title: Assessment of chromosomal imbalances in CIMP-high and CIMP-low/CIMP-0 colorectal cancers.
abstract: Data presented in a number of recent studies have revealed a negative correlation between CpG island methylator phenotype (CIMP) and chromosomal instability (CIN) measured by a loss of heterozygosity (LOH) of selected loci, suggesting that CIN and CIMP represent two independent mechanisms in sporadic colorectal cancer (CRC) carcinogenesis. However, CIN is a heterogeneous phenomenon, which may be studied not only by employing LOH analysis but also by observing chromosomal imbalances (gains and deletions). The current study aimed to investigate the relationship between CIMP and chromosomal gains and deletions (assessed by comparative genomic hybridization) in a group of 20 CIMP-high and 79 CIMP-low/CIMP-0 CRCs. Our results revealed that the mean numbers of gains and of total chromosomal imbalances were significantly greater (p = 0.004 and p = 0.007, respectively) in the CIMP-low/CIMP-0 group compared to the CIMP-high group, while no significant difference was observed between the mean numbers of losses (p = 0.056). The analysis of copy number changes of 41 cancer-related genes by multiplex ligation-dependent probe amplification showed that CRK gene was exclusively deleted in CIMP-low/CIMP-0 tumors (p = 0.02). Given that chromosomal losses play an important role in tumor suppressor inactivation and chromosomal gains, in the activation of proto-oncogenes, we hypothesize that tumor suppressor inactivation plays similar roles in both CIMP-high and CIMP-low/CIMP-0 CRCs, while the predominance of chromosomal gains in CIMP-low/CIMP-0 tumors may suggest that the activation of proto-oncogenes is the underlying mechanism of CIMP-low/CIMP-0 CRC progression.
authors.affiliation: Department of Genetics, Wroclaw Medical University, ul. Marcinkowskiego 1, 50-368 Wroclaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kozlowska
authors.forename: Pawel
authors.initials: P
authors.lastname: Karpinski
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Szmida
authors.forename: Izabela
authors.initials: I
authors.lastname: Laczmanska
authors.forename: Blazej
authors.initials: B
authors.lastname: Misiak
authors.forename: David
authors.initials: D
authors.lastname: Ramsey
authors.forename: Marek
authors.initials: M
authors.lastname: Bebenek
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kielan
authors.forename: Karolina A
authors.initials: KA
authors.lastname: Pesz
authors.forename: Maria M
authors.initials: MM
authors.lastname: Sasiadek
mesh_terms: D000328:Adult; D000368:Aged; D002869:Chromosome Aberrations; D015179:Colorectal Neoplasms / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D018899:CpG Islands / Q000235:genetics*; D056915:DNA Copy Number Variations; D019175:DNA Methylation; D005260:Female; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D050737:Proto-Oncogene Proteins c-crk / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D018631:ras Proteins / Q000235:genetics
chemical_list: C485285:CRK protein, human; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D016159:Tumor Suppressor Protein p53; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins