Dataset Information

GH/STAT5 signaling during the growth period in livers of mice overexpressing GH.

ABSTRACT: GH/STAT5 signaling is desensitized in the liver in adult transgenic mice overexpressing GH; however, these animals present greater body size. To assess whether the STAT5 pathway is active during the growth period in the liver in these animals, and how signaling modulators participate in this process, growing transgenic mice and normal siblings were evaluated. STAT5 does not respond to an acute GH-stimulus, but displays higher basal phosphorylation in the livers of growing GH-overexpressing mice. GH receptor and the positive modulators glucocorticoid receptor and HNF1 display greater abundance in transgenic animals, supporting the activity of STAT5. The negative modulators cytokine-induced suppressor and PTP1B are increased in GH-overexpressing mice. The suppressors SOCS2 and SOCS3 exhibit higher mRNA levels in transgenic mice but lower protein content, indicating that they are being actively degraded. Therefore, STAT5 signaling is increased in the liver in GH-transgenic mice during the growth period, with a balance between positive and negative effectors resulting in accelerated but controlled growth.

SUBMITTER: Martinez CS

PROVIDER: S-EPMC4811361 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

GH/STAT5 signaling during the growth period in livers of mice overexpressing GH.

Martinez Carolina S CS Piazza Verónica G VG Díaz María E ME Boparai Ravneet K RK Arum Oge O Ramírez María C MC González Lorena L Becú-Villalobos Damasia D Bartke Andrzej A Turyn Daniel D Miquet Johanna G JG Sotelo Ana I AI

Journal of molecular endocrinology 20150217 2

GH/STAT5 signaling is desensitized in the liver in adult transgenic mice overexpressing GH; however, these animals present greater body size. To assess whether the STAT5 pathway is active during the growth period in the liver in these animals, and how signaling modulators participate in this process, growing transgenic mice and normal siblings were evaluated. STAT5 does not respond to an acute GH-stimulus, but displays higher basal phosphorylation in the livers of growing GH-overexpressing mice. ...[more]

PMID: 25691498

Similar Datasets

Project description:Background & aimsThe ratio of liver size to body weight (hepatostat) is tightly controlled, but little is known about how the physiologic functions of the liver help determine its size. Livers of mice repopulated with human hepatocytes (humanized livers) grow to larger than normal; the human hepatocytes do not recognize the fibroblast growth factor (FGF)-15 produced by mouse intestine. This results in up-regulation of bile acid synthesis in the human hepatocytes and enlargement of the bile acid pool. We investigated whether abnormal bile acid signaling affects the hepatostat in mice.MethodsWe crossed Fah(-/-), Rag2(-/-), Il2r(-/-) mice with nonobese diabetic mice to create FRGN mice, whose livers can be fully repopulated with human hepatocytes. We inserted the gene for human FGF19 (ortholog to mouse Fgf15), including regulatory sequences, into the FRGN mice to create FRGN19(+) mice. Livers of FRGN19(+) mice and their FRGN littermates were fully repopulated with human hepatocytes. Liver tissues were collected and bile acid pool sizes and RNA sequences were analyzed and compared with those of mice without humanized livers (controls).ResultsLivers were larger in FRGN mice with humanized livers (13% of body weight), compared with control FRGN mice; they also had much larger bile acid pools and aberrant bile acid signaling. Livers from FRGN19(+) normalized to 7.8% of body weight, and their bile acid pool and signaling more closely resembled that of control FRGN19(+) mice. RNA sequence analysis showed activation of the Hippo pathway, and immunohistochemical and transcription analyses revealed increased hepatocyte proliferation, but not apoptosis, in the enlarged humanized livers of FRGN mice. Cell sorting experiments showed that although healthy human liver does not produce FGF19, nonparenchymal cells from cholestatic livers produce FGF19.ConclusionsIn mice with humanized livers, expression of an FGF19 transgene corrects bile acid signaling defects, resulting in normalization of bile acid synthesis, the bile acid pool, and liver size. These findings indicate that liver size is, in part, regulated by the size of the bile acid pool that the liver must circulate.

Project description:Growth hormone (GH) facilitates therapy resistance in the cancers of breast, colon, endometrium, and melanoma. The GH-stimulated pathways responsible for this resistance were identified as suppression of apoptosis, induction of epithelial-to-mesenchymal transition (EMT), and upregulated drug efflux by increased expression of ATP-binding cassette containing multidrug efflux pumps (ABC-transporters). In extremely drug-resistant melanoma, ABC-transporters have also been reported to mediate drug sequestration in intracellular melanosomes, thereby reducing drug efficacy. Melanocyte-inducing transcription factor (MITF) is the master regulator of melanocyte and melanoma cell fate as well as the melanosomal machinery. MITF targets such as the oncogene MET, as well as MITF-mediated processes such as resistance to radiation therapy, are both known to be upregulated by GH. Therefore, we chose to query the direct effects of GH on MITF expression and activity towards conferring chemoresistance in melanoma. Here, we demonstrate that GH significantly upregulates MITF as well as the MITF target genes following treatment with multiple anticancer drug treatments such as chemotherapy, BRAF-inhibitors, as well as tyrosine-kinase inhibitors. GH action also upregulated MITF-regulated processes such as melanogenesis and tyrosinase activity. Significant elevation in MITF and MITF target gene expression was also observed in mouse B16F10 melanoma cells and xenografts in bovine GH transgenic (bGH) mice compared to wild-type littermates. Through pathway inhibitor analysis we identified that both the JAK2-STAT5 and SRC activities were critical for the observed effects. Additionally, a retrospective analysis of gene expression data from GTEx, NCI60, CCLE, and TCGA databases corroborated our observed correlation of MITF function and GH action. Therefore, we present in vitro, in vivo, and in silico evidence which strongly implicates the GH-GHR axis in inducing chemoresistance in human melanoma by driving MITF-regulated and ABC-transporter-mediated drug clearance pathways.

Project description:Osteosarcoma (OS) is the most common primary bone tumor that primarily affects children and adolescents. Studies suggested that dysregulation JAK/STAT signaling promotes the development of OS. Cells treated with pimozide, a STAT5 inhibitor suppressed proliferation and colony formation and induced sub G0/G1 cell cycle arrest and apoptosis. There was a reduction in cyclin D1 and CDK2 expression and Rb phosphorylation, and activation of Caspase-3 and PARP cleavage. In addition, pimozide suppressed the formation of 3-dimensional osteospheres and growth of the cells in the Tumor in a Dish lung organoid system. Furthermore, there was a reduction in expression of cancer stem cell marker proteins DCLK1, CD44, CD133, Oct-4, and ABCG2. More importantly, it was the short form of DCLK1 that was upregulated in osteospheres, which was suppressed in response to pimozide. We further confirmed by flow cytometry a reduction in DCLK1+ cells. Moreover, pimozide inhibits the phosphorylation of STAT5, STAT3, and ERK in OS cells. Molecular docking studies suggest that pimozide interacts with STAT5A and STAT5B with binding energies of -8.4 and -6.4?Kcal/mol, respectively. Binding was confirmed by cellular thermal shift assay. To further understand the role of STAT5, we knocked down the two isoforms using specific siRNAs. While knockdown of the proteins did not affect the cells, knockdown of STAT5B reduced pimozide-induced necrosis and further enhanced late apoptosis. To determine the effect of pimozide on tumor growth in vivo, we administered pimozide intraperitoneally at a dose of 10?mg/kg BW every day for 21 days in mice carrying KHOS/NP tumor xenografts. Pimozide treatment significantly suppressed xenograft growth. Western blot and immunohistochemistry analyses also demonstrated significant inhibition of stem cell marker proteins. Together, these data suggest that pimozide treatment suppresses OS growth by targeting both proliferating cells and stem cells at least in part by inhibiting the STAT5 signaling pathway.

Dataset Information

GH/STAT5 signaling during the growth period in livers of mice overexpressing GH.

Publications

GH/STAT5 signaling during the growth period in livers of mice overexpressing GH.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets