Cripto-1 overexpression leads to enhanced invasiveness and resistance to anoikis in human MCF-7 breast cancer cells.
Cripto-1 (CR-1) is an epidermal growth factor (EGF)-CFC protein that has been shown to signal through nodal/Alk-4, PI3K/Akt, and/or ras/raf/MEK/MAPK pathways in mammalian cells, and that is frequently expressed in human primary breast carcinomas. In the present study, the human estrogen receptor positive, MCF-7 breast cancer cell line, that expresses low levels of endogenous CR-1, was transfected with a CR-1 expression vector. MCF-7 CR-1 cells expressed high levels of a 25 kDa recombinant CR-1 protein that was not detected in MCF-7 cells transfected with a control vector (MCF-7 neo). Overexpression of CR-1 did not induce an estrogen independent phenotype in MCF-7 cells. In fact, MCF-7 CR-1 cells showed a response to exogenous estrogens that was similar to MCF-7 neo cells, and failed to grow in immunosuppressed mice in absence of estrogen stimulation. However, MCF-7 CR-1 cells showed a rate of proliferation in serum free conditions, and an ability to form colonies in soft-agar that were higher as compared with MCF-7 neo cells. More importantly, overexpression of CR-1 enhanced the resistance to anoikis and the invasion ability of MCF-7 cells. MCF-7 CR-1 cells showed levels of activation of both Akt and Smad-2 that were significantly higher as compared with MCF-7 neo. These findings suggest that CR-1 overexpression might be associated with the progression towards a more aggressive phenotype in breast carcinoma, through the activation of both Akt and Smad-2 signalling pathways.
Normanno
Nicola
N
Division of Haematological Oncology and Department of Experimental Oncology, INT-Fondazione Pascale, Naples, Italy. nicnorm@yahoo.com
De Luca
Antonella
A
Bianco
Caterina
C
Maiello
Monica R
MR
Carriero
Maria V
MV
Rehman
Aasia
A
Wechselberger
Christian
C
Arra
Claudio
C
Strizzi
Luigi
L
Sanicola
Michele
M
Salomon
David S
DS
D000818:Animals; D023102:Anoikis / Q000502:physiology*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins / Q000378:metabolism; D004815:Epidermal Growth Factor; D005260:Female; D058851:GPI-Linked Proteins; D006133:Growth Substances / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D051379:Mice; D008819:Mice, Nude; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009368:Neoplasm Transplantation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D051899:Smad2 Protein; D015534:Trans-Activators / Q000378:metabolism
D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D058851:GPI-Linked Proteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; C497782:SMAD2 protein, human; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; C070636:TDGF1 protein, human; C489450:Tdgf1 protein, mouse; D015534:Trans-Activators; D004815:Epidermal Growth Factor; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases