Open AccessActivation of focal adhesion kinase in human lung cancer cells involves multiple and potentially parallel signaling events
Author(s) -
Mukhopadhyay Nishit K.,
Gordon Gavin J.,
Chen ChangJie,
Bueno Raphael,
Sugarbaker David J.,
Jaklitsch Michael T.
Publication year - 2005
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/j.1582-4934.2005.tb00364.x
Subject(s) - focal adhesion , paxillin , calphostin c , phosphorylation , integrin , microbiology and biotechnology , ptk2 , autophosphorylation , signal transduction , cell adhesion , kinase , chemistry , cytochalasin d , biology , cancer research , protein kinase c , cytoskeleton , protein kinase a , cell , biochemistry , mitogen activated protein kinase kinase
Integrins are adhesion receptors that transmit signals bidirectionally across the plasma membrane. In our previous report we have shown that the squamous lung cancer cell line, Calu‐1, binds to collagen type IV (Coll IV) through β 1 ‐integrin and results in phosphorylation of focal adhesion kinase (FAK) (Ann Thorac Surg 2004; 78:450‐7). Considering the critical role of FAK in cell migration, proliferation, and survival, here we investigated potential mechanisms of its activation and regulation in Calu‐1 cells. We observed the phosphorylation of Tyr 397 of FAK (the autophosphorylation site of FAK) and paxillin, the immediate downstream substrate of FAK following the adhesion of Calu‐1 cells to Coll IV. FAK remains phosphorylated during proliferation either on Coll IV or on uncoated plates for 72 h, as determined by peroxivanadate treatment. Exposure of Calu‐1 cells with 60 μM genistein, reduces FAK phosphorylation (7.6 fold) and cell proliferation. Extracellular signal regulated kinases (ERKs) were also phosphorylated after Coll IV attachment. Disruption of Calu‐1 cell cytoskeleton integrity by 1–5 μM Cytochalasin D resulted in the inhibition of cell adhesion (50% to 75%, p<0.19–6.6×10 ‐7 ) and ERKs phosphorylation (2 fold) without any effect on FAK phosphorylation. Protein Kinase C inhibitor, Calphostin C at 100 and 250 nM concentrations did not block Coll IV induced FAK phosphorylation, but activated the ERKs in a dose dependent manner. β 1 ‐integrin is essential for Coll IV induced FAK activation, but it is not physically associated with FAK as determined by immunodetection assay. Collectively, this report defines the existence of multiple and potentially parallel Coll IV/β 1 ‐integrin mediated signaling events in Calu‐1 cells, which involve FAK, ERKs, and PKC.