Specific requirement for the p85-p110alpha phosphatidylinositol 3-kinase during epidermal growth factor-stimulated actin nucleation in breast cancer cells.
We have studied the role of phosphatidylinositol 3-kinases (PI 3-kinases) in the regulation of the actin cytoskeleton in MTLn3 rat adenocarcinoma cells. Stimulation of MTLn3 cells with epidermal growth factor (EGF) induced a rapid increase in actin polymerization, with production of lamellipodia within 3 min. EGF-stimulated lamellipodia were blocked by 100 nM wortmannin, suggesting the involvement of a class Ia PI 3-kinase. MTLn3 cells contain equal amounts of p110alpha and p110beta, and do not contain p110delta. Injection of specific inhibitory antibodies to p110alpha induced cell rounding and blocked EGF-stimulated lamellipod extension, whereas control or anti-p110beta antibodies had no effect. In contrast, both antibodies inhibited EGF-stimulated DNA synthesis. An in situ assay for actin nucleation showed that EGF-stimulated formation of new barbed ends was blocked by injection of anti-p110alpha antibodies. In summary, the p110alpha isoform of PI 3-kinase is specifically required for EGF-stimulated actin nucleation during lamellipod extension in breast cancer cells.
Hill
K
K
Departments of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Welti
S
S
Yu
J
J
Murray
J T
JT
Yip
S C
SC
Condeelis
J S
JS
Segall
J E
JE
Backer
J M
JM
D000199:Actins / Q000378:metabolism*; D000230:Adenocarcinoma; D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001943:Breast Neoplasms; D003599:Cytoskeleton / Q000378:metabolism; D004261:DNA Replication; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007527:Isoenzymes / Q000276:immunology; D008845:Microinjections; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
D000199:Actins; D000730:Androstadienes; D000906:Antibodies; D007527:Isoenzymes; D004815:Epidermal Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D000077191:Wortmannin