title: Gene expression signatures for colorectal cancer microsatellite status and HNPCC.
abstract: The majority of microsatellite instable (MSI) colorectal cancers are sporadic, but a subset belongs to the syndrome hereditary non-polyposis colorectal cancer (HNPCC). Microsatellite instability is caused by dysfunction of the mismatch repair (MMR) system that leads to a mutator phenotype, and MSI is correlated to prognosis and response to chemotherapy. Gene expression signatures as predictive markers are being developed for many cancers, and the identification of a signature for MMR deficiency would be of interest both clinically and biologically. To address this issue, we profiled the gene expression of 101 stage II and III colorectal cancers (34 MSI, 67 microsatellite stable (MSS)) using high-density oligonucleotide microarrays. From these data, we constructed a nine-gene signature capable of separating the mismatch repair proficient and deficient tumours. Subsequently, we demonstrated the robustness of the signature by transferring it to a real-time RT-PCR platform. Using this platform, the signature was validated on an independent test set consisting of 47 tumours (10 MSI, 37 MSS), of which 45 were correctly classified. In a second step, we constructed a signature capable of separating MMR-deficient tumours into sporadic MSI and HNPCC cases, and validated this by a mathematical cross-validation approach. The demonstration that this two-step classification approach can identify MSI as well as HNPCC cases merits further gene expression studies to identify prognostic signatures.
authors.affiliation: Molecular Diagnostic Laboratory, Department of Clinical Biochemistry, Aarhus University Hospital, Brendstrupgaardsvej 100, DK-8200, Aarhus, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Kruhøffer
authors.forename: J L
authors.initials: JL
authors.lastname: Jensen
authors.forename: P
authors.initials: P
authors.lastname: Laiho
authors.forename: L
authors.initials: L
authors.lastname: Dyrskjøt
authors.forename: R
authors.initials: R
authors.lastname: Salovaara
authors.forename: D
authors.initials: D
authors.lastname: Arango
authors.forename: K
authors.initials: K
authors.lastname: Birkenkamp-Demtroder
authors.forename: F B
authors.initials: FB
authors.lastname: Sørensen
authors.forename: L L
authors.initials: LL
authors.lastname: Christensen
authors.forename: L
authors.initials: L
authors.lastname: Buhl
authors.forename: J-P
authors.initials: JP
authors.lastname: Mecklin
authors.forename: H
authors.initials: H
authors.lastname: Järvinen
authors.forename: T
authors.initials: T
authors.lastname: Thykjaer
authors.forename: F P
authors.initials: FP
authors.lastname: Wikman
authors.forename: F
authors.initials: F
authors.lastname: Bech-Knudsen
authors.forename: M
authors.initials: M
authors.lastname: Juhola
authors.forename: N N
authors.initials: NN
authors.lastname: Nupponen
authors.forename: S
authors.initials: S
authors.lastname: Laurberg
authors.forename: C L
authors.initials: CL
authors.lastname: Andersen
authors.forename: L A
authors.initials: LA
authors.lastname: Aaltonen
authors.forename: T F
authors.initials: TF
authors.lastname: Ørntoft
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020137:Base Pair Mismatch / Q000235:genetics; D043171:Chromosomal Instability / Q000235:genetics; D003110:Colonic Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D015870:Gene Expression / Q000235:genetics*; D020869:Gene Expression Profiling; D006801:Humans; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011237:Predictive Value of Tests