcription from a cluster by RT-PCR assay suggest that the snoRNAs encoded in the clusters are transcribed as a polycistron under an upstream promoter, and individual snoRNAs are released after processing of the precursor. Numerous snoRNA gene clusters identified from A.thaliana and other organisms suggest that the snoRNA gene cluster is an ancient gene organization existing abundantly in plants.

[Clinical study on effect of ginsenoside in inducing rectal cancer cell apoptosis]

OBJECTIVE

To explore the effect of ginsenoside in inducing rectal cancer cell apoptosis.

METHODS

Fifty patients of rectal cancer diagnosed by pathological examination were randomly divided into two groups, 35 in the treated group and 15 in the control group. The treated group received retention enema with 84.5% ginsenoside for 4-6 hrs every day, 6-8 days consecutively before surgical operation. The control group also received retention enema in the same way but with normal saline instead of ginsenoside. Fresh sample was taken during the operation and examined by electron microscopy.

RESULTS

Symptoms, such as frequent defecation, hematochezia and tenesmus, were palliated in most patients (25/35) and abdominal pain relieved in all the 7 cases of incomplete intestinal obstruction in the treated group. Electron microscopic examination showed that cell apoptosis was observed in cancer sample of 23 cases among the 35 cases of the treated group, amounting to 65.7%. While in the control group, above-mentioned changes were not observed at all.

CONCLUSION

Ginsenoside has the effect of inducing apoptosis in rectal cancer patients.

Overexpression and activation of the RON receptor tyrosine kinase in a panel of human colorectal carcinoma cell lines

RON is a receptor tyrosine kinase belonging to the MET proto-oncogene family. The purposes of this study are to determine the expression and activation of RON in a panel of human colon carcinoma cell lines. Western blotting showed that RON is barely detectable in normal and SV-40-transformed colon epithelial cells, but highly expressed and constitutively activated in several colon carcinoma cell lines including Colo201, HT-29, HCT116, and SW837. Moreover, a novel RON variant with a molecular mass of 160 kDa (RONDelta160) was identified from HT-29 cells. The cDNA encoding RONDelta160 has an in-frame deletion of 109 amino acids in the extracellular domain of the RON beta chain, which is caused by splicing out of two exons in the RON mRNA. No mutations were found in the kinase domain of the RON gene in five carcinoma cell lines screened. By expressing RON in colon epithelial cells, we found that RON activation increases cell motile-invasive activities and protects cells against apoptotic death. These data suggest that RON expression and activation are deregulated in colon carcinoma cell lines. By abnormal activation of RON, this receptor and its variant may regulate motile-invasive phenotypes of certain colon carcinoma cells in vivo.

Nonparametric and semiparametric trend analysis for stratified recurrence times

Recurrent event data are frequently encountered in longitudinal follow-up studies when the occurrences of multiple events are considered as the major outcomes. Suppose that the recurrent events are of the same type and the variable of interest is the recurrence time between successive events. In many applications, the distributional pattern of recurrence times can be used as an index for the progression of a disease. Such a distributional pattern is important for understanding the natural history of a disease or for confirming long-term treatment effect. In this article, we discuss and define the comparability of recurrence times. Nonparametric and semiparametric methods are developed for testing trend of recurrence time distributions and estimating trend parameters in regression models. The construction of the methods is based on comparable recurrence times from stratified data. A real data example is presented to illustrate the use of methodology.

Estimating a treatment effect with the accelerated hazards models

In randomized clinical trials, when the outcome of interest is time to event, the proportional hazards model or the accelerated failure time model is often used to identify a treatment effect. In this article, we discuss a simple alternative called the accelerated hazards model in which the treatment effect is characterized as the hazard progression time ratio, when the treatment is believed to accelerate or decelerate the underlying hazard progression through time. Survival data from an actual randomized placebo-controlled trial, which evaluates the effectiveness of biodegradable polymers with carmustine to treat malignant gliomas, is used for illustration.

Tissue hypoxia inhibits prostaglandin and nitric oxide production and prevents ductus arteriosus reopening

Regulation of ductus arteriosus (DA) tension depends on a balance between oxygen-induced constriction and PG and nitric oxide (NO)-mediated relaxation. After birth, increasing Pa(O(2)) produces DA constriction. However, as the full-term ductus constricts, it develops severe tissue hypoxia in its inner vessel wall (oxygen concentration <0.2%). We used isolated rings of fetal lamb DA to determine why the constricted ductus does not relax and reopen as it becomes hypoxic. We used a modification of the 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide (EF5) technique (Clyman RI, Chan CY, Mauray F, Chen YQ, Cox W, Seidner SR, Lord EM, Weiss H, Wale N, Evan SM, and Koch CJ. Pediatr Res 45: 19-29, 1999) to determine mean tissue oxygen concentration. A decrease in the ductus' mean tissue oxygen concentration from 1.4 to 0.1% lowers the isometric tone of the ductus by 15 +/- 10% of its maximal active tension (the maximal tension that can be produced by the ductus). Although decreases in oxygen concentration diminish ductus tension, most of the vasoconstrictor tone in the ductus is independent of ambient oxygen concentration. This oxygen-independent tone is equivalent to 64 +/- 10% of the maximal active tension. At mean tissue oxygen concentrations >0.2%, endogenous PGs and NO inhibit more than 40% of the active tension developed by the ductus. However, when tissue oxygen concentrations drop below 0.2%, the constitutive relaxation of the ductus by endogenous PGs and NO is lost. In the absence of PG and NO production, tension increases to a level normally observed only after treatment of the ductus with indomethacin and nitro-L-arginine methyl ester (inhibitors of PG and NO production). Therefore, under conditions of severe hypoxia (tissue oxygen concentration <0.2% oxygen), the loss of PG- and NO-mediated relaxation more than compensates for the loss of oxygen-induced tension. We hypothesize that this increased ductus tone enables the vessel to remain closed as it undergoes tissue remodeling.

[Effects of culture conditions on callus growth and taxol formation of Taxus yunnanensis Cheng et L.K.Fu]

OBJECTIVE

To seek culture conditions suitable for the callus growth and taxol formation of Taxus yunnanensis.

METHOD

Determining the growth index and taxol content in the callus cultured under different illumination conditions or on different media.

RESULTS AND CONCLUSION

Darkness, the combination of 0.1 mg.L-1BAP and 2,4-D 1.0 mg.L-1, and B5, DCR or 6,7-V basal medium were favorable for the callus growth and taxol formation of Taxus yunnanensis; high NO3- concentration in the medium promoted callus growth, and high NH4+ concentration greatly inhibited callus growth, but dramatically increased taxol content.

NF-kappaB p65 (RelA) homodimer uses distinct mechanisms to recognize DNA targets

BACKGROUND

The NF-kappaB family of dimeric transcription factors regulates the expression of several genes by binding to a variety of related DNA sequences. One of these dimers, p65(RelA), regulates a subclass of these targets. We have shown previously that p65 binds to the 5'-GGAA T TTTC-3' sequence asymmetrically. In that complex one subunit base specifically interacts with the preferred 5' half site and the other subunit binds non-specifically to the 3' half site.

RESULTS

Here we describe the crystal structures of two new p65-DNA complexes. One complex contains a pseudosymmetric 5'-GGAA T TTCC-3' DNA sequence taken from the enhancer of the gene encoding interleukin 8 (IL-8) and the other contains the asymmetric 5'-GGAA T TCCC-3' target DNA taken from the enhancer of the gene encoding type VII collagen. As expected, the global positioning of the dimer on both DNA targets is roughly symmetric, however, the hydrogen-bonding patterns at the protein-DNA interfaces differ significantly. One of the p65 monomers in complex with the asymmetric DNA binds to an extra base pair located immediately upstream of the 5'-GGAA-3' half site. We also show that p65 binds to these targets with almost equal affinity and that different residues have variable roles in binding different kappaB targets.

CONCLUSIONS

Taken together, these structures reveal that p65 exhibits the unique capability to specifically bind DNA targets of variable lengths from four to ten base pairs. Also, the small protein segment Arg41-Ser42-Ala43 is at least partially responsible for flexibility in DNA-binding modes.

Regulation of the RON receptor tyrosine kinase expression in macrophages: blocking the RON gene transcription by endotoxin-induced nitric oxide

Previous studies have shown that activation of the RON receptor tyrosine kinase inhibits inducible NO production in murine peritoneal macrophages. The purpose of this study is to determine whether inflammatory mediators such as LPS, IFN-gamma, and TNF-alpha regulate RON expression. Western blot analysis showed that RON expression is reduced in peritoneal macrophages collected from mice injected with a low dose of LPS. The inhibition was seen as early as 8 h after LPS challenge. Experiments in vitro also demonstrated that the levels of the RON mRNA and protein are diminished in cultured peritoneal macrophages following LPS stimulation. TNF-alpha plus IFN-gamma abrogated macrophage RON expression, although individual cytokines had no significant effect. Because LPS and TNF-alpha plus IFN-gamma induce NO production, we reasoned that NO might be involved in the RON inhibition. Two NO donors, S-nitroglutathione (GSNO) and (+/-)-S-nitroso-N-acetylpenicillamine (SNAP), directly inhibited macrophage RON expression when added to the cell cultures. Blocking NO production by NO inhibitors like TGF-beta prevented the LPS-mediated inhibitory effect. In Raw264.7 cells transiently transfected with a report vector, GSNO or SNAP inhibited the luciferase activities driven by the RON gene promoter. Moreover, GSNO or SNAP inhibited the macrophage-stimulating protein-induced RON phosphorylation and macrophage migration. We concluded from these data that RON expression in macrophages is regulated during inflammation. LPS and TNF-alpha plus IFN-gamma are capable of down-regulating RON expression through induction of NO production. The inhibitory effect of NO is mediated by suppression of the RON gene promoter activities.

Requirement of both tyrosine residues 1330 and 1337 in the C-terminal tail of the RON receptor tyrosine kinase for epithelial cell scattering and migration

RON is a receptor tyrosine kinase that mediates cell scattering, migration, and tubular formation. This study focused on the function of two tyrosines, Y1330 and Y1337, in the C-terminus of RON in regulating epithelial cell scattering and migration. Substitution of both tyrosine residues with phenylalanine causes complete loss of cell scattering and migration in kidney 293 cells. In contrast, single mutation of either tyrosine residue has no effect. We found that mutation at Y1330 or Y1337 alone does not significantly affect the association of RON with PI-3 kinase, whereas a double mutation abolishes the recruitment of substrates. RON-mediated cell migration was inhibited by PI-3 kinase inhibitor wortmannin. This effect was also achieved by a dominant inhibitory p85 of PI-3 kinase. We conclude that Y1330 and Y1337 are required for RON-mediated cell motility. By associating with PI-3 kinase, the Y1330-Y1337 docking site plays a critical role in transducing motile signals of RON.

H-ras, but not N-ras, induces an invasive phenotype in human breast epithelial cells: a role for MMP-2 in the H-ras-induced invasive phenotype

Elevated p21ras expression is associated with tumor aggressiveness in breast cancer including the extent of invasion into fat tissues, infiltration into lymphatic vessels and tumor recurrence. In the present study, we have examined the roles of H-ras and N-ras, members of the human ras gene family, in the pathogenesis of breast cancer. We show that H-ras, but not N-ras, induces an invasive phenotype in human breast epithelial cells (MCF10A) as determined by the Matrigel invasion assay, whereas both H-ras and N-ras induce anchorage-independent growth, as shown by soft agar assay. We examined the effects of H-ras and N-ras activation on the expression of MMP-2 and MMP-9, which can degrade type IV collagen, the major structural collagen of the basement membrane. We show that MMP-2 is efficiently induced by H-ras, whereas MMP-9 induction is more prominent in N-ras-activated MCF10A cells. We also show that H-ras-mediated invasiveness is significantly inhibited when the expression of MMP-2 is down-regulated, using an oligodeoxyribonucleotide complementary to the MMP-2 mRNA, or when MMP-2 activity is blocked by its inhibitor TIMP-2 (tissue inhibitors of matrix metalloproteinase-2). Our results show that the H-ras-induced invasive phenotype is associated more closely with the expression of MMP-2 in human breast epithelial cells, rather than the induction of MMP-9 expression, as shown previously for rat embryonic fibroblasts.

[Determination of chiral purity of synthetic amino acids by high performance liquid chromatography]

A series of synthetic beta-heterocyclic and beta-naphthyl alanine and aromatic substituted phenylalanine were separated by reversed-phase HPLC as diastereomeric derivatives obtained after derivatization with (1-fluoro-2,4-dinitrophenyl)-5-L-valinamide (FDNP-Val-NH2). The separation was performed with gradient elution. The mobile phase A was acetonitrile containing 0.1% trifluoroacetic acid and mobile phase B was 0.1% trifluoroacetic acid. According to the hydrophobicity of the side chain of the amino acids, 6 different linear gradient programs were selected and all gradients completed in 20 minutes. Good resolution was obtained for neutral amino acids. All L-L diastereomer of neutral amino acids (the first letter refers to the configuration of amino acid) were eluted faster than the D-L diastereomer with retention times less than 16 minutes. In the same gradient eluting system, the hydrophobic parameter (pi value) and the position of the substituent in benzene ring of phenylalanine also influence the retention time of diastereomers. Usually the retention time of the phenylalanine with a large pi value was longer than that with a small one. Among the three phenylalanines containing the same substituent, compounds with the substituent in 2-postion gave the shortest retention time. In the case of basic amino acids, the D-L diastereomers eluted prior to the L-L diastereomers and showed rather poor resolution. The chiral purity (ee) of the optical active amino acids (synthetic DL-amino acids after resolution by different enzymes) were calculated with the equation as follows: ee = [[A(L- or D-) - A(D- or L-)]/[A(L-) + A(D-)]] x 100% (L- or D-), A: peak area; L-, D-: amino acid diastereomer.

Synergistic effect of adrenal steroids and angiotensin II on plasminogen activator inhibitor-1 production

Recent data suggest an interaction between the renin-angiotensin-aldosterone system and fibrinolysis. Although previous work has focused on the effect of angiotensin II (Ang II) on plasminogen activator inhibitor (PAI-1) expression, the present study tests the hypothesis that aldosterone contributes to the regulation of PAI-1 expression. To test this hypothesis in vitro, luciferase reporter constructs containing the human PAI-1 promoter were transfected into rat aortic smooth muscle cells. Exposure of the cells to 100 nmol/L Ang II resulted in a 3-fold increase in luciferase activity. Neither 1 micromol/L dexamethasone nor 1 micromol/L aldosterone alone increased PAI-1 expression. However, both dexamethasone and aldosterone enhanced the effect of Ang II in a dose-dependent manner. This effect was abolished by mutation in the region of a putative glucocorticoid-responsive element. A similar interactive effect of Ang II and aldosterone was observed in cultured human umbilical vein endothelial cells. The time course of the effect of aldosterone on Ang II-induced PAI-1 expression was consistent with a classical mineralocorticoid receptor mechanism, and the effect of aldosterone on PAI-1 synthesis was attenuated by spironolactone. To determine whether aldosterone affected PAI-1 expression in vivo, we measured local venous PAI-1 antigen concentrations in six patients with primary hyperaldosteronism undergoing selective adrenal vein sampling. PAI-1 antigen, but not tissue plasminogen activator antigen, concentrations were significantly higher in adrenal venous blood than in peripheral venous blood. Taken together, these data support the hypothesis that aldosterone modulates the effect of Ang II on PAI-1 expression in vitro and in vivo in humans.

The level of tyrosine kinase activity regulates the expression of p21/WAF1 in cancer cells

It is well documented that epidermal growth factor (EGF) inhibits proliferation of A431 and MDA-468 cells via activation of p21/WAF1. In the present study, we have shown that treatment of MDA-468 and A431 cells that express high levels of EGFR with 100 ng/ml of EGF leads to 14.9-fold increase in epidermal growth factor receptor (EGFR) autophosphorylation and high levels of p21/WAF1-induction (6. 7-fold), down regulation of cdk2 activity and growth arrest. When MDA-468 or A431 cells were simultaneously treated with 100 ng/ml EGF and RG13022, a relatively specific tyrosine kinase inhibitor, there was a significant reduction in p21/WAF1 levels. In contrast, when MDA-468, A432 cells that are treated with low levels of EGF (10 ng/ml) or other cells which express low to moderate levels of EGFRs such as MCF-7, MCF-10A, MDA-231 and SKBR-3 breast cells were exposed to 100 ng/ml of EGF there was a 3.8-fold increase in EGFR autophosphorylation, leading to 1.6-fold induction of p21/WAF1 and increased cell proliferation. These results suggest that the level of EGFR tyrosine kinase activity may regulate p21/WAF1 induction in cancer cells.

Expression of the alpha7beta1 laminin receptor suppresses melanoma growth and metastatic potential

The alpha7beta1 integrin is a laminin-binding receptor that was originally identified in melanoma. Here, we show that, in clonally derived mouse K1735 melanoma variant cell lines with high (M-2) and low (C-23) metastatic potential, elevated expression of alpha7 correlates with reduced cell motility, metastasis, and tumor growth. Both cell lines showed similar beta1 integrin-dependent adhesion to laminin-1 and the E8 laminin fragment. However, the highly metastatic M-2 cells rapidly migrated on laminin, whereas the nonmetastatic C-23 cells were minimally motile. Laminin-binding integrin profiles showed that the M-2 cells expressed moderate amounts of alpha1 and abundant alpha6 but low or undetectable levels of alpha2 and alpha7. By contrast, C-23 cells expressed low or undetectable levels of alpha1, alpha2, and alpha6 but had up-regulated levels of alpha7. Consistent with the protein data, Northern blot analysis showed that levels of alpha7 mRNA were highest in the poorly metastatic variant cells, whereas alpha6 message was not detected; in contrast, alpha6 mRNA was elevated in the highly metastatic cells, whereas alpha7 message was not detected. Forced expression of alpha7 in the M-2 cells suppressed cell motility, tumor growth, and metastasis. Collectively, these results indicate that, during melanoma progression, acquisition of a highly tumorigenic and metastatic melanoma phenotype is associated with loss of the alpha7beta1 laminin receptor.

[Regulation of cell cycle by retinoic acid in gastric cancer cells]

Retinoic acid can induce growth inhibition and apoptosis, and regulate cell cycle in many types of cancer cell lines. In this study, we investigated the role of all-trans retinoic acid (ATRA) and its mechanism of action in human gastric cancer cell lines. Our results demonstrated that ATRA effectively inhibited growth in three of four gastric cancer cell lines by induction of G0/G1 arrest, and did not induce apoptosis in four gastric cancer cell lines. In RA-sensitive cell lines, ATRA-induced G0/G1 arrest is associated with down regulaton of c-myc and hyperphosphorylated Rb expression, and up regulation of p21WAF1/CIP1 and p53 expression. There were no significant changes in cyclin D1 or CDK4 expression induced by ATRA. Futhermore, expression of these genes were not regulated by ATRA in ATRA-resistant gastric cancer cell line. These results indicate that growth inhibition, rather than apoptosis, is correlated with G0/G1 arrest of these cell lines, more important molecules related cell cycle, including c-myc, p21WAF1/CIP1, p53 and Rb, are involveed in regulation of cell cycle in gastric cancer cells.

Induction of apoptosis and G2/M cell cycle arrest by DCC

The Deleted in Colorectal Cancer gene (DCC) encodes a cell surface receptor that belongs to the Ig superfamily. Inactivation of the DCC gene has been implicated in human tumor progression. However, little is known about the biological function of the DCC protein. In the present study, we demonstrated that expression of DCC activated caspase-3 and programmed cell death, or induced G2/M cell cycle arrest in tumor cells. In some cell lines, apoptosis was evident within 24 h of DCC expression. Timing of the appearance of apoptotic cells coincided with that of the cleavage of poly (ADP-ribose) polymerase, a substrate of caspase-3. Expression of the apoptosis inhibitory gene Bcl-2 was not able to abrogate the DCC-induced apoptosis. In the G2/M cycle arrest cells, cdk1 activity was inhibited. Our results suggest that the DCC protein may transduce signals resulting in activation of caspases or inhibition of Cdk1. These data provide a possible mechanism by which DCC suppresses tumorigenesis.

Inhaled IL-5 increases concentrations of soluble intracellular adhesion molecule-1 in sputum from atopic asthmatic subjects

BACKGROUND

Both IL-5 and intracellular adhesion molecule-1 (ICAM-1) have been shown to play important roles in the production of allergic inflammation, including atopic asthma.

OBJECTIVE

The aim of this study was to investigate the effects of recombinant human IL-5 on changes of soluble (s) ICAM-1 concentrations in induced sputum from allergic asthmatic subjects.

METHODS

In a randomized, double-blind, placebo-controlled study design, 8 nonsmoking patients with allergic asthma and 6 nonallergic normal subjects were administered recombinant human IL-5 by nebulization, and the concentrations of sICAM-1 in induced sputum from each subject were determined before and at 2, 24, 48, and 72 hours after inhalation.

RESULTS

sICAM-1 levels in sputum within the control group did not appear to change from baseline at any time throughout the study. In allergic asthmatic subjects vehicle challenge was not able to cause any changes in sputum sICAM-1 concentrations. However, there were increases in sputum sICAM-1 concentrations after IL-5 inhalation, which increased with time to significantly greater levels than those at baseline, reaching a maximum at 48 hours and lasting no less than 72 hours. The concentrations of sICAM-1 in sputum after IL-5 challenge exceeded levels that could be accounted for by passive transudation from the circulation on the basis of the magnitude of increases in sputum albumin concentration.

CONCLUSION

Our results indicated that IL-5 inhalation was capable of inducing an elevation of sputum sICAM-1 concentration by stimulating its local release in allergic asthmatic, but not in nonallergic normal, subjects.