Inhibition of protease activity in cultures of rous sarcoma virus-transformed cells: effect on the transformed...

Area of Science:

• Cell Biology
• Biochemistry
• Oncology

Background:

• The transformed phenotype in cancer cells involves complex alterations.
• Proteolytic activity is implicated in cancer cell invasiveness and metastasis.
• Rous sarcoma virus (RSV) is a retrovirus used to study cell transformation.

Purpose of the Study:

• To investigate the role of proteolytic activity in the development and maintenance of the transformed phenotype in RSV-infected cells.
• To differentiate the effects of fibrinolysis inhibition on various transformation markers.
• To identify potential proteases involved in the early stages of cell transformation.

Main Methods:

• Culturing RSV-transformed chick embryo fibroblasts in plasminogen-free medium or medium with protease inhibitors.
• Assessing morphological changes, cell adhesiveness, and hexose transport rates as markers of transformation.
• Utilizing specific trypsin inhibitors like NPGB, Soy Bean Trypsin Inhibitor, and TLCK.

Main Results:

• Inhibiting transformation-associated fibrinolysis with NPGB or Soy Bean Trypsin Inhibitor partially restored cell morphology and adhesiveness but did not affect hexose transport.
• Growing cells in plasminogen-free medium prevented morphological and adhesive changes but allowed increased hexose transport.
• TLCK effectively normalized morphology, adhesiveness, and hexose transport, despite not inhibiting fibrinolysis, suggesting involvement of other proteases.

Conclusions:

• Fibrinolytic activity is crucial for the morphological and adhesive alterations associated with the transformed phenotype.
• Increased hexose transport in transformed cells is independent of fibrinolytic activity.
• A protease other than those involved in fibrinolysis may play an earlier role in the genesis of the transformed phenotype.