title: Metastatic susceptibility locus, an 8p hot-spot for tumour progression disrupted in colorectal liver metastases: 13 candidate genes examined at the DNA, mRNA and protein level.
abstract: BACKGROUND
  Mortality from colorectal cancer is mainly due to metastatic liver disease. Improved understanding of the molecular events underlying metastasis is crucial for the development of new methods for early detection and treatment of colorectal cancer. Loss of chromosome 8p is frequently seen in colorectal cancer and implicated in later stage disease and metastasis, although a single metastasis suppressor gene has yet to be identified. We therefore examined 8p for genes involved in colorectal cancer progression.
  
  
  METHODS
  Loss of heterozygosity analyses were used to map genetic loss in colorectal liver metastases. Candidate genes in the region of loss were investigated in clinical samples from 44 patients, including 6 with matched colon normal, colon tumour and liver metastasis. We investigated gene disruption at the level of DNA, mRNA and protein using a combination of mutation, semi-quantitative real-time PCR, western blotting and immunohistochemical analyses.
  
  
  RESULTS
  We mapped a 2 Mb region of 8p21-22 with loss of heterozygosity in 73% of samples; 8/11 liver metastasis samples had loss which was not present in the corresponding matched primary colon tumour. 13 candidate genes were identified for further analysis. Both up and down-regulation of 8p21-22 gene expression was associated with metastasis. ADAMDEC1 mRNA and protein expression decreased during both tumourigenesis and tumour progression. Increased STC1 and LOXL2 mRNA expression occurred during tumourigenesis. Liver metastases with low DcR1/TNFRSF10C mRNA expression were more likely to present with extrahepatic metastases (p = 0.005). A novel germline truncating mutation of DR5/TNFRSF10B was identified, and DR4/TNFRSF10A SNP rs4872077 was associated with the development of liver metastases (p = 0.02).
  
  
  CONCLUSIONS
  Our data confirm that genes on 8p21-22 are dysregulated during colorectal cancer progression. Interestingly, however, instead of harbouring a single candidate colorectal metastasis suppressor 8p21-22 appears to be a hot-spot for tumour progression, encoding at least 13 genes with a putative role in carcinoma development. Thus, we propose that this region of 8p comprises a metastatic susceptibility locus involved in tumour progression whose disruption increases metastatic potential.
authors.affiliation: 1Wakefield Gastroenterology Research Institute, Wellington, New Zealand. Donia.Macartney@esr.cri.nz
authors.forename: Donia P
authors.initials: DP
authors.lastname: Macartney-Coxson
authors.forename: Kylie A
authors.initials: KA
authors.lastname: Hood
authors.forename: Hong-jun
authors.initials: HJ
authors.lastname: Shi
authors.forename: Teresa
authors.initials: T
authors.lastname: Ward
authors.forename: Anna
authors.initials: A
authors.lastname: Wiles
authors.forename: Rosemary
authors.initials: R
authors.lastname: O'Connor
authors.forename: David A
authors.initials: DA
authors.lastname: Hall
authors.forename: Rod A
authors.initials: RA
authors.lastname: Lea
authors.forename: Janice A
authors.initials: JA
authors.lastname: Royds
authors.forename: Richard S
authors.initials: RS
authors.lastname: Stubbs
authors.forename: Serena
authors.initials: S
authors.lastname: Rooker
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000556:secondary*; D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002872:Chromosome Deletion; D002898:Chromosomes, Human, Pair 8; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D004247:DNA / Q000032:analysis; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000556:secondary*; D009362:Neoplasm Metastasis / Q000235:genetics*; D011110:Polymorphism, Genetic; D012333:RNA, Messenger / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; C051795:teleocalcin; D004247:DNA; D000594:Amino Acid Oxidoreductases; C119091:LOXL2 protein, human