Effects of Fasting on the Expression of Gastrin, Cholecystokinin, and Somatostatin Genes and of Various Housekeeping Genes in the Pancreas and Upper Digestive Tract of Rats

Yamada, Hironori; Chen, Duan; Monstein, Hans‐Jürg; Håkanson, R.

doi:10.1006/bbrc.1997.6198

Cited by 85 publications

(43 citation statements)

References 15 publications

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“…gapdh is frequently used for this purpose because of the widely accepted assumption that the transcriptional levels of this gene are not affected by different treatments regimes. This assumption has been recently challenged 48 and indeed, our experiments demonstrate that paclitaxel changes gapdh gene expression in some tumors. In fact, bax expression showed less fluctuation than gapdh expression.…”

Section: Discussionmentioning

confidence: 66%

Development and validation of sensitive assays to quantitate gene expression after p53 gene therapy and paclitaxel chemotherapy using in vivo dosing in tumor xenograft models

Wen¹,

Xie²,

McDonald³

et al. 2000

Cancer Gene Ther

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SCH58500 ( ACN53 ) is a replication -deficient, type 5 adenovirus ( Ad ) expressing human wild -type p53 tumor suppressor. It is currently undergoing clinical trials as a cancer therapeutic. Many SCH58500 clinical trials incorporate an arm comparing traditional chemotherapy against chemotherapy combined with SCH58500. Paclitaxel was chosen for combination therapy in the preclinical study reported here due to its extensive use as a first -line therapy in ovarian cancer, its synergy with SCH58500 in preclinical cancer models, and its activation of p53 -independent apoptosis, which might result in a``lowered threshold'' for tumor cell death. SCID mice bearing human tumor xenografts were dosed with intratumoral vehicle, control Ad vector, or SCH58500, with or without paclitaxel. Real -time quantitative reverse transcriptase polymerase chain reaction assays were developed and validated to quantitate expression of p53, the p53 downstream effector gene p21, and the apoptosis -related genes, bax, bcl -2, and survivin. Protein expression was confirmed using immunohistochemical assays for p53 and p21. Only tumors injected with SCH58500 had detectable levels of exogenous p53 DNA and mRNA. After SCH58500 treatment, 3 ± 11 ± fold elevations of p21 expression were observed in tumor xenografts containing nonfunctional p53 ( MDA -MB -468, MDA -MB -231, MIAPaCa2, DU -145, and SK -OV -3 ) , but no change in p21 mRNA in wild -type p53 PA -1 tumors. Immunohistochemical assays confirmed induction of p21 protein in MDA -MB -468 and SK -OV -3 cells, but not in PA -1 cells. Ad vector alone or paclitaxel alone had no effect on p21 mRNA levels in most tumors. However, paclitaxel suppressed p21 expression induced by SCH58500 4 -fold in DU -145 and SK -OV -3 tumors. Paclitaxel also affected expression of the housekeeping gene gapdh. There was no consistent pattern to the changes in bax, bcl -2, or survivin after SCH58500 treatment with or without paclitaxel between tumor types, although there were consistent responses within individual tumor lines. The mRNA ratios for bax / bcl -2 and bax / survivin were also not informative across tumor types. Of the genes examined, only p21 gave a predictable response 24 hours after p53 gene therapy and therefore, p21 expression may be useful for confirming SCH58500 activity in human tumor biopsies.

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Section: Discussionmentioning

confidence: 66%

Development and validation of sensitive assays to quantitate gene expression after p53 gene therapy and paclitaxel chemotherapy using in vivo dosing in tumor xenograft models

Wen¹,

Xie²,

McDonald³

et al. 2000

Cancer Gene Ther

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“…A modest inhibitory effect of fasting on hypothalamic SST expression has been previously reported in mice (35). However, in the rat, fasting has been reported to enhance SST mRNA levels in the pyloric antrum but not the acid-secreting region of the stomach (38,48), although others report a regional increase or decrease in SST mRNA following fasting, depending on the housekeeping gene used as the internal control (49). HPA axis of Sst ϩ/ϩ vs. Sst Ϫ/Ϫ mice.…”

Section: Somatostatinmentioning

confidence: 89%

Evidence that endogenous SST inhibits ACTH and ghrelin expression by independent pathways

Luque

Gahete²,

Hochgeschwender³

et al. 2006

American Journal of Physiology-Endocrinology and Metabolism

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Corticosterone and total ghrelin levels are increased in somatostatin (SST) knockout mice (Sst Ϫ/Ϫ ) compared with SST-intact controls (Sst ϩ/ϩ ). Because exogenous ghrelin can increase glucocorticoids, the question arises whether elevated levels of ghrelin contribute to elevated corticosterone levels in Sst Ϫ/Ϫ mice. We report that Sst Ϫ/Ϫ mice had elevated mRNA levels for pituitary proopiomelanocortin (POMC), the precursor of adrenocorticotropic hormone (ACTH), whereas mRNA levels for hypothalamic corticotropin-releasing hormone (CRH) did not differ from Sst ϩ/ϩ mice. Furthermore, SST suppressed pituitary POMC mRNA levels and ACTH release in vitro independently of CRH actions. In contrast, it has been reported that ghrelin increases glucocorticoids via a central effect on CRH secretion and that n-octanoyl ghrelin is the form of ghrelin that activates the GHS-R1a and modulates CRH neuronal activity. Consistent with elevations in total ghrelin levels, Sst Ϫ/Ϫ mice displayed an increase in stomach ghrelin mRNA levels, whereas hypothalamic and pituitary expression of ghrelin was not altered. Despite the increase in total ghrelin levels, circulating levels of n-octanoyl ghrelin were not altered in Sst Ϫ/Ϫ mice. Because glucocorticoids and ghrelin increase in response to fasting, we examined the impact of fasting on the adrenal axis and ghrelin in Sst ϩ/ϩ and Sst Ϫ/Ϫ mice and found that endogenous SST does not significantly contribute to this adaptive response. We conclude that endogenous SST inhibits basal ghrelin gene expression in a tissue specific manner and independently and directly inhibits pituitary ACTH synthesis and release. Thus endogenous SST exerts an inhibitory effect on ghrelin synthesis and on the adrenal axis through independent pathways. somatostatin; adrenocorticotropic hormone; hypothalamic-pituitaryadrenal axis; corticotropin-releasing hormone; pituitary; stomach SOMATOSTATIN (SST), OR ITS SYNTHETIC ANALOGS, can reduce circulating adrenocorticotropic hormone (ACTH) and glucocorticoid levels in rats and humans in vivo (19,43,46). The inhibitory actions of SST are believed to be due, at least in part, to a direct effect on the pituitary. This hypothesis is supported by the fact that SST can block corticotropin-releasing hormone (CRH)-mediated ACTH release in cultures of primary rat pituitary cells, mouse pituitary tumor cells (AtT-20), and cultures of human corticotropinomas (20,25,44), where this effect appears to be mediated by the SST receptors sst2 and/or sst5 (20,43,44). Both the in vivo and in vitro inhibitory effects of SST on ACTH release can be masked by glucocorticoids, where glucocorticoids directly inhibit basal and CRH-mediated ACTH release (19,25). However, a recent study (20) demonstrates that an sst5 selective agonist can inhibit ACTH release in vitro in the presence of glucocorticoids. The inhibitory action of exogenous SST on ACTH release has prompted speculation regarding the role of endogenous SST as a corticotropin release-inhibiting factor (14). More recent observations suppo...

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“…GAPDH expression is substantially increased in human cancers including breast [Revillion et al, 2000], pancreatic [Schek et al, 1988], lung [Sirover, 1997], and cervical [Kim et al, 1998]. Both GAPDH and beta-actin mRNA are down-regulated up to 50% in various regions of the rat digestive tract as a consequence of fasting [Yamada et al, 1997], while GAPDH mRNA levels are increased in rat aorta about 2.5-fold as a result of oxidative stress [Ito et al, 1996]. GAPDH mRNA is up-regulated in the endometrium, but down-regulated in the liver by estradiol in ewes [Zou and Ing, 1998].…”

Section: Discussionmentioning

confidence: 99%

Muscarinic receptor transcript and protein density in hypertrophied and atrophied rat urinary bladder

Braverman

Ruggieri

2005

Neurourology and Urodynamics

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Aims-Our previous studies showed that bladder hypertrophy shifts the muscarinic receptor subtype mediating contraction from M 3 towards M 2 along with increased M 2 and decreased M 3 protein concentration. We quantified mRNA for M 1 through M 5 receptors to determine whether the changes in M 2 and M 3 protein levels was due to changes in transcription.Methods-Bladder hypertrophy was induced by bladder outlet obstruction (BOO), major pelvic ganglion electrocautery (DEN), and major pelvic ganglion decentralization (DEC). Bladder atrophy was induced by ureteral diversion (DIV). Additional groups included denervated and diverted (DEN-DIV), sham operated (SHAM), and normal (NOR) controls. Transcripts were quantified using a multiplex ribonuclease protection assay (RPA) and receptor protein density was determined by immunoprecipitation. Receptor transcripts were expressed per unit total RNA.Results-Although all five receptor subtype transcripts were detected in all experimental groups, the densities of M 1 , M 4 , and M 5 were much lower than for the M 2 and M 3 subtype. There were more M 2 receptor transcripts than all the others, consistent with M 2 protein determinations. M 2 transcripts were significantly increased in DEN and BOO bladders. Surprisingly, M 3 transcripts were also significantly increased in BOO. There was a significant correlation (r = 0.98, P < 0.001) between protein density and transcript density for the M 2 but not the M 3 receptor among the different experimental groups.Conclusions-Changes in mRNA concentration are reflected by changes in protein density for the M 2 receptor but not for the M 3 receptor. Extrapolation of functional effects from transcript density data is invalid for M 3 mediated bladder contractions.

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Effects of Fasting on the Expression of Gastrin, Cholecystokinin, and Somatostatin Genes and of Various Housekeeping Genes in the Pancreas and Upper Digestive Tract of Rats

Cited by 85 publications

References 15 publications

Development and validation of sensitive assays to quantitate gene expression after p53 gene therapy and paclitaxel chemotherapy using in vivo dosing in tumor xenograft models

Development and validation of sensitive assays to quantitate gene expression after p53 gene therapy and paclitaxel chemotherapy using in vivo dosing in tumor xenograft models

Evidence that endogenous SST inhibits ACTH and ghrelin expression by independent pathways

Muscarinic receptor transcript and protein density in hypertrophied and atrophied rat urinary bladder

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