Hepatocyte growth factor activation inhibitors (HAI-1 and HAI-2) regulate HGF-induced invasion of human breast cancer cells

Int J Cancer. 2006 Sep 1;119(5):1176-83. doi: 10.1002/ijc.21881.


Hepatocyte growth factor (HGF) plays a plethora of roles in cancer metastasis and tumour growth. The interaction between tumour cells and their surrounding stromal environment is a crucial factor regulating tumour invasion and metastasis. Stromal fibroblasts are the main source of HGF in the body, and release HGF as an inactive precursor (pro-HGF). HGF activator (HGFA), matriptase, urokinase-type plasminogen activator and hepsin are the main factors responsible for converting pro-HGF into active HGF. HAI-1 and HAI-2 are 2 novel Kunitz-type serine protease inhibitors that regulate HGF activity through inhibition of HGFA, matriptase and hepsin action. Recent studies demonstrate that HAI-1 and HAI-2 may also potently inhibit a number of other pro-metastatic serine proteases and therefore have direct bearing on the spread of tumours. Our study examined the potential of these HAI's to suppress the influence of HGF and regulate cancer metastasis. We generated a retroviral expression system that induced HAI expression in a human fibroblast cell line. Forced expression of either HAI-1 or HAI-2 in these fibroblasts resulted in a dramatic decrease in the production of bioactive hepatocyte growth factor (HGF). This reduction in HGF activity subsequently suppressed HGF's metastatic influence on breast cancer cells. To further assess the anti-cancer properties of HAI-1 and HAI-2 we generated recombinant HAI proteins. These recombinant HAI proteins possessed the ability to potently quench HGF activity. We also demonstrate that these recombinant HAI's suppressed fibroblast-mediated breast cancer invasion. An additional ribozyme transgenes study revealed that elimination of HAI-1 and HAI-2 expression, in an MDA-MB-231 breast cancer cell line, significantly enhanced the migratory, proliferative and invasive nature of these breast cancer cells. Overall, our data demonstrates the important roles of HAI-1 and HAI-2 in cancer metastasis, and reveals that these serine protease inhibitors display strong therapeutic potential.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Base Sequence
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Line
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology
  • Dogs
  • Female
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Humans
  • Kidney / cytology
  • Kidney / metabolism
  • Male
  • Membrane Glycoproteins / metabolism*
  • Membrane Glycoproteins / pharmacology*
  • Molecular Sequence Data
  • Neoplasm Invasiveness
  • Neoplasms / drug therapy
  • Neoplasms / metabolism*
  • Neoplasms / pathology*
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology
  • Proteinase Inhibitory Proteins, Secretory
  • RNA, Catalytic / genetics
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Retroviridae
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serine Endopeptidases / metabolism
  • Serine Proteinase Inhibitors / metabolism*
  • Serine Proteinase Inhibitors / pharmacology
  • Transgenes
  • Trypsin Inhibitor, Kunitz Soybean / metabolism*
  • Trypsin Inhibitor, Kunitz Soybean / pharmacology*
  • Urokinase-Type Plasminogen Activator / metabolism


  • Antineoplastic Agents
  • Membrane Glycoproteins
  • Proteinase Inhibitory Proteins, Secretory
  • RNA, Catalytic
  • Recombinant Proteins
  • SPINT1 protein, human
  • SPINT2 protein, human
  • Serine Proteinase Inhibitors
  • Trypsin Inhibitor, Kunitz Soybean
  • Serine Endopeptidases
  • hepsin
  • matriptase
  • ST14 protein, human
  • Urokinase-Type Plasminogen Activator