Publications by authors named "Gerardo Ferbeyre"

87 Publications

Oxidative stress-induced senescence mediates inflammatory and fibrotic phenotypes in fibroblasts from systemic sclerosis patients.

Rheumatology (Oxford) 2021 Jun 11. Epub 2021 Jun 11.

Faculty of Pharmacy, Université de Montréal, Québec, Canada.

Objective: Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by inflammation and fibrosis. Although constitutive activation of fibroblasts is proposed to be responsible for the fibrotic and inflammatory features of the disease, the underlying mechanism remains elusive and, effective therapeutic targets are still lacking. The aim of this study was to evaluate the role of oxidative stress-induced senescence and its contribution to the pro-fibrotic and pro-inflammatory phenotypes of fibroblasts from SSc patients.

Methods: Dermal fibroblasts were isolated from SSc (n = 13) and healthy (n = 10) donors. Fibroblast's intracellular and mitochondrial reactive oxygen species were determined by flow cytometry. Mitochondrial function measured by Seahorse XF24 analyzer. Fibrotic and inflammatory gene expressions were assessed by qPCR and key pro-inflammatory components of the fibroblasts' secretome (interleukin (IL) 6 and IL8) were quantified by ELISA.

Results: Compared to healthy fibroblasts, SSc fibroblasts displayed higher levels of both intracellular and mitochondrial ROS. Oxidative stress in SSc fibroblasts induced the expression of fibrotic genes and activated the transforming growth factor-β-activated kinase 1 (TAK1) -IκB kinase β (IKKβ)- interferon regulatory factor 5 (IRF5) inflammatory signaling cascade. These cellular responses paralleled the presence of a DNA damage response, a senescence-associated secretory phenotype and a fibrotic response. Treatment of SSc fibroblasts with ROS scavengers reduced their pro-inflammatory secretome production and fibrotic gene expression.

Conclusions: Oxidative stress-induced cellular senescence in SSc fibroblasts underlies their pro-inflammatory and pro-fibrotic phenotypes. Targeting redox imbalance of SSc fibroblasts enhances their in vitro functions and could be of relevance for SSc therapy.
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http://dx.doi.org/10.1093/rheumatology/keab477DOI Listing
June 2021

Phenylethynylbenzyl-modified biguanides inhibit pancreatic cancer tumor growth.

Sci Rep 2021 May 10;11(1):9854. Epub 2021 May 10.

Département de Chimie-Faculté des Arts et des Sciences, Université de Montréal, 2900 Edouard Montpetit, Succursale Centre-Ville, CP 6128, Montreal, QC, H3C3J7, Canada.

We present the design and synthesis of a small library of substituted biguanidium salts and their capacity to inhibit the growth of pancreatic cancer cells. We first present their in vitro and membrane activity, before we address their mechanism of action in living cells and in vivo activity. We show that phenylethynyl biguanidium salts possess higher ability to cross hydrophobic barriers, improve mitochondrial accumulation and anticancer activity. Mechanistically, the most active compound, 1b, like metformin, activated AMPK, decreased the NAD/NADH ratio and mitochondrial respiration, but at 800-fold lower concentration. In vivo studies show that compound 1b significantly inhibits the growth of pancreatic cancer xenografts in mice, while biguanides currently in clinical trials had little activity.
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http://dx.doi.org/10.1038/s41598-021-87993-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110578PMC
May 2021

Osteoclasts protect bone blood vessels against senescence through the angiogenin/plexin-B2 axis.

Nat Commun 2021 03 23;12(1):1832. Epub 2021 Mar 23.

Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Synthetic glucocorticoids (GCs), one of the most effective treatments for chronic inflammatory and autoimmune conditions in children, have adverse effects on the growing skeleton. GCs inhibit angiogenesis in growing bone, but the underlying mechanisms remain unclear. Here, we show that GC treatment in young mice induces vascular endothelial cell senescence in metaphysis of long bone, and that inhibition of endothelial cell senescence improves GC-impaired bone angiogenesis with coupled osteogenesis. We identify angiogenin (ANG), a ribonuclease with pro-angiogenic activity, secreted by osteoclasts as a key factor for protecting the neighboring vascular cells against senescence. ANG maintains the proliferative activity of endothelial cells through plexin-B2 (PLXNB2)-mediated transcription of ribosomal RNA (rRNA). GC treatment inhibits ANG production by suppressing osteoclast formation in metaphysis, resulting in impaired endothelial cell rRNA transcription and subsequent cellular senescence. These findings reveal the role of metaphyseal blood vessel senescence in mediating the action of GCs on growing skeleton and establish the ANG/PLXNB2 axis as a molecular basis for the osteoclast-vascular interplay in skeletal angiogenesis.
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http://dx.doi.org/10.1038/s41467-021-22131-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987975PMC
March 2021

New Insights into CDK Regulators: Novel Opportunities for Cancer Therapy.

Trends Cell Biol 2021 05 3;31(5):331-344. Epub 2021 Mar 3.

Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, QC, H3C 3J7, Canada. Electronic address:

Cyclins and their catalytic partners, the cyclin-dependent kinases (CDKs), control the transition between different phases of the cell cycle. CDK/cyclin activity is regulated by CDK inhibitors (CKIs), currently comprising the CDK-interacting protein/kinase inhibitory protein (CIP/KIP) family and the inhibitor of kinase (INK) family. Recent studies have identified a third group of CKIs, called ribosomal protein-inhibiting CDKs (RPICs). RPICs were discovered in the context of cellular senescence, a stable cell cycle arrest with tumor-suppressing abilities. RPICs accumulate in the nonribosomal fraction of senescent cells due to a decrease in rRNA biogenesis. Accordingly, RPICs are often downregulated in human cancers together with other ribosomal proteins, the tumor-suppressor functions of which are still under study. In this review, we discuss unique therapies that have been developed to target CDK activity in the context of cancer treatment or senescence-associated pathologies, providing novel tools for precision medicine.
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http://dx.doi.org/10.1016/j.tcb.2021.01.010DOI Listing
May 2021

Senescence: A program in the road to cell elimination and cancer.

Semin Cancer Biol 2020 Dec 26. Epub 2020 Dec 26.

Department of Biochemistry and Molecular Medicine and CRCHUM, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7, Canada. Electronic address:

Senescence is a tumor suppressor response that prevents the proliferation of mutated cells and alert the immune system for their elimination. However, this program is not perfect and with time additional genetic and epigenetic changes can impair tumor suppression and promote cancer progression both in cell autonomous and non-cell autonomous manners. A polyploid barrier is implemented in senescent cells to further prevent cell expansion but polyploid cells can generate highly malignant tumor cells via de-polyploidization. The nuclear lamina can act as an additional fail safe to prevent cancer in these cells and drugs able to stabilize the nuclear lamina may help to treat cancers by preventing senescence escape.
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http://dx.doi.org/10.1016/j.semcancer.2020.12.017DOI Listing
December 2020

Lack of consensus on an aging biology paradigm? A global survey reveals an agreement to disagree, and the need for an interdisciplinary framework.

Mech Ageing Dev 2020 10 18;191:111316. Epub 2020 Jul 18.

Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada; Metabolic Disorders and Complications Program, and Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec, H4A 3J1, Canada. Electronic address:

At a recent symposium on aging biology, a debate was held as to whether or not we know what biological aging is. Most of the participants were struck not only by the lack of consensus on this core question, but also on many basic tenets of the field. Accordingly, we undertook a systematic survey of our 71 participants on key questions that were raised during the debate and symposium, eliciting 37 responses. The results confirmed the impression from the symposium: there is marked disagreement on the most fundamental questions in the field, and little consensus on anything other than the heterogeneous nature of aging processes. Areas of major disagreement included what participants viewed as the essence of aging, when it begins, whether aging is programmed or not, whether we currently have a good understanding of aging mechanisms, whether aging is or will be quantifiable, whether aging will be treatable, and whether many non-aging species exist. These disagreements lay bare the urgent need for a more unified and cross-disciplinary paradigm in the biology of aging that will clarify both areas of agreement and disagreement, allowing research to proceed more efficiently. We suggest directions to encourage the emergence of such a paradigm.
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http://dx.doi.org/10.1016/j.mad.2020.111316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603428PMC
October 2020

SOCS1: phosphorylation, dimerization and tumor suppression.

Oncoscience 2019 Nov 23;6(11-12):386-389. Epub 2019 Dec 23.

Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, Québec, Canada.

Suppressor of cytokine signaling (SOCS) family members are upregulated following JAK-STAT pathway activation by cytokines. SOCS proteins are recognized inhibitors of cytokine signaling playing roles in cell growth and differentiation. Moreover, SOCS1 and SOCS3 have been shown to be involved in tumor suppression through their ability to interact with p53 leading to the activation of its transcriptional program and showing the implication of SOCS family members in the regulation of apoptosis, ferroptosis and senescence. More recently, we demonstrated that the SRC family of non-receptor tyrosine kinases (SFK) can phosphorylate SOCS1 leading to its homodimerization and inhibiting its interaction with p53. Then, we reactivated the SOCS1-p53 tumor suppressor axis with the SFK inhibitor dasatinib in combination with the p53 activating compound PRIMA. This work suggests new avenues for cancer treatment and leaves open several new questions that deserve to be addressed.
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http://dx.doi.org/10.18632/oncoscience.495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6959930PMC
November 2019

Metformin turns off the metabolic switch of pancreatic cancer.

Aging (Albany NY) 2019 12 12;11(23):10793-10795. Epub 2019 Dec 12.

CR-CHUM, Université de Montréal, Montréal, Québec, Canada.

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http://dx.doi.org/10.18632/aging.102622DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6932906PMC
December 2019

NFE2L3 Controls Colon Cancer Cell Growth through Regulation of DUX4, a CDK1 Inhibitor.

Cell Rep 2019 11;29(6):1469-1481.e9

Lady Davis Institute for Medical Research, McGill University, Montreal, QC H3T 1E2, Canada; Department of Medicine, McGill University, Montreal, QC H3T 1E2, Canada; Department of Physiology, McGill University, Montreal, QC H3T 1E2, Canada. Electronic address:

Constitutive nuclear factor κB (NF-κB) activation is a hallmark of colon tumor growth. Cyclin-dependent kinases (CDKs) are critical cell-cycle regulators, and inhibition of CDK activity has been used successfully as anticancer therapy. Here, we show that the NFE2L3 transcription factor functions as a key regulator in a pathway that links NF-κB signaling to the control of CDK1 activity, thereby driving colon cancer cell proliferation. We found that NFE2L3 expression is regulated by the RELA subunit of NF-κB and that NFE2L3 levels are elevated in patients with colon adenocarcinoma when compared with normal adjacent tissue. Silencing of NFE2L3 significantly decreases colon cancer cell proliferation in vitro and tumor growth in vivo. NFE2L3 knockdown results in increased levels of double homeobox factor 4 (DUX4), which functions as a direct inhibitor of CDK1. The discovered oncogenic pathway governing cell-cycle progression may open up unique avenues for precision cancer therapy.
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http://dx.doi.org/10.1016/j.celrep.2019.09.087DOI Listing
November 2019

Cellular Senescence: Defining a Path Forward.

Cell 2019 10;179(4):813-827

University of Groningen (RUG), European Research Institute for the Biology of Aging (ERIBA), University Medical Center Groningen (UMCG), Groningen, the Netherlands. Electronic address:

Cellular senescence is a cell state implicated in various physiological processes and a wide spectrum of age-related diseases. Recently, interest in therapeutically targeting senescence to improve healthy aging and age-related disease, otherwise known as senotherapy, has been growing rapidly. Thus, the accurate detection of senescent cells, especially in vivo, is essential. Here, we present a consensus from the International Cell Senescence Association (ICSA), defining and discussing key cellular and molecular features of senescence and offering recommendations on how to use them as biomarkers. We also present a resource tool to facilitate the identification of genes linked with senescence, SeneQuest (available at http://Senequest.net). Lastly, we propose an algorithm to accurately assess and quantify senescence, both in cultured cells and in vivo.
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http://dx.doi.org/10.1016/j.cell.2019.10.005DOI Listing
October 2019

STAT3 and STAT5 Activation in Solid Cancers.

Cancers (Basel) 2019 Sep 25;11(10). Epub 2019 Sep 25.

Department of Biochemistry and Molecular Medicine, Université de Montréal, C.P. 6128, Succ. Centre-Ville, CRCHUM, Montréal, QC H3C 3J7, Canada.

The Signal Transducer and Activator of Transcription (STAT)3 and 5 proteins are activated by many cytokine receptors to regulate specific gene expression and mitochondrial functions. Their role in cancer is largely context-dependent as they can both act as oncogenes and tumor suppressors. We review here the role of STAT3/5 activation in solid cancers and summarize their association with survival in cancer patients. The molecular mechanisms that underpin the oncogenic activity of STAT3/5 signaling include the regulation of genes that control cell cycle and cell death. However, recent advances also highlight the critical role of STAT3/5 target genes mediating inflammation and stemness. In addition, STAT3 mitochondrial functions are required for transformation. On the other hand, several tumor suppressor pathways act on or are activated by STAT3/5 signaling, including tyrosine phosphatases, the sumo ligase Protein Inhibitor of Activated STAT3 (PIAS3), the E3 ubiquitin ligase TATA Element Modulatory Factor/Androgen Receptor-Coactivator of 160 kDa (TMF/ARA160), the miRNAs miR-124 and miR-1181, the Protein of alternative reading frame 19 (p19ARF)/p53 pathway and the Suppressor of Cytokine Signaling 1 and 3 (SOCS1/3) proteins. Cancer mutations and epigenetic alterations may alter the balance between pro-oncogenic and tumor suppressor activities associated with STAT3/5 signaling, explaining their context-dependent association with tumor progression both in human cancers and animal models.
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http://dx.doi.org/10.3390/cancers11101428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6826753PMC
September 2019

The Inability of the Choroid to Revascularize in Oxygen-Induced Retinopathy Results from Increased p53/miR-Let-7b Activity.

Am J Pathol 2019 11 17;189(11):2340-2356. Epub 2019 Aug 17.

Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada; Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Centre, Université de Montréal, Montréal, Québec, Canada; Department of Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Hospital, Université de Montréal, Montréal, Québec, Canada; Department of Ophthalmology, Centre Hospitalier Universitaire Sainte-Justine Hospital, Université de Montréal, Montréal, Québec, Canada; Department of Pediatrics, Sainte-Justine University Hospital Centre, Université de Montréal, Montréal, Québec, Canada. Electronic address:

Retinopathy of prematurity (ROP) is characterized by an initial retinal avascularization, followed by pathologic neovascularization. Recently, choroidal thinning has also been detected in children formerly diagnosed with ROP; a similar sustained choroidal thinning is observed in ROP models. But the mechanism underlying the lack of choroidal revascularization remains unclear and was investigated in an oxygen-induced retinopathy (OIR) model. In OIR, evidence of senescence was detected, preceded by oxidative stress in the choroid and the retinal pigment epithelium. This was associated with a global reduction of proangiogenic factors, including insulin-like growth factor 1 receptor (Igf1R). Coincidentally, tumor suppressor p53 was highly expressed in the OIR retinae. Curtailing p53 activity resulted in reversal of senescence, normalization of Igf1r expression, and preservation of choroidal integrity. OIR-induced down-regulation of Igf1r was mediated at least partly by miR-let-7b as i) let-7b expression was augmented throughout and beyond the period of oxygen exposure, ii) let-7b directly targeted Igf1r mRNA, and iii) p53 knock-down blunted let-7b expression, restored Igf1r expression, and elicited choroidal revascularization. Finally, restoration of Igf1r expression rescued choroid thickness. Altogether, this study uncovers a significant mechanism for defective choroidal revascularization in OIR, revealing a new role for p53/let-7b/IGF-1R axis in the retina. Future investigations on this (and connected) pathway could further our understanding of other degenerative choroidopathies, such as geographic atrophy.
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http://dx.doi.org/10.1016/j.ajpath.2019.07.009DOI Listing
November 2019

Knockdown of angiopoietin-like 2 induces clearance of vascular endothelial senescent cells by apoptosis, promotes endothelial repair and slows atherogenesis in mice.

Aging (Albany NY) 2019 06;11(11):3832-3850

Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada.

Elimination of senescent cells (SnC) is anti-atherogenic, but the specific contribution of senescent vascular endothelial cells (EC) is unknown. We inactivated angiopoietin like-2 (angptl2), a marker of SnEC and a pro-atherogenic cytokine in LDLr, hApoB atherosclerotic (ATX) mice. Three months after a single vascular delivery of a small hairpin (sh)Angptl2 in 3-month old ATX mice using an adeno-associated virus serotype 1 (AAV1), aortic atheroma plaque progression was slowed by 58% (p<0.0001). In the native aortic endothelium, expression was decreased by 80%, in association with a reduced expression of , a cyclin-dependent kinase inhibitor overexpressed in growth-arrested SnC. Endothelial activation was reduced (lower and expression), decreasing monocyte expression in the endothelium. One week post-injection, the ratio increased in the endothelium only, suggesting that SnEC were eliminated by apoptosis. Four weeks post-injection, the endothelial progenitor marker increased, suggesting endothelial repair. In arteries of atherosclerotic patients, we observed a strong correlation between and (r=0.727, p=0.0002) confirming the clinical significance of -associated senescence. Our data suggest that therapeutic down-regulation of vascular leads to the clearance of SnEC by apoptosis, stimulates endothelial repair and reduces atherosclerosis.
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http://dx.doi.org/10.18632/aging.102020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594793PMC
June 2019

Phosphorylation of SOCS1 Inhibits the SOCS1-p53 Tumor Suppressor Axis.

Cancer Res 2019 07 17;79(13):3306-3319. Epub 2019 May 17.

Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, Québec, Canada.

Expression of the suppressor of cytokine signaling-1 (SOCS1) is inactivated in hematopoietic and solid cancers by promoter methylation, miRNA-mediated silencing, and mutations. Paradoxically, SOCS1 is also overexpressed in many human cancers. We report here that the ability of SOCS1 to interact with p53 and regulate cellular senescence depends on a structural motif that includes tyrosine (Y)80 in the SH2 domain of SOCS1. Mutations in this motif are found at low frequency in some human cancers, and substitution of Y80 by a phosphomimetic residue inhibits p53-SOCS1 interaction and its functional consequences, including stimulation of p53 transcriptional activity, growth arrest, and cellular senescence. Mass spectrometry confirmed SOCS1 Y80 phosphorylation in cells, and a new mAb was generated to detect its presence in tissues by IHC. A tyrosine kinase library screen identified the SRC family as Y80-SOCS1 kinases. SRC family kinase inhibitors potentiated the SOCS1-p53 pathway and reinforced SOCS1-induced senescence. Samples from human lymphomas that often overexpress SOCS1 also displayed SRC family kinase activation, constitutive phosphorylation of SOCS1 on Y80, and SOCS1 cytoplasmic localization. Collectively, these results reveal a mechanism that inactivates the SOCS1-p53 senescence pathway and suggest that inhibition of SRC family kinases as personalized treatment in patients with lymphomas may be successful. SIGNIFICANCE: These findings show that SOCS1 phosphorylation by the SRC family inhibits its tumor-suppressive activity, indicating that patients with increased SOCS1 phosphorylation may benefit from SRC family kinase inhibitors.
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http://dx.doi.org/10.1158/0008-5472.CAN-18-1503DOI Listing
July 2019

Ribosomal protein RPL22/eL22 regulates the cell cycle by acting as an inhibitor of the CDK4-cyclin D complex.

Cell Cycle 2019 Mar - Apr;18(6-7):759-770. Epub 2019 Mar 28.

a Department of Biochemistry and Molecular Medicine , Université de Montréal , Montréal , Québec , Canada.

Senescence is a tumor suppressor program characterized by a stable growth arrest while maintaining cell viability. Senescence-associated ribogenesis defects (SARD) have been shown to regulate senescence through the ability of the ribosomal protein S14 (RPS14 or uS11) to bind and inhibit the cyclin-dependent kinase 4 (CDK4). Here we report another ribosomal protein that binds and inhibits CDK4 in senescent cells: L22 (RPL22 or eL22). Enforcing the expression of RPL22/eL22 is sufficient to induce an RB and p53-dependent cellular senescent phenotype in human fibroblasts. Mechanistically, RPL22/eL22 can interact with and inhibit CDK4-Cyclin D1 to decrease RB phosphorylation both in vitro and in cells. Briefly, we show that ribosome-free RPL22/eL22 causes a cell cycle arrest which could be relevant during situations of nucleolar stress such as cellular senescence or the response to cancer chemotherapy.
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http://dx.doi.org/10.1080/15384101.2019.1593708DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6464582PMC
April 2020

The senescence-associated secretory phenotype and its regulation.

Cytokine 2019 05 16;117:15-22. Epub 2019 Feb 16.

Department of Biochemistry and Molecular Medicine, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada; CRCHUM, 900 Saint-Denis - Room R10.432, Montréal, QC H2X 0A9, Canada. Electronic address:

The senescence-associated secretory phenotype (SASP) defines the ability of senescent cells to express and secrete a variety of extracellular modulators that includes cytokines, chemokines, proteases, growth factors and bioactive lipids. The role of the SASP depends on the context. The SASP reinforces the senescent cell cycle arrest, stimulates the immune-mediated clearance of potentially tumorigenic cells, limits fibrosis and promotes wound healing and tissue regeneration. On the other hand, the SASP can mediate chronic inflammation and stimulate the growth and survival of tumor cells. The regulation of the SASP occurs at multiple levels including chromatin remodelling, activation of specific transcription factors such as C/EBP and NF-κB, control of mRNA translation and intracellular trafficking. Several SASP modulators have already been identified setting the stage for future research on their clinical applications.
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http://dx.doi.org/10.1016/j.cyto.2019.01.013DOI Listing
May 2019

Ribosomal Proteins Control Tumor Suppressor Pathways in Response to Nucleolar Stress.

Bioessays 2019 03 1;41(3):e1800183. Epub 2019 Feb 1.

Department of Biochemistry and Molecular Medicine, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada.

Ribosome biogenesis includes the making and processing of ribosomal RNAs, the biosynthesis of ribosomal proteins from their mRNAs in the cytosol and their transport to the nucleolus to assemble pre-ribosomal particles. Several stresses including cellular senescence reduce nucleolar rRNA synthesis and maturation increasing the availability of ribosome-free ribosomal proteins. Several ribosomal proteins can activate the p53 tumor suppressor pathway but cells without p53 can still arrest their proliferation in response to an imbalance between ribosomal proteins and mature rRNA production. Recent results on senescence-associated ribogenesis defects (SARD) show that the ribosomal protein S14 (RPS14 or uS11) can act as a CDK4/6 inhibitor linking ribosome biogenesis defects to the main engine of cell cycle progression. This work offers new insights into the regulation of the cell cycle and suggests novel avenues to design anticancer drugs.
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http://dx.doi.org/10.1002/bies.201800183DOI Listing
March 2019

Circumventing senescence is associated with stem cell properties and metformin sensitivity.

Aging Cell 2019 04 6;18(2):e12889. Epub 2019 Jan 6.

Department of Biochemistry and Molecular Medicine and CR-CHUM, Université de Montréal, Montréal, Québec, Canada.

Most cancers arise in old individuals, which also accumulate senescent cells. Cellular senescence can be experimentally induced by expression of oncogenes or telomere shortening during serial passage in culture. In vivo, precursor lesions of several cancer types accumulate senescent cells, which are thought to represent a barrier to malignant progression and a response to the aberrant activation of growth signaling pathways by oncogenes (oncogene toxicity). Here, we sought to define gene expression changes associated with cells that bypass senescence induced by oncogenic RAS. In the context of pancreatic ductal adenocarcinoma (PDAC), oncogenic KRAS induces benign pancreatic intraepithelial neoplasias (PanINs), which exhibit features of oncogene-induced senescence. We found that the bypass of senescence in PanINs leads to malignant PDAC cells characterized by gene signatures of epithelial-mesenchymal transition, stem cells, and mitochondria. Stem cell properties were similarly acquired in PanIN cells treated with LPS, and in primary fibroblasts and mammary epithelial cells that bypassed Ras-induced senescence after reduction of ERK signaling. Intriguingly, maintenance of cells that circumvented senescence and acquired stem cell properties was blocked by metformin, an inhibitor of complex I of the electron transport chain or depletion of STAT3, a protein required for mitochondrial functions and stemness. Thus, our studies link bypass of senescence in premalignant lesions to loss of differentiation, acquisition of stemness features, and increased reliance on mitochondrial functions.
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http://dx.doi.org/10.1111/acel.12889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6413657PMC
April 2019

Molecular tools that block maturation of the nuclear lamin A and decelerate cancer cell migration.

Bioorg Med Chem 2018 11 4;26(20):5547-5554. Epub 2018 Oct 4.

Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada; Department of Biochemistry, McGill University, 3649 Promenade Sir William Osler, Montreal, QC H3G 0B1, Canada. Electronic address:

Lamin A contributes to the structure of nuclei in all mammalian cells and plays an important role in cell division and migration. Mature lamin A is derived from a farnesylated precursor protein, known as prelamin A, which undergoes post-translational cleavage catalyzed by the zinc metalloprotease STE24 (ZPMSTE24). Accumulation of farnesylated prelamin A in the nuclear envelope compromises cell division, impairs mitosis and induces an increased expression of inflammatory gene products. ZMPSTE24 has been proposed as a potential therapeutic target in oncology. A library of peptidomimetic compounds were synthesized and screened for their ability to induce accumulation of prelamin A in cancer cells and block cell migration in pancreatic ductal adenocarcinoma cells. The results of this study suggest that inhibitors of lamin A maturation may interfere with cell migration, the biological process required for cancer metastasis.
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http://dx.doi.org/10.1016/j.bmc.2018.10.001DOI Listing
November 2018

Translational and HIF-1α-Dependent Metabolic Reprogramming Underpin Metabolic Plasticity and Responses to Kinase Inhibitors and Biguanides.

Cell Metab 2018 12 20;28(6):817-832.e8. Epub 2018 Sep 20.

Lady Davis Institute, SMBD JGH, McGill University, Montreal, QC H3A 1A3, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC H3A 1A3, Canada; Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Department of Experimental Medicine, McGill University, Montreal, QC H3A 1A3, Canada. Electronic address:

There is increasing interest in therapeutically exploiting metabolic differences between normal and cancer cells. We show that kinase inhibitors (KIs) and biguanides synergistically and selectively target a variety of cancer cells. Synthesis of non-essential amino acids (NEAAs) aspartate, asparagine, and serine, as well as glutamine metabolism, are major determinants of the efficacy of KI/biguanide combinations. The mTORC1/4E-BP axis regulates aspartate, asparagine, and serine synthesis by modulating mRNA translation, while ablation of 4E-BP1/2 substantially decreases sensitivity of breast cancer and melanoma cells to KI/biguanide combinations. Efficacy of the KI/biguanide combinations is also determined by HIF-1α-dependent perturbations in glutamine metabolism, which were observed in VHL-deficient renal cancer cells. This suggests that cancer cells display metabolic plasticity by engaging non-redundant adaptive mechanisms, which allows them to survive therapeutic insults that target cancer metabolism.
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http://dx.doi.org/10.1016/j.cmet.2018.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252493PMC
December 2018

The sequence features that define efficient and specific hAGO2-dependent miRNA silencing guides.

Nucleic Acids Res 2018 09;46(16):8181-8196

Institut de recherche en immunologie et en cancérologie (IRIC), Université de Montréal, Montréal, Québec H3C 3J7, Canada.

MicroRNAs (miRNAs) are ribonucleic acids (RNAs) of ∼21 nucleotides that interfere with the translation of messenger RNAs (mRNAs) and play significant roles in development and diseases. In bilaterian animals, the specificity of miRNA targeting is determined by sequence complementarity involving the seed. However, the role of the remaining nucleotides (non-seed) is only vaguely defined, impacting negatively on our ability to efficiently use miRNAs exogenously to control gene expression. Here, using reporter assays, we deciphered the role of the base pairs formed between the non-seed region and target mRNA. We used molecular modeling to reveal that this mechanism corresponds to the formation of base pairs mediated by ordered motions of the miRNA-induced silencing complex. Subsequently, we developed an algorithm based on this distinctive recognition to predict from sequence the levels of mRNA downregulation with high accuracy (r2 > 0.5, P-value < 10-12). Overall, our discovery improves the design of miRNA-guide sequences used to simultaneously downregulate the expression of multiple predetermined target genes.
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http://dx.doi.org/10.1093/nar/gky546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6144789PMC
September 2018

Senescence-associated ribosome biogenesis defects contributes to cell cycle arrest through the Rb pathway.

Nat Cell Biol 2018 07 25;20(7):789-799. Epub 2018 Jun 25.

Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Quebec, Canada.

Cellular senescence is a tumour suppressor programme characterized by a stable cell cycle arrest. Here we report that cellular senescence triggered by a variety of stimuli leads to diminished ribosome biogenesis and the accumulation of both rRNA precursors and ribosomal proteins. These defects were associated with reduced expression of several ribosome biogenesis factors, the knockdown of which was also sufficient to induce senescence. Genetic analysis revealed that Rb but not p53 was required for the senescence response to altered ribosome biogenesis. Mechanistically, the ribosomal protein S14 (RPS14 or uS11) accumulates in the soluble non-ribosomal fraction of senescent cells, where it binds and inhibits CDK4 (cyclin-dependent kinase 4). Overexpression of RPS14 is sufficient to inhibit Rb phosphorylation, inducing cell cycle arrest and senescence. Here we describe a mechanism for maintaining the senescent cell cycle arrest that may be relevant for cancer therapy, as well as biomarkers to identify senescent cells.
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http://dx.doi.org/10.1038/s41556-018-0127-yDOI Listing
July 2018

Quantitative SUMO proteomics reveals the modulation of several PML nuclear body associated proteins and an anti-senescence function of UBC9.

Sci Rep 2018 05 17;8(1):7754. Epub 2018 May 17.

Institute of Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3C 3J7, Canada.

Several regulators of SUMOylation have been previously linked to senescence but most targets of this modification in senescent cells remain unidentified. Using a two-step purification of a modified SUMO3, we profiled the SUMO proteome of senescent cells in a site-specific manner. We identified 25 SUMO sites on 23 proteins that were significantly regulated during senescence. Of note, most of these proteins were PML nuclear body (PML-NB) associated, which correlates with the increased number and size of PML-NBs observed in senescent cells. Interestingly, the sole SUMO E2 enzyme, UBC9, was more SUMOylated during senescence on its Lys-49. Functional studies of a UBC9 mutant at Lys-49 showed a decreased association to PML-NBs and the loss of UBC9's ability to delay senescence. We thus propose both pro- and anti-senescence functions of protein SUMOylation.
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http://dx.doi.org/10.1038/s41598-018-25150-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958138PMC
May 2018

SOCS1 regulates senescence and ferroptosis by modulating the expression of p53 target genes.

Aging (Albany NY) 2017 10;9(10):2137-2162

Département de Biochimie et Médecine Moléculaire; Université de Montréal, Montréal, Québec H3C 3J7, Canada.

The mechanism by which p53 suppresses tumorigenesis remains poorly understood. In the context of aberrant activation of the JAK/STAT5 pathway, SOCS1 is required for p53 activation and the regulation of cellular senescence. In order to identify p53 target genes acting during the senescence response to oncogenic STAT5A, we characterized the transcriptome of STAT5A-expressing cells after SOCS1 inhibition. We identified a set of SOCS1-dependent p53 target genes that include several secreted proteins and genes regulating oxidative metabolism and ferroptosis. Exogenous SOCS1 was sufficient to regulate the expression of p53 target genes and sensitized cells to ferroptosis. This effect correlated with the ability of SOCS1 to reduce the expression of the cystine transporter SLC7A11 and the levels of glutathione. SOCS1 and SOCS1-dependent p53 target genes were induced during the senescence response to oncogenic STAT5A, RasV12 or the tumor suppressor PML. However, while SOCS1 sensitized cells to ferroptosis neither RasV12 nor STAT5A mimicked the effect. Intriguingly, PML turned cells highly resistant to ferroptosis. The results indicate different susceptibilities to ferroptosis in senescent cells depending on the trigger and suggest the possibility of killing senescent cells by inhibiting pathways that mediate ferroptosis resistance.
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http://dx.doi.org/10.18632/aging.101306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5680560PMC
October 2017

Aberrant signaling and senescence associated protein degradation.

Authors:
Gerardo Ferbeyre

Exp Gerontol 2018 07 27;107:50-54. Epub 2017 Jun 27.

Department of Biochemistry and Molecular Medicine, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada. Electronic address:

Senescent cells accumulate with age and contribute to pathologies associated to old age. The senescent program can be induced by pro-cancer stimuli or is developmentally controlled. In cells forced to senesce by expression of oncogenes or short telomeres, aberrant activation of the ERK/MAP kinase signaling pathway leads to selective protein degradation by the ubiquitin proteasome system. The proteins affected by this process control key cellular processes known to be defective in senescent cells. We discuss the evidence supporting a general role for aberrant signaling and senescence associated protein degradation for organismal aging.
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http://dx.doi.org/10.1016/j.exger.2017.06.016DOI Listing
July 2018

Senescence gives insights into the morphogenetic evolution of anamniotes.

Biol Open 2017 Jun 15;6(6):891-896. Epub 2017 Jun 15.

Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, Québec H3T 1J4, Canada

Senescence represents a mechanism to avoid undesired cell proliferation that plays a role in tumor suppression, wound healing and embryonic development. In order to gain insight on the evolution of senescence, we looked at its presence in developing axolotls (urodele amphibians) and in zebrafish (teleost fish), which are both anamniotes. Our data indicate that cellular senescence is present in various developing structures in axolotls (pronephros, olfactory epithelium of nerve fascicles, lateral organs, gums) and in zebrafish (epithelium of the yolk sac and in the lower part of the gut). Senescence was particularly associated with transient structures (pronephros in axolotls and yolk sac in zebrafish) suggesting that it may play a role in the elimination of these tissues. Our data supports the notion that cellular senescence evolved early in vertebrate evolution to influence embryonic development.
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http://dx.doi.org/10.1242/bio.025809DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483031PMC
June 2017

Expression of SOCS1 and the downstream targets of its putative tumor suppressor functions in prostate cancer.

BMC Cancer 2017 02 24;17(1):157. Epub 2017 Feb 24.

Department of Pediatrics, Immunology division, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Canada.

Background: Suppressor of cytokine signaling 1 (SOCS1) is considered a tumor suppressor due to frequent epigenetic and micro-RNA-mediated repression of its gene expression in diverse cancers. In prostate cancer (PCa), elevated expression of miR-30d that targets SOCS1 mRNA is associated with increased risk of disease recurrence. SOCS1 can mediate its tumor suppressor functions by diverse mechanisms such as inhibiting the JAK-STAT signaling pathway, promoting the tumor suppressor functions of p53, attenuating MET receptor tyrosine kinase signaling and blocking the oncogenic potential of the cell cycle inhibitor p21 (p21). Here, we studied the expression of SOCS1 and the downstream targets of its putative tumor suppressor functions (p53, MET and p21) in human PCa specimens to evaluate their significance as markers of disease prognosis.

Methods: Tissue microarrays were constructed of 78 archived prostatectomy specimens that were grouped according to the recommendations of the International Society of Urological Pathology (ISUP) based on the Gleason patterns. SOCS1, p53, MET and p21 protein expression were evaluated by immunohistochemical staining alongside the common prostate cancer-related markers Ki67, prostein and androgen receptor. Statistical correlations between the staining intensities of these markers and ISUP grade groups, local invasion or lymph node metastasis were evaluated.

Results: SOCS1 showed diffuse staining in the prostatic epithelium. SOCS1 staining intensity correlated inversely with the ISUP grade groups (ρ = -0.4687, p <0.0001) and Ki67 (ρ = -0.2444, p = 0.031), and positively with prostein (ρ = 0.3511, p = 0.0016). Changes in SOCS1 levels did not significantly associate with those of p53, MET or p21. However, p21 positively correlated with androgen receptor expression (ρ = -0.1388, p = 0.0003). A subset of patients with regional lymph node metastasis, although small in number, showed reduced SOCS1 expression and increased expression of MET and p21.

Conclusions: Our findings suggest that evaluating SOCS1 and p21 protein expression in prostatectomy specimens may have a prognostic value in identifying the aggressive disease. Hence, prospective studies with larger numbers of metastatic PCa specimens incorporating clinical correlates such as disease-free and overall survival are warranted.
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http://dx.doi.org/10.1186/s12885-017-3141-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5326496PMC
February 2017

Deficiency of Interleukin-15 Confers Resistance to Obesity by Diminishing Inflammation and Enhancing the Thermogenic Function of Adipose Tissues.

PLoS One 2016;11(9):e0162995. Epub 2016 Sep 29.

Division of Immunology, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, CRCHUS, Sherbrooke, Québec, Canada.

Objective: IL-15 is an inflammatory cytokine secreted by many cell types. IL-15 is also produced during physical exercise by skeletal muscle and has been reported to reduce weight gain in mice. Contrarily, our findings on IL-15 knockout (KO) mice indicate that IL-15 promotes obesity. The aim of this study is to investigate the mechanisms underlying the pro-obesity role of IL-15 in adipose tissues.

Methods: Control and IL-15 KO mice were maintained on high fat diet (HFD) or normal control diet. After 16 weeks, body weight, adipose tissue and skeletal mass, serum lipid levels and gene/protein expression in the adipose tissues were evaluated. The effect of IL-15 on thermogenesis and oxygen consumption was also studied in primary cultures of adipocytes differentiated from mouse preadipocyte and human stem cells.

Results: Our results show that IL-15 deficiency prevents diet-induced weight gain and accumulation of lipids in visceral and subcutaneous white and brown adipose tissues. Gene expression analysis also revealed elevated expression of genes associated with adaptive thermogenesis in the brown and subcutaneous adipose tissues of IL-15 KO mice. Accordingly, oxygen consumption was increased in the brown adipocytes from IL-15 KO mice. In addition, IL-15 KO mice showed decreased expression of pro-inflammatory mediators in their adipose tissues.

Conclusions: Absence of IL-15 results in decreased accumulation of fat in the white adipose tissues and increased lipid utilization via adaptive thermogenesis. IL-15 also promotes inflammation in adipose tissues that could sustain chronic inflammation leading to obesity-associated metabolic syndrome.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0162995PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042499PMC
September 2016

CDK4-CDK6 inhibitors induce autophagy-mediated degradation of DNMT1 and facilitate the senescence antitumor response.

Autophagy 2016 10 17;12(10):1965-1966. Epub 2016 Aug 17.

a Department of Biochemistry and Molecular Medicine , Université de Montréal , Montréal , Québec , Canada.

Senescence is a natural anticancer defense program disabled in tumor cells. We discovered that deregulated CDK4 (cyclin dependant kinase 4) and CDK6 activities contribute to senescence bypass during tumorigenesis and that their inhibition restores the senescence response in tumor cells. CDK4 and CDK6 phosphorylate RB1/RB, preventing its inhibitory interaction with the E2Fs, the cell cycle transcription factors. However, we also found that CDK4 interacts and phosphorylates the DNMT1 (DNA methyltransferase 1) protein protecting it from macroautophagy/autophagy-mediated protein degradation. This discovery highlights a new epigenetic component of CDK4-CDK6 signaling that could be exploited in cancer treatment.
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http://dx.doi.org/10.1080/15548627.2016.1214779DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5079664PMC
October 2016
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