1
|
Wu K, Huang S, Zhao Y, Umar A, Chen H, Yu Z, Huang J. Hepatocyte nuclear factor 4 located in different developmental stages in Schistosoma japonicum and involved in important metabolic pathways. Biomed J 2024:100726. [PMID: 38621646 DOI: 10.1016/j.bj.2024.100726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 04/01/2024] [Accepted: 04/08/2024] [Indexed: 04/17/2024] Open
Abstract
BACKGROUND Nuclear receptors (NRs) are vital for regulating gene expression un organisms. Hepatocyte nuclear factor 4 (HNF4), a class of NRs, participates in blood feeding and intestinal maintenance in schistosomes. However, there is limited research on the molecular and functional characterization of HNF4 in Schistosoma japonicum (S. japonicum). METHODS Highly specific polyclonal antibodies were generated to analyze the expression and tissue localization of S. japonicum HNF4 (SjHNF4). The potential biological functions of SjHNF4 were characterized by transcriptome and pull-down analysis. Subsequently, enrichment analysis was performed to identify the specific signaling pathways linked to SjHNF4. RESULTS The SjHNF4 protein was expressed heterologously and purified successfully. High purity and high potency polyclonal antibodies were further prepared. The expression of SjHNF4 was higher in female compared to male worms at both transcriptional and protein levels. Female worms expressed SjHNF4 in their perithecium, reproductive system, and certain parts of the intestinal tissues. SjHNF4 was also detected in the perithecium of male worms, as well as in the head, body of cercaria, and eggs. Furthermore, our findings highlighted the potential role of SjHNF4 in blood feeding and its interaction with crucial pathways such as glucose metabolism, lipid metabolism, and nucleotide metabolism. CONCLUSIONS This study shed light on the location of SjHNF4 in different life stages of S. japonicum, particularly associated with the female schistosomes. A strong correlation was observed between SjHNF4 and essential metabolic pathways. These findings laid a solid groundwork for the research on the relationship between NRs and schistosomes.
Collapse
Affiliation(s)
- Kaijuan Wu
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013
| | - Shuaiqin Huang
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013
| | - Yiming Zhao
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013
| | - Abdulrahim Umar
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013
| | - Hao Chen
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013
| | - Zheng Yu
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013
| | - Jing Huang
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, Hunan, China. 410013; China-Africa Research Center of Infectious Diseases, Central South University, Changsha Hunan, China. 410013.
| |
Collapse
|
2
|
Hong A, Umar A, Chen H, Yu Z, Huang J. Advances in the study of the interaction between schistosome infections and the host's intestinal microorganisms. Parasit Vectors 2024; 17:185. [PMID: 38600604 PMCID: PMC11007984 DOI: 10.1186/s13071-024-06245-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 03/12/2024] [Indexed: 04/12/2024] Open
Abstract
Schistosomiasis, also called bilharziasis, is a neglected tropical disease induced by schistosomes that infects hundreds of millions of people worldwide. In the life cycle of schistosomiasis, eggs are regarded as the main pathogenic factor, causing granuloma formation in the tissues and organs of hosts, which can cause severe gastrointestinal and liver granulomatous immune responses and irreversible fibrosis. Increasing evidence suggests that the gut microbiome influences the progression of schistosomiasis and plays a central role in liver disease via the gut-liver axis. When used as pharmaceutical supplements or adjunctive therapy, probiotics have shown promising results in preventing, mitigating, and even treating schistosomiasis. This review elucidates the potential mechanisms of this three-way parasite-host-microbiome interaction by summarizing schistosome-mediated intestinal flora disorders, local immune changes, and host metabolic changes, and elaborates the important role of the gut microbiome in liver disease after schistosome infection through the gut-liver axis. Understanding the mechanisms behind this interaction may aid in the discovery of probiotics as novel therapeutic targets and sustainable control strategies for schistosomiasis.
Collapse
Affiliation(s)
- Ao Hong
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, China
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Abdulrahim Umar
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Hao Chen
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, China
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Zheng Yu
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Jing Huang
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, China.
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China.
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China.
| |
Collapse
|
3
|
Zhang M, Zhao Y, Umar A, Zhang H, Yang L, Huang J, Long Y, Yu Z. Comparative analysis of microbial composition and functional characteristics in dental plaque and saliva of oral cancer patients. BMC Oral Health 2024; 24:411. [PMID: 38575895 PMCID: PMC10993480 DOI: 10.1186/s12903-024-04181-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 03/25/2024] [Indexed: 04/06/2024] Open
Abstract
BACKGROUND The oral cavity is home to various ecological niches, each with its own unique microbial composition. Understanding the microbial communities and gene composition in different ecological niches within the oral cavity of oral cancer (OC) patients is crucial for determining how these microbial populations contribute to disease progression. METHODS In this study, saliva and dental plaque samples were collected from patients with OC. Metagenomic sequencing was employed to analyze the microbial community classification and functional composition of the different sample groups. RESULTS The results of the study revealed significant differences in both the function and classification of microbial communities between saliva and dental plaque samples. The diversity of microbial species in saliva was found to be higher compared to that in plaque samples. Notably, Actinobacteria were enriched in the dental plaque of OC patients. Furthermore, the study identified several inter-group differential marker species, including Prevotella intermedia, Haemophilus parahaemolyticus, Actinomyces radius, Corynebacterium matruchitii, and Veillonella atypica. Additionally, 1,353 differential genes were annotated into 23 functional pathways. Interestingly, a significant correlation was observed between differentially labeled species and Herpes simplex virus 1 (HSV-1) infection, which may be related to the occurrence and development of cancer. CONCLUSIONS Significant differences in the microbial and genetic composition of saliva and dental plaque samples were observed in OC patients. Furthermore, pathogenic bacteria associated with oral diseases were predominantly enriched in saliva. The identification of inter-group differential biomarkers and pathways provide insights into the relationship between oral microbiota and the occurrence and development of OC.
Collapse
Affiliation(s)
- Man Zhang
- Translational Medicine Center, Department of Head and Neck Surgery, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Yiming Zhao
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Abdulrahim Umar
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Hailin Zhang
- Translational Medicine Center, Department of Head and Neck Surgery, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Lirong Yang
- Translational Medicine Center, Department of Head and Neck Surgery, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Jing Huang
- Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
| | - Ying Long
- Translational Medicine Center, Department of Head and Neck Surgery, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.
| | - Zheng Yu
- Human Microbiome and Health Group, Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China.
| |
Collapse
|
4
|
Zhang W, Jiang M, Liao X, Li Y, Xin S, Yang L, Xin Y, Umar A, Lu J. IFIT3 inhibits Epstein-Barr virus reactivation via upregulating innate immunity. J Med Virol 2023; 95:e29237. [PMID: 37994186 DOI: 10.1002/jmv.29237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 10/29/2023] [Accepted: 10/30/2023] [Indexed: 11/24/2023]
Abstract
Epstein-Barr virus (EBV), a member of the γ-herpesvirus family, can establish latent infection in B lymphocytes and certain epithelial cells after primary infection. Under certain circumstances, EBV can enter into lytic replication. However, the regulation of EBV latent-lytic infection remains largely unclear. The important immune molecule, interferon-induced protein with tetratricopeptide repeats 3 (IFIT3), was upregulated in EBV latently infected cells. When the lytic replication of EBV was induced, the expression of IFIT3 was further increased. In turn, IFIT3 overexpression dramatically inhibited the lytic replication of EBV, while IFIT3 knockdown facilitated EBV lytic replication. Moreover, upon the lytic induction, the ectopic IFIT3 expression promoted the activation of the interferon (IFN) pathway, including the production of IFN-stimulated genes (ISGs), IFNB1, and the phosphorylation of IFN-regulatory factor 3 (IRF3). In contrast, the depletion of IFIT3 led to decreased ISGs and IFNB1 expression. Mechanically, IFIT3 inhibited EBV lytic replication through IFN signaling. This study revealed that the host innate immune-related factor IFIT3 played an important role in regulating EBV latent-lytic homeostasis. The results implied that EBV has evolved well to utilize host factors to maintain latent infection.
Collapse
Affiliation(s)
- Wentao Zhang
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Mingjuan Jiang
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Xuefei Liao
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Yanling Li
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Shuyu Xin
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Li Yang
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Yujie Xin
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Abdulrahim Umar
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| | - Jianhong Lu
- Department of Nuclear Medicine, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, Hunan, China
- NHC Key Laboratory of Carcinogenesis, The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Central South University, Changsha, Hunan, China
| |
Collapse
|
5
|
Umar A, Shi Z, Khlil A, Farouk Z. Industrial manipulator dynamic parameter estimation using mutating particle swarm optimization (Mupso). Nig J Tech 2021. [DOI: 10.4314/njt.v40i4.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This work aims at developing a dynamic model and estimating the unknown parameters of the first three joints (at the arm) of a 6 degree of freedom industrial robot manipulator, a finite Fourier series algorithm was used to design an excitation trajectory, a mutating particle swarm optimization algorithm was used to optimise the parameters of the Fourier series thereby minimizing the condition number of the observation matrix, and a linear least-squares methods was implemented for estimating the unknown dynamic parameters of the manipulator. A mutation function was implemented to break the algorithm out of stagnation. Out of the thirty unknown parameters at the industrial manipulator arm, twenty were identified independently, two were identifiable in linear combinations, and the remaining eight parameters were unidentifiable. The mutating particle swarm optimization algorithm dominated other algorithms and was found suitable for robot dynamic analysis.
Collapse
|
6
|
Shittu A, Mohammed J, Umar A. Correlate of respiratory symptoms, pulmonary function and functional capacity in sickle cell anaemia. Physiotherapy 2020. [DOI: 10.1016/j.physio.2020.03.227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
7
|
Manko M, Mohammed MF, Bello AK, Egbegbedia P, Sambo SA, Osanyibofu E, Umar A, Shehu A, Suleiman DE, Mustapha SK. Crohn’s disease with pyoderma gangrenosum in a patient in northern Nigeria: A case report. Niger J Med 2020. [DOI: 10.4103/1115-2613.284883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
|
8
|
Umar A, Raghupathi W. Upper-level Ontologies for Health Information Systems. Methods Inf Med 2018; 50:285-95. [DOI: 10.3414/me0519] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Accepted: 06/02/2010] [Indexed: 11/09/2022]
Abstract
SummaryObjectives: We examine the potential of archetype patterns for upper-level ontology development in health information systems (HISs).Methods: Archetype patterns, based on the integration of archetype concepts and design patterns, are conceptualized and developed for ontology in the HIS domain. The UML provides the underlying modeling support.Results: We argue in favor of the archetype pattern providing models for upper-level ontologies in HIS. This, in turn, has the potential to offer a foundation for interoperability across HIS applications and enterprises. Our research also shows the limitations of current ontology development methods as well as the challenges faced in archetype pattern development. The framework has potential for general, widespread usage. Overall, this approach supports ontology development in HIS.Conclusions: The research demonstrates the applicability of archetype patterns to ontology development in HIS. While numerous ontologies exist in biomedicine, there are few well-developed ontologies for general healthcare. Properly modeled, archetype patterns have potential to reconcile the differences in high-level design views across health care inter-enterprises. Future research can focus on governance, standards and tools for archetype patterns, as well as development of a comprehensive set of high-level healthcare archetype patterns.
Collapse
|
9
|
Yaro A, Salisu S, Umar A, Musa M. Multiangulation position estimation performance analysis using a Bartlett’s Beamforming Method. Nig J Tech 2018. [DOI: 10.4314/njt.v36i4.23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
10
|
Haque R, Umar A, Alavi Z. ASYMPTOMATIC PERSISTENT EOSINOPHILIA IN AN ELDERLY PATIENT WITH SURGICAL MESH. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.3141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- R. Haque
- Division of Geriatrics, Michigan State University, East Lansing, Michigan,
| | - A. Umar
- Dow Medical University, Karachi, Pakistan
| | - Z. Alavi
- Division of Geriatrics, Michigan State University, East Lansing, Michigan,
| |
Collapse
|
11
|
Ogbonna C, Ogbonna A, Onyimba I, Itelima J, Umar A, Onyezili N, Istifanus M. Combined Anti-diabetic Effects of Extracts of Artemisia annua var. chiknensis (CBGE/CHNA/09/LTNGS/G) and Each of Three Other Plants (Momordica charantia Linn. Vernonia amygdalina Del. and Aegle marmelos Correa) Traditionally Used in Nigeria for the Treatment of Diabetes. ACTA ACUST UNITED AC 2017. [DOI: 10.9734/jsrr/2017/36375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
12
|
Akpaniwo GM, Boynes S, Danfulani M, Chigozie NI, Umar A. Should MRI replace mammography as the initial screening modality for asymptomatic women aged 18 – 45 years at high risk of developing breast cancer? A systematic review. Asian J Med Sci 2016. [DOI: 10.3126/ajms.v7i5.14743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background: Breast cancer occurs in both men and women, although it is more prevalent among women. Mammography is generally the diagnostic imaging modality of choice, but it is limited in the detection of breast cancer in young women, aged 18-45 years due to the dense nature of their breast tissue.Aims and Objectives: This review explores whether MRI should replace mammography as the initial screening modality for asymptomatic women, aged 18-45 years at high risk of developing breast cancer. Materials and Methods: A systematic review of the literature was undertaken. A search of Medline, Pubmed central, Cinahl and Google scholar for English language literature from 2004 to 2015 was undertaken. Also a review of reference lists, author searching and review of NICE evidence base for exiting guidelines was done. Included studies were assessed for bias using STARD quality assessment tool and data were extracted systematically using a purposefully designed data extraction form. Result: From the seven included studies, 179 participants of the total population had breast cancer and a total of 199 breast cancer was detected by both modality used. MRI detected a total 148 breast cancers compared to 78 detected by mammography, and 10 interval cancer was reported. Sensitivity estimate from the included studies ranged from 25% to 100% while specificity ranged from 79% to 99%. MRI detected more breast cancer but had a moderate specificity compared to mammography as reported in the literature. Conclusion: In the absence of contraindication and accessibility, MRI should be used as the initial screening modality for asymptomatic women aged 18 – 45 years, at high risk of developing breast cancer. Asian Journal of Medical Sciences Vol.7(5) 2016 1-9
Collapse
|
13
|
Kesieme EB, Arekhandia BJ, Inuwa IM, Akpayak IC, Ekpe EE, Olawoye OA, Umar A, Awunor NS, Amadi EC, Ofoegbu IJ. Knowledge and practice of prophylaxis of deep venous thrombosis: A survey among Nigerian surgeons. Niger J Clin Pract 2016; 19:170-4. [PMID: 26856276 DOI: 10.4103/1119-3077.175961] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Venous thromboembolism is a potentially dangerous condition that can lead to preventable morbidity and mortality among surgical patients. OBJECTIVES We aimed to determine the knowledge and practice of surgeons practising in Tertiary Hospitals in Nigeria about prophylaxis of deep vein thrombosis (DVT). MATERIALS AND METHODS Eight Tertiary Institutions were selected from institutions in the geopolitical regions of the country by simple random sampling using balloting method. A semi-structured questionnaire was administered, and the response was obtained from 105 out of 254 surgeons. RESULTS The mean knowledge score was 5.81 ± 1.67, and only 33.3% have good knowledge about DVT prophylaxis. No statistical difference was observed between the different groups of surgeons. The mean practice score was 5.19 ± 1.8 and only 20% of surgeons have a good practice of DVT prophylaxis. The majority (90.5%) have encountered DVT whereas 83.5% have encountered pulmonary embolism in their practice. Most commonly encountered risk factors include prolonged immobility, advanced age, and pelvic surgery. Only 13.3% have used Well's score in the clinical evaluation of their patients. The prophylactic modality adopted varies, but most surgeons (77%) utilized both the pharmacological and mechanical methods. Low molecular weight heparin is the commonly used chemoprophylactic agent while a combination of early ambulation and limb physiotherapy is the most commonly preferred mechanical method of thromboprophylaxis. CONCLUSION There is a deficiency in the knowledge and practice of DVT prophylaxis among surgeons in Nigeria. There is a need to improve both the knowledge and practice by introducing institutional guidelines or protocol for DVT prophylaxis for surgical patients.
Collapse
Affiliation(s)
- E B Kesieme
- Department of Surgery, Irrua Specialist Teaching Hospital, Irrua, Edo, Nigeria
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Kaushal D, Rana D, Syal V, Chauhan S, Umar A. Micellar solubilization of Furosemide — Influence of cetyltrimethylammonium bromide in water–methanol mixture. J Mol Liq 2015. [DOI: 10.1016/j.molliq.2015.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
15
|
Cuzick J, Thorat MA, Bosetti C, Brown PH, Burn J, Cook NR, Ford LG, Jacobs EJ, Jankowski JA, La Vecchia C, Law M, Meyskens F, Rothwell PM, Senn HJ, Umar A. Estimates of benefits and harms of prophylactic use of aspirin in the general population. Ann Oncol 2015; 26:47-57. [PMID: 25096604 PMCID: PMC4269341 DOI: 10.1093/annonc/mdu225] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/14/2014] [Accepted: 06/09/2014] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Accumulating evidence supports an effect of aspirin in reducing overall cancer incidence and mortality in the general population. We reviewed current data and assessed the benefits and harms of prophylactic use of aspirin in the general population. METHODS The effect of aspirin for site-specific cancer incidence and mortality, cardiovascular events was collated from the most recent systematic reviews. Studies identified through systematic Medline search provided data regarding harmful effects of aspirin and baseline rates of harms like gastrointestinal bleeding and peptic ulcer. RESULTS The effects of aspirin on cancer are not apparent until at least 3 years after the start of use, and some benefits are sustained for several years after cessation in long-term users. No differences between low and standard doses of aspirin are observed, but there were no direct comparisons. Higher doses do not appear to confer additional benefit but increase toxicities. Excess bleeding is the most important harm associated with aspirin use, and its risk and fatality rate increases with age. For average-risk individuals aged 50-65 years taking aspirin for 10 years, there would be a relative reduction of between 7% (women) and 9% (men) in the number of cancer, myocardial infarction or stroke events over a 15-year period and an overall 4% relative reduction in all deaths over a 20-year period. CONCLUSIONS Prophylactic aspirin use for a minimum of 5 years at doses between 75 and 325 mg/day appears to have favourable benefit-harm profile; longer use is likely to have greater benefits. Further research is needed to determine the optimum dose and duration of use, to identify individuals at increased risk of bleeding, and to test effectiveness of Helicobacter pylori screening-eradication before starting aspirin prophylaxis.
Collapse
Affiliation(s)
- J Cuzick
- Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
| | - M A Thorat
- Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK
| | - C Bosetti
- Department of Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche 'Mario Negri', Milan, Italy
| | - P H Brown
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - J Burn
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - N R Cook
- Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston
| | - L G Ford
- Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda
| | - E J Jacobs
- Epidemiology Research Program, American Cancer Society, Atlanta, USA
| | - J A Jankowski
- Centre for Biomedical Research-Translational and Stratified Medicine, Peninsula Schools of Medicine and Dentistry, Plymouth University, Plymouth; Centre for Digestive Diseases, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, London, UK
| | - C La Vecchia
- Department of Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche 'Mario Negri', Milan, Italy; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - M Law
- Centre for Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK
| | - F Meyskens
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, USA
| | - P M Rothwell
- Stroke Prevention Research Unit, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, UK
| | - H J Senn
- Tumor and Breast Center ZeTuP, St Gallen, Switzerland
| | - A Umar
- Gastrointestinal and Other Cancers Research Group, Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda, USA
| |
Collapse
|
16
|
Aidenagbon G, Adeusi O, Akilah J, Umar A. Improving quality through process assessments during mass distribution campaigns of Long Lasting Insecticidal Nets (LLINs) in Nigeria: Studies from four states. Int J Infect Dis 2014. [DOI: 10.1016/j.ijid.2014.03.647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
17
|
Alhassan AM, Abdullahi MI, Uba A, Umar A. Prenylation of Aromatic Secondary Metabolites: A New Frontier for Development of Novel Drugs. TROP J PHARM RES 2014. [DOI: 10.4314/tjpr.v13i2.22] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
18
|
|
19
|
Kaushal D, Rana D, Chauhan M, Umar A, Chauhan S. The effect of sodium dodecyl sulphate on Furosemide — A cardiovascular drug in water–methanol at different temperature. J Mol Liq 2013. [DOI: 10.1016/j.molliq.2013.09.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
20
|
|
21
|
Ogoina D, Umar A, Obiako OR. Dermatomyositis associated with HIV-1 infection in a Nigerian adult female: a case report. Afr Health Sci 2012; 12:74-76. [PMID: 23066424 PMCID: PMC3462510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
Human immunodeficiency virus (HIV) infection has been implicated as a trigger for various autoimmune diseases, one of which is dermatomyositis. This is a very rare autoimmune disease characterised by myopathy, typical cutaneous signs and variable systemic manifestations. To our knowledge, the association of this rare disease with HIV infection has not been previously reported in Nigeria. We therefore decided to report the case of a 40 year old HIV-1 infected Nigerian female who presented to us with muscle, skin, and systemic manifestations of dermatomyositis. Our aim is to show the effect of HIV infection, as well as HAART-induced immune reconstitution on the clinical course of dermatomyositis.
Collapse
Affiliation(s)
- D Ogoina
- Department of Medicine, Niger Delta University, Wilberforce Island, Amasomma, Bayelsa State, Nigeria.
| | | | | |
Collapse
|
22
|
Braakman R, Jaremko M, Burgers P, Stingl C, Luider T, Look M, Martens J, Foekens J, Umar A. 5082 POSTER Identification of Protein Markers Predicting Chemotherapy Resistance in Breast Cancer. Eur J Cancer 2011. [DOI: 10.1016/s0959-8049(11)71524-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
23
|
Iliyasu Z, Umar A, Aminu G, Jahun S. Perception and predictors of insecticide-treated net use in a rural Northern Nigerian community. Sahel Med J 2011. [DOI: 10.4314/smj2.v13i4.67505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
24
|
Adelowo OO, Umar A. Juvenile idiopathic arthritis among Nigerians: a case study. Clin Rheumatol 2010; 29:757-61. [PMID: 20195880 DOI: 10.1007/s10067-010-1401-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 01/14/2010] [Accepted: 02/01/2010] [Indexed: 10/19/2022]
Abstract
Juvenile idiopathic arthritis (JIA) has rarely been reported among Black Africans. This retrospective case study was part of an audit of cases presenting to a private practice rheumatology clinic in Lagos, Nigeria. The objective of this study was to determine the clinical, laboratory, and radiographic features of patients with JIA, as well as to highlight their management. A total of 23 cases (F-16:M-7) were seen over an 8.5-year period. Polyarticular presentation was the commonest while systemic onset was the least. The mean age at presentation was 12.7 years. Most of the patients presented late with mean of 3.7 years before presentation. The knees and ankles were most commonly involved. ESR was elevated in most of the cases. Rheumatoid factor and Antinuclear antibodies were invariably negative. Treatments were with standard drugs. Although JIA is uncommonly seen in our population, the clinical and laboratory features are similar as elsewhere, though there are some differences.
Collapse
Affiliation(s)
- Olufemi O Adelowo
- Rheumatology Unit, Department of Medicine, Olabisi Onabanjo University Teaching Hospital, Sagamu, Ogun State, Nigeria.
| | | |
Collapse
|
25
|
Ruijtenbeek R, Umar A, van Houten L, Hilhorst R, Foekens JA, de Wijn R, Martens JW. Differential protein kinase activity in ER-positive and ER-negative breast cancer. J Clin Oncol 2009. [DOI: 10.1200/jco.2009.27.15_suppl.e22142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
e22142 Background: Specific protein tyrosine kinases (PTKs) promote cancer progression and are potential drug targets. The presence of the estrogen receptor (ER) is an important criterion in deciding on treatment of patients with breast cancer. Since PTKs can affect the tumors' receptor function, we investigated in our first proof-of-principle study whether it is possible to discriminate ER-positive (ER+) from ER-negative (ER-) tumors based on PTK activity using microarrays containing many PTK peptide substrates. Methods: Cryosections of 12 ER+ and 12 ER- breast tumors were lysed in the presence of appropriate protease and phosphatase inhibitors. The protein kinase activity in the lysates was monitored in vitro using PamChip peptide microarrays, which comprise of 253 PTK peptide substrates derived from known human phosphorylation sites. Peptide phosphorylation through active kinases can be monitored in samples in real time, using a fluorescently labeled phospho-tyrosine specific antibody. Results: Phosphorylation activity profiles were determined in quadruplicate using multiple independent sample preparations. Using ANOVA analysis, out of 253 peptides, several peptides with a different phosphorylation signal in ER+ and ER- samples were found: 22 with p < 0.02 including VEGFR1, 2 and 3 and ADAM9. Multivariate unsupervised analysis using Principle Component Analysis showed a clustering of ER+ samples vs. ER- samples. Predictive analysis was performed using Partial-Least Squares Discriminant Analysis without explicit feature selection. The prediction error obtained from within experiment cross validation was typically in the range 10–20%. The error rate for between experiment prediction was 20%. An average predictive profile was constructed in which peptides with a relatively large weight were included, e.g. ADAM9 and BCAR1. Conclusions: Using PamChip peptide microarrays we have shown that differences in protein kinase activity exist between ER+ and ER- breast tumors. Our in vitro assay is a promising tool to investigate the interplay between kinase and nuclear receptor mediated signaling, with potential relevance to patient selection for targeted therapies. No significant financial relationships to disclose.
Collapse
Affiliation(s)
- R. Ruijtenbeek
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - A. Umar
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - L. van Houten
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - R. Hilhorst
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - J. A. Foekens
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - R. de Wijn
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - J. W. Martens
- Pamgene Int. BV, 's- Hertogenbosch, Netherlands; Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| |
Collapse
|
26
|
Umar A, Karunagaran B, Suh EK, Hahn YB. Structural and optical properties of single-crystalline ZnO nanorods grown on silicon by thermal evaporation. Nanotechnology 2006; 17:4072-7. [PMID: 21727540 DOI: 10.1088/0957-4484/17/16/013] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The growth of perfectly hexagonal-shaped ZnO nanorods, with Zn-terminated (0001) facets bounded with [Formula: see text] surfaces, has been performed on nickel-coated Si(100) substrate via thermal evaporation using metallic zinc powder and oxygen. Detailed structural investigations confirmed that the synthesized nanorods are single crystalline with the wurtzite hexagonal phase and preferentially grow along the c-axis direction. Raman spectra of the as-grown ZnO nanorods showed an optical-phonon E(2) mode at 438 cm(-1), indicating that as-grown nanostructures are in good crystallinity with the wurtzite hexagonal phase. The ZnO nanorods were found to show strong band edge emission with very weak or no deep-level emission, as shown by photoluminescence measurements. The clear observation of free excitons at low temperatures (13-50 K) indicates that the as-grown ZnO nanorods are of high quality.
Collapse
Affiliation(s)
- A Umar
- School of Chemical Engineering and Technology, Nanomaterials Processing Research Centre, Chonbuk National University, Jeonju 561-756, Korea
| | | | | | | |
Collapse
|
27
|
Umar A, Lee S, Im YH, Hahn YB. Flower-shaped ZnO nanostructures obtained by cyclic feeding chemical vapour deposition: structural and optical properties. Nanotechnology 2005; 16:2462-8. [PMID: 20818036 DOI: 10.1088/0957-4484/16/10/079] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Flower-shaped ZnO nanostructures were grown on Si(100) and Si(111) substrates by cyclic feeding chemical vapour deposition without the use of a metal catalyst. The structures obtained on the Si(100) substrate exhibited triangle-shaped leaves with lengths and diameters in the ranges 300-400 and 90-130 nm, respectively. Uniformly shaped leaves with hexagonal facets originating from one centre were observed on the flower-shaped structures grown on the Si(111) substrate. Transmission electron microscopy and selected area electron diffraction patterns showed that these structures are highly crystalline, with the wurtzite hexagonal phase, and preferentially oriented in the c-axis direction. Unlike star-shaped ZnO nanostructures grown on Au-coated silicon substrates, the flower-shaped nanostructures showed sharp and strong UV emission at 378 nm and broad and weak green emission at 520 nm, indicating a good crystal quality and few structural defects.
Collapse
Affiliation(s)
- A Umar
- School of Chemical Engineering and Technology, Nanomaterials Processing Research Centre, Chonbuk National University, 664-14 Duckjin-Dong 1-Ga, Chonju 561-756, Republic of Korea
| | | | | | | |
Collapse
|
28
|
Abstract
More than one million Americans were expected to be diagnosed with cancer in 2003 (7a). Compelling experimental, epidemiological, and clinical evidence indicates that many cancers are preventable, especially because diet and nutrition are key factors in the modulation of cancer risk. The road to nutritional intervention in cancer prevention has led to successful trials as well as trials that did not reach their intended endpoints. This chapter reviews four case studies of trials, with two ending in success and two ending in null findings or adverse effects. The goal is to identify lessons learned from all four case studies and from the investigations of the complexities inherent to nutritional intervention trials. Additional insights are presented by the research addressing potential mechanisms underlying the endpoints of human trials. Future progress in nutrition and cancer prevention will require expertise from multidisciplinary teams to develop new knowledge about specific nutrients and dietary modifications within a framework of interaction between animal and human research.
Collapse
Affiliation(s)
- M R Forman
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
| | | | | | | |
Collapse
|
29
|
Umar A. RESPONSE: Re: Revised Bethesda Guidelines for Hereditary Nonpolyposis Colorectal Cancer (Lynch Syndrome) and Microsatellite Instability. J Natl Cancer Inst 2004. [DOI: 10.1093/jnci/djh281] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
30
|
|
31
|
Abstract
Chemoprevention science is in flux owing to rapid advances in postgenomic technology. We have witnessed enormous advances in the areas of early detection and molecular profiling of colorectal carcinogenesis; however, unique interpretive and technologic challenges persist. Neoplastic hallmarks must be iteratively tested and validated as markers of risk, targets for intervention, and/or markers of response in order to expedite the development of preventive interventions. In this review, we highlight several of the technologies that are revolutionizing our understanding of carcinogenesis and our approach to colorectal cancer prevention.
Collapse
Affiliation(s)
- A Umar
- Gastrointestinal & Other Cancers Research Group, National Cancer Institute, Division of Cancer Prevention, EPN, Bethesda, Maryland 20892-7317, USA
| | | | | |
Collapse
|
32
|
Watanabe Y, Haugen-Strano A, Umar A, Yamada K, Hemmi H, Kikuchi Y, Takano S, Shibata Y, Barrett JC, Kunkel TA, Koi M. Complementation of an hMSH2 defect in human colorectal carcinoma cells by human chromosome 2 transfer. Mol Carcinog 2000. [PMID: 11020245 DOI: 10.1002/1098-2744(200009)29:13.0.co;2-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The human colorectal tumor cell line LoVo has a homozygous deletion in the hMSH2 gene from exon 3 to exon 8, is deficient in mismatch repair (MMR) activity, and exhibits microsatellite instability. To determine whether the introduction of a wild type hMSH2 into LoVo restores MMR activity and stabilizes microsatellite loci, we transferred a chromosome 2 fragment containing hMSH2 into a homologous recombination-proficient chicken DT40/human hybrid (DT40 2C) and a human chromosome 2 in a mouse A9 hybrid to LoVo. Transfers of these chromosomes into LoVo resulted in LoVo both with and without a wild-type hMSH2. Complete correlation was found between the presence of the wild-type hMSH2 and hMSH2 expression, an increased stability in microsatellite loci, and competency in MMR. The hMSH2-positive LoVo hybrids also showed an increased sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine. This enhanced toxicity is associated with G(2) cell-cycle arrest followed by premature mitosis and cell death. These results suggest that hMSH2 may be responsible for complementing mutator and drug-resistant phenotypes in chromosome 2-transferred LoVo cells. To test whether the hMSH2 in DT40 2C cells can be modified by homologous recombination, we transfected DT40 2C with a targeting vector containing an hMSH2 exon 4 disrupted by the zeocin-resistant gene. The results showed that the hMSH2 locus in DT40 2C was efficiently targeted by an exogeneously transfected homologous sequence, suggesting that transfer of a modified hMSH2 from DT40 2C to LoVo via chromosome transfer could be used to determine the function of hMSH2.
Collapse
Affiliation(s)
- Y Watanabe
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Edelmann W, Umar A, Yang K, Heyer J, Kucherlapati M, Lia M, Kneitz B, Avdievich E, Fan K, Wong E, Crouse G, Kunkel T, Lipkin M, Kolodner RD, Kucherlapati R. The DNA mismatch repair genes Msh3 and Msh6 cooperate in intestinal tumor suppression. Cancer Res 2000; 60:803-7. [PMID: 10706084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Repair of mismatches in DNA in mammalian cells is mediated by a complex of proteins that are members of two highly conserved families of genes referred to as MutS and MutL homologues. Germline mutations in several members of these families, MSH2, MSH6, MLH1, and PMS2, but not MSH3, are responsible for hereditary non-polyposis colorectal cancer. To examine the role of MSH3, we generated a mouse with a null mutation in this gene. Cells from Msh3-/- mice are defective in repair of insertion/ deletion mismatches but can repair base-base mismatches. Msh3-/- mice develop tumors at a late age. When the Msh3-/- and Msh6-/- mutations are combined, the tumor predisposition phenotype is indistinguishable from Msh2-/- or Mlh1-/- mice. These results suggest that MSH3 cooperates with MSH6 in tumor suppression.
Collapse
Affiliation(s)
- W Edelmann
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Glaab WE, Risinger JI, Umar A, Barrett JC, Kunkel TA, Tindall KR. Resistance to 6-thioguanine in mismatch repair-deficient human cancer cell lines correlates with an increase in induced mutations at the HPRT locus. Carcinogenesis 1998; 19:1931-7. [PMID: 9855005 DOI: 10.1093/carcin/19.11.1931] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although the resistance to the cytotoxic response of certain DNA damaging agents has been well characterized in cells deficient in mismatch repair, little is known about how such resistance affects mutagenesis. Using human cancer cell lines defective in mismatch repair (MMR) and complementary cell lines in which the MMR defects were corrected by chromosome transfer, we present the cytotoxic effect and the mutagenic response at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus following exposure to the chemotherapeutic agent, 6-thioguanine (6-TG). Upon exposure to 6-TG, there was a differential cytotoxic response. The MMR-deficient cells were resistant to 6-TG exposure up to 5 microM, whereas the MMR-proficient cell lines were significantly more sensitive at the same levels of exposure. Furthermore, the mutagenic response at HPRT induced by 6-TG was substantially increased in the MMR-deficient lines relative to the MMR-proficient cell lines. These findings support the notion that cytotoxicity to 6-TG is mediated through functional MMR and that resistance to the cytotoxic effects of 6-TG is directly associated with an increase in induced mutations in MMR-defective cells. These data suggest that the use of 6-TG as a chemotherapeutic agent may result in the selection of MMR-defective cells, thereby predisposing the patient to an increased risk for developing secondary tumors.
Collapse
Affiliation(s)
- W E Glaab
- Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | | | | | | | | | | |
Collapse
|
35
|
Glaab WE, Risinger JI, Umar A, Kunkel TA, Barrett JC, Tindall KR. Characterization of distinct human endometrial carcinoma cell lines deficient in mismatch repair that originated from a single tumor. J Biol Chem 1998; 273:26662-9. [PMID: 9756907 DOI: 10.1074/jbc.273.41.26662] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of specific mismatch repair (MMR) gene products was examined by observing several phenotypic end points in two MMR-deficient human endometrial carcinoma cell lines that were originally isolated from the same tumor. The first cell line, HEC-1-A, contains a nonsense mutation in the hPMS2 gene, which results in premature termination and a truncated hPMS2 protein. In addition, HEC-1-A cells carry a splice mutation in the hMSH6 gene and lack wild-type hMSH6 protein. The second cell line, HEC-1-B, possesses the same defective hMSH6 locus. However, HEC-1-B cells are heterozygous at the hPMS2 locus; that is, along with carrying the same nonsense mutation in hPMS2 as in HEC-1-A, HEC-1-B cells also contain a wild-type hPMS2 gene. Initial recognition of mismatches in DNA requires either the hMSH2/hMSH6 or hMSH2/hMSH3 heterodimer, with hPMS2 functioning downstream of damage recognition. Therefore, cells defective in hPMS2 should completely lack MMR (HEC-1-A), whereas cells mutant in hMSH6 only (HEC-1-B) can potentially repair damage via the hMSH2/hMSH3 heterodimer. The data presented here in HEC-1-B cells illustrate (i) the reduction of instability at microsatellite sequences, (ii) a significant decrease in frameshift mutation rate at HPRT, and (iii) the in vitro repair of looped substrates, relative to HEC-1-A cells, illustrating the repair of frameshift intermediates by hMSH2/hMSH3 heterodimer. Furthermore, the role of hMSH2/hMSH3 heterodimer in the repair of base:base mismatches is supported by observing the reduction in base substitution mutation rate at HPRT in HEC-1-B cells (hMSH6-defective but possessing wild-type hPMS2), as compared with HEC-1-A (hMSH6/hPMS2-defective) cells. These data support a critical role for hPMS2 in human MMR, while further defining the role of the hMSH2/hMSH3 heterodimer in maintaining genomic stability in the absence of a wild-type hMSH2/hMSH6 heterodimer.
Collapse
Affiliation(s)
- W E Glaab
- Laboratory of Environmental Carcinogenesis and Mutagenesis, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
| | | | | | | | | | | |
Collapse
|
36
|
Vaisman A, Varchenko M, Umar A, Kunkel TA, Risinger JI, Barrett JC, Hamilton TC, Chaney SG. The role of hMLH1, hMSH3, and hMSH6 defects in cisplatin and oxaliplatin resistance: correlation with replicative bypass of platinum-DNA adducts. Cancer Res 1998; 58:3579-85. [PMID: 9721864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Defects in mismatch repair are associated with cisplatin resistance, and several mechanisms have been proposed to explain this correlation. It is hypothesized that futile cycles of translesion synthesis past cisplatin-DNA adducts followed by removal of the newly synthesized DNA by an active mismatch repair system may lead to cell death. Thus, resistance to platinum-DNA adducts could arise through loss of the mismatch repair pathway. However, no direct link between mismatch repair status and replicative bypass ability has been reported. In this study, cytotoxicity and steady-state chain elongation assays indicate that hMLH1 or hMSH6 defects result in 1.5-4.8-fold increased cisplatin resistance and 2.5-6-fold increased replicative bypass of cisplatin adducts. Oxaliplatin adducts are not recognized by the mismatch repair complex, and no significant differences in bypass of oxaliplatin adducts in mismatch repair-proficient and -defective cells were found. Defects in hMSH3 did not alter sensitivity to, or replicative bypass of, either cisplatin or oxaliplatin adducts. These observations support the hypothesis that mismatch repair defects in hMutL alpha and hMutS alpha, but not in hMutS beta, contribute to increased net replicative bypass of cisplatin adducts and therefore to drug resistance by preventing futile cycles of translesion synthesis and mismatch correction.
Collapse
Affiliation(s)
- A Vaisman
- Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill 27599-7260, USA
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Risinger JI, Umar A, Glaab WE, Tindall KR, Kunkel TA, Barrett JC. Single gene complementation of the hPMS2 defect in HEC-1-A endometrial carcinoma cells. Cancer Res 1998; 58:2978-81. [PMID: 9679958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Results from the analysis of human tumor cell lines with mutations in DNA mismatch repair genes have contributed to the understanding of the functions of these gene products in DNA mismatch repair, microsatellite instability, cell cycle checkpoint control, transcription-coupled nucleotide excision repair, and resistance to cytotoxic agents. However, complementation of human DNA mismatch repair defects by introduction of a single cloned gene or cDNA, which would serve to directly prove or disprove their involvement in these processes, has not been accomplished. Here, we introduce a wild-type copy of the hPMS2 cDNA by stable transfection into the PMS2 mutant HEC-1-A cell line. HEC-1-A cells expressing wild-type hPMS2 exhibit increased microsatellite stability, have a reduced mutation rate at the endogenous hypoxanthine phosphoribosyltransferase locus and extracts from these cells are able to perform strand-specific mismatch repair. These results demonstrate that the hPMS2 gene is integral to the maintenance of genome stability.
Collapse
Affiliation(s)
- J I Risinger
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | |
Collapse
|
38
|
Abstract
The study of the multiple functions of mismatch repair genes in humans is being facilitated by the use of human tumor cell lines carrying defined MMR gene mutations. Such cell lines have elevated spontaneous mutation rates and may accumulate mutations in other genes, some of which could be causally related to the phenotypes of these cells. One approach to establish a cause-effect relationship between a MMR gene defect and a phenotype is to determine if that phenotype is reversed when a normal chromosome carrying a wild-type MMR gene is introduced by microcell fusion. This approach has the advantage of presenting the gene in its natural chromosomal environment with normal regulatory controls and at a reasonable dosage. The approach also limits candidate genes to only those encoded by the introduced chromosome and not elsewhere in the genome. Here we review studies demonstrating that hMSH2, hMSH3, hMSH6 and hMLH1 gene defects can each be complemented by transferring human chromosome 2, 5, 2 or 3, respectively. These transfers restore MMR activity, sensitivity to killing by MNNG, stability to microsatellite sequences and low spontaneous HPRT gene mutation rates.
Collapse
Affiliation(s)
- K R Tindall
- Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Winter DB, Phung QH, Umar A, Baker SM, Tarone RE, Tanaka K, Liskay RM, Kunkel TA, Bohr VA, Gearhart PJ. Altered spectra of hypermutation in antibodies from mice deficient for the DNA mismatch repair protein PMS2. Proc Natl Acad Sci U S A 1998; 95:6953-8. [PMID: 9618520 PMCID: PMC22699 DOI: 10.1073/pnas.95.12.6953] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/1998] [Indexed: 02/07/2023] Open
Abstract
Mutations are introduced into rearranged Ig variable genes at a frequency of 10(-2) mutations per base pair by an unknown mechanism. Assuming that DNA repair pathways generate or remove mutations, the frequency and pattern of mutation will be different in variable genes from mice defective in repair. Therefore, hypermutation was studied in mice deficient for either the DNA nucleotide excision repair gene Xpa or the mismatch repair gene Pms2. High levels of mutation were found in variable genes from XPA-deficient and PMS2-deficient mice, indicating that neither nucleotide excision repair nor mismatch repair pathways generate hypermutation. However, variable genes from PMS2-deficient mice had significantly more adjacent base substitutions than genes from wild-type or XPA-deficient mice. By using a biochemical assay, we confirmed that tandem mispairs were repaired by wild-type cells but not by Pms2(-/-) human or murine cells. The data indicate that tandem substitutions are produced by the hypermutation mechanism and then processed by a PMS2-dependent pathway.
Collapse
Affiliation(s)
- D B Winter
- Laboratory of Molecular Genetics, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Herman JG, Umar A, Polyak K, Graff JR, Ahuja N, Issa JP, Markowitz S, Willson JK, Hamilton SR, Kinzler KW, Kane MF, Kolodner RD, Vogelstein B, Kunkel TA, Baylin SB. Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma. Proc Natl Acad Sci U S A 1998; 95:6870-5. [PMID: 9618505 PMCID: PMC22665 DOI: 10.1073/pnas.95.12.6870] [Citation(s) in RCA: 1339] [Impact Index Per Article: 51.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inactivation of the genes involved in DNA mismatch repair is associated with microsatellite instability (MSI) in colorectal cancer. We report that hypermethylation of the 5' CpG island of hMLH1 is found in the majority of sporadic primary colorectal cancers with MSI, and that this methylation was often, but not invariably, associated with loss of hMLH1 protein expression. Such methylation also occurred, but was less common, in MSI- tumors, as well as in MSI+ tumors with known mutations of a mismatch repair gene (MMR). No hypermethylation of hMSH2 was found. Hypermethylation of colorectal cancer cell lines with MSI also was frequently observed, and in such cases, reversal of the methylation with 5-aza-2'-deoxycytidine not only resulted in reexpression of hMLH1 protein, but also in restoration of the MMR capacity in MMR-deficient cell lines. Our results suggest that microsatellite instability in sporadic colorectal cancer often results from epigenetic inactivation of hMLH1 in association with DNA methylation.
Collapse
Affiliation(s)
- J G Herman
- The Johns Hopkins Oncology Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
Three human genes, hMSH2, hMSH3, and hMSH6, are homologues of the bacterial MutS gene whose products bind DNA mismatches to initiate strand-specific repair of DNA replication errors. Several studies suggest that a complex of hMSH2 x hMSH6 (hMutSalpha) functions primarily in repair of base x base mismatches or single extra bases, whereas a hMSH2 x hMSH3 complex (hMutSbeta) functions chiefly in repair of heteroduplexes containing two to four extra bases. In the present study, we compare results with a tumor cell line (HHUA) that is mutant in both hMSH3 and hMSH6 to results with derivative clones containing either wild-type hMSH3 or wild-type hMSH6, introduced by microcell-mediated transfer of chromosome 5 or 2, respectively. HHUA cells exhibit marked instability at 12 different microsatellite loci composed of repeat units of 1 to 4 base pairs. Compared to normal cells, HHUA cells have mutation rates at the HPRT locus that are elevated 500-fold for base substitutions and 2400-fold for single-base frameshifts. Extracts of HHUA cells are defective in strand-specific repair of substrates containing base x base mismatches or 1-4 extra bases. Transfer of either chromosome 5 (hMSH3) or 2 (hMSH6) into HHUA cells partially corrects instability at the microsatellite loci and also the substitution and frameshift mutator phenotypes at the HPRT locus. Extracts of these lines can repair some, but not all, heteroduplexes. The combined mutation rate and mismatch repair specificity data suggest that both hMSH3 and hMSH6 can independently participate in repair of replication errors containing base x base mismatches or 1-4 extra bases. Thus, these two gene products share redundant roles in controlling mutation rates in human cells.
Collapse
Affiliation(s)
- A Umar
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | |
Collapse
|
42
|
Glaab WE, Risinger JI, Umar A, Barrett JC, Kunkel TA, Tindall KR. Cellular resistance and hypermutability in mismatch repair-deficient human cancer cell lines following treatment with methyl methanesulfonate. Mutat Res 1998; 398:197-207. [PMID: 9626980 DOI: 10.1016/s0027-5107(98)00004-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Resistance to the cytotoxic effects of S(N)1 alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU) is well established in mismatch repair-defective cells, however, little is known about the cellular response to S(N)2 alkylating agents in these cells. Here we describe the cytotoxic response and the mutagenic response at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus to the S(N)2 alkylating agent methyl methanesultfonate (MMS) in human cancer cell lines defective in mismatch repair (MMR). Our findings suggest that cytotoxicity to MMS is mediated through MMR, as indicated by an increased resistance to MMS in MMR-deficient cells. Cells in which specific MMR-gene defects were complemented by chromosome transfer were generally more sensitive to the cytotoxic effects of MMS. Additionally, the induced mutant frequency at HPRT following exposure to MMS is significantly increased in MMR-deficient lines. These findings suggest that resistance to S(N)2 alkylation damage is mediated by MMR genes, and that resistance to such damage in MMR-defective cells correlates with an increase in genomic mutations. The results are consistent with the hypothesis that abasic sites may be substrates for repair involving MMR-gene products in human cells.
Collapse
Affiliation(s)
- W E Glaab
- Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | | | | | | | | | | |
Collapse
|
43
|
Pettersson A, Prinz T, Umar A, van der Biezen J, Tommassen J. Molecular characterization of LbpB, the second lactoferrin-binding protein of Neisseria meningitidis. Mol Microbiol 1998; 27:599-610. [PMID: 9489671 DOI: 10.1046/j.1365-2958.1998.00707.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The lbpA gene of Neisseria meningitidis encodes an outer membrane lactoferrin-binding protein and shows homology to the transferrin-binding protein, TbpA. Previously, we have detected part of an open reading frame upstream of lbpA. The putative product of this open reading frame, tentatively designated lbpB, showed homology to the transferrin-binding protein TbpB, suggesting that the lactoferrrin receptor, like the transferrin receptor, consists of two proteins. The complete nucleotide sequence of lbpB was determined. The gene encodes a 77.5 kDa protein, probably a lipoprotein, with homology, 33% identity to the TbpB of N. meningitidis. A unique feature of LbpB is the presence of two stretches of negatively charged residues, which might be involved in lactoferrin binding. Antisera were raised against synthetic peptides corresponding to the C-terminal part of the putative protein and used to demonstrate that the gene is indeed expressed. Consistent with the presence of a putative Fur binding site upstream of the lbpB gene, expression of both LbpA and LbpB was proved to be iron regulated in Western blot experiments. The LbpB protein appeared to be less stable than TbpB in SDS-containing sample buffer. Isogenic mutants lacking either LbpA or LbpB exhibited a reduced ability to bind lactoferrin. In contrast to the lbpB mutant, the lbpA mutant was completely unable to use lactoferrin as a sole source of iron.
Collapse
Affiliation(s)
- A Pettersson
- Department of Molecular Cell Biology and Institute of Biomembranes, Utrecht University, The Netherlands.
| | | | | | | | | |
Collapse
|
44
|
Edelmann W, Yang K, Umar A, Heyer J, Lau K, Fan K, Liedtke W, Cohen PE, Kane MF, Lipford JR, Yu N, Crouse GF, Pollard JW, Kunkel T, Lipkin M, Kolodner R, Kucherlapati R. Mutation in the mismatch repair gene Msh6 causes cancer susceptibility. Cell 1997; 91:467-77. [PMID: 9390556 DOI: 10.1016/s0092-8674(00)80433-x] [Citation(s) in RCA: 268] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mice carrying a null mutation in the mismatch repair gene Msh6 were generated by gene targeting. Cells that were homozygous for the mutation did not produce any detectable MSH6 protein, and extracts prepared from these cells were defective for repair of single nucleotide mismatches. Repair of 1, 2, and 4 nucleotide insertion/deletion mismatches was unaffected. Mice that were homozygous for the mutation had a reduced life span. The mice developed a spectrum of tumors, the most predominant of which were gastrointestinal tumors and B- as well as T-cell lymphomas. The tumors did not show any microsatellite instability. We conclude that MSH6 mutations, like those in some other members of the family of mismatch repair genes, lead to cancer susceptibility, and germline mutations in this gene may be associated with a cancer predisposition syndrome that does not show microsatellite instability.
Collapse
Affiliation(s)
- W Edelmann
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Umar A, Koi M, Risinger JI, Glaab WE, Tindall KR, Kolodner RD, Boland CR, Barrett JC, Kunkel TA. Correction of hypermutability, N-methyl-N'-nitro-N-nitrosoguanidine resistance, and defective DNA mismatch repair by introducing chromosome 2 into human tumor cells with mutations in MSH2 and MSH6. Cancer Res 1997; 57:3949-55. [PMID: 9307278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The human DNA mismatch repair genes hMSH2 and hMSH6 encode the proteins that, together, bind to mismatches to initiate repair of replication errors. Human tumor cells containing mutations in these genes have strongly elevated mutation rates in selectable genes and at microsatellite loci, although mutations in these genes cause somewhat different mutator phenotypes. These cells are also resistant to killing by certain drugs and are defective in mismatch repair. Because the elevated mutation rates in these cells may lead to mutations in additional genes that are causally related to the other defects, here we attempt to establish a cause-effect relationship between the hMSH2 and hMSH6 gene mutations and the observed phenotypes. The endometrial tumor cell line HEC59 contains mutations in both alleles of hMSH2. The colon tumor cell line HCT15 contains mutations in hMSH6 and also has a sequence change in a conserved region of the coding sequence for DNA polymerase delta, a replicative DNA polymerase. We introduced human chromosome 2 containing the wild-type hMSH2 and hMSH6 genes into HEC59 and HCT15 cells. Introduction of chromosome 2 to HEC59 cells restored microsatellite stability, sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine treatment, and mismatch repair activity. Transfer of chromosome 2 to HCT15 cells also reduced the mutation rate at the HPRT locus and restored sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine treatment and mismatch repair activity. The results demonstrate that the observed defects are causally related to mutations in genes on chromosome 2, probably hMSH2 or hMSH6, but are not related to sequence changes in other genes, including the gene encoding DNA polymerase delta.
Collapse
Affiliation(s)
- A Umar
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Bennett SE, Umar A, Oshima J, Monnat RJ, Kunkel TA. Mismatch repair in extracts of Werner syndrome cell lines. Cancer Res 1997; 57:2956-60. [PMID: 9230208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Werner syndrome (WS) is an autosomal recessive disease, the phenotype of which is a caricature of premature aging. WS cells and cell lines display several types of genetic instability, and WS patients have an increased risk of developing cancer. The WS locus (WRN) encodes a protein that shows significant sequence homology to the RecQ family of DNA helicases. Because a DNA helicase may function in DNA mismatch repair, we examined extracts of WS cell lines for mismatch repair activity. Extracts from four different WS lymphoblastoid cell lines containing different WRN mutations and from three within-pedigree control cell lines were all proficient in mismatch repair. In marked contrast, extracts from three independent WS fibroblastoid cell lines were deficient in repair of base-base and insertion/deletion mismatches. Extracts of one of these lines restored activity to extracts of mismatch repair-deficient tumor cells with defined mutations in hMSH2, hMSH3, hMSH6, hMLH1, or hPMS2. This suggests that the WRN mutation in this fibroblast line is not a dominant negative inhibitor of mismatch repair activity and that the repair defect does not reside in these five known mismatch repair genes. Defective mismatch repair in fibroblastoid but not lymphoblastoid cells is consistent with the possibility that WRN protein could have a cell type- and/or tissue-specific role in mismatch repair. Alternatively, a mutation in WRN could predispose cells to mutations in other genes required for mismatch repair activity, at least one of which could be an unknown gene.
Collapse
Affiliation(s)
- S E Bennett
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | |
Collapse
|
47
|
Khan MZ, Muhammad G, Umar A, Ali Khan S. A preliminary comparison of plasma fibrinogen concentrations, leukocyte numbers and erythrocyte sedimentation rate as non-specific indicators of inflammatory conditions in buffalo (Bubalis bubalis). Vet Res Commun 1997; 21:265-71. [PMID: 9151410 DOI: 10.1023/a:1005838809787] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The plasma fibrinogen concentration (Fib), total leukocyte count (TLC), neutrophil, lymphocyte and monocyte numbers, and the erythrocyte sedimentation rate (ESR) were determined in 153 buffaloes suffering from different clinical conditions. Fib increased significantly (p < 0.05) in chronic mastitis, pyrexia, pyometra, cutaneous abscesses, tail gangrene and acute indigestion, whereas in most of the other conditions studied it varied non-significantly. TLC increased significantly in chronic mastitis, pyrexia, endometritis, cutaneous abscesses and infected skin wounds. An increase in neutrophils was associated with an increased TLC. Numbers of lymphocytes varied non-significantly in most of the conditions. Monocytes decreased significantly in most of the acute conditions. ESR was significantly elevated in all clinical conditions. Significantly increased mean Fib values in the different conditions varied from 703 +/- 119 to 725 +/- 140 mg/dl, while the maximum individual value was 1510 mg/dl in a case of cutaneous myiasis. The significantly increased mean TLC ranged from 9.48 +/- 2.91 to 11.1 +/- 3.5 x 10(3)/microliter, while it was 21.7 x 10(3)/microliter in a case of meningitis. ESR values in sick buffaloes varied from 57 to 111 mm in the first hour.
Collapse
Affiliation(s)
- M Z Khan
- Department of Veterinary Pathology, University of Agriculture, Pakistan
| | | | | | | |
Collapse
|
48
|
Abstract
A two-hybrid system was used to screen yeast and human expression libraries for proteins that interact with mismatch repair proteins. PCNA was recovered from both libraries and shown in the case of yeast to interact with both MLH1 and MSH2. A yeast strain containing a mutation in the PCNA gene had a strongly elevated mutation rate in a dinucleotide repeat, and the rate was not further elevated in a strain also containing a mutation in MLH1. Mismatch repair activity was examined in human cell extracts using an assay that does not require DNA repair synthesis. Activity was inhibited by p21WAF1 or a p21 peptide, both of which bind to PCNA, and activity was restored to inhibited reactions by addition of PCNA. The data suggest a PCNA requirement in mismatch repair at a step preceding DNA resynthesis. The ability of PCNA to bind to MLH1 and MSH2 may reflect linkage between mismatch repair and replication and may be relevant to the roles of mismatch repair proteins in other DNA transactions.
Collapse
Affiliation(s)
- A Umar
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | | | |
Collapse
|
49
|
Risinger JI, Umar A, Boyd J, Berchuck A, Kunkel TA, Barrett JC. Mutation of MSH3 in endometrial cancer and evidence for its functional role in heteroduplex repair. Nat Genet 1996; 14:102-5. [PMID: 8782829 DOI: 10.1038/ng0996-102] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Many human tumours have length alterations in repetitive sequence elements. Although this microsatellite instability has been attributed to mutations in four DNA mismatch repair genes in hereditary nonpolyposis colorectal cancer (HNPCC) kindreds, many sporadic tumours exhibit instability but no detectable mutations in these genes. It is therefore of interest to identify other genes that contribute to this instability. In yeast, mutations in several genes, including RTH and MSH3, cause microsatellite instability. Thus, we screened 16 endometrial carcinomas with microsatellite instability for alterations in FEN1 (the human homolog of RTH) and in MSH3 (refs 12-14). Although we found no FEN1 mutations, a frameshift mutation in MSH3 was observed in an endometrial carcinoma and in an endometrial carcinoma cell line. Extracts of the cell line were deficient in repair of DNA substrates containing mismatches or extra nucleotides. Introducing chromosome 5, encoding the MSH3 gene, into the mutant cell line increased the stability of some but not all microsatellites. Extracts of these cells repaired certain substrates containing extra nucleotides, but were deficient in repair of those containing mismatches or other extra nucleotides. A subsequent search revealed a second gene mutation in HHUA cells, a missense mutation in the MSH6 gene. Together the data suggest that the MSH3 gene encodes a product that functions in repair of some but not all pre-mutational intermediates, its mutation in tumours can result in genomic instability and, as in yeast, MSH3 and MSH6 are partially redundant for mismatch repair.
Collapse
Affiliation(s)
- J I Risinger
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
| | | | | | | | | | | |
Collapse
|
50
|
Edelmann W, Cohen PE, Kane M, Lau K, Morrow B, Bennett S, Umar A, Kunkel T, Cattoretti G, Chaganti R, Pollard JW, Kolodner RD, Kucherlapati R. Meiotic pachytene arrest in MLH1-deficient mice. Cell 1996; 85:1125-34. [PMID: 8674118 DOI: 10.1016/s0092-8674(00)81312-4] [Citation(s) in RCA: 398] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Germ line mutations in DNA mismatch repair genes including MLH1 cause hereditary nonpolyposis colon cancer. To understand the role of MLH1 in normal growth and development, we generated mice that have a null mutation of this gene. Mice homozygous for this mutation show a replication error phenotype, and extracts of these cells are deficient in mismatch repair activity. Homozygous mutant males show normal mating behavior but have no detectable mature sperm. Examination of meiosis in these males reveals that the cells enter meiotic prophase and arrest at pachytene. Homozygous mutant females have normal estrous cycles and reproductive and mating behavior but are infertile. The phenotypes of the mlh1 mutant mice are distinct from those deficient in msh2 and pms2. The different phenotypes of the three types of mutant mice suggest that these three genes may have independent functions in mammalian meiosis.
Collapse
Affiliation(s)
- W Edelmann
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|