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Transformation and Stat activation by derivatives of FGFR1, FGFR3, and FGFR4
K C Hart1, S C Robertson, M Y Kanemitsu
1Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla 92093-0367, USA.
Abstract:
The fibroblast growth factor receptor (FGFR) family members mediate a number of important cellular processes, and are mutated or overexpressed in several forms of human cancer. Mutation of Lys650-->Glu in the activation loop of the FGFR3 kinase domain causes the lethal human skeletal disorder thanatophoric dysplasia type II (TDII) and is also found in patients with multiple myeloma, bladder and cervical carcinomas. This mutation leads to constitutive activation of FGFR3. To compare the signaling activity of FGFR family members, this activating mutation was generated in FGFR1, FGFR3, and FGFR4. We show that the kinase domains of FGFR1, FGFR3, and FGFR4 containing the activation loop mutation, when targeted to the plasma membrane by a myristylation signal, can transform NIH3T3 cells and induce neurite outgrowth in PC12 cells. Phosphorylation of Shp2, PLC-gamma, and MAPK was also stimulated by all three 'TDII-like' FGFR derivatives. Additionally, activation of Stat1 and Stat3 was observed in cells expressing the activated FGFR derivatives. Finally, we demonstrate that FGFR1, FGFR3, and FGFR4 derivatives can stimulate PI-3 kinase activity. Our comparison of these activated receptor derivatives reveals a significant overlap in the panel of effector proteins used to mediate downstream signals. This also represents the first demonstration that activation of FGFR4, in addition to FGFR1 and FGFR3, can induce cellular transformation. Moreover, our results suggest that Stat activation by FGFRs is important in their ability to act as oncogenes.
Insights
Activating mutations in fibroblast growth factor receptors (FGFRs) like FGFR3 can cause developmental disorders and cancer. This study shows activated FGFR1, FGFR3, and FGFR4 can transform cells and activate similar signaling pathways, highlighting their oncogenic potential.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- Fibroblast growth factor receptors (FGFRs) are crucial for cellular processes.
- Mutations and overexpression of FGFRs are implicated in various human cancers.
- A specific FGFR3 mutation (Lys650-->Glu) causes thanatophoric dysplasia type II and is found in multiple myeloma and carcinomas, leading to constitutive activation.
Purpose of the Study:
- To compare the signaling activities of FGFR1, FGFR3, and FGFR4.
- To investigate the effects of an activating mutation (Lys650-->Glu) in different FGFR family members.
- To determine the downstream signaling pathways activated by these mutated FGFRs and their role in cellular transformation and oncogenesis.
Main Methods:
- Generated an activating mutation (Lys650-->Glu) in the kinase domain of FGFR1, FGFR3, and FGFR4.
- Targeted these mutated FGFRs to the plasma membrane using a myristylation signal.
- Assessed cellular transformation of NIH3T3 cells and neurite outgrowth in PC12 cells.
- Measured the phosphorylation of downstream signaling proteins including Shp2, PLC-gamma, MAPK, Stat1, Stat3, and PI-3 kinase activity.
Main Results:
- Activated FGFR1, FGFR3, and FGFR4 derivatives induced NIH3T3 cell transformation and PC12 cell neurite outgrowth.
- All three activated FGFR derivatives stimulated phosphorylation of Shp2, PLC-gamma, and MAPK.
- Activation of Stat1, Stat3, and PI-3 kinase was observed in cells expressing the activated FGFR derivatives.
- Demonstrated that activated FGFR4 can induce cellular transformation, similar to FGFR1 and FGFR3.
Conclusions:
- Activated FGFR1, FGFR3, and FGFR4 share overlapping downstream effector proteins.
- Activation of FGFR4, alongside FGFR1 and FGFR3, can lead to cellular transformation.
- Stat activation by FGFRs appears critical for their oncogenic function.