title: [Downregulation of chromobox protein homolog 7 expression in multiple human cancer tissues].
abstract: OBJECTIVE
  To investigate the relationship between chromobox protein homolog 7 (cbx7) expression and the occurrence and development of colorectal carcinoma (CRC), gastric carcinoma (GC) and hepatocarcinoma (HCC) tissues.
  
  
  METHODS
  The samples of neoplastic tissues and the corresponding cutting-edge normal tissues from 22 cases of CRC, 20 cases of GC, 30 cases of HCC were surgically collected. Level of cbx7 mRNA was detected with a fluorescent quantitative RT-PCR assay, and the correlationship among expression of cbx7 mRNA, the patients' clinicopathologic features and the surviving time after surgery was analyzed.
  
  
  RESULTS
  The relative copy number of cbx7 mRNA in carcinomas and the normal tissues was 0.010 ± 0.015 vs 0.053 ± 0.042 for CRCs, 0.197 ± 0.195 vs 1.891 ± 1.254 for GCs, and 0.008 ± 0.008 vs 0.030 ± 0.021 for HCCs, respectively. Compared with the corresponding normal tissues, cbx7 expression was significantly downregulated in CRCs, GCs, and HCCs (t = -7.351, -5.417 and -6.680, respectively, P < 0.01). The expression of cbx7 mRNA in CRCs had significant differences not only between two age groups (the relative copy number of cbx7 mRNA in age > 55 group was 0.007 ± 0.015, but 0.017 ± 0.012 in age ≤ 55 group, t = -2.586, P = 0.022); but also between vascular embolus-positive and negative groups (the level of cbx7 mRNA in positive and negative group was 0.022 ± 0.021 vs 0.006 ± 0.011, t = -3.175, P = 0.010). The area under the receiver operating characteristics (ROC) curve is 0.769 (P = 0.033). when the Cut-off value of the relative copy number of cbx7 mRNA was 0.002 in CRCs. The values less-than 0.002 were defined as low expression. The CRC patients with low expression of cbx7 had a shorter overall survival time; whose 5 years survival rate was only 30.8% (4/13); while the rate was 77.8% (7/9) in high expression of cbx7 group. The difference had statistical significance (χ(2) = 4.329, P = 0.037). The similar differences could not be found among GC and HCC patients.
  
  
  CONCLUSIONS
  Downregulation of cbx7 expression was very common among multiple carcinomas cases, and the downregulation influenced the prognosis of CRC patients.
authors: Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing 100142, China.
authors: Zhen-Po
authors: ZP
authors: Guan
authors: Lian-Kun
authors: LK
authors: Gu
authors: Bao-Cai
authors: BC
authors: Xing
authors: Jia-Fu
authors: JF
authors: Ji
authors: Jin
authors: J
authors: Gu
authors: Da-Jun
authors: DJ
authors: Deng
mesh_terms: D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms; D063150:Polycomb Repressive Complex 1; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism*
chemical_list: C503627:CBX7 protein, human; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1