Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using monoclonal antibodies against the RAR-alpha and RAR-beta retinoic receptors, we demonstrated that these receptors were present together in C6 glioma cells as two isoforms of 50 and 55 kDa. For RAR-beta, the 50 kDa isoform predominated (60 to 80% of the total of the two isoforms). After a treatment for 48 h with retinoic acid 10 microM, the 55 kDa form was enhanced, while no effect was observed either on RAR-alpha isoforms from C6 cells and on both RAR-alpha and RAR-beta forms from neuroblastoma SKN SH SY5Y used as a control. Using purified neuronal and glial rat brain nuclei, we showed that the 55 kDa isoform from RAR-beta predominated in glial cells. These results suggest that retinoic acid treatment of C6 cells led to a partial differentiation, the enhancement of the heavy form of RAR-beta being a marker of this phenomenon.
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PMID:Study of retinoic acid effect upon retinoic acid receptors beta (RAR-beta) in C6 cultured glioma cells. 758 Oct 5

Neuroblastoma cells differentiate in response to retinoic acid and cyclic AMP. We have examined the expression of retinoic acid receptors (RARs) in relation to neuroblastoma differentiation and show that short term exposure of SK N SH, SH SY 5Y AND GI LI N cells to physiological concentrations of retinoic acid results in induction of RAR-beta, particularly the lower transcript. Cyclic AMP has no effect on retinoic acid mediated induction and does not alter RAR expression patterns. These data are discussed in the light of evidence that retinoic acid and cyclic AMP act either on different control pathways or at different points within a common pathway.
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PMID:Retinoic acid receptor expression during the in vitro differentiation of human neuroblastoma. 812 10

To date, the clinical success of 13-cis or all-trans retinoic acid in the treatment of neuroblastoma has been disappointing. In vivo, 13-cis will isomerise to both all-trans and 9-cis retinoic acid, believed to be the main biologically-active isomers. In vitro studies with an N-type neuroblastoma cell line, SH SY 5Y, show that 9-cis is better than other isomers at both inducing morphological differentiation and inhibiting proliferation. RAR-beta, a gene which may mediate retinoic acid responsiveness and be of prognostic significance, is also more-effectively induced by 9-cis retinoic acid. 9-cis and all-trans retinoic acid do not have synergistic effects on SH SY 5Y cell proliferation and gene expression. A retinoid X receptor (RXR)-specific analogue of 9-cis retinoic acid had similar effects on gene expression to 9-cis retinoic acid alone. In view of these results, 9-cis retinoic acid or stable analogues of this retinoid may have potential for the treatment of neuroblastoma.
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PMID:9-cis retinoic acid--a better retinoid for the modulation of differentiation, proliferation and gene expression in human neuroblastoma. 904 33

We investigated the potential for 9-cis-retinoic acid in the differentiation therapy of neuroblastoma using an N-type neuroblastoma cell line, SH SY 5Y, as an experimental model. In these cells, 9-cis-retinoic acid is more effective than other isomers at inducing the expression of RAR-beta. An RAR-alpha-specific antagonist inhibited the induction of RAR-beta in response to all-trans-but not to 9-cis-retinoic acid. This indicates that the mechanism of gene induction by 9-cis-retinoic acid differs markedly from all-trans-retinoic acid. 9-cis-retinoic acid is also better than all-trans at producing sustained morphological differentiation and inhibition of proliferation of SH SY 5Y cells. Although N-type neuroblastoma cells are not thought to undergo apoptosis in response to all-trans-retinoic acid, we observed a significant degree of apoptosis in SH SY 5Y cells treated with 9-cis-retinoic acid for 5 days and then cultured in the absence of retinoid, an effect not observed in cells treated with the all-trans isomer. These results suggest that 9-cis- and all-trans-retinoic acid have distinct biological properties and that 9-cis retinoic acid may be clinically effective in neuroblastoma by inducing both differentiation and apoptosis under an appropriate treatment regimen.
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PMID:Retinoids in neuroblastoma therapy: distinct biological properties of 9-cis- and all-trans-retinoic acid. 951 56

The aim of this study was to investigate in vitro the effects of all-trans retinoic acid (RA), 9-cis RA and the RXR-selective analogue, LG69, on the morphological differentiation, proliferation and gene expression of neuroblastoma cells. Three different cell lines were cultured with the retinoid for either 9 continuous days or for 5 days followed by 4 days without the retinoid and morphological differentiation was assessed both qualitatively and quantitatively. SH SY 5Y cell proliferation was examined by measuring cell numbers after exposure to the retinoids and RAR-beta gene expression was examined by Northern blot analysis. Morphological differentiation was more effectively induced by all-trans and 9-cis RA than by LG69. SH SY 5Y cells, when treated with 9-cis RA for only 5 of the 9 days of culture, underwent apoptosis, but this was not seen with 9 days continuous exposure nor with LG69. Inhibition of SH SY 5Y cell proliferation by all-trans or 9-cis RA was dose-dependent, but LG69 had little effect. Conversely, LG69 induced higher expression of RAR-beta than all-trans RA, but less than that produced by 9-cis RA. These data suggest that 9-cis RA as a single agent is the most effective modulator of neuroblastoma behaviour and may be the most appropriate therapeutic agent.
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PMID:Retinoid-induced differentiation of neuroblastoma: comparison between LG69, an RXR-selective analogue and 9-cis retinoic acid. 962 47

Retinoids modulate several cell functions and especially inhibit the growth of tumor cells. Their biological activity is mediated by retinoic acid receptors (RARs), of which three subtypes (alpha, beta, gamma) have been identified. In human neuroblastoma (NB) reduced endogenous RAR-gamma expression was suggested to diminish the sensitivity for retinoids, to promote proliferation, and to contribute to the malignant phenotype. To correlate receptor selectivity with in vitro activity, we analysed the effect of six synthetic retinoids with selectivity for human RAR-alpha/beta/gamma on the human LAN-5 NB cell line and compared it with the natural compound all-trans-retinoic acid (ATRA). Apoptosis was determined by flow-cytometry using terminal-deoxynucleotidyl transferase to end-label DNA fragments in situ in apoptotic cells. The antagonist for RAR-beta/gamma CD2665 as well as the selective agonists for RAR-alpha CD336 and RAR-beta CD2019 were less effective in growth inhibition than ATRA. In contrast, the synthetic RAR-gamma selective agonists CD437 and CD2325 induced a concentration- and time-dependent antiproliferative effect, which was similar or even more pronounced than ATRA. In contrast to ATRA, the adition of CD437 and CD2325 did not induce morphological changes typical of NB cell maturation but resulted in morphological features consistent with the occurrence of programmed cell death. Flow-cytometric analysis showed that in contrast to ATRA the addition of CD 437 and CD 2325 results in progressive time-dependent increase of apoptotic cells (25.9% and 57.7% after 72 hours). In conclusion, our study demonstrates RAR-gamma selectively binding retinoids dramatically suppress NB cell growth, primarily by inducing programmed cell death rather than by cell differentiation. Since advanced or disseminated NB tumors endogenously express low levels of RAR-gamma and lack of apoptosis is involved in tumor progression, RAR-gamma selectively binding retinoids may be more appropriate retinoids for clinical trials in NB.
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PMID:Antiproliferative activity and apoptosis induced by retinoic acid receptor-gamma selectively binding retinoids in neuroblastoma. 967 4

Treatment with 13-cis retinoic acid (13-cis RA) has been shown to significantly improve the clinical outcome of children with high-risk neuroblastoma. Despite the large number of studies investigating the cellular effects of retinoids in neuroblastoma cells, the influence of RA isomerisation and the factors that determine the extent of RA isomerisation and uptake are unknown. The aim of this study was to establish the extent of extra- and intracellular isomerisation of 13-cis RA and all-trans retinoic acid (ATRA) in neuroblastoma cell lines, and to investigate the influence of isomerisation on their growth inhibitory effects and on the regulation of expression of cellular retinoic acid binding protein II (CRABP II) and RAR-beta. Limited extracellular isomerisation was observed up to 72 hr after incubation of four neuroblastoma cell lines with 10 microM 13-cis RA or ATRA. The retinoic acid isomer present initially in the medium accounted for >75% of extracellular retinoid exposure. By contrast, incubation with 13-cis RA resulted in intracellular levels of ATRA comparable to those of 13-cis RA. This degree of intracellular isomerisation was not observed after ATRA incubations, with 13-cis RA accounting for <10% of total intracellular retinoids. No differences were observed in the sensitivity of three N-type neuroblastoma cell lines to either 13-cis RA (IC(50): 11.2-13.9 microM) or ATRA (IC(50): 12.9-14.4 microM), despite 10-fold differences in intracellular retinoid levels. A decrease in sensitivity to 13-cis RA (IC(50)=137 microM), as compared to ATRA (IC(50)=41 microM), was observed in the S-type cell line SH S EP. RAR-beta was induced in a dose-dependent manner in SH SY 5Y cells following incubation with ATRA, whereas a weaker and delayed induction was observed with 13-cis RA. Similarly, incubation with ATRA resulted in a greater induction of CRABP II in these cells. In summary, these results indicate either an intracellular conversion of 13-cis RA to ATRA or a selective uptake of ATRA and suggest that this may mediate the differential activity of 13-cis RA in neuroblastoma cell subtypes.
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PMID:Influence of isomerisation on the growth inhibitory effects and cellular activity of 13-cis and all-trans retinoic acid in neuroblastoma cells. 1184 95