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Tamoxifen suppresses pancreatic ?-cell proliferation in mice.

ABSTRACT: Tamoxifen is a mixed agonist/antagonist estrogen analogue that is frequently used to induce conditional gene deletion in mice using Cre-loxP mediated gene recombination. Tamoxifen is routinely employed in extremely high-doses relative to typical human doses to induce efficient gene deletion in mice. Although tamoxifen has been widely assumed to have no influence upon ?-cells, the acute developmental and functional consequences of high-dose tamoxifen upon glucose homeostasis and adult ?-cells are largely unknown. We tested if tamoxifen influences glucose homeostasis in male mice of various genetic backgrounds. We then carried out detailed histomorphometry studies of mouse pancreata. We also performed gene expression studies with islets of tamoxifen-treated mice and controls. Tamoxifen had modest effects upon glucose homeostasis of mixed genetic background (F1 B6129SF1/J) mice, with fasting hyperglycemia and improved glucose tolerance but without overt effects on fed glucose levels or insulin sensitivity. Tamoxifen inhibited proliferation of ?-cells in a dose-dependent manner, with dramatic reductions in ?-cell turnover at the highest dose (decreased by 66%). In sharp contrast, tamoxifen did not reduce proliferation of pancreatic acinar cells. ?-cell proliferation was unchanged by tamoxifen in 129S2 mice but was reduced in C57Bl6 genetic background mice (decreased by 59%). Gene expression studies revealed suppression of RNA for cyclins D1 and D2 within islets of tamoxifen-treated mice. Tamoxifen has a cytostatic effect on ?-cells, independent of changes in glucose homeostasis, in mixed genetic background and also in C57Bl6 mice. Tamoxifen should be used judiciously to inducibly inactivate genes in studies of glucose homeostasis.

SUBMITTER: Ahn SH

PROVIDER: S-EPMC6731016 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Tamoxifen suppresses pancreatic β-cell proliferation in mice.

Ahn Surl-Hee SH Granger Anne A Rankin Matthew M MM Lam Carol J CJ Cox Aaron R AR Kushner Jake A JA

PloS one 20190906 9

Tamoxifen is a mixed agonist/antagonist estrogen analogue that is frequently used to induce conditional gene deletion in mice using Cre-loxP mediated gene recombination. Tamoxifen is routinely employed in extremely high-doses relative to typical human doses to induce efficient gene deletion in mice. Although tamoxifen has been widely assumed to have no influence upon β-cells, the acute developmental and functional consequences of high-dose tamoxifen upon glucose homeostasis and adult β-cells are ...[more]

PMID: 31490929

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Project description:BackgroundPancreatic cancer (PC) is one of the most lethal solid malignancies in the world due to its excessive cell proliferation and aggressive metastatic features. Emerging evidences revealed the importance of posttranscriptional modifications of RNAs in PC progression. However, knowledge about the 5-methylcytosine (m5C) RNA modification in PC is still extremely limited. In this study, we attempted to explore the expression changes and clinical significances of 12 known m5C-related genes among PC patients.MethodsA total of 362 normal and 382 tumor specimens from PC patients were examined for candidate m5C-related gene and protein expression by using quantitative PCR (qPCR) and immunohistochemistry (IHC). The proliferation rate of PC cells was detected by MTS assay. Xenograft mouse models were used to assess the role of NSUN6 in PC tumor formation.FindingsThrough analyzing the four Gene Expression Omnibus (GEO) databases, six m5C-related genes shown significant and consistent alterations were selected for further examination in our 3 independent PC cohorts. Finally, we identified the reduction of NSUN6 as a common feature of all PC sample sets examined. NSUN6 expression correlated with clinicopathologic parameters including T stage, and Ki67+ cell rate. Further assessing the transcriptional profiles of 50 PC tissues, we found biological processes associated with cell proliferation like cell cycle and G2M checkpoint were enriched in NSUN6 lower expression group. Helped by in vitro PC cell lines and in vivo xenograft mouse models, we confirmed the role of NSUN6 in regulating cell proliferation and PC tumor growth. Last but also importantly, we also show the good performance of NSUN6 in evaluating tumor recurrence and survival among PC patients.InterpretationOur data suggested that NSUN6 is an important factor involved in regulating cell proliferation of PC, and highlights the potential of novel m5C-based clinical modalities as a therapeutic approach in PC patients.FundingThis study was supported by the National Natural Science Foundation of China (Grant Nos. 81803014, 81802424, and 81802911).

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Tamoxifen suppresses pancreatic ?-cell proliferation in mice.

Publications

Tamoxifen suppresses pancreatic β-cell proliferation in mice.

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