Increased trypsin sensitivity of cell surface macromolecules after malignant transformation

Area of Science:

• Cell Biology
• Biochemistry
• Virology

Background:

• Polyoma-virus transformed cells (Py6) exhibit altered surface properties compared to normal BHK21 cells.
• Previous studies indicated differential material release from Py6 and BHK21 cells upon trypsin treatment.

Purpose of the Study:

• To investigate the effect of trypsin treatment on the electrophoretic mobility (EPM) of Py6 and BHK21 cells.
• To determine if trypsin treatment alters cell surface charge and identify the nature of the removed components.

Main Methods:

• Cells (Py6 and BHK21) were treated with 0.04% (w/v) trypsin for 3 hours.
• Electrophoretic mobility (EPM) was measured at pH 7.5 and across a range of pH values.
• Assays for cytolysis, cytotoxicity, and enzyme uptake were performed.

Main Results:

• Trypsin treatment significantly increased the negative EPM of Py6 cells, while BHK21 cells remained unchanged.
• Active trypsin enzyme was necessary for the observed EPM changes.
• No evidence of cell lysis, toxicity, or enzyme uptake was detected in treated Py6 cells.
• Analysis across different pH levels suggested removal of cationic groupings from the Py6 cell surface.

Conclusions:

• Trypsin selectively modifies the surface of polyoma-virus transformed cells (Py6), increasing their negative charge.
• The enzyme removes cationic groups from the cell surface, contributing to the altered EPM.
• These findings highlight differences in cell surface composition between transformed and normal cells.