- Email: [email protected]
It's a knockout!
UPDATE
TARGETS Vol. 2, No. 3 June 2003
CONFERENCE New insights into carcinogenesis Chromosomal breakages and rearrangements lie at the heart of many leukaemias, lymphomas and sarcomas. For example, CML is caused by a chromosomal translocation that fuses the ABL gene on chromosome 9 to the BCR gene on chromosome 22.As a result, the kinase activity of ABL is greatly enhanced. It is therefore not surprising that yet another fusion protein is involved in the pathogenesis of HES.What is new is the discovery of a gain-of-function fusion protein that results from a chromosomal deletion. In the past, scientists have missed such gain-of-function deletions because they can
not be detected with standard cytogenetic tools.‘This study tells us is that we have to look more carefully,’ concludes Druker. ‘Just because there is no observable chromosomal abnormality, that does not mean that rearrangements could not have occurred.We have to continue to consider that possibility.’ According to Gilliland, the same mechanism could be at work in the four HES patients who responded to Gleevec but who do not harbour the FIP1L1/PDGF-α protein.‘We have a very focused screen looking at the other tyrosine kinases that are known to be targets of Gleevec to see whether this deletional mechanism applies here,’ he says.
Gilliland is also thinking of developing a high-throughput genomic screen to find similar deletions in other tumours. After all,‘this may be a widespread mechanism for carcinogenesis in other types of cancers.’
References 1 Heinrich MC et al. (2003) PDGFRA activating mutations in gastrointestinal stromal tumors. Science 299, 708–710 2 Gleich GJ et al. (2002) Treatment of hypereosinophilic syndrome with imatinib mesilate. Lancet 359, 1577–1578 3 Cools J et al. (2003) A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome. N. Engl. J. Med. 348, 1201–1214
It’s a knockout! Julie P. Howard, Research Manager (Translational Research), Cancer Research UK, Kingsway, London, UK; e-mail: [email protected]
The SMi Target Validation conference, held in London on 7–8 April 2003, saw delegates from across the globe address the issues facing the future of target validation.The meeting took the format of several presentations given by respected individuals representing a large number of biotechnology and pharmaceutical companies.
Target validation Target validation is one of the most rapidly developing areas of drug research at the present time.The speakers addressed numerous issues including new technologies for identifying potential targets, recent developments in the field of target validation and the use of the knockout (KO) mouse as a disease model. One of the major issues surrounding the future of target validation is how to maximize the potential already available by current means.Target validation is generally grouped into two sections: cellular, including mRNA and protein studies,
76
www.drugdiscoverytoday.com
and system-based disease models, such as knockout mice.The most recent major advances are short interfering RNA (siRNA) studies and high throughput mouse KO models, thus, this report will focus on a few of the presentations given on these areas.
Knockout mouse disease models A large proportion of the presentations given focussed on KO mouse disease models.The completion of the human genome project has revealed a vast number of potential drug targets, thus offering a wealth of opportunity for drug therapeutics. The assessment of these targets as potential druggable sites is one of the major challenges that lie ahead. High throughput screens involving knockouts to identify targets will enable a genome wide view of prospective targets for drug discovery. Kate Holt of Lexicon Genetics (http://www.lexgen.com) presented recent work involving a retrospective study of KO phenotypes, which target the current top
100 drugs available on the market today, to effectively enable them to mine the druggable genome using a large scale mouse KO system. Of the top 100 drugs screened, studies revealed that these drugs are mainly directed at 43 targets, 34 of these currently have KO models produced. Holt reported that they have currently analyzed 750 targets of the full 5000 druggable genome and estimate that 100–150 potential targets will be identified once the full 5000 genes have been analyzed. Michael Schoor of Artemis further discussed the advantages of KO models. Knockouts can produce rapid high quality in vivo gene function analysis, leading to a focus on specific targets and thus a reduced attrition rate and increased research efficiency. Artemis have produced ArteMice CONDITIONAL™ and ArteMice SPEED™ systems, which produce the deletion of the target gene in all tissues and with a sustainable effect and a threefold faster production of KOs, reduced from
1477-3627/03/$ – see front matter ©2003 Elsevier Science Ltd. All rights reserved. PII: S1477-3627(03)02323-7
UPDATE
TARGETS Vol. 2, No. 3 June 2003
CONFERENCE 18–24 months to 6–8 months.The SPEED™ technique involves the use of designer embryonic stem (ES) cells carrying the disease gene and taking tetraploid blastocytes to create a 100% homozygous conditional KO mouse on a disease background.Artemis have developed 34 F1 ES designer lines ready for use in a range of disease models, including cancer and gastrointestinal (GI) disease models.These mouse models are able to overcome such problems as embryonic lethality and also enable the study of gene function in adults in a disease background.
High information content screening The second day of the conference saw presentations of a different aspect. Johan Geysen of Union Biometrica (http://www.unionbio.com) presented their latest development in instrumentation for use in high information content screening. The system consists of MIAS2, a microscopic reader with an unprecedented combination of flexibility, sensitivity and speed. MIAS2 has been designed to cope with the expanding
need for high throughput screens with the aim of streamlining the target validation process and is suitable for use with cellbased assays, tissue sections, bead assays and small-animal model organisms.This technology is teamed with COPAS, a large particle flow sorter, which is required for automatically sorting the isolation of different stages of life and is vastly more sophisticated than manual methods resulting in extremely pure populations. COPAS also has the ability to sort viable from dead organisms and as a result of recent advances into high throughput screens involving bead based assays, has been developed to sort beads according to quality and those with fluorescent tags. Geysen reported that future plans for the COPAS system included customizing the technique to enable sorting of individual organs within a species and the development of partnerships within industry to maximize ‘speciality technology’ for high content screening in genomics and drug discovery. Robert Coleman of Pharmagene Laboratories (http://www.pharmagene.com) introduced their recent work on
Pharmagene TargetEvaluator™, a comprehensive human-gene-expression database containing information on the expression of gene transcripts in human tissues. It is based on a combination of human tissue for the purposes of expression profiling and works by enabling the selection and stratification of genes of interest.The database is regularly updated and subscribers benefit from a continuously expanding collection of gene expression profiles with the ability to influence the content of their updates to enable more relevant targets to be included.
Targeting the future The conference gave an overview of a range of the latest technologies available as tools for the rapidly expanding field of target validation.The presentations highlighted new and exciting challenges that pave the road ahead; in particular, the need for high throughput methods to cope with the vast number of targets revealed on completion of the human genome project and the value of the advancements in technologies for assaying data on a large scale.
Contributions to TARGETS TARGETS reviews advances in genomics and proteomics that will impact on drug and target discovery. Coverage includes new drug targets in a therapeutic area; new classes of target; new and emerging technologies; new applications of existing technologies; and updates on the progress of gene sequencing projects and the Human Proteome Project. Authors should aim for topicality rather than comprehensive coverage. Ultimately, articles should improve the reader’s understanding of the field addressed, and enable them to keep abreast of the latest advances and trends. Please note that publication of Review articles is subject to satisfactory expert peer and editorial review.The publication of Update and Editorial articles is subject to satisfactory editorial review. In addition, personal perspectives published in TARGETS do not represent the view of the journal or its editorial staff If you would like to contribute to the Reviews, Update and Editorial sections of TARGETS in the future, please submit your proposals to: Dr Joanna Owens, Editor (e-mail:[email protected]).
www.drugdiscoverytoday.com
77
TARGETS Vol. 2, No. 3 June 2003
CONFERENCE New insights into carcinogenesis Chromosomal breakages and rearrangements lie at the heart of many leukaemias, lymphomas and sarcomas. For example, CML is caused by a chromosomal translocation that fuses the ABL gene on chromosome 9 to the BCR gene on chromosome 22.As a result, the kinase activity of ABL is greatly enhanced. It is therefore not surprising that yet another fusion protein is involved in the pathogenesis of HES.What is new is the discovery of a gain-of-function fusion protein that results from a chromosomal deletion. In the past, scientists have missed such gain-of-function deletions because they can
not be detected with standard cytogenetic tools.‘This study tells us is that we have to look more carefully,’ concludes Druker. ‘Just because there is no observable chromosomal abnormality, that does not mean that rearrangements could not have occurred.We have to continue to consider that possibility.’ According to Gilliland, the same mechanism could be at work in the four HES patients who responded to Gleevec but who do not harbour the FIP1L1/PDGF-α protein.‘We have a very focused screen looking at the other tyrosine kinases that are known to be targets of Gleevec to see whether this deletional mechanism applies here,’ he says.
Gilliland is also thinking of developing a high-throughput genomic screen to find similar deletions in other tumours. After all,‘this may be a widespread mechanism for carcinogenesis in other types of cancers.’
References 1 Heinrich MC et al. (2003) PDGFRA activating mutations in gastrointestinal stromal tumors. Science 299, 708–710 2 Gleich GJ et al. (2002) Treatment of hypereosinophilic syndrome with imatinib mesilate. Lancet 359, 1577–1578 3 Cools J et al. (2003) A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome. N. Engl. J. Med. 348, 1201–1214
It’s a knockout! Julie P. Howard, Research Manager (Translational Research), Cancer Research UK, Kingsway, London, UK; e-mail: [email protected]
The SMi Target Validation conference, held in London on 7–8 April 2003, saw delegates from across the globe address the issues facing the future of target validation.The meeting took the format of several presentations given by respected individuals representing a large number of biotechnology and pharmaceutical companies.
Target validation Target validation is one of the most rapidly developing areas of drug research at the present time.The speakers addressed numerous issues including new technologies for identifying potential targets, recent developments in the field of target validation and the use of the knockout (KO) mouse as a disease model. One of the major issues surrounding the future of target validation is how to maximize the potential already available by current means.Target validation is generally grouped into two sections: cellular, including mRNA and protein studies,
76
www.drugdiscoverytoday.com
and system-based disease models, such as knockout mice.The most recent major advances are short interfering RNA (siRNA) studies and high throughput mouse KO models, thus, this report will focus on a few of the presentations given on these areas.
Knockout mouse disease models A large proportion of the presentations given focussed on KO mouse disease models.The completion of the human genome project has revealed a vast number of potential drug targets, thus offering a wealth of opportunity for drug therapeutics. The assessment of these targets as potential druggable sites is one of the major challenges that lie ahead. High throughput screens involving knockouts to identify targets will enable a genome wide view of prospective targets for drug discovery. Kate Holt of Lexicon Genetics (http://www.lexgen.com) presented recent work involving a retrospective study of KO phenotypes, which target the current top
100 drugs available on the market today, to effectively enable them to mine the druggable genome using a large scale mouse KO system. Of the top 100 drugs screened, studies revealed that these drugs are mainly directed at 43 targets, 34 of these currently have KO models produced. Holt reported that they have currently analyzed 750 targets of the full 5000 druggable genome and estimate that 100–150 potential targets will be identified once the full 5000 genes have been analyzed. Michael Schoor of Artemis further discussed the advantages of KO models. Knockouts can produce rapid high quality in vivo gene function analysis, leading to a focus on specific targets and thus a reduced attrition rate and increased research efficiency. Artemis have produced ArteMice CONDITIONAL™ and ArteMice SPEED™ systems, which produce the deletion of the target gene in all tissues and with a sustainable effect and a threefold faster production of KOs, reduced from
1477-3627/03/$ – see front matter ©2003 Elsevier Science Ltd. All rights reserved. PII: S1477-3627(03)02323-7
UPDATE
TARGETS Vol. 2, No. 3 June 2003
CONFERENCE 18–24 months to 6–8 months.The SPEED™ technique involves the use of designer embryonic stem (ES) cells carrying the disease gene and taking tetraploid blastocytes to create a 100% homozygous conditional KO mouse on a disease background.Artemis have developed 34 F1 ES designer lines ready for use in a range of disease models, including cancer and gastrointestinal (GI) disease models.These mouse models are able to overcome such problems as embryonic lethality and also enable the study of gene function in adults in a disease background.
High information content screening The second day of the conference saw presentations of a different aspect. Johan Geysen of Union Biometrica (http://www.unionbio.com) presented their latest development in instrumentation for use in high information content screening. The system consists of MIAS2, a microscopic reader with an unprecedented combination of flexibility, sensitivity and speed. MIAS2 has been designed to cope with the expanding
need for high throughput screens with the aim of streamlining the target validation process and is suitable for use with cellbased assays, tissue sections, bead assays and small-animal model organisms.This technology is teamed with COPAS, a large particle flow sorter, which is required for automatically sorting the isolation of different stages of life and is vastly more sophisticated than manual methods resulting in extremely pure populations. COPAS also has the ability to sort viable from dead organisms and as a result of recent advances into high throughput screens involving bead based assays, has been developed to sort beads according to quality and those with fluorescent tags. Geysen reported that future plans for the COPAS system included customizing the technique to enable sorting of individual organs within a species and the development of partnerships within industry to maximize ‘speciality technology’ for high content screening in genomics and drug discovery. Robert Coleman of Pharmagene Laboratories (http://www.pharmagene.com) introduced their recent work on
Pharmagene TargetEvaluator™, a comprehensive human-gene-expression database containing information on the expression of gene transcripts in human tissues. It is based on a combination of human tissue for the purposes of expression profiling and works by enabling the selection and stratification of genes of interest.The database is regularly updated and subscribers benefit from a continuously expanding collection of gene expression profiles with the ability to influence the content of their updates to enable more relevant targets to be included.
Targeting the future The conference gave an overview of a range of the latest technologies available as tools for the rapidly expanding field of target validation.The presentations highlighted new and exciting challenges that pave the road ahead; in particular, the need for high throughput methods to cope with the vast number of targets revealed on completion of the human genome project and the value of the advancements in technologies for assaying data on a large scale.
Contributions to TARGETS TARGETS reviews advances in genomics and proteomics that will impact on drug and target discovery. Coverage includes new drug targets in a therapeutic area; new classes of target; new and emerging technologies; new applications of existing technologies; and updates on the progress of gene sequencing projects and the Human Proteome Project. Authors should aim for topicality rather than comprehensive coverage. Ultimately, articles should improve the reader’s understanding of the field addressed, and enable them to keep abreast of the latest advances and trends. Please note that publication of Review articles is subject to satisfactory expert peer and editorial review.The publication of Update and Editorial articles is subject to satisfactory editorial review. In addition, personal perspectives published in TARGETS do not represent the view of the journal or its editorial staff If you would like to contribute to the Reviews, Update and Editorial sections of TARGETS in the future, please submit your proposals to: Dr Joanna Owens, Editor (e-mail:[email protected]).
www.drugdiscoverytoday.com
77