Biomedical subjects

Chris Albanese

Publications and source records attributed to Chris Albanese.

At least 19 recordsLinked to original sources

PubMed2006

Cell cycle regulatory proteins in the liver in murine Trypanosoma cruzi infection.

The liver is an important target of Trypanosoma cruzi infection. Infection of CD-1 mice with T. cruzi (Brazil strain) resulted in parasitism of the liver, primarily in sinusoidal and Kupffer cells. Immunoblot analysis revealed activation of extra cellular signal-regulated kinase (ERK) during the acute and subacute period of infection, but p38 mitogen activated kinase (MAPK) and JNK were not activated. The activity of important cell cycle regulatory genes was also examined in the liver following infection. There was increased expression of cyclin D1, cyclin E and cyclin A as well as proliferating cell nuclear antigen (PCNA) at 45, 60 and 215 days post infection. In addition, the levels of the cyclin-dependent kinase inhibitors p27(KIP1), p21(WAF1) and the tumor suppressor p53 were increased in the livers obtained from infected mice. Quantitative PCR revealed increased abundance of mRNA for cyclins A, D1 and E. Interestingly, cyclin A and E are ordinarily not found in the adult liver. Thus infection caused a reversion to a fetal/neonatal phenotype. These data provide a molecular basis for cell proliferation in the liver following T. cruzi infection.

Animals↗

PubMed2006

p27Kip1 repression of ErbB2-induced mammary tumor growth in transgenic mice involves Skp2 and Wnt/beta-catenin signaling.

Expression of the cyclin-dependent kinase (Cdk) inhibitor (p27(Kip1)) is frequently reduced in human tumors, often correlating with poor prognosis. p27(Kip1) functions as a haploinsufficient tumor suppressor; however, the mechanism by which one allele of p27(Kip1) regulates oncogenic signaling in vivo is not well understood. We therefore investigated the mechanisms by which p27(Kip1) inhibits mammary tumor onset. Using the common background strain of FVB, p27(Kip1) heterozygosity (p27(+/-)) accelerated ErbB2-induced mammary tumorigenesis. We conducted microarray analyses of mammary tumors developing in mice with genetic haploinsufficiency for p27(Kip1) expressing a mammary-targeted ErbB2 oncogene. Global gene expression profiling and Western blot analysis of ErbB2/p27(+/-) tumors showed that the loss of p27(Kip1) induced genes promoting lymphangiogenesis, cellular proliferation, and collaborative oncogenic signaling (Wnt/beta-catenin/Tcf, Cdc25a, Smad7, and Skp2). Skp2 expression was induced by ErbB2 and repressed by p27(Kip1). Degradation of p27(Kip1) involves an SCF-type E3 ubiquitin ligase, including Skp2. The Skp2 component of the SCF(SKP2) complex that degrades p27(Kip1) was increased in ErbB2 tumors correlating with earlier tumor onset. In both murine and human ErbB2-overexpressing breast cancers, p27(Kip1) levels correlated inversely with Skp2. p27(Kip1) haploinsufficiency activated Wnt/beta-catenin/hedgehog signaling. Reintroduction of p27(Kip1) inhibited beta-catenin induction of Tcf-responsive genes (Siamosis, c-Myc, and Smad7). p27(Kip1) is haploinsufficient for ErbB2 mammary tumor suppression in vivo and functions to repress collaborative oncogenic signals including Skp2 and Wnt/beta-catenin signaling.

Animals↗

PubMed2006

In vivo magnetic resonance volumetric and spectroscopic analysis of mouse prostate cancer models.

BACKGROUND: Mouse prostate cancer modeling presents unique obstacles to the study of spontaneous tumor initiation and progression due to the anatomical location of the tissue. RESULTS: High resolution (130 microm(x) x 130 microm(y) x 300 microm(z)), three-dimensional MRI allowed for the visualization, segmentation, and volumetric measurement of the prostate from normal and genetically engineered animals, in vivo. Additionally, MRS performed on the prostate epithelia of probasin-ErbB-2Delta x Pten(+/-) mice identified changes in the relative concentrations of the metabolites choline and citrate, which was not observed in TRAMP mice. METHODS: T1-weighted MRI was performed on normal, TRAMP, probasin-ErbB-2/Her2/Neu (probasin-ErbB-2Delta), and probasin-ErbB-2Delta in the context of decreased Pten activity (probasin-ErbB-2Delta x Pten(+/-)) mice. Volume-localized single-voxel proton magnetic resonance spectroscopy (SVS (1)H MRS) was also performed. CONCLUSIONS: The data presented supports the use of combined MRI and MRS for the measurement of biochemical and morphometric alterations in mouse models of prostate cancer.

Animals↗

PubMed2006

Cyclin and caveolin expression in an acute model of murine Chagasic myocarditis.

Chagas' disease caused by the parasite, Trypanosoma cruzi, is accompanied by an acute myocarditis which can be fatal. Mice (A/J strain) infected with T. cruzi (Tulahuen strain) develop an acute myocarditis associated with high parasitemia and uniform mortality. Examination of the myocardium demonstrated myonecrosis, vasculitis and parasite pseudocysts. Immunoblot analysis and quantitative real time PCR of heart lysates demonstrated an increased expression of cell cycle regulatory proteins such as cyclins B1, D1, A1 and E1 and an increased expression of cdk2 when compared with uninfected controls. Extracellular signal-regulated kinase (ERK) was activated. Proliferating cell nuclear antigen (PCNA), endothelin-1, endothelin receptor type A (ET(A)) and endothelin receptor type B (ET(B)) expression were increased. Caveolin-1 is important in the regulation of ERK and cyclin D1. The expression of caveolin-1 as well as caveolin-2 and caveolin-3 was reduced. These data suggest that acute fatal T. cruzi myocarditis is accompanied by changes in cell cycle proteins such as the cyclins and caveolin and that the upregulation of the endothelin pathway may be important in the myocardial abnormalities and mortality observed in this mouse model.

Acute Disease↗

PubMed2006

Contrast-enhanced in vivo imaging of breast and prostate cancer cells by MRI.

The development of effective cancer therapies has been hampered, in part, by the inability to noninvasively follow tumor progression from the initial cancerous lesion through to metastasis. We have previously shown that superparamagnetic iron oxide particles can be used as magnetic resonance imaging contrast agents to label embryonic, mesenchymal and hematopoietic stem cells in vivo. Improving the capacity to non-invasively image cancer progression is an appealing method that could be useful for assessing the efficacy of anticancer therapies. We have established that human prostate (LNCaP, DU145, PC3), rodent prostate (TRAMPC1, YPEN-1), human breast (MDA-MB-231) and mouse mammary (Myc/VEGF) cancer cell lines were readily labeled by fluorescent superparamagnetic sub-micron particles of iron oxide (MPIOs). The MPIOs were essentially inert with respect to cell proliferation and tumor formation. Fluorescence stereomicroscopy and three dimensional magnetic resonance imaging (MRI) determined that subcutaneous, intramuscular or orthotopically implanted labeled cancer cells could be imaged, in vivo, despite in some cases being undetectable by manual palpation. The MPIO-labeled cancer cells could also be imaged, in vivo, at least 6 weeks after implantation. The fluorescent MPIOs further allowed for the ex vivo identification of tumors cells from histological sections. This study demonstrates the feasibility of using fluorescent MPIOs in prostate and breast cancer cell lines as both a negative contrast agent for in vivo MRI as well as a fluorescent tumor marker for optical imaging in vivo and ex vivo.

Animals↗

PubMed2006

Trypanosoma cruzi infection induces proliferation of vascular smooth muscle cells.

Trypanosoma cruzi infection causes cardiomyopathy and vasculopathy. Previous studies have demonstrated that infection of human umbilical vein endothelial and smooth muscle cells resulted in activation of extracellular signal-regulated kinase (ERK). In the present study, smooth muscle cells were infected with trypomastigotes, and immunoblot analysis revealed an increase in the expression of cyclin D1 and proliferating cell nuclear antigen (PCNA), important mediators of smooth muscle cell proliferation. Interestingly, after infection, the expression of caveolin-1 was reduced in both human umbilical vein endothelial cells and smooth muscle cells. Immunoblot and immunohistochemical analyses of lysates of carotid arteries obtained from infected mice revealed increased expression of PCNA, cyclin D1, its substrate, phospho-Rb (Ser780), and phospho-ERK1/2. The expression of the cyclin-dependent kinase inhibitor p21(Cip1/Waf1), caveolin-1, and caveolin-3 was reduced in carotid arteries obtained from infected mice. There was an increase in the abundance of pre-pro-endothelin-1 mRNA in the carotid artery and aorta from infected mice. The ET(A) receptor was also elevated in infected arteries. ERK activates endothelin-1, which in turn exerts positive feedback activating ERK, and cyclin D1 is a downstream target of both endothelin-1 and ERK. There was significant incorporation of bromodeoxyuridine into smooth muscle cell DNA when treatment was with conditioned medium obtained from infected endothelial cells. Taken together, these data suggest that T. cruzi infection stimulates smooth muscle cell proliferation and is likely a result of the upregulation of the ERK-cyclin D1-endothelin-1 pathway.

Animals↗

PubMed2006

Construction of a novel DNA decoy that inhibits the oncogenic beta-catenin/T-cell factor pathway.

The oncogenic beta-catenin/T-cell factor (TCF) signal is a common trigger inducing expressions of various cancer-related genes and is activated in various types of human malignancy. The aim of this study was to create an effective double-stranded DNA decoy that would interfere with endogenous TCF hyperactivity in tumor cells. We first established the TCF-activated model using nontumor human embryonic kidney 293 (HEK293) cells by introducing a beta-catenin cDNA. Based on a consensus TCF-binding sequence in the cyclin D1 and c-myc promoters, several double-stranded oligodeoxynucleotides were designed and tested for their ability to inhibit TCF activity in the HEK293 model. Among them, the 18-mer oligodeoxynucleotide stably formed double-stranded DNA and efficiently inhibited TCF activity. FITC-labeled oligodeoxynucleotide was efficiently incorporated into the nucleus at 6 hours and remained within cells for up to 72 to 96 hours. When compared with scrambled oligodeoxynucleotide, we found that the 18-mer TCF decoy significantly inhibited TCF activity and promoter activities of the downstream target genes, such as cyclin D1, c-myc, and matrix metalloproteinase 7 in HCT116 colon cancer cells. Reverse transcription-PCR assays indicated that mRNA expression of these genes decreased with treatment of the TCF decoy. Proliferation assay showed that the TCF decoy significantly inhibited growth of HCT116 tumor cells, but not of nontumor HEK293 cells. Our data provide evidence that the TCF decoy reduced both TCF activity and transcriptional activation of downstream target genes. Thus, this TCF decoy is potentially an efficient and nontoxic molecular targeting therapy for controlling malignant properties of cancer cells.

Base Pair Mismatch↗

PubMed2005

beta-catenin signaling and regulation of cyclin D1 promoter in NRK-49F cells transformed by down-regulation of the tumor suppressor lysyl oxidase.

Lysyl oxidase is the enzyme that is essential for collagen and elastin cross-linking. Previous investigations showed that lysyl oxidase is down-regulated in many human tumors and ras-transformed cells. Recently, we proved that antisense down-regulation of lysyl oxidase in NRK-49F cells induced phenotypic changes and oncogenic transformation, characterized by p21(ras) activation and beta-catenin/cyclin D1 up-regulation. In the present paper, we examined beta-catenin intracellular distribution and its association with E-cadherin. We observed an increased association between E-cadherin and beta-catenin in the lysyl-oxidase down-regulated cells during serum starvation. Moreover, we found that beta-catenin cytoplasmic and nuclear levels were increased, suggesting a failure of its down-regulation by the APC-GSK-3beta system, in particular the GSK-3beta phosphorylation of ser-33/37 and thr-41 of beta-catenin. Finally, we investigated the mechanisms leading to the observed cyclin D1 up-regulation. We showed that in the antisense lysyl oxidase cells the cyclin D1 promoter was activated through the LEF and the ATF/CRE sites in the proximal promoter. While the promoter activation through LEF is compatible with beta-catenin signaling, we investigated the possibility that the CRE-dependent activation might be linked to the down-regulation of lysyl oxidase. In fact, up-regulation of lysyl oxidase in a COS-7 cell model showed a significant diminution of the CREB protein binding to the cyclin D1 promoter, leading to a dramatic inhibition of its activity and a significant down-regulation of cyclin D1 protein level in vivo. Finally, our study describes some major anomalies occurring in lysyl oxidase down-regulated fibroblasts, related to beta-catenin signaling and cyclin D1 expression.

Animals↗

PubMed2005

Cyclin D1 antagonizes BRCA1 repression of estrogen receptor alpha activity.

The cyclin D1 gene is frequently overexpressed in human breast cancer and is capable of inducing mammary tumorigenesis when overexpressed in transgenic mice. The BRCA1 breast tumor susceptibility gene product inhibits breast cancer cellular growth and the activity of several transcription factors. Herein, cyclin D1 antagonized BRCA1-mediated repression of estrogen receptor alpha (ERalpha)-dependent gene expression. Cyclin D1 repression of BRCA1 function was mediated independently of its cyclin-dependent kinase, retinoblastoma protein, or p160 (SRC-1) functions in human breast and prostate cancer cells. In vitro, cyclin D1 competed with BRCA1 for ERalpha binding. Cyclin D1 and BRCA1 were both capable of binding ERalpha in a common region of the ERalpha hinge domain. A novel domain of cyclin D1, predicted to form a helix-loop-helix structure, was required for binding to ERalpha and for rescue of BRCA1-mediated ERalpha transcriptional repression. In chromatin immunoprecipitation assays, 17beta-estradiol (E2) enhanced ERalpha and cyclin D1 recruitment to an estrogen response element (ERE). Cyclin D1 expression enhanced ERalpha recruitment to an ERE. E2 reduced BRCA1 recruitment and BRCA1 expression inhibited E2-induced ERalpha recruitment at 12 hours. Cyclin D1 expression antagonized BRCA1 inhibition of ERalpha recruitment to an ERE, providing a mechanism by which cyclin D1 antagonizes BRCA1 function at an ERE. As cyclin D1 abundance is regulated by oncogenic and mitogenic signals, the antagonism of the BRCA1-mediated ERalpha repression by cyclin D1 may contribute to the selective induction of BRCA1-regulated target genes.

Binding, Competitive↗

PubMed2005

Tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces cell proliferation in normal human bronchial epithelial cells through NFkappaB activation and cyclin D1 up-regulation.

Cigarette smoke contains several carcinogens known to initiate and promote tumorigenesis as well as metastasis. Nicotine is one of the major components of the cigarette smoke and the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a tobacco-specific carcinogen. Here, we demonstrated that NNK stimulated cell proliferation in normal human bronchial epithelial cells (NHBE) and small airway epithelial cells (SAEC). Cells exposed to NNK resulted in an increase in the level of cyclin D1 protein (as early as 3-6 h). Increased phosphorylation of the Rb Ser(795) was detected at 6-15 h after NNK treatment and thereby promoted cells entering into the S phase (at 15-21 h). The increased cyclin D1 protein level was induced through activation of the transcription factor, nuclear factor kB (NFkappaB), in the NHBE cells. Treatment of the NHBE cells with PD98059, an ERK1/2 (extracellular signal-regulated protein kinase)-specific inhibitor, specifically suppressed the NNK-induced IkappaBalpha phosphorylation at position 32 of the serine residue, suggesting that the ERK1/2 kinase was involved in the IkappaBalpha phosphorylation induced by NFkappaB activation. To determine whether the NNK-induced NFkappaB activation and cyclin D1 induction were also observed in vivo, A/J mice were treated with NNK (9.1 mg) for 20 weeks and the results showed a significant induction of cyclin D1 and NFkappaB translocation determined by immunoblotting analyses. We further demonstrated that the nicotine acetylcholine receptor (nAchR), which contains the alpha3-subunit, was the major target mediating NNK-induced cyclin D1 expression in the NHBE cells. In summary, our findings demonstrate for the first time that NNK could stimulate normal human bronchial cell proliferation through activation of the NFkappaB, which in turn up-regulated the cyclin D1 expression.

Bronchi↗

PubMed2005

A study of cytotoxic synergy of UCN-01 and flavopiridol in syngeneic pair of cell lines.

Flavopiridol and UCN-01 are two novel protein kinase inhibitors with diverse cellular effects that may complement each other with regards to induction of apoptosis. HeLa cells engineered to overexpress human survivin (HeLa-S) were at least approximately 4.8-fold resistant to UCN-01 relative to proliferation observed in control HeLa cells (HeLa-V). Flavopiridol cytotoxicity as measured using the MTT assay was unaffected in HeLa-S cells when compared with HeLa-V cells. Similarly, simultaneous treatment of HeLa-V cells with flavopiridol and UCN-01 for 72 hours did not result in synergistic inhibition of proliferation; however, in HeLa-S cells, this combination resulted in synergistic inhibition of cell proliferation. Flavopiridol and UCN-01 augmented apoptosis in HeLa-S cells (as compared with HeLa-V cells) as measured by caspase-3 cellular activity assay, DNA fragmentation and PARP cleavage by western blot. In HeLa-V and -S cells, combination treatment resulted in caspase-8 cleavage. Caspase-9 was expressed in HeLa-V cells; however, there was a marked reduction of caspase-9 content in HeLa-S cells only. Combination treatment resulted in a significant reduction in survivin abundance in HeLa-S and SKBR3-UR cells, but not in their respective parental lines. The synergy of Flavopiridol and UCN-01 are selectively toxic to survivin-overexpressing cell lines and the mechanism of toxicity involves caspase-dependent cell death.

Antineoplastic Agents↗

PubMed2005

Increased cyclin E expression may obviate the role of cyclin D1 during brain development in cyclin D1 knockout mice.

Cyclins D and E play critical roles during the G1 phase of mammalian cell division. Cyclin D1 expression is high and expected to play an important role during mouse brain development. However, in the present study, we found no difference in CNS morphology between cyclin D1 knockout (KO) and control wild-type mice at the ages of 1, 4 and 12 months. Analysis of protein expression in embryonic brains revealed that cyclin E is obviously increased in cyclin D1 KO mice at 13.5 days post coitum. At the same age a high level of cyclin D1 expression is detected in the embryonic brain of wild-type mice. The data indicate that enhanced cyclin E protein expression in cyclin D1 KO mice may obviate the role of cyclin D1 and contribute to the normal brain development of cyclin D1 KO mice.

Animals↗

PubMed2005

Differential effects of 16alpha-hydroxyestrone and 2-methoxyestradiol on cyclin D1 involving the transcription factor ATF-2 in MCF-7 breast cancer cells.

We studied the effects of 2-methoxyestradiol (2-ME2) and 16alpha-hydroxyestrone (16alpha-OHE1), two metabolites of estradiol (E2), on DNA synthesis, cell cycle progression and cyclin D1 protein levels in estrogen receptor-positive MCF-7 cells. E2 and 16alpha-OHE1 stimulated DNA synthesis, and 2-ME2 inhibited the stimulatory effects of these agents. E2 and 16alpha-OHE1 stimulated the progression of cells from G1 to S phase and this effect was attenuated by 2-ME2. Western blot analysis showed that E2 and 16alpha-OHE1 increased cyclin D1 protein level by about fourfold compared with control. 2-ME2 had no significant effect on cyclin D1; however, it prevented the accumulation of cyclin D1 in the presence of E2 and 16alpha-OHE1. Cells transfected with a cyclin D1 reporter gene and treated with E2 or 16alpha-OHE1 showed 7- and 9.5-fold increase respectively in promoter activity compared with control. This activity was significantly inhibited by 2-ME2. Cyclin D1 transactivation was mediated by the cAMP response element (CRE) region, which binds activating transcription factor 2 (ATF-2). DNA affinity assay showed 2.5- and 3.5-fold increases in ATF-2 binding to CRE in the presence of E2 and 16alpha-OHE1 respectively. The binding of ATF-2 was inhibited by the presence of 2-ME2. These results show that 2-ME2 can downregulate cyclin D1 and thereby cell cycle progression by a mechanism involving the disruption of ATF-2 binding to cyclin D1 promoter.

2-Methoxyestradiol↗

PubMed2005

Activation of cyclin D1 by estradiol and spermine in MCF-7 breast cancer cells: a mechanism involving the p38 MAP kinase and phosphorylation of ATF-2.

Estradiol (E2) and the naturally occurring polyamines (putrescine, spermidine, and spermine) play important roles in breast cancer cell growth and differentiation. We examined the effects of E2 and spermine on the phosphorylation and DNA binding of activating transcription factor-2 (ATF-2) in MCF-7 breast cancer cells. ATF-2 is a transcription factor involved in estrogenic regulation of cyclin D1 gene, and thereby cell cycle progression. DNA affinity immunoblot assays showed a six- to eightfold increase in the binding of ATF-2 to a 74-mer ATF/CRE oligonucleotide (ODN1) from cyclin D1 promoter in the presence of 4 nM E2 and 0.5 mM spermine, compared to untreated control. Individual treatments with E2 or spermine caused a twofold or lower increase in ATF-2 binding to ODN1. Immunoblotting with phospho-ATF-2 antibody showed that increased DNA binding of ATF-2 was associated with its phosphorylation. A p38 MAP kinase inhibitor, PD169316, inhibited ATF-2 phosphorylation. In contrast, the MEK-ERK1/2 inhibitor, PD98059, or the JNK inhibitor, SP600125, had no significant effect on DNA binding of ATF-2. Cyclin D1 promoter (-1745CD1) activity increased by approximately 12-fold (above control) in the presence of E2 and spermine, compared to a sixfold increase in the presence of E2 alone and a twofold increase with spermine. Cells transfected with a dominant negative mutant of ATF-2 showed decreased transactivation of cyclin D1 promoter in response to E2 and spermine. These results indicate that spermine can enhance E2-induced cell signaling and cyclin D1 transcription by activation of the p38 MAP kinase and phosphorylation of ATF-2, contributing to breast cancer cell proliferation.

Activating Transcription Factor 2↗

PubMed2004

The inhibitor of cyclin-dependent kinase 4a/alternative reading frame (INK4a/ARF) locus encoded proteins p16INK4a and p19ARF repress cyclin D1 transcription through distinct cis elements.

The Ink4a/Arf locus encodes two structurally unrelated tumor suppressor proteins, p16(INK4a) and p14(ARF) (murine p19(ARF)). Invariant inactivation of either the p16(INK4a)-cyclin D/CDK-pRb pathway and/or p53-p14(ARF) pathway occurs in most human tumors. Cyclin D1 is frequently overexpressed in breast cancer cells contributing an alternate mechanism inactivating the p16(INK4a)/pRb pathway. Targeted overexpression of cyclin D1 to the mammary gland is sufficient for tumorigenesis, and cyclin D1-/- mice are resistant to Ras-induced mammary tumors. Recent studies suggest cyclin D1 and p16(INK4a) expression are reciprocal in human breast cancers. Herein, reciprocal regulation of cyclin D1 and p16(INK4a) was observed in tissues of mice mutant for the Ink4a/Arf locus. p16(INK4a) and p19(ARF) inhibited DNA synthesis in MCF7 cells. p16(INK4a) repressed cyclin D1 expression and transcription. Repression of cyclin D1 by p16(INK4a) occurred independently of the p16(INK4a)-cdk4-binding function and required a cAMP-response element/activating transcription factor-2-binding site. p19(ARF) repressed cyclin D1 through a novel distal cis-element at -1137, which bound p53 in chromatin-immunoprecipitation assays. Transcriptional repression of the cyclin D1 gene through distinct DNA sequences may contribute to the tumor suppressor function of the Ink4a/Arf locus.

Animals↗

PubMed2004

Gastrin-mediated activation of cyclin D1 transcription involves beta-catenin and CREB pathways in gastric cancer cells.

Gastrin and its precursors promote proliferation in different gastrointestinal cells. Since mature, amidated gastrin (G-17) can induce cyclin D1, we determined whether G-17-mediated induction of cyclin D1 transcription involved Wnt signaling and CRE-binding protein (CREB) pathways. Our studies indicate that G-17 induces protein, mRNA expression and transcription of the G(1)-specific marker cyclin D1, in the gastric adenocarcinoma cell line AGSE (expressing the gastrin/cholecystokinin B receptor). This was associated with an increase in steady-state levels of total and nonphospho beta-catenin and its nuclear translocation, indicating the activation of the Wnt-signaling pathway. In addition, G-17-mediated increase in cyclin D1 transcription was significantly attenuated by axin or dominant-negative (dn) T-cell factor 4(TCF4), suggesting crosstalk of G-17 with the Wnt-signaling pathway. Mutational analysis indicated that this effect was mediated through the cyclic AMP response element (CRE) (predominantly) and the TCF sites in the cyclin D1 promoter, which was also inhibited by dnCREB. Furthermore, G-17 stimulation resulted in increased CRE-responsive reporter activity and CREB phosphorylation, indicating an activation of CREB. Chromatin immunoprecipitation studies revealed a G-17-mediated increase in the interaction of beta-catenin with cyclin D1 CRE, which was attenuated by dnTCF4 and dnCREB. These results indicate that G-17 induces cyclin D1 transcription, via the activation of beta-catenin and CREB pathways.

Cyclic AMP Response Element-Binding Protein↗

PubMed2004

Trypanosoma cruzi infection activates extracellular signal-regulated kinase in cultured endothelial and smooth muscle cells.

Trypanosoma cruzi infection causes cardiomyopathy and vasculopathy. We examined the consequence of this infection for the mitogen-activated protein kinase (MAPK) pathways, which regulate cell proliferation in cultured human umbilical vein endothelial and vascular smooth muscle cells. Infection of these cells resulted in activation of extracellular signal-regulated kinases 1and 2 (ERK1/2) but not c-Jun N-terminal kinase or p38 MAPK. Treatment of these cells with the MAPK kinase inhibitor PD98059 prior to infection blocked the increase in phosphorylated ERK1/2 seen with infection. Heat-killed parasites did not activate ERK1/2, indicating that activation of ERK1/2 was dependent on infection of these cells by live parasites. Furthermore, transfection with dominant-negative Raf(301) or Ras(N17) constructs reduced the infection-associated levels of phospho-ERK1/2, indicating that the activation of ERK1/2 involved the Ras-Raf-ERK pathway. Infection also resulted in an increase in activator protein 1 (AP-1) activity, which was inhibited by transfection with a dominant-negative Raf(301) construct. T. cruzi-infected endothelial cells secreted endothelin-1 and interleukin-1beta, which activated ERK1/2 and induced cyclin D1 expression in uninfected smooth muscle cells. These data suggest a possible molecular paradigm for the pathogenesis of the vasculopathy and the cardiovascular remodeling associated with T. cruzi infection.

Animals↗

PubMed2004

Cyclin D1 genetic heterozygosity regulates colonic epithelial cell differentiation and tumor number in ApcMin mice.

Constitutive beta-catenin/Tcf activity, the primary transforming events in colorectal carcinoma, occurs through induction of the Wnt pathway or APC gene mutations that cause familial adenomatous polyposis. Mice carrying Apc mutations in their germ line (ApcMin) develop intestinal adenomas. Here, the crossing of ApcMin with cyclin D1-/- mice reduced the intestinal tumor number in animals genetically heterozygous or nullizygous for cyclin D1. Decreased tumor number in the duodenum, intestines, and colons of ApcMin/cyclin D1+/- mice correlated with reduced cellular proliferation and increased differentiation. Cyclin D1 deficiency reduced DNA synthesis and induced differentiation of colonic epithelial cells harboring mutant APC but not wild-type APC cells in vivo. In previous studies, the complete loss of cyclin D1 through homozygous genetic deletion conveyed breast tumor resistance. The protection of mice, genetically predisposed to intestinal tumorigenesis, through cyclin D1 heterozygosity suggests that modalities that reduce cyclin D1 abundance could provide chemoprotection.

Adenomatous Polyposis Coli Protein↗