The cyclin-dependent kinase inhibitor p21WAF1/Cip1 is the prototype downstream effector of the tumor suppressor protein p53. Yet, evidence from human cancer and mice models, imply that p21WAF1/Cip1, under certain conditions, can exercise oncogenic activity. The mechanism behind this behavior is still obscure. Within this context we unexpectedly noticed, predominantly in p53 mutant human cancers, that a subset of highly atypical cancerous cells expressing strongly p21WAF1/Cip1 demonstrated also signs of proliferation. This finding suggests either tolerance to high p21WAF1/Cip1 levels or that p21WAF1/Cip1 per se guided a selective process that led to more aggressive off-springs. To address the latter scenario we employed p21WAF1/Cip1-inducible p53-null cellular models and monitored them over a prolonged time period, using high-throughput screening means. After an initial phase characterized by stalled growth, mainly due to senescence, a subpopulation of p21WAF1/Cip1 cells emerged, demonstrating increased genomic instability, aggressiveness and chemo-resistance. At the mechanistic level unremitted p21WAF1/Cip1 production saturates the CRL4CDT2 and SCFSkp2 ubiquitin ligase complexes reducing the turn-over of the replication licensing machinery. Deregulation of replication licensing triggered replication stress fuelling genomic instability. Conceptually, the above notion should be considered when anti-tumor strategies are designed, since p21WAF1/Cip1 responds also to p53-independent signals, including various chemotherapeutic compounds.
Chronic p53-independent p21 expression causes genomic instability by deregulating replication licensing.
Specimen part, Cell line
View SamplesWhether epidermal factors play a primary role in immune-mediated skin diseases such as psoriasis is unknown. We now show that the pro-differentiation transcription factor Grainyhead-like 3 (GRHL3), essential during epidermal development but dispensable in adult skin homeostasis, is required for barrier repair after adult epidermal injury. Consistent with activation of a GRHL3-regulated repair pathway in psoriasis, we find GRHL3 up-regulation in lesional skin where GRHL3 binds known epidermal differentiation gene targets. Furthermore, we show the functionality of this pathway in the Imiquimod mouse model of immune-mediated epidermal hyperplasia where loss of Grhl3 exacerbates the epidermal damage response, conferring greater sensitivity to disease induction, delayed resolution of epidermal lesions, and resistance to anti-IL-22 therapy. ChIP-seq and gene expression profiling studies show that while GRHL3 regulates differentiation genes both in development and during repair from immune-mediated damage, it targets distinct sets of genes in the two processes. In particular, GRHL3 suppresses a number of alarmin and other pro-inflammatory genes after immune injury. This study identifies a GRHL3-regulated epidermal barrier repair pathway that suppresses disease initiation and helps resolve existing lesions in immune-mediated epidermal hyperplasia.
A GRHL3-regulated repair pathway suppresses immune-mediated epidermal hyperplasia.
Sex, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Chromatin H3K27me3/H3K4me3 histone marks define gene sets in high-grade serous ovarian cancer that distinguish malignant, tumour-sustaining and chemo-resistant ovarian tumour cells.
Age, Specimen part, Disease stage, Cell line
View SamplesWe describe and illustrate the use of a method to measure nascent nuclear gene transcription with an Array-based Nuclear Run-On (ANRO) assay using commercial microarray platforms.
Time-dependent c-Myc transactomes mapped by Array-based nuclear run-on reveal transcriptional modules in human B cells.
Cell line, Treatment
View SamplesHuman primary keratinocytes were collected at 0, 1, 3, 6, 12, 24 and 48 hours after addition of 1.8mM Calcium and RNA was extracted.
GRHL3/GET1 and trithorax group members collaborate to activate the epidermal progenitor differentiation program.
Time
View SamplesInvestigation of malignancy-associated expression of gene sets based on ovarian tumour histone modification status.
Chromatin H3K27me3/H3K4me3 histone marks define gene sets in high-grade serous ovarian cancer that distinguish malignant, tumour-sustaining and chemo-resistant ovarian tumour cells.
Age, Disease stage
View SamplesPaired platinum-sensitive & platinum-resistant cell lines PEO1 and PEO4 (respectively) were derived from the same patient. Cell line cultures were profiled with the HT-HGU133a GeneChip to investigate chemotherapy resistance related expression of genes marked with different histone modifications in a primary ovarian tumour (clinical data for the primary ovarian tumour is available as Series supplementary file).
Chromatin H3K27me3/H3K4me3 histone marks define gene sets in high-grade serous ovarian cancer that distinguish malignant, tumour-sustaining and chemo-resistant ovarian tumour cells.
Specimen part, Cell line
View SamplesHuman primary keratinocytes were depleted of GRHL3 by siRNA and induced to differentiated for 2 days by addition of Calcium
GRHL3/GET1 and trithorax group members collaborate to activate the epidermal progenitor differentiation program.
Specimen part, Treatment
View Samples41 volunteers (male non-smokers) were exposed to formaldehyde (FA) vapors for 4 h per day over a period of 5 working days under strictly controlled conditions. For each exposure day, different exposure concentrations were used in a random order ranging from 0 up to 0.7 ppm. At concentrations of 0.3 ppm and 0.4 ppm, four peaks of 0.6 or 0.8 ppm for 15 min each were applied. During exposure, subjects had to perform bicycle exercises (about 80 W) four times for 15 min. Blood samples, exfoliated nasal mucosa cells and nasal biopsies were taken before the first and after the last exposure. Nasal epithelial cells were additionally sampled 1, 2 and 3 weeks after the end of the exposure period. The alkaline comet assay, the sister chromatid exchange (SCE) test and the cytokinesis-block micronucleus test (CBMNT) were performed with blood samples. The micronucleus test (MNT) was also performed with exfoliated nasal mucosa cells. The expression (mRNA level) of the GSH-dependent formaldehyde dehydrogenase (FDH, identical to alcohol dehydrogenase 5; ADH5; EC 1.2.1.46) was measured in blood samples by quantitative real-time RT-PCR with TaqMan probes. DNA microarray analyses using a full-genome human microarray were performed on blood samples and nasal biopsies of selected subgroups with the highest FA exposure at different days. None of the tests performed showed a biologically significant effect related to FA exposure. Under the experimental conditions of this study, inhalation of FA did not lead to genotoxic effects in peripheral blood cells and nasal mucosa and had no effect on the expression of the FDH gene. Inhalation of FA also did not cause biologically relevant alterations in the expression of genes in a microarray analysis with nasal biopsies and peripheral blood cells.
Assessment of genotoxic effects and changes in gene expression in humans exposed to formaldehyde by inhalation under controlled conditions.
Sex, Specimen part, Treatment, Subject
View SamplesThe functions of key oncogenic transcription factors independent of context have not been fully delineated despite our richer understanding of the genetic alterations in human cancers. The MYC oncogene, which produces the Myc transcription factor, is frequently altered in human cancer and is a major regulatory hub for many cancers. In this regard, we sought to unravel the primordial signature of Myc function by using high-throughput genomic approaches to identify the cell-type independent core Myc target gene signature. Using a model of human B lymphoma cells bearing inducible MYC, we identified a stringent set of direct Myc target genes via chromatin immunoprecipitation (ChIP), global nuclear run-on assay, and changes in mRNA levels. We also identified direct Myc targets in human embryonic stem cells (ESCs). We further document that a Myc core signature (MCS) set of target genes is shared in mouse and human ESCs as well as in four other human cancer cell types. Remarkably, the expression of the MCS correlates with MYC expression in a cell-type independent manner across 8,129 microarray samples, which include 312 cell and tissue types. Furthermore, the expression of the MCS is elevated in vivo in Em-Myc transgenic murine lymphoma cells as compared with premalignant or normal B lymphocytes. Expression of the MCS in human B cell lymphomas, acute leukemia, lung cancers or Ewing sarcomas has the highest correlation with MYC expression. Annotation of this gene signature reveals Myc's primordial function in RNA processing, ribosome biogenesis and biomass accumulation as its key roles in cancer and stem cells.
Cell-type independent MYC target genes reveal a primordial signature involved in biomass accumulation.
Specimen part, Cell line, Treatment
View Samples