title: [Preliminary study on relationship between multi-drug resistance-associated protein 4 and radiosensitivity of rectal cancer].
abstract: OBJECTIVE
  To explore the correlation between multi-drug resistance-associated protein 4(MRP4) and the sensitivity of rectal cancer to radiation.
  
  
  METHODS
  A total of 95 patients with advanced rectal cancer and received radiation therapy between January 2000 and January 2009. MRP4 and P53 protein expression in the paraffin-embedded specimen were detected by immunohistochemistry. Logistic regression analysis was used to evaluate factors associated with the sensitivity of rectal cancer to radiation.
  
  
  RESULTS
  Forty patients(42%) were sensitive to radiation therapy, of whom 10(11%) achieved pathological complete remission. Fifty-five patients were (58%) not responsive to radiation. Patients with low expression of MRP4 had a 66.7%(24/36) response rate, significantly higher than that of patients with high MRP4 expression (29.1%,16/59)(P<0.05). Patients with low expression of P53 had a 63.9%(23/36) response rate, significantly higher than that of patients with high P53 expression(28.8%,17/59)(P<0.01). The response rate after long course radiation therapy was 83.3%(20/24), significantly higher than that of patients who underwent short and medium course radiation[(31.3%, 5/16) and(27.3%,15/55)](P<0.01). Multivariate Logistic regression analysis showed radiation regimen, the expression of P53 and MRP4 protein were independently associated with the sensitivity of rectal cancer to radiation(P<0.05).
  
  
  CONCLUSIONS
  MRP4 may serve as a predictive marker for the sensitivity of rectal cancer to preoperative radiation.
authors.affiliation: Department of Colorectal Surgery, Changhai Hospital, The Second Military Medical University, Shanghai 200433, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Chai
authors.forename: Zhi-qi
authors.initials: ZQ
authors.lastname: Yu
authors.forename: Chuan-gang
authors.initials: CG
authors.lastname: Fu
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Lian-jie
authors.initials: LJ
authors.lastname: Liu
authors.forename: Chang
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D009367:Neoplasm Staging; D011836:Radiation Tolerance; D012004:Rectal Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D016896:Treatment Outcome; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D027425:ATP-Binding Cassette, Sub-Family C Proteins; D016159:Tumor Suppressor Protein p53; C073492:ABCC4 protein, human; C495901:TP53 protein, human