Ciphergen Biosystems, Inc. (Palo Alto, CA, USA)has launched an advanced ProteinChip™ arraysystem (see Box 1). This system selectively capturestrace amounts of proteins directly from bodily fluidsor tissue specimens by using SELDI (surfaceenhanced laser desorption/ionisation) technology toprofile captured proteins (Fig. 1).

The first-generation system has been available fortwo years and has already generated some excitingresults. Brian Austen’s group at St George’s Hospital(London, UK) received one of the first systems. In1998, Huw Davies (Ciphergen Biosystems Ltd.,Camberley, UK), one of the company’s field scientists,ran a week-long demonstration using samples fromAusten’s lab. ‘In the limited time available, BrianAusten’s group developed an assay to detect nanomolaramounts of amyloid b (Ab) protein, the protein thoughtto be at the root of the brain changes in Alzheimer’sdisease’, explains Davies.

The ProteinChip system was used to identify themolecular weights of various truncated amyloidpeptides captured on a single type of antibody surfaceand gave a quantitative assessment of the proportions ofAb40 and Ab42 present1. ‘This system could be veryuseful for looking at the cellular processingmechanisms of amyloid precursor protein (APP). Itshould aid us in our efforts to identify biomarkers thatcould form the basis for a presymptomatic assay forAlzheimer’s disease. It could also be used to developinhibitors of g-1–42 secretase and so has therapeuticpotential’, comments Austen.

Enrique Dalmasso, senior research scientist atCiphergen, emphasizes that the technology has broadapplications and will have far-reaching implications formany areas of medical research. ‘The use ofProteinChip systems will speed up the discovery ofnovel disease biomarkers and the development ofspecific marker assays’, he predicts. Previously,developing an assay for a particular disease markerprotein took months to years and was labour intensive.Initial discovery required many specialized techniques,such as two-dimensional gel electrophoresis,proteolytic digestion and mass spectrometry. Antibodyproduction followed by ELISA (enzyme-linkedimmunoabsorbent assay) development were the norm,particularly for marker validation. ‘The SELDIProteinChip technology uses the same rapid assayplatform for both marker discovery and validation.Simultaneous monitoring of multiple marker proteinsprovides a ‘phenomic fingerprint’ – a more reliableindicator of disease stages than any single marker’, saysDalmasso. In a test carried out last year, Ciphergenscientists used the ProteinChip system to investigateserum samples from healthy individuals and patientswith different stages of cancer. In only three days, theyfound six potential markers for prostate cancer. ‘Usingstandard techniques, discovery and validation of the

same number of potential markers may take months toyears and has yet to be demonstrated’, adds Dalmasso.

Before potential biomarkers can be used clinically,they must be validated by comparing their expressionin large numbers of patients. It is also important to findenough markers to provide a reliable ‘phenomicfingerprint’ for a specific disease. According toDalmasso, this process is already well under way withprostate and ovarian cancer. He reports that LanceLiotta (Food and Drug Administration, Bethesda, MD,USA) and Chip Petricoin (National Cancer Institute,Bethesda, MD, USA) have combined Ciphergen’sProteinChip system with the technique of laser capturemicrodissection (LCM) to identify, and partly validate,several markers for prostate cancer. At the end of April,the group announced their preliminary results at the90th Annual Meeting of the American Association forCancer Research in Philadelphia2. Tissue obtained frompatients was microdissected by firing a laser at a thin

section backed by thermoplastic film. Guided by thisreal-time microscopy system, the researchers were ableto target individual cells (normal, pre-cancerous andcancerous) for separate capture on the film. The cellswere lysed directly and the resulting material was thentransferred onto a SELDI ProteinChip array. Thesubsequent analysis of 500–1000 cells of differenttypes produced several ‘phenomic fingerprints’ thatrevealed well-defined patterns of protein expression.The group also showed that the protein fingerprintchanges markedly as a normal epithelial cell progressesto a pre-invasive carcinoma cell and then to an invasivecancerous cell.

Ciphergen’s ProteinChip technology in combinationwith LCM has also been used by Monica Brown(National Cancer Institute, Bethesda, MA, USA) in herefforts to identify biomarkers for ovarian cancer. At the7th Biennial International Forum on ovarian cancer,Brown described how her team has recently expanded

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Figure 1. Surface enhanced laser desorption/ionization (SELDI)-based ProteinChipª technology. (a) Patientsample of proteins is processed on ProteinChip array. (b) Sample proteins bind to chemical ÔhooksÕ or bio-logical Ôdocking sitesÕ on ProteinChip array surface. Protein of interest appears in red. (c) Rinsing away con-taminants and buffers eliminates sample ÔnoiseÕ. (d) Laser ionizes retained proteins to detect mass (mol-ecular weight). (e) Software produces ÔmapÕ of proteins, revealing expression of marker protein (red) inpatient sample compared to control sample.

Fingerprinting disease with protein chip arrays

their evaluation of ovarian neoplasms to include thedevelopment of protein fingerprints from LCM-derivedovarian tissues using the ProteinChip system; 200LCM-derived epithelial ovarian cancer cells wereselected for study from three moderately differentiatedpapillary serous ovarian tumours. A SELDIhydrophobic ProteinChip array was used for theanalysis, which found a ‘phenomic fingerprint’ withfive to eight unique peptides of different molecularweights shared by all three ovarian tumours.

‘The major impact of the ProteinChip system willbe significant advances in the ease and accuracy ofearly diagnosis’, says Dalmasso. ‘This will be clinicallyuseful for many diseases. As well as enabling veryearly diagnosis, it will also make it possible to monitordisease progression and the effectiveness of treatmentmuch more effectively.’Taking ovarian cancer as anexample, symptoms of ovarian cancer appear onlywhen the cancer is well established and has probablymetastasized. A diagnostic test developed with theProteinChip system should enable the ovarian cancer tobe diagnosed much earlier, perhaps a year beforesymptoms develop, enabling physicians to carry outsurgery and begin chemotherapeutic treatment in timefor it to have a good chance of success. ‘Early andaccurate diagnosis are our ultimate goals for the systembecause they will mean improved life expectancy andquality of life for countless individuals’, concludesDalmasso.

1 Austen, B. et al.(1999) The role of cholesterol in thebiosynthesis of b-amyloid, NeuroReport10,1699–1705

2 Paweletz, C.P. et al.(1999) A novel, proteomicapproach to monitor carcinogenic disease progressionusing surface enhanced desorption ionizationspectroscopy (SELDI) of laser capture microdissection(LCM)-derived cells from cancer tissue, Proc. Amer.Assoc. Cancer Res. 40, 411

Kathryn SeniorFreelance science writer

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Box 1. The ProteinChipªsystem in action

Proteins are captured on the surface of ProteinChipArrays – small plates that contain spots up to 1 mm indiameter. Each surface is prepared with a coating rel-evant to the protein or set of proteins under study.This coating can comprise biological molecules, suchas an antibody specific for the molecule being studied,or it can be pre-coated with a range of broadly selec-tive chromatographic surfaces that capture proteinsthrough their chemical properties (such as charge in-teraction, hydrophobic interaction and immobilizedmetal affinity capture). The coated surfaces are ex-posed to a sample and, after a procedure of repeatedwashing to remove buffers and contaminants, theProteinChip reader is used to profile the captured pro-teins and determine their accurate molecular weights.

For the first time, the Howard Hughes MedicalInstitute (HHMI; Chevy Chase, MD, USA) isorganizing an international competition forresearchers in the field of infectious diseases andparasitology. Usually, grants are awarded tospecific geographical regions rather than toresearchers in specific disease areas. In total,US$14 million will be awarded to about 40researchers outside the USA.

The grants are aimed at researchers who usemolecular genetics and immunology tocharacterize pathogenic microorganisms,particularly those affecting Third World countries.‘We think this effort will speed the development ofimproved approaches for combating diseases suchas malaria, Chagas’ disease, diarrhoeal diseases,and others that claim a huge toll around the world,particularly in developing countries’, says DavidJarmul, Deputy Director of Communications,HHMI. ‘We think there’s a great opportunity toapply the tools of molecular and cellular biologyto learn more about these diseases and devise newways of overcoming them.’

Jarmul believes that this funding effort couldhelp combat infectious diseases in several ways.‘Expanding our knowledge about infectious andparasitic diseases could lead to improveddiagnostics, vaccines, drugs and clinicaltreatments’, he explains.

The HHMI has been supporting medicalresearch since it was set up in 1954. Although themain aim of the institute is to support research inthe USA, it has awarded US$53 million inoverseas grants since 1991.

The deadline for applications is 15th September1999, but the competition is available only toscientists nominated by other experts in the fieldand other research organizations. If you hold afull-time appointment at a university or other non-profit-making organization, have publishedEnglish language papers in international, peer-reviewed journals, and would like moreinformation on the competition, go tohttp://www.hhmi.org/grants/international.

Sharon DorrellFreelance science writer

International grants for infectious diseaseresearch

Rapid updateUK government boosts numbers of medical training placesOver 840 new places are to be created forundergraduate medical students in the UK overthe next two years. The places are being allocatedto existing medical schools but new medicalschools might also be created in the future: theUniversity of East Anglia and, jointly, theUniversities of Exeter and Plymouth have beeninvited to develop full business plans for thecreation of two new medical schools. A proposalfrom King’s College London and the Universityof Kent to widen access to medical education isalso being considered.

Britain says ‘no’ to human cloning researchThe UK Government has reaffirmed its policythat human reproductive cloning is ethicallyunacceptable, and has announced a ban onresearch into the use of human cloning fortherapeutic purposes until there is more evidenceof its benefit to humankind. On 24 June, TessaJowell, the Minister for Public Health, announced

plans to set up an independent expert advisorygroup to investigate the potential benefits andrisks of therapeutic research in this area.

NIH Director calls for review of US gene therapy vector labsDuring his Keynote Address at the AmericanSociety of Gene Therapy (ASGT) Second AnnualSymposium (Washington DC, 12 June), NIHDirector Harold Varmus explained that he iscurrently considering a comprehensiveevaluation of the NIH National Gene VectorLaboratories, having received a deluge of lettersexpressing concerns about them. The labs supplyclinical-grade vectors for use in human gene-therapy trials. Varmus also warned that he mightrestore a ‘double approval’ process, in which boththe US Food and Drug Administration and theRecombinant DNA Advisory Committee (RAC)must approve any new gene therapy protocol, ifresearchers continue to ignore the RAC’s role inconsidering the scientific, ethical and societalissues surrounding new gene therapies.

Catherine BrooksbankMolecular Medicine Today