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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Retinoic acid (RA) can promote human medulloblastoma cells Med-3 toward differentiation but is not sufficient to induce cell death, suggesting its limited effect on medulloblastomas. On the other hand, the differentiated tumour cells have been supposed to be more sensitive to chemotherapeutic drugs. To elucidate this possibility for medulloblastoma cells, 10 microM/l RA, 1.0 microg/ml cisplatin (CP) and their half-dosage combinations were utilized in this study to treat Med-3 cells and their influences in cell proliferation, morphology and death patterns were evaluated. In parallel, the expressions of Fas and its ligand (FasL) were analyzed by immunocytochemical staining and Western blot hybridization. Anti-Fas antibody was used to incubate the Med-3 cells pretreated by 10 microM/l RA or 1.0 microg/ml CP. It was revealed that RA and CP could inhibit cell growth but rarely induce apoptosis. Combination of half doses each of RA and CP effectively caused most of tumour cells to die of apoptosis within 6 days. FasL molecules in 29 kDa and 37 kDa were detected in Med-3 cells with and without the treatments. The Fas molecule around 30 kDa and located in the cytoplasm was found in the normally cultured cells and the cells treated by CP. An additional 45 kDa Fas band with the appearance of its cell surface labeling was detected in the cells treated by 10 microM/l RA and by 5 microM/l RA + 0.5 microg/ml CP. The anti-Fas antibody could efficiently induce apoptosis only in the cell populations pretreated by RA. Our data thus suggest that RA can enhance the chemosensitivity of human medulloblastoma Med-3 cells presumably via modulating the Fas expression pattern. The RA/CP combined regimen would be a potential therapeutic approach for medulloblastomas.
Int J Mol Med 2000 Feb
PMID:All-trans retinoic acid modulates fas expression and enhances chemosensitivity of human medulloblastoma cells. 1063 92

Retinoic acid (RA) and sodium butyrate (NaB) are regulators of cell growth and differentiation. We studied their effect on normal (SVC1) or v-Ki-ras-transformed (Ki-SVC1) rat seminal vesicle (SV) epithelial cell lines. The treatment of these cells with 10(-((7( M RA did not produce significant changes in the morphological and biochemical parameters analyzed. When RA was used in combination with 2 mM NaB, the treatment induced substantial morphological changes, apoptosis-independent growth arrest, up-regulation of tissue transglutaminase (tTGase), and down-regulation of beta and gamma RA receptor (RAR) mRNA expression. The same cells did not express RAR alpha either before or after NaB/RA treatment. A similar treatment did not change the amount of mRNA coding for the protein SV-IV (a typical differentiation marker of the SV epithelium) in normal or ras-transformed cells nor the level of v-Ki-ras mRNA in Ki-SVC1 cells. These findings suggest that a defective RA/RARs signaling pathway is probably the biochemical condition that underlies the unresponsiveness to RA of our in vitro culture system, and indirectly points to the possibility that the NaB/RA-induced effects were brought about by a cooperation at the transcription level between the histone deacetylase inhibitory activity of NaB and the ability of RA/RAR to modulate the expression of various genes involved in the control of cell growth and differentiation.
J Mol Endocrinol 2000 Feb
PMID:Sodium butyrate/retinoic acid costimulation induces apoptosis-independent growth arrest and cell differentiation in normal and ras-transformed seminal vesicle epithelial cells unresponsive to retinoic acid. 1065

We have shown that moderately differentiated endometrial adenocarcinoma (RL95-2) cells differentiate in response to retinoic acid treatment, illustrated by their reorganization of actin filaments and cell enlargement (Carter et al., Anticancer Res. 16, 17-24, 1996). Tyrphostin, an inhibitor of epidermal growth factor receptor (EGF-R)-associated protein tyrosine kinases, caused a dramatic reorganization of actin filaments in RL95-2 cells, similar to retinoic-acid-treated cells (Carter and Bellido, J. Cell. Physiol. 178, 320-332, 1999). We evaluated the possibility that the differentiating effects of retinoids are due to retinoic-acid-induced decreases in phosphorylation of EGF-R and changes in downstream effector proteins. Retinoic acid caused a decrease in tyrosine phosphorylation of EGF-R. Retinoic acid treatment induced a dramatic actin filament reorganization and cell enlargement. Treatment with EGF reversed this effect, because cells treated with retinoic acid followed by EGF only possessed disrupted actin aggregates and appeared small, thus resembling medium controls. Retinoic acid induced a relocalization and decrease in the amount of Shc protein, another actin-binding protein which is an adaptor protein for EGF-R signaling. In addition, retinoic acid induced a relocalization of gelsolin from the plasma membrane to the cytoplasm. Retinoic acid decreased cell detachment in detachment assays; one-half as many retinoic-acid-treated cells detached as in controls. These results are consistent with the idea that retinoic acid induces differentiation of RL95-2 cells by interfering with the EGF-R signaling pathway.
Exp Mol Pathol 2000 Jun
PMID:Retinoic acid affects the EGF-R signaling pathway during differentiation induction of human endometrial adenocarcinoma cells. 1081 85

Retinoic acid (RA) is required for diverse developmental programs, including vertebral specification. Both RA receptor disruption and excess RA result in homeotic transformations of the axial skeleton. These effects are believed to occur through altered expression of Hox genes, several of which have been demonstrated to be direct RA targets. Members of the cdx (caudal) homeobox gene family are also implicated in regulating Hox expression. Disruption of cdx1 results in vertebral homeotic transformations and alteration of Hox expression boundaries; similar homeosis is also observed in cdx2 heterozygotes. In Xenopus, gain or loss of Cdx function affects vertebral morphogenesis through a mechanism that also correlates with altered Hox expression. Taken together with the finding of putative Cdx binding motifs in several Hox promoters, these data strongly support a role for Cdx members in direct regulation of expression of at least some Hox genes. Most retinoid-responsive Hox genes have not been demonstrated to be direct RA targets, suggesting that intermediaries are involved. Based on these findings, we hypothesized that one or more cdx members may transduce the effects of RA on Hox transcription. Consistent with this, we present evidence that cdx1 is a direct RA target gene, suggesting an additional pathway for retinoid-dependent vertebral specification.
Mol Cell Biol 2000 Sep
PMID:Retinoic acid regulation of Cdx1: an indirect mechanism for retinoids and vertebral specification. 1093 32

Retinoic acid (RA) induces the differentiation of F9 cells cultured as monolayers into primitive endodermal-like cells, whereas a combination of RA and cAMP leads to parietal endodermal differentiation. In RA receptor alpha-null F9 cells (RARalpha-/- cells), RA still efficiently triggers RARgamma-mediated primitive endodermal differentiation, but parietal endodermal differentiation is markedly delayed. To investigate the role of RARalpha1 activation functions AF-1 and AF-2 and of their phosphorylation sites during RA- and cAMP-induced parietal differentiation, cell lines reexpressing WT or mutated RARalpha1 were established in RARalpha-/- cells. We have found that the protein kinase A (PKA) phosphorylation site and the AF-2AD core (helix 12) of RARalpha1 are required for efficient parietal endodermal differentiation, whereas the AF-1 proline-directed kinase phosphorylation site is dispensible. Interestingly, deletion of the AF-1 activating domain (the A/B region), but not of the AF-2AD core, generates a dominant negative mutant that abrogates primitive endodermal differentiation when expressed in RARalpha-/- cells. We also show that the RARalpha AF-1 and AF-2 activation functions, but not their phosphorylation sites, are involved in the induction of RA-responsive genes in a differential promoter context-dependent manner.
Mol Endocrinol 2000 Sep
PMID:The AF-1 and AF-2 activating domains of retinoic acid receptor-alpha (RARalpha) and their phosphorylation are differentially involved in parietal endodermal differentiation of F9 cells and retinoid-induced expression of target genes. 1097 18

Murine models of human neoplasms are being used to expand our understanding of pathogenesis and to develop improved cancer therapies. MRP8-PMLRARalpha transgenic mice represent one model of human acute promyelocytic leukemia (APL). These mice develop leukemias that mirror characteristic features of human APL including responsiveness to retinoic acid and arsenic. This model is proving its value in elucidating mechanisms by which PMLRARalpha contributes to leukemia, identifying genetic changes that cooperate to cause leukemia, and investigating new molecular targets for leukemia therapy. These studies suggest that acute myeloid leukemias (AMLs) such as APL result from genetic changes that combine to both impair differentiation and allow immature cells to survive and proliferate outside of a normal microenvironment. Retinoic acid targets the central molecular lesion in human APL and has greatly improved survival. Molecularly targeted therapies that either restore maturation or abrogate growth autonomy represent a hope for improving survival of patients with other subtypes of AML.
Blood Cells Mol Dis 2000 Dec
PMID:Acute promyelocytic leukemia: a view from a mouse. 1135 54

WNT2 is one of proto-oncogenes to activate the beta-catenin - TCF signaling pathway. WNT2B is a paralogue of WNT2, which encodes WNT2B1 and WNT2B2 isoforms due to alternative splicing using alternative promoter. Here, regulation of WNT2, WNT2B1, and WNT2B2 mRNAs in MCF-7 cells (breast cancer), NT2 cells (teratocarcinoma), and MKN45 cells (gastric cancer) were investigated. WNT2B2, but not WNT2 and WNT2B1, was expressed in MCF-7 cells. beta-estradiol (100 nM) induced a transient up-regulation of WNT2 in MCF-7 cells, and also induced down-regulation of WNT2B2. WNT2B2, but not WNT2B1, was expressed in NT2 cells, and WNT2 was slightly expressed in NT2 cells. Retinoic acid (10 microM) induced a transient up-regulation of WNT2 in NT2 cells. WNT2B2, but not WNT2 and WNT2B1, was slightly expressed MKN45 cells, and tumor necrosis factor alpha did not affect expression of WNT2, WNT2B1, and WNT2B2 mRNAs in MKN45 cells. This is the first report on differential regulation of WNT2, WNT2B1, and WNT2B2 mRNAs in human cancer cell lines. Up-regulation of WNT2 mRNA by estrogen might play a key role in some cases of human breast cancer through activation of the beta-catenin - TCF signaling pathway.
Int J Mol Med 2001 Dec
PMID:Differential regulation of WNT2 and WNT2B expression in human cancer. 1171 82

Proteolytic degradation of extracellular matrix is thought to play an important role both in emphysema and in tissue development and repair. Retinoic acid has been suggested to modify tissue injury, and in an animal model of emphysema may induce alveolar repair. Since cytokines can induce matrix metalloproteinase (MMP) production in fibroblasts and neutrophil elastase (NE) can activate MMPs, we hypothesized that retinoic acid could attenuate collagen degradation by modifying MMP production and activation. To evaluate this, human lung fibroblasts were cast into native type I collagen gels and floated in medium containing cytomix (TNF-alpha, IL-1beta, and IFN-gamma) alone or in combination with NE in the presence and absence of retinoic acid (1 microM). After 5 d, cytomix with elastase induced significant degradation of the collagen gels assessed by quantifying total hydroxyproline (41.6 +/- 1.6 microg versus 3.3 +/- 1.5 microg, P < 0.01). Retinoic acid significantly inhibited this degradation (23.3 +/- 1.5 microg versus 3.3 +/- 1.5 microg, P < 0.01). Gelatin zymography and Western blot revealed that MMP-1, MMP-3, and MMP-9 were induced by cytomix and that co-exposure to NE resulted in increased production of activated forms of these enzymes. Retinoic acid attenuated the induction and activation of MMP-1 and MMP-3. The current study, therefore, suggests that in addition to stimulating anabolic effects, retinoic acid may modulate proteolytic processes thought to contribute to tissue destruction in emphysema.
Am J Respir Cell Mol Biol 2001 Nov
PMID:Retinoic acid attenuates cytokine-driven fibroblast degradation of extracellular matrix in three-dimensional culture. 1171 5

The homozygous mutant mouse staggerer (RORa(sg)/RORa(sg)), was initially described as ataxic, due to the presence of massive neurodegeneration in the cerebellum [Science 136 (1962) 610]. The identification of the widely expressed Retinoic acid receptor-related Orphan Receptor, NR1F1 (RORalpha) gene as the site of mutation in the staggerer mouse has led to great progress in understanding the molecular basis of its phenotype in recent years [Nature 379 (1996) 736]. RORalpha is a transcription factor, belonging to the nuclear receptor superfamily, for which no natural ligand has yet been identified. Mice engineered for the disruption of the gene encoding RORalpha display the same cerebellar atrophic phenotype as the staggerer mouse [Proc. Natl. Acad. Sci. USA 95 (1998) 3960]. More recently, it has been shown that the mutation is semi-dominant, as heterozygous animals display an increased loss of Purkinje cells with age. Furthermore, a number of additional phenotypes outside the nervous system have recently been identified. These include a greater susceptibility to atherosclerosis [Circulation 15 (1998) 2738], immunodeficiencies linked to the overexpression of inflammatory cytokines [J. Neurochem. 58 (1992) 192], abnormalities in the formation and maintenance of bone tissue [Proc. Natl. Acad. Sci. USA 97 (2000) 9197] and changes in muscle differentiation [Nucleic Acids Res. 27 (1999) 411]. Thus, RORalpha has been directly linked to a number of age-related pathologies of great medical interest.
Mol Cell Endocrinol 2002 Jan 15
PMID:Age-related phenotypes in the staggerer mouse expand the RORalpha nuclear receptor's role beyond the cerebellum. 1185 Jan 16

Retinoic acid (RA) induced differentiation of SH-SY5Y cells increases the expression of mu opioid receptors (HMOR) and inhibitory G proteins, as well as the efficacy of opioids to inhibit forskolin-induced adenylyl cyclase activity. We examined the time course of the effects of all-trans retinoic acid (RA) on HMOR and c-fos mRNA levels as determined by solution hybridization (using HMOR and rat c-fos riboprobes) in RNA extracts from SH-SY5Y cells. Electrophoretic Mobility Shift Assay (EMSA) and Western blot analysis were used to assess the changes AP-1 DNA binding and the presence of fos-related proteins in nuclear extracts from untreated, vehicle (ethanol) or RA-treated SH-SY5Y cells. Exposure to RA for 0.5 h had no effect on HMOR while after 6-18 h of exposure HMOR in mRNA levels were decreased by 50% and then after 168 h of RA exposure, HMOR mRNA levels were doubled. In contrast, c-fos mRNA levels were unchanged at 0.5 h, but increased by 50% after 18 and 168 h of RA exposure. RA increased AP-1 binding after 18 and 168 h and a pan fos-FRA antibody produced a supershift. Western analysis indicates that RA activates a 45-kDa protein corresponding to the size of the fos B protein. These results identify two signal transduction targets that are regulated by RA during differentiation.
Brain Res Mol Brain Res 2002 Feb 28
PMID:Retinoic acid regulation of mu opioid receptor and c-fos mRNAs and AP-1 DNA binding in SH-SY5Y neuroblastoma cells. 1186 6


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