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Hammond T, Sage J. Monitoring the Cell Cycle of Tumor Cells in Mouse Models of Human Cancer. Cold Spring Harb Perspect Med 2023; 13:a041383. [PMID: 37460156 PMCID: PMC10691483 DOI: 10.1101/cshperspect.a041383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Cell division is obligatory to tumor growth. However, both cancer cells and noncancer cells in tumors can be found in distinct stages of the cell cycle, which may inform the growth potential of these tumors, their propensity to metastasize, and their response to therapy. Hence, it is of utmost importance to monitor the cell cycle of tumor cells. Here we discuss well-established methods and new genetic advances to track the cell cycle of tumor cells in mouse models of human cancer. We also review recent genetic studies investigating the role of the cell-cycle machinery in the growth of tumors in vivo, with a focus on the machinery regulating the G1/S transition of the cell cycle.
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Affiliation(s)
- Taylar Hammond
- Department of Pediatrics, Stanford University, Stanford, California 94305, USA
- Department of Biology, and Stanford University, Stanford, California 94305, USA
| | - Julien Sage
- Department of Pediatrics, Stanford University, Stanford, California 94305, USA
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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2
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Jiang Z, Li H, Schroer SA, Voisin V, Ju Y, Pacal M, Erdmann N, Shi W, Chung PED, Deng T, Chen NJ, Ciavarra G, Datti A, Mak TW, Harrington L, Dick FA, Bader GD, Bremner R, Woo M, Zacksenhaus E. Hypophosphorylated pRb knock-in mice exhibit hallmarks of aging and vitamin C-preventable diabetes. EMBO J 2022; 41:e106825. [PMID: 35023164 PMCID: PMC8844977 DOI: 10.15252/embj.2020106825] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/29/2021] [Accepted: 12/08/2021] [Indexed: 12/25/2022] Open
Abstract
Despite extensive analysis of pRB phosphorylation in vitro, how this modification influences development and homeostasis in vivo is unclear. Here, we show that homozygous Rb∆K4 and Rb∆K7 knock‐in mice, in which either four or all seven phosphorylation sites in the C‐terminal region of pRb, respectively, have been abolished by Ser/Thr‐to‐Ala substitutions, undergo normal embryogenesis and early development, notwithstanding suppressed phosphorylation of additional upstream sites. Whereas Rb∆K4 mice exhibit telomere attrition but no other abnormalities, Rb∆K7 mice are smaller and display additional hallmarks of premature aging including infertility, kyphosis, and diabetes, indicating an accumulative effect of blocking pRb phosphorylation. Diabetes in Rb∆K7 mice is insulin‐sensitive and associated with failure of quiescent pancreatic β‐cells to re‐enter the cell cycle in response to mitogens, resulting in induction of DNA damage response (DDR), senescence‐associated secretory phenotype (SASP), and reduced pancreatic islet mass and circulating insulin level. Pre‐treatment with the epigenetic regulator vitamin C reduces DDR, increases cell cycle re‐entry, improves islet morphology, and attenuates diabetes. These results have direct implications for cell cycle regulation, CDK‐inhibitor therapeutics, diabetes, and longevity.
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Affiliation(s)
- Zhe Jiang
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Huiqin Li
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Stephanie A Schroer
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Veronique Voisin
- The Donnelly Centre, Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - YoungJun Ju
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Marek Pacal
- Lunenfeld Tanenbaum Research Institute - Sinai Health System, Mount Sinai Hospital, Department of Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Natalie Erdmann
- Campbell Family Institute for Breast Cancer Research, Princess Margaret Hospital, Toronto, ON, Canada
| | - Wei Shi
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Philip E D Chung
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Tao Deng
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Nien-Jung Chen
- Campbell Family Institute for Breast Cancer Research, Princess Margaret Hospital, Toronto, ON, Canada
| | - Giovanni Ciavarra
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Alessandro Datti
- Department of Agriculture, Food, and Environmental Sciences, University of Perugia, Perugia, Italy.,Network Biology Collaborative Centre, SMART Laboratory for High-Throughput Screening Programs, Mount Sinai Hospital, Toronto, ON, Canada
| | - Tak W Mak
- Campbell Family Institute for Breast Cancer Research, Princess Margaret Hospital, Toronto, ON, Canada
| | - Lea Harrington
- Department of Medicine, Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC, Canada
| | - Frederick A Dick
- Department of Biochemistry, Western University, London, ON, Canada
| | - Gary D Bader
- The Donnelly Centre, Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Rod Bremner
- Lunenfeld Tanenbaum Research Institute - Sinai Health System, Mount Sinai Hospital, Department of Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Minna Woo
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Eldad Zacksenhaus
- Max Bell Research Centre, Toronto General Research Institute, University Health Network, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
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3
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Sheikh-Hosseini M, Larijani B, Gholipoor Kakroodi Z, Shokoohi M, Moarefzadeh M, Sayahpour FA, Goodarzi P, Arjmand B. Gene Therapy as an Emerging Therapeutic Approach to Breast Cancer: New Developments and Challenges. Hum Gene Ther 2021; 32:1330-1345. [PMID: 33307949 DOI: 10.1089/hum.2020.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Breast cancer is a heterogeneous disease, which is the consequence of several genetic and environmental factors. Also, it is one of the most common causes of cancer death and second leading cancer among women all around the world. Therefore, it is necessary to develop novel therapeutic approaches useful for the successful treatment of breast cancer. As conventional treatments had limited success, alternative approaches for the treatment of breast cancer have been applied in recent years. Hence, the molecular basis of breast cancer has provided the opportunity of using genetic materials for therapeutic uses. In this regard, gene therapy as one of the potentially efficient and beneficial treatments among various techniques became a popular treatment for different cancers, especially breast cancer. Accordingly, there are plenty of targets available for gene therapy of breast cancer. Gene therapy strategies have the potential to correct molecular defects that contributed to the cancer progression. These techniques should selectively target tumor cells without affecting normal cells. Moreover, data of clinical trials in gene therapy for breast cancer indicated that this approach has little toxicity compared to other therapeutic approaches. In this study, different aspects of breast neoplasm, gene therapy techniques, challenges, and recent developments will be mentioned.
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Affiliation(s)
- Motahareh Sheikh-Hosseini
- Metabolomics and Genomics Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Gholipoor Kakroodi
- Cell Therapy and Regenerative Medicine Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahshid Shokoohi
- Cell Therapy and Regenerative Medicine Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Moarefzadeh
- Cell Therapy and Regenerative Medicine Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Forough Azam Sayahpour
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Parisa Goodarzi
- Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Babak Arjmand
- Metabolomics and Genomics Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.,Cell Therapy and Regenerative Medicine Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
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4
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Datta N, Chakraborty S, Basu M, Ghosh MK. Tumor Suppressors Having Oncogenic Functions: The Double Agents. Cells 2020; 10:cells10010046. [PMID: 33396222 PMCID: PMC7824251 DOI: 10.3390/cells10010046] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/23/2020] [Accepted: 12/25/2020] [Indexed: 12/17/2022] Open
Abstract
Cancer progression involves multiple genetic and epigenetic events, which involve gain-of-functions of oncogenes and loss-of-functions of tumor suppressor genes. Classical tumor suppressor genes are recessive in nature, anti-proliferative, and frequently found inactivated or mutated in cancers. However, extensive research over the last few years have elucidated that certain tumor suppressor genes do not conform to these standard definitions and might act as “double agents”, playing contrasting roles in vivo in cells, where either due to haploinsufficiency, epigenetic hypermethylation, or due to involvement with multiple genetic and oncogenic events, they play an enhanced proliferative role and facilitate the pathogenesis of cancer. This review discusses and highlights some of these exceptions; the genetic events, cellular contexts, and mechanisms by which four important tumor suppressors—pRb, PTEN, FOXO, and PML display their oncogenic potentials and pro-survival traits in cancer.
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Affiliation(s)
- Neerajana Datta
- Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), TRUE Campus, CN-6, Sector–V, Salt Lake, Kolkata-700091 & 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700032, India; (N.D.); (S.C.)
| | - Shrabastee Chakraborty
- Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), TRUE Campus, CN-6, Sector–V, Salt Lake, Kolkata-700091 & 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700032, India; (N.D.); (S.C.)
| | - Malini Basu
- Department of Microbiology, Dhruba Chand Halder College, Dakshin Barasat, South 24 Paraganas, West Bengal PIN-743372, India;
| | - Mrinal K. Ghosh
- Cancer Biology and Inflammatory Disorder Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), TRUE Campus, CN-6, Sector–V, Salt Lake, Kolkata-700091 & 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700032, India; (N.D.); (S.C.)
- Correspondence:
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5
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Pauciullo A, Shuiep ET, Ogah MD, Cosenza G, Di Stasio L, Erhardt G. Casein Gene Cluster in Camelids: Comparative Genome Analysis and New Findings on Haplotype Variability and Physical Mapping. Front Genet 2019; 10:748. [PMID: 31555318 PMCID: PMC6726744 DOI: 10.3389/fgene.2019.00748] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 07/17/2019] [Indexed: 12/22/2022] Open
Abstract
The structure of casein genes has been fully understood in llamas, whereas in other camelids, this information is still incomplete. In fact, structure and polymorphisms have been identified in three (CSN1S1, αs1-CN; CSN2, β-CN; CSN3, κ-CN) out of four casein genes, whereas controversial information is available for the CSN1S2 (αs2-CN) in terms of structure and genetic diversity. Data from the genome analysis, whose assembly is available for feral camel, Bactrian, dromedary, and alpaca, can contribute to a better knowledge. However, a majority of the scaffolds available in GenBank are still unplaced, and the comparative annotation is often inaccurate or lacking.Therefore, the aims of this study are 1) to perform a comparative genome analysis and synthesize the literature data on camelids casein cluster; 2) to analyze the casein variability in two dromedary populations (Sudanese and Nigerian) using polymorphisms at CSN1S1 (c.150G > T), CSN2 (g.2126A > G), and CSN3 (g.1029T > C); and 3) to physically map the casein cluster in alpaca. Exon structures, gene and intergenic distances, large insertion/deletion events, SNPs, and microsatellites were annotated. In all camelids, the CSN1S2 consists of 17 exons, confirming the structure of llama CSN1S2 gene. The comparative analysis of the complete casein cluster (∼190kb) shows 12,818 polymorphisms. The most polymorphic gene is the CSN1S1 (99 SNPs in Bactrian vs. 248 in dromedary vs. 626 in alpaca). The less polymorphic is the CSN3 in the Bactrian (22 SNPs) and alpaca (301 SNPs), whereas it is the CSN1S2 in dromedary (79 SNPs). In the two investigated dromedary populations, the allele frequencies for the three markers are slightly different: the allele C at CSN1S1 is very rare in Nigerian (0.054) and Sudanese dromedaries (0.094), whereas the frequency of the allele G at CSN2 is almost inverted. Haplotype analysis evidenced GAC as the most frequent (0.288) and TGC as the rarest (0.005). The analysis of R-banding metaphases hybridized with specific probes mapped the casein genes on chromosome 2q21 in alpaca. These data deepen the information on the structure of the casein cluster in camelids and add knowledge on the cytogenetic map and haplotype variability.
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Affiliation(s)
- Alfredo Pauciullo
- Department of Agricultural, Forest and Food Sciences, University of Torino, Grugliasco, Italy
| | - El Tahir Shuiep
- Institute of Molecular Biology, University of Nyala, Nyala, Sudan
| | - Moses Danlami Ogah
- Department of Animal Science, Nasarawa State University, Keffi, Shabu-Lafia, Nigeria
| | - Gianfranco Cosenza
- Department of Agriculture, University of Napoli Federico II, Portici Italy
| | - Liliana Di Stasio
- Department of Agricultural, Forest and Food Sciences, University of Torino, Grugliasco, Italy
| | - Georg Erhardt
- Department for Animal Breeding and Genetics, Justus Liebig University, Gießen, Germany
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6
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Xie Z, Zeng X. DNA/RNA-based formulations for treatment of breast cancer. Expert Opin Drug Deliv 2017; 14:1379-1393. [DOI: 10.1080/17425247.2017.1317744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Zhaolu Xie
- Department of Pharmacy, Daping Hospital & Research Institute of Surgery, Third Military Medical University, Chongqing, China
| | - Xianghui Zeng
- Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark
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Abstract
We have previously demonstrated that the retinoblastoma gene family, Rb, p107 and p130, is differentially expressed during mouse embryogenesis. Here we show that this gene family is coordinately regulated in the mammary luminal epithelium. Expression of Rb, p107 and p130 in the epithelial compartment is low in nulliparous female mice and early stages of pregnancy but is induced at mid-pregnancy and peaks at lactation. During involution p107 expression is lost whereas expression pRb and p130 persist. The induction of this gene family at mid-pregnancy accompanies the expression of beta-casein. However, whereas beta-casein transcripts are confined to the lobuloalveolar compartment, the Rb gene family is expressed both in lobuloalveoli and ducts. The co-expression of the Rb family in the mammary gland may allow functional compensation among these family members. This in turn may explain the recent observations that loss of Rb alone in the mammary gland is inconsequential, whereas overexpression of cyclin D1 or SV40 large T antigen, which can abrogate all members of the pRb protein family, induces mammary gland carcinogenesis.
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Affiliation(s)
- Zhe Jiang
- Department of Medicine, University of Toronto, Division of Cell & Molecular Biology, Toronto General Research Institute--University Health Network, 67 College Street, Toronto, Ontario M5G 2M1, Canada
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8
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Pauciullo A, Erhardt G. Molecular Characterization of the Llamas (Lama glama) Casein Cluster Genes Transcripts (CSN1S1, CSN2, CSN1S2, CSN3) and Regulatory Regions. PLoS One 2015; 10:e0124963. [PMID: 25923814 PMCID: PMC4414411 DOI: 10.1371/journal.pone.0124963] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/19/2015] [Indexed: 11/19/2022] Open
Abstract
In the present paper, we report for the first time the characterization of llama (Lama glama) caseins at transcriptomic and genetic level. A total of 288 casein clones transcripts were analysed from two lactating llamas. The most represented mRNA populations were those correctly assembled (85.07%) and they encoded for mature proteins of 215, 217, 187 and 162 amino acids respectively for the CSN1S1, CSN2, CSN1S2 and CSN3 genes. The exonic subdivision evidenced a structure made of 21, 9, 17 and 6 exons for the αs1-, β-, αs2- and κ-casein genes respectively. Exon skipping and duplication events were evidenced. Two variants A and B were identified in the αs1-casein gene as result of the alternative out-splicing of the exon 18. An additional exon coding for a novel esapeptide was found to be cryptic in the κ-casein gene, whereas one extra exon was found in the αs2-casein gene by the comparison with the Camelus dromedaries sequence. A total of 28 putative phosphorylated motifs highlighted a complex heterogeneity and a potential variable degree of post-translational modifications. Ninety-six polymorphic sites were found through the comparison of the lama casein cDNAs with the homologous camel sequences, whereas the first description and characterization of the 5'- and 3'-regulatory regions allowed to identify the main putative consensus sequences involved in the casein genes expression, thus opening the way to new investigations -so far- never achieved in this species.
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Affiliation(s)
- Alfredo Pauciullo
- Department of Agricultural, Forest and Food Sciences, University of Torino, Grugliasco, Italy
- Institute for Animal Breeding and Genetics, Justus Liebig University, Gießen, Germany
| | - Georg Erhardt
- Institute for Animal Breeding and Genetics, Justus Liebig University, Gießen, Germany
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9
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Boudreau CE, York D, Higgins RJ, LeCouteur RA, Dickinson PJ. Molecular signalling pathways in canine gliomas. Vet Comp Oncol 2015; 15:133-150. [PMID: 25808605 DOI: 10.1111/vco.12147] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 02/04/2015] [Accepted: 02/19/2015] [Indexed: 12/22/2022]
Abstract
In this study, we determined the expression of key signalling pathway proteins TP53, MDM2, P21, AKT, PTEN, RB1, P16, MTOR and MAPK in canine gliomas using western blotting. Protein expression was defined in three canine astrocytic glioma cell lines treated with CCNU, temozolamide or CPT-11 and was further evaluated in 22 spontaneous gliomas including high and low grade astrocytomas, high grade oligodendrogliomas and mixed oligoastrocytomas. Response to chemotherapeutic agents and cell survival were similar to that reported in human glioma cell lines. Alterations in expression of key human gliomagenesis pathway proteins were common in canine glioma tumour samples and segregated between oligodendroglial and astrocytic tumour types for some pathways. Both similarities and differences in protein expression were defined for canine gliomas compared to those reported in human tumour counterparts. The findings may inform more defined assessment of specific signalling pathways for targeted therapy of canine gliomas.
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Affiliation(s)
- C E Boudreau
- Department of Small Animal Clinical Sciences, Texas A&M, College Station, TX, USA
| | - D York
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - R J Higgins
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - R A LeCouteur
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - P J Dickinson
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
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10
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The serine protease inhibitor elafin maintains normal growth control by opposing the mitogenic effects of neutrophil elastase. Oncogene 2014; 34:3556-67. [PMID: 25195861 PMCID: PMC4362782 DOI: 10.1038/onc.2014.284] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 06/22/2014] [Accepted: 07/19/2014] [Indexed: 12/22/2022]
Abstract
The serine protease inhibitor, elafin, is a critical component of the epithelial barrier against neutrophil elastase (NE). Elafin is downregulated in the majority of breast cancer cell lines compared to normal human mammary epithelial cells (HMECs). Here, we evaluated the role of elafin and NE on proliferation and tumorigenesis. Elafin is induced in growth factor deprived HMECs as they enter a quiescent (G0) state, suggesting that elafin is a counterbalance against the mitogenic effects of NE in G0 HMECs. Stable knockdown of elafin compromises the ability of HMECs to maintain G0-arrest during long-term growth factor deprivation; this effect can be reversed by re-expression of wild-type elafin, but not elafin-M25G lacking protease inhibitory function. These results suggest that NE, which is largely contributed by activated neutrophils in the tumor microenvironment, may be negatively regulating the ability of elafin to arrest cells in G0. In fact when purified NE was added to elafin knockdown HMECs, these cells demonstrated greater sensitivity to the growth promoting effects of purified NE. Activation of ERK signaling, downstream of toll-like receptor 4, was essential to the mitogenic effect of NE on HMECs. These findings were next translated to patient samples, and immunohistochemical analysis of normal breast tissue revealed robust elafin expression in the mammary epithelium; however, elafin expression was dramatically downregulated in a significant proportion of human breast tumor specimens. The loss of elafin expression during breast cancer progression may promote tumor growth as a consequence of increased NE-activity. To address the role of NE in mammary tumorigenesis, we next examined if deregulated NE-activity enhances mammary tumor growth. NE knockout in the C3(1)TAg mouse model of mammary tumorigenesis suppressed proliferation and reduced the kinetics of tumor growth. Overall, the imbalance between NE and its inhibitors, such as elafin, presents an important therapeutic target in breast cancer.
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Lou X, Zhang J, Liu S, Xu N, Liao DJ. The other side of the coin: the tumor-suppressive aspect of oncogenes and the oncogenic aspect of tumor-suppressive genes, such as those along the CCND-CDK4/6-RB axis. Cell Cycle 2014; 13:1677-93. [PMID: 24799665 DOI: 10.4161/cc.29082] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Although cancer-regulatory genes are dichotomized to oncogenes and tumor-suppressor gene s, in reality they can be oncogenic in one situation but tumor-suppressive in another. This dual-function nature, which sometimes hampers our understanding of tumor biology, has several manifestations: (1) Most canonically defined genes have multiple mRNAs, regulatory RNAs, protein isoforms, and posttranslational modifications; (2) Genes may interact at different levels, such as by forming chimeric RNAs or by forming different protein complexes; (3) Increased levels of tumor-suppressive genes in normal cells drive proliferation of cancer progenitor cells in the same organ or tissue by imposing compensatory proliferation pressure, which presents the dual-function nature as a cell-cell interaction. All these manifestations of dual functions can find examples in the genes along the CCND-CDK4/6-RB axis. The dual-function nature also underlies the heterogeneity of cancer cells. Gene-targeting chemotherapies, including that targets CDK4, are effective to some cancer cells but in the meantime may promote growth or progression of some others in the same patient. Redefining "gene" by considering each mRNA, regulatory RNA, protein isoform, and posttranslational modification from the same genomic locus as a "gene" may help in better understanding tumor biology and better selecting targets for different sub-populations of cancer cells in individual patients for personalized therapy.
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Affiliation(s)
- Xiaomin Lou
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Ju Zhang
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Siqi Liu
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Ningzhi Xu
- Laboratory of Cell and Molecular Biology; Cancer Institute; Chinese Academy of Medical Science; Beijing, PR China
| | - D Joshua Liao
- Hormel Institute; University of Minnesota; Austin, MN USA
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12
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Kim KJ, Godarova A, Seedle K, Kim MH, Ince TA, Wells SI, Driscoll JJ, Godar S. Rb suppresses collective invasion, circulation and metastasis of breast cancer cells in CD44-dependent manner. PLoS One 2013; 8:e80590. [PMID: 24324613 PMCID: PMC3851742 DOI: 10.1371/journal.pone.0080590] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/04/2013] [Indexed: 01/06/2023] Open
Abstract
Basal-like breast carcinomas (BLCs) present with extratumoral lymphovascular invasion, are highly metastatic, presumably through a hematogenous route, have augmented expression of CD44 oncoprotein and relatively low levels of retinoblastoma (Rb) tumor suppressor. However, the causal relation among these features is not clear. Here, we show that Rb acts as a key suppressor of multiple stages of metastatic progression. Firstly, Rb suppresses collective cell migration (CCM) and CD44-dependent formation of F-actin positive protrusions in vitro and cell-cluster based lymphovascular invasion in vivo. Secondly, Rb inhibits the release of single cancer cells and cell clusters into the hematogenous circulation and subsequent metastatic growth in lungs. Finally, CD44 expression is required for collective motility and all subsequent stages of metastatic progression initiated by loss of Rb function. Altogether, our results suggest that Rb/CD44 pathway is a crucial regulator of CCM and metastatic progression of BLCs and a promising target for anti-BLCs therapy.
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MESH Headings
- Actins/genetics
- Actins/metabolism
- Animals
- Carcinoma, Basal Cell/genetics
- Carcinoma, Basal Cell/metabolism
- Carcinoma, Basal Cell/secondary
- Cell Line, Tumor
- Cell Movement
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- Hyaluronan Receptors/genetics
- Hyaluronan Receptors/metabolism
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/secondary
- Lymphatic Metastasis
- Mammary Neoplasms, Experimental/genetics
- Mammary Neoplasms, Experimental/metabolism
- Mammary Neoplasms, Experimental/pathology
- Mice
- Neoplastic Cells, Circulating/metabolism
- Neoplastic Cells, Circulating/pathology
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Retinoblastoma Protein/antagonists & inhibitors
- Retinoblastoma Protein/genetics
- Retinoblastoma Protein/metabolism
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Affiliation(s)
- Kui-Jin Kim
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Alzbeta Godarova
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Kari Seedle
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Min-Ho Kim
- Biomedical Research Center, Ulsan University Hospital, Ulsan, Republic of Korea
| | - Tan A. Ince
- Department of Pathology, Braman Family Breast Cancer Institute and Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Susanne I. Wells
- Division of Oncology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - James J. Driscoll
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- Division of Hematology and Oncology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Samuel Godar
- Department of Cancer Biology, Vontz Center for Molecular Studies, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
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13
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Carr JR, Kiefer MM, Park HJ, Li J, Wang Z, Fontanarosa J, DeWaal D, Kopanja D, Benevolenskaya EV, Guzman G, Raychaudhuri P. FoxM1 regulates mammary luminal cell fate. Cell Rep 2012; 1:715-29. [PMID: 22813746 PMCID: PMC3401379 DOI: 10.1016/j.celrep.2012.05.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 04/23/2012] [Accepted: 05/07/2012] [Indexed: 01/04/2023] Open
Abstract
Elevated expression of FoxM1 in breast cancer correlates with an undifferentiated tumor phenotype and a negative clinical outcome. However, a role for FoxM1 in regulating mammary differentiation was not known. Here, we identify another function of FoxM1, the ability to act as a transcriptional repressor, which plays an important role in regulating the differentiation of luminal epithelial progenitors. Regeneration of mammary glands with elevated levels of FoxM1 leads to aberrant ductal morphology and expansion of the luminal progenitor pool. Conversely, knockdown of FoxM1 results in a shift toward the differentiated state. FoxM1 mediates these effects by repressing the key regulator of luminal differentiation, GATA-3. Through association with DNMT3b, FoxM1 promotes methylation of the GATA-3 promoter in an Rb-dependent manner. This study identifies FoxM1 as a critical regulator of mammary differentiation with significant implications for the development of aggressive breast cancers.
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MESH Headings
- Animals
- Base Sequence
- Binding Sites
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Cell Differentiation
- Cell Line, Tumor
- Cell Lineage
- Cell Proliferation
- DNA (Cytosine-5-)-Methyltransferases
- DNA Methylation/genetics
- Female
- Forkhead Box Protein M1
- Forkhead Transcription Factors/metabolism
- GATA3 Transcription Factor/metabolism
- Gene Knockdown Techniques
- Humans
- Mammary Glands, Animal/growth & development
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/pathology
- Mammary Glands, Human/growth & development
- Mammary Glands, Human/metabolism
- Mammary Glands, Human/pathology
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Pregnancy
- Promoter Regions, Genetic/genetics
- Retinoblastoma Protein/metabolism
- Transcription, Genetic
- DNA Methyltransferase 3B
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Affiliation(s)
- Janai R. Carr
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Megan M. Kiefer
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Hyun Jung Park
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Jing Li
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Zebin Wang
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Joel Fontanarosa
- Bioinformatics Program Department of Bioengineering, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Danielle DeWaal
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Dragana Kopanja
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Elizaveta V. Benevolenskaya
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Grace Guzman
- Department of Pathology, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
| | - Pradip Raychaudhuri
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, College of Medicine, Chicago, Illinois, 60607, USA
- Jesse Brown VA Medical Center, Chicago, Illinois, 60612, USA
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14
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Wang B, Hikosaka K, Sultana N, Sharkar MTK, Noritake H, Kimura W, Wu YX, Kobayashi Y, Uezato T, Miura N. Liver tumor formation by a mutant retinoblastoma protein in the transgenic mice is caused by an upregulation of c-Myc target genes. Biochem Biophys Res Commun 2012; 417:601-6. [DOI: 10.1016/j.bbrc.2011.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 12/05/2011] [Indexed: 12/29/2022]
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15
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Abstract
The retinoblastoma (RB) tumor suppressor belongs to a cellular pathway that plays a crucial role in restricting the G1-S transition of the cell cycle in response to a large number of extracellular and intracellular cues. Research in the last decade has highlighted the complexity of regulatory networks that ensure proper cell cycle progression, and has also identified multiple cellular functions beyond cell cycle regulation for RB and its two family members, p107 and p130. Here we review some of the recent evidence pointing to a role of RB as a molecular adaptor at the crossroads of multiple pathways, ensuring cellular homeostasis in different contexts. In particular, we discuss the pro- and anti-tumorigenic roles of RB during the early stages of cancer, as well as the importance of the RB pathway in stem cells and cell fate decisions.
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Affiliation(s)
- Patrick Viatour
- Department of Genetics, Stanford University, Stanford, CA 94305, USA.
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16
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Larsson LG. Oncogene- and tumor suppressor gene-mediated suppression of cellular senescence. Semin Cancer Biol 2011; 21:367-76. [PMID: 22037160 DOI: 10.1016/j.semcancer.2011.10.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Data accumulating during the last two decades suggest that tumorigenesis is held in check by two major intrinsic failsafe mechanisms; apoptosis and cellular senescence. While apoptosis is a programmed cell death process, cellular senescence, which is the focus of this article, is defined as irreversible cell cycle arrest. This process is triggered either by telomere erosion or by acute stress signals including oncogenic stress induced by overactive oncogenes or underactive tumor suppressor genes. The outcome of this is often replication overload and oxidative stress resulting in DNA damage. Oncogenic stress induces at least three intrinsic pathways, p16/pRb-, Arf/p53/p21- and the DNA damage response (DDR)-pathways, that induce premature senescence if the stress exceeds a threshold level. Oncogene-induced senescence (OIS) is frequently observed in premalignant lesions both in animal tumor models and in human patients but is essentially absent in advanced cancers, suggesting that malignant tumor cells have found ways to bypass or escape senescence. This review focuses on cell-autonomous mechanism by which certain oncogenes, tumor suppressor genes and components of the DDR/DNA-repair machinery suppress senescence - mechanisms that are exploited by tumor cells to evade senescence and continue to multiply. In this way, tumor cells become addicted to the continuous activity of senescence suppressor proteins. However, some senescence pathways, although under suppression, may remain intact and can be re-established if senescence suppressor proteins are inactivated or if senescence inducers are reactivated. This can hopefully form the basis for a "pro-senescence therapy" strategy to combat cancer in the future.
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Affiliation(s)
- Lars-Gunnar Larsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Box 280, SE-171 77 Stockholm, Sweden.
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17
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Węsierska-Gądek J, Kramer MP. The impact of multi-targeted cyclin-dependent kinase inhibition in breast cancer cells: clinical implications. Expert Opin Investig Drugs 2011; 20:1611-28. [PMID: 22017180 DOI: 10.1517/13543784.2011.628985] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The progression of the mammalian cell cycle is driven by the transient activation of complexes consisting of cyclins and cyclin-dependent kinases (CDKs). Loss of control over the cell cycle results in accelerated cell division and malignant transformation and can be caused by the upregulation of cyclins, the aberrant activation of CDKs or the inactivation of cellular CDK inhibitors. For these reasons, cell cycle regulators are regarded as very promising therapeutic targets for the treatment of human malignancies. AREAS COVERED This review covers the structures and anti-breast cancer activity of selected pharmacological pan-specific CDK inhibitors. Multi-targeted CDK inhibitors affect CDKs involved in the regulation of both cell cycle progression and transcriptional control. The inhibition of CDK7/CDK9 has a serious impact on the activity of RNA polymerase II; when its carboxy-terminal domain is unphosphorylated, it is unable to recruit the cofactors required for transcriptional elongation, resulting in a global transcriptional block. Multi-targeted inhibition of CDKs represses anti-apoptotic proteins and thus promotes the induction of apoptosis. Moreover, the inhibition of CDK7 in estrogen receptor (ER)-positive breast cancer cells prevents activating phosphorylation of ER-α. EXPERT OPINION These diverse modes of action make multi-targeted CDK inhibitors promising drugs for the treatment of breast cancers.
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Affiliation(s)
- Józefa Węsierska-Gądek
- Medical University of Vienna, Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center, Cell Cycle Regulation Group, Borschkegasse 8a, 1090 Vienna, Austria.
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18
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Abstract
The RB1 gene is the first tumor suppressor gene identified whose mutational inactivation is the cause of a human cancer, the pediatric cancer retinoblastoma. The 25 years of research since its discovery has not only illuminated a general role for RB1 in human cancer, but also its critical importance in normal development. Understanding the molecular function of the RB1 encoded protein, pRb, is a long-standing goal that promises to inform our understanding of cancer, its relationship to normal development, and possible therapeutic strategies to combat this disease. Achieving this goal has been difficult, complicated by the complexity of pRb and related proteins. The goal of this review is to explore the hypothesis that, at its core, the molecular function of pRb is to dynamically regulate the location-specific assembly or disassembly of protein complexes on the DNA in response to the output of various signaling pathways. These protein complexes participate in a variety of molecular processes relevant to DNA including gene transcription, DNA replication, DNA repair, and mitosis. Through regulation of these processes, RB1 plays a uniquely prominent role in normal development and cancer.
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Affiliation(s)
- Meenalakshmi Chinnam
- Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York, USA
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19
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Ciavarra G, Ho AT, Cobrinik D, Zacksenhaus E. Critical role of the Rb family in myoblast survival and fusion. PLoS One 2011; 6:e17682. [PMID: 21423694 PMCID: PMC3053373 DOI: 10.1371/journal.pone.0017682] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 02/08/2011] [Indexed: 12/23/2022] Open
Abstract
The tumor suppressor Rb is thought to control cell proliferation, survival and differentiation. We recently showed that differentiating Rb-deficient mouse myoblasts can fuse to form short myotubes that quickly collapse through a mechanism involving autophagy, and that autophagy inhibitors or hypoxia could rescue the defect leading to long, twitching myotubes. Here we determined the contribution of pRb relatives, p107 and p130, to this process. We show that chronic or acute inactivation of Rb plus p107 or p130 increased myoblast cell death and reduced myotube formation relative to Rb loss alone. Treatment with autophagy antagonists or hypoxia extended survival of double-knockout myotubes, which appeared indistinguishable from control fibers. In contrast, triple mutations in Rb, p107 and p130, led to substantial increase in myoblast death and to elongated bi-nuclear myocytes, which seem to derive from nuclear duplication, as opposed to cell fusion. Under hypoxia, some rare, abnormally thin triple knockout myotubes survived and twitched. Thus, mutation of p107 or p130 reduces survival of Rb-deficient myoblasts during differentiation but does not preclude myoblast fusion or necessitate myotube degeneration, whereas combined inactivation of the entire Rb family produces a distinct phenotype, with drastically impaired myoblast fusion and survival.
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Affiliation(s)
- Giovanni Ciavarra
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Andrew T. Ho
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - David Cobrinik
- Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Eldad Zacksenhaus
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Division of Cell and Molecular Biology, Toronto General Research Institute - University Health Network, Toronto, Ontario, Canada
- * E-mail:
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20
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Ciavarra G, Zacksenhaus E. Rescue of myogenic defects in Rb-deficient cells by inhibition of autophagy or by hypoxia-induced glycolytic shift. ACTA ACUST UNITED AC 2010; 191:291-301. [PMID: 20937698 PMCID: PMC2958467 DOI: 10.1083/jcb.201005067] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The retinoblastoma tumor suppressor (pRb) is thought to orchestrate terminal differentiation by inhibiting cell proliferation and apoptosis and stimulating lineage-specific transcription factors. In this study, we show that in the absence of pRb, differentiating primary myoblasts fuse to form short myotubes that never twitch and degenerate via a nonapoptotic mechanism. The shortened myotubes exhibit an impaired mitochondrial network, mitochondrial perinuclear aggregation, autophagic degradation, and reduced adenosine triphosphate production. Bcl-2 and autophagy inhibitors restore mitochondrial function and rescue muscle degeneration, leading to formation of long, twitching myotubes that express normal levels of muscle-specific proteins and stably exit the cell cycle. A hypoxia-induced glycolytic switch also rescues the myogenic defect after either chronic or acute inactivation of Rb in a hypoxia-inducible factor-1 (HIF-1)-dependent manner. These results demonstrate that pRb is required to inhibit apoptosis in myoblasts and autophagy in myotubes but not to activate the differentiation program, and they also reveal a novel link between pRb and cell metabolism.
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Affiliation(s)
- Giovanni Ciavarra
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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21
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Jiang Z, Deng T, Jones R, Li H, Herschkowitz JI, Liu JC, Weigman VJ, Tsao MS, Lane TF, Perou CM, Zacksenhaus E. Rb deletion in mouse mammary progenitors induces luminal-B or basal-like/EMT tumor subtypes depending on p53 status. J Clin Invest 2010; 120:3296-309. [PMID: 20679727 DOI: 10.1172/jci41490] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 06/09/2010] [Indexed: 12/23/2022] Open
Abstract
Breast cancer is a highly heterogeneous disease, with several different subtypes being characterized by distinct histology, gene expression patterns, and genetic alterations. The tumor suppressor gene retinoblastoma 1 (RB1) is frequently lost in both luminal-B and triple-negative tumor (TNT; i.e., estrogen receptor-, progesterone receptor-, and human epidermal growth factor receptor 2-negative) breast cancer subtypes. However, a causal role for RB1 loss in different subtypes remains undefined. Here we report that deletion of Rb alone or together with its relative p107 in mouse mammary stem/bipotent progenitor cells induced focal acinar hyperplasia with squamous metaplasia. These lesions progressed into histologically diverse, transplantable mammary tumors with features of either luminal-B or TNT subtypes. The TNTs included basal-like tumors as well as tumors that exhibited epithelial-to-mesenchymal transition (EMT). The EMT-type tumors and a subset of the basal-like tumors, but not luminal-B-like tumors, expressed mutant forms of the tumor suppressor p53. Accordingly, targeted deletion of both Rb and p53 in stem/bipotent progenitors led to histologically uniform, aggressive, EMT-type tumors. Reintroduction of Rb into these tumor cells suppressed growth in vitro and tumor formation in vivo. These results establish a causal role for Rb loss in breast cancer in mice and demonstrate that cooperating oncogenic events, such as mutations in p53, dictate tumor subtype after Rb inactivation.
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Affiliation(s)
- Zhe Jiang
- Division of Cell and Molecular Biology, Toronto General Research Institute-University Health Network, Toronto, Ontario, Canada
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22
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Dasgupta B, Milbrandt J. AMP-activated protein kinase phosphorylates retinoblastoma protein to control mammalian brain development. Dev Cell 2009; 16:256-70. [PMID: 19217427 DOI: 10.1016/j.devcel.2009.01.005] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 10/29/2008] [Accepted: 01/20/2009] [Indexed: 12/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is an evolutionarily conserved metabolic sensor that responds to alterations in cellular energy levels to maintain energy balance. While its role in metabolic homeostasis is well documented, its role in mammalian development is less clear. Here we demonstrate that mutant mice lacking the regulatory AMPK beta1 subunit have profound brain abnormalities. The beta1(-/-) mice show atrophy of the dentate gyrus and cerebellum, and severe loss of neurons, oligodendrocytes, and myelination throughout the central nervous system. These abnormalities stem from reduced AMPK activity, with ensuing cell cycle defects in neural stem and progenitor cells (NPCs). The beta1(-/-) NPC deficits result from hypophosphorylation of the retinoblastoma protein (Rb), which is directly phosphorylated by AMPK at Ser(804). The AMPK-Rb axis is utilized by both growth factors and energy restriction to increase NPC growth. Our results reveal that AMPK integrates growth factor signaling with cell cycle control to regulate brain development.
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Affiliation(s)
- Biplab Dasgupta
- Department of Pathology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
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23
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Abstract
The retinoblastoma (RB) tumour suppressor gene is functionally inactivated in a broad range of paediatric and adult cancers, and a plethora of cellular functions and partners have been identified for the RB protein. Data from human tumours and studies from mouse models indicate that loss of RB function contributes to both cancer initiation and progression. However, we still do not know the identity of the cell types in which RB normally prevents cancer initiation in vivo, and the specific functions of RB that suppress distinct aspects of the tumorigenic process are poorly understood.
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Affiliation(s)
- Deborah L Burkhart
- Cancer Biology Program, Stanford University School of Medicine, Stanford, California 94305, USA
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24
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Overexpression of Cdk5 or non-phosphorylatable retinoblastoma protein protects septal neurons from oxygen-glucose deprivation. Neurochem Res 2008; 33:1852-8. [PMID: 18351461 DOI: 10.1007/s11064-008-9647-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 02/28/2008] [Indexed: 10/22/2022]
Abstract
Activation of cyclin dependent kinases (Cdks) contributes to neuronal death following ischemia. We used oxygen-glucose deprivation (OGD) in septal neuronal cultures to test for possible roles of cell cycle proteins in neuronal survival. Increased cdc2-immunoreactive neurons were observed at 24 h after the end of 5 h OGD. Green fluorescent protein (GFP) or GFP along with a wild type or dominant negative form of the retinoblastoma protein (Rb), or cyclin-dependent kinase5 (Cdk5), were overexpressed using plasmid constructs. Following OGD, when compared to controls, neurons expressing both GFP and dominant negative Rb, RbDeltaK11, showed significantly less damage using microscopy imaging. Overexpression of Rb-wt did not affect survival. Surprisingly, overexpression of Cdk5-wild type significantly protected neurons from process disintegration but Cdk5T33, a dominant negative Cdk5, gave little or no protection. Thus phosphorylation of the cell cycle regulator, Rb, contributes to death in OGD in septal neurons but Cdk5 can have a protective role.
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25
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Al-Khalaf HH, Lach B, Allam A, Hassounah M, AlKhani A, Elkum N, Alrokayan SA, Aboussekhra A. Expression of survivin and p16INK4a/Cdk6/pRB proteins and induction of apoptosis in response to radiation and cisplatin in meningioma cells. Brain Res 2008; 1188:25-34. [DOI: 10.1016/j.brainres.2007.10.074] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/17/2007] [Accepted: 10/24/2007] [Indexed: 01/22/2023]
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26
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André S, Pinto AE, Laranjeira C, Quaresma M, Soares J. Male and Female Breast Cancer – Differences in DNA Ploidy, p21 and p53 Expression Reinforce the Possibility of Distinct Pathways of Oncogenesis. Pathobiology 2007; 74:323-7. [DOI: 10.1159/000110025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Accepted: 07/06/2007] [Indexed: 12/14/2022] Open
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Fischer A, Stuckas H, Gluth M, Russell TD, Rudolph MC, Beeman NE, Bachmann S, Umemura S, Ohashi Y, Neville MC, Theuring F. Impaired tight junction sealing and precocious involution in mammary glands of PKN1 transgenic mice. J Cell Sci 2007; 120:2272-83. [PMID: 17591691 DOI: 10.1242/jcs.03467] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The mammary gland undergoes a complex set of changes to establish copious milk secretion at parturition. To test the hypothesis that signaling through the Rho pathway plays a role in secretory activation, transgenic mice expressing a constitutively activated form of the Rho effector protein PKN1 in the mammary epithelium were generated. PKN1 activation had no effect in late pregnancy but inhibited milk secretion after parturition, diminishing the ability of transgenic dams to support a litter. Mammary gland morphology as well as increased apoptosis and expression of IFGBP5 and TGFbeta3 suggest precocious involution in these animals. Furthermore, tight junction sealing at parturition was impaired in transgenic mammary glands as demonstrated by intraductal injection of [14C]sucrose. Consistent with this finding, tight junction sealing in response to glucocorticoid stimulation was highly impaired in EpH4 mammary epithelial cells expressing constitutively activated PKN1, whereas expression of a dominant-negative PKN1 mutant resulted in accelerated tight junction sealing in vitro. Tight junction formation was not impaired as demonstrated by the correct localization of occludin and ZO1 at the apical cell borders. Our results provide evidence that PKN1 participates in the regulation of tight junction sealing in the mammary gland by interfering with glucocorticoid signaling.
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Affiliation(s)
- Andreas Fischer
- Institute of Pharmacology, Center for Cardiovascular Research, Charité University Medicine, 10115 Berlin, Germany
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28
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Dick FA. Structure-function analysis of the retinoblastoma tumor suppressor protein - is the whole a sum of its parts? Cell Div 2007; 2:26. [PMID: 17854503 PMCID: PMC2082274 DOI: 10.1186/1747-1028-2-26] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 09/13/2007] [Indexed: 12/28/2022] Open
Abstract
Biochemical analysis of the retinoblastoma protein's function has received considerable attention since it was cloned just over 20 years ago. During this time pRB has emerged as a key regulator of the cell division cycle and its ability to block proliferation is disrupted in the vast majority of human cancers. Much has been learned about the regulation of E2F transcription factors by pRB in the cell cycle. However, many questions remain unresolved and researchers continue to explore this multifunctional protein. In particular, understanding how its biochemical functions contribute to its role as a tumor suppressor remains to be determined. Since pRB has been shown to function as an adaptor molecule that links different proteins together, or to particular promoters, analyzing pRB by disrupting individual protein interactions holds tremendous promise in unraveling the intricacies of its function. Recently, crystal structures have reported how pRB interacts with some of its molecular partners. This information has created the possibility of rationally separating pRB functions by studying mutants that disrupt individual binding sites. This review will focus on literature that investigates pRB by isolating functions based on binding sites within the pocket domain. This article will also discuss the prospects for using this approach to further explore the unknown functions of pRB.
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29
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Liu CWY, Wang RH, Berndt N. Protein phosphatase 1alpha activity prevents oncogenic transformation. Mol Carcinog 2006; 45:648-56. [PMID: 16550609 DOI: 10.1002/mc.20191] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cyclin-dependent kinase 2 (Cdk2) phosphorylates Thr320 of protein phosphatase 1alpha (PP1alpha) in late G(1), thereby inhibiting its activity. Phosphorylation-resistant PP1alphaT320A, acting as a constitutively active (CA) mutant, causes a late G(1) arrest by preventing the phosphorylation and inactivation of the retinoblastoma protein (pRb). Both PP1alpha-mediated G(1) arrest and PP1alpha phosphorylation in late G(1) require the presence of pRb, indicating that PP1alpha is a crucial regulator of the pRb pathway, which is almost invariably mutated in human cancer. These findings prompted us to investigate whether PP1alpha interferes with oncogenic transformation. The ability of NIH 3T3 cells to form foci after transformation with ras/cyclin D1 was significantly inhibited by co-transfection with PP1alphaT320A, but not PP1alpha. Likewise, cells expressing PP1alphaT320A or PP1alphaT320A fused to green fluorescent protein (GFP) were unable to form colonies in soft agar, regardless of whether PP1alpha constructs were co-transfected with ras/cyclin D1 or transfected into stably transformed cells. Overexpressed wild-type (Wt) PP1alpha and GFP-PP1alpha were phosphorylated in Thr320, most likely explaining its lack of effect. Expression of GFP-PP1alphaT320A was associated with caspase-cleaved pRb in Western blots (WB) and morphological signs of cell death. These findings demonstrate that PP1alpha activity can override oncogenic signaling by causing cell-cycle arrest and/or apoptosis rather than restoring contact inhibition or anchorage dependence.
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Affiliation(s)
- Cathy W Y Liu
- Division of Hematology/Oncology, Childrens Hospital Los Angeles, The University of Southern California Keck School of Medicine, Los Angeles, 90027, USA
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30
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Garin E, Lemieux M, Coulombe Y, Robinson GW, Jeannotte L. Stromal Hoxa5 function controls the growth and differentiation of mammary alveolar epithelium. Dev Dyn 2006; 235:1858-71. [PMID: 16607641 DOI: 10.1002/dvdy.20822] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recent progress has enlightened the involvement of Hox genes in organogenesis. Several Hox genes are expressed in normal and neoplastic mammary glands. Using Hoxa5 mutant mice, we showed that Hoxa5-/- females present nursing defects. Characterization of the Hoxa5-/- mammary gland phenotype reveals changes in proliferation and differentiation of the epithelium of nulliparous and pregnant Hoxa5-/- females that precede the abnormal secretory activity at parturition. These defects likely underlie the incapacity of Hoxa5-/- dams to properly feed their pups. Hoxa5 expression is restricted to the mammary stroma at specific stages of mammary gland development. The loss of Hoxa5 function causes accelerated lobuloalveolar epithelium development, a phenotype that can be rescued upon grafting of mutant mammary epithelium into wild-type fat pads. Conversely, reciprocal grafting experiments demonstrate that Hoxa5-/- stroma cannot support normal proliferation of wild-type mammary epithelium. These data establish the essential contribution of Hoxa5 to mammary epithelium instruction by means of mesenchymal-epithelial crosstalk.
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Affiliation(s)
- Elisabeth Garin
- Centre de recherche en cancérologie de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, Canada
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31
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Abstract
The retinoblastoma tumor-suppressor gene (Rb1) is centrally important in cancer research. Mutational inactivation of Rb1 causes the pediatric cancer retinoblastoma, while deregulation of the pathway in which it functions is common in most types of human cancer. The Rb1-encoded protein (pRb) is well known as a general cell cycle regulator, and this activity is critical for pRb-mediated tumor suppression. The main focus of this review, however, is on more recent evidence demonstrating the existence of additional, cell type-specific pRb functions in cellular differentiation and survival. These additional functions are relevant to carcinogenesis suggesting that the net effect of Rb1 loss on the behavior of resulting tumors is highly dependent on biological context. The molecular mechanisms underlying pRb functions are based on the cellular proteins it interacts with and the functional consequences of those interactions. Better insight into pRb-mediated tumor suppression and clinical exploitation of pRb as a therapeutic target will require a global view of the complex, interdependent network of pocket protein complexes that function simultaneously within given tissues.
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Affiliation(s)
- D W Goodrich
- Department of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
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St-Pierre B, Jiang Z, Egan SE, Zacksenhaus E. High expression during neurogenesis but not mammogenesis of a murine homologue of the Deleted in Breast Cancer2/Rhobtb2 tumor suppressor. Gene Expr Patterns 2006; 5:245-51. [PMID: 15567721 DOI: 10.1016/j.modgep.2004.07.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Revised: 07/13/2004] [Accepted: 07/21/2004] [Indexed: 12/31/2022]
Abstract
Deleted in Breast Cancer-2, Dbc2, identified as a candidate tumor suppressor gene for breast cancer and other human malignancies, is a member of a novel gene family encoding putative small GTPases designated as Rhobtb. In this report, we describe the spatio-temporal expression of mDbc2/Rhobtb2 mRNA during mammary gland development and embryogenesis in the mouse. We have first determined that mDbc2/Rhobtb2 transcripts are expressed at low, but seemingly constant levels during mammopoiesis. Secondly, we have found that mDbc2/Rhobtb2 is expressed highly and specifically in the central and peripheral nervous systems during mouse embryogenesis. While our results do not reveal any connection between elevated expression of mDbc2/Rhobtb2 and a specific stage of mammary gland development, they strongly support a role for this gene during development of the nervous system.
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Affiliation(s)
- Benoit St-Pierre
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, Ont., Canada M5G 2M1
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Abstract
In view of the limited success of available treatment modalities for breast cancer, alternative and complementary strategies need to be developed. The delineation of the molecular basis of breast cancer provides the possibility of specific intervention by gene therapy through the introduction of genetic material for therapeutic purposes. In this regard, several gene therapy approaches for carcinoma of the breast have been developed. These approaches can be divided into six broad categories: (1) mutation compensation, (2) molecular chemotherapy, (3) proapoptotic gene therapy, (4) antiangiogenic gene therapy, (5) genetic immunopotentiation, and (6) genetic modulation of resistance/sensitivity. Clinical trials for breast cancer have been initiated to evaluate safety, toxicity, and efficacy. Combined modality therapy with gene therapy and chemotherapy or radiation therapy has shown promising results. It is expected that as new therapeutic targets and approaches are identified and advances in vector design are realized, gene therapy will play an increasing role in clinical breast cancer treatment.
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Affiliation(s)
- MA Stoff-Khalili
- Division of Human Gene Therapy, Departments of Medicine, Surgery, Pathology and the Gene Therapy Center, University of Alabama at Birmingham, Birminham, AL, USA
- Department of Obstetrics and Gynecology, University of Duesseldorf, Medical Center, Duesseldorf, Germany
| | - P Dall
- Department of Obstetrics and Gynecology, University of Duesseldorf, Medical Center, Duesseldorf, Germany
| | - DT Curiel
- Division of Human Gene Therapy, Departments of Medicine, Surgery, Pathology and the Gene Therapy Center, University of Alabama at Birmingham, Birminham, AL, USA
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Noseda M, Niessen K, McLean G, Chang L, Karsan A. Notch-Dependent Cell Cycle Arrest Is Associated With Downregulation of Minichromosome Maintenance Proteins. Circ Res 2005; 97:102-4. [PMID: 15976316 DOI: 10.1161/01.res.0000174380.06673.81] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Perturbation of the Notch signaling pathway has been implicated in the pathogenesis of human cardiovascular diseases, and animal models have confirmed the requirement of Notch during cardiovascular development. We recently demonstrated that Notch activation delays S-phase entry and contributes to endothelial contact inhibition. Minichromosome maintenance (MCM) proteins, components of the prereplicative complex (pre-RC), are essential for DNA replication. Here, we report that Notch-mediated cell cycle arrest is associated with downregulation of MCM2 and MCM6 in endothelial cells and human fibroblasts. Downregulation of MCM proteins is also observed on activation of C promoter binding factor (CBF1) and is mediated by inhibition of Rb phosphorylation, as demonstrated using a constitutively active Rb mutant. Although the effects of the Notch pathway are cell-type specific and context-dependent, in cell types where Notch has an antiproliferative effect, downregulation of MCM proteins may be a common mechanism to inhibit DNA replication.
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Affiliation(s)
- Michela Noseda
- Department of Medical Biophysics, British Columbia Cancer Agency, Vancouver, Canada
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Chen PL, Liu F, Cai S, Lin X, Li A, Chen Y, Gu B, Lee EYHP, Lee WH. Inactivation of CtIP leads to early embryonic lethality mediated by G1 restraint and to tumorigenesis by haploid insufficiency. Mol Cell Biol 2005; 25:3535-42. [PMID: 15831459 PMCID: PMC1084307 DOI: 10.1128/mcb.25.9.3535-3542.2005] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Revised: 12/25/2004] [Accepted: 02/03/2005] [Indexed: 11/20/2022] Open
Abstract
CtIP interacts with a group of tumor suppressor proteins including RB (retinoblastoma protein), BRCA1, Ikaros, and CtBP, which regulate cell cycle progression through transcriptional repression as well as chromatin remodeling. However, how CtIP exerts its biological function in cell cycle progression remains elusive. To address this issue, we generated an inactivated Ctip allele in mice by inserting a neo gene into exon 5. The corresponding Ctip(-/-) embryos died at embryonic day 4.0 (E4.0), and the blastocysts failed to enter S phase but accumulated in G(1), leading to a slightly elevated cell death. Mouse NIH 3T3 cells depleted of Ctip were arrested at G(1) with the concomitant increase in hypophosphorylated Rb and Cdk inhibitors, p21. However, depletion of Ctip failed to arrest Rb(-/-) mouse embryonic fibroblasts (MEF) or human osteosarcoma Saos-2 cells at G(1), suggesting that this arrest is RB dependent. Importantly, the life span of Ctip(+/-) heterozygotes was shortened by the development of multiple types of tumors, predominantly, large lymphomas. The wild-type Ctip allele and protein remained detectable in these tumors, suggesting that haploid insufficiency of Ctip leads to tumorigenesis. Taken together, this finding uncovers a novel G(1)/S regulation in that CtIP counteracts Rb-mediated G(1) restraint. Deregulation of this function leads to a defect in early embryogenesis and contributes, in part, to tumor formation.
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Affiliation(s)
- Phang-Lang Chen
- Department of Biological Chemistry, College of Medicine, University of California-Irvine, Sprague Hall, Room 124, Irvine, CA 92697, USA
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St-Pierre B, Liu X, Kha LCT, Zhu X, Ryan O, Jiang Z, Zacksenhaus E. Conserved and specific functions of mammalian ssu72. Nucleic Acids Res 2005; 33:464-77. [PMID: 15659578 PMCID: PMC548335 DOI: 10.1093/nar/gki171] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We describe the cloning and characterization of a human homolog of the yeast transcription/RNA-processing factor Ssu72, following a yeast two-hybrid screen for pRb-binding factors in the prostate gland. Interaction between hSsu72 and pRb was observed in transfected mammalian cells and involved multiple domains in pRb; however, so far, mutual effects of these two factors could not be demonstrated. Like the yeast counterpart, mammalian Ssu72 associates with TFIIB and the yeast cleavage/polyadenylation factor Pta1, and exhibits intrinsic phosphatase activity. Mammals contain a single ssu72 gene and a few pseudogenes. During mouse embryogenesis, ssu72 was highly expressed in the nervous system and intestine; high expression in the nervous system persisted in adult mice and was also readily observed in multiple human tumor cell lines. Both endogenous and ectopically expressed mammalian Ssu72 proteins resided primarily in the cytoplasm and only partly in the nucleus. Interestingly, fusion to a strong nuclear localization signal conferred nuclear localization only in a fraction of transfected cells, suggesting active tethering in the cytoplasm. Suppression of ssu72 expression in mammalian cells by siRNA did not reduce proliferation/survival, and its over-expression did not affect transcription of candidate genes in transient reporter assays. Despite high conservation, hssu72 was unable to rescue an ssu72 lethal mutation in yeast. Together, our results highlight conserved and mammalian specific characteristics of mammalian ssu72.
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Affiliation(s)
- Benoit St-Pierre
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
| | - Xudong Liu
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
| | - Lan-Chau T. Kha
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
- Department of Medical Biophysics, University of TorontoToronto, Ontario, Canada M5G 2M1
| | - Xudong Zhu
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
| | - Owen Ryan
- Banting and Best Department of Medical ResearchToronto, Ontario, Canada M5G 1L6
| | - Zhe Jiang
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
| | - Eldad Zacksenhaus
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network67 College Street, Room 407, Toronto, Ontario, Canada M5G 2m1
- Department of Medicine, University of TorontoToronto, Ontario, Canada M5G 2M1
- Department of Laboratory Medicine and Pathobiology, University of TorontoToronto, Ontario, Canada M5G 2M1
- Department of Medical Biophysics, University of TorontoToronto, Ontario, Canada M5G 2M1
- To whom correspondence should be addressed. Tel: +1 416 340 4800 ext. 5106; Fax: +1 416 340 3453;
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37
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Affiliation(s)
- Suzanne J Baker
- Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
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38
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Ho AT, Li QH, Hakem R, Mak TW, Zacksenhaus E. Coupling of caspase-9 to Apaf1 in response to loss of pRb or cytotoxic drugs is cell-type-specific. EMBO J 2004; 23:460-72. [PMID: 14713951 PMCID: PMC1271749 DOI: 10.1038/sj.emboj.7600039] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2003] [Accepted: 11/20/2003] [Indexed: 12/27/2022] Open
Abstract
Inactivation of the tumor suppressor Rb in the mouse induces cell death, which depends entirely (in lens, CNS) and only partly (PNS, skeletal muscles) on Apaf1/Ced4, an apoptosomal factor thought to be required for processing procaspase-9 following mitochondrial permeabilization. Here, we report that in response to cytotoxic drugs, Apaf1(-/-) primary myoblasts but not fibroblasts undergo bona fide apoptosis. Cell demise was associated with disruption of mitochondria but not endoplasmic reticulum. Processing of procaspase-9 occurred in Apaf1(-/-) myoblasts but not fibroblasts, and ablation of Casp9 prevented drug-induced apoptosis in both cell types. Deregulation of the Rb pathway by overexpression of E2F1 also induced caspase-9-dependent, Apaf1-independent apoptosis in myoblasts. Despite its requirement for apoptosis in vitro, mutation in Casp9 abrogated cell death in the nervous system and lens but only partly in skeletal muscles of Rb-deficient embryos. In addition, developmental cell death in fetal liver and PNS was not inhibited in Casp9(-/-) embryos. Therefore, loss of pRb elicits apoptosome-dependent and apoptosome-independent cell death, and the requirement and coupling of caspase-9 to Apaf1 are both context-dependent.
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Affiliation(s)
- Andrew T Ho
- Departments of Medicine, Laboratory Medicine & Pathobiology and Medical Biophysics, Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Qin H Li
- Departments of Medicine, Laboratory Medicine & Pathobiology and Medical Biophysics, Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Razqallah Hakem
- Department of Medical Biophysics and Immunology, Advanced Medical Discovery Institute, University of Toronto, Toronto, Ontario, Canada
| | - Tak W Mak
- Department of Medical Biophysics and Immunology, Advanced Medical Discovery Institute, University of Toronto, Toronto, Ontario, Canada
| | - Eldad Zacksenhaus
- Departments of Medicine, Laboratory Medicine & Pathobiology and Medical Biophysics, Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Departments of Medicine, Laboratory Medicine & Pathobiology and Medical Biophysics, Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, 67 College Street, Toronto, Ontario, Canada M5G 2M1. Tel.: +1 416 340 4800 x 5106; Fax: +1 416 340 3453; E-mail:
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Huang H, Zegarra-Moro OL, Benson D, Tindall DJ. Androgens repress Bcl-2 expression via activation of the retinoblastoma (RB) protein in prostate cancer cells. Oncogene 2003; 23:2161-76. [PMID: 14676836 DOI: 10.1038/sj.onc.1207326] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The oncogene Bcl-2 is upregulated frequently in prostate tumors following androgen ablation therapy, and Bcl-2 overexpression may contribute to the androgen-refractory relapse of the disease. However, the molecular mechanism underlying androgenic regulation of Bcl-2 in prostate cancer cells is understood poorly. In this study, we demonstrated that no androgen response element (ARE) was identified in the androgen-regulated region of the P1 promoter of Bcl-2 gene, whereas, we provided evidence that the androgenic effect is mediated by E2F1 protein through a putative E2F-binding site in the promoter. We further demonstrated that retinoblastoma (RB) protein plays a critical role in androgen regulation of Bcl-2. The phosphorylation levels of RB at serine residues 780 and 795 were decreased in LNCaP cells treated with androgens. Ectopic expression of a constitutively active form of RB inhibited expression of Bcl-2. Knockdown of endogenous RB protein by an Rb small inference RNA (siRNA) induced an increase in Bcl-2 levels. Most importantly, the effect of androgens on Bcl-2 was abolished completely by specific inhibition of RB function with a mutated E1A. Finally, androgen treatment of LNCaP cells upregulated specifically levels of the cyclin-dependent kinase inhibitors (CDKIs) p15INK4B and p27KIP1. Ectopic expression of p15INK4B and/or p27KIP1 inhibited Bcl-2 expression. Knockdown of endogenous p15INK4B or p27KIP1 protein with a pool of siRNAs diminished androgen-induced downregulation of Bcl-2 expression. Therefore, our data indicate that androgens suppress Bcl-2 expression through negatively modulating activities of the E2F site in the Bcl-2 promoter by activating the CDKI-RB axis.
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Affiliation(s)
- Haojie Huang
- Department of Urology, Mayo Clinic/Foundation, Rochester, MN 55905, USA
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40
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Davison EA, Lee CSL, Naylor MJ, Oakes SR, Sutherland RL, Hennighausen L, Ormandy CJ, Musgrove EA. The cyclin-dependent kinase inhibitor p27 (Kip1) regulates both DNA synthesis and apoptosis in mammary epithelium but is not required for its functional development during pregnancy. Mol Endocrinol 2003; 17:2436-47. [PMID: 12933906 DOI: 10.1210/me.2003-0199] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Decreased expression of the cyclin-dependent kinase (CDK) inhibitor p27(Kip1) is common in breast cancer and is associated with poor prognosis. p27 is also an important mediator of steroidal regulation of cell cycle progression. We have therefore investigated the role of p27 in mammary epithelial cell proliferation. Examination of the two major functions of p27, assembly of cyclin D1-Cdk4 complexes and inhibition of Cdk2 activity, revealed that cyclin D1-Cdk4 complex formation was not impaired in p27-/- mammary epithelial cells in primary culture. However, cyclin E-Cdk2 activity was increased approximately 3-fold, indicating that the CDK inhibitory function of p27 is important in mammary epithelial cells. Increased epithelial DNA synthesis was observed during pregnancy in p27-/- mammary gland transplants, but this was paralleled by increased apoptosis. During pregnancy and at parturition, development and differentiation of p27+/+ and p27-/- mammary tissue were indistinguishable. These results demonstrate a role for p27 in both the proliferation and survival of mammary epithelial cells. However, the absence of morphological and cellular defects in p27-/- mammary tissue during pregnancy raises the possibility that loss of p27 in breast cancer may not confer an overall growth advantage unless apoptosis is also impaired.
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Affiliation(s)
- Elizabeth A Davison
- Cancer Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Australia
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41
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Goodrich DW. How the other half lives, the amino-terminal domain of the retinoblastoma tumor suppressor protein. J Cell Physiol 2003; 197:169-80. [PMID: 14502556 DOI: 10.1002/jcp.10358] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The retinoblastoma tumor suppressor gene (RB1) is currently the only known gene whose mutation is necessary and sufficient for the development of a human cancer. Mutation or deregulation of RB1 is observed so frequently in other tumor types that compromising RB1 function may be a prerequisite for malignant transformation. Identifying the molecular mechanisms that provide the basis for RB1-mediated tumor suppression has become an important goal in the quest to understand and treat cancer. The lion's share of research on these mechanisms has focused on the carboxy-terminal half of the RB1 encoded protein (pRB). This focus is with good reason since this part of the protein, now called the "large pocket," is required for most of its known activities identified in vitro and in vivo. Large pocket mediated mechanisms alone, however, cannot account for all observed properties of pRB. The thesis presented here is that the relatively uncharacterized amino-terminal half of the protein makes important contributions to pRB-mediated tumor suppression. The goals of this review are to summarize evidence indicating that an amino-terminal structural domain is important for pRB function and to suggest a general hypothesis as to how this domain can be integrated with current models of pRB function.
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Affiliation(s)
- David W Goodrich
- Department of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, New York 14263, USA.
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42
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Abstract
PURPOSE OF REVIEW Over the past 10 years, the treatment of retinoblastoma has changed dramatically. The main impetus for these changes, which are more intensive than traditional modalities and require a multidisciplinary approach, has been the avoidance of the serious, often fatal, complications of external beam radiation. The use of potent, well known chemotherapy agents in a novel setting (ie, intraocular tumor) has been successful in treating all but the most advanced disease. RECENT FINDINGS This review will examine recent published work with chemotherapy and local (focal laser) treatment for intraocular (curable) retinoblastoma. Specifically, the concepts behind and the practice of chemoreduction and thermochemotherapy and their efficacies will be evaluated. SUMMARY The work discussed herein constitutes an extremely nascent and dynamic field of work in ocular oncology. Much uncertainty remains, especially as most of these patients will live for many decades after their presentation and treatment. The review will show that a significant number of treatment failures still occur and that continued work is needed before we can feel confident treating young patients with all forms of this rare tumor.
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Milde-Langosch K, Riethdorf S. Role of cell-cycle regulatory proteins in gynecological cancer. J Cell Physiol 2003; 196:224-44. [PMID: 12811815 DOI: 10.1002/jcp.10286] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Human malignant tumors are characterized by abnormal proliferation resulting from alterations in cell-cycle regulatory mechanisms. This review summarizes the current knowledge about these aberrations in malignant tumors of the ovary, endometrium, cervix uteri, and vulva. The data indicate that analysis of single cell cycle stimulating or inhibiting proteins partly produces unexpected, apparently paradoxical results, and cell-cycle regulatory pathways should be regarded as a whole in order to identify the molecular mechanisms leading to abnormal tumor cell proliferation. For the papillomavirus (HPV)- associated cervical and vulvar carcinomas, the manifold effects of the viral oncogenes E6 and E7 on cell-cycle control are described.
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Affiliation(s)
- Karin Milde-Langosch
- Institute of Pathology, Department of Gynecopathology, University Clinics Hamburg-Eppendorf, Hamburg, Germany.
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Balasenthil S, Vadlamudi RK. Functional interactions between the estrogen receptor coactivator PELP1/MNAR and retinoblastoma protein. J Biol Chem 2003; 278:22119-27. [PMID: 12682072 PMCID: PMC1262660 DOI: 10.1074/jbc.m212822200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PELP1 (proline-, glutamic acid-, and leucine-rich protein-1 (also referred to as MNAR, or modulator of nongenomic activity of estrogen receptor)), a recently identified novel coactivator of estrogen receptors, is widely expressed in a variety of 17 beta-estradiol (E2)-responsive reproductive tissues and is developmentally regulated in mammary glands. pRb (retinoblastoma protein), a cell cycle switch protein, plays a fundamental role in the proliferation, development, and differentiation of eukaryotic cells. To study the putative function of PELP1, we established stable MCF-7 breast cancer cell lines overexpressing PELP1. PELP1 overexpression hypersensitized breast cancer cells to E2 signaling, enhanced progression of breast cancer cells to S phase, and led to persistent hyperphosphorylation of pRb in an E2-dependent manner. Using phosphorylation site-specific pRb antibodies, we identified Ser-807/Ser-811 of pRb as a potential target site of PELP1. Interestingly, PELP1 was discovered to be physiologically associated with pRb and interacted via its C-terminal pocket domain, and PELP1/pRb interaction could be modulated by antiestrogen agents. Using mutant pRb cells, we demonstrated an essential role for PELP1/pRb interactions in the maximal coactivation functions of PELP1 using cyclin D1 as one of the targets. Taken together, these findings suggest that PELP1, a steroid coactivator, plays a permissive role in E2-mediated cell cycle progression, presumably via its regulatory interaction with the pRb pathway.
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Affiliation(s)
| | - Ratna K. Vadlamudi
- ‡ To whom correspondence should be addressed: Dept. of Molecular and Cellular Oncology, Unit 108, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030. Tel.: 713-745-5239; Fax: 713-745-2050; E-mail:
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45
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Abstract
Recent studies have shown that RB can inhibit apoptosis, independently of its ability to block cell proliferation. This poses the question of how cells choose to grow or to die when RB becomes inactivated. RB is phosphorylated following mitogenic stimulation, but it is degraded in response to death stimuli. Most sporadic cancers also inactivate RB by phosphorylation, rather than losing RB entirely--possibly to exploit the survival advantage conferred by RB under stress. Drawing from the different mechanisms of RB inactivation, we propose two models for ways in which cells use RB to make the choice of life versus death.
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Affiliation(s)
- B Nelson Chau
- Division of Biological Sciences and the Cancer Center, University of California, San Diego, La Jolla, California 92093-0322, USA
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46
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Abstract
Apart from their coordinated inactivation by DNA tumor viral oncoproteins, the pRB and p53 tumor suppressor pathways were not known to be connected ten years ago. Within the last decade, our appreciation of how these pathways are interconnected has grown substantially. The checks and balances that exist between pRB and p53 involve the regulation of the G1/S transition and its checkpoints, and much of this is under the control of the E2F transcription factor family. Following DNA damage, the p53-dependent induction of p21CIP1 regulates cyclin E/Cdk2 and cyclin A/Cdk2 complexes both of which phosphorylate pRB, leading to E2F-mediated activation. Similarly, E2F1-dependent induction of p19ARF antagonizes the ability of mdm2 to degrade p53, leading to p53 stabilization and potentially p53-mediated apoptosis or cell cycle arrest. From the existing mouse models discussed above, we also know that proliferation, cell death and differentiation of distinct tissues are also intimately linked through entrance and exit from the cell cycle, and thus through pRB and p53 pathways. Virtually all human tumors deregulate either the pRB or p53 pathway, and often times both pathways simultaneously, which is critical for crippling cellular defense against neoplasia. The next decade of cancer research will likely see these two tumor suppressor pathways only merge even more.
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47
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Abstract
Since its discovery, the retinoblastoma (RB) tumour-suppressor protein has been a focal point of cancer research. Accumulating evidence indicates a complex role for RB in cell proliferation, differentiation and survival. To further complicate matters, proteins that are related to RB have redundant as well as antagonistic functions. Recent studies of knockout mice and cells that lack one or more of these proteins have begun to clarify their various context-specific functions and the unique activity of this tumour suppressor.
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Affiliation(s)
- Marie Classon
- MGH Cancer Center, Building 149, 13th Street, Room 7330, Charlestown, Massachusetts 02129, USA.
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