Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biochemical, pharmacological and immunological characterization of cells derived from human neuroblastoma tumors recently acquired great interest, since these cells may be a putative donor source for transplantation in animal models of neurological disorders. We measured monoamine levels, tyrosine hydroxylase (TH) immunostaining, and the expression of major histocompatibility cell surface antigens (MHC) in 7 human neuroblastoma cell lines. Three cell lines (LAN5, NB69 and CHP126) had high levels of monoamines. TH immunostaining was strongly positive in CHP126 and LAN5, and NB69. MHC were not detected in any of the cells with high catecholamine levels. Treatment with neuroleptics increased the metabolism of dopamine in LAN5 but not in NB69. The implantation of LAN5 cells in immunocompetent, unilaterally 6-hydroxydopamine-lesioned rats decreased the apomorphine-induced contralateral rotation. The effect of the implant was greatest in animals in which LAN5 neuroblastoma cells, pretreated with dibutyryl cyclic adenosine monophosphate (DBcAMP) and prostaglandin E1 (PGE1, were implanted into the cerebral ventricle ipsilateral to the lesion, and then irrigated with DBcAMP administered through a totally implanted drug delivery system. The effect of the implant decreased after the second week. Neuroblastoma cells were found in approximately 50% of the implanted animals. TH immunostaining was weak or absent in the grafted animals. Inflammatory changes were present in the majority of the brains examined. Extensive tumor growth was present in one animal implanted with untreated cells. Grafting of cells treated with DBcAMP and PGE1 plus with mitomycin C and bromodeoxyuridine in animals immunosuppressed with cyclosporin A reduced the apomorphine-induced rotation to 40-60% of baseline levels and this reduction persisted beyond the period of infusion with DBcAMP. Intraventricular infusion of DBcAMP in animals injected with cell culture medium produced a transient reduction of rotation to 70% of baseline. The amphetamine-induced rotation was not significantly reduced during the 4 weeks follow up. Atypical cells, consistent with surviving neuroblastoma cells, were observed in the brain of all transplanted animals. TH immunostaining was weak or negative in most cases. Human neuroblastoma cells may be an alternative donor tissue for the study of the effects of transplantation in animal models of Parkinson's disease.
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PMID:Biochemical properties of monoamine-rich human neuroblastoma cells. 256 96

The possibility of employing PC12 pheochromocytoma cells for transplantation into the rat brain as a substitute for adrenal chromaffin cells was examined. Cultured PC12 cells were implanted into the striatum of rats and examined after one day to 20 weeks by fluorescence histochemistry and immunocytochemical staining for tyrosine hydroxylase and a surface antigen of PC12 cells. Between 800 and 3000 cells survived the implantation procedure and persisted relatively unchanged for about one week. Long-term survival of small numbers of PC12 cells was observed in nine of 14 animals, although the number of surviving cells was reduced after 7.5-20 weeks as compared to earlier time periods. By 14-20 weeks after implantation, most of the remaining cells had developed processes. In other animals, there appeared to have been an initial large increase in the number of cells, followed by complete death of the graft. In many of these animals with no surviving cells, large deposits of hemosiderin were found at the implantation site, an apparent residue of earlier tumor growth. Thus in some animals, the number of PC12 cells apparently increased initially, but in these animals the graft was ultimately rejected. In other animals, small numbers of PC12 cells survived for up to 20 weeks, and many of these cells eventually developed neurite-like processes. Continued uncontrolled tumor growth was not observed.
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PMID:Properties of PC12 pheochromocytoma cells transplanted to the adult rat brain. 287 97

Two neurotransmitter-synthesizing enzymes, tyrosine hydroxylase (TH) and choline acetyltransferase (CAT), were assayed in neuroblastoma tissues from 24 children, in human neuroblastoma tissues serially transplanted in nude mice, and in human neuroblastoma cells in culture. Among tissues from 24 children, five showed an adrenergic pattern with significant TH activity alone, seven showed a cholinergic pattern with significant CAT activity alone, and the remaining 12 specimens showed a "both-active" pattern with both TH and CAT activity. Enzymatic activities were maintained through many serial passages in vitro and in nude mice. All four specimens from children under one year of age exhibited the adrenergic pattern. In general, enzymatic activity was not correlated with degree of differentiation histologically. Among four cases of paravertebral dumb-bell type in this series, two were cholinergic, one was adrenergic, and the last was both-active. These results suggest that dumb-bell type tumors may arise from either sympathetic ganglia or dorsal root ganglia. This study supports the concept that neuroblastomas are a composite of adrenergic and cholinergic cells. Significant changes in the relative proportions of these two cell types were observed with time, and after extensive therapy. Different metastatic sites often exhibited important differences in enzymatic activity. These results help to account for clinical discrepancies between urinary VMA levels and tumor growth. Assays for TH and CAT can be useful for confirming a diagnosis of neuroblastoma, and have important potential for helping to clarify the natural history of neuroblastoma.
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PMID:Tyrosine hydroxylase and choline acetyltransferase activity in human neuroblastoma. Correlations with clinical features. 613 77

We have examined the ability of a number of neuropeptides to increase tyrosine hydroxylase (TH) activity in the superior cervical ganglion in vitro. Secretin and vasoactive intestinal peptide (VIP) both increased TH activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, insulin, luteinizing hormone-releasing hormone, [D-Ala2, Met5]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin and VIP increased TH activity with an EC50 of 5 nM and 0.5 microM, respectively. The effects of these peptides were not altered by prior decentralization of the ganglia, by addition of hexamethonium (3 mM) and atropine (6 microM), or by lowering the concentration of calcium in the medium to 0.1 mM. Addition of carbachol (3 microM) potentiated the effects of both secretin and VIP on TH activity. Several gastrointestinal peptides with structural similarities to secretin and VIP were examined for their ability to increase TH activity. Glucagon, gastric inhibitory peptide and human pancreatic tumor growth hormone-releasing factor produced no effect at a concentration of 10 microM, while PHI increased enzyme activity.
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PMID:Acute stimulation of ganglionic tyrosine hydroxylase activity by secretin, VIP and PHI. 614 16

We have earlier reported that dopamine (DA) activity in the preoptic anterior hypothalamic (POA-AH) region of castrated rats is inhibited by testosterone and accelerated by PRL. These results suggested that dopaminergic neurons may play an important role in male copulatory behavior, particularly in the attenuation of sex behavior reported to be associated with hyperprolactinemia. We have now examined the effects of severe hyperprolactinemia on the POA-AH DA activity in association with any modifications of copulatory behavior. Sexually experienced adult male rats were castrated and implanted sc with Silastic implants containing testosterone to maintain serum testosterone levels in the range found in intact rats. Hyperprolactinemia was induced by inoculation of minced MtTW15 PRL secreting pituitary tumor fragments. Copulatory behavior was assessed at weekly intervals in hyperprolactinemic and control rats. During the period of tumor growth serum PRL levels increased logarithmically. Whereas sexual activity continued to improve in control rats, there was a marked decrease in several important parameters of copulatory behavior in hyperprolactinemic rats. The most dramatic decrease occurred in the percentage of tumor-bearing rats ejaculating which decreased progressively to zero at 6 weeks after tumor inoculation. Ejaculation frequency decreased and ejaculation latency increased in tumor-bearing rats before the complete disappearance of ejaculatory behavior. The deficits in copulatory behavior of hyperprolactinemic rats were accompanied in parallel studies by significant depletions of DA concentrations in the POA-AH. Further, neuronal activity, as evidenced by the turnover rates measured by rate of loss of DA after tyrosine hydroxylase inhibition with alpha-methyl paratyrosine, was markedly augmented in the POA-AH of hyperprolactinemic rats as compared to control animals. These findings disclose a close association between the acceleration in POA-AH DA activity and the attenuation of copulatory behavior induced by hyperprolactinemia and suggest the probability of an underlying role of the POA-AH DA neurons in male sex behavior normally induced by testosterone.
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PMID:Effects on male sex behavior and preoptic dopamine neurons of hyperprolactinemia induced by MtTW15 pituitary tumors. 664 26

Chronic exposure of F344 rats to diethylstilbestrol (DES) induces pituitary tumors (DES-T) composed of proliferating lactotrophs. Presently, we studied the effect of progestins on parameters related to tumor growth and function, due to previous evidences of progesterone antagonism of pituitary tumorigenesis acting at pituitary and hypothalamic levels [Piroli, G., Grillo, C., Ferrini, M., Lux-Lantos, V. and De Nicola, A. F., Antagonism by progesterone of diethylstilbestrol-induced pituitary tumorigenesis in Fischer 344 rats: Effects on sex steroid receptors and tyrosine hydroxylase mRNA, Neuroendocrinology, 1996, 63, 530-539]. In search of a quantitatively more important effect, animals bearing DES-T were treated with synthetic progestins. Competition assays using DES-T as source of progestin receptors indicated that levonorgestrel (LNG), gestodene and R5020 showed higher affinities (IC50 1-2 nM) than progesterone, norethisterone and medroxyprogesterone (IC50 10-25 nM). Treatment with LNG reduced DES-T weight by 45%, and serum PRL by one half. Small (monomeric) and big (polymeric) PRL increased 5- and 2.5-fold, respectively, in DES-T in comparison with pituitaries of ovariectomized (OVX) rats. However, LNG produced no changes indicating that synthesis and storage of PRL was conserved in rats receiving both hormonal treatments. DES induced a 15-fold increase in cell proliferation, measured as bromodeoxyuridine incorporation into cell nuclei, in comparison to OVX rats, while LNG treatment of DES-T bearing rats reduced this index by 72%. Electron microscopic images showed that LNG markedly reduced hypertrophy and hyperplasia of lactotropes, increasing the proportions of degenerating cells and cells of high electronic density with alterations of cytoplasmic organelles. However, histopathological signs of apoptosis were absent. Therefore, reduced cell proliferation and non-apoptotic cell death are part of the mechanisms employed by progestins to antagonize tumorigenesis at the pituitary level. The results may open a new therapeutic strategy for treatment of PRL secreting adenoma in humans.
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PMID:Mechanisms in progestin antagonism of pituitary tumorigenesis. 956 11

Inhibition of angiogenesis has been shown to reduce tumor growth, metastasis, and tumor microvascular density in experimental models. To these effects we would now like to add induction of differentiation, based on biological analysis of xenografted human neuroblastoma (SH-SY5Y, WAG rnu/rnu) treated with the angiogenesis inhibitor TNP-470. Treatment with TNP-470 (10 mg/kg s.c., n = 15) reduced the tumor growth by 66% and stereological vascular parameters (Lv, Vv, Sv) by 36-45%. The tumor cell apoptotic fraction increased more than threefold, resulting in a decrease in viable tumor cells by 33%. In contrast, the mean vascular diameter (29 microm) and the mean tumor cell proliferative index (49%) were unaffected. TNP-470-treated tumors exhibited striking chromaffin differentiation of neuroblastoma cells, observed as increased expression of insulin-like growth factor II gene (+88%), tyrosine hydroxylase (+96%), chromogranin A, and cellular processes. Statistical analysis revealed an inverse correlation between differentiation and angiogenesis. It is suggested that by inhibiting angiogenesis, TNP-470 induces metabolic stress, resulting in chromaffin differentiation and apoptosis in neuroblastoma. Such agonal differentiation may be the link between angiostatic therapy and tumor cell apoptosis.
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PMID:Inhibition of angiogenesis induces chromaffin differentiation and apoptosis in neuroblastoma. 1002 98

Neuroblastoma is a malignant solid tumor of childhood with a poor prognosis. The growth of solid tumors has been shown to be dependent on new blood vessel formation, i.e. angiogenesis. Several steps in the metastatic process have also been found to be angiogenesis-dependent. Neuroblastomas grow quickly, are highly vascularized, and metastasize early, and hence inhibition of angiogenesis--angiostatic therapy--may be indicated in this disease. In order to investigate the effects of angiostatic agents in this disease, a new animal experimental model for human neuroblastoma was developed. Three angiostatic agents were tested in the model: TNP-470, the synthetic analogue of fumagillin, given subcutaneously, and the endogenous steroid 2-methoxyestradiol and its derivative 2-propynylestradiol, given orally. TNP-470 administration resulted in a significant reduction of the tumor growth rate and microvascular counts, and of the fraction of viable tumor cells, compared to controls. The fraction of apoptotic tumor cells increased threefold, while that of proliferative cells remained unaltered. This can explain the reduced net growth. Treatment with the angiostatic and chemotherapeutic steroids 2-methoxyestradiol and 2-propynylestradiol yielded similar results. However, the mechanism of action of these steroids was bimodal; the effect occurring both through inhibition of tumor angiogenesis and through induction of tumor cell apoptosis. It was shown for the first time that inhibition of angiogenesis regardless of agent induces striking chromaffin differentiation, observed as increased expression of insulin-like growth factor II gene, tyrosine hydroxylase, and chromogranin A, and increased formation of cellular processes. It is suggested that inhibition of angiogenesis induces metabolic stress, resulting in chromaffin differentiation and apoptosis. Such agonal differentiation may be the link between angiostatic therapy and tumor cell apoptosis. Angiostatic agents administered as single therapy have an objective tumoristatic effect in our neuroblastoma model. Angiostatic treatment of neuroblastoma is a new and promising treatment modality that merits clinical investigation.
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PMID:Angiostatic treatment of neuroblastoma. 1037 67

Hypoxia is an important pathophysiological stress that occurs during blood vessel injuries and tumor growth. It is now well documented that hypoxia leads to the activation of several transcription factors which participate in the adaptive response of the cells to hypoxia. Among these transcription factors, AP-1 is rapidly activated by hypoxia and triggers bFGF, VEGF, and tyrosine hydroxylase gene expression. However, the mechanisms of AP-1 activation by hypoxia are not well understood. In this report, we studied the events leading to AP-1 activation in hypoxia. We found that c-jun protein accumulates in hypoxic HepG2 cells. This overexpression is concomitant with c-jun phosphorylation and JNK activation. Moreover, we showed that AP-1 is transcriptionally active. We also observed that AP-1 transcriptional activity is inhibited by a MEKK1 dominant negative mutant. Moreover, the MEKK1 dominant negative mutant as well as deletion of the AP-1 binding sites within the c-jun promoter inhibited the c-jun promoter activation by hypoxia. All together, these results indicate that, in hypoxic HepG2 cells, AP-1 is activated through a JNK-dependent pathway and that it is involved in the regulation of the c-jun promoter, inducing a positive feedback loop on AP-1 activation via c-jun overexpression.
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PMID:c-JUN gene induction and AP-1 activity is regulated by a JNK-dependent pathway in hypoxic HepG2 cells. 1128 49

Alteration in ganglioside composition in F-11 cells by suppression of GD3-synthase gene expression resulted in greatly reduced tumor growth and metastasis when the cells were injected into nude mice. To identify genes whose expression is correlated with the decreased level of ganglioside GD3, we analyzed gene expression profiles of the GD3-suppressed F-11 cells and the control F-11 cells using DNA microarrays. We identified a set of GD3-related genes, most of which are involved in tumor growth and development. The genes that define the proliferation-transformation signature are down-regulated, such as creatine kinase-B (CKB), upstream stimulation factor 1 (USF-1), type II cAMP-dependent protein kinase regulatory subunit (RII PKA), and tyrosine hydroxylase (TH). On the other hand, the genes that define the differentiation-reverse transformation signature are up-regulated, including p160 myb-binding protein (P160), brain factor-2, insulin-like growth factor-binding protein (IGFBP), and growth/differentiation factor 11. Transcriptional levels of the genes that showed the most distinct GD3-related expression change were validated by reverse transcription-polymerase chain reaction (RT-PCR). Defining GD3-related genes may lead to identification of clinically relevant therapeutics and to understanding of the mechanism(s) by which ganglioside GD3 affects tumor growth and metastasis.
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PMID:Variations in gene expression patterns correlated with phenotype of F-11 tumor cells whose expression of GD3-synthase is suppressed. 1184 46


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