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Sundararajan V, Tan TZ, Lim D, Peng Y, Wengner AM, Ngoi NYL, Jeyasekharan AD, Tan DSP. Nuclear pCHK1 as a potential biomarker of increased sensitivity to ATR inhibition. J Pathol 2023; 259:194-204. [PMID: 36373784 PMCID: PMC10107453 DOI: 10.1002/path.6032] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 10/28/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022]
Abstract
Excessive genomic instability coupled with abnormalities in DNA repair pathways induces high levels of 'replication stress' when cancer cells propagate. Rather than hampering cancer cell proliferation, novel treatment strategies are turning their attention towards targeting cell cycle checkpoint kinases (such as ATR, CHK1, WEE1, and others) along the DNA damage response and replicative stress response pathways, thereby allowing unrepaired DNA damage to be carried forward towards mitotic catastrophe and apoptosis. The selective ATR kinase inhibitor elimusertib (BAY 1895344) has demonstrated preclinical and clinical monotherapy activity; however, reliable predictive biomarkers of treatment benefit are still lacking. In this study, using gene expression profiling of 24 cell lines from different cancer types and in a panel of ovarian cancer cell lines, we found that nuclear-specific enrichment of checkpoint kinase 1 (CHK1) correlated with increased sensitivity to elimusertib. Using an advanced multispectral imaging system in subsequent cell line-derived xenograft specimens, we showed a trend between nuclear phosphorylated CHK1 (pCHK1) staining and increased sensitivity to the ATR inhibitor elimusertib, indicating the potential value of pCHK1 expression as a predictive biomarker of ATR inhibitor sensitivity. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Vignesh Sundararajan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Tuan Zea Tan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,Genomics and Data Analytics Core (GeDaC), Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Diana Lim
- Department of Pathology, National University Hospital, Singapore, Singapore
| | - Yanfen Peng
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | | | - Natalie Yan Li Ngoi
- Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
| | - Anand D Jeyasekharan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - David Shao Peng Tan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
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Zhao X, Zhang X, Shao S, Yang Q, Shen C, Yang X, Jiao W, Liu J, Wang Y. High expression of GMNN predicts malignant progression and poor prognosis in ACC. Eur J Med Res 2022; 27:301. [PMID: 36539849 PMCID: PMC9764478 DOI: 10.1186/s40001-022-00950-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Adrenocortical carcinoma (ACC) is a rare endocrine neoplasm, which is characterized by poor prognosis and high recurrence rate. Novel and reliable prognostic and metastatic biomarkers are lacking for ACC patients. This study aims at screening potential prognostic biomarkers and therapeutic targets of ACC through bioinformatic methods and immunohistochemical (IHC) analysis. METHODS In the present study, by using the Gene Expression Omnibus (GEO) database we identified differentially expressed genes (DEGs) in ACC and validated these DEGs in The Cancer Genome Atlas (TCGA) ACC cohort. A DEGs-based signature was additionally constructed and we assessed its prognosis and prescient worth for ACC by survival analysis and nomogram. Immunohistochemistry (IHC) was used to verify the relationship between hub gene-GMNN expressions and clinicopathologic outcomes in ACC patients. RESULTS A total of 24 DEGs correlated with the prognosis of ACC were screened from the TCGA and GEO databases. Five DEGs were subsequently selected in a signature which was closely related to the survival rates of ACC patients and GMNN was identified as the core gene in this signature. Univariate and multivariate Cox regression showed that the GMNN was an independent prognostic factor for ACC patients (P < 0.05). Meanwhile, GMNN was closely related to the OS and PFI of ACC patients treated with mitotane (P < 0.001). IHC confirmed that GMNN protein was overexpressed in ACC tissues compared with normal adrenal tissues and significantly correlated with stage (P = 0.011), metastasis (P = 0.028) and Ki-67 index (P = 0.014). CONCLUSIONS GMNN is a novel tumor marker for predicting the malignant progression, metastasis and prognosis of ACC, and may be a potential therapeutic target for ACC.
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Affiliation(s)
- Xinzhao Zhao
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Xuezhou Zhang
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Shixiu Shao
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Qingbo Yang
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Chengquan Shen
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Xuecheng Yang
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Wei Jiao
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Jing Liu
- grid.412521.10000 0004 1769 1119Department of Research Management and International Cooperation, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
| | - Yonghua Wang
- grid.412521.10000 0004 1769 1119Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong China
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3
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Etemad-Moghadam S, Mohammadpour H, Alaeddini M. Distinctive expression of DNA replication factors in squamous cell carcinomas of the lip, face and oral cavity. JOURNAL OF STOMATOLOGY, ORAL AND MAXILLOFACIAL SURGERY 2022; 123:e828-e832. [PMID: 35217222 DOI: 10.1016/j.jormas.2022.02.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/09/2022] [Accepted: 02/21/2022] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Uncontrolled proliferation and aberrations in cell-cycle progression are fundamental issues in cancer. In this study we aimed to determine and compare deoxyribonucleic acid (DNA) replication licensing factors at the mRNA and protein levels among squamous cell carcinomas (SCCs) of the lip, facial-skin and oral cavity. MATERIALS AND METHODS A total of 103 lip, oral and face SCCs were immunohistochemically stained with MCM2 (mini-chromosome maintenance 2), geminin, and ki67, and their labeling-indices were calculated. Also, 57 SCCs from the same regions along with their adjacent normal tissues underwent quantitative reverse transcription-polymerase chain reaction analysis. RESULTS All three proteins were overexpressed in the studied SCCs, but only geminin (P = 0.004) showed significant difference among the three regions, with higher levels in oral SCCs compared to lip (P = 0.005) and skin (P = 0.024) tumors. Geminin expression did not differ between skin- and lip-SCCs (P = 0.822). MCM2/ki67 ratio was higher in oral- compared to skin-neoplasms (P = 0.039), but no difference was found in geminin/ki67 among the SCC-subsites. There were significant differences in MCM2 and geminin mRNA between carcinomatous- and normal-tissues in all tumors, but not among the three locations. CONCLUSION MCM2 and geminin are involved in the tumorigenesis of lip, face and oral SCC at both mRNA- and protein-levels. Geminin may have a role in the site-specific biologic behavior of SCC. Skin SCCs had the highest proportion of licensed non-proliferating cells, while actively proliferating cells were more prominent in oral tumors. Regarding DNA replication, lip SCCs seem to be closer to skin tumors compared to their oral counterparts.
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Affiliation(s)
- Shahroo Etemad-Moghadam
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Ghods St, Enghelab Ave, P.O. Box: 14155-5583, Tehran 14174, Iran
| | - Hadiseh Mohammadpour
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Ghods St, Enghelab Ave, P.O. Box: 14155-5583, Tehran 14174, Iran
| | - Mojgan Alaeddini
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Ghods St, Enghelab Ave, P.O. Box: 14155-5583, Tehran 14174, Iran.
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4
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Etemad-Moghadam S, Ghaseminejad-Bandpey A, Mahmoodzadeh H, Alaeddini M. Clinicopathologic significance of DNA replication licensing factors in head and neck diffuse large B-cell lymphoma. Oral Surg Oral Med Oral Pathol Oral Radiol 2022; 133:462-469. [PMID: 35153182 DOI: 10.1016/j.oooo.2021.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 09/13/2021] [Accepted: 10/22/2021] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Diffuse large B-cell lymphoma (DLBCL) harbors defects in the proliferation pathway. We performed multiparameter analysis of proteins expressed during different cell cycle phases and correlated them with clinical parameters of head and neck DLBCLs. STUDY DESIGN Thirty-nine DLBCLs were staged and immunohistochemically stained with MCM2, Ki67, and geminin. The receiver operating characteristic curve and its area under the curve were calculated, and sensitivity vs specificity curve analysis was performed. RESULTS The highest labeling index was in MCM2, followed by Ki67 and geminin (P < .001). All pairs showed significant differences (P < .001). The best cutoff points to differentiate limited from advanced disease were 68% and 45% for MCM2 and Ki67, respectively. There was no acceptable cutoff for geminin (area under the curve = 0.667, P = .134). MCM2/Ki67 (P = .293) and geminin/Ki67 (P = .233) ratios did not differ between the stages. The median (interquartile range) of the geminin/Ki67 ratio was 0.57 (0.68), translating to a reduced G1. CONCLUSIONS We suggest a role for cell cycle-related proteins in the biology and behavior of DLBCLs. MCM2 and Ki67 cutoffs can be a potential option to differentiate limited from advanced disease, where imaging and laboratory techniques are unavailable. The G1 decrease and the significantly higher MCM2 expression compared to Ki67 indicate replication disturbances, making factors involved in the G1 phase targets for treatment.
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Affiliation(s)
| | | | - Habibollah Mahmoodzadeh
- Division of Surgical Oncology, Department of Surgery, Cancer Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Mojgan Alaeddini
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences.
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5
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Alaeddini M, Etemad-Moghadam S. Cell kinetic markers in cutaneous squamous and basal cell carcinoma of the head and neck. Braz J Otorhinolaryngol 2020; 88:529-532. [PMID: 32972865 PMCID: PMC9422672 DOI: 10.1016/j.bjorl.2020.07.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 05/28/2020] [Accepted: 07/13/2020] [Indexed: 11/24/2022] Open
Abstract
Introduction Proliferation markers play a significant role in the biologic behavior of tumors. Geminin is a known inhibitor of the cell cycle and DNA replication and has not been previously reported in cutaneous basal and squamous cell carcinomas of the head and neck. Objectives We aimed to investigate proliferation markers ki67, MCM2, and geminin in head and neck cutaneous basal and squamous cell carcinomas. Methods Forty cases of each tumor were immuostained with ki67, MCM2, and geminin followed by assessment of labeling indices (LIs). MCM2/ki67- and geminin/ki67-ratios were also determined; t-test was used for statistical analysis (p < 0.05). Results There was no significant difference in ki67 (p = 0.06) and MCM2 (p = 0.46) between cutaneous basal and squamous cell carcinomas; however, geminin LI was significantly higher in squamous cell carcinomas compared to cutaneous basal cell carcinomas (p < 0.001). Only geminin/ki67 showed a significant difference between the two tumors with the ratio showing significantly higher numbers in squamous cell carcinomas (p = 0.015). Conclusions Geminin could be regarded as an effective factor in the pathogenesis of head and neck cutaneous cutaneous basal cell carcinomas and squamous cell carcinomas and may be one of the responsible elements in the difference between the biologic behavior of these tumors.
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Affiliation(s)
- Mojgan Alaeddini
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Shahroo Etemad-Moghadam
- Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
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6
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Cheng L, Tan Z, Huang Z, Pan Y, Zhang W, Wang J. Expression Profile and Prognostic Values of Mini-Chromosome Maintenance Families (MCMs) in Breast Cancer. Med Sci Monit 2020; 26:e923673. [PMID: 32830194 PMCID: PMC7461652 DOI: 10.12659/msm.923673] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Background Mini-chromosome maintenance families (MCMs) were considered the key factors for DNA replication initiation. Emerging evidences indicate that MCM2-7 (MCMs) are highly expressed in tissues from various malignant tumors. However, little is known about the clinical values of MCMs in breast cancer. Material/Methods In our study, a comprehensive bioinformatics analysis was performed to investigate expression patterns, potential functions, and prognostic values of MCMs in breast cancer, through ONCOMINE, bc-GenExMiner v4.1, Kaplan-Meier Plotter, cBioPortal and GeneMANIA databases. Results We found that mRNA levels of MCMs were significantly elevated in breast cancer, especially in fast-growing and spreading tumor subtypes. These over-expressed MCMs predicted worse prognosis for breast cancer patients with shorter relapse-free survival (RFS) and overall survival. Among these six factors, high expression of MCM2/4/5/7 significantly reduced the RFS for patients with Luminal-A or B breast cancer and elevated MCM6/7 indicated shorter RFS for patients with basal-like or HER2-positive breast cancer. We also found that genomic alteration of MCMs was frequently found in breast cancer and the most common alteration was mRNA upregulation and amplification. Furthermore, MCMs were highly correlated with CDC45, CDC7, TIMELESS, ORC6, MCM10, ORC5, ORC4 and ORC3, mainly functioning to control the DNA replication initiation and genome stability. Conclusions These results suggest that MCMs are attractive prognostic biomarkers for breast cancer. Our study also provides useful clinical information about the potential of MCMs as therapeutic targets.
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Affiliation(s)
- Lin Cheng
- Department of Breast and Thyroid Surgery, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China (mainland)
| | - Zhangmin Tan
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Zenan Huang
- Department of Breast and Thyroid Surgery, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China (mainland)
| | - Yuhang Pan
- Department of Pathology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Wenhui Zhang
- Department of Joint Surgery and Orthopedic Trauma, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China (mainland)
| | - Jiani Wang
- Department of Breast and Thyroid Surgery, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China (mainland)
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7
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Nasri Nasrabadi P, Nayeri Z, Gharib E, Salmanipour R, Masoomi F, Mahjoubi F, Zomorodipour A. Establishment of a CALU, AURKA, and MCM2 gene panel for discrimination of metastasis from primary colon and lung cancers. PLoS One 2020; 15:e0233717. [PMID: 32469983 PMCID: PMC7259615 DOI: 10.1371/journal.pone.0233717] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 05/11/2020] [Indexed: 12/15/2022] Open
Abstract
Metastasis is known as a key step in cancer recurrence and could be stimulated by multiple factors. Calumenin (CALU) is one of these factors which has a direct impact on cancer metastasis and yet, its underlined mechanisms have not been completely elucidated. The current study was aimed to identify CALU co-expressed genes, their signaling pathways, and expression status within the human cancers. To this point, CALU associated genes were visualized using the Cytoscape plugin BisoGenet and annotated with the Enrichr web-based application. The list of CALU related diseases was retrieved using the DisGenNet, and cancer datasets were downloaded from The Cancer Genome Atlas (TCGA) and analyzed with the Cufflink software. ROC curve analysis was used to estimate the diagnostic accuracy of DEGs in each cancer, and the Kaplan–Meier survival analysis was performed to plot the overall survival of patients. The protein level of the signature biomarkers was measured in 40 biopsy specimens and matched adjacent normal tissues collected from CRC and lung cancer patients. Analysis of CALU co-expressed genes network in TCGA datasets indicated that the network is markedly altered in human colon (COAD) and lung (LUAD) cancers. Diagnostic accuracy estimation of differentially expressed genes showed that a gene panel consisted of CALU, AURKA, and MCM2 was able to successfully distinguish cancer tumors from healthy samples. Cancer cases with abnormal expression of the signature genes had a significantly lower survival rate than other patients. Additionally, comparison of CALU, AURKA, and MCM2 proteins between healthy samples, early and advanced tumors showed that the level of these proteins was increased through normal–carcinoma transition in both types of cancers. These data indicate that the interactions between CALU, AURKA, and MCM2 has a pivotal role in cancer development, and thereby needs to be explored in the future.
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Affiliation(s)
- Parinaz Nasri Nasrabadi
- Department of Molecular Medicine, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Zahra Nayeri
- Department of Molecular Medicine, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Ehsan Gharib
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Reza Salmanipour
- Department of Molecular Medicine, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Fatemeh Masoomi
- Department of Molecular Medicine, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Forouzandeh Mahjoubi
- Department of Medical Genetics, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Alireza Zomorodipour
- Department of Molecular Medicine, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
- * E-mail: ,
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8
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Al-Hazmi N, Alhazzazi T, Williams G, Stoeber K, Al-Dabbagh R. DNA replication licensing factor MCM2, geminin, and Ki67 define proliferative state and are linked with survival in oral squamous cell carcinoma. Eur J Oral Sci 2019; 126:186-196. [PMID: 29745471 DOI: 10.1111/eos.12420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Oral squamous cell carcinoma (OSCC) is still an unabated global killer with little advancement in its survival rate. DNA replication licensing proteins and Aurora kinase A are biomarkers that play important roles in genomic stability. The expression profile of minichromosomal maintenance protein 2 (MCM2), Ki67, geminin, and Aurora-A were linked to clinicopathological and outcome parameters, survival, and DNA content in 125 cases of OSCC. Oral fibroepithelial polyps (OFEP) were controls. The OSCC tumour cells were in a rapidly proliferating state, as assessed by the increased expression profile of MCM2, Ki67, geminin, and Aurora-A and of the geminin/Ki67 ratio, and the decrease of the MCM2/Ki67 ratio, in OSCC compared with OFEP (P < 0.000). There was an association between expression of MCM2, Ki67, and geminin and tumour histologic and invasive front grade (P < 0.05). A total of 82% of the OSCC assessed had aneuploid DNA content, which was associated with increased expression intensity of Aurora-A (P = 0.01). Geminin and the geminin/Ki67 ratio were associated with TNM staging (P < 0.05), and weak expression of MCM2, Ki67, geminin, and Aurora-A were predictive of OSCC survival (P < 0.05). Dysregulation of the origin licensing pathway and the mitotic pathway are important events in OSCC, and the combined analysis of these proteins may contribute to improved treatment decisions.
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Affiliation(s)
- Nadia Al-Hazmi
- Department of Oral Biology, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Turki Alhazzazi
- Department of Oral Biology, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Gareth Williams
- Oncologica, London, UK.,Department of Pathology, UCL Cancer Institute, University College London, London, UK
| | - Kai Stoeber
- Department of Pathology, UCL Cancer Institute, University College London, London, UK
| | - Raghad Al-Dabbagh
- Department of Oral and Maxillofacial Prosthodontics, King Abdulaziz University, Jeddah, Saudi Arabia
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Sellar RS, Gale RE, Khwaja A, Garbowski M, Loddo M, Stoeber K, Williams GH, Linch DC. Immunophenotypic analysis of cell cycle status in acute myeloid leukaemia: relationship to cytogenetics, genotype and clinical outcome. Br J Haematol 2018; 181:486-494. [PMID: 29676467 DOI: 10.1111/bjh.15211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/01/2018] [Indexed: 11/30/2022]
Abstract
Cell cycle status may play an important role in directing patient therapy. We therefore determined the cell cycle status of leukaemic cells by immunophenotypic analysis of bone marrow trephine biopsies from 181 patients with acute myeloid leukaemia (AML) and correlated the results with biological features and clinical outcome. There was considerable heterogeneity between patients. The presenting white cell count significantly correlated with the proportion of non-quiescent cells (P < 0·0001), of cycling cells beyond G1 (P < 0·0001) and the speed of cycling (P < 0·0001). Profiles in acute promyelocytic leukaemia (APL) differed from non-APL and were consistent with more differentiated cells with reduced proliferative potential, but no significant differences were observed between non-APL cytogenetic risk groups. NPM1 mutations but not FLT3 internal tandem duplication (FLT3ITD ) were significantly associated with a higher proportion of cells beyond G1 (P = 0·002) and faster speed of cycling (P = 0·003). Resistance to standard cytosine arabinoside and daunorubicin induction chemotherapy was significantly related to a slower speed of cycling (P = 0·0002), as was a higher relapse rate (P = 0·05), but not with the proportion of non-quiescent cells or actively cycling cells. These results show a link between the cycling speed of AML cells and the response to chemotherapy, and help to identify a group with a very poor prognosis.
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Affiliation(s)
- Rob S Sellar
- Department of Haematology, UCL Cancer Institute, London, UK
| | | | - Asim Khwaja
- Department of Haematology, UCL Cancer Institute, London, UK
| | | | - Marco Loddo
- Department of Pathology, UCL Cancer Institute, London, UK
| | - Kai Stoeber
- Department of Pathology, UCL Cancer Institute, London, UK.,Shinogi Ltd, London, UK
| | - Gareth H Williams
- Department of Pathology, UCL Cancer Institute, London, UK.,Oncologica Ltd, Cambridge, UK
| | - David C Linch
- Department of Haematology, UCL Cancer Institute, London, UK
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10
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Yousef EM, Furrer D, Laperriere DL, Tahir MR, Mader S, Diorio C, Gaboury LA. MCM2: An alternative to Ki-67 for measuring breast cancer cell proliferation. Mod Pathol 2017; 30:682-697. [PMID: 28084344 DOI: 10.1038/modpathol.2016.231] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 11/10/2022]
Abstract
Breast cancer is a heterogeneous disease comprising a diversity of tumor subtypes that manifest themselves in a wide variety of clinical, pathological, and molecular features. One important subset, luminal breast cancers, comprises two clinically distinct subtypes luminal A and B each of them endowed with its own genetic program of differentiation and proliferation. Luminal breast cancers were operationally defined as follows: Luminal A: ER+, PR+, HER2-, Ki-67<14% and Luminal B: ER+ and/or PR+, HER2-,Ki-67≥14% or, alternatively ER+ and/or PR+, HER2+, any Ki-67. There is currently a need for a clinically robust and validated immunohistochemical assay that can help distinguish between luminal A and B breast cancer. MCM2 is a family member of the minichromosome maintenance protein complex whose role in DNA replication and cell proliferation is firmly established. As MCM2 appears to be an attractive alternative to Ki-67, we sought to study the expression of MCM2 and Ki-67 in different histological grades and molecular subtypes of breast cancer focusing primarily on ER-positive tumors. MCM2 and Ki-67 mRNA expression were studied using in silico analysis of available DNA microarray and RNA-sequencing data of human breast cancer. We next used immunohistochemistry to evaluate protein expression of MCM2 and Ki-67 on tissue microarrays of invasive breast carcinoma. We found that MCM2 and Ki-67 are highly expressed in breast tumors of high histological grades, comprising clinically aggressive tumors such as triple-negative, HER2-positive and luminal B subtypes. MCM2 expression was detected at higher levels than that of Ki-67 in normal breast tissues and in breast cancers. The bimodal distribution of MCM2 scores in ER+/HER2- breast tumors led to the identification of two distinct subgroups with different relapse-free survival rates. In conclusion, MCM2 expression can help sorting out two clinically important subsets of luminal breast cancer whose treatment and clinical outcomes are likely to diverge.
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Affiliation(s)
- Einas M Yousef
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC, Canada.,Department of Histology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
| | - Daniela Furrer
- Cancer Research Centre at Laval University, Quebec City, QC, Canada.,Oncology Axis, CHU of Quebec Research Center, Hôpital du Saint-Sacrement, Quebec City, QC, Canada.,Department of Social and Preventive Medicine, Faculty of Medicine, Laval University, Quebec City, QC, Canada
| | - David L Laperriere
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC, Canada
| | - Muhammad R Tahir
- The University of Montreal Hospital Research Centre, Montreal, QC, Canada
| | - Sylvie Mader
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC, Canada.,Department of Biochemistry, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
| | - Caroline Diorio
- Cancer Research Centre at Laval University, Quebec City, QC, Canada.,Oncology Axis, CHU of Quebec Research Center, Hôpital du Saint-Sacrement, Quebec City, QC, Canada.,Department of Social and Preventive Medicine, Faculty of Medicine, Laval University, Quebec City, QC, Canada.,Deschênes-Fabia Center for Breast Diseases, Hôpital du St-Sacrement, Quebec City, QC, Canada
| | - Louis A Gaboury
- Institute for Research in Immunology and Cancer, University of Montreal, Montreal, QC, Canada.,Department of Pathology and Cell Biology, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
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11
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Zargoun IM, Bingle L, Speight PM. DNA ploidy and cell cycle protein expression in oral squamous cell carcinomas with and without lymph node metastases. J Oral Pathol Med 2017; 46:738-743. [PMID: 28135012 DOI: 10.1111/jop.12554] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2017] [Indexed: 01/24/2023]
Abstract
BACKGROUND Oral squamous cell carcinoma (OSCC) is the most frequently occurring malignant tumour in the oral cavity. OSCC arises because of multiple genetic alterations. Cell cycle aberrations and aneuploidy are reportedly among the main characteristics of cancer cells and are associated with aggressive growth and poor prognosis. METHODS The study sample included 47 non-metastasised and 39 metastasised primary OSCC, with matched positive cervical lymph nodes and 17 normal oral mucosa samples. Tissue microarrays (TMAs) were prepared with a minimum of three cores from each case. TMA sections were cut and immunostained with MCM2, Ki-67, geminin and cyclin D1 antibodies. DNA image analysis was performed on the whole tissue section before TMAs were created. RESULTS The results revealed that there were no differences in cell cycle protein expression in different areas of the tumours or between the metastatic and non-metastatic carcinomas. None of the cell cycle proteins showed significant differences between the lymph node metastasis and the primary OSCC, except for Ki-67. Geminin/Ki-67 ratio showed significant difference between metastatic and non-metastatic tumours. Aneuploidy was detected in all (100%) cases of OSCC. Similarly, all lymph node samples (39 cases) were aneuploid. CONCLUSION The results suggest that although there was dysregulation of cell cycle regulatory proteins, only Ki-67 and the MCM2/Ki-67 and geminin/Ki-67 ratios may have prognostic significance in oral cancer. DNA ploidy alone was not specific and may not be a good tool to evaluate prognosis or metastatic progression in oral cavity carcinomas.
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Affiliation(s)
- Ibtisam M Zargoun
- Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, UK
| | - L Bingle
- Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, UK
| | - P M Speight
- Oral and Maxillofacial Pathology, School of Clinical Dentistry, University of Sheffield, Sheffield, UK
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Tudzarova S, Mulholland P, Dey A, Stoeber K, Okorokov AL, Williams GH. p53 controls CDC7 levels to reinforce G1 cell cycle arrest upon genotoxic stress. Cell Cycle 2016; 15:2958-2972. [PMID: 27611229 PMCID: PMC5105930 DOI: 10.1080/15384101.2016.1231281] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
DNA replication initiation is a key event in the cell cycle, which is dependent on 2 kinases - CDK2 and CDC7. Here we report a novel mechanism in which p53 induces G1 checkpoint and cell cycle arrest by downregulating CDC7 kinase in response to genotoxic stress. We demonstrate that p53 controls CDC7 stability post-transcriptionally via miR-192/215 and post-translationally via Fbxw7β E3 ubiquitin ligase. The p53-dependent pathway of CDC7 downregulation is interlinked with the p53-p21-CDK2 pathway, as p21-mediated inhibition of CDK2-dependent phosphorylation of CDC7 on Thr376 is required for GSK3ß-phosphorylation and Fbxw7ß-dependent degradation of CDC7. Notably, sustained oncogenic high levels of active CDC7 exert a negative feedback onto p53, leading to unrestrained S-phase progression and accumulation of DNA damage. Thus, p53-dependent control of CDC7 levels is essential for blocking G1/S cell-cycle transition upon genotoxic stress, thereby safeguarding the genome from instability and thus representing a novel general stress response.
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Affiliation(s)
- Slavica Tudzarova
- a Wolfson Institute for Biomedical Research, Division of Medicine, University College London , London , UK.,b Division of Endocrinology, David Geffen School of Medicine, University of California Los Angeles , Los Angeles , CA , USA
| | - Paul Mulholland
- c Department of Pathology , UCL Cancer Institute, University College London , London , UK
| | - Ayona Dey
- a Wolfson Institute for Biomedical Research, Division of Medicine, University College London , London , UK
| | - Kai Stoeber
- c Department of Pathology , UCL Cancer Institute, University College London , London , UK
| | - Andrei L Okorokov
- a Wolfson Institute for Biomedical Research, Division of Medicine, University College London , London , UK
| | - Gareth H Williams
- c Department of Pathology , UCL Cancer Institute, University College London , London , UK.,d Oncologica Ltd, The Science Village, Chesterford Research Park , Cambridge , UK
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Atalay T, Ak H, Celik B, Gulsen I, Seckin H, Tanik N, Albayrak SB, Bavbek M. Prognostic Factors in Oligodendrogliomas: a Clinical Study of Twenty-Five Consecutive Patients. Asian Pac J Cancer Prev 2015. [PMID: 26225672 DOI: 10.7314/apjcp.2015.16.13.5319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The purpose of this study was to evaluate the prognostic significance of Ki-67 and subjective microvascular density (SMVD) indexes together with other factors in patients with oligodendroglioma. MATERIALS AND METHODS In this retrospective study, oligodendroglioma specimens obtained from twenty-five consecutive patients were evaluated for Ki-67 and SMVD indices to help determine histological grading and investigate the fidelity of these markers in clinical prognosis. Other potentially prognostic factors were Karnofsky performance scale, tumor histological grade, and adjuvant radiotherapy. RESULTS The Ki-67 proliferation index appeared to have a strong correlation with the grade of the tumor and the survival. Age, gender, adjuvant radiotherapy, surgical resection type (complete versus incomplete) did not have any influence on recurrence. The SMVD index correlated significantly with the 3 to 5-year survival. CONCLUSIONS Ki-67 and MVD indexes are important and useful markers in estimating the prognosis of oligodendrogliomas.
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Affiliation(s)
- Tugay Atalay
- Department of Neurosurgery, School of Medicine, Bozok University, Yozgat, Turkey E-mail :
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Yousaf J, Hills C, Dixit S, Achawal S, O'Brien D, Greenman J, Scott IS. Markers of cell division cycle in glioblastoma: significance in prediction of treatment response and patient prognosis. Br J Neurosurg 2013; 27:752-8. [PMID: 23477614 DOI: 10.3109/02688697.2013.773287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To investigate whether expression of regulatory components of the cell division cycle can be used independently to predict survival and response to adjuvant therapy in glioblastomas. METHOD A tissue micro-array, constructed using glioblastomas (n = 66), was stained using antibodies against minichromosome maintenance protein-2 (Mcm-2), expressed throughout the cell-division cycle; geminin, a protein that prevents re-initiation of DNA replication; and cyclin A, an S-phase cyclin. A semi-quantitative labelling index (LI) was calculated using an average of 18 high-power fields (hpf) in three replicate cores. The patients were divided into two groups: Group 1 (n = 50) underwent surgery and radiotherapy with 24 patients receiving temozolomide, and Group 2 (n = 16) received surgical treatment only. RESULTS The LIs (median +/- IQR) for Group 1 were as follows: Mcm-2, 36.7% (22.9%-51.8%); geminin, 7.8% (5.8%-10.5%); and cyclin A, 4.2% (2.4%-6.9%). Elevated LIs, higher than the median, for geminin and cyclin A correlated with prolonged survival when the tumours received adjuvant therapy (Kaplan-Meier curves, p = 0.0046 and p = 0.0063 for geminin and cyclin A, respectively). Linear regression analysis revealed positive correlations with survival for Mcm-2 (p = 0.0376), geminin (p = 0.0006) and cyclin A (p = 0.004). In Group 2, there was no relationship between the patient survival and the LI for any marker. CONCLUSIONS Geminin and cyclin A, each show potential as independent prognostic markers in glioblastomas receiving adjuvant therapy. This may reflect the fact that both geminin and cyclin A estimate proliferating tumour cell subpopulations sensitive to radio/chemotherapy. These markers could provide valuable prognostic information, even in small biopsies, especially if combined with O(6)MGMT expression and 1p;19q deletion status.
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Affiliation(s)
- J Yousaf
- Departments of Neurosurgery, Hull & East Yorkshire Hospitals NHS Trust , Hull Royal Infirmary, Hull , UK
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Geminin expression in small lung adenocarcinomas: Implication of prognostic significance. Lung Cancer 2011; 71:356-62. [DOI: 10.1016/j.lungcan.2010.06.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 05/24/2010] [Accepted: 06/22/2010] [Indexed: 11/15/2022]
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Molecular architecture of the DNA replication origin activation checkpoint. EMBO J 2010; 29:3381-94. [PMID: 20729811 DOI: 10.1038/emboj.2010.201] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 07/27/2010] [Indexed: 12/13/2022] Open
Abstract
Perturbation of DNA replication initiation arrests human cells in G1, pointing towards an origin activation checkpoint. We used RNAi against Cdc7 kinase to inhibit replication initiation and dissect this checkpoint in fibroblasts. We show that the checkpoint response is dependent on three axes coordinated through the transcription factor FoxO3a. In arrested cells, FoxO3a activates the ARF-∣Hdm2-∣p53 → p21 pathway and mediates p15(INK4B) upregulation; p53 in turn activates expression of the Wnt/β-catenin signalling antagonist Dkk3, leading to Myc and cyclin D1 downregulation. The resulting loss of CDK activity inactivates the Rb-E2F pathway and overrides the G1-S transcriptional programme. Fibroblasts concomitantly depleted of Cdc7/FoxO3a, Cdc7/p15, Cdc7/p53 or Cdc7/Dkk3 can bypass the arrest and proceed into an abortive S phase followed by apoptosis. The lack of redundancy between the checkpoint axes and reliance on several tumour suppressor proteins commonly inactivated in human tumours provides a mechanistic basis for the cancer-cell-specific killing observed with emerging Cdc7 inhibitors.
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Rodriguez-Acebes S, Proctor I, Loddo M, Wollenschlaeger A, Rashid M, Falzon M, Prevost AT, Sainsbury R, Stoeber K, Williams GH. Targeting DNA replication before it starts: Cdc7 as a therapeutic target in p53-mutant breast cancers. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:2034-45. [PMID: 20724597 DOI: 10.2353/ajpath.2010.100421] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Treatment options for triple-receptor negative (ER-/PR-/Her2-) and Her2-overexpressing (ER-/PR-/Her2+) breast cancers with acquired or de novo resistance are limited, and metastatic disease remains incurable. Targeting of growth signaling networks is often constrained by pathway redundancy or growth-independent cancer cell cycles. The cell-cycle protein Cdc7 regulates S phase by promoting DNA replication. This essential kinase acts as a convergence point for upstream growth signaling pathways and is therefore an attractive therapeutic target. We show that increased Cdc7 expression during mammary tumorigenesis is linked to Her2-overexpressing and triple-negative subtypes, accelerated cell cycle progression (P < 0.001), arrested tumor differentiation (P < 0.001), genomic instability (P = 0.019), increasing NPI score (P < 0.001), and reduced disease-free survival (HR = 1.98 [95% CI: 1.27-3.10]; P = 0.003), thus implicating its deregulation in the development of aggressive disease. Targeting Cdc7 with RNAi, we demonstrate that p53-mutant Her2-overexpressing and triple-negative breast cancer cell lines undergo an abortive S phase and apoptotic cell death due to loss of a p53-dependent Cdc7-inhibition checkpoint. In contrast, untransformed breast epithelial cells arrest in G1, remain viable, and are able to resume cell proliferation on recovery of Cdc7 kinase activity. Thus, Cdc7 appears to represent a potent and highly specific anticancer target in Her2-overexpressing and triple-negative breast cancers. Emerging Cdc7 kinase inhibitors may therefore significantly broaden the therapeutic armamentarium for treatment of the aggressive p53-mutant breast cancer subtypes identified in this study.
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Affiliation(s)
- Sara Rodriguez-Acebes
- Department of Pathology, Wolfson Institute for Biomedical Research, University College London, London, UK
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Yamazaki M, Fujii S, Murata Y, Hayashi R, Ochiai A. High expression level of geminin predicts a poor clinical outcome in salivary gland carcinomas. Histopathology 2010; 56:883-92. [DOI: 10.1111/j.1365-2559.2010.03561.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kayes OJ, Loddo M, Patel N, Patel P, Minhas S, Ambler G, Freeman A, Wollenschlaeger A, Ralph DJ, Stoeber K, Williams GH. DNA replication licensing factors and aneuploidy are linked to tumor cell cycle state and clinical outcome in penile carcinoma. Clin Cancer Res 2009; 15:7335-44. [PMID: 19920109 DOI: 10.1158/1078-0432.ccr-09-0882] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The DNA replication licensing machinery is integral to the control of proliferation, differentiation, and maintenance of genomic stability in human cells. We have analyzed replication licensing factors (RLF), together with DNA ploidy status, to investigate their role in progression of penile squamous cell carcinoma and to assess their utility as novel prognostic tools. EXPERIMENTAL DESIGN In a cohort of 141 patients, we linked protein expression profiles of the standard proliferation marker Ki67 and the RLFs Mcm2 and geminin to clinicopathologic variables, ploidy status, and clinical outcome. RESULTS Increased Ki67, Mcm2, and geminin levels were each significantly associated with arrested tumor differentiation (P < 0.0001) and aneuploidy (P < or = 0.01). Accelerated cell cycle progression was linked to increasing tumor size, stage, and depth of invasion. Aneuploid tumors significantly correlated with tumor grade (P < 0.0001). Biomarker expression and DNA ploidy status were significant predictors of locoregional disease progression [Mcm2 (P = 0.02), geminin (P = 0.02), Ki67 (P = 0.03), and aneuploidy (P = 0.03)] in univariate analysis. Importantly, aneuploidy was a strong independent prognosticator for overall survival (hazard ratio, 4.19; 95% confidence interval, 1.17-14.95; P = 0.03). Used in conjunction with conventional pathologic information, multiparameter analysis of these variables can stratify patients into low- or high-risk groups for disease progression (Harrell's c-index = 0.88). CONCLUSIONS Our findings suggest that RLFs and tumor aneuploidy may be used as an adjunct to conventional prognostic indicators, identifying men at high risk of disease progression. Our results also identify the DNA replication initiation pathway as a potentially attractive therapeutic target in penile squamous cell carcinoma.
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Affiliation(s)
- Oliver J Kayes
- Department of Pathology, University College London, London, United Kingdom
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Expression of Mcm2, geminin and Ki67 in normal oral mucosa, oral epithelial dysplasias and their corresponding squamous-cell carcinomas. Br J Cancer 2009; 100:1128-34. [PMID: 19293805 PMCID: PMC2669983 DOI: 10.1038/sj.bjc.6604967] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Proteins necessary for the normal regulation of the cell cycle include minichromosome maintenance protein 2 (Mcm2) and geminin. These are overexpressed in several premalignant and malignant tumours. The Mcm2/Ki67 ratio can be used to estimate the population of cells that are in early G1 (licensed to proliferate), and the geminin/Ki67 ratio can determine the relative length of G1. A high ratio indicates a short G1 and a high rate of cell proliferation. Mcm2 and geminin have been scarcely explored in oral epithelial dysplasia (OED) and oral squamous-cell carcinoma (OSCC). The purpose of this study was to identify the expression pattern of Mcm2, Ki67 and geminin in normal oral mucosa (NOM), OED and their subsequent OSCC, to determine if expression could help predict the prognosis of OED. Paraffin sections of 41 OED cases that progressed to carcinoma, 40 OED without malignant progression, 38 OSCC and 15 NOM were immunostained with antibodies against Mcm2, geminin and Ki67. Labelling indices (LIs) increased progressively from NOM, OED and OSCC (Mcm2, P<0.001; geminin, P<0.001 and Ki67, P<0.001). In all the OED cases (n=81) the levels of expression of Mcm2 (LI, 73.6), geminin (LI, 24.4) and Ki67 (LI, 44.5) were elevated indicating a constant cell-cycle re-entry. When the OED groups were compared, Mcm2 protein expression was higher in the OED with malignant progression (P=0.04), likewise there was a significant increase in the Mcm2/Ki67 and geminin/Ki67 ratios (P=0.04 and 0.02 respectively). Mcm2 and geminin proteins seem to be novel biomarkers of growth and may be useful prognostic tools for OED.
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Cell-cycle-phase progression analysis identifies unique phenotypes of major prognostic and predictive significance in breast cancer. Br J Cancer 2009; 100:959-70. [PMID: 19240714 PMCID: PMC2661794 DOI: 10.1038/sj.bjc.6604924] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Multiparameter analysis of core regulatory proteins involved in G1–S and G2–M cell-cycle transitions provides a powerful biomarker readout for assessment of the cell-cycle state. We have applied this algorithm to breast cancer to investigate how the cell cycle impacts on disease progression. Protein expression profiles of key constituents of the DNA replication licensing pathway (Mcm2, geminin) and mitotic machinery (Plk1, Aurora A and the Aurora substrate histone H3S10ph) were generated for a cohort of 182 patients and linked to clinicopathological parameters. Arrested differentiation and genomic instability were associated with an increased engagement of cells into the cell division cycle (P<0.0001). Three unique cell-cycle phenotypes were identified: (1) well-differentiated tumours composed predominantly of Mcm2-negative cells, indicative of an out-of-cycle state (18% of cases); (2) high Mcm2-expressing tumours but with low geminin, Aurora A, Plk1 and H3S10ph levels (S–G2–M progression markers), indicative of a G1-delayed/arrested state (24% cases); and (3) high Mcm2-expressing tumours and also expressing high levels of the S–G2–M progression markers, indicative of accelerated cell-cycle progression (58% of cases). The active cell-cycle progression phenotype had a higher risk of relapse when compared with out-of-cycle and G1-delayed/arrested phenotypes (HR=3.90 (1.81–8.40, P<0.001)), and was associated with Her-2 and triple negative subtypes (P<0.001). It is of note that high-grade tumours with the G1-delayed/arrested phenotype showed an identical low risk of relapse compared with well-differentiated out-of-cycle tumours (HR=1.00 (0.22–4.46), P=0.99). Our biomarker algorithm provides novel insights into the cell-cycle state of dynamic tumour cell populations in vivo. This information is of major prognostic significance and may impact on individualised therapeutic decisions. Patients with an accelerated phenotype are more likely to derive benefit from S- and M-phase-directed chemotherapeutic agents.
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Proliferation is the strongest prognosticator in node-negative breast cancer: significance, error sources, alternatives and comparison with molecular prognostic markers. Breast Cancer Res Treat 2008; 115:241-54. [DOI: 10.1007/s10549-008-0126-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2008] [Accepted: 07/03/2008] [Indexed: 01/19/2023]
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Identification of an arginine-rich motif in human papillomavirus type 1 E1;E4 protein necessary for E4-mediated inhibition of cellular DNA synthesis in vitro and in cells. J Virol 2008; 82:9056-64. [PMID: 18632869 DOI: 10.1128/jvi.01080-08] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Productive infections by human papillomaviruses (HPVs) are restricted to nondividing, differentiated keratinocytes. HPV early proteins E6 and E7 deregulate cell cycle progression and activate the host cell DNA replication machinery in these cells, changes essential for virus synthesis. Productive virus replication is accompanied by abundant expression of the HPV E4 protein. Expression of HPV1 E4 in cells is known to activate cell cycle checkpoints, inhibiting G(2)-to-M transition of the cell cycle and also suppressing entry of cells into S phase. We report here that the HPV1 E4 protein, in the presence of a soluble form of the replication-licensing factor (RLF) Cdc6, inhibits initiation of cellular DNA replication in a mammalian cell-free DNA replication system. Chromatin-binding studies show that E4 blocks replication initiation in vitro by preventing loading of the RLFs Mcm2 and Mcm7 onto chromatin. HPV1 E4-mediated replication inhibition in vitro and suppression of entry of HPV1 E4-expressing cells into S phase are both abrogated upon alanine replacement of arginine 45 in the full-length E4 protein (E1;E4), implying that these two HPV1 E4 functions are linked. We hypothesize that HPV1 E4 inhibits competing host cell DNA synthesis in replication-activated suprabasal keratinocytes by suppressing licensing of cellular replication origins, thus modifying the phenotype of the infected cell in favor of viral genome amplification.
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An investigation of the expression of G1-phase cell cycle proteins in focal cortical dysplasia type IIB. J Neuropathol Exp Neurol 2007; 66:1045-55. [PMID: 17984686 DOI: 10.1097/nen.0b013e3181598d23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Balloon cells (BCs) are the pathologic hallmark of focal cortical dysplasia type IIB, a common cause of pharmacoresistent epilepsy. Expression of markers of cell immaturity and of the proliferation marker minichromosome maintenance protein 2 (mcm2) have been previously shown in BCs, suggesting that these cells might represent a pool of less-differentiated cells licensed for replication. An alternative explanation is that these cells are the remnants of early cortical plate cells that have failed to differentiate or to be eliminated during development and are arrested in the cell cycle, a hypothesis that this study aims to explore. Using immunohistochemical methods and semiquantitative analysis in 19 cases of focal cortical dysplasia (ages 1-81 years), we studied the expression of cell cycle proteins important either in regulating progression through the G1 phase or inducing cell arrest and promoting premature senescence. Only a small fraction of BCs expressed geminin, suggesting that few BCs enter the S phase or complete the cell cycle. Variable expression of nonphosphorylated retinoblastoma protein (Rb), cdk4, and p53 was noted in BCs. Cyclin E, D1, cdk2, phosphorylated Rb (795 and 807/811), and checkpoint 2 expression levels were low in BCs. These findings suggest early rather than late G1 arrest. Cell senescence could be induced by an undefined cerebral insult during development or alternatively represent a physiologic replicative senescence. These findings also suggest that dysregulation of cell cycle pathways may occur in focal cortical dysplasia, which opens further areas for exploration as potential new treatment avenues.
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Williams GH, Stoeber K. Cell cycle markers in clinical oncology. Curr Opin Cell Biol 2007; 19:672-9. [PMID: 18032010 DOI: 10.1016/j.ceb.2007.10.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 10/05/2007] [Indexed: 01/07/2023]
Abstract
Analysis of complex and redundant pathways that control proliferation, differentiation, apoptosis and DNA damage response by global genome wide analysis is an intensive area of investigation aimed at identifying unique molecular signatures of prognostic significance in cancer. An alternative approach is to focus on the cell cycle machinery, which acts as an integration point for information transduced through upstream signalling pathways. Analysis of the DNA replication licensing pathway and the mitotic regulatory machinery in tumour biopsy material is now leading to the identification of novel biomarkers that are being exploited in cancer detection and prognostic assessment.
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Affiliation(s)
- Gareth H Williams
- Wolfson Institute for Biomedical Research, The Cruciform Building, University College London, Gower Street, London WC1E 6BT, UK
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Nogueira M, Kim HL. Molecular markers for predicting prognosis of renal cell carcinoma. Urol Oncol 2007; 26:113-24. [PMID: 18312928 DOI: 10.1016/j.urolonc.2007.03.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 03/08/2007] [Accepted: 03/15/2007] [Indexed: 01/10/2023]
Abstract
Metastatic or recurrent renal cell carcinoma (RCC) carries a poor prognosis and long term survival is rare. However, many small RCCs that are incidentally discovered have an indolent course even without treatment. The variability in clinical outcome is a reflection of the underlying tumor biology. Currently, clinical variables such as tumor stage and histologic grade are widely accepted surrogates for tumor-specific cellular and molecular processes. Ongoing advances in genomic and proteomic technologies have produced an expanding list of molecular markers for predicting prognosis. We review expression array studies evaluating molecular signatures for predicting prognosis in patients with RCC and describe specific prognostic markers that have been validated in at least 50 cases of RCC.
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Affiliation(s)
- Mark Nogueira
- Department of Urologic Oncology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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Kulkarni AA, Loddo M, Leo E, Rashid M, Eward KL, Fanshawe TR, Butcher J, Frost A, Ledermann JA, Williams GH, Stoeber K. DNA Replication Licensing Factors and Aurora Kinases are Linked to Aneuploidy and Clinical Outcome in Epithelial Ovarian Carcinoma. Clin Cancer Res 2007; 13:6153-61. [DOI: 10.1158/1078-0432.ccr-07-0671] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Barkley LR, Hong HK, Kingsbury SR, James M, Stoeber K, Williams GH. Cdc6 is a rate-limiting factor for proliferative capacity during HL60 cell differentiation. Exp Cell Res 2007; 313:3789-99. [PMID: 17689530 DOI: 10.1016/j.yexcr.2007.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 06/27/2007] [Accepted: 07/02/2007] [Indexed: 01/10/2023]
Abstract
The DNA replication (or origin) licensing pathway represents a critical step in cell proliferation control downstream of growth signalling pathways. Repression of origin licensing through down-regulation of the MCM licensing factors (Mcm2-7) is emerging as a ubiquitous route for lowering proliferative capacity as metazoan cells exit the cell division cycle into quiescent, terminally differentiated and senescent "out-of-cycle" states. Using the HL60 monocyte/macrophage differentiation model system and a cell-free DNA replication assay, we have undertaken direct biochemical investigations of the coupling of origin licensing to the differentiation process. Our data show that down-regulation of the MCM loading factor Cdc6 acts as a molecular switch that triggers loss of proliferative capacity during early engagement of the somatic differentiation programme. Consequently, addition of recombinant Cdc6 protein to in vitro replication reactions restores DNA replication competence in nuclei prepared from differentiating cells. Differentiating HL60 cells over-expressing either wild-type Cdc6 or a CDK phosphorylation-resistant Cdc6 mutant protein (Cdc6A4) exhibit an extended period of cell proliferation compared to mock-infected cells. Notably, differentiating HL60 cells over-expressing the Cdc6A4 mutant fail to down-regulate Cdc6 protein levels, suggesting that CDK phosphorylation of Cdc6 is linked to its down-regulation during differentiation and the concomitant decrease in cell proliferation. In this experimental model, Cdc6 therefore plays a key role in the sequential molecular events leading to repression of origin licensing and loss of proliferative capacity during execution of the differentiation programme.
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Affiliation(s)
- Laura R Barkley
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London, WC1E 6BT, UK
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Lau E, Tsuji T, Guo L, Lu SH, Jiang W. The role of pre‐replicative complex (pre‐RC) components in oncogenesis. FASEB J 2007; 21:3786-94. [PMID: 17690155 DOI: 10.1096/fj.07-8900rev] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Normal DNA replication is stringently regulated to ensure a timely occurrence no more than once per cell cycle. Abrogation of the exquisite control mechanisms that maintain this process results in detrimental gains and losses of genomic DNA commonly seen in cancer and developmental defects. Replication initiation proteins, known as prereplicative complex (pre-RC) proteins, serve as a primary level of regulation, controlling when DNA replication can begin. Unsurprisingly, several pre-RC proteins are overexpressed in cancer and serve as good tumor markers. However, their direct correlation with increasing tumor grade and poor prognosis has posed a long-standing question: Are pre-RC proteins oncogenic? Recently, a growing body of data indicates that deregulation of individual pre-RC proteins, either by overexpression or functional deficiency in several organismal models, results in significant and consistently perturbed cell cycle regulation, genomic instability, and, potentially, tumorigenesis. In this review, we examine this broad range of evidence suggesting that pre-RC proteins play roles during oncogenesis that are more than simply indicative of proliferation, supporting the notion that pre-RC proteins may potentially have significant diagnostic and therapeutic value.
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Affiliation(s)
- Eric Lau
- The Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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Shrestha P, Saito T, Hama S, Arifin MT, Kajiwara Y, Yamasaki F, Hidaka T, Sugiyama K, Kurisu K. Geminin: a good prognostic factor in high-grade astrocytic brain tumors. Cancer 2007; 109:949-56. [PMID: 17262828 DOI: 10.1002/cncr.22474] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Geminin is a nuclear protein that belongs to the DNA replication inhibitor group. It inhibits DNA replication by preventing Cdt1 from loading minichromosome maintenance protein onto chromatin, as is required for DNA replication. For this study, the authors investigated geminin expression in high-grade astrocytic tumors, including anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), with a view to predicting clinical outcomes on this basis in patients with these malignant brain tumors. METHODS Immunohistochemistry was used to detect geminin expression in 51 patients with high-grade astrocytic tumors (19 AA and 32 GBM). Samples were categorized by taking the median value as the cut-off point for constructing Kaplan-Meier curves. The relation of geminin expression to clinical outcome in these malignant brain tumors was analyzed by using the Kaplan-Meier method and a Cox proportional hazards regression model. RESULTS Geminin was expressed in all high-grade astrocytomas (mean geminin labeling index [LI], 24.90%). Kaplan-Meier curves showed that the group with higher geminin LI (>or=22.50%) had a better prognosis than the group with lower LI (<22.50%; P = .0296). Similarly, the Cox regression analysis showed that geminin expression has a significant correlation with survival in patients with high-grade astrocytoma (P = .0278), especially in an early stage. CONCLUSIONS Although it is an inhibitor of DNA proliferation and, thus, is a cell cycle inhibitor, geminin expression was found in all malignant astrocytic tumors. The geminin LI was a significant predictive factor of outcomes in patients with high-grade astrocytoma, with higher expression indicating a good prognosis.
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Affiliation(s)
- Prabin Shrestha
- Department of Neurosurgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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Dudderidge TJ, McCracken SR, Loddo M, Fanshawe TR, Kelly JD, Neal DE, Leung HY, Williams GH, Stoeber K. Mitogenic growth signalling, DNA replication licensing, and survival are linked in prostate cancer. Br J Cancer 2007; 96:1384-93. [PMID: 17406359 PMCID: PMC2360172 DOI: 10.1038/sj.bjc.6603718] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Activation of mitogen/extracellular-signal-regulated kinase kinase 5/extracellular signal-regulated kinase-5 (MEK5/ERK5) growth signalling is coupled to increased cell proliferation in prostate cancer (PCa). Dysregulation of the DNA replication licensing pathway, a critical step in growth control downstream of transduction signalling pathways, is associated with development of PCa. In this study we have investigated linkages between the MEK5/ERK5 pathway and DNA replication licensing during prostate carcinogenesis. The effects of increased MEK5/ERK5 signalling on the expression of replication licensing factors Mcm2 and geminin and the proliferation marker Ki67 were studied in an ecdysone-inducible system expressing a constitutively activated mutant of MEK5 in EcR293 cells and in stable ERK5 over-expressing PC3 clones. In parallel, expression of these biomarkers in PCa biopsy specimens (n=58) was studied and compared to clinicopathological parameters. In both in vitro systems induction of MEK5 expression resulted in increased levels of phosphorylated ERK5 and Mcm2, geminin and Ki67 proteins. In PCa specimens average Mcm2 expression was greater than Ki67 and geminin expression (median labelling index (LI) 36.7, 18.1, and 3.4% respectively), consistent with their differential expression according to growth status (P<0.0001). Mcm2, geminin and Ki67 expression were significantly associated with Gleason grade (P=0.0002, P=0.0003, P=0.004); however there was no link with T or M stage. There was a significant relationship between increasing ERK5 expression and increasing Mcm2 (P=0.003) and Ki67 (P=0.009) expression, with non-significant trends seen with increasing MEK5 expression. There were significant associations between Gleason grade and the number of cells traversing G1 phase (Ki67LI-gemininLI; (P=0.001)), with high ERK5 levels associated with both an increase in replication licensed but non-cycling cells (Mcm2LI-Ki67LI; (P=0.01)) and accelerated cell cycle progression (gemininLI/Ki67LI; (P= 0.005)), all indicative of a shift towards increasing proliferative potential. While Mcm2 and Ki67 were both prognostic factors on univariate analysis, only Mcm2 remained an independent prognostic marker on multivariate analysis. Taken together, our data show that induction of MEK5/ERK5 signalling is linked to activation of the DNA replication licensing pathway in PCa, and that the strong prognostic value of MCM proteins may result from their function as relay stations coupling growth regulatory pathways to genome duplication.
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Affiliation(s)
- T J Dudderidge
- Department of Pathology and Royal Free and University College Medical School, University College London, Rockefeller Building, University Street, London, WC1E 6JJ, UK
| | - S R McCracken
- Northern Institute for Cancer Research, University of Newcastle, Paul O'Gorman Building, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - M Loddo
- Department of Pathology and Royal Free and University College Medical School, University College London, Rockefeller Building, University Street, London, WC1E 6JJ, UK
| | - T R Fanshawe
- Department of Public Health and Primary Care, Centre for Applied Medical Statistics, Institute of Public Health,University of Cambridge, Forvie Site, Robinson Way, Cambridge, CB2 2SR, UK
| | - J D Kelly
- Department of Oncology and Hutchison MRC Research Centre, University of Cambridge, Hills Road, Cambridge, CB2 2XZ, UK
| | - D E Neal
- Department of Oncology and Hutchison MRC Research Centre, University of Cambridge, Hills Road, Cambridge, CB2 2XZ, UK
| | - H Y Leung
- Northern Institute for Cancer Research, University of Newcastle, Paul O'Gorman Building, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - G H Williams
- Department of Pathology and Royal Free and University College Medical School, University College London, Rockefeller Building, University Street, London, WC1E 6JJ, UK
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London, WC1E 6BT, UK
- E-mail:
| | - K Stoeber
- Department of Pathology and Royal Free and University College Medical School, University College London, Rockefeller Building, University Street, London, WC1E 6JJ, UK
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London, WC1E 6BT, UK
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Wharton SB, Maltby E, Jellinek DA, Levy D, Atkey N, Hibberd S, Crimmins D, Stoeber K, Williams GH. Subtypes of oligodendroglioma defined by 1p,19q deletions, differ in the proportion of apoptotic cells but not in replication-licensed non-proliferating cells. Acta Neuropathol 2007; 113:119-27. [PMID: 17160531 PMCID: PMC1781098 DOI: 10.1007/s00401-006-0177-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 11/16/2006] [Accepted: 11/20/2006] [Indexed: 01/08/2023]
Abstract
Oligodendrogliomas may be divided into those with deletion of chromosomes 1p and 19q (Del+), and those without (Del−). Del+ tumours show better survival and chemoresponsiveness but the reason for this difference is unknown. We have investigated whether these subgroups differ in (a) apoptotic index, (b) the proportion of cells licensed for DNA replication but not in-cycle, and (c) the relative length of G1-phase. Fluorescence in situ hybridisation with probes to 1p and 19q was used to determine the deletion status of 54 oligodendrogliomas, including WHO grades II and III. The apoptotic index was determined using counts of apoptotic bodies. Replication-licensed non-proliferating cells were determined from the Mcm2 minus Ki67 labelling index, whilst the geminin to Ki67 ratio was used as a measure of the relative length of G1. Del+ oligodendrogliomas showed a higher apoptotic index than Del− tumours (P = 0.037); this was not accounted for by differences in tumour grade or in proliferation. There were no differences in the Mcm2 − Ki67 index or in the geminin/Ki67 ratio between the subgroups, but grade III tumours showed a higher proportion of licensed non-proliferating cells than grade II tumours (P = 0.001). An increased susceptibility to apoptosis in oligodendrogliomas with 1p ± 19q deletion may be important in their improved clinical outcome compared to Del− tumours.
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Affiliation(s)
- S B Wharton
- Department of Histopathology, Sheffield Teaching Hospitals, and Academic Unit of Pathology, University of Sheffield, Medical School, UK.
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Quaglia A, McStay M, Stoeber K, Loddo M, Caplin M, Fanshawe T, Williams G, Dhillon A. Novel markers of cell kinetics to evaluate progression from cirrhosis to hepatocellular carcinoma. Liver Int 2006; 26:424-32. [PMID: 16629645 DOI: 10.1111/j.1478-3231.2006.01242.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND We investigated cell cycle kinetics of nodular lesions in cirrhosis to differentiate hepatocellular carcinoma (HCC) from its precursor lesions. METHODS Twelve small HCC, 10 regenerative (RN), six large regenerative (LRN), and five dysplastic nodules (DN), identified in explant cirrhotic livers of five consecutive patients transplanted at Royal Free Hospital in 2002. Immunoperoxidase for MCM2, geminin and Ki67 was performed and the percentage of positive cells counted. RESULTS The proportion of cells expressing MCM2 was more than those expressing Ki67, which in turn was more than those expressing geminin (overall median=16%, 2% and 0.5%, respectively, P<0.001). There was a statistically significant trend of increasing Ki67 expression (P=0.006), from RN to HCC; this trend was not statistically significant for geminin (P=0.18) or MCM2 (P=0.51). The median percentage of cells expressing Ki67 was 1% in RN, 0.5% in LRN, 2.2% in DN and 5.4% in HCC. The combination of these markers identified four different cell kinetics patterns: 'resting' (G0 cells: MCM2 -ve, Ki67 -ve, geminin -ve); 'licensed' (MCM2 +ve, Ki67 -ve, geminin -ve); 'slowly growing' (G1 phase arrest, MCM2 +ve, Ki67 +ve, low (0.4%) geminin) and expanding (MCM2 +ve, Ki67 +ve, geminin +ve) nodules. CONCLUSIONS The combination of MCM2, geminin and Ki67 could represent a valuable tool in the understanding of HCC progression in cirrhosis.
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Affiliation(s)
- Alberto Quaglia
- Department of Histopathology, Royal Free and University College Medical School, London, UK.
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Montanari M, Macaluso M, Cittadini A, Giordano A. Role of geminin: from normal control of DNA replication to cancer formation and progression? Cell Death Differ 2006; 13:1052-6. [PMID: 16628231 DOI: 10.1038/sj.cdd.4401932] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Seo J, Chung YS, Sharma GG, Moon E, Burack WR, Pandita TK, Choi K. Cdt1 transgenic mice develop lymphoblastic lymphoma in the absence of p53. Oncogene 2006; 24:8176-86. [PMID: 16261166 DOI: 10.1038/sj.onc.1208881] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The exact duplication of chromosomal DNA during each cell cycle ensures the correct inheritance of genetic material from mother to daughter cells. In eukaryotic cells, DNA replication can occur only when the origin of DNA replication is accurately marked by a group of proteins termed licensing proteins. One such protein is Cdt1, which is recruited first to the origin of DNA replication followed by cell division cycle 6 (Cdc6) and mini-chromosome maintenance proteins (Mcms). We previously reported that NIH3T3 cells overexpressing Cdt1 readily formed tumors in mice. To further investigate its oncogenic mechanism, we generated transgenic mice expressing Cdt1 in thymocytes. Our studies demonstrated that T-cell-directed Cdt1 transgenic mice showed normal T-cell development. However, such transgenic mice developed thymic lymphoblastic lymphoma when crossed with p53 null mice. Furthermore, tumor cells derived from NIH3T3 cells overexpressing Cdt1 displayed numerical and structural chromosomal aberrations in the form of ploidy, double minutes, translocation, inversion, chromosome end-to-end fusion and robertsonian mutation. Collectively, our studies suggest that Cdt1 overexpression most likely contributes to tumorigenecity by causing genomic instability.
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Affiliation(s)
- Junghee Seo
- Department of Pathology and Immunology, Washington University School of Medicine, Suwon, Korea
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Honeycutt KA, Chen Z, Koster MI, Miers M, Nuchtern J, Hicks J, Roop DR, Shohet JM. Deregulated minichromosomal maintenance protein MCM7 contributes to oncogene driven tumorigenesis. Oncogene 2006; 25:4027-32. [PMID: 16518415 DOI: 10.1038/sj.onc.1209435] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Minichromosomal maintenance protein 7 (MCM7) is an essential component of the replication helicase complex (MCM2-7) required for DNA replication. Although this function is highly conserved among eukaryotes, additional functions for the MCM molecules continue to be described. Minichromosomal maintenance protein 7 is a marker for proliferation and is upregulated in a variety of tumors including neuroblastoma, prostate, cervical and hypopharyngeal carcinomas. To further investigate the general role of MCM7 in tumorigenesis, we generated a mouse model with deregulated MCM7 expression targeted to the basal layer of the epidermis using the keratin 14 (K14) promoter (K14.MCM7). When subjected to a two-stage chemical carcinogenesis protocol (dimethylbenz[alpha]anthracene (DMBA) initiation with 12-ortho-tetradecanoylphorbol-13-acetate promotion), K14.MCM7 mice showed significantly increased incidence and prevalence of tumor development relative to controls. Furthermore, within 40 weeks of treatment over 45% K14.MCM7 mice exhibited tumors that had converted to squamous cell carcinomas versus none in the control group. As predicted from previous skin carcinogenesis studies using DMBA as the initiating agent, Ras mutations where found in more than 90% of tumors isolated from K14.MCM7 mice. Whereas previous studies have shown that MCM7 is useful as a proliferation marker, our data suggest that deregulated MCM7 expression actively contributes to tumor formation, progression and malignant conversion.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/pharmacology
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Animals
- Biomarkers, Tumor/biosynthesis
- Biomarkers, Tumor/genetics
- Carcinogens/pharmacology
- Carcinogens/toxicity
- Carcinoma, Squamous Cell/chemically induced
- Carcinoma, Squamous Cell/genetics
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Cell Cycle Proteins/biosynthesis
- Cell Cycle Proteins/genetics
- Cell Proliferation
- Cell Transformation, Neoplastic/chemically induced
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- Gene Expression Regulation, Neoplastic/genetics
- Genes, ras/genetics
- Humans
- Mice
- Mice, Transgenic
- Minichromosome Maintenance Complex Component 7
- Mutation
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Neoplasms, Experimental/chemically induced
- Neoplasms, Experimental/genetics
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Nuclear Proteins/biosynthesis
- Nuclear Proteins/genetics
- Skin Neoplasms/chemically induced
- Skin Neoplasms/genetics
- Skin Neoplasms/metabolism
- Skin Neoplasms/pathology
- Tetradecanoylphorbol Acetate/analogs & derivatives
- Tetradecanoylphorbol Acetate/pharmacology
- Tetradecanoylphorbol Acetate/toxicity
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Affiliation(s)
- K A Honeycutt
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Shetty A, Loddo M, Fanshawe T, Prevost AT, Sainsbury R, Williams GH, Stoeber K. DNA replication licensing and cell cycle kinetics of normal and neoplastic breast. Br J Cancer 2006; 93:1295-300. [PMID: 16278669 PMCID: PMC2361513 DOI: 10.1038/sj.bjc.6602829] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mcm2–7 (MCM) proteins are part of the origin licensing machinery that regulates initiation of DNA replication. Geminin is a licensing repressor and prevents reinitiation of DNA replication during S–G2–M phase by blocking reloading of Mcm2–7 at replication origins. Here, we have analysed these replication licensing factors (RLFs) to determine whether the pathway becomes deregulated during mammary carcinogenesis, and have assessed their potential value as prognostic markers. Protein expression profiles were generated for Ki67, Mcm2, geminin, HER-2, ER and PR in a series of reduction mammoplasty (n=18) and breast cancer specimens (n=120), and compared to clinicopathological parameters. A large proportion of epithelial cells of the terminal duct lobular unit reside in a primed ‘replication licensed’ but not proliferating state. This state is characterised by Mcm2 expression and absence of Ki67 and the S/G2/M marker geminin. In breast cancers, increasing tumour grade is associated with increased Ki67, Mcm2 and geminin expression. The Mcm2/Ki67 ratio decreases through the grades, indicating a shift from a predominantly licensed state to an actively proliferating state. This shift is associated with an increase in the geminin/Ki67 ratio, signifying a shortening of G1 phase in breast cancer cells. Ki67, Mcm2 and the Mcm2/Ki67 ratio are statistically significantly associated with the Nottingham Prognostic Index (NPI), but geminin and the geminin/Ki67 ratio are not. Ki67, Mcm2 and Mcm2/Ki67 are highly correlated with one another, with Mcm2 being the single most important predictor of NPI score (P<0.001). However, only 12% of variation in NPI is explained by Mcm2, as the labelling index for this marker is approaching 100% for many of the high-grade tumours. The origin licensing phenotypes of normal breast and breast cancers therefore relate to their cellular differentiation status, and high-level MCM expression in more poorly differentiated tumours severely constrains their use as prognostic markers in breast cancer.
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Affiliation(s)
- A Shetty
- Department of Pathology, University College London, Rockefeller Building, University Street, London WC1E 6JJ, UK
| | - M Loddo
- Department of Pathology, University College London, Rockefeller Building, University Street, London WC1E 6JJ, UK
| | - T Fanshawe
- Centre for Applied Medical Statistics, Department of Public Health and Primary Care, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 2SR, UK
| | - A T Prevost
- Centre for Applied Medical Statistics, Department of Public Health and Primary Care, University of Cambridge, Forvie Site, Robinson Way, Cambridge CB2 2SR, UK
| | - R Sainsbury
- Department of Surgery, Royal Free and University College Medical School, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK
- Department of Surgery, Royal Free and University College Medical School, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ, UK. E-mail:
| | - G H Williams
- Department of Pathology, University College London, Rockefeller Building, University Street, London WC1E 6JJ, UK
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London WC1E 6BT, UK
| | - K Stoeber
- Department of Pathology, University College London, Rockefeller Building, University Street, London WC1E 6JJ, UK
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London WC1E 6BT, UK
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Schrader C, Janssen D, Klapper W, Siebmann JU, Meusers P, Brittinger G, Kneba M, Tiemann M, Parwaresch R. Minichromosome maintenance protein 6, a proliferation marker superior to Ki-67 and independent predictor of survival in patients with mantle cell lymphoma. Br J Cancer 2005; 93:939-45. [PMID: 16189522 PMCID: PMC2361659 DOI: 10.1038/sj.bjc.6602795] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Minichromosome maintenance protein 6 (MCM6) is one of six proteins of the MCM family which are involved in the initiation of DNA replication and thus represent a marker of proliferating cells. Since the level of cell proliferation is the most valuable predictor of survival in mantle cell lymphoma (MCL), we investigated lymph node biopsy specimens from 70 patients immunohistochemically with a monoclonal antibody against MCM6. The percentage of MCM6 expressing lymphoma cells ranged from 12.0 to 95.6%, with a mean of 61.0%, and was significantly higher than the percentage of Ki-67-positive cells (P<0.0001). Surprisingly, the ratio of MCM6-positive cells to Ki-67-positive cells was higher than in normal stimulated peripheral blood mononuclear cells, indicating a cell early G1-phase arrest in MCL. A high MCM6 expression level of more than 75% positive cells was associated with a significantly shorter overall survival time (16 months) compared to MCL with a low MCM6 expression level of less than 25% (no median reached, P<0.0001). Multivariate analysis revealed MCM6 to be an independent predictor of survival that is superior to the international prognostic factor and the Ki-67 index. Therefore, aside from gene expression profiling, immunohistochemical detection of MCM6 seems to be the most promising marker for predicting the outcome in MCL.
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Affiliation(s)
- C Schrader
- Second Department of Internal Medicine and Hematology, University Hospital of Schleswig-Holstein, Campus Kiel, Chemnitzstr. 33, 24116 Kiel, Germany.
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Dudderidge TJ, Stoeber K, Loddo M, Atkinson G, Fanshawe T, Griffiths DF, Williams GH. Mcm2, Geminin, and KI67 define proliferative state and are prognostic markers in renal cell carcinoma. Clin Cancer Res 2005; 11:2510-7. [PMID: 15814627 DOI: 10.1158/1078-0432.ccr-04-1776] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE The origin licensing factors minichromosome maintenance 2 (Mcm2) and Geminin have recently been identified as critical regulators of growth and differentiation. Here we have investigated the regulation of these licensing factors together with Ki67 to further elucidate the cell cycle kinetics of renal cell carcinoma (RCC). Furthermore, we have examined the role of Ki67, Mcm2, and Geminin in disease-free survival after nephrectomy in patients with localized RCC. EXPERIMENTAL DESIGN Tissue sections from 176 radical nephrectomy specimens were immunohistochemically stained with Mcm2, Geminin, and Ki67 antibodies. Labeling indices (LI) for these markers were compared with clinicopathologic parameters (median follow-up 44 months). RESULTS In RCC, Mcm2 is expressed at much higher levels than Ki-67 and Geminin, respectively [medians 41.6%, 7.3%, and 3.5% (P < 0.001)] and was most closely linked to tumor grade (P < 0.001). For each marker, Kaplan-Meier survival curves provided strong evidence that increased expression is associated with reduced disease-free survival time (P < 0.001). Additionally, an Mcm2-Ki67 LI identified a unique licensed but nonproliferating population of tumor cells that increased significantly with tumor grade (P = 0.004) and was also of prognostic value (P = 0.01). On multivariate analysis, grade, vascular invasion, capsular invasion, Ki67 LI >12%, and age were found to be independent prognostic markers. CONCLUSIONS Although Ki67 is identified as an independent prognostic marker, semiquantitative assessment is difficult due to the very low proliferative fraction identified by this marker. In contrast, Mcm2 identifies an increased growth fraction that is closely linked to grade, provides prognostic information, and is amenable to semiquantitative analysis in routine pathologic assessment.
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Affiliation(s)
- Tim J Dudderidge
- Wolfson Institute for Biomedical Research, Department of Histopathology, London, United Kingdom
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40
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Ji C, Li L, Gebre M, Pasdar M, Li L. Identification and Quantification of Differentially Expressed Proteins in E-Cadherin Deficient SCC9 Cells and SCC9 Transfectants Expressing E-Cadherin by Dimethyl Isotope Labeling, LC−MALDI MS and MS/MS. J Proteome Res 2005; 4:1419-26. [PMID: 16083295 DOI: 10.1021/pr050094h] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A strategy based on isotope labeling of peptides and liquid chromatography matrix-assisted laser desorption ionization mass spectrometry (LC-MALDI MS) has been employed to accurately quantify and confidently identify differentially expressed proteins between an E-cadherin-deficient human carcinoma cell line (SCC9) and its transfectants expressing E-cadherin (SCC9-E). Proteins extracted from each cell line were tryptically digested and the resultant peptides were labeled individually with either d(0)- or d(2)-formaldehyde. The labeled peptides were combined and the peptide mixture was separated and fractionated by a strong cation exchange (SCX) column. Peptides from each SCX fraction were further separated by a microbore reversed-phase (RP) LC column. The effluents were then directly spotted onto a MALDI target using a heated droplet LC-MALDI interface. After mixing with a MALDI matrix, individual sample spots were analyzed by MALDI quadrupole time-of-flight MS, using an initial MS scan to quantify the dimethyl labeled peptide pairs. MS/MS analysis was then carried out on the peptide pairs having relative peak intensity changes of greater than 2-fold. The MS/MS spectra were subjected to database searching for protein identification. The search results were further confirmed by comparing the MS/MS spectra of the peptide pairs. Using this strategy, we detected and compared relative peak intensity changes of 5480 peptide pairs. Among them, 320 peptide pairs showed changes of greater than 2-fold. MS/MS analysis of these changing pairs led to the identification of 49 differentially expressed proteins between the parental SCC9 cells and SCC9-E transfectants. These proteins were determined to be involved in different pathways regulating cytoskeletal organization, cell adhesion, epithelial polarity, and cell proliferation. The changes in protein expression were consistent with increased cell-cell and cell-matrix adhesion and decreased proliferation in SCC9-E cells, in line with E-cadherin tumor suppressor activity. Finally, the accuracy of the MS quantification and subcellular localization for 6 differentially expressed proteins were validated by immunoblotting and immunofluorescence assays.
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Affiliation(s)
- Chengjie Ji
- Departments of Chemistry and Cell Biology, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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Wharton SB, Williams GH, Stoeber K, Gelsthorpe CH, Baxter L, Johnson AL, Ince PG. Expression of Ki67, PCNA and the chromosome replication licensing protein Mcm2 in glial cells of the ageing human hippocampus increases with the burden of Alzheimer-type pathology. Neurosci Lett 2005; 383:33-8. [PMID: 15936508 DOI: 10.1016/j.neulet.2005.04.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 03/29/2005] [Accepted: 04/01/2005] [Indexed: 10/25/2022]
Abstract
Cell-cycle mechanisms may be aberrantly reactivated in the ageing brain and associated with the development of pathology, including Alzheimer's disease. Activation of cell-cycle mechanisms in glia has, however, been little studied. Our aim was to determine whether expression of a marker for chromosomal replication licensing, Mcm2, occurs in glia of the ageing hippocampus, and to compare its expression to that of Ki67 and PCNA. Blocks of hippocampus were obtained from 19 elderly brains derived from the MRC-CFAS neuropathology cohort, which included a spectrum of Alzheimer-type pathology, semi-quantified using the Braak scoring system for neurofibrillary tangles. Mcm2, PCNA and Ki67 were detected immunohistochemically. Expression of Mcm2, Ki67 and PCNA was observed in glial cells and neurons, with a trend to increased expression in association with higher burdens of Alzheimer-type pathology. Mcm2 expression in glial cells showed a significant linear trend across Braak stages (P = 0.043). This study demonstrates that grey and white matter glial cells show expression of cell-cycle markers in the ageing brain and that re-licensing for chromosomal replication is a component of the mechanisms activated. A quantitative relationship to the burden of Alzheimer-type pathology suggests that cell-cycle re-entry in glial cells may be important in the pathogenesis of age-related neurodegeneration.
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Affiliation(s)
- Stephen B Wharton
- Academic Unit of Pathology, University of Sheffield, Medical School, UK.
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Thom M, Martinian L, Williams G, Stoeber K, Sisodiya SM. Cell proliferation and granule cell dispersion in human hippocampal sclerosis. J Neuropathol Exp Neurol 2005; 64:194-201. [PMID: 15804050 DOI: 10.1093/jnen/64.3.194] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Granule cell dispersion (GCD) is observed in approximately 40% of cases of hippocampal sclerosis (HS) in patients with epilepsy. Studies in animal models suggest that GCD may be a consequence of enhanced proliferation of granule cell precursors as a result of seizures. We quantified the number of cells in cycle in subfields of the hippocampus with immunohistochemistry for Mcm2 in 14 HS cases with or without severe GCD compared to 6 epilepsy patients without classical HS or GCD as well as 5 postmortem controls. Higher numbers of Mcm2-positive cells were seen in the region of the granule cell layer in patients with severe GCD, and immunolabeling with Geminin and Ki-67 confirmed a proportion were progressing through cycle. Double labeling with Mcm2 and GFAP confirmed the majority of these cycling cells were GFAP-negative and occasional cells stained colocalized with stem cell marker nestin. These findings support the view that GCD may be a phenomenon related to increased progenitor cell proliferation in patients with hippocampal damage and chronic epilepsy.
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Affiliation(s)
- Maria Thom
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, London, UK.
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Obermann EC, Eward KL, Dogan A, Paul EA, Loddo M, Munson P, Williams GH, Stoeber K. DNA replication licensing in peripheral B-cell lymphoma. J Pathol 2005; 205:318-28. [PMID: 15682442 DOI: 10.1002/path.1695] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Peripheral B-cell lymphomas representing 90% of lymphoid neoplasms are divided into low- and high-growth fraction lymphomas. Here we investigate regulation of DNA replication licensing during B-cell lymphomagenesis. Combined analysis of origin licensing factors Mcm2 and geminin with the proliferation marker Ki67 in SLL/CLL, MCL, DLBCL and Burkitt lymphoma reveals for the first time the precise cell cycle state of these entities. Given that tight Mcm2 downregulation defines the quiescent state (G0) and that both high- and low-growth fraction lymphomas express Mcm2, the data demonstrate that neoplastic lymphocytes of SLL/CLL and MCL reside in an "in-cycle" G1 state and not in G0 as previously thought. Absence of the S/G2/M phase marker geminin in SLL/CLL and MCL further indicates failure of cell cycle progression in these tumours. In contrast, the high-growth fraction lymphomas DLBCL and Burkitt lymphoma exhibit differential expression of geminin, with the geminin/Ki67 ratio increasing for more aggressive neoplasms in keeping with a shortened G1 phase and thus representing an important discriminator for differential diagnosis. These data provide new insights into abrogation of cell cycle control during B cell lymphomagenesis and suggest that combined analysis of origin licensing factors may contribute to improved treatment decisions and prognosis in haematopoietic malignancies.
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MESH Headings
- Biomarkers, Tumor/metabolism
- Cell Cycle
- Cell Cycle Proteins/metabolism
- Cell Transformation, Neoplastic/pathology
- DNA Replication
- DNA, Neoplasm/genetics
- Diagnosis, Differential
- Flow Cytometry/methods
- Geminin
- Humans
- Ki-67 Antigen/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Lymphoma, B-Cell/diagnosis
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/metabolism
- Lymphoma, B-Cell/pathology
- Minichromosome Maintenance Complex Component 2
- Mitosis
- Neoplasm Proteins/metabolism
- Nuclear Proteins/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- Ellen C Obermann
- Department of Histopathology, University College London, Rockefeller Building, University Street, London, WC1E 6JJ, United Kingdom
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Eward KL, Obermann EC, Shreeram S, Loddo M, Fanshawe T, Williams C, Jung HI, Prevost AT, Blow JJ, Stoeber K, Williams GH. DNA replication licensing in somatic and germ cells. J Cell Sci 2004; 117:5875-86. [PMID: 15522891 DOI: 10.1242/jcs.01503] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The DNA replication (or origin) licensing system ensures precise duplication of the genome in each cell cycle and is a powerful regulator of cell proliferation in metazoa. Studies in yeast, Drosophila melanogaster and Xenopus laevis have characterised the molecular machinery that constitutes the licensing system, but it remains to be determined how this important evolutionary conserved pathway is regulated in Homo sapiens. We have investigated regulation of the origin licensing factors Cdc6, Cdt1, Mcm2 and Geminin in human somatic and germ cells. Cdc6 and Cdt1 play an essential role in DNA replication initiation by loading the Mcm2-7 complex, which is required for unwinding the DNA helix, onto chromosomal origins. Geminin is a repressor of origin licensing that blocks Mcm2-7 loading onto origins. Our studies demonstrate that Cdc6, Cdt1 and Mcm2 play a central role in coordinating growth during the proliferation-differentiation switch in somatic self-renewing systems and that Cdc6 expression is rate-limiting for acquisition of replication competence in primary oocytes. In striking contrast, we show that proliferation control during male gametogenesis is not linked to Cdc6 or Mcm2, but appears to be coordinated by the negative regulator Geminin with Cdt1 becoming rate-limiting in late prophase. Our data demonstrate a striking sexual dimorphism in the mechanisms repressing origin licensing and preventing untimely DNA synthesis during meiosis I, implicating a pivotal role for Geminin in maintaining integrity of the male germline genome.
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Affiliation(s)
- Kathryn Leigh Eward
- Wolfson Institute for Biomedical Research, University College London, The Cruciform Building, Gower Street, London, WC1E 6BT, UK
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