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Zhong J, Xu J, Chen X, Li N, Li S, Deng Z, Feng H, Ling X, Wang C, Zhou Z, Li L. Rbm46 inhibits reactive oxygen species in mouse embryonic stem cells through modulating BNIP3-mediated mitophagy. Biochem Biophys Res Commun 2024; 708:149779. [PMID: 38518724 DOI: 10.1016/j.bbrc.2024.149779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/29/2024] [Accepted: 03/11/2024] [Indexed: 03/24/2024]
Abstract
Embryonic stem cells (ESCs) exhibit a metabolic preference for glycolysis over oxidative phosphorylation to meet their substantial adenosine triphosphate (ATP) demands during self-renewal. This metabolic choice inherently maintains low mitochondrial activity and minimal reactive oxygen species (ROS) generation. Nonetheless, the intricate molecular mechanisms governing the restraint of ROS production and the mitigation of cellular damage remain incompletely elucidated. In this study, we reveal the pivotal role of RNA-binding motif protein 46 (RBM46) in ESCs, acting as a direct post transcriptional regulator of ROS levels by modulating BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (Bnip3) mRNA expression. Rbm46 knockout lead to diminished mitochondrial autophagy, culminating in elevated ROS within ESCs, disrupting the delicate balance required for healthy self-renewal. These findings provide insights into a novel mechanism governing ROS regulation in ESCs.
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Affiliation(s)
- Jinchen Zhong
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jing Xu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xiaoyang Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Na Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Sha Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Zhiwen Deng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Huimin Feng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xiaohan Ling
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chenchen Wang
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China.
| | - Zhi Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
| | - Lingsong Li
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China.
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2
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Rouf MA, Wen L, Mahendra Y, Wang J, Zhang K, Liang S, Wang Y, Li Z, Wang Y, Wang G. The recent advances and future perspectives of genetic compensation studies in the zebrafish model. Genes Dis 2022; 10:468-479. [DOI: 10.1016/j.gendis.2021.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 10/19/2022] Open
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3
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A Gene Signature Derived from the Loss of CDKN1A (p21) Is Associated with CMS4 Colorectal Cancer. Cancers (Basel) 2021; 14:cancers14010136. [PMID: 35008299 PMCID: PMC8750372 DOI: 10.3390/cancers14010136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/14/2021] [Accepted: 12/20/2021] [Indexed: 12/02/2022] Open
Abstract
Simple Summary A gene signature derived from the loss of CDKN1A (p21) gene, obtained in HCT116 p21-/- colorectal cancer cells, is identified in a large cohort of primary colorectal (CRC) tumors and is associated with the Consensus Molecular Subtype (CMS) of colon cancer that has a worse relapse-free and overall survival, that is, CMS4 (also called mesenchymal subtype). The presented gene signature can help to uncover the early molecular mechanisms of epithelial–mesenchymal transition (EMT), which is known to be associated with high stemness and drug resistance. Abstract The epithelial–mesenchymal transition (EMT) is associated with tumor aggressiveness and increased invasion, migration, metastasis, angiogenesis, and drug resistance. Although the HCT116 p21-/- cell line is well known for its EMT-associated phenotype, with high Vimentin and low E-cadherin protein levels, the gene signature of this rather intermediate EMT-like cell line has not been determined so far. In this work, we present a robust molecular and bioinformatics analysis, to reveal the associated gene expression profile and its correlation with different types of colorectal cancer tumors. We compared the quantitative signature obtained with the NanoString platform with the expression profiles of colorectal cancer (CRC) Consensus Molecular Subtypes (CMS) as identified, and validated the results in a large independent cohort of human tumor samples. The expression signature derived from the p21-/- cells showed consistent and reliable numbers of upregulated and downregulated genes, as evaluated with two machine learning methods against the four CRC subtypes (i.e., CMS1, 2, 3, and 4). High concordance was found between the upregulated gene signature of HCT116 p21-/- cells and the signature of the CMS4 mesenchymal subtype. At the same time, the upregulated gene signature of the native HCT116 cells was similar to that of CMS1. Using a multivariate Cox regression model to analyze the survival data in the CRC tumor cohort, we selected genes that have a predictive risk power (with a significant gene risk incidence score). A set of genes of the mesenchymal signature was proven to be significantly associated with poor survival, specifically in the CMS4 CRC human cohort. We suggest that the gene signature of HCT116 p21-/- cells could be a suitable metric for mechanistic studies regarding the CMS4 signature and its functional consequences in CRC. Moreover, this model could help to discover the molecular mechanisms of intermediate EMT, which is known to be associated with extraordinarily high stemness and drug resistance.
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4
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Wang K, Chen H, Zhou Z, Zhang H, Zhou HJ, Min W. ATPIF1 maintains normal mitochondrial structure which is impaired by CCM3 deficiency in endothelial cells. Cell Biosci 2021; 11:11. [PMID: 33422124 PMCID: PMC7796565 DOI: 10.1186/s13578-020-00514-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/07/2020] [Indexed: 01/01/2023] Open
Abstract
Background Numerous signaling pathways have been demonstrated experimentally to affect the pathogenesis of cerebral cavernous malformations (CCM), a disease that can be caused by CCM3 deficiency. However, the understanding of the CCM progression is still limited. The objective of the present work was to elucidate the role of CCM3 by RNA-seq screening of CCM3 knockout mice. Results We found that ATPIF1 was decreased in siCCM3-treated Human Umbilical Vein Endothelial Cells (HUVECs), and the overexpression of ATPIF1 attenuated the changes in cell proliferation, adhesion and migration caused by siCCM3. The probable mechanism involved the conserved ATP concentration in mitochondria and the elongated morphology of the organelles. By using the CRISPR-cas9 system, we generated CCM3-KO Endothelial Progenitor Cells (EPCs) and found that the knockout of CCM3 destroyed the morphology of mitochondria, impaired the mitochondrial membrane potential and increased mitophagy. Overexpression of ATPIF1 contributed to the maintenance of normal structure of mitochondria, inhibiting activation of mitophagy and other signaling proteins (e.g., KLF4 and Tie2). The expression of KLF4 returned to normal in CCM3-KO EPCs after 2 days of re-overexpression of CCM3, but not other signaling proteins. Conclusion ATPIF1 maintains the normal structure of mitochondria, inhibiting the activation of mitophagy and other signaling pathway in endothelial cells. Loss of CCM3 leads to the destruction of mitochondria and activation of signaling pathways, which can be regulated by KLF4.
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Affiliation(s)
- Kang Wang
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China.,Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Haixuan Chen
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Zhongyang Zhou
- Center for Translational Medicine, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Haifeng Zhang
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Huanjiao Jenny Zhou
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, CT, 06520, USA.
| | - Wang Min
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, CT, 06520, USA.
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5
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Bare DJ, Cherny VV, DeCoursey TE, Abukhdeir AM, Morgan D. Expression and function of voltage gated proton channels (Hv1) in MDA-MB-231 cells. PLoS One 2020; 15:e0227522. [PMID: 32374759 PMCID: PMC7202653 DOI: 10.1371/journal.pone.0227522] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 04/09/2020] [Indexed: 02/07/2023] Open
Abstract
Expression of the voltage gated proton channel (Hv1) as identified by immunocytochemistry has been reported previously in breast cancer tissue. Increased expression of HV1 was correlated with poor prognosis and decreased overall and disease-free survival but the mechanism of its involvement in the disease is unknown. Here we present electrophysiological recordings of HV1 channel activity, confirming its presence and function in the plasma membrane of a breast cancer cell line, MDA-MB-231. With western blotting we identify significant levels of HV1 expression in 3 out of 8 “triple negative” breast cancer cell lines (estrogen, progesterone, and HER2 receptor expression negative). We examine the function of HV1 in breast cancer using MDA-MB-231 cells as a model by suppressing the expression of HV1 using shRNA (knock-down; KD) and by eliminating HV1 using CRISPR/Cas9 gene editing (knock-out; KO). Surprisingly, these two approaches produced incongruous effects. Knock-down of HV1 using shRNA resulted in slower cell migration in a scratch assay and a significant reduction in H2O2 release. In contrast, HV1 Knock-out cells did not show reduced migration or H2O2 release. HV1 KO but not KD cells showed an increased glycolytic rate accompanied by an increase in p-AKT (phospho-AKT, Ser473) activity. The expression of CD171/LCAM-1, an adhesion molecule and prognostic indicator for breast cancer, was reduced in HV1 KO cells. When we compared MDA-MB-231 xenograft growth rates in immunocompromised mice, tumors from HV1 KO cells grew less than WT in mass, with lower staining for the Ki-67 marker for cell proliferation rate. Therefore, deletion of HV1 expression in MDA-MB-231 cells limits tumor growth rate. The limited growth thus appears to be independent of oxidant production by NADPH oxidase molecules and to be mediated by cell adhesion molecules. Although HV1 KO and KD affect certain cellular mechanisms differently, both implicate HV1-mediated pathways for control of tumor growth in the MDA-MB-231 cell line.
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Affiliation(s)
- Dan J Bare
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Vladimir V Cherny
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Abde M Abukhdeir
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States of America
| | - Deri Morgan
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, MO, United States of America
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6
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Grotz AK, Abaitua F, Navarro-Guerrero E, Hastoy B, Ebner D, Gloyn AL. A CRISPR/Cas9 genome editing pipeline in the EndoC-βH1 cell line to study genes implicated in beta cell function. Wellcome Open Res 2020; 4:150. [PMID: 31976379 PMCID: PMC6961417 DOI: 10.12688/wellcomeopenres.15447.2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2020] [Indexed: 12/30/2022] Open
Abstract
Type 2 diabetes (T2D) is a global pandemic with a strong genetic component, but most causal genes influencing the disease risk remain unknown. It is clear, however, that the pancreatic beta cell is central to T2D pathogenesis. In vitro gene-knockout (KO) models to study T2D risk genes have so far focused on rodent beta cells. However, there are important structural and functional differences between rodent and human beta cell lines. With that in mind, we have developed a robust pipeline to create a stable CRISPR/Cas9 KO in an authentic human beta cell line (EndoC-βH1). The KO pipeline consists of a dual lentiviral sgRNA strategy and we targeted three genes ( INS, IDE, PAM) as a proof of concept. We achieved a significant reduction in mRNA levels and complete protein depletion of all target genes. Using this dual sgRNA strategy, up to 94 kb DNA were cut out of the target genes and the editing efficiency of each sgRNA exceeded >87.5%. Sequencing of off-targets showed no unspecific editing. Most importantly, the pipeline did not affect the glucose-responsive insulin secretion of the cells. Interestingly, comparison of KO cell lines for NEUROD1 and SLC30A8 with siRNA-mediated knockdown (KD) approaches demonstrate phenotypic differences. NEUROD1-KO cells were not viable and displayed elevated markers for ER stress and apoptosis. NEUROD1-KD, however, only had a modest elevation, by 34%, in the pro-apoptotic transcription factor CHOP and a gene expression profile indicative of chronic ER stress without evidence of elevated cell death. On the other hand, SLC30A8-KO cells demonstrated no reduction in K ATP channel gene expression in contrast to siRNA silencing. Overall, this strategy to efficiently create stable KO in the human beta cell line EndoC-βH1 will allow for a better understanding of genes involved in beta cell dysfunction, their underlying functional mechanisms and T2D pathogenesis.
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Affiliation(s)
- Antje K. Grotz
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
| | - Fernando Abaitua
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | | | - Benoit Hastoy
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
| | - Daniel Ebner
- Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Anna L. Gloyn
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Churchill Hospital, Oxford, OX3 7LE, UK
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7
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Genetic compensation in a stable slc25a46 mutant zebrafish: A case for using F0 CRISPR mutagenesis to study phenotypes caused by inherited disease. PLoS One 2020; 15:e0230566. [PMID: 32208444 PMCID: PMC7092968 DOI: 10.1371/journal.pone.0230566] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 03/03/2020] [Indexed: 12/22/2022] Open
Abstract
A phenomenon of genetic compensation is commonly observed when an organism with a disease-bearing mutation shows incomplete penetrance of the disease phenotype. Such incomplete phenotypic penetrance, or genetic compensation, is more commonly found in stable knockout models, rather than transient knockdown models. As such, these incidents present a challenge for the disease modeling field, although a deeper understanding of genetic compensation may also hold the key for novel therapeutic interventions. In our study we created a knockout model of slc25a46 gene, which is a recently discovered important player in mitochondrial dynamics, and deleterious mutations in which are known to cause peripheral neuropathy, optic atrophy and cerebellar ataxia. We report a case of genetic compensation in a stable slc25a46 homozygous zebrafish mutant (hereafter referred as “mutant”), in contrast to a penetrant disease phenotype in the first generation (F0) slc25a46 mosaic mutant (hereafter referred as “crispant”), generated with CRISPR/Cas-9 technology. We show that the crispant phenotype is specific and rescuable. By performing mRNA sequencing, we define significant changes in slc25a46 mutant’s gene expression profile, which are largely absent in crispants. We find that among the most significantly altered mRNAs, anxa6 gene stands out as a functionally relevant player in mitochondrial dynamics. We also find that our genetic compensation case does not arise from mechanisms driven by mutant mRNA decay. Our study contributes to the growing evidence of the genetic compensation phenomenon and presents novel insights about Slc25a46 function. Furthermore, our study provides the evidence for the efficiency of F0 CRISPR screens for disease candidate genes, which may be used to advance the field of functional genetics.
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8
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Grotz AK, Abaitua F, Navarro-Guerrero E, Hastoy B, Ebner D, Gloyn AL. A CRISPR/Cas9 genome editing pipeline in the EndoC-βH1 cell line to study genes implicated in beta cell function. Wellcome Open Res 2019; 4:150. [PMID: 31976379 PMCID: PMC6961417 DOI: 10.12688/wellcomeopenres.15447.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2019] [Indexed: 12/30/2022] Open
Abstract
Type 2 diabetes (T2D) is a global pandemic with a strong genetic component, but most causal genes influencing the disease risk remain unknown. It is clear, however, that the pancreatic beta cell is central to T2D pathogenesis. In vitro gene-knockout (KO) models to study T2D risk genes have so far focused on rodent beta cells. However, there are important structural and functional differences between rodent and human beta cell lines. With that in mind, we have developed a robust pipeline to create a stable CRISPR/Cas9 KO in an authentic human beta cell line (EndoC-βH1). The KO pipeline consists of a dual lentiviral sgRNA strategy and we targeted three genes ( INS, IDE, PAM) as a proof of concept. We achieved a significant reduction in mRNA levels and complete protein depletion of all target genes. Using this dual sgRNA strategy, up to 94 kb DNA were cut out of the target genes and the editing efficiency of each sgRNA exceeded >87.5%. Sequencing of off-targets showed no unspecific editing. Most importantly, the pipeline did not affect the glucose-responsive insulin secretion of the cells. Interestingly, comparison of KO cell lines for NEUROD1 and SLC30A8 with siRNA-mediated knockdown (KD) approaches demonstrate phenotypic differences. NEUROD1-KO cells were not viable and displayed elevated markers for ER stress and apoptosis. NEUROD1-KD, however, only had a modest elevation, by 34%, in the pro-apoptotic transcription factor CHOP and a gene expression profile indicative of chronic ER stress without evidence of elevated cell death. On the other hand, SLC30A8-KO cells demonstrated no reduction in K ATP channel gene expression in contrast to siRNA silencing. Overall, this strategy to efficiently create stable KO in the human beta cell line EndoC-βH1 will allow for a better understanding of genes involved in beta cell dysfunction, their underlying functional mechanisms and T2D pathogenesis.
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Affiliation(s)
- Antje K. Grotz
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
| | - Fernando Abaitua
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | | | - Benoit Hastoy
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
| | - Daniel Ebner
- Target Discovery Institute, University of Oxford, Oxford, OX3 7FZ, UK
| | - Anna L. Gloyn
- Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, OX3 7LE, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Churchill Hospital, Oxford, OX3 7LE, UK
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9
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Kim YA, Moon H, Park CJ. CRISPR/Cas9-targeted mutagenesis of Os8N3 in rice to confer resistance to Xanthomonas oryzae pv. oryzae. RICE (NEW YORK, N.Y.) 2019; 12:67. [PMID: 31446506 PMCID: PMC6708514 DOI: 10.1186/s12284-019-0325-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/13/2019] [Indexed: 05/05/2023]
Abstract
BACKGROUND Genome editing tools are important for functional genomics research and biotechnology applications. Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) system for gene knockout has emerged as the most effective genome-editing tool. It has previously been reported that, in rice plants, knockdown of the Os8N3 gene resulted in enhanced resistance to Xanthomonas oryzae pv. oryzae (Xoo), while displaying abnormal pollen development. RESULTS The CRISPR/Cas9 system was employed to knockout rice Os8N3, in order to confer enhanced resistance to Xoo. Analysis of the genotypes and edited Os8N3 in T0, T1, T2, and T3 transgenic rice plants showed that the mutations were transmitted to subsequent generations, and homozygous mutants displayed significantly enhanced resistance to Xoo. Stable transmission of CRISPR/Cas9-mediated Os8N3 gene editing without the transferred DNA (T-DNA) was confirmed by segregation in the T1 generation. With respect to many investigated agronomic traits including pollen development, there was no significant difference between homozygous mutants and non-transgenic control plants under greenhouse growth conditions. CONCLUSION Data from this study indicate that the CRISPR/Cas9-mediated Os8N3 edition can be successfully employed for non-transgenic crop improvements.
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Affiliation(s)
- Young-Ah Kim
- Department of Plant Biotechnology, Sejong University, Seoul, 05006 South Korea
| | - Hyeran Moon
- Department of Molecular Biology, Sejong University, Seoul, 05006 South Korea
| | - Chang-Jin Park
- Department of Plant Biotechnology, Sejong University, Seoul, 05006 South Korea
- Department of Molecular Biology, Sejong University, Seoul, 05006 South Korea
- Plant Engineering Research Institute, Sejong University, Seoul, 05006 South Korea
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10
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Brachs S, Polack J, Brachs M, Jahn-Hofmann K, Elvert R, Pfenninger A, Bärenz F, Margerie D, Mai K, Spranger J, Kannt A. Genetic Nicotinamide N-Methyltransferase ( Nnmt) Deficiency in Male Mice Improves Insulin Sensitivity in Diet-Induced Obesity but Does Not Affect Glucose Tolerance. Diabetes 2019; 68:527-542. [PMID: 30552109 DOI: 10.2337/db18-0780] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 12/03/2018] [Indexed: 11/13/2022]
Abstract
Antisense oligonucleotide knockdown (ASO-KD) of nicotinamide N-methyltransferase (NNMT) in high-fat diet (HFD)-fed mice has been reported to reduce weight gain and plasma insulin levels and to improve glucose tolerance. Using NNMT-ASO-KD or NNMT knockout mice (NNMT-/-), we tested the hypothesis that Nnmt deletion protects against diet-induced obesity and its metabolic consequences in males and females on obesity-inducing diets. We also examined samples from a human weight reduction (WR) study for adipose NNMT (aNNMT) expression and plasma 1-methylnicotinamide (MNAM) levels. In Western diet (WD)-fed female mice, NNMT-ASO-KD reduced body weight, fat mass, and insulin level and improved glucose tolerance. Although NNMT-/- mice fed a standard diet had no obvious phenotype, NNMT-/- males fed an HFD showed strongly improved insulin sensitivity (IS). Furthermore, NNMT-/- females fed a WD showed reduced weight gain, less fat, and lower insulin levels. However, no improved glucose tolerance was observed in NNMT-/- mice. Although NNMT expression in human fat biopsy samples increased during WR, corresponding plasma MNAM levels significantly declined, suggesting that other mechanisms besides aNNMT expression modulate circulating MNAM levels during WR. In summary, upon NNMT deletion or knockdown in males and females fed different obesity-inducing diets, we observed sex- and diet-specific differences in body composition, weight, and glucose tolerance and estimates of IS.
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Affiliation(s)
- Sebastian Brachs
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
- Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - James Polack
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
- Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Maria Brachs
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Ralf Elvert
- Sanofi Research and Development, Frankfurt am Main, Germany
| | | | - Felix Bärenz
- Sanofi Research and Development, Frankfurt am Main, Germany
| | | | - Knut Mai
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
- Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
- Clinical Research Unit, Berlin Institute of Health (BIH), Berlin, Germany
| | - Joachim Spranger
- Department of Endocrinology and Metabolism, Charité-Universitätsmedizin Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
- Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
- Clinical Research Unit, Berlin Institute of Health (BIH), Berlin, Germany
| | - Aimo Kannt
- Sanofi Research and Development, Frankfurt am Main, Germany
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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11
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Combined shRNA over CRISPR/cas9 as a methodology to detect off-target effects and a potential compensatory mechanism. Sci Rep 2018; 8:93. [PMID: 29311693 PMCID: PMC5758708 DOI: 10.1038/s41598-017-18551-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 12/13/2017] [Indexed: 11/25/2022] Open
Abstract
Inhibition of genes is a powerful approach to study their function. While RNA interference is a widely used method to achieve this goal, mounting evidence indicates that such an approach is prone to off-target effects. An alternative approach to gene function inhibition is genetic mutation, such as the CRISPR/cas9 method. A recent report, however, demonstrated that genetic mutation and inhibition of gene expression do not always give corresponding results. This can be explained by off-target effects, but it was recently shown, at least in one case, that these differences are the result of a compensatory mechanism induced only by genetic mutation. We present here a combination of RNA inhibition and CRISPR/cas9 methods to identify possible off targets as well as potential compensatory effects. This approach is demonstrated by testing a possible role for Sema4B in glioma biology, in which our results implicate Sema4B as having a critical function. In stark contrast, by using shRNA over CRISPR/cas9 combined methodology, we clearly demonstrate that the Sema4B targeted shRNA effects on cell proliferation is the result of off-target effects. Nevertheless, it also revealed that certain splice variants of Sema4B are important for the ability of glioma cells to grow as individual clones.
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12
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Gustin JP, Miller J, Farag M, Rosen DM, Thomas M, Scharpf RB, Lauring J. GATA3 frameshift mutation promotes tumor growth in human luminal breast cancer cells and induces transcriptional changes seen in primary GATA3 mutant breast cancers. Oncotarget 2017; 8:103415-103427. [PMID: 29262572 PMCID: PMC5732738 DOI: 10.18632/oncotarget.21910] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 10/10/2017] [Indexed: 12/29/2022] Open
Abstract
The GATA3 transcription factor is one of the most frequently mutated genes in breast cancer. Heterozygous mutations, mostly frameshifts, are seen in 15% of estrogen receptor positive breast cancers, the subtype in which these mutations are almost exclusively found. Mouse studies have shown that Gata3 is critical for breast development and that GATA3 gene dosage affects breast tumor progression. Human patient data have shown that high Gata3 expression, a feature of luminal subtype breast cancers, is associated with a better prognosis. Although the frequency of GATA3 mutation suggests an important role in breast cancer development or progression, there is little understanding of how mutations in GATA3 affect its function in luminal breast epithelial cells and what gene expression changes result as a consequence of the mutations. Here, using gene editing, we have created two sets of isogenic human luminal breast cancer cell lines with and without a hotspot truncating GATA3 mutation. GATA3 mutation enhanced tumor growth in vivo but did not affect sensitivity to clinically used hormonal therapies or chemotherapeutic agents. We identified genes with upregulated and downregulated expression in GATA3 mutant cells, a subset of which was concordantly differentially expressed in GATA3 mutant primary luminal breast cancers. Addback of mutant GATA3 recapitulated mutation-specific gene expression changes and enhanced soft agar colony formation, suggesting a gain of function for the mutant protein.
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Affiliation(s)
- John P Gustin
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Jernelle Miller
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Mina Farag
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - D Marc Rosen
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Matthew Thomas
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Robert B Scharpf
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - Josh Lauring
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
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13
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Abstract
Several recent studies in a number of model systems including zebrafish, Arabidopsis, and mouse have revealed phenotypic differences between knockouts (i.e., mutants) and knockdowns (e.g., antisense-treated animals). These differences have been attributed to a number of reasons including off-target effects of the antisense reagents. An alternative explanation was recently proposed based on a zebrafish study reporting that genetic compensation was observed in egfl7 mutant but not knockdown animals. Dosage compensation was first reported in Drosophila in 1932, and genetic compensation in response to a gene knockout was first reported in yeast in 1969. Since then, genetic compensation has been documented many times in a number of model organisms; however, our understanding of the underlying molecular mechanisms remains limited. In this review, we revisit studies reporting genetic compensation in higher eukaryotes and outline possible molecular mechanisms, which may include both transcriptional and posttranscriptional processes.
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Affiliation(s)
- Mohamed A. El-Brolosy
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Didier Y. R. Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
- * E-mail:
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14
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Cidado J, Wong HY, Rosen DM, Cimino-Mathews A, Garay JP, Fessler AG, Rasheed ZA, Hicks J, Cochran RL, Croessmann S, Zabransky DJ, Mohseni M, Beaver JA, Chu D, Cravero K, Christenson ES, Medford A, Mattox A, De Marzo AM, Argani P, Chawla A, Hurley PJ, Lauring J, Park BH. Ki-67 is required for maintenance of cancer stem cells but not cell proliferation. Oncotarget 2017; 7:6281-93. [PMID: 26823390 PMCID: PMC4868756 DOI: 10.18632/oncotarget.7057] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/05/2016] [Indexed: 01/08/2023] Open
Abstract
Ki-67 expression is correlated with cell proliferation and is a prognostic marker for various cancers; however, its function is unknown. Here we demonstrate that genetic disruption of Ki-67 in human epithelial breast and colon cancer cells depletes the cancer stem cell niche. Ki-67 null cells had a proliferative disadvantage compared to wildtype controls in colony formation assays and displayed increased sensitivity to various chemotherapies. Ki-67 null cancer cells showed decreased and delayed tumor formation in xenograft assays, which was associated with a reduction in cancer stem cell markers. Immunohistochemical analyses of human breast cancers revealed that Ki-67 expression is maintained at equivalent or greater levels in metastatic sites of disease compared to matched primary tumors, suggesting that maintenance of Ki-67 expression is associated with metastatic/clonogenic potential. These results elucidate Ki-67's role in maintaining the cancer stem cell niche, which has potential diagnostic and therapeutic implications for human malignancies.
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Affiliation(s)
- Justin Cidado
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Present address: Oncology iMED, AstraZeneca, Waltham, MA, USA
| | - Hong Yuen Wong
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - D Marc Rosen
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ashley Cimino-Mathews
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Joseph P Garay
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Abigail G Fessler
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zeshaan A Rasheed
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jessica Hicks
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rory L Cochran
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sarah Croessmann
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel J Zabransky
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Morassa Mohseni
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Present address: Roche Sequencing, San Jose, CA, USA
| | - Julia A Beaver
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David Chu
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Karen Cravero
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Eric S Christenson
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Arielle Medford
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Austin Mattox
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Angelo M De Marzo
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Pedram Argani
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ajay Chawla
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA.,Departments of Physiology and Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Paula J Hurley
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Josh Lauring
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ben Ho Park
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.,The Whiting School of Engineering, Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA
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15
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Thomas SP, Kim E, Kim JS, Raines RT. Knockout of the Ribonuclease Inhibitor Gene Leaves Human Cells Vulnerable to Secretory Ribonucleases. Biochemistry 2016; 55:6359-6362. [PMID: 27806571 DOI: 10.1021/acs.biochem.6b01003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ribonuclease inhibitor (RNH1) is a cytosolic protein that binds with femtomolar affinity to human ribonuclease 1 (RNase 1) and homologous secretory ribonucleases. RNH1 contains 32 cysteine residues and has been implicated as an antioxidant. Here, we use CRISPR-Cas9 to knock out RNH1 in HeLa cells. We find that cellular RNH1 affords marked protection from the lethal ribonucleolytic activity of RNase 1 but not from oxidants. We conclude that RNH1 protects cytosolic RNA from invading ribonucleases.
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Affiliation(s)
- Sydney P Thomas
- Graduate Program in Cellular & Molecular Biology, University of Wisconsin-Madison , 1525 Linden Drive, Madison, Wisconsin 53706, United States
| | - Eunji Kim
- Center for Genome Engineering, Institute for Basic Science , Seoul 08826, Republic of Korea
| | - Jin-Soo Kim
- Center for Genome Engineering, Institute for Basic Science , Seoul 08826, Republic of Korea
| | - Ronald T Raines
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States
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16
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Blair BG, Wu X, Zahari MS, Mohseni M, Cidado J, Wong HY, Beaver JA, Cochran RL, Zabransky DJ, Croessmann S, Chu D, Toro PV, Cravero K, Pandey A, Park BH. A phosphoproteomic screen demonstrates differential dependence on HER3 for MAP kinase pathway activation by distinct PIK3CA mutations. Proteomics 2014; 15:318-26. [PMID: 25367220 DOI: 10.1002/pmic.201400342] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/02/2014] [Accepted: 10/29/2014] [Indexed: 11/07/2022]
Abstract
The PIK3CA gene encodes for the p110 alpha isoform of PI3 kinase and is one of the most frequently mutated oncogenes in human cancers. However, the mechanisms by which PIK3CA mutations activate cell signaling are not fully understood. Here we used a phosphoproteomic approach to compare differential phosphorylation patterns between human breast epithelial cells and two isogenic somatic cell knock in derivatives, each harboring a distinct PIK3CA mutation. We demonstrated differential phosphorylation patterns between isogenic cell lines containing a PIK3CA helical domain mutation (E545K) compared to cells with a PIK3CA kinase domain mutation (H1047R). In particular, the receptor tyrosine kinase, HER3, showed increased phosphorylation at tyrosine 1328 in H1047R cells versus E545K cells. Genetic studies using shRNA demonstrated that H1047R cells have a profound decrease in growth factor independent proliferation upon HER3 knock down, but this effect was attenuated in E545K cells. In addition, HER3 knock down led to reductions in both PI3 kinase and MAP kinase pathway activation in H1047R cells, but in E545K cells only PI3 kinase pathway diminution was observed. These studies demonstrate the power of using paired isogenic cell lines for proteomic analysis to gain new insights into oncogenic signal transduction pathways.
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Affiliation(s)
- Brian G Blair
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University School of Medicine, Baltimore, MD, USA
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17
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Harris DR, Mims A, Bunz F. Genetic disruption of USP9X sensitizes colorectal cancer cells to 5-fluorouracil. Cancer Biol Ther 2012; 13:1319-24. [PMID: 22895071 DOI: 10.4161/cbt.21792] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The X-linked deubiquitinase USP9X affects the stability and activity of numerous regulatory proteins that influence cell survival. Recent studies suggest that decreased USP9X expression can confer a selective advantage onto developing cancer cells and thereby promotes disease progression. To examine the effect of USP9X on the cellular responses to anticancer therapies, we derived cancer cell lines in which the USP9X locus was disrupted by homologous recombination. The resulting USP9X-deficient cancer cells exhibited increased activation of apoptotic pathways and markedly decreased clonogenic survival in response to 5-fluorouracil, a chemotherapeutic drug that is widely used for treatment of gastrointestinal malignancies. These unexpected results suggest that cancers with low USP9X expression might be specifically sensitized to some conventional therapeutic agents.
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Affiliation(s)
- Dennis R Harris
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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18
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Garay JP, Karakas B, Abukhdeir AM, Cosgrove DP, Gustin JP, Higgins MJ, Konishi H, Konishi Y, Lauring J, Mohseni M, Wang GM, Jelovac D, Weeraratna A, Sherman Baust CA, Morin PJ, Toubaji A, Meeker A, De Marzo AM, Lewis G, Subhawong A, Argani P, Park BH. The growth response to androgen receptor signaling in ERα-negative human breast cells is dependent on p21 and mediated by MAPK activation. Breast Cancer Res 2012; 14:R27. [PMID: 22321971 PMCID: PMC3496145 DOI: 10.1186/bcr3112] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 09/27/2011] [Accepted: 02/09/2012] [Indexed: 01/02/2023] Open
Abstract
Introduction Although a high frequency of androgen receptor (AR) expression in human breast cancers has been described, exploiting this knowledge for therapy has been challenging. This is in part because androgens can either inhibit or stimulate cell proliferation in pre-clinical models of breast cancer. In addition, many breast cancers co-express other steroid hormone receptors that can affect AR signaling, further obfuscating the effects of androgens on breast cancer cells. Methods To create better-defined models of AR signaling in human breast epithelial cells, we took estrogen receptor (ER)-α-negative and progesterone receptor (PR)-negative human breast epithelial cell lines, both cancerous and non-cancerous, and engineered them to express AR, thus allowing the unambiguous study of AR signaling. We cloned a full-length cDNA of human AR, and expressed this transgene in MCF-10A non-tumorigenic human breast epithelial cells and MDA-MB-231 human breast-cancer cells. We characterized the responses to AR ligand binding using various assays, and used isogenic MCF-10A p21 knock-out cell lines expressing AR to demonstrate the requirement for p21 in mediating the proliferative responses to AR signaling in human breast epithelial cells. Results We found that hyperactivation of the mitogen-activated protein kinase (MAPK) pathway from both AR and epidermal growth factor receptor (EGFR) signaling resulted in a growth-inhibitory response, whereas MAPK signaling from either AR or EGFR activation resulted in cellular proliferation. Additionally, p21 gene knock-out studies confirmed that AR signaling/activation of the MAPK pathway is dependent on p21. Conclusions These studies present a new model for the analysis of AR signaling in human breast epithelial cells lacking ERα/PR expression, providing an experimental system without the potential confounding effects of ERα/PR crosstalk. Using this system, we provide a mechanistic explanation for previous observations ascribing a dual role for AR signaling in human breast cancer cells. As previous reports have shown that approximately 40% of breast cancers can lack p21 expression, our data also identify potential new caveats for exploiting AR as a target for breast cancer therapy.
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Affiliation(s)
- Joseph P Garay
- The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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19
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Achuthan S, Santhoshkumar TR, Prabhakar J, Nair SA, Pillai MR. Drug-induced senescence generates chemoresistant stemlike cells with low reactive oxygen species. J Biol Chem 2011; 286:37813-29. [PMID: 21878644 PMCID: PMC3199523 DOI: 10.1074/jbc.m110.200675] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Tumor recurrence after chemotherapy or radiation remains a major obstacle to successful cancer treatment. A subset of cancer cells, termed cancer stem cells, can elude conventional treatments and eventually regenerate a tumor that is more aggressive. Despite the large number of studies, molecular events that govern the emergence of aggressive therapy-resistant cells with stem cell properties after chemotherapy are poorly defined. The present study provides evidence for the rare escape of tumor cells from drug-induced cell death, after an intermediate stay in a non-cycling senescent stage followed by unstable multiplication characterized by spontaneous cell death. However, some cells appear to escape and generate stable colonies with an aggressive tumor stem cell-like phenotype. These cells displayed higher CD133 and Oct-4 expression. Notably, the drug-selected cells that contained low levels of reactive oxygen species (ROS) also showed an increase in antioxidant enzymes. Consistent with this in vitro experimental data, we observed lower levels of ROS in breast tumors obtained after neoadjuvant chemotherapy compared with samples that did not receive preoperative chemotherapy. These latter tissues also expressed enhanced levels of ROS defenses with enhanced expression of superoxide dismutase. Higher levels of Oct-4 and CD133 were also observed in tumors obtained after neoadjuvant chemotherapy. Further studies provided evidence for the stabilization of Nrf2 due to reduced 26 S proteasome activity and increased p21 association as the driving signaling event that contributes to the transition from a high ROS quiescent state to a low ROS proliferating stage in drug-induced tumor stem cell enrichment.
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Affiliation(s)
- Santhi Achuthan
- Cancer Research Program, Rajiv Gandhi Centre for Biotechnology, Thycaud, Thiruvananthapuram 695014, Kerala, India
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20
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Andorfer P, Rotheneder H. EAPP: gatekeeper at the crossroad of apoptosis and p21-mediated cell-cycle arrest. Oncogene 2011; 30:2679-90. [PMID: 21258403 PMCID: PMC3114185 DOI: 10.1038/onc.2010.639] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We previously identified and characterized E2F-associated phospho-protein (EAPP), a nuclear phosphoprotein that interacts with the activating members of the E2F transcription factor family. EAPP levels are frequently elevated in transformed human cells. To examine the biological relevance of EAPP, we studied its properties in stressed and unstressed cells. Overexpression of EAPP in U2OS cells increased the fraction of G1 cells and lead to heightened resistance against DNA damage- or E2F1-induced apoptosis in a p21-dependent manner. EAPP itself becomes upregulated in confluent cells and after DNA damage and stimulates the expression of p21 independently of p53. It binds to the p21 promoter and seems to be required for the assembly of the transcription initiation complex. RNAi-mediated knockdown of EAPP expression brought about increased sensitivity towards DNA damage and resulted in apoptosis even in the absence of stress. Our results indicate that the level of EAPP is critical for cellular homeostasis. Too much of it results in G1 arrest and resistance to apoptosis, which, paradoxically, might favor cellular transformation. Too little EAPP seems to retard the expression not only of the p21 gene, but also of a number of other genes and ultimately results in apoptosis.
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Affiliation(s)
- P Andorfer
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Vienna, Austria
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21
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The multiple myeloma associated MMSET gene contributes to cellular adhesion, clonogenic growth, and tumorigenicity. Blood 2007; 111:856-64. [PMID: 17942756 DOI: 10.1182/blood-2007-05-088674] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiple myeloma (MM) is an incurable hematologic malignancy characterized by recurrent chromosomal translocations. Patients with t(4;14)(p16;q32) are the worst prognostic subgroup in MM, although the basis for this poor prognosis is unknown. The t(4;14) is unusual in that it involves 2 potential target genes: fibroblast growth factor receptor 3 (FGFR3) and multiple myeloma SET domain (MMSET). MMSET is universally overexpressed in t(4;14) MM, whereas FGFR3 expression is lost in one-third of cases. Nonetheless, the role of MMSET in t(4;14) MM has remained unclear. Here we demonstrate a role for MMSET in t(4;14) MM cells. Down-regulation of MMSET expression in MM cell lines by RNA interference and by selective disruption of the translocated MMSET allele using gene targeting dramatically reduced colony formation in methylcellulose but had only modest effects in liquid culture. In addition, MMSET knockdown led to cell-cycle arrest of adherent MM cells and reduced the ability of MM cells to adhere to extracellular matrix. Finally, MMSET knockdown and knockout reduced tumor formation by MM xenografts. These results provide the first direct evidence that MMSET plays a significant role in t(4;14) MM and suggest that therapies targeting this gene could impact this particular subset of poor-prognosis patients.
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