measuring-cell-edge-protrusion-dynamics-during-spreading-using-live

Measuring Cell-Edge Protrusion Dynamics during Spreading using Live-Cell Microscopy

The development and homeostasis of multicellular organisms rely on coordinated regulation of cell migration. Cell migration is an essential event in the ...

The nonreceptor tyrosine kinase Pyk2 is highly expressed in invasive breast cancer, but the mechanism by which it potentiates tumor cell invasiveness is unclear at present. Using high-throughput protein array screening and bioinformatic analysis, we identified cortactin as a novel substrate and interactor of proline-rich tyrosine kinase 2 (Pyk2). Pyk2 colocalizes with cortactin to invadopodia of invasive breast cancer cells, where it mediates epidermal growth factor-induced cortactin tyrosine phosphorylation both directly and indirectly via Src-mediated Abl-related gene (Arg) activation, leading to actin polymerization in invadopodia, extracellular matrix degradation, and tumor cell invasion. Both Pyk2 and the closely related focal adhesion kinase (FAK) regulate tumor cell invasion, albeit via distinct mechanisms. Although Pyk2 regulates tumor cell invasion by controlling invadopodium-mediated functions, FAK controls invasiveness of tumor cells by regulating focal adhesion-mediated motility. Collectively, our findings identify Pyk2 as a unique mediator of invadopodium formation and function and also provide a novel insight into the mechanisms by which Pyk2 mediates tumor cell invasion.

Pyk2 and FAK differentially regulate invadopodia formation and function in breast cancer cells.

Metastatic dissemination of cancer cells from the primary tumor and their spread to distant sites in the body is the leading cause of mortality in breast cancer patients. While researchers have identified treatments that shrink or slow metastatic tumors, no treatment that permanently eradicates metastasis exists at present. Here, we show that the ABL kinase inhibitors imatinib, nilotinib, and GNF-5 impede invadopodium precursor formation and cortactin-phosphorylation dependent invadopodium maturation, leading to decreased actin polymerization in invadopodia, reduced extracellular matrix degradation, and impaired matrix proteolysis-dependent invasion. Using a mouse xenograft model we demonstrate that, while primary tumor size is not affected by ABL kinase inhibitors, the  matrix metalloproteinase (MMP) activity, tumor cell invasion, and consequent spontaneous metastasis to lungs are significantly impaired in inhibitor-treated mice. Further proteogenomic analysis of breast cancer patient databases revealed co-expression of the Abl-related gene (Arg) and cortactin across all hormone- and human epidermal growth factor receptor 2 (HER2)-receptor status tumors, which correlates synergistically with distant metastasis and poor patient prognosis. Our findings establish a prognostic value for Arg and cortactin as predictors of metastatic dissemination and suggest that therapeutic inhibition of ABL kinases may be used for blocking breast cancer metastasis.

Targeting invadopodia-mediated breast cancer metastasis by using ABL kinase inhibitors.

Focal adhesion kinase (FAK) is well established as a regulator of cell migration, but whether and how the closely related proline-rich tyrosine kinase 2 (Pyk2) regulates fibroblast motility is still under debate. Using mouse embryonic fibroblasts (MEFs) from Pyk2 mice, we show here, for the first time, that lack of Pyk2 significantly impairs both random and directed fibroblast motility. Pyk2 MEFs show reduced cell-edge protrusion dynamics, which is dependent on both the kinase and protein-protein binding activities of Pyk2. Using bioinformatics analysis of in vitro high- throughput screens followed by text mining, we identified CrkI/II as novel substrates and interactors of Pyk2. Knockdown of CrkI/II shows altered dynamics of cell-edge protrusions, which is similar to the phenotype observed in Pyk2 MEFs. Moreover, epistasis experiments suggest that Pyk2 regulates the dynamics of cell-edge protrusions via direct and indirect interactions with Crk that enable both activation and down-regulation of Crk-mediated cytoskeletal signaling. This complex mechanism may enable fine-tuning of cell-edge protrusion dynamics and consequent cell migration on the one hand together with tight regulation of cell motility, a process that should be strictly limited to specific time and context in normal cells, on the other hand.

Article	Year
Pyk2 and FAK differentially regulate invadopodia formation and function in breast cancer cells. The Journal of cell biology\| PubMed ID: 29133485	2018
Targeting invadopodia-mediated breast cancer metastasis by using ABL kinase inhibitors. Oncotarget\| PubMed ID: 29774130	2018
Pyk2 regulates cell-edge protrusion dynamics by interacting with Crk. Molecular biology of the cell\| PubMed ID: 34432482	2021

Nikola Lukic

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