title: Microsatellite instability in primary and metastatic colorectal cancers.
abstract: Microsatellite instability characterizes a sub-set of sporadic colorectal cancers (CRCs) as well as CRCs from patients with hereditary non-polyposis colorectal cancer (HNPCC). In order to clarify when the cells acquire a replication-error phenotype (RER) during colorectal-tumor progression, we examined the incidence of RER in 80 primary tumors and 36 liver metastases at 8 microsatellite loci; 1 mono-, 5 di-, 1 tetra- and 1 pentanucleotide. RER were detected in 20.1% (17/80) of primary tumors, including 5 tumors showing RER at 2 or more loci (RER2), while the incidence of RER in liver metastases (22.2%, 8/36) was almost the same as that in primary tumors, and there was only one RER2 case in metastases. There were 3 cases in which both primary tumors and liver metastases had the same type of RER at the same locus, and there were 2 cases that showed RER in primary tumors but not in liver metastases. In contrast, there was no case in which RER was detected in a metastasis but not in the corresponding primary tumor. The RER phenotype did not show correlation with any clinicopathological parameters of cancer-cell aggressiveness, such as clinical staging, histological grade and survival. These results indicate that a sub-set of CRCs acquire the RER phenotype in the relatively early stages of colorectal carcinogenesis, and that the RER phenotype is not associated with aggressiveness of CRCs.
authors.affiliation: Division of Biology, National Cancer Center Research Institute, Tokyo, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Ishimaru
authors.forename: J
authors.initials: J
authors.lastname: Adachi
authors.forename: M
authors.initials: M
authors.lastname: Shiseki
authors.forename: N
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: T
authors.initials: T
authors.lastname: Muto
authors.forename: J
authors.initials: J
authors.lastname: Yokota
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004261:DNA Replication; D004276:DNA, Satellite / Q000737:chemistry*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000556:secondary; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype
chemical_list: D004276:DNA, Satellite