Project description:Melanocytes within benign human nevi are the paradigm for tumor suppressive senescent cells in a pre-malignant neoplasm. These cells typically contain mutations in either the BRAF or N-RAS oncogene and express markers of senescence, including p16. However, a nevus can contain 10s to 100s of thousands of clonal melanocytes and approximately 20-30% of melanoma are thought to arise in association with a pre-existing nevus. Neither observation is indicative of fail-safe senescence-associated proliferation arrest and tumor suppression. We set out to better understand the status of nevus melanocytes. Proliferation-promoting Wnt target genes, such as cyclin D1 and c-myc, were repressed in oncogene-induced senescent melanocytes in vitro, and repression of Wnt signaling in these cells induced a senescent-like state. In contrast, cyclin D1 and c-myc were expressed in many melanocytes of human benign nevi. Specifically, activated Wnt signalling in nevi correlated inversely with nevus maturation, an established dermatopathological correlate of clinical benignancy. Single cell analyses of lone epidermal melanocytes and nevus melanocytes showed that expression of proliferation-promoting Wnt targets correlates with prior proliferative expansion of p16-expressing nevus melanocytes. In a mouse model, activation of Wnt signaling delayed, but did not bypass, senescence of oncogene-expressing melanocytes, leading to massive accumulation of proliferation-arrested, p16-positive non-malignant melanocytes. We conclude that clonal hyperproliferation of oncogene-expressing melanocytes to form a nevus is facilitated by transient delay of senescence due to activated Wnt signaling. The observation that activation of Wnt signaling correlates inversely with nevus maturation, an indicator of clinical benignancy, supports the notion that persistent destabilization of senescence by Wnt signaling contributes to the malignant potential of nevi. We used microarrays to detail the global programme of gene expression after lentiviral infection of BRAF in 3 replicates. Primary human melanocytes were infected/uninfected with lentivirus containing either an Empty Vector or activated BRAFV600E mutant in three biological replicates
Project description:Cellular senescence is a stable proliferation arrest associated with an altered secretory pathway, the Senescence-Associated Secretory Phenotype (SASP). However, cellular senescence is initiated by diverse molecular triggers, such as activated oncogenes and shortened telomeres, and is associated with varied and complex physiological endpoints, such as tumor suppression and tissue aging. The extent to which distinct triggers activate divergent modes of senescence that might be associated with different physiological endpoints is largely unknown. To begin to address this, we performed gene expression profiling to compare the senescence programs associated with two different modes of senescence, oncogene-induced senescence (OIS) and replicative senescence (RS [in part caused by shortened telomeres]). While both OIS and RS are associated with many common changes in gene expression compared to control proliferating cells, they also exhibit substantial differences. These results are discussed in light of potential physiological consequences, tumor suppression and aging. We used microarrays to detail the global programme of gene expression after oncogene induced senescence.
Project description:The mammalian HIRA/UBN1/ASF1a complex is a histone chaperone complex that is conserved from yeast (Saccharomyces cerevisiae) to humans. This complex preferentially deposits the histone variant H3.3 into chromatin in a DNA replication-independent manner and is implicated in diverse chromatin regu- latory events from gene activation to heterochromatinization. In yeast, the orthologous complex consists of three Hir proteins (Hir1p, Hir2p, and Hir3p), Hpc2p, and Asf1p. Yeast Hir3p has weak homology to CABIN1, a fourth member of the human complex, suggesting that Hir3p and CABIN1 may be orthologs. Here we show that HIRA and CABIN1 interact at ectopic and endogenous levels of expression in cells, and we isolate the quaternary HIRA/UBN1/CABIN1/ASF1a (HUCA) complex, assembled from recombinant proteins. Mutational analyses support the view that HIRA acts as a scaffold to bring together UBN1, ASF1a, and CABIN1 into a quaternary complex. We show that, like HIRA, UBN1, and ASF1a, CABIN1 is involved in heterochromatinization of the genome of senescent human cells. Moreover, in proliferating cells, HIRA and CABIN1 regulate overlapping sets of genes, and these genes are enriched in the histone variant H3.3. In sum, these data demonstrate that CABIN1 is a functional member of the human HUCA complex and so is the likely ortholog of yeast Hir3p. We used microarrays to detail the global programme of gene expression after knockdown of HIRA and CABIN1 in 3 replicates HeLa cells were nucleofacted with Dharmacon control siRNA and siRNA to HIRA and CABIN1 and RNA was isolated 72 hours after transfection.
Project description:Mutations in both RAS and the PTEN/PIK3CA/AKT signaling module are found in the same human tumors. PIK3CA and AKT are downstream effectors of RAS, and the selective advantage conferred by mutation of two genes in the same pathway is unclear. Based on a comparative molecular analysis, we show that activated PIK3CA/AKT is a weaker inducer of senescence than is activated RAS. More-over, concurrent activation of RAS and PIK3CA/AKT impairs RAS-induced senescence. We used microarrays to detail the global programme of gene expression after transduction of AKT and RAS IMR90 cells were transfected with Control, AKT and RAS retrovirus containing medium in 4 replicates. Fibroblasts were drug selected and kept in drug for duration of experiments.
Project description:Melanocytes within benign human nevi are the paradigm for tumor suppressive senescent cells in a pre-malignant neoplasm. These cells typically contain mutations in either the BRAF or N-RAS oncogene and express markers of senescence, including p16. However, a nevus can contain 10s to 100s of thousands of clonal melanocytes and approximately 20-30% of melanoma are thought to arise in association with a pre-existing nevus. Neither observation is indicative of fail-safe senescence-associated proliferation arrest and tumor suppression. We set out to better understand the status of nevus melanocytes. Proliferation-promoting Wnt target genes, such as cyclin D1 and c-myc, were repressed in oncogene-induced senescent melanocytes in vitro, and repression of Wnt signaling in these cells induced a senescent-like state. In contrast, cyclin D1 and c-myc were expressed in many melanocytes of human benign nevi. Specifically, activated Wnt signalling in nevi correlated inversely with nevus maturation, an established dermatopathological correlate of clinical benignancy. Single cell analyses of lone epidermal melanocytes and nevus melanocytes showed that expression of proliferation-promoting Wnt targets correlates with prior proliferative expansion of p16-expressing nevus melanocytes. In a mouse model, activation of Wnt signaling delayed, but did not bypass, senescence of oncogene-expressing melanocytes, leading to massive accumulation of proliferation-arrested, p16-positive non-malignant melanocytes. We conclude that clonal hyperproliferation of oncogene-expressing melanocytes to form a nevus is facilitated by transient delay of senescence due to activated Wnt signaling. The observation that activation of Wnt signaling correlates inversely with nevus maturation, an indicator of clinical benignancy, supports the notion that persistent destabilization of senescence by Wnt signaling contributes to the malignant potential of nevi. We used RNA-Seq to detail the global programme of gene expression in primary human melanocytes which were Uninfected and BRAF600V induced cells
Project description:NOD mice were injected once a week with LTBR-Ig to block the LTBR-pathway, or with control monoclonal antibody MOPC from age 8 to 16 weeks old. Extraorbital lacrimal glands or submaxillary glands were dissected and total mRNA prepared. Each sample was either the combined lacrimals (2) from each mouse or individual salivary glands. There were 4 mice in each treatment group. Total mRNA was isolated and the quality was assessed using the Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA). Reverse transcription to prepare cDNA was performed using Invitrogen M-MLV system. The purpose was to determine changes in gene expression in glands due to blockade of the LTBR-pathway. Differential Gene Expression in NOD mouse lacrimal and salivary glands after LTBR-Ig treatment
Project description:Whole blood expression was profiled in Rheumatoid Arthiritis and SLE (Systemic LUPUS Erythomatosus) patients. Expression in the whole blood of RA and SLE patients, comparing gene expression signatures in SLE, and RA DMARD-IR and RA TNF-IR patients. This is baseline whole blood expression data for 3 patient populations (SLE, RA DMARD-IR and RA TNF-IR) and 20 Controls.
Project description:We used microarrays to detail the global program of gene expression underlying the effect of p17 on human plasmacytoid dendritic cells and was compared to CpG profile. Experiment Overall Design: Human plasmacytoid dendritic cells were purified from two donors and cultured in the presence of p17 or CpG for 18 h.
Project description:Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant CNS neoplasm whichprimarily occurs in children under three years of age. Due to poor outcomes with intense and toxicmultimodality treatment, new therapies are urgently needed. Histone deacetylase inhibitors (HDIs)have been evaluated as novel agents for multiple malignancies and have been shown to function asradiosensitizers. They act as epigenetic modifiers and lead to re-expression of inappropriatelyrepressed genes, proteins, and cellular functions. Due to the underlying chromatin remodeling genemutation in ATRT, HDIs are ideal candidates for therapeutic evaluation. To evaluate the role of HDIsagainst ATRT in vitro, we assessed the effect of drug treatment on proliferation, apoptosis, and geneexpression. Additionally, we examined HDI pretreatment as a radiosensitization strategy for ATRT.MTS and clonogenic assays demonstrated that HDI treatment significantly reduces the proliferativecapacity of BT-12 and BT-16 ATRT cells. Also, the HDI SNDX-275 was able to induce apoptosis in bothcell lines and induced p21Waf1/Cip1 protein expression as measured by Western blot. Evaluation ofdifferential gene expression by microarray and pathway analysis after HDI treatment demonstratedalterations of several key ATRT cellular functions. Finally, we showed that HDI pretreatmenteffectively potentiates the effect of ionizing radiation on ATRT cells as measured by clonogenic assay.These findings suggest that the addition of HDIs to ATRT therapy may prove beneficial, especiallywhen administered in combination with current treatment modalities such as radiation. Keywords: ATRT; HDAC inhibitor; radiosensitization BT12 and BT16 cells were plated and subsequently treated for 24hr with IC25 concentrations of SNDX-275 (Sigma), at which time total RNA was collected. IC25 concentrations were calculated based on MTS assay.For BT12, the SNDX-275 IC25 was 1.4uM. For BT16, it was 0.44uM. The controls had DMSO added at equivalent volumes.
Project description:Myelodysplastic syndrome (MDS) is considered a disease of hematopoietic stem cell (HSC) origin. To begin to unravel the molecular mechanisms underlying the deregulation of HSCs in MDS, we performed comparative gene expression profiling on Crebbp+/- and wild type HSCs. We chose to isolate HSCs from the fetal liver (FLHSC) because at this stage there were no differences in cell number between Crebbp+/- and wild type fetal livers, suggesting no overt hematopoietic differences. Thus, any change in gene expression found in Crebbp+/- FLHSCs is likely to reflect the initially compromised genetic program of HSC regulation, as opposed to that of Crebbp+/- HSCs in adult bone marrow, where secondary changes in gene expression may also occur as compensatory mechanisms for a compromised or failing hematopoietic system. We used day 14.5 post coitus FLHSC (Sca-1+,Lin-,AA4.1+,c-Kit++) from wild type (wt) and Crebbp heterozygous (ht) embryos to examine changes in gene expression before overt myelodysplastic disease manifestation. Total RNA from wt and Crebbp+/- FLHSCs was isolated, PCR-amplified using the Ovation RNA amplification system and hybridized to Affymetrix Mouse 430 2.0 expression microarrays.