Growth Hormone Receptor and IGF-I Deficiency is Associated with Resistance to DNA Damage and Very Low Cancer and Diabetes Incidence in Humans
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ABSTRACT: Growth Hormone Receptor Deficiency (GHRD) in mice causes life span extension and a major increase in the portion of animals that die without detectable pathologies including cancer and insulin resistance. During a 22-year monitoring of a cohort of 0-88 year old Ecuadorian GHRD subjects with severe IGF-I deficiency developed we observed a single, non-lethal malignancy and no diabetes. To understand the mechanisms responsible for this low disease incidence we incubated Human Mammary Epithelial Cells (HMECs) with serum from either GHRD or control subjects. GHRD serum not only protected mammary cells against hydrogen peroxide-dependent DNA damage but also promoted cell death in severely damaged cells by a mechanism blocked by IGF-I. The gene expression or DNA damage profile in epithelial cells exposed to GHRD serum, fibroblasts lacking the IGF-I receptor, and long-lived yeast lacking homologs of IGF-I signaling genes point to stress resistance transcription factors and SOD2 as mediators of GHRD-associated protection. These results provide evidence for a role of GH and IGF-I deficiency in promoting healthy aging in humans. Primary Human Mammalian Epithelial Cells (HMECs), were cultured in HMEC medium (ScienCell) at 37oC and 5% CO2 in Poly-L-Lysine coated culture dishes (Sigma). Treatment consisted of cells being stimulated with HMEC basal medium containing either 15% GHRD serum or 15% control serum for 6 hours. Cells were then harvested and processed for RNA extraction.
Project description:Molecular distinctions between the stasis and telomere attrition senescence barriers in cultured human mammary epithelial cells Normal human epithelial cells in culture have generally shown a limited proliferative potential of ~10-40 population doublings before encountering a stress-associated senescence barrier (stasis) associated with elevated levels of cyclin-dependent kinase inhibitors p16 and/or p21. We now show that simple changes in media composition can expand the proliferative potential of human mammary epithelial cells (HMEC) initiated as primary cultures to 50-60 population doublings, followed by p16(+), senescence-associated b-galactosidase(+) stasis. We compared the properties of growing and senescent pre-stasis HMEC with growing and senescent post-selection HMEC, i.e., cells grown in a serum-free medium that overcame stasis via silencing of p16 expression and that display senescence associated with telomere dysfunction. Cultured pre-stasis populations contained cells expressing markers associated with luminal and myoepithelial HMEC lineages in vivo, in contrast to the basal-like phenotype of the post-selection HMEC. Gene transcript and protein expression, DNA damage-associated markers, mean TRF length, and genomic stability, differed significantly between HMEC populations at the stasis vs. telomere attrition senescence barriers. Senescent isogenic fibroblasts showed greater similarity to HMEC at stasis than at telomere attrition, although their gene transcript profile was distinct from HMEC at both senescence barriers. These studies support our model of the senescence barriers encountered by cultured HMEC in which the first barrier, stasis, is Rb-mediated and independent of telomere length, while a second barrier (agonescence or crisis) results from telomere attrition leading to telomere dysfunction. Additionally, the ability to maintain long-term growth of genomically stable multi-lineage pre-stasis HMEC populations can greatly enhance experimentation with normal HMEC. 48 samples from Human Mammary Epithelial cells which includes samples from four different individuals at different passage levels which includes prestasis,intermediate,post selection and agonesence stages of cell cycle.
Project description:Several studies have shown that bone mineral density (BMD), a clinically measurable predictor of osteoporotic fracture, is the sum of genetic and environmental influences. In addition, serum IGF-1 levels have been correlated to both BMD and fracture risk. We previously identified a Quantitative Trait Locus (QTL) for Bone Mineral Density (BMD) on mouse Chromosome (Chr) 6 that overlaps a QTL for serum IGF-1. The B6.C3H-6T (6T) congenic mouse is homozygous for C57BL/6J (B6) alleles across the genome except for a 30 cM region on Chr 6 that is homozygous for C3H/HeJ (C3H) alleles. This mouse was created to study biology behind both the BMD and the serum IGF-1 QTLs and to identify the gene(s) underlying these QTLs. Female 6T mice have lower BMD and lower serum IGF-1 levels at all ages measured. As the liver is the major source of serum IGF-1, we examined differential expression in the livers of fasted female B6 and 6T mice by microarray. Experiment Overall Design: The experimental design of this experiment was a simple two-factor experiment, with three biological replicates of each factor (in this case mouse strain, B6.C3H-6T vs. C57BL/6J).
Project description:Dysregulation of the epigenome is a common event in malignancy. However, deciphering the earliest cancer associated epigenetic events remains a challenge. Cancer epigenome studies to date have primarily utilised cancer cell lines or clinical samples, where it is difficult to identify the initial epigenetic lesions from those that occur over time. Here, we analysed the epigenome of normal Human Mammary Epithelial Cells (HMEC) and a matched variant cell population (vHMEC) that has escaped senescence and undergone partial carcinogenic transformation. Using this model system we sought to identify the earliest epigenetic changes that potentially occur during carcinogenesis. First we show that the transcriptome of vHMEC resembles that of basal-like breast cancer. Moreover, in vHMEC there is significant deregulation of MYC, p53, EZH2/polycomb, the Aryl Hydrocarbon Receptor (AHR) and miRNAs-143, 145, 199a and 519a at the transcriptional level. Second, we find that vHMEC exhibit genome-wide changes in DNA methylation affecting key cancer-associated pathways. Hypermethylation predominately impacted gene promoters (particularly those targeted by AHR and TP53) and polycomb associated loci, whereas hypomethylation frequently affected enhancers. Next we show that long range epigenetic deregulation occurred in vHMEC involving concordant change in chromatin modification and gene expression across ~0.5-1Mb regions. Finally, we demonstrate that the DNA methylation changes we observe in vHMECs, occur in basal-like breast cancer (notably FOXA1 hypermethylation).. Overall our results suggest that the first steps of carcinogenesis are associated with a co-ordinated deregulation of DNA methylation and chromatin modification spanning a range of genomic loci potentially targeted by key transcription factors and a corresponding deregulation of transcriptional networks. H3K27me3 ChIP-chip was performed on HMEC and vHMEC from 4 donors, H3K9ac was performed on cells from 2 donors. Both H3K27me3 and H3K9ac ChIP was performed on two time points for vHMEC and used the same input materia.
Project description:We report ChIP-Seq analysis of the RNA polyemerase I trascription factor UBF1/2 in NIH3T3, HMEC and HMLER cell lines. NIH3T3* samples: We correlated UBF1/2 binding across the genome with that of RNA polemerase I (Pol I), RNA polemerase II (Pol II) and chromatin states in NIH3T3 cells We perfromed ChIP-seq of UBF1/2 (2 biological replicates), Pol I (POLR1A/RPA194), Pol II, H3K9me3, H3K4Me3, H3K9ac, H4 hyperacetylation and genomic DNA input as reference. HMEC* samples: We report ChIP-Seq analysis of UBF1/2 and Pol I (POLR1A/RPA194) in human mammary epithelial cells (HMEC). In addition we include UBF1/2 ChIP-seq in the tumourigenic epithelial cell line HMLER. In this study, we compared UBF1/2 binding in HMEC to UBF1/2 binding in in the tumorigenic HMLER cells, an isogenic HMEC-derived cell line expressing the SV40 large-T, TERT, and an oncogenic allele of the HRAS gene (expressing HRASV12G) that forms tumors in nude mice (Elenbaas et al., Gene & Development 2001) We sequenced UBF1/2 ChIP and Pol I(POLR1A/RPA194) ChIP and gDNA input from HMEC. We sequenced UBF1/2 ChIP and gDNA input from HMLER
Project description:Cytoplasmic localization of proline, glutamic acid, leucine-rich protein 1 (PELP1) is observed in ∼40% of women with invasive breast cancer. In mouse models, PELP1 overexpression in the mammary gland leads to premalignant lesions and eventually mammary tumors. In preliminary clinical studies, cytoplasmic localization of PELP1 was seen in 36% of women at high risk of developing breast cancer. Here, we investigated whether cytoplasmic PELP1 signaling promotes breast cancer initiation in models of immortalized human mammary epithelial cells (HMECs). Global gene expression analysis was performed on HMEC lines expressing vector control, PELP1-wt, or mutant PELP1 in which the nuclear localization sequence was altered, resulting in cytoplasmic localization of PELP1 (PELP1-cyto). Global gene expression analysis identified that PELP1-cyto expression in HMECs induced NF-κB signaling pathways. Western blotting analysis of PELP1-cyto HMECs showed up-regulation of inhibitor of κB kinase ϵ (IKKϵ) and increased phosphorylation of the NF-κB subunit RelB. To determine whether secreted factors produced by PELP1-cyto HMECs promote macrophage activation, THP-1 macrophages were treated with HMEC-conditioned medium (CM). PELP1-cyto CM induced changes in THP-1 gene expression as compared with control cell CM. Double conditioned medium (DCM) from the activated THP-1 cells was then applied to HMECs to determine whether paracrine signaling from PELP1-cyto-activated macrophages could in turn promote migration of HMECs. PELP1-cyto DCM induced robust HMEC migration, which was reduced in DCM from PELP1-cyto HMECs expressing IKKϵ shRNA. Our findings suggest that cytoplasmic localization of PELP1 up-regulates pro-tumorigenic IKKϵ and secreted inflammatory signals, which through paracrine macrophage activation regulates the migratory phenotype associated with breast cancer initiation.
Project description:HMEC cultures were left untreated or stimulated for 5h with 2 ng/ml TNF. Comparison of the gene expression profiles revealed the TNF-mediated gene expression changes.
Project description:This SuperSeries is composed of the following subset Series: GSE25035: The role of p53 in the regulation of miRNA expression profiling GSE25036: miRNA expression profiling in human mammary epithelial cell (HMEC) CD24-CD44+ and non-CD24-CD44+ cell populations Refer to individual Series
Project description:Signalling between endothelial cells, endothelial progenitor cells and stromal cells is crucial for the establishment and maintenance of vascular integrity and involves exosomes, among other signalling pathways. Exosomes are important mediators of intercellular communication in immune signalling, tumour survival, stress responses and angiogenesis. The ability of exosomes to incorporate and transfer mRNAs encoding for ‘acquired’ proteins or miRNAs repressing ‘resident’ mRNA translation suggests that they can influence the physiological behaviour of recipient cells. We here demonstrate that miR-214, a miRNA that controls endothelial cell function and angiogenesis, plays a dominant role in exosome-mediated signalling between endothelial cells. Endothelial cell-derived exosomes stimulated migration and angiogenesis in recipient cells, whereas exosomes from miR-214 depleted endothelial cells failed to stimulate these processes. Exosomes containing miR-214 repressed the expression of Ataxia Telangiectasia Mutated in recipient cells, thereby preventing senescence and allowing blood vessel formation. Concordantly, specific reduction of miR-214 content in exosome-producing endothelial cells abolishes the angiogenesis the angiogenesis stimulatory function of the resulting exosomes. Collectively our data indicate that endothelial cells release miR-214 containing exosomes to stimulate angiogenesis through silencing of Ataxia Telangiectasia Mutated in neighbouring target cells. Gene expression analysis of HMEC endothelial cells exposed to supernatant containing either HMEC derived exosomes (miR-214 high), HMEC derived exosomes depleted of miR-214 (miR-214 low) or containing no exosomes (no exosomes). Each sample was analysed in duplo.
Project description:Senescence is a permanent cell cycle arrest that occurs in response to cellular stress. Because senescent cells promote age-related disease, there has been considerable interest in defining the proteomic alterations in senescent cells. Because senescence differs greatly depending on cell type and senescence inducer, continued progress in the characterization of senescent cells is needed. Here, we analyzed primary human mammary epithelial cells (HMECs), a model system for aging, using mass spectrometry-based proteomics. By integrating data from replicative senescence, immortalization by telomerase reactivation, and drug-induced senescence, we identified a robust proteomic signature of HMEC senescence consisting of 77 upregulated and 36 downregulated proteins. This approach identified known biomarkers, such as downregulation of the nuclear lamina protein lamin-B1 (LMNB1), and novel upregulated proteins including the β-galactoside-binding protein galectin-7 (LGALS7). Gene ontology enrichment analysis demonstrated that senescent HMECs upregulated lysosomal proteins and downregulated RNA metabolic processes. We additionally integrated our proteomic signature of senescence with transcriptomic data from senescent HMECs to demonstrate that our proteomic signature can discriminate proliferating and senescent HMECs even at the transcriptional level. Taken together, our results demonstrate the power of proteomics to identify cell type-specific signatures of senescence and advance the understanding of senescence in primary HMECs.
Project description:TGFβ is known to be a potent inducer of EMT, a process involved in tumor invasion. TIF1γ has been reported to participate to TGFβ signaling. In order to understand the role of TIF1γ in TGFβ signaling and its requirement for EMT, we analyzed the TGFβ1 response of human mammary epithelial cell lines. A strong EMT increase was observed in TIF1γ-silenced cells after TGFβ1 treatment, whereas Smad4 inactivation completely blocked this process. In support of these observations, microarray data show that the functions of several TIF1γ target genes can be linked to EMT. As a negative regulator of Smad4, TIF1γ could be critical for the regulation of TGFβ signaling. This work highlights the molecular relationship between TIF1γ and Smad4 in TGFβ1 signaling and EMT. Total mRNA extractions were performed for 11 samples from transfected HMEC-TR. Replicates are rimo1, 6; rimo3, 9; rimo2, 7; rimo 4, 10 and rimo 5, 11. Rimo 8 is a single experiment. All RNA extractions were obtained from two independent cell cultures excepted for rimo8. Rimo 1, 6 are replicate for ctrl-; Rimo 3, 9 are replicate for ctrl+; Rimo 2, 7 are replicate for SiTIF-; Rimo 4, 10 are replicate for SiTIF+; Rimo8 is SiSmad4-; and Rimo5, 11 are replicate for SiSmad4+. ctrl means that HMEC-TR were transfected with an SiRNA scramble. "siSmad4" means that HMEC-TR were transfected with an SiRNA anti Smad4. "siTIF" means that HMEC-TR were transfected with an SiRNA anti TIF1γ. "-" means that cells were grown without TGFβ. "+" means that cells were treated with 5 ng/ml TGFβ1 for 24h.