Epidermal growth factor downregulates the expression of SH-PTP2.
Protein phosphorylation/dephosphorylation on tyrosine residues are regulated by tyrosine kinases/phosphatases. The tyrosine phosphatase SH-PTP2 (PTP1D, PTP2C) interacts physically through its SH2 domain with phosphorylated epidermal growth factor receptor (EGFR). In KB cells, an oral epidermoid carcinoma, high epidermal growth factor (EGF) concentrations (10-9, 10-8 and 10-7 M) downregulate its receptor for the duration of the incubation with EGF. Thus, it was hypothesized that in KB cells, SH-PTP2 expression would also be downregulated by high EGF concentrations. This hypothesis was investigated by incubating the KB cells with increasing concentrations of EGF (0, 10-11, 10-10, 10-9, 10-8, 10-7 M) and by evaluating the expression of SH-PTP2 protein under these conditions. This study showed that EGF 10-7 and 10-8 M significantly decreased SH-PTP2 protein expression compared to controls. EGF 10-10 and 10-11 M did not change the expression of SH-PTP2 protein. We conclude that high EGF concentrations downregulate the expression of SH-PTP2 protein.
Kamer
A R
AR
Oral Maxillofacial Department, School of Dental Medicine, SUNY at Buffalo, NY 14214, USA.
Hoghooghi
S A
SA
Liebow
C
C
D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000187:drug effects / Q000378:metabolism*; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D013997:Time Factors; D014407:Tumor Cells, Cultured; D018909:src Homology Domains / Q000187:drug effects / Q000502:physiology*
D047908:Intracellular Signaling Peptides and Proteins; D004815:Epidermal Growth Factor; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases