Insulinlike growth factor-I-mediated migration and invasion of human colon carcinoma cells requires activation of c-Met and urokinase plasminogen activator receptor.
OBJECTIVE
To determine whether insulinlike growth factor-I (IGF-I) and hepatocyte growth factor (HGF) cooperate to induce migration and invasion of human colorectal carcinoma (CRC) cells and whether the effects of IGF-I and/or HGF are mediated through activation of the urokinase plasminogen activator (uPA)/uPA receptor (uPAR) system, a central mediator of tumor-cell migration and invasion.


BACKGROUND
CRC cells must invade through the basement membrane of the colon and migrate to form metastases. CRC cells are known to overexpress IGF-I receptor (IGF-IR), c-Met, and uPAR, 3 cell-surface receptors known to mediate cell migration and invasion. We hypothesized that IGF-IR and c-Met cooperate to induce migration and invasion in CRC cells and that this signaling is dependent on uPAR.


METHODS
KM12L4 human CRC cells were treated with IGF-I, HGF, or IGF-I + HGF in transwell migration and invasion chambers; cells that had migrated or invaded were counted. To determine the role of c-Met in IGF-I-induced migration and invasion, c-Met was inhibited by infection of cells with an adenovirus containing a c-Met ribozyme; transwell assays were then repeated. To determine the role of the uPA/uPAR system in IGF-I-induced CRC cell migration and invasion, transwell assays were repeated after pretreating cells with the uPA inhibitor amiloride or with neutralizing antibodies to uPA and uPAR.


RESULTS
IGF-I and HGF, alone or in combination, increased cell migration and invasion. The c-Met ribozyme inhibited IGF-I- and HGF-mediated migration and invasion, indicating that c-Met is essential for these processes. uPA and uPAR inhibition blocked IGF-I- and HGF-mediated migration and invasion, suggesting that uPAR is downstream of IGF/IGF-IR and HGF/c-Met in the signaling pathways that mediate cell migration and invasion.


CONCLUSIONS
IGF-I and HGF cooperate to induce migration and invasion of CRC cells, and c-Met and uPA/uPAR are required for IGF-I-mediated migration and invasion. In our in vitro model of CRC migration and invasion, uPA and uPAR appear to be downstream of IGF-IR and c-Met and are required for migration and invasion. Elucidation of the pathways that contribute to tumor progression and metastasis should provide a foundation for the rational development and use of targeted therapies for CRC.
Bauer
Todd W
TW
Department of Surgical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77230-1420, USA.
Fan
Fan
F
Liu
Wenbiao
W
Johnson
Marjorie
M
Parikh
Nila U
NU
Parry
Graham C
GC
Callahan
Jennifer
J
Mazar
Andrew P
AP
Gallick
Gary E
GE
Ellis
Lee M
LM
D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D015179:Colorectal Neoplasms / Q000473:pathology*; D017228:Hepatocyte Growth Factor / Q000502:physiology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D009361:Neoplasm Invasiveness; D019859:Proto-Oncogene Proteins c-met / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction / Q000502:physiology; D014568:Urokinase-Type Plasminogen Activator / Q000502:physiology
C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D017228:Hepatocyte Growth Factor; D007334:Insulin-Like Growth Factor I; D019859:Proto-Oncogene Proteins c-met; D014568:Urokinase-Type Plasminogen Activator