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Antibody to phosphatidylinositol 4,5-bisphosphate inhibits oncogene-induced mitogenesis
K Fukami1, K Matsuoka, O Nakanishi
1Department of Pharmacology, Tokyo Metropolitan Institute of Gerontology, Japan.
Abstract:
The hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) has been shown to be enhanced in cells transformed by some types of oncogenes and tumor viruses, but it is still unknown whether the breakdown of PIP2 plays a role in oncogene-induced cell proliferation. For examination of this problem, monoclonal antibody specifically directed to PIP2 was injected into cells. This antibody bound to endogenous PIP2 and so inhibited its intracellular breakdown. Injection of this antibody into ras-transformed cells cultured in the presence of serum caused reversible and dose-dependent decrease in proliferation and reversion of the cell morphology to that of the normal phenotype. The antibody also inhibited the proliferation of src- and erbB-transformed cells but had no effect on the proliferation of untransformed or myc-transformed cells. These results show that the breakdown of PIP2 is involved in the signaling pathways for mitogenesis in cells transformed by oncogenes such as ras, src, and erbB.
Insights
The breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2) is crucial for cell proliferation driven by oncogenes like ras, src, and erbB. Inhibiting PIP2 breakdown reverses cancer cell growth and restores normal cell appearance.
Area of Science:
- Cell Biology
- Oncology
- Biochemistry
Background:
- Phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis is elevated in oncogene- and tumor virus-transformed cells.
- The role of PIP2 breakdown in oncogene-induced cell proliferation remains unclear.
Purpose of the Study:
- To investigate the involvement of PIP2 breakdown in oncogene-induced cell proliferation.
- To determine if inhibiting PIP2 breakdown affects cancer cell growth and phenotype.
Main Methods:
- Monoclonal antibody against PIP2 was injected into cultured cells.
- Antibody binding inhibited endogenous PIP2 breakdown.
- Proliferation and morphology of ras-, src-, erbB-, and myc-transformed cells were assessed.
Main Results:
- PIP2 inhibition reduced proliferation and reverted morphology in ras-transformed cells.
- src- and erbB-transformed cells also showed inhibited proliferation.
- Untransformed and myc-transformed cells were unaffected by PIP2 inhibition.
Conclusions:
- PIP2 breakdown is a key signaling pathway for mitogenesis in ras, src, and erbB-transformed cells.
- Targeting PIP2 breakdown may offer therapeutic strategies for specific oncogene-driven cancers.