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Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors
Published on: July 17, 2020
Protein-tyrosine pseudokinase 7 (PTK7) directs cancer cell motility and metastasis
Vladislav S Golubkov1, Natalie L Prigozhina2, Yong Zhang3
1From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037, vgolubkov@sanfordburnham.org.
Abstract:
It is well established that widely expressed PTK7 is essential for vertebrate tissue morphogenesis. In cancer, the functionality of PTK7 is selectively regulated by membrane type-1 matrix metalloproteinase (MT1-MMP), ADAMs (a disintegrin domain and metalloproteinases), and γ-secretase proteolysis. Here, we established that the full-length membrane PTK7, its Chuzhoi mutant with the two functional MT1-MMP cleavage sites, and its L622D mutant with the single inactivated MT1-MMP cleavage site differentially regulate cell motility in a two-dimensional versus three-dimensional environment. We also demonstrated that in polarized cancer cells, the levels of PTK7 expression and proteolysis were directly linked to the structure and kinetics of cell protrusions, including lamellipodia and invadopodia. In the functionally relevant and widely accepted animal models of metastasis, mouse and chick embryo models, both the overexpression and knock-out of PTK7 in HT1080 cells abrogated metastatic dissemination. Our analysis of human tissue specimens confirmed intensive proteolysis of PTK7 in colorectal cancer tumors, but not in matching normal tissue. Our results provide convincing evidence that both PTK7 expression and proteolysis, rather than the level of the cellular full-length PTK7 alone, contribute to efficient directional cell motility and metastasis in cancer.
Insights
Protein tyrosine kinase 7 (PTK7) expression and proteolysis are crucial for cancer cell motility and metastasis. Both factors, not just PTK7 levels, drive directional cell movement and spread in cancer.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Widely expressed Protein tyrosine kinase 7 (PTK7) is vital for vertebrate tissue morphogenesis.
- PTK7's function in cancer is modulated by proteases like MT1-MMP, ADAMs, and γ-secretase.
Purpose of the Study:
- To investigate how full-length PTK7 and its cleavage site mutants influence cell motility in 2D and 3D environments.
- To determine the relationship between PTK7 expression, proteolysis, and cell protrusion dynamics in cancer cells.
- To evaluate the role of PTK7 in cancer metastasis using animal models and human tissue analysis.
Main Methods:
- Utilized PTK7 mutants with varying MT1-MMP cleavage site functionality.
- Assessed cell motility in 2D and 3D culture systems.
- Analyzed cell protrusion structures (lamellipodia, invadopodia) and PTK7 proteolysis.
- Employed mouse and chick embryo metastasis models with PTK7 overexpression and knock-out.
- Examined PTK7 proteolysis in human colorectal cancer tissues.
Main Results:
- PTK7 mutants differentially regulated cell motility based on the environment.
- PTK7 expression and proteolysis correlated with cell protrusion dynamics in polarized cancer cells.
- Both PTK7 overexpression and knock-out abrogated metastatic dissemination in animal models.
- Intensive PTK7 proteolysis was observed in human colorectal tumors but not normal tissue.
Conclusions:
- PTK7 expression and proteolysis are key determinants of directional cell motility and cancer metastasis.
- The interplay between PTK7 levels and its proteolytic processing is critical for metastatic potential.
- Targeting PTK7 proteolysis may offer a therapeutic strategy for inhibiting cancer spread.
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