Activity-based protein profiling implicates urokinase activation as a key step in human fibrosarcoma intravasation

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Malignant cell intravasation requires extracellular matrix remodeling.
• The circulatory system facilitates tumor cell transport and metastasis.
• Understanding the enzymes involved in intravasation is crucial for cancer research.

Purpose of the Study:

• To identify serine hydrolases contributing to tumor cell intravasation.
• To compare enzyme activity in high and low intravasating fibrosarcoma cell lines.
• To elucidate the specific role of urokinase-type plasminogen activator (uPA) in metastasis.

Main Methods:

• Activity-based protein profiling of HT-1080 fibrosarcoma variants.
• In vitro Matrigel invasion assays.
• In vivo chick embryo chorioallantoic membrane model for intravasation and metastasis.
• Quantitative human-specific Alu PCR for measuring intravasation.
• Pharmacological inhibition of uPA activity.

Main Results:

• Activity-based protein profiling identified altered serine hydrolase activity between high and low intravasating cells.
• Urokinase-type plasminogen activator (uPA) showed the most significant activity difference.
• Active uPA, not its zymogen, was found in conditioned medium of highly invasive cells.
• uPA inhibition reduced in vitro invasion and in vivo intravasation/metastasis.
• Exogenous active uPA enhanced intravasation in low invasive tumors.

Conclusions:

• Active urokinase-type plasminogen activator (uPA) significantly promotes tumor cell intravasation.
• uPA activation is a critical step in cancer cell metastasis.
• Targeting uPA activity may offer a therapeutic strategy against cancer spread.