Project description:We previously identified the induction of growth arrest with phenotypic characteristics of senescence in melanoma cell lines sensitive to diterpene esters, indicating a therapeutic potential. Here we compared the cytostatic effects of two diterpene esters namely TPA (12-O-tetradecanoylphorbol-13-acetate) and PEP008 (20-O-acetyl-ingenol-3-angelate) in sensitive and resistant cell lines derived from melanoma, breast cancer and colon cancer. We showed the diterpene esters to induce senescence-like growth arrest in the sensitive cells at 100-1000 ng/ml. Use of the pan-PKC inhibitor bisindolylmaleimide-l demonstrated that activation of PKC was required for growth arrest. Full genome expression profiling revealed that pivotal genes involved in DNA synthesis and cell cycle control were down-regulated by treatment in all three sensitive solid tumor models. At the protein level, prolonged down-regulation of E2F-1 and proliferating cell nuclear antigen (PCNA), sustained expression of p21WAF1/CIP1 and dephosphorylation of retinoblastoma (Rb) occurred in the sensitive cells. Although activation of extracellular signal-related kinase (ERK) 1/2 by the diterpene esters occurred in both sensitive and resistant cell lines, the HRASLS3 type II tumor suppressor, which appears to have a role in MAPK pathway suppression, was constitutively elevated in the resistant cell lines compared to their sensitive counterparts. Together, these results demonstrate the ability of the PKC activating drugs TPA and PEP008 to induce growth arrest with characteristics of senescence in solid tumor cell lines derived from a variety of tissue types through a similar mechanism. PKC-activating diterpene esters may therefore have therapeutic potential in a range of solid tumors. Experiment Overall Design: We analyzed the transcriptional profiles of the diterpene ester sensitive cell lines MCF7, COLO-205 and SK-MEL-5 following treatment with PEP008 using full genome expression profiling (Affymetrix, U133 Plus 2.0). Cells were treated for 24 h and 24 h plus 72 h recovery with 1000 ng/ml of the drug, before harvesting RNA for analysis. From the cell growth assays, all three cell lines demonstrated permanent growth arrest with diterpene ester treatments at the 1000 ng/ml dose. Mock controls were treated with solvent alone for 24 h. SK-MEL-5 cells were also treated with 1000 ng/ml TPA for 24 h.
Project description:We previously identified the induction of growth arrest with phenotypic characteristics of senescence in melanoma cell lines sensitive to diterpene esters, indicating a therapeutic potential. Here we compared the cytostatic effects of two diterpene esters namely TPA (12-O-tetradecanoylphorbol-13-acetate) and PEP008 (20-O-acetyl-ingenol-3-angelate) in sensitive and resistant cell lines derived from melanoma, breast cancer and colon cancer. We showed the diterpene esters to induce senescence-like growth arrest in the sensitive cells at 100-1000 ng/ml. Use of the pan-PKC inhibitor bisindolylmaleimide-l demonstrated that activation of PKC was required for growth arrest. Full genome expression profiling revealed that pivotal genes involved in DNA synthesis and cell cycle control were down-regulated by treatment in all three sensitive solid tumor models. At the protein level, prolonged down-regulation of E2F-1 and proliferating cell nuclear antigen (PCNA), sustained expression of p21WAF1/CIP1 and dephosphorylation of retinoblastoma (Rb) occurred in the sensitive cells. Although activation of extracellular signal-related kinase (ERK) 1/2 by the diterpene esters occurred in both sensitive and resistant cell lines, the HRASLS3 type II tumor suppressor, which appears to have a role in MAPK pathway suppression, was constitutively elevated in the resistant cell lines compared to their sensitive counterparts. Together, these results demonstrate the ability of the PKC activating drugs TPA and PEP008 to induce growth arrest with characteristics of senescence in solid tumor cell lines derived from a variety of tissue types through a similar mechanism. PKC-activating diterpene esters may therefore have therapeutic potential in a range of solid tumors. Keywords: time course
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression. Two-condition experiment, Normoxic MSCs vs. Hypoxic MSCs.
Project description:The growth arrest and DNA-damage induced 45 gamma (GADD45g) is rapidly induced by various physiological and environmental stresses associated with growth arrest. GADD45g has been observed implicated in cell survival, apoptosis, senescence, cell cycle regulation and DNA repair in a variety of human solid tumor types, acting as either tumor promoter or tumor suppressor. To date, the role of GADD45g in hematopoietic malignancies remains completely unknown. Here, we transduced Molm-13 cells with lentiviral vectors expressing doxycycline-inducible GADD45g. Molm-13 cells with dox administration or not were collected for RNA-seq.
Project description:Aberrant activation of the ERK signaling pathway triggers a protective anticancer response characterized by stable growth arrest and activation of tumor suppressors called cellular senescence. Pancreatic adenocarcinomas (PDAC) often possess mutations in K-Ras that activate the ERK pathway. Pancreatic intraepithelial neoplasia of low degree display high levels of phospho-ERK consistent with senescence acting as a barrier for malignant transformation. However, advanced lesions downregulate phospho-ERK levels circumventing the senescence barrier. Restoring ERK hyperactivation in PDAC using an activated allele of the kinase RAF, leads to ERK-dependent growth arrest with senescence biomarkers. Phosphoproteomics analysis of ERK-dependent senescence in PDAC revealed a decrease in several nucleolar phosphoproteins suggesting that high levels of ERK lead to senescence via nucleolar stress. Consistent with this explanation, ERK-dependent senescent cells displayed intranucleolar foci containing RNA polymerase I. Combining ribosome biogenesis inhibitors with ERK hyperactivation reinforced the senescence response of PDAC cells. The drug cocktail FOLFIRINOX, currently the best treatment for PDAC, also triggered ERK hyperactivation and nucleolar stress characterized by nucleolar foci, solid amyloid aggregates and a decrease in 5.8S and 28S rRNAs. We thus suggest that drugs targeting ribosome biogenesis can improve the senescence anticancer response in pancreatic cancer.
Project description:Immune checkpoint bloackade (ICB)-based or natural cancer immune responses largely eliminate tumours. Yet, they require additional mechanisms to arrest those cancer cells that are not rejected. Cytokine-induced senescence (CIS) can stably arrest cancer cells, suggesting that interferon-dependent induction of senescence-inducing cell cycle regulators is needed to control those cancer cells that escape from killing. Here we report in two different cancers sensitive to T cell-mediated rejection, we show that deletion of the senescence-inducing cell cycle regulators p16Ink4a/p19Arf (Cdkn2a) or p21Cip1 (Cdkn1a) in the tumour cells abrogated both, the natural and the ICB-induced cancer immune control. Also in humans, melanoma metastases that progressed rapidly during ICB have losses of senescence-inducing genes and amplifications of senescence inhibitors. Metastatic cells also resist CIS. Such genetic and functional alterations are infrequent in metastatic melanomas regressing during ICB. Thus, activation of tumour-intrinsic, senescence-inducing cell cycle regulators is required to stably arrest those cancer cells that escape from eradication.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.