title: [Expression of circadian gene NPAS2 in colorectal cancer and its prognostic significance].
abstract: OBJECTIVE
  To study the expression of NPAS2 in colorectal cancer (CRC) and analyze its relationship with the clinicopathological parameters and prognosis of the patients.
  
  
  METHODS
  Real-time q-PCR was used to detect the expression of NPAS2 mRNA in 40 fresh CRC tissues and paired adjacent tissues; immunohistochemistry was used to detect the expression of NPAS2 protein in 120 paraffin-embedded tumor and adjacent tissues. The relationship between NPAS2 expression level and the 5-year survival rate of 78 CRC patients with follow-up data were analyzed with Kaplan-Meier survival analysis.
  
  
  RESULTS
  Compared with the adjacent tissues, fresh CRC tissue expressed significantly lower NPAS2 mRNA levels (P<0.01). Among the paraffin-embedded CRC tissues, 19.2% were positive for NPAS2 expression, as compared to a much higher rate of 62.5% in the adjacent tissues (P<0.05). The expression of NPAS2 was correlated with the tumor size, lymph node metastasis and TNM stages (P<0.05) but not with the patients' gender, age, distant tumor metastasis, differentiation, or invasion. Patients with high NPAS2 expression levels had a significantly higher 5-year survival rate than those with low NPAS2 expressions (P=0.0001).
  
  
  CONCLUSIONS
  NPAS2 is down-regulated in CRC and closely correlated with the malignant biological behavior of the tumor and 5-year survival of the patients, suggesting its value in predicting the prognosis of the CRC patients.
authors.affiliation: Depatment of Pathology, Vocational College of Health, Guangzhou Medical University, Guangzhou 510925, China.E-mail: 470383079@ qq.com.
authors.forename: Shao-Fen
authors.initials: SF
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.forename: Hai-Yun
authors.initials: HY
authors.lastname: Yang
authors.forename: Pei-Qin
authors.initials: PQ
authors.lastname: Li
authors.forename: Xiu-Fang
authors.initials: XF
authors.lastname: Chi
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D015536:Down-Regulation; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011379:Prognosis; D012333:RNA, Messenger; D060888:Real-Time Polymerase Chain Reaction; D015996:Survival Rate
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C104264:NPAS2 protein, human