Cooperative effect of hepatocyte growth factor and fibronectin in anchorage-independent survival of mammary carcinoma cells: requirement for phosphatidylinositol 3-kinase activity.
Anchorage-independent survival and growth are critical characteristics of malignant cells. We showed previously that the addition of exogenous hepatocyte growth factor (HGF) and the presence of fibronectin fibrils stimulate anchorage-independent colony growth of a murine mammary carcinoma, SP1, which expresses both HGF and HGF receptor (Met; R. Saulnier et al., Exp. Cell Res., 222: 360-369, 1996). We now show that tyrosine phosphorylation of Met in carcinoma cells is augmented by cell adhesion and spreading on fibronectin substratum. In contrast, detached serum-starved cells exhibit reduced tyrosine phosphorylation of Met and undergo apoptotic cell death within 18-24 h. Under these conditions, the addition of HGF stimulates tyrosine phosphorylation of Met and restores survival of carcinoma cells. Soluble fibronectin also stimulates cell survival and shows a cooperative survival response with HGF but does not affect tyrosine phosphorylation of Met; these results indicate that fibronectin acts via a pathway independent of Met in detached cells. We demonstrated previously that inhibition of phosphatidylinositol (PI) 3-kinase activity blocks HGF-induced DNA synthesis of carcinoma cells (N. Rahimi et al., J. Biol. Chem., 271: 24850-24855, 1996). We now show in detached cells a cooperative effect of HGF and FN in the activation of PI 3-kinase and on the phosphorylation of PKB/Akt at serine 473. PI 3-kinase activity is also required for the HGF- and fibronectin-induced survival responses, as well as anchorage-independent colony growth. However, c-Src kinase or MEK1/2 activities are not required for the cell survival effect. Together, these results demonstrate that the PI 3-kinase/Akt pathway is a key effector of the HGF- and fibronectin-induced survival response of breast carcinoma cells under detached conditions and corroborate an interaction between integrin and HGF/ Met signalling pathways in the development of invasive breast cancer.
Qiao
H
H
Department of Pathology, Queen's University, Kingston, Ontario, Canada.
Saulnier
R
R
Patryzkat
A
A
Rahimi
N
N
Raptis
L
L
Rossiter
J
J
Tremblay
E
E
Elliott
B
B
D000818:Animals; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000201:enzymology / Q000473:pathology*; D002448:Cell Adhesion; D002470:Cell Survival; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D005260:Female; D005353:Fibronectins / Q000494:pharmacology*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology / Q000473:pathology*; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D002867:Chromones; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D005353:Fibronectins; D017228:Hepatocyte Growth Factor; D009025:Morpholines; D009363:Neoplasm Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019859:Proto-Oncogene Proteins c-met; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one