Project description:Cellular senescence is a stable arrest of proliferation and is considered a key component of processes associated with carcinogenesis and other ageing-related phenotypes. However, till now, biological markers that define senescence on a genome-wide scale have been limited. Here, we report a DNA methylomic analysis of actively dividing and deeply senescent normal human epithelial cells, identifying 3,852 senescence-associated differentially methylated positions (senDMPs). We find that this human senDMP signature is positively and significantly correlated with both cancer and ageing-associated methylomic dynamics. We also identify germline genetic variants, including those associated with the p16INK4A locus, that are associated with the presence of in vivo senDMP signatures. Importantly, we also demonstrate that the senDMP signature can be effectively reversed in a newly-developed protocol of transient cellular rejuvenation. The senDMP signature has significant potential for understanding some of the key (epi)genetic etiological factors that lead to cancer and age-related diseases in humans. Total RNA obtained from the HMECs at early passage (EP) and deep senescence (DS)
Project description:Cellular senescence is a stable arrest of proliferation and is considered a key component of processes associated with carcinogenesis and other ageing-related phenotypes. However, till now, biological markers that define senescence on a genome-wide scale have been limited. Here, we report a DNA methylomic analysis of actively dividing and deeply senescent normal human epithelial cells, identifying 3,852 senescence-associated differentially methylated positions (senDMPs). We find that this human senDMP signature is positively and significantly correlated with both cancer and ageing-associated methylomic dynamics. We also identify germline genetic variants, including those associated with the p16INK4A locus, that are associated with the presence of in vivo senDMP signatures. Importantly, we also demonstrate that the senDMP signature can be effectively reversed in a newly-developed protocol of transient cellular rejuvenation. The senDMP signature has significant potential for understanding some of the key (epi)genetic etiological factors that lead to cancer and age-related diseases in humans. Bisulphite converted DNA from the HMECs at early passage (EP), deep senescence (DS), deep senescence + p16 siRNA (DS+p16siRNA) at two different time points and FACS for cell cycle at EP were hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:Cellular senescence is a stable arrest of proliferation and is considered a key component of processes associated with carcinogenesis and other ageing-related phenotypes. However, till now, biological markers that define senescence on a genome-wide scale have been limited. Here, we report a DNA methylomic analysis of actively dividing and deeply senescent normal human epithelial cells, identifying 3,852 senescence-associated differentially methylated positions (senDMPs). We find that this human senDMP signature is positively and significantly correlated with both cancer and ageing-associated methylomic dynamics. We also identify germline genetic variants, including those associated with the p16INK4A locus, that are associated with the presence of in vivo senDMP signatures. Importantly, we also demonstrate that the senDMP signature can be effectively reversed in a newly-developed protocol of transient cellular rejuvenation. The senDMP signature has significant potential for understanding some of the key (epi)genetic etiological factors that lead to cancer and age-related diseases in humans. Bisulphite converted DNA from the HMECs at early passage (EP), deep senescence (DS), deep senescence + p16 siRNA (DS+p16siRNA) at two different time points and FACS for cell cycle at EP were hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:Among the different chemotherapies available, genotoxic drugs are widely used. In response to these drugs, particularly doxorubicin, tumor cells can enter into senescence. Chemotherapy-induced senescence (CIS) is a complex response. Long described as a definitive arrest of cell proliferation, we and various groups have shown that this state may not be complete and could allow certain cells to reproliferate. The mechanism could be due to the activation of new signaling pathways. In the laboratory, we study the proteins involved in these pathways and triggering cell proliferation. In this study, we determine a new role for Anterior Gradient protein 2 (AGR2) in vivo in patients and in vitro in a senescence escape model. We used proteomic studies of patients’ samples and cell lines, and also RNA interference to assess the implication of AGR2 in breast cancer and proliferation of senescent cells. First, we identified AGR2, and found that its concentration is higher in the serum of breast cancer patients and that this high concentration is associated with metastasis occurrence. We also observed an inverse correlation between intratumoral AGR2 expression and the senescence marker p16. This observation led us to study AGR2’s role in the CIS escape model. In this model, we found that AGR2 is overexpressed in cells during senescence escape and its loss considerably reduces that phenomenon. Furthermore, we showed that the extracellular form eAGR2 stimulated the reproliferation of senescent cells. The power of proteomic analysis based on the SWATH-MS approach allowed us to highlight the mTOR/AKT signaling pathway in the senescence escape mechanism mediated by AGR2. Analysis of the two signaling pathways revealed that AGR2 modulates RICTOR phosphorylation. All these results show that AGR2 is a breast cancer biomarker and regulates CIS escape via activation of the mTORC2/AKT signaling pathway.
Project description:Pre-mRNA splicing is regulated through combinatorial activity of RNA motifs including splice sites and splicing regulatory elements (SREs). Here, we show that the activity of a major class of mammalian SREs is highly sensitive to the strength of the adjacent 5' splice site (5'ss) sequence, and that this has important functional and evolutionary implications. Activity of G-run SREs was higher for intermediate strength 5'ss by ~4-fold relative to weak 5'ss, and by ~1.3-fold relative to strong 5'ss. The dependence on 5'ss strength was supported both by comparative genomics and by microarray and Illumina mRNA-Seq analyses of splicing changes following RNAi against the splicing factor heterogeneous nuclear ribonucleoprotein (hnRNP) H, which binds G-runs. This dependence implies that the responsiveness of exons to changes in hnRNP H levels is a bivariate function of both SRE abundance and 5'ss strength; this relationship may hold also for other splicing factors. This pattern of activity enables G-runs and hnRNP H to buffer the effects of 5'ss mutations, augmenting both the frequency of 5'ss polymorphism and the evolution of new splicing patterns. Examine mRNA expression in 293T cells following hnRNP H or control siRNA knockdown
Project description:Estrogen receptor M-NM-1 (ERM-NM-1) is a nuclear receptor that is the driving transcription factor expressed in the majority of breast cancers. Recent studies have demonstrated that the liver receptor homolog-1 (LRH-1), another nuclear receptor, is ERM-NM-1-regulated in breast cancer cells. Further, LRH-1 stimulates proliferation and promotes motility and invasion of breast cancer cells. To determine the mechanisms of LRH-1 action in breast cancer cells, we carried out gene expression microarray analysis following siRNA-mediated LRH-1 knockdown. Interestingly, gene ontology (GO) category enrichment analysis of the genes differentially regulated in the presence or absence of LRH-1 identified estrogen responsive genes as the most highly enriched GO categories. To further define LRH-1 target genes, we performed chromatin immunoprecipitation coupled to massively parallel sequencing (ChIP-seq) to identify genomic targets of LRH-1. Remarkably, ChIP-seq showed LRH-1 binding at many ERM-NM-1 binding sites. Analysis of select binding sites confirmed regulation of ERM-NM-1-regulated genes by LRH-1 through binding to estrogen response elements, as exemplified by the TFF1/pS2 gene. Finally, LRH-1 over-expression stimulated ERM-NM-1 recruitment, whilst LRH-1 knockdown reduced ERM-NM-1 recruitment to ERM-NM-1 binding sites. Taken together, our findings establish a key role for LRH-1 in the regulation of ERM-NM-1 target genes in breast cancer cells and identify a mechanism in which co-operative binding of LRH-1 and ERM-NM-1 at estrogen response elements controls the expression of estrogen-responsive genes. MCF-7 cells were transfected with LRH-1 siRNA #2, #3, or with a non-targeting siRNA (siControl) for 72 hours. Following assessment of RNA integrity, four biological replicates for each siRNA treatment were used for microarray analysis.
Project description:Mouse models of cancer recapitulate many of the molecular and biological features of the human disease. We sought to exploit these experimental merits in a systematic comparative proteomics search for circulating proteins associated with lung tumor development. In-depth quantitative proteomics was applied to plasmas from three mouse models of lung adenocarcinoma driven by mutant EGFR or Kras or induced by urethane exposure and a mouse model of small cell lung cancer driven by loss of Trp53 and Rb. To further refine our lung cancer-specific and broad carcinoma signatures, we intersected these lung cancer proteome profiles with those from other well-established mouse models of pancreatic, ovarian, colon, prostate and breast cancer, as well as two mouse models of inflammation. A set of proteins regulated by Titf1/Nkx2-1, a master transcription factor in cells from the peripheral airways and a known lineage-survival oncogene in lung cancer was identified in plasmas of mouse models of lung adenocarcinoma. An EGFR network of proteins was discerned in the plasma of mice with lung tumors driven by a mutant human EGFR. Levels of these proteins returned toward baseline upon treatment with a tyrosine kinase inhibitor. Moreover, a distinct plasma signature was uncovered in the Trp53/Rb mutant small cell lung cancer model that included a set of proteins associated with neuroendocrine development. Our studies have identified novel plasma protein signatures among molecularly or histopathologically defined lung cancer subtypes. siRNA transfection experiments were performed in NCI-H3255 and HCC4019 lung adenocarcinoma cell lines using ON-TARGETplus SMARTpool small interfering RNAs (siRNAs) targeting TITF1 (L-019105-01-0005) along with a negative control (ON-TARGETplus siCONTROL nontargeting siRNA pool; D-001810-10-05) obtained from Dharmacon. 400000 cells were seeded in antibiotic-free RPMI-1640 media supplemented with 10% FBS, in 6-well culture plates. The next day, cells were transfected at a final concentration of 100nM siRNA using 6ul DharmaFECT 1 (Dharmacon) according to the manufacturer's instructions. 72-hours post-transfection, RNA was harvested using Trizol (Invitrogen) and protein using RIPA buffer for microarray expression and western blotting, respectively. RNA from TITF1 knockdown and control experiments was profiled by the MSKCC Genomics Core using the Illumina Human HT-12 v3.0 array platform according to manufacturer's instructions. Two biological replicates were profiled for each condition. Resulting data files were exported using GenomeStudio software, log2 transformed, quantile-normalized and analyzed using Partek Genomics Suite (v6.5). Average values of replicates for each gene were then compared between the TITF1 knockdown and non-targeting treatments for each cell line to identify candidate TITF1 regulated genes.
Project description:Analysis of the effect of FoxA1 on gene expression in molecular apocrine breast tumours, by silencing FoxA1 and measuring expression change against a control sample.
Project description:Tissue-specific transcription factors initiate differentiation toward a specialized cell type by inducing transcription-permissive chromatin modifications at target gene promoters, through the recruitment of the SWI/SNF chromatin-remodeling complex (1, 2). The molecular mechanism that regulates the chromatin re-distribution of SWI/SNF in response to differentiation signals is currently unknown. Here we show that the muscle determination factor MyoD and the SWI/SNF structural sub-unit, BAF60c (SMARCD3), form a complex on the regulatory elements of MyoD-target genes in undifferentiated myoblasts, prior to the activation of gene expression. MyoD-BAF60c complex is devoid of the ATP-dependent enzymatic sub-units Brg1 and Brm, is required for stable MyoD binding to Ebox sequences, and marks the chromatin for signal-dependent recruitment of the SWI/SNF core complex to muscle loci. BAF60c phosphorylation on a conserved threonine by differentiation-activated p38 signalling promotes the incorporation of MyoD-BAF60c into a Brg1-based SWI/SNF complex, which is competent to remodel the chromatin and activates transcription of MyoD-target genes. Our data support an unprecedented two-step model, by which pre-assembled BAF60c-MyoD complex directs the SWI/SNF complex chromatin re-distribution to muscle loci in response to differentiation cues. Differentiation of C2C12 cells individually interfered for BRG1, BAF60B, BAF60C
Project description:To study the biological and functional role of vimentin in maintenance of the mesenchymal phenotype of mammary epithelial cells, vimentin was silenced in the non-transformed MCF10A cells and vimentin-dependent changes in gene expression were analyzed. Scrambled is the siScr-transfected control with two replicates; KD the sample with vimentin knockdown, also two replicates.