Silencing of lysyl oxidase gene expression by RNA interference suppresses metastasis of breast cancer

Asian Pac J Cancer Prev. 2012;13(7):3507-11. doi: 10.7314/apjcp.2012.13.7.3507.

Abstract

Objective: The aim of this study was to investigate possible mechanisms of LOX gene effects on invasion and metastasis of breast cancer cells by RNA interference.

Methods: LOX-RNAi-LV was designed, synthesized, and then transfected into a breast cancer cell line (MDA-MB-231). Expression of LOX, MMP-2 and MMP-9 was determined by real-time PCR, and protein expression of LOX by Western blotting. Cell migration and invasiveness were assessed with Transwell chambers. A total of 111 cases of breast cancer tissues, cancer-adjacent normal breast tissues, and 20 cases of benign lesion tissues were assessed by immunohistochemistry.

Results: Expression of LOX mRNA and protein was suppressed, and the expression of MMP-2 and MMP-9 was significantly lower in the RNAi group than the control group (P<0.05), after LOX-RNAi-LV was transfection into MDA-MB-231 cells. Migration and invasion abilities were obviously inhibited. The expression of LOX protein in breast cancer, cancer-adjacent normal breast tissues and benign breast tumor were 48.6% (54/111), 26.1% (29/111), 20.0% (4/20), respectively, associations being noted with clinical stage, lymph node metastasis, tumor size and ER, PR, HER2, but not age. LOX protein was positively correlated with MMP-2 and MMP-9.

Conclusion: LOX displayed an important role in invasion and metastasis of breast cancer by regulating MMP-2 and MMP-9 expression which probably exerted synergistic effects on the extracellular matrix (ECM).

MeSH terms

  • Breast Neoplasms / enzymology*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Female
  • Gene Silencing
  • Humans
  • Lymphatic Metastasis
  • Matrix Metalloproteinase 2 / genetics
  • Matrix Metalloproteinase 9 / genetics
  • Middle Aged
  • Neoplasm Invasiveness
  • Protein-Lysine 6-Oxidase / biosynthesis*
  • Protein-Lysine 6-Oxidase / deficiency
  • Protein-Lysine 6-Oxidase / genetics*
  • RNA Interference
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Transfection / methods

Substances

  • RNA, Messenger
  • Protein-Lysine 6-Oxidase
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9