title: [Mechanism of lysyl oxidase (LOX) in breast cancer invasion and metastasis].
abstract: OBJECTIVE
  To investigate possible mechanism of silencing lysyl oxidase (LOX) gene by RNA interference affecting on invasion and metastasis of breast cancer cells.
  
  
  METHODS
  LOX-RNAi-LV was designed and synthesized, which was transfected into breast cancer cell line MDA-MB-231. The expressions of LOX, MMP-2 and MMP-9 were determined by Real-time PCR in MDA-MB-231 cells, and the protein expression of LOX was determined by Western blot. The cells migration and invasion abilities were measured by cell migration and invasion test. 111 cases of breast cancer tissue and cancer-adjacent breast tissues and 20 cases of benign lesion tissues of LOX, MMP-2 and MMP-9 were detected by immunohistochemistry, and the relationship of LOX and clinicopathological characteristics was analyzed.
  
  
  RESULTS
  The expression levels of LOX mRNA and protein were down-regulated obviously after transfecting LOX-RNAi-LV, with the inhibition rate 89.2% ± 1.3% and 84.4% ± 0.4% respectively. The relative expressions of MMP-2 and MMP-9 mRNA were 0.496 ± 0.021 and 0.571 ± 0.099 in RNAi group, which was significantly lower than that in negative control group (0.846 ± 0.047, 0.786 ± 0.042) and blank control group (1.000 ± 0.000, 1.000 ± 0.000) (both P < 0.05). Cell migration and invasion test showed the average cell numbers per field in the group RNAi were 47 ± 2 and 63 ± 2, was significantly lower than that in negative control group (100 ± 1, 118 ± 2) and blank control group (100 ± 1, 118 ± 2) (both P < 0.05). The expression of LOX protein in breast cancer, cancer-adjacent breast tissues and benign breast tumor were 48.6% (54/111), 26.1% (29/111), 20.0% (4/20), the expression of LOX protein in breast cancer was significantly higher than that in cancer-adjacent breast tissues and benign lesion tissues (P = 0.019). The expression of LOX protein was associated with clinical stage, lymph node metastasis, tumor size. Correlation analysis showed that LOX protein expression was significantly positive correlation with MMP-2 (r = 0.262, P = 0.005) and MMP-9 (r = 0.424, P = 0.000).
  
  
  CONCLUSIONS
  LOX can promote invasion and metastasis of breast cancer; LOX and MMP-2, MMP-9 may have a synergistic role in promoting invasion and metastasis of breast cancer.
authors.affiliation: Department of Breast Surgery, Cancer Hospital, Guangxi Medical University, Nanning 530021, China. jianlunliu@hotmail.com
authors.forename: Jian-lun
authors.initials: JL
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.forename: Yi
authors.initials: Y
authors.lastname: Jiang
authors.forename: Hua-wei
authors.initials: HW
authors.lastname: Yang
authors.forename: Jing-tao
authors.initials: JT
authors.lastname: Li
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D008249:Protein-Lysine 6-Oxidase / Q000378:metabolism*; D014162:Transfection
chemical_list: D008249:Protein-Lysine 6-Oxidase; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9